Jet turbine reliability

[Jim Pengelly]

I'm considering ordering a JS1-C TJ with the jet turbine. A potential syndicate partner is concerned about the reliability of jet turbines from a 'will it start' point of view and a repair cost point of view. I imagine electric turbos are going to be more reliable because of the relative simplicity but you can't buy an electric JS1 or 29. Any comments on jet reliability?

[Kevin Neave[_2_]]

The JS1, especially the one you flew, is good enough that you'll probably
never find out if the jet is reliable or not.

KN

At 10:31 01 June 2015, Jim Pengelly wrote:
>I'm considering ordering a JS1-C TJ with the jet turbine. A potential
>synd=
>icate partner is concerned about the reliability of jet turbines from a
>'wi=
>ll it start' point of view and a repair cost point of view. I imagine
>elec=
>tric turbos are going to be more reliable because of the relative
>simplicit=
>y but you can't buy an electric JS1 or 29. Any comments on jet
>reliability=
>?
>

[Jim Pengelly]

On Monday, June 1, 2015 at 6:00:06 PM UTC+2, Kevin Neave wrote:
> The JS1, especially the one you flew, is good enough that you'll probably
> never find out if the jet is reliable or not.
>
> KN
>
> At 10:31 01 June 2015, Jim Pengelly wrote:
> >I'm considering ordering a JS1-C TJ with the jet turbine. A potential
> >synd=
> >icate partner is concerned about the reliability of jet turbines from a
> >'wi=
> >ll it start' point of view and a repair cost point of view. I imagine
> >elec=
> >tric turbos are going to be more reliable because of the relative
> >simplicit=
> >y but you can't buy an electric JS1 or 29. Any comments on jet
> >reliability=
> >?
> >
Yeah - I would have had to try pretty hard to land out in that glider - it goes incredibly well.

[[email protected]]

I witnessed a jet-powered glider at the EAA event in Oshkosh.

My immediate thought was we could not allow them to fly at our gliderport.

The noise was beyond imagination. The neighbors simply would not tolerate the noise.

Tom Knauff

[Jim Pengelly]

On Monday, June 1, 2015 at 7:58:58 PM UTC+2, wrote:
> I witnessed a jet-powered glider at the EAA event in Oshkosh.
>
> My immediate thought was we could not allow them to fly at our gliderport.
>
> The noise was beyond imagination. The neighbors simply would not tolerate the noise.
>
> Tom Knauff
You make a fair point. JS1 is not a self launcher so in all probability the jet will only be used out over deserted farm land far from the home airfield.

[[email protected]]

On Monday, June 1, 2015 at 1:58:58 PM UTC-4, wrote:
> I witnessed a jet-powered glider at the EAA event in Oshkosh.
>
> My immediate thought was we could not allow them to fly at our gliderport..
>
> The noise was beyond imagination. The neighbors simply would not tolerate the noise.
>
> Tom Knauff

Mr. Knauff, I'm guessing you are referring to Bob "Airshow Bob" Carlton's Super Salto or BonusJet or SubSonex aircrafts which are all self launching and/or "show center" aircraft. You are correct that they are loud.

However, comparing one of Bob's aircraft to a JS-1 jet sustainer is an apples to oranges comparison. A sustainer jet has a totally different footprint and is not purposed to continually operate in the "cylinder" of a gliderport. Given a choice, your rural Ridge Soaring neighbors (or any other airport neighbors) would probably prefer the occasional passing "swoosh' of a sustainer jet as opposed to the frequent roar of your daily tow plane operation.

[[email protected]]

I'll believe it when I hear it.
Tom

[JS]

Was given a JS1 engine start demo at Lake Keepit, it's pretty simple. Correction, very simple.
We were right next to it, in an open hangar and it wasn't deafening.
Also witnessed a powered JS1 low pass, quiet compared to a straight-pipe exhaust airplane. It is loud compared to a normal unpowered glider low pass.
While putting the glider away today, there were two (52 Lb thrust) turbine runs after overhaul at JetCat. Believe an air compressor is as loud at an equal distance, much louder if there's a die grinder involved.
Flown with Bob Carlton in the Bonus Jet. With the same (247 Lb thrust) TJ100 as used on the Salto it is quite a bit noisier than a JS1J (92 Lb thrust) but still not hideous when you consider it's a self-launcher that can out-climb most towplanes. Perhaps it's just odd to look at a glider and hear that sound.
Jim


On Monday, June 1, 2015 at 12:37:12 PM UTC-7, wrote:
> I'll believe it when I hear it.
> Tom

[krasw]

Surely jet engine cannot be more unreliable than Solo two-stroke that you need to dive to start. If it would, you would be lucky to start it even once.

[[email protected]]

On Tuesday, June 2, 2015 at 7:34:47 AM UTC-7, krasw wrote:
> Surely jet engine cannot be more unreliable than Solo two-stroke that you need to dive to start. If it would, you would be lucky to start it even once.

Solos don't need a dive to start. You can start them that way if your starter battery is dead but normally you never need to do this.

Anyways, Jim, I think once you get used to starting a turbine you'll find its very reliable. But, it can fail to start.. things like a failed thermocouple is all it takes for the start sequence to halt. Also too much air in the line can do it if the lines weren't purged properly... clogged line filters can create a low rpm fail start. Otherwise, properly maintainted they work great with a well charged starter/ignition battery.

[krasw]

On Tuesday, 2 June 2015 21:40:56 UTC+3, wrote:
> On Tuesday, June 2, 2015 at 7:34:47 AM UTC-7, krasw wrote:
> > Surely jet engine cannot be more unreliable than Solo two-stroke that you need to dive to start. If it would, you would be lucky to start it even once.
>
> Solos don't need a dive to start. You can start them that way if your starter battery is dead but normally you never need to do this.
>

I was obviously talking about turbos, which you have to dive to start. There is only handful of turbos with electric starter (for some unimaginable reason).

There on single moving (rotating) part in a turbine. Compare that to shaking two-stroke held together with a bucket of tiewraps.

[Dan Marotta]

That's what I thought.

On 6/2/2015 7:47 PM, wrote:
> They are MODEL engines and are not "man rated" by the FAA. There are several YT vids showing how they are built and assembled. Watch these and then determine if you ever want to put your "skin on the line" using one. By comparison, the Williams FJ-44 is a small TURBOFAN originally built to power US cruise missiles. It had to demonstrate extreme reliability before it was FAA certified and man rated for use on very light business jets. Not to mention it was originally designed to stringent military specs. Bottom line again, these are model TURBOJET engines. Never put your safety/life in a position where their reliability matters.

--
Dan Marotta

[Dan Marotta]

OK, then.

On 6/2/2015 11:31 PM, wrote:
> ... and I'd be surprised if some of the new crop of small European turbines weren't being made with an eye on the expanding UAV market - I can't see how the time and money being spent on them can be recouped in the glider market alone.

--
Dan Marotta

[Steve Parker[_2_]]

Let's hope that that single rotating part has been made and assembled with
the proper controls.
Something rotating at 100,000 rpm about 3 feet from your head had better be
good.
Contained failure would mean bullets being fired at your fin/tailplane.
Uncontained failure and you had better have a good parachute, assuming you
survive the explosion!!

>There on single moving (rotating) part in a turbine. Compare that to
>shaking two-stroke held together with a bucket of tiewraps.
>

[Brett]

That's what I thought.

On 6/2/2015 7:47 PM, wrote:
They are MODEL engines and are not "man rated" by the FAA. There are several YT vids showing how they are built and assembled. Watch these and then determine if you ever want to put your "skin on the line" using one. By comparison, the Williams FJ-44 is a small TURBOFAN originally built to power US cruise missiles. It had to demonstrate extreme reliability before it was FAA certified and man rated for use on very light business jets. Not to mention it was originally designed to stringent military specs. Bottom line again, these are model TURBOJET engines. Never put your safety/life in a position where their reliability matters.

--
Dan Marotta

No Dan, the TJ42 turbine used in the JS1 Revelation has been developed from scratch specifically for the sailplane market. They have never been used in anything but sailplanes and comprehensive testing has been completed for certification. I have had the privilege of visiting the factory in Northern Germany and was very impressed with the dedicated plant and the professionalism of the staff.

Brett

[[email protected]]

Hazard is to the rear engine and its mounted behind you. I remember seeing that some of these also had a containment housing. So, I think they have addressed the issue. But it makes one heck of a pop if they do shed a blade! This will be about the only time a turbine will vibrate as it winds down..

[Alexander Georgas[_2_]]

Having flown a land-mower piston engine for quiet a while (ASW-24E) and
now having decided to go for the JS1 jet, I consider this a major step
forward in terms of safety.

Make no mistake, none of these engines is an aircraft engine in the
sense used by airplane pilots. You should always expect that it will
fail to start, or worse, quit at the most inappropriate time every
single time you use it. Not doing so is simply foolhardy.

The difference with the JS1 jet (and I imagine the similar shark
installation) is that if the engine does not start, you are not stuck
with a huge profile in the airstream and a glider that is descending
like a rock. You simply flip a switch and about a minute later you are
either climbing or continuing towards a perfectly normal off-field landing.

This is much closer to the idea people have when they buy into a
self-launcher or turbo, only to discover later that the reality is very
different. It is a great sign of progress that now jet and electric
technology are making this much more of a reality.


On 03/06/2015 04:47, wrote:
> They are MODEL engines and are not "man rated" by the FAA. There are several YT vids showing how they are built and assembled. Watch these and then determine if you ever want to put your "skin on the line" using one. By comparison, the Williams FJ-44 is a small TURBOFAN originally built to power US cruise missiles. It had to demonstrate extreme reliability before it was FAA certified and man rated for use on very light business jets. Not to mention it was originally designed to stringent military specs. Bottom line again, these are model TURBOJET engines. Never put your safety/life in a position where their reliability matters.
>

[Dan Marotta]

That was Brett that wrote about the FJ-44, not me.

On 6/3/2015 2:57 PM, Brett wrote:
> Dan Marotta;904892 Wrote:
>> That's what I thought.
>>
>> On 6/2/2015 7:47 PM, wrote:-
>> They are MODEL engines and are not "man rated" by the FAA. There are
>> several YT vids showing how they are built and assembled. Watch these
>> and then determine if you ever want to put your "skin on the line" using
>> one. By comparison, the Williams FJ-44 is a small TURBOFAN originally
>> built to power US cruise missiles. It had to demonstrate extreme
>> reliability before it was FAA certified and man rated for use on very
>> light business jets. Not to mention it was originally designed to
>> stringent military specs. Bottom line again, these are model TURBOJET
>> engines. Never put your safety/life in a position where their
>> reliability matters.-
>>
>> --
>> Dan Marotta
> No Dan, the TJ42 turbine used in the JS1 Revelation has been developed
> from scratch specifically for the sailplane market. They have never been
> used in anything but sailplanes and comprehensive testing has been
> completed for certification. I have had the privilege of visiting the
> factory in Northern Germany and was very impressed with the dedicated
> plant and the professionalism of the staff.
>
> Brett
>
>
>
>

--
Dan Marotta

[[email protected]]

I would expect the QA on these units to be better than that of the typical model turbine. You'll be much less likely to run into a dud here. What is the retail price of this 420N turbine with ECU?

[[email protected]]

"They are MODEL engines and are not "man rated" by the FAA. There are several YT vids showing how they are built and assembled."

A very inappropriate comparison. It's akin to comparing an experimental aircraft with a certified, high capacity transport category aircraft.

The Williams has undergone destructive testing, blade containment testing, is certified for flight into known icing, use on ground, use in rain etc etc.

Using M&D's engine as an example, it has no accessory gearbox so no lubrication; you add extra oil to the fuel like a 2-stroke. It has no electrical system thus no self-sustaining fuel delivery nor command and control. Both of those functions are powered by the battery so it's essential to leave a battery untouched 'for Justin'. It's not approved for ground operation other than maintenance nor for flight in rain. It's a simple, elegant, low weight, low drag thrust source for sustaining. A 'getcha home jet' with only the operating principle as a similarity with Williams and other certified products. And thanks heavens for that! It would be too large, too heavy and too *EXPENSIVE* otherwise.

CJ

[Craig Lowrie]

Chris is exactly right. The HPH Shark Jet uses a industrial
powerplant with over 700 made for UAV / Drone use, so maturity is
high. Field reliability is very good with minimal issues... Normally a
"one-off" re-tuning exercise. You mix turbine oil with JET A1 and
this total-loss approach avoids the needs for a separate lubrication
system. Drag on deployment is not noticable at all. The Engine
management is achieved with a FADEC controller which leaves you
with a single 'Throttle' knob on the panel. HPH have been shipping
the Shark Jet for over 5 years now and into the UK Market (where I
live) for about three years. With "Double-digit" Shark Jets in the UK
I have never had to remove a Jet powerplant yet....

At 05:47 04 June 2015, wrote:
>"They are MODEL engines and are not "man rated" by the FAA.
There are
>seve=
>ral YT vids showing how they are built and assembled."
>
>A very inappropriate comparison. It's akin to comparing an
experimental
>air=
>craft with a certified, high capacity transport category
aircraft.=20
>
>The Williams has undergone destructive testing, blade
containment testing,
>=
>is certified for flight into known icing, use on ground, use in rain
etc
>et=
>c.
>
>Using M&D's engine as an example, it has no accessory gearbox
so no
>lubrica=
>tion; you add extra oil to the fuel like a 2-stroke. It has no
electrical
>s=
>ystem thus no self-sustaining fuel delivery nor command and
control. Both
>=
>of those functions are powered by the battery so it's essential to
leave a
>=
>battery untouched 'for Justin'. It's not approved for ground
operation
>oth=
>er than maintenance nor for flight in rain. It's a simple, elegant,
low
>wei=
>ght, low drag thrust source for sustaining. A 'getcha home jet'
with only
>t=
>he operating principle as a similarity with Williams and other
certified
>pr=
>oducts. And thanks heavens for that! It would be too large, too
heavy and
>=
>too *EXPENSIVE* otherwise.
>
>CJ
>

[[email protected]]

Comparisons aside, my point is simply this, never put yourself in a position where your safety or life is dependent on the operation of one of these small turbines. Several other previous posters agree with me on this.

[Simon Waddell[_2_]]

Well, the same applies to ANY type of glider engine.

When Lord Derby was once asked why he always flew in four-engined aircraft
he replied that it was because there were no six-engined aircraft.


At 13:13 04 June 2015, wrote:
>Comparisons aside, my point is simply this, never put yourself in a
>position where your safety or life is dependent on the operation of one
of
>these small turbines. Several other previous posters agree with me on
this.
>

[son_of_flubber]

On Thursday, June 4, 2015 at 10:00:04 AM UTC-4, Simon Waddell wrote:

> When Lord Derby was once asked why he always flew in four-engined aircraft
> he replied that it was because there were no six-engined aircraft.

And to seque back to glider mounted jet engines... What happens if you mount two of these engines on a glider? Enough thrust for self-launching? Redundancy for sustaining (or to circle back on aborted takeoff)? Twice as many things to break? 2X the cost?

[[email protected]]

Sure. But it's all about fuel. These thing gulp it down. Fueling system in the case of an SL can't be an afterthought. It must be designed into the ship, and would likely mean multiple tanks etc. Probably fuselage and wing tanks. A poorly designed fueling system can lead to all sorts of issues with turbines.

> And to seque back to glider mounted jet engines... What happens if you mount two of these engines on a glider? Enough thrust for self-launching? Redundancy for sustaining (or to circle back on aborted takeoff)? Twice as many things to break? 2X the cost?

[[email protected]]

I agree with Simon - it is crazy to bet your life or glider on the reliability of any type of engine. Personally I am far more concerned about windmill starting draggy 2 stroke turbos than a turbine which why my glider is at the workshop to get its turbine installed today.

It is clear from several posts that some contributors have absolutely no idea of the depth and intensity of the EASA certification process that the three new turbines have had to go through. A post mentioned broken blades so as an example of one test - the M+D jet is planned to have a 500 start and run cycles TBO but, as it was explained to those of us waiting, they had to demonstrate 3 times that number of starts and power runs with cracked blades with no failure - which tests alone took several months to run.

[[email protected]]

> A post mentioned broken blades so as an example of one test - the M+D jet is planned to have a 500 start and run cycles TBO but, as it was explained to those of us waiting, they had to demonstrate 3 times that number of starts and power runs with cracked blades with no failure - which tests alone took several months to run.

That is why I mentioned later, I expect the QA of these turbines to be much better than that of the typical model turbine. Good for them. I do hope they model FOD accurately though. Nice clean lab is one thing...

[J. Nieuwenhuize]

Multiple engines (especially for self-launch) make a lot of sense since price scales neatly with thrust.

2X 230N thrust for a light single-seater, or 2X 800N for an open-class ship would allow a self-launcher with acceptable cruise fuel consumption and self-launch capability.

[[email protected]]

On Thursday, June 4, 2015 at 12:17:49 PM UTC-7, J. Nieuwenhuize wrote:
> Multiple engines (especially for self-launch) make a lot of sense since price scales neatly with thrust.
>
> 2X 230N thrust for a light single-seater, or 2X 800N for an open-class ship would allow a self-launcher with acceptable cruise fuel consumption and self-launch capability.

That's close to what I came up with when investigating for a single seater. You would probably want to carry at least 15 gallons of fuel for the single. Interestingly, when you throw in oil and anti-static, the runtime cost are quite high. You end up finding how economical the old fashioned internal combustion self launch really is. It accomplishes quite a lot with 4 or 5 gallons.

[[email protected]]

>
> That's close to what I came up with when investigating for a single seater. You would probably want to carry at least 15 gallons of fuel for the single. Interestingly, when you throw in oil and anti-static, the runtime cost are quite high. You end up finding how economical the old fashioned internal combustion self launch really is. It accomplishes quite a lot with 4 or 5 gallons.

So in the case of the M&D/JS-1, is it correct to assume the preferred fuel is Jet A? To Jet A, what specific oil and anti-static are added and what is the added ratio?

[[email protected]]

The M+D turbine manual specifies diesel or JetA1 mixed with 4% 2 stroke oil or Aeroshell 560 turbine oil. The tanks are about 42 litres. It gobbles fuel but a one way direct climb and glide retrieve flight will be cheaper than a return road retrieve (by the time you add fuel and vehicle depreciation etc)- but obviously more than a turbo retrieve.

[Jonathan St. Cloud]

Just curious are you putting the jet into a JS-1 or some other aircraft?

[[email protected]]

On Thursday, June 4, 2015 at 5:34:36 PM UTC-4, wrote:
> The M+D turbine manual specifies diesel or JetA1 mixed with 4% 2 stroke oil or Aeroshell 560 turbine oil. The tanks are about 42 litres. It gobbles fuel but a one way direct climb and glide retrieve flight will be cheaper than a return road retrieve (by the time you add fuel and vehicle depreciation etc)- but obviously more than a turbo retrieve.

Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell 560 at $15 a quart that works out to north of $100.00 to fill up the JS-1. Still certainly preferred to landing out a gold-platted crystal slipper 90 miles from home.

So lets round off to $1.00 per M&D jet sustainer mile. Retrieve would be $.65 to $.85 a one-way mile so 180 x $.75 = $135. Certainly not a Solo but still cheaper than a retrieve by road or aero.

[howard banks]

Plus a decent dinner for the retriever ...



On Monday, June 1, 2015 at 4:31:42 AM UTC-6, Jim Pengelly wrote:
> I'm considering ordering a JS1-C TJ with the jet turbine. A potential syndicate partner is concerned about the reliability of jet turbines from a 'will it start' point of view and a repair cost point of view. I imagine electric turbos are going to be more reliable because of the relative simplicity but you can't buy an electric JS1 or 29. Any comments on jet reliability?

[[email protected]]

"Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell 560 at $15 a quart that works out to north of $100 to fill up the JS-1"

Well......you could certainly calculate a worst case scenario like that. But as 11USG of Diesel / 2-stroke (4%) oil mix is flight manual approved, this may be a more commonly employed option.

(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37.

Glider pilots: Tighter than a fish's a....... :P

[Craig Lowrie]

The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell 500. That will
give about 55 minutes cruising at 80-90 knots... The technique is not
climb and glide, rather dolphin flying... pulling up in any residual
energy and in notime you have gained quite a lot of height... It works.
Typically The Shark Jet will do 170km on a tank. The FES version will do
about 100km, whilst the Shark MS (Self Launcher) will do over 300km
on a tank...

Craig

At 08:30 05 June 2015, wrote:
>"Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell
560
>at $15 a quart that works out to north of $100 to fill up the JS-1"
>
>Well......you could certainly calculate a worst case scenario like that.
>But as 11USG of Diesel / 2-stroke (4%) oil mix is flight manual
approved,
>this may be a more commonly employed option.
>
>(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37.
>
>Glider pilots: Tighter than a fish's a....... :P
>

[Dave Walsh]

At 10:10 05 June 2015, Craig Lowrie wrote:
>The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell
500. That will
>give about 55 minutes cruising at 80-90 knots... The
technique is not
>climb and glide, rather dolphin flying... pulling up in any
residual
>energy and in notime you have gained quite a lot of
height... It works.
>Typically The Shark Jet will do 170km on a tank. The FES
version will do
>about 100km, whilst the Shark MS (Self Launcher) will do
over 300km
>on a tank...
>
>Craig
>
Interesting thread but surely if you are proposing to spend
£100K on a jet self-launch the cost of the fuel is a minor
matter? For some people the range will be the overriding
factor, if you are not in this category starting reliability might
be more important.
Jet and two-stroke technology: probably will start?
FES/Electric technology: almost certainly will start?

Ask this question: when pick up a Hoover do you think: Will
it start? When you pick up a two-stroke strimmer or chain
saw do you think: Will it start?

David W

[Dan Marotta]

....And let's not forget to amortize the extra $40-50,000 for acquisition
cost. So, if you land out 40 times during the life of the glider, don't
you also add $1,000+ to the cost of the retrieve?

Neglecting, of course, resale to someone else who doesn't want the
adventure of a field landing.

On 6/4/2015 7:54 PM, wrote:
> On Thursday, June 4, 2015 at 5:34:36 PM UTC-4, wrote:
>> The M+D turbine manual specifies diesel or JetA1 mixed with 4% 2 stroke oil or Aeroshell 560 turbine oil. The tanks are about 42 litres. It gobbles fuel but a one way direct climb and glide retrieve flight will be cheaper than a return road retrieve (by the time you add fuel and vehicle depreciation etc)- but obviously more than a turbo retrieve.
> Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell 560 at $15 a quart that works out to north of $100.00 to fill up the JS-1. Still certainly preferred to landing out a gold-platted crystal slipper 90 miles from home.
>
> So lets round off to $1.00 per M&D jet sustainer mile. Retrieve would be $.65 to $.85 a one-way mile so 180 x $.75 = $135. Certainly not a Solo but still cheaper than a retrieve by road or aero.
>

--
Dan Marotta

[[email protected]]

Neglecting the resale value is a big aspect to neglect. I have only once lost a little money after selling part or all of 9 gliders over the years. Moreover I would far rather have a sustainer than a motorless glider to sell. In Europe e.g Discus BTs and Duo Ts are selling for significantly more than the original cost.

[[email protected]]

I've been working on the jet glider concept for over 10 years. 5 years ago, after a false start with somebody who never delivered what was promised I bought a couple of AMT Titan engines and have almost finished fitting them to my Ventus C 17.6 A fuselage. They are fully retractable. Just some electrical connectors to go and we're ready to do engine runs.
Yes if one engine makes a turbo, two make a self launch and two are better than one even if the installation is a little more difficult. As a slight bonus two Titans of 400N each are in fact cheaper than one Nike of 800N thrust from the same manufacturer.

Fuel consumption: Should get to 2000 feet above ground for around 5 to 6 litres of jet A/jet oil 4.5% mix. Compares favorably with aerotow. Retrieves cheaper than by car, without the outlanding risk and way cheaper than aerotow retrieves. I made a jet performance spreadsheet for takeoff and climb performance. Seems to validate against flying jet gliders. Predicted climb without water ballast nearly 800fpm (SL, standard day at 70% thrust on both engines. Will still climb 280fpm on one and 400fpm on one at 85%. Retrieve range close to 250km. I got 45 litres of fuel and the engines into the A model fuselage without impinging on any space used by pilot or equipment.

Noise: Enough installed thrust and good rate of climb means you're away from the ground quickly. Use airframe shielding and aviation industry noise reduction methods. Existing jet gliders do none of this. I saw and heard Bob Carlton's Super Salto at Avalon in 2009. It wasn't very noisy at all. Neither, I am told, was the Jet Silent he flew a couple of years earlier. I've got a couple of translating ejector nozzles just like the early DC-8 although in this case they are translating in order to minimise engine length for retraction.
Don't forget the noise stops at top of launch, unlike that from a towplane.

Safety: There are two things that can go wrong with the jets. They could catch fire or have a RUD event. I have a fire detection system and Halon fire extinguisher system for the former and 4130 steel around the compressor and turbine sections and the engine compartment is lined with fiberfrax over 8 layers of 170 gram kevlar. The Titan turbine blades are almost the same mass and speed as a .22LR rifle bullet so I took out the .22 and made some samples and tested.
A few years ago a bad batch of compressors made it into model airplane jet world. I gather when they failed some bits dribbled out the front of the engines. I'm not too worried about this.

Operations: Two engines means that launch failures should be rare. You only need to get one out of two running to fly away from a potential outlanding and extending the engines is not a large drag increment. The engines will NEVER be run at 100%. 70% is enough to meet CS22 takeoff at 410Kg and at 500Kg 85%.
Best retrieve range is by running both engines. Should get to 17000 feet above engine start point after a 2000 foot launch.

As for a few other points raised here: The engine in the 304 jet appears to be a Titan with external shielding and I'm told the M&D engine internals are bought from AMT and are the Titan. The Titan seems to be rapidly becoming the standard 400N thrust engine.Certainly seems to be from what I saw. No external shielding which may be why the difficult and expensive EASA certification process just like Draline with the AMT Olympus(8 years.Different starter and case and I'm told, combustor section.
Certification will be the death of this sport.It will make anything vastly more expensive, particularly in a low volume business like soaring.

Anyway, I'm looking forward to having this flying over the next few months and the test flying program should be a lot of fun.

I'm also looking forward to hearing about the flights of the GloW. Should be a fun glider and the electric wheel is a fine idea.

I'll also be testing the new total energy system which completely rejects horizontal gusts and two other new ideas which may change the way glider variometer systems are done.

Mike Borgelt
Borgelt Instruments

[Dan Marotta]

Very informative - thanks!

Please keep us posted on your progress in testing and best of luck.

On 6/5/2015 11:04 PM, wrote:
> I've been working on the jet glider concept for over 10 years. 5 years ago, after a false start with somebody who never delivered what was promised I bought a couple of AMT Titan engines and have almost finished fitting them to my Ventus C 17.6 A fuselage. They are fully retractable. Just some electrical connectors to go and we're ready to do engine runs.
> Yes if one engine makes a turbo, two make a self launch and two are better than one even if the installation is a little more difficult. As a slight bonus two Titans of 400N each are in fact cheaper than one Nike of 800N thrust from the same manufacturer.
>
> Fuel consumption: Should get to 2000 feet above ground for around 5 to 6 litres of jet A/jet oil 4.5% mix. Compares favorably with aerotow. Retrieves cheaper than by car, without the outlanding risk and way cheaper than aerotow retrieves. I made a jet performance spreadsheet for takeoff and climb performance. Seems to validate against flying jet gliders. Predicted climb without water ballast nearly 800fpm (SL, standard day at 70% thrust on both engines. Will still climb 280fpm on one and 400fpm on one at 85%. Retrieve range close to 250km. I got 45 litres of fuel and the engines into the A model fuselage without impinging on any space used by pilot or equipment.
>
> Noise: Enough installed thrust and good rate of climb means you're away from the ground quickly. Use airframe shielding and aviation industry noise reduction methods. Existing jet gliders do none of this. I saw and heard Bob Carlton's Super Salto at Avalon in 2009. It wasn't very noisy at all. Neither, I am told, was the Jet Silent he flew a couple of years earlier. I've got a couple of translating ejector nozzles just like the early DC-8 although in this case they are translating in order to minimise engine length for retraction.
> Don't forget the noise stops at top of launch, unlike that from a towplane.
>
> Safety: There are two things that can go wrong with the jets. They could catch fire or have a RUD event. I have a fire detection system and Halon fire extinguisher system for the former and 4130 steel around the compressor and turbine sections and the engine compartment is lined with fiberfrax over 8 layers of 170 gram kevlar. The Titan turbine blades are almost the same mass and speed as a .22LR rifle bullet so I took out the .22 and made some samples and tested.
> A few years ago a bad batch of compressors made it into model airplane jet world. I gather when they failed some bits dribbled out the front of the engines. I'm not too worried about this.
>
> Operations: Two engines means that launch failures should be rare. You only need to get one out of two running to fly away from a potential outlanding and extending the engines is not a large drag increment. The engines will NEVER be run at 100%. 70% is enough to meet CS22 takeoff at 410Kg and at 500Kg 85%.
> Best retrieve range is by running both engines. Should get to 17000 feet above engine start point after a 2000 foot launch.
>
> As for a few other points raised here: The engine in the 304 jet appears to be a Titan with external shielding and I'm told the M&D engine internals are bought from AMT and are the Titan. The Titan seems to be rapidly becoming the standard 400N thrust engine.Certainly seems to be from what I saw. No external shielding which may be why the difficult and expensive EASA certification process just like Draline with the AMT Olympus(8 years.Different starter and case and I'm told, combustor section.
> Certification will be the death of this sport.It will make anything vastly more expensive, particularly in a low volume business like soaring.
>
> Anyway, I'm looking forward to having this flying over the next few months and the test flying program should be a lot of fun.
>
> I'm also looking forward to hearing about the flights of the GloW. Should be a fun glider and the electric wheel is a fine idea.
>
> I'll also be testing the new total energy system which completely rejects horizontal gusts and two other new ideas which may change the way glider variometer systems are done.
>
> Mike Borgelt
> Borgelt Instruments

--
Dan Marotta

[jfitch]

On Friday, June 5, 2015 at 3:15:06 AM UTC-7, Craig Lowrie wrote:
> The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell 500. That will
> give about 55 minutes cruising at 80-90 knots... The technique is not
> climb and glide, rather dolphin flying... pulling up in any residual
> energy and in notime you have gained quite a lot of height... It works.
> Typically The Shark Jet will do 170km on a tank. The FES version will do
> about 100km, whilst the Shark MS (Self Launcher) will do over 300km
> on a tank...
>
> Craig
>
> At 08:30 05 June 2015, wrote:
> >"Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell
> 560
> >at $15 a quart that works out to north of $100 to fill up the JS-1"
> >
> >Well......you could certainly calculate a worst case scenario like that.
> >But as 11USG of Diesel / 2-stroke (4%) oil mix is flight manual
> approved,
> >this may be a more commonly employed option.
> >
> >(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37.
> >
> >Glider pilots: Tighter than a fish's a....... :P
> >

For reference, an ASH26E uses about 2 liters for a warm up and climb to 2500 ft agl, and will do 680 Km on its 16 liter tank (according to the book - never had a retrieve that long!). To do that you climb to altitude limits then fold the engine and glide, and repeat as needed. Is the climb performance on a jet significantly better so that the climb and glide technique improves retrieve range over a level cruise?

[Craig Lowrie]

Climb and glide with the Jet is NOT optimal...

The best speed for the Jet engine is probably over 200 knots (!)....
and whilst this is not possible, the faster the better... so after
briefly climbing away from a field, it is better to accelerate to 80-90
knots and then dolphin-fly, varying speed in accordance with any
residual lift (these is always some)... This technique will produce
the best range...

Craig

At 19:02 06 June 2015, jfitch wrote:
>On Friday, June 5, 2015 at 3:15:06 AM UTC-7, Craig Lowrie
wrote:
>> The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell 500.
That will=20
>> give about 55 minutes cruising at 80-90 knots... The technique
is not=20
>> climb and glide, rather dolphin flying... pulling up in any
residual=20
>> energy and in notime you have gained quite a lot of height... It
works. =
>=20
>> Typically The Shark Jet will do 170km on a tank. The FES
version will do=
>=20
>> about 100km, whilst the Shark MS (Self Launcher) will do over
300km=20
>> on a tank...
>>=20
>> Craig
>>=20
>> At 08:30 05 June 2015, wrote:
>> >"Gobble as well as gulp...with Jet A at +/- $5 a gallon and
AeroShell=20
>> 560
>> >at $15 a quart that works out to north of $100 to fill up the
JS-1"
>> >
>> >Well......you could certainly calculate a worst case scenario
like
>that.=
>=20
>> >But as 11USG of Diesel / 2-stroke (4%) oil mix is flight
manual=20
>> approved,
>> >this may be a more commonly employed option.=20
>> >
>> >(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37. =20
>> >
>> >Glider pilots: Tighter than a fish's a....... :P
>> >
>
>For reference, an ASH26E uses about 2 liters for a warm up and
climb to
>250=
>0 ft agl, and will do 680 Km on its 16 liter tank (according to the
book -
>=
>never had a retrieve that long!). To do that you climb to altitude
limits
>t=
>hen fold the engine and glide, and repeat as needed. Is the climb
>performan=
>ce on a jet significantly better so that the climb and glide
technique
>impr=
>oves retrieve range over a level cruise?
>

[J. Nieuwenhuize]

Op zaterdag 6 juni 2015 21:02:52 UTC+2 schreef jfitch:
For reference, an ASH26E uses about 2 liters for a warm up and climb to 2500 ft agl, and will do 680 Km on its 16 liter tank (according to the book - never had a retrieve that long!). To do that you climb to altitude limits then fold the engine and glide, and repeat as needed. Is the climb performance on a jet significantly better so that the climb and glide technique improves retrieve range over a level cruise?

Yes. The higher the thrust/weight ratio is, the more it pays off. Best CLIMB speed for example for a 450 kg ship and a 800N jet is way above 100 kts.

For highter thrust/weight ratio's, fuel efficiency goes up too; a dolphining flight can get similar mileage to a decent car, even with the typical fuel burn of such a jet (70 kg/hr for the 800N AMT).

[[email protected]]

I have seen various slightly different graphs from JS for ways of using their jet but consistently they predict the greatest theoretical range being from a full power climb at around 80 knots and then glide.

Next best is the economical cruise at about 75,000 rpm and around 75-80 knots - similar to the HpH scenario but JS haven't included the dolphining effect. All flight traces I have found of the JS1 jet being used for real life retrieves seem to show it being used for slow climb and cruise around 75 knots.

I am not sure if including extra range from dolphining gives a valid comparison as there is no stated model of the amount of dolphin-worthy lift being flown through. Also I would have thought that if there was enough lift to gain significant range from dolphining I would turn off the jet and get proper netto and STF info to dolphin efficiently - bearing in mind that these computations rely on the polar in the computer being the same as the glider which it clearly isn't with any engine running (even without considering prop/jetwash effects on the fin probe).

[[email protected]]

What range does JS predict when using these techniques?


On Sunday, June 7, 2015 at 3:12:48 AM UTC-7, wrote:

> I have seen various slightly different graphs from JS for ways of using their jet but consistently they predict the greatest theoretical range being from a full power climb at around 80 knots and then glide.
>
> Next best is the economical cruise at about 75,000 rpm and around 75-80 knots - similar to the HpH scenario but JS haven't included the dolphining effect. All flight traces I have found of the JS1 jet being used for real life retrieves seem to show it being used for slow climb and cruise around 75 knots.
>

[OG]

Some comments from actual experience:
I have flown both self launching and sustainer gliders (Schemmp & AS), and now own a JS with turbine. I have no experience with the FES, although I have seen it ground run. For this post I will mostly ignore the FES, although I think it is an excellent system, save for the minimal drag which is a large concern for contest pilots. Plus, our national electicity supplier are all out of electricity and options, so charging might be difficult at times 😄 ( just kidding)

Operation:
The jet is by far the easiest to deploy, start, run, shut down and retract. It is a simple 3 step process. Turn on the master switch, switch the turbine to run, wait for turbine to spool up, and add power by turning a knob, all on one 57mm LCD instrument. The software can actually spool up the turbine to max rpm automatically, elliminating step 3. Shutting down is equally effortless. Switch off, and the controller does the rest. It waits for the turbine to cool, and then retracts automatically. Once retracted, you can turn the engine master switch off.
Safety: I have deployed the jet sucessfully from 150' agl (thats feet agl). Normally, I switch the master on at about 1000' agl. I extract the engine at 600', but do not start it yet. At 250' agl I switch on the jet, and it is at idle rpm at 150-160' agl.
Compared to the AS wankel engine, which I would start that at 600'. The solo sustainer I would normally start at 1000' agl. Both the wankel and turbo engines have a significantly higher workload than the jet.
In all of these scenarios I obviously have a landing field available in case of a failed start. I have had failed starts, and subsequent outlandings, with all three systems. No system is 100% reliable.
Initially (I had one of the early installations ) the reliability was about 60%. M&D and JS have however ironed out the initial problems and reliability issues (expected with any new system). I dont keep exact track, but I have not had a failed start or problem for the last year, except a glowplug glitch on the ground before flight for the last 18 months, so reliabilty is now a small worry.
Use
I have used the jet 5 times now in the last 100 cross country flights, with the longest retrieve about 220km straight line through dead air, I climbed from about 1000' agl in light rain, flying at about 70kts ias. I continued climbing up to about 11000' amsl, or 6000' agl and switched off the jet. I burned 30 liters of fuel. I estimate that a 380-400km range is possible in dead air. The rain stopped after the first 5km.
General:
Maintenance is all but non existant, apart from the ocasional wipe off to get rid of dust, and a visual pre flight inspection. I had the actuator that extends the engine replaced (under guarantee). Refueling is very easy. I prefer using Jet A1, as I think it is a more efficient fuel, and it smells better 😄. The fuel filter gets cleaned or replaced during the annual inspection.
Noise in the cockpit is not intrusive, even when wearing no earplugs or a headset. The radio can be heard clearly through the normal speakers, as can the vario. Noise on the ground during a flypast is less than the traditional internal combustion engine. It gets noisy when doing a stationary ground runs, but no more than a prop driven self launcher.
When the jet has not been in use for an extended period, a ground start before flight is advisable to purge the fuel supply of air, ensuring an immediate start in the air.
As the glow plug and fuel pump needs constant current during operation, it is advisable to have your battery charged up.
The jet goes from master on to full power in 45 seconds. Idle rpm is 30 000 rpm, and full power delivers just under 100k rpm. I normally limit the rpm to 95k. At 95k rpm the fuel burn is 40liters per hour, and fuel capacity is 42 liters. Fuel burn drops to about 35 liters per hour at 9000' amsl. Exhaust gas temprerature is about 650 deg celcius at full power. Temperature change on the vertical tail skin is minimal, even on the ground as the engine is slightly offset.
On the test aircraft, during the endurance test, which was flown for an hour above 20 000' amsl and at 110 000 rpm continously, a blade did separate from the rotor. The blade was contained in the housing with no other damage to the engine or glider. This specific engine had run all the certification tests before throwing the blade. I dont know how many hours it had, but it was significant.
I can honesly say this is the best system if you want to avoid landouts. The airfield I fly from mostly has a tug available, so I dont need a self launcher. Apart from the simplicity and efficiency of the jet, the biggest factor is the sheer joy of playing around with the jet running.

[[email protected]]

OG--thanks for your input.

What is Standard Operating Procedure regarding leaving jet fuel in tanks between flight? Should you always leave the tanks full or do you pump all the fuel out after flight and refill before next possible use?

Once you buy Jet A, how long would you keep the fuel before you would consider it "bad"?

What is Jonkers/M&D warranty regarding jet and ECU?

[OG]

I leave the fuel in the tank, but replace it every 3 months, should it not be used in that period. I am not sure what Jet A1 specs say about shelf life, but I think this is about right.
Seeing as the jet is still in evaluation/developmental phase, I am not actually sure what the warranty is. That being said JS/M&D stands behind the product. My actuator was replaced at no cost. Barring obvious misuse/abuse I am sure they will be more than reasonable with any latent defect. But I dont speak for either of them, so dont quote me😉

[[email protected]]

On Sunday, June 7, 2015 at 9:28:54 PM UTC+1, OG wrote:
> I leave the fuel in the tank, but replace it every 3 months, should it not be used in that period. I am not sure what Jet A1 specs say about shelf life, but I think this is about right.
> Seeing as the jet is still in evaluation/developmental phase, I am not actually sure what the warranty is. That being said JS/M&D stands behind the product. My actuator was replaced at no cost. Barring obvious misuse/abuse I am sure they will be more than reasonable with any latent defect. But I don't speak for either of them, so dont quote me😉

There is a 2012 UK General Aviation Safety Information Leaflet that advises a "shelf life" of 3 months for Avgas and 6 months for Jet A1. It advises keeping tanks 90% full to reduce deterioration or water contamination.

[[email protected]]

On Sunday, June 7, 2015 at 4:15:05 PM UTC+10, Craig Lowrie wrote:
> Climb and glide with the Jet is NOT optimal...


Actually my spreadsheet says that climb/glide is the optimal method even with the jet. I was somewhat surprised by this as with piston retractable engined motorgliders it obviously is as the L/D with engine extended is so bad.. Airplane range is a function of a number of things and L/D is a big one (see Breguet range equation). The L/D with the extended jets would seem to be much better but you don't operate it at best L/D for the climb as the jet best rate of climb speed is very much higher than with a piston engine (thrust drop off with speed is much less and power to aircraft = forward speed x thrust). The single engine jet turbos have much lower thrust to weight than a self launcher so use most of the thrust to stay in level flight particularly if you throttle back to be easier on the jet, so climb/glide probably doesn't work so well there.
There is another consideration and that is the specific fuel consumption of the engine. Jets don't do deep throttling well and 70% is about as low as you want to go before the SFC starts to go bad. This is a good reason for two engines on the self launcher. Just shut down and retract one if you need to fly level because of airspace or meteorological considerations.

One benefit of the high climb airspeed is that you aren't waffling around in a high drag configuration near the stall.

Unless you have a very high thrust/weight, 200 knots is way above the best rate of climb speed for a glider.

To make CS22 takeoff performance you a a T/W of about 0.13 to 0.14. So to let you run the engine(s) at say 70% for takeoff and climb the nominal installed T/W needs to be about 0.18 to 0.20 . This gives reasonable takeoff distance with margin over CS22 and an excellent climb rate at around 100 knots for a modern glider.

As my Ventus has the motorglider CM wings I chose to put the fuel in the fuselage rather than in the wings. Operationally easier when operating out of trailer and no mods to the wings. Weights and speeds are all within the Ventus CM envelope.

Whilst a piston self launcher will use less fuel the jet is comparable to aerotow for launch. Not surprising as the efficiency of the jet is 10 to 11% of fuel energy and SO IS A PAWNEE doing an aerotow.

The jet compares very favorably with a car retrieve also and flying back home in your jet is way more fun than a car retrieve.

I'm not the least little bit interested in retrieve only jets. As a friend of mine once said about the turbo concept: 10% of the utility and 90% of the trouble of a self launcher.

[Bruce Hoult]

On Monday, June 8, 2015 at 12:44:48 PM UTC+3, wrote:
> On Sunday, June 7, 2015 at 4:15:05 PM UTC+10, Craig Lowrie wrote:
> > Climb and glide with the Jet is NOT optimal...
>
>
> Actually my spreadsheet says that climb/glide is the optimal method even with the jet. I was somewhat surprised by this as with piston retractable engined motorgliders it obviously is as the L/D with engine extended is so bad.

I'm glad someone else worked this out. You're pretty clean with a jet, but it's most efficient at as close to Vne as you dare to go, so your L/D is probably only 15 - 20, whereas once you shut the jet off you'll want to fly at a speed where your L/D is 40+ (well, 30+ anyway).

Running a jet to sustain level flight at 60 - 80 knots is silly, unless that's all the thrust it has, but even then a slightly more powerful jet that lets you go faster will use less fuel.

[Bruce Hoult]

On Saturday, June 6, 2015 at 8:04:07 AM UTC+3, wrote:
> I've been working on the jet glider concept for over 10 years.

I find it interesting to compare against this post I made on rocket engine launch, just over 15 years ago!

https://groups.google.com/forum/#!original/rec.aviation.soaring/LThQHAfU8nI/r3mTaAhMSDcJ


> Yes if one engine makes a turbo, two make a self launch and two are better than one even if the installation is a little more difficult. As a slight bonus two Titans of 400N each are in fact cheaper than one Nike of 800N thrust from the same manufacturer.

There, I worked out that 50 kgf (490 N) was not enough for adequate launch performance, but 100 kgf (980 N) looked pretty nice. 160 kg (1570 N) would be nice if you could get it, but much over that starts to make everything just happen waaay too fast.

So your 400 N and 800 N are in the same ballpark I worked out waaay back when.

[[email protected]]

On Monday, June 8, 2015 at 11:44:48 AM UTC+2, wrote:
> I'm not the least little bit interested in retrieve only jets. As a friend of mine once said about the turbo concept: 10% of the utility and 90% of the trouble of a self launcher.

It's rather 10% of the trouble, at least with the many selflaunchers and turbos I know of. A Solo 2350 can run many years with minimal maintenance and no major issues, something that doesn't seem to happen with selflaunchers very often...

[Tango Whisky]

Am Montag, 8. Juni 2015 14:25:59 UTC+2 schrieb Bruce Hoult:
> On Saturday, June 6, 2015 at 8:04:07 AM UTC+3, wrote:
> > I've been working on the jet glider concept for over 10 years.
>
> I find it interesting to compare against this post I made on rocket engine launch, just over 15 years ago!
>
> https://groups.google.com/forum/#!original/rec.aviation.soaring/LThQHAfU8nI/r3mTaAhMSDcJ
>
>
> > Yes if one engine makes a turbo, two make a self launch and two are better than one even if the installation is a little more difficult. As a slight bonus two Titans of 400N each are in fact cheaper than one Nike of 800N thrust from the same manufacturer.
>
> There, I worked out that 50 kgf (490 N) was not enough for adequate launch performance, but 100 kgf (980 N) looked pretty nice. 160 kg (1570 N) would be nice if you could get it, but much over that starts to make everything just happen waaay too fast.
>
> So your 400 N and 800 N are in the same ballpark I worked out waaay back when.

For a piston engine, static thrust in daN is about 2x installed horsepower.
My Ventus cM has 30 hp, and 60 daN is on the low side for takeoff (I know what I'm talking about...). The V2CM and DG800 have 50 hp installed, and from watching them taking off I'd think that 100 daN is on the generous side.

A also was thinking along the lines of Mike Borgelt that in case my Solo engine died on me, two Titan engines would be a nice fit. Space would not be a problem; tank capacity would probably be limited by max mass of no-lifting parts.

Bert TW

[bumper[_4_]]

On Sunday, June 7, 2015 at 12:29:34 PM UTC-7, wrote:
> OG--thanks for your input.
>
>
> Once you buy Jet A, how long would you keep the fuel before you would consider it "bad"?

Self launch and turbo gliders sometimes have low fuel throughput, and this gives HUMs (hydrocarbon utilizing microbes) a chance to thrive in the fuel/water interface - and there will always be some moisture. HUMs have been an issue for Stemme and Schleicher owners, as the HUMs excrete acid that can corrode metal parts and they attack fuel lines and clog filters.

The shelf life of Avgas (at least a year) and Jet-A (even longer) in the US is not the issue, it's keeping the microbes from contaminating fuel and fuel system. Many of us use BioborJF (the JF is for jet fuel for which Biobor is certified - though it works in gasoline too). It only takes 4 ml per 5 gallons for initial dose and then 2 ml per 5 gallons after that.

Note that Biobor also has a "MD" and "EB" version for diesel and ethanol laced fuels, though the "JF" version is the only version I'm aware of that includes antimicrobial ingredients.

[[email protected]]

On Monday, June 8, 2015 at 4:44:10 PM UTC+1, bumper wrote:
> On Sunday, June 7, 2015 at 12:29:34 PM UTC-7, wrote:
> > OG--thanks for your input.
> >
> >
> > Once you buy Jet A, how long would you keep the fuel before you would consider it "bad"?
>
> Self launch and turbo gliders sometimes have low fuel throughput, and this gives HUMs (hydrocarbon utilizing microbes) a chance to thrive in the fuel/water interface - and there will always be some moisture. HUMs have been an issue for Stemme and Schleicher owners, as the HUMs excrete acid that can corrode metal parts and they attack fuel lines and clog filters.
>
> The shelf life of Avgas (at least a year) and Jet-A (even longer) in the US is not the issue, it's keeping the microbes from contaminating fuel and fuel system. Many of us use BioborJF (the JF is for jet fuel for which Biobor is certified - though it works in gasoline too). It only takes 4 ml per 5 gallons for initial dose and then 2 ml per 5 gallons after that.
>
> Note that Biobor also has a "MD" and "EB" version for diesel and ethanol laced >fuels, though the "JF" version is the only version I'm aware of that includes >antimicrobial ingredients.

That is very interesting Bumper but unfortunately I can't find BioborJF on sale in the UK. I find an 2008 UK magazine review of marine diesel products that has a reference to legislation that meant that "any product which claims a controlling effect on microorganisms should be registered with the Health and Safety Executive (HSE) and by 31 October 2008 they will need a technical dossier confirming the product is safe, environmentally acceptable and effective. Because registration involves significant expense, some biocides such as Biobor JF have been pulled from the market".

Also some US sellers on Ebay or Amazon say they cannot ship it to the UK.

John Galloway

[[email protected]]

I've never had a problem with microbes/algae. But after using kero/Jet-A and diesel, I just use Chevron diesel now and never had a problem since my engines are rated for all these fuels. Don't forget diesel give you a bit better performance over kero/Jet-A.

[[email protected]]

On Sunday, June 7, 2015 at 6:39:22 PM UTC+1, OG wrote:
> Some comments from actual experience:
> I have flown both self launching and sustainer gliders (Schemmp & AS), and now own a JS with turbine. I have no experience with the FES, although I have seen it ground run. For this post I will mostly ignore the FES, although I think it is an excellent system, save for the minimal drag which is a large concern for contest pilots. Plus, our national electicity supplier are all out of electricity and options, so charging might be difficult at times 😄 ( just kidding)
>
> Operation:
> The jet is by far the easiest to deploy, start, run, shut down and retract. It is a simple 3 step process. Turn on the master switch, switch the turbine to run, wait for turbine to spool up, and add power by turning a knob, all on one 57mm LCD instrument. The software can actually spool up the turbine to max rpm automatically, elliminating step 3. Shutting down is equally effortless. Switch off, and the controller does the rest. It waits for the turbine to cool, and then retracts automatically. Once retracted, you can turn the engine master switch off.
> Safety: I have deployed the jet sucessfully from 150' agl (thats feet agl). Normally, I switch the master on at about 1000' agl. I extract the engine at 600', but do not start it yet. At 250' agl I switch on the jet, and it is at idle rpm at 150-160' agl.
> Compared to the AS wankel engine, which I would start that at 600'. The solo sustainer I would normally start at 1000' agl. Both the wankel and turbo engines have a significantly higher workload than the jet.
> In all of these scenarios I obviously have a landing field available in case of a failed start. I have had failed starts, and subsequent outlandings, with all three systems. No system is 100% reliable.
> Initially (I had one of the early installations ) the reliability was about 60%. M&D and JS have however ironed out the initial problems and reliability issues (expected with any new system). I dont keep exact track, but I have not had a failed start or problem for the last year, except a glowplug glitch on the ground before flight for the last 18 months, so reliabilty is now a small worry.
> Use
> I have used the jet 5 times now in the last 100 cross country flights, with the longest retrieve about 220km straight line through dead air, I climbed from about 1000' agl in light rain, flying at about 70kts ias. I continued climbing up to about 11000' amsl, or 6000' agl and switched off the jet.. I burned 30 liters of fuel. I estimate that a 380-400km range is possible in dead air. The rain stopped after the first 5km.
> General:
> Maintenance is all but non existant, apart from the ocasional wipe off to get rid of dust, and a visual pre flight inspection. I had the actuator that extends the engine replaced (under guarantee). Refueling is very easy. I prefer using Jet A1, as I think it is a more efficient fuel, and it smells better 😄. The fuel filter gets cleaned or replaced during the annual inspection.
> Noise in the cockpit is not intrusive, even when wearing no earplugs or a headset. The radio can be heard clearly through the normal speakers, as can the vario. Noise on the ground during a flypast is less than the traditional internal combustion engine. It gets noisy when doing a stationary ground runs, but no more than a prop driven self launcher.
> When the jet has not been in use for an extended period, a ground start before flight is advisable to purge the fuel supply of air, ensuring an immediate start in the air.
> As the glow plug and fuel pump needs constant current during operation, it is advisable to have your battery charged up.
> The jet goes from master on to full power in 45 seconds. Idle rpm is 30 000 rpm, and full power delivers just under 100k rpm. I normally limit the rpm to 95k. At 95k rpm the fuel burn is 40liters per hour, and fuel capacity is 42 liters. Fuel burn drops to about 35 liters per hour at 9000' amsl. Exhaust gas temprerature is about 650 deg celcius at full power. Temperature change on the vertical tail skin is minimal, even on the ground as the engine is slightly offset.
> On the test aircraft, during the endurance test, which was flown for an hour above 20 000' amsl and at 110 000 rpm continously, a blade did separate from the rotor. The blade was contained in the housing with no other damage to the engine or glider. This specific engine had run all the certification tests before throwing the blade. I dont know how many hours it had, but it was significant.
> I can honesly say this is the best system if you want to avoid landouts. The airfield I fly from mostly has a tug available, so I dont need a self launcher. Apart from the simplicity and efficiency of the jet, the biggest factor is the sheer joy of playing around with the jet running.

Hi Oscar,

A very helpful post but you mention "at 95k rpm the fuel burn is 40liters per hour".

Is it not about 60 litres per hour at that rpm and the potential range calculation correspondingly reduced?

John Galloway

[Ramy[_2_]]

There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
So much for jet reliability. Apparently can't trust them either.
I heard of at least 3 landouts of motorgliders recently.
Hopefully electric motors will be more reliable.

Ramy

[John Galloway[_1_]]

At 20:47 06 July 2015, Ramy wrote:
>There was a recent landout of a brand new JS1 in the middle of nowhere
near
>Hobbs during the contest due to jet failure. Multiple attempts were made
to
>start it.
>So much for jet reliability. Apparently can't trust them either.
>I heard of at least 3 landouts of motorgliders recently.
>Hopefully electric motors will be more reliable.
>
>Ramy

It would be interesting to know why that jet didn't start and also whether

it had been run in the air or on the ground before the task that day.
The
jet glider pilots I have spoken to don't seem to routinely do test runs but
I
can imagine simple problems that could be found - e.g. airlock in the fuel

line after trailering. The JS1 jet overhaul interval is going to be based
on
number of starts rather than hours so perhaps that is a disincentive. In
22 years I never intentionally took a 2 stroke turbo cross-country without

doing a test run before starting the task. I occasionally uncovered
starting
problems that were easily fixed back on the ground. Any time the turbo
didn't start there was always a straightforward reason for it. At least
the
jets can be started on the ground for a few seconds so a problem could be
found found before taking a launch rather than afterwards.

John Galloway

[Sean Franke]

On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
> There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
> So much for jet reliability. Apparently can't trust them either.
> I heard of at least 3 landouts of motorgliders recently.
> Hopefully electric motors will be more reliable.
>
> Ramy

HpH 304 Shark jet sustainer owners have reported a very reliable jet start. HpH uses a TBS J40 Engine.

Sean Franke

[Ramy[_2_]]

I don't have more details except that the jet engine was later removed and sent for repair.

Ramy

[[email protected]]

On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
> There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
> So much for jet reliability. Apparently can't trust them either.
> I heard of at least 3 landouts of motorgliders recently.
> Hopefully electric motors will be more reliable.
>
> Ramy

May be a good thing it didn't light after multiple start attempts.. it's usually the condition under which you'll get a wet start. May not be a big deal in this configuration but depends how much residual fuel was there.

[Steve Leonard[_2_]]

On Monday, July 6, 2015 at 5:21:03 PM UTC-5, Ramy wrote:
> I don't have more details except that the jet engine was later removed and sent for repair.
>
> Ramy

The failure to start was not at Hobbs, but flying from Moriarty before going to Hobbs for the contest. The engine removal happened at Hobbs after troubleshooting by swapping parts from one plane to another.

Steve Leonard

[John Galloway[_1_]]

At 14:34 07 July 2015, Steve Leonard wrote:
>On Monday, July 6, 2015 at 5:21:03 PM UTC-5, Ramy wrote:
>> I don't have more details except that the jet engine was later
removed
>and sent for repair.
>>
>> Ramy
>
>The failure to start was not at Hobbs, but flying from Moriarty before
>going to Hobbs for the contest. The engine removal happened at Hobbs
after
>troubleshooting by swapping parts from one plane to another.
>
>Steve Leonard
>

Steve, was a diagnosis made as a result of the troubleshooting?

John Galloway

[Steve Leonard[_2_]]

On Tuesday, July 7, 2015 at 11:45:05 AM UTC-5, John Galloway wrote:
> At 14:34 07 July 2015, Steve Leonard wrote:
> >On Monday, July 6, 2015 at 5:21:03 PM UTC-5, Ramy wrote:
> >> I don't have more details except that the jet engine was later
> removed
> >and sent for repair.
> >>
> >> Ramy
> >
> >The failure to start was not at Hobbs, but flying from Moriarty before
> >going to Hobbs for the contest. The engine removal happened at Hobbs
> after
> >troubleshooting by swapping parts from one plane to another.
> >
> >Steve Leonard
> >
>
> Steve, was a diagnosis made as a result of the troubleshooting?
>
> John Galloway

You would need to talk with Bill Gawthrop and Dave Coggins about what was determined.

Steve

[2G]

On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
> There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
> So much for jet reliability. Apparently can't trust them either.
> I heard of at least 3 landouts of motorgliders recently.
> Hopefully electric motors will be more reliable.
>
> Ramy

I am interested in knowing which type of motorgliders and was a start attempted vs landing because there was insufficient altitude for a restart. My experience is that engine restart is very reliable because you have the benefit of windmilling to spin the prop faster (I know nothing about the jets). Most failures to start are the result of pilot error (myself included). But everything mechanical is subject to failure (that includes towplanes!).

Tom

[Charlie M. (UH & 002 owner/pilot)]

On Tuesday, July 7, 2015 at 4:46:43 PM UTC-4, 2G wrote:
> On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
> > There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
> > So much for jet reliability. Apparently can't trust them either.
> > I heard of at least 3 landouts of motorgliders recently.
> > Hopefully electric motors will be more reliable.
> >
> > Ramy
>
> I am interested in knowing which type of motorgliders and was a start attempted vs landing because there was insufficient altitude for a restart. My experience is that engine restart is very reliable because you have the benefit of windmilling to spin the prop faster (I know nothing about the jets). Most failures to start are the result of pilot error (myself included). But everything mechanical is subject to failure (that includes towplanes!).
>
> Tom

It's a frikkin jet..... not much "windmilling" going on within VNE of the glider........

Guess you didn't read most of the thread...... ;-)

[[email protected]]

And.......they are still derivatives of model engines made by model engine manufacturers. We're not talking GE or Pratt & Whitney here

[[email protected]]

http://youtu.be/oACMOuSoHQc

[JS]

From the Jonker website:
"M&D decided that rather than convert a model aircraft jet turbine into a glider sustainer, it would be better to develop and certificate a new engine."
I've been on an airliner that has had a major in-flight system failure. It happens to everyone.
Jim

On Tuesday, July 7, 2015 at 7:07:20 PM UTC-7, wrote:
> And.......they are still derivatives of model engines made by model engine manufacturers. We're not talking GE or Pratt & Whitney here

[ND]

On Monday, June 1, 2015 at 6:31:42 AM UTC-4, Jim Pengelly wrote:
> I'm considering ordering a JS1-C TJ with the jet turbine. A potential syndicate partner is concerned about the reliability of jet turbines from a 'will it start' point of view and a repair cost point of view. I imagine electric turbos are going to be more reliable because of the relative simplicity but you can't buy an electric JS1 or 29. Any comments on jet reliability?

everyone's complaining about "that engine not being so reliable", "i don't know if i'd trust that MODEL engine", "what if it doesn't start?", "but you have to dive to get it going" and i'm over here flying a pure glider like: ᕙ(⇀‿↼‶)ᕗ

we reallllly hate farmers apparently. a farmer gave me a sandwich and a beer once. dude was solid.

Remember that the drag penalty with an extracted jet is minimal. Also keep in mind that if you are going to step into any glider, that there is a chance you won't be landing it on a runway no matter what you've got. Lastly you shouldn't put yourself where you need the engine in order to not make junk. it's a convenience, not a silver bullet.

[Jonathan St. Cloud]

Just so you know the ASG-29Es has an electric start, no need to dive to start. 12 seconds to extend and start, much easier than the ASG-29E.

On Wednesday, July 8, 2015 at 6:16:50 AM UTC-7, ND wrote:

>
> everyone's complaining about "that engine not being so reliable", "i don't know if i'd trust that MODEL engine", "what if it doesn't start?", "but you have to dive to get it going" and i'm over here flying a pure glider like: ᕙ(⇀‿↼‶)ᕗ

[OG]

Sorry John, havent been on the forum for some time. The 40l l/h is what the JDU displayed, and it seems to be reasonably accurate. Also, I dont run it at full throttle, but rather at about 90k RPM.

[Jonathan St. Cloud]

What is the weight of the JS1 jet and 45 minutes of fuel over the weight of the un-engined version.

[[email protected]]

On Tuesday, July 14, 2015 at 2:48:49 AM UTC+1, Jonathan St. Cloud wrote:
> What is the weight of the JS1 jet and 45 minutes of fuel over the weight of the un-engined version.

+49.7kg - of which 35.2 kg is fuel. Add to that 7 kg additional nose ballast for a 90 kg cockpit load and the wingloading still low at 38.7kg/m2 in 21m and 41.6 in 18m.

[[email protected]]

On Monday, July 13, 2015 at 8:51:53 PM UTC+1, OG wrote:
> Sorry John, havent been on the forum for some time. The 40l l/h is what the JDU displayed, and it seems to be reasonably accurate. Also, I dont run it at full throttle, but rather at about 90k RPM.

Thanks Oscar that is very interesting information.