best self-launcher propulsion system?

I am curious what group members with experience with self-launchers
regard as the best propulsion system (currently) in terms of in-flight
restart reliability, maintenance, safety, and other operational
factors (e.g., vibration). Of course the electric Antares might win
on all counts except for range, but it is out of my price league.

thanks,

Key

Well, if the Euro keeps declining perhaps you
can afford an Antares (~1.27 today).
The range is more than you might expect,
as you don't need to climb as high before
shutdown as other machines, leaving bigger
reserve (subject to lift convenient to launch).
Good luck,
Best Regards, Dave "YO electric"

PS: My Antares has never failed to air-start
(unlike my previous machine). ~12 seconds
from gliding to power with no fuss.

On Jan 10, 5:21*pm, Dave Nadler wrote:
Well, if the Euro keeps declining perhaps you
can afford an Antares (~1.27 today).
The range is more than you might expect,
as you don't need to climb as high before
shutdown as other machines, leaving bigger
reserve (subject to lift convenient to launch).
Good luck,
Best Regards, Dave "YO electric"

PS: My Antares has never failed to air-start
(unlike my previous machine). ~12 seconds
from gliding to power with no fuss.

Don't need to climb as high?? because?
Engine stows quicker reducing time of drag exposure?
No need to keep the bay doors open for engine cooling reducing drag
exposure?

Please explain.

T

A 2-stroke is a 2-stroke is a 2-stroke.

I own one outright, have a share in another, have looked closely at many
others and quizzed many other owners. If you're a fellow-member of the
self-launch owners club they'll talk honestly because they think you
won't rat on them - one day you'll have to sell one too. All of the
engines, as engines, are about equally reliable. The problem with all
of them is that a 2-stroke continually tries to vibrate everything
attached to it to death. Fuel line joiners, electrical wiring,
thermocouples, temperature transmitters, starters, flywheels,
alternators, magnetos, ignition boxes, fuel pumps, carburettors, drive
trains, radiator mountings, cooling hoses, EVERYTHING - including the
aircraft.

The reliability of the engine itself is not the problem. What brings
the system undone is the vibration induced failure of essential
accessories and other components. Straight, simple engine failures do
occur but a vibration induced failure somewhere else in the chain is
much more likely to leave you in trouble - and it will do so quite
often. Won't extend, won't start, won't retract, broken drive belt, are
all just as much engine failures as a broken crankshaft and much more
common.

I'm afraid that's the dirty, little secret all of us self-launcher
owners keep to ourselves.

Of course except for Schleicher's Wankel. Mind you, when the Wankel
does go you need to have a lot of money saved up. Your local A&P will
be even more reluctant touch it than he is with a 2-stroke so you'll
have to put it in a box and post it to Poppenhausen. That's why Rotax
and Solo still find a home.

Safety - They're all safe if you keep your hand and head out of the prop.

Maintenance - never take your eyes off the wiring, the fuel lines, the
brackets, the flanges, the hose clips, the staked bolts, etc.
Accessible - none of them are accessible within the normal range of
human limb mobility. DON'T buy one that needs to have its fuel lines
changed regularly!

Don't get me started on the engineering quality that demands stainless
braided, aircraft quality fuel lines - joined by NYLON barbed fittings!

And for a normal single-seater, anything less than about 45-50HP is a
sustainer, not a self-launcher, no matter what it says on the box.

GC

On 11/01/2012 11:48, key wrote:
I am curious what group members with experience with self-launchers
regard as the best propulsion system (currently) in terms of in-flight
restart reliability, maintenance, safety, and other operational
factors (e.g., vibration). Of course the electric Antares might win
on all counts except for range, but it is out of my price league.

thanks,

Key

On 1/10/2012 6:41 PM, GC wrote:
A 2-stroke is a 2-stroke is a 2-stroke.

I own one outright, have a share in another,

big snip of vibration related problems


Of course except for Schleicher's Wankel. Mind you, when the Wankel does
go you need to have a lot of money saved up. Your local A&P will be even
more reluctant touch it than he is with a 2-stroke so you'll have to put
it in a box and post it to Poppenhausen. That's why Rotax and Solo still
find a home.

After 17 years, 3300 flight hours, and 170 engine hours, I can report
that vibration related problems with the Wankel (mine and other owners)
are essentially zero. I haven't any engine problems that an A&P couldn't
fix, as none of them involved opening the engine, but only replacing
external components. GC is correct that if it's internal, it goes back
to Schleicher, as no one in the USA works on the innards.

Don't get me started on the engineering quality that demands stainless
braided, aircraft quality fuel lines - joined by NYLON barbed fittings!

The ASH 26 E came with metal fittings from the very start in 1994, and
it's replacement, the ASH 31 Mi, continues that tradition. Another
feature is the engine does not move with the prop, as the prop is on a
mast that pivots while the engine remains bolted to the fuselage (rubber
mounts, of course). This eliminates electric cable and fuel line
flexing, and mating problems with the exhaust system, although the
radiator hoses must flex (that's not bee a problem).

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

As Eric's post suggests, Schleicher's Wankel engine provides a very
good solution for self-launching. Probably the best available if one
considers lack of vibration, power density, and range. If range isn't
so important, then electrics are promising- - assuming the batteries
behave themselves.

Like Eric, I have a Wankel also, but with less than 40 hours.
Reliability has been excellent. The engine, with its small form
factor, allows the fuselage boom to be slim as compared to most 2-
strokes.

The Wankel is a bit less fuel effecient than a piston engine. It makes
more waste heat too, and this means a longer cool down period is
required. Depending on OAT, I use as much as 3 to 5 minutes. However,
retracting the pylon most of the way, until the prop tip just drops
out of sight in the little rear view mirror, results in minimal drag
penalty when slowed up to work even weak lift during cool down. The
sound of the engine bay doors snapping shut is music to the ear, as it
signals the motor is tucked away and your a glider!

When Eric allowed as to how the motor would be shipped back for
anything internal, I would emphasize that most anything* that might go
wrong or require maintenance is external to the rotor and engine case
itself. Most all the accessory stuff is servicable here in the US.
There are some excellent mechanics who know the Wankel well, like Rex
Mayes at Williams, CA, and others I'm sure - - so it's not at all like
owning an orphan.

I appreciate things mechanical and am happy with my 26E. That said,
the Antares pylon extend and retract sequencing is just cool to watch,
and the ship's engineering is impressive.

*Exceptions I'm aware of have involved either starving the engine of
oil or not properly storing the engine for extended periods of non
use. Both situations are easy enough to avoid, and very expensive if
ignored.

bumper
MKIV & QV
Minden

Hello Key,

While you are stirring the pot, I may as well join in.

The best self launching glider or the best self launcher propulsions
system? They're not necessarily the same thing. Some gliders are
fairly well sorted as self launchers and may not be the best glider
but may be the best self launching glider. Some propulsion systems may
be brilliant as an idea but not completely suited to the application…
at least not with the current state of the art.

And what sort of flying do you want to do? Self launch and the
occasional single or double motor run retrieve or is the main purpose
of the glider things like long distance safaris where longer range is
required and where jet fuel or battery charging facilities may not be
available at the remote airfield?

Does the region you fly in have big sink? My SLG does 800 fpm or
better climbing under motor and I have seen zero on the dial for a
minute or two when doing an in-air restart. Bear that in mind when
considering the possible height gain on an electric powered glider.
You may lose 50% of your motor run before you actually gain any
height.

How long will you keep the glider and how much money do you expect to
lose when reselling the glider? 2 stroke self launchers have held
their price remarkably well but I doubt that you'd get the same thing
with electric powered gliders, close to a battery replacement time.
Gliders like the PIK 20E and the DG-400 are 25 and more years old and
still going strong. I sold my DG-400 unseen within 3 days of
advertising it and had enquiries from Patagonia to Austria. The buyer
said, 3 months later, that the glider was "everything he dreamed it
would be".

I've seen one jet self-launcher take off and it was frankly
terrifying… both in terms of the noise and the lack of height gained.
And the massive fuel use.

Water cooled two strokes have been around for 80 years or more and the
technology is very well understood. Yes, vibration is a bit of a
problem but it's hardly a disaster. Jet and electric power plants have
not been around very long and the technology is changing every year…
or faster. Yes, the batteries may last 1000 cycles (I have NEVER known
any battery actually do that or even vaguely meet the manufacturer's
promised lifetime) but are the manufacturers of the glider going to re-
certify items like new battery technology, new speed controllers and
new electric motors every few years to replace the obsolete versions?
They don't have a great history in doing that with other items!

Regrettably, in my opinion right now, if you are not a millionaire and
you want to fly some distance away from your home strip, the best
choice is petrol or petrol.

The ASH owners are fairly vocal on this list but you don't hear much
from DG owners, so here's a bit. I have owned 2 DG gliders and believe
that they are the best sorted SLG out there. I think DG take self
launching gliders very seriously and it shows in almost everything
from the brilliant DEI-NT to the steering tailwheel, large wingtip
wheels, taxiing wingtip dolly etc. etc. as well as progressive safety
features like the Piggott hook and NOAH.

Certainly, in terms of serious problems, the DGs in our region do
very well compared with others which have a reputation for self
combusting is significant numbers!

I agree with GC in that you cannot have too much power and under
powered SLGs are terrifying, both inside and outside the cockpit. The
climb rate on take off in my glider is very impressive… I have never
watched but whenever I land, people come over and talk about it. Only
last week, two other pilots, one of whom has an Arcus on order, stated
that in his opinion, "DG make the best SLGs… period". The other wanted
to buy a share in the glider. The DG 808 is the glider of choice in
places like the Alps where climb rate and reliable engine starting
really counts.

Look at the sales figures for SLGs over the last 25 years. One
manufacturer has sold over 50% more single-seaters than the others… it
might be close to double the amount of the nearest competitor.

Like Bumper, I appreciate things mechanical… it's my job… and I have
to say that I don't see any of the current IC SLGs being perfect and
in many ways you pays your money and you takes your choice of the type
of problems you want to run into… vibration, fire, breaking belts due
to backfiring, breaking belts due to bending incorrectly when stowing
the engine… there's quite a laundry list. However, the benefits appear
to largely outweigh the drawbacks. And I bought two DGs.

You can find a fairly full run down of the options he

http://www.keepitsoaring.com/LKSC/Do...ember_2010.pdf

D

My vote is FES. 2 seconds from gliding to power, imperceptible drag.

Mine is a self sustainer, not SL, but a SL is under development and
has flown successfully.

When widely available, I think it is a strong contender.

At present it would not be all things to all people – e.g. not coping
well with 800 fpm sink, and more limited range than petrol models. But
all glider choices are compromises – you have to pick what most
closely suits your priorities. FES suits mine.

Chris N.

On Tuesday, January 10, 2012 9:09:57 PM UTC-5, T wrote:
Please explain.

Sure, many reasons:

BACKGROUND: All your planning flying any pylon-powered
toy must be around worst case: engine stuck out and not
running. Depending on the model, this can mean very
high sink rates, and badly degraded handling from
wake of pylon and radiator on tail.

The "motor out and not running" MOANR configuration
must be used to plan safety of take-off strip,
departure pattern, distance from airport, air-start
altitude and placement margins, etc.

Antares low-shutdown advantages:
- low sink rate and normal handling with MOANR
- only one control in cockpit to extend/retract
(unlike some which have VERY high workloads)
- normal handling under power makes it easy to
find and center first thermal
- no required cool-down cycle prior retraction
- ~10 second re-extension to power if I don't
climb after shutdown

All the above mean I can concentrate on finding
and centering the first thermal rather than
"engine management", with low stress. My average
shutdown is ~1000 feet, in locations where there
is lift near the launch and not too much traffic
(ie, Sterling, Hobbs, Uvalde). This leaves a very
substantial reserve for self-retrieve, though
this is certainly not a power XC cruiser.

Hope that helps !
Best Regards, Dave "YO electric"

PS: Someone needs to come up with a really good
and appropriately foul acronym for "motor out and
not running".
Boggs, you're on...

On Wednesday, January 11, 2012 8:11:29 AM UTC-5, Chris Nicholas wrote:
My vote is FES. ...imperceptible drag.

Has anyone MEASURED the drag, especially at high speed ?