Small turbines for homebuilts?

[David Findlay]

Has there been any development of small jet engines for light aircraft, like
the engines used on the Eclipse 500? Small turbines would be great for high
performance homebuilts if they were cheap enough. Anything down to the
price level that could compete with high horsepower Lycoming's or
Continentals? Thanks,

David

[ventus2]

David,

Not competing with high horsepower output like your top Lycombings or
Conti;s but interesting nevertheless.
Check out http://www.tjt.bz/ as these engines are being used very
successfully in gliders at the moment. No idea on performance figures, fuel
burn etc.

Chris

[Bill Daniels]

"ventus2" > wrote in message
...
> David,
>
> Not competing with high horsepower output like your top Lycombings or
> Conti;s but interesting nevertheless.
> Check out http://www.tjt.bz/ as these engines are being used very
> successfully in gliders at the moment. No idea on performance figures,
fuel
> burn etc.
>
> Chris
>

These little centrifugal turbojets are very inefficient consuming about
10GPH of Jet A for 50 pounds of thrust. Still, they are very cool.
Efficiencies are getting better so there's hope. I keep hearing rumors of a
8" diameter turbofan that would halve the fuel consumption.

Even today, they are a very interesting when applied to gliders. 50 pounds
of thrust would push my glider along at about 120 knots - probably a lot
more at high altitudes. Since it already has 75 gallon tanks in the wings
normally used for water ballast that could easily be converted to fuel
tanks, the range would be impressive. The airframes' aerodynamic efficiency
offsets the inefficient engine.

The engines tiny size and weight makes it easy to retract the engine into
the fuselage when flying as a glider.

Bill Daniels

[John]

Bill Daniels wrote:

>
> "ventus2" > wrote in message
> ...
>> David,
>>
>> Not competing with high horsepower output like your top Lycombings or
>> Conti;s but interesting nevertheless.
>> Check out http://www.tjt.bz/ as these engines are being used very
>> successfully in gliders at the moment. No idea on performance figures,
> fuel
>> burn etc.
>>
>> Chris
>>
>
> These little centrifugal turbojets are very inefficient consuming about
> 10GPH of Jet A for 50 pounds of thrust. Still, they are very cool.


There 30lb thrust model specs at 5.5 gal/hour (350ml/min) which isn't
horrible for a jet. At speed 30lb is roughly 30hp so it takes 3.3 times to
get 100hp so 18 gal/hour which is about 3 times more fuel than a ricip but
it sure could be a lot of fun ;-)
John

[Bill Daniels]

"John" > wrote in message
...
> Bill Daniels wrote:
>
> >
> > "ventus2" > wrote in message
> > ...
> >> David,
> >>
> >> Not competing with high horsepower output like your top Lycombings or
> >> Conti;s but interesting nevertheless.
> >> Check out http://www.tjt.bz/ as these engines are being used very
> >> successfully in gliders at the moment. No idea on performance figures,
> > fuel
> >> burn etc.
> >>
> >> Chris
> >>
> >
> > These little centrifugal turbojets are very inefficient consuming about
> > 10GPH of Jet A for 50 pounds of thrust. Still, they are very cool.
>
>
> There 30lb thrust model specs at 5.5 gal/hour (350ml/min) which isn't
> horrible for a jet. At speed 30lb is roughly 30hp so it takes 3.3 times to
> get 100hp so 18 gal/hour which is about 3 times more fuel than a ricip but
> it sure could be a lot of fun ;-)
> John

If I recall correctly, one pound of thrust = one HP at around 325 knots.
That's quite a bit of 'at speed'.

[[email protected]]

The most dependable, at the moment, are these

http://www.amtjets.com/

The top model gives 51,7 pounds of thrust.
I've seen many of them "At work" on RC models. Amazing.

Piero

[John]

Bill Daniels wrote:

>> There 30lb thrust model specs at 5.5 gal/hour (350ml/min) which isn't
>> horrible for a jet. At speed 30lb is roughly 30hp so it takes 3.3 times
>> to get 100hp so 18 gal/hour which is about 3 times more fuel than a ricip
>> but it sure could be a lot of fun ;-)
>> John
>
> If I recall correctly, one pound of thrust = one HP at around 325 knots.
> That's quite a bit of 'at speed'.

That sounds about right, I didn't have the figures in front of me. Even so
if you slowed it down to 150-200 you'd still have a fairly potent engine
for the weight. And it still would be a blast!
John

[John]

wrote:

> The most dependable, at the moment, are these
>
> http://www.amtjets.com/
>
> The top model gives 51,7 pounds of thrust.
> I've seen many of them "At work" on RC models. Amazing.
>
> Piero

They spec 10.5 gal/hour for 52 lb thrust (51.7 actually). Which is close to
what the other 30 /b unit spec'ed
John

[pittss1c]

wrote:
> The most dependable, at the moment, are these
>
> http://www.amtjets.com/
>
> The top model gives 51,7 pounds of thrust.
> I've seen many of them "At work" on RC models. Amazing.
>
> Piero
>
Did you see the skydiver with a wingsuit with 2 jets strapped to his boots?


http://www.bird-man.com/?n=windtunnel&nose=6

[Morgans]

"pittss1c" > wrote

> Did you see the skydiver with a wingsuit with 2 jets strapped to his
boots?
> http://www.bird-man.com/?n=windtunnel&nose=6

Too cool !!!

Did you hear him say that he was able to maintain level flight for half a
minute, until his tanks went dry? That is what I think he said.

Lets see, what if you put 6 or 8 of those 50 pound thrust units in a jetpack
type of arrangement. You should be able to maintain level hovering flight,
right? Fuel demands would mean that you could not hover for very long, but
it would be much longer than the current jet packs in use, right?

You know, if I had enough money, I might just take that project on!
--
Jim in NC

[Rich S.]

"Morgans" > wrote in message
...
>
> Lets see, what if you put 6 or 8 of those 50 pound thrust units in a
> jetpack
> type of arrangement. You should be able to maintain level hovering flight,
> right? Fuel demands would mean that you could not hover for very long,
> but
> it would be much longer than the current jet packs in use, right?
>
> You know, if I had enough money, I might just take that project on!

Damn, Jim. I'd spend a buck to watch!

Rich S.

[Jim Carriere]

John wrote:
> Bill Daniels wrote:
>
>>> There 30lb thrust model specs at 5.5 gal/hour (350ml/min) which isn't
>>> horrible for a jet. At speed 30lb is roughly 30hp so it takes 3.3 times
>>> to get 100hp so 18 gal/hour which is about 3 times more fuel than a ricip
>>> but it sure could be a lot of fun ;-)
>>> John
>> If I recall correctly, one pound of thrust = one HP at around 325 knots.
>> That's quite a bit of 'at speed'.
>
> That sounds about right, I didn't have the figures in front of me. Even so
> if you slowed it down to 150-200 you'd still have a fairly potent engine
> for the weight. And it still would be a blast!

Yep, 375mph (or 325 knots). If you factor in propeller efficiency, it's
lower. The math is pretty simple if you know the prop efficiency
(usually about 80% or so), you multiply the two, so in reality the magic
number is about 300mph or between about 250-275 knots.

In other words, a 100hp engine makes 200 pounds of thrust at about
150mph, 100 lbf at 300mph, 50 lbf at 600mph (and so on, putting it
simply). Or, a 30 lb thrust engine is equivalent to a 15hp prop job at
150mph, 30hp at 300mph...

Quite a bit of "at speed."

Static thrust comparisons are a little more complicated, that depends a
lot on the propeller.

[Bill Daniels]

"Rich S." > wrote in message
. ..
> "Morgans" > wrote in message
> ...
> >
> > Lets see, what if you put 6 or 8 of those 50 pound thrust units in a
> > jetpack
> > type of arrangement. You should be able to maintain level hovering
flight,
> > right? Fuel demands would mean that you could not hover for very long,
> > but
> > it would be much longer than the current jet packs in use, right?
> >
> > You know, if I had enough money, I might just take that project on!
>
> Damn, Jim. I'd spend a buck to watch!
>
> Rich S.
>
You guy thinking of trying for a 'Darwin Award'?

[clipclip]

Has there been any development of small jet engines for light aircraft, like
the engines used on the Eclipse 500? Small turbines would be great for high
performance homebuilts if they were cheap enough. Anything down to the
price level that could compete with high horsepower Lycoming's or
Continentals? Thanks,

David

there are "scratch designed & built" 150 hp-equivalent turboprop engines on the market - check out www.innodyn.com - they flew to oshkosh with a turbine equipped super cub ( http://www.innodyn.com/aviation/news_archives/news_08_05_05_01.html ). furthermore, they claim to burn only slightly more than a piston engine, which i find remarkable. they say they have a twinpac planned which would output 300 hp.

francois

[Pete Schaefer]

You mean something like this?
http://innodyn.com/aviation/index_aviation.html

"David Findlay" > wrote in message
...
> Has there been any development of small jet engines for light aircraft,
like
> the engines used on the Eclipse 500? Small turbines would be great for
high
> performance homebuilts if they were cheap enough. Anything down to the
> price level that could compete with high horsepower Lycoming's or
> Continentals? Thanks,
>
> David

[Flyingmonk]

I'll put in in a buck... LOL

[Morgans]

"Flyingmonk" > wrote in message
oups.com...
> I'll put in in a buck... LOL
>
LOL!!! OK, that's part of the money.

Let's see - those engines are around 3700 bucks per copy. With 8 engines,
that would be 29,600 bucks. I'll throw in the plumbing and harness, ect.,
myself.

Two donations so far. I only have to hear from 29,598 more people that are
putting a buck in! Less, if someone throws 2 bucks (or more) in! <VBFG>
--
Jim in NC

[[email protected]]

> They spec 10.5 gal/hour for...

Correct.
The good thing about AMT is the MTBF, which is considerably longer.

This, mounted on a real aircraft instead of a RC model, can be quite
reassuring.

Piero

[John]

Morgans wrote:

>
> "Flyingmonk" > wrote in message
> oups.com...
>> I'll put in in a buck... LOL
>>
> LOL!!! OK, that's part of the money.
>
> Let's see - those engines are around 3700 bucks per copy. With 8 engines,
> that would be 29,600 bucks. I'll throw in the plumbing and harness, ect.,
> myself.
>
> Two donations so far. I only have to hear from 29,598 more people that
> are
> putting a buck in! Less, if someone throws 2 bucks (or more) in! <VBFG>


I can go $2.00 bucks! ;-)
John

[Lars]

This ha actually been done here in Sweden. Two "model size" turbojets
atop the fuselage of a two-seat glider. Not enoug thrust for take-off
but plenty of power to fly home in marginal conditions to avoid an
"out" landing. I beleive they quoted 1-2 m/s climb rate.

[[email protected]]

> ...Not enough thrust for take-off ...

If your plane is small enough...

http://flight.cz/cricri/photos/unsorted/cri_cri_10_gallery.jpg

Piero

[Dan, U.S. Air Force, retired]

Bill Daniels wrote:
> "Rich S." > wrote in message
> . ..
>
>>"Morgans" > wrote in message
...
>>
>>>Lets see, what if you put 6 or 8 of those 50 pound thrust units in a
>>>jetpack
>>>type of arrangement. You should be able to maintain level hovering
>
> flight,
>
>>>right? Fuel demands would mean that you could not hover for very long,
>>>but
>>>it would be much longer than the current jet packs in use, right?
>>>
>>>You know, if I had enough money, I might just take that project on!
>>
>>Damn, Jim. I'd spend a buck to watch!
>>
>>Rich S.
>>
>
> You guy thinking of trying for a 'Darwin Award'?
>

Hey, live in fame, go down in flames :)

Dan, U.S. Air Force, retired

[Morgans]

> If your plane is small enough...
>
> http://flight.cz/cricri/photos/unsorted/cri_cri_10_gallery.jpg

I believe that plane lifted off from the roof of a speeding car, so really,
not enough to take off. Perhaps if you had a very very long runway? <g>
--
Jim in NC

[Kyle Boatright]

"clipclip" > wrote in message
...
>
> David Findlay Wrote:
>> Has there been any development of small jet engines for light aircraft,
>> like
>> the engines used on the Eclipse 500? Small turbines would be great for
>> high
>> performance homebuilts if they were cheap enough. Anything down to the
>> price level that could compete with high horsepower Lycoming's or
>> Continentals? Thanks,
>>
>> David
>
> there are "scratch designed & built" 150 hp-equivalent turboprop
> engines on the market - check out www.innodyn.com - they flew to
> oshkosh with a turbine equipped super cub (
> http://www.innodyn.com/aviation/news_archives/news_08_05_05_01.html ).
> furthermore, they claim to burn only slightly more than a piston
> engine, which i find remarkable. they say they have a twinpac planned
> which would output 300 hp.
>
> francois
>
>
> --
> clipclip

If you read more carefully, Innodyne is taking existing turbines and adding
their fuel control system. Also, given the consensus that a turbine simply
can't offer the specific fuel consumption (or even close) to a recip, their
data on fuel consumption (or rather, the lack of hard data) seems suspicious
to me.

Innodyne has been in this game for years and to the best of my knowledge
have never delivered a single customer engine. I'd stay away until they
have a track record and can provide substantial independant confirmation of
their fuel consumption claims.

KB