Pulsejet-powered sailplane

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Bruno Ogorelec
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Pulsejet-powered sailplane

Post by Bruno Ogorelec » Sun Dec 14, 2008 9:30 pm

http://www.lange-flugzeugbau.com/htm/en ... s_18p.html

Some dubious claims here. The engine is said to represent "the leading edge of a family of jet engines, which can be traced back through more than 60 years of German aviation technology". Haw-haw-haw...

Interesting, that they are using the FWE tag for the engine... I thought it was Larry's property.

hinote
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Re: Pulsejet-powered sailplane

Post by hinote » Sun Dec 14, 2008 11:25 pm

Bruno Ogorelec wrote:http://www.lange-flugzeugbau.com/htm/en ... s_18p.html

Some dubious claims here. The engine is said to represent "the leading edge of a family of jet engines, which can be traced back through more than 60 years of German aviation technology". Haw-haw-haw...

Interesting, that they are using the FWE tag for the engine... I thought it was Larry's property.
That's an interesting find--Thanks, Bruno!

It should be noted that the word "sustainer" is used to describe the engine function. This means in standard sailplane parlance it can keep the aircraft airborne but will not have enough power for takeoff, and has very little ability to power the A/C into a climb.

At an assumed glide ratio of 50:1 and a gross weight in the 800-850 lb range (typical for a modern 18-meter sailplane), the thrust required would be on the order of 16-17 lbf--hardly spectacular, and more of a testament to the airframe's performance than the engine.
Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

hinote
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Re: Pulsejet-powered sailplane

Post by hinote » Mon Dec 15, 2008 1:07 am

hinote wrote: At an assumed glide ratio of 50:1 and a gross weight in the 800-850 lb range (typical for a modern 18-meter sailplane), the thrust required would be on the order of 16-17 lbf--hardly spectacular, and more of a testament to the airframe's performance than the engine.
BTW just so yous guys can get a handle on how efficient a modern sailplane is:

The max L/D ratio is achieved when the induced drag (that's the drag created due to lift) equals the sum of all other drag contributors. So, the residual drag of the aircraft is actually only 8-8.5 lb. (this takes the form of skin-friction and form drag for the majority, and to use commonly quoted terms). Each of these involves changing the velocity and/or the direction of the local airmass.

For perspective, that means the wing (with a span of almost 60 feet) has the same drag as a piece of 1/8-inch diameter wire of the same span--and the fuselage has a total drag number of something like 6 lbf. It's not hard to see how these amazing machines can achieve cross-country speeds well in excess of 100 mph average in good soaring conditions.

I have personally experienced cross-country speeds of 135 mph and more over distances in excess of 100 miles, with sailplane technologies developed in the 1970's.
Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

larry cottrill
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Re: Pulsejet-powered sailplane

Post by larry cottrill » Mon Dec 15, 2008 2:10 pm

Bruno Ogorelec wrote:http://www.lange-flugzeugbau.com/htm/en ... s_18p.html

Some dubious claims here. The engine is said to represent "the leading edge of a family of jet engines, which can be traced back through more than 60 years of German aviation technology". Haw-haw-haw...

Interesting, that they are using the FWE tag for the engine... I thought it was Larry's property.
I consider 'FWE' to be a sort of generic description. Anyway, I'm not exactly fiscally equipped to fight for "rights" to names. If they tried to use one of my "Lady" names, I would complain loudly, but they would probably just yawn.

If this works, the FWE will finally be "mainstream" - ha. I can put something on my tombstone, like the guy who wrote The Woman In White -- "I Designed the Short Lady, FWE". There could be a little silhouette of her just above the inscription. Ha.

It does look a little dwarfish on that fuselage, but as Bill Hinote points out, on a sailplane it wouldn't take much to do what they want. I only wish they'd chosen a later FWE version; they could have gotten by with an even smaller one, or used one about that size and had some real performance.

L Cottrill

milisavljevic
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Re: Pulsejet-powered sailplane

Post by milisavljevic » Mon Dec 15, 2008 2:24 pm

.
Great catch, Pater Bruno!

The pulsejet shown appears to be an exact 3:1 scale up of Eric Beck's "Advanced FWE", save for the fact
the intake duct appears to be nearer ID 70 mm than ID 63 mm (what a 3:1 scale up implies). I would like
to know if Mr. Beck was involved, or if these chaps felt free to appropriate Larry's pretentious name and
Eric's improvement to what is otherwise a limited design? Low thrust density and high SFC combine here
to severely dilute the desired goal of a simple, lightweight, and (relatively) efficient sustainer jet engine.

I know that if Eric was involved that he could have provided a much better design from his own research.

Someone should point out that the pulsejet was NOT a German invention, and perhaps throw them a link
to the Snecma Emouchet. Not that they would appreciate either. Their aircraft are first rate, and I know
the works of some of their technical staffs, and the future collaboration with DLR sounds very promising.

Bit of mystery then, this combination of state-of-the-art sailplane and poor pulsejet. Eric, are you there?

Cheers,
M.

Edit: I agree with you, Larry; if in the "FWE market", a later version would have made the better choice.
Last edited by milisavljevic on Tue Dec 16, 2008 2:43 am, edited 2 times in total.
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larry cottrill
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Re: Pulsejet-powered sailplane

Post by larry cottrill » Tue Dec 16, 2008 4:17 pm

How about that "30 HP"? That would be, roughly speaking, 20 TIMES the power of the standard Advanced FWE. Seems like a lot of improvement for a 3x scale-up. Note that in their nice cutaway view, they show fueling right at the intake flare, usually an inefficiency. Of course, that may have changed with development; you can't tell anything from the photo as to how deep the fuel pipe runs. As it stands, that would be an awfully long path for mixing flow, but of course that would be all right if the delivery pressure (and hence, ejection speed) were high enough. Looks like they're using a nicely manufactured nozzle there, probably suited for fairly high static pressure. Maybe that would improve efficiency in some way, too, due to entrainment or something.

It's awful when the world just goes on without you, casting you aside like an old shoe. Sniff ;-)

L Cottrill

Viv
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Re: Pulsejet-powered sailplane

Post by Viv » Tue Dec 16, 2008 5:05 pm

Hi Larry

I think that fueling arrangement is just an untried picture of what some one thought was a good idea ;-) they certainly were waxing lyrical over the range of suitable fuels that would work with it, bunker fuel? that must have been a joke as it would clog the heat exchanger coil with coke very quickly, as would vegetable oil for the same reasons, you cant just run low quality contaminated fuels though a heat exchanger and not expect oxidization and coking.

On the other hand the electric drive motor is very nice, this is similar to a variable frequency generator I have been working on and off for the last few years, the mechanical arrangement I like a lot.

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

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Monsieur le commentaire

larry cottrill
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Re: Pulsejet-powered sailplane

Post by larry cottrill » Tue Dec 16, 2008 6:12 pm

Viv -

It's interesting because of their test run photo (completely unretouched, I'm sure ;-), showing the intake flame no more prominent than the tail flame. That suggests to me an awfully efficient mode of operation for this intake style. Obviously, there's no indication of whether this is a vapor or liquid fuel run, or whether it's a run at or near full power, etc. But, you certainly don't see an FWE running that way very often.

Then again, appearances can be deceiving. It's just interesting to think that they've really got it "balanced out" that way. The photo might mean little or nothing in terms of reality, I suppose.

L Cottrill

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Re: Pulsejet-powered sailplane

Post by Irvine.J » Wed Dec 17, 2008 12:03 am

I'm inviting this man to the forum for discussions on this project to address comments and concerns in a public forum :D
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Irvine.J
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Re: Pulsejet-powered sailplane

Post by Irvine.J » Wed Dec 17, 2008 12:19 am

I have sent this, so we'll see what happens.

Dear Sir/Madam,
I would like to formally invite you or your research staff involved in the pulsejet propulsion system in your Antaries 18P project
to join us on the forum for discussion, and to address any questions they may have on the subject.
The link to the website forum is http://www.pulse-jets.com

The direct link to the discussion is here, and it is very easy to register. viewtopic.php?f=13&t=5111&p=60228#p60228

We hope that your technical staff involved in the pulsejet development can join in our discussion and shed some light on a few things.
Regards,
James Irvine

IRVINE AEROPULSE
James- Image KEEPING IT REAL SINCE 1982
http://pulseairdefence.com
[url=callto://project42labs]Image[/url]

Jutte
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Re: Pulsejet-powered sailplane

Post by Jutte » Tue Dec 23, 2008 12:36 am

Yeah - I saw that sail plane site quite awhile ago and thought...
"Ohh look ...these guys are using a big FWE...just like the guys here are!"
It kind of looks like they're been a-googling doesn't it !
I got the impression that they had just started out on the whole thing.
Although... I would say the sail plane communtity isn't ready for the sound
of a FWE that big.Heck - when I was flying sail planes in Australia guys with
the pop up engines were sometimes given the hairy eye ball ( due to the noise and mostly envy).
The modern sail planes are super slick and slippery - once with an instructor
we did a tail wind landing( his idea not mine).It was pretty mundane landing until we used up the WHOLE
runway and had to go into the car park!
Lucky it was a BIG car park - still it was really exciting sitting in the front of a
really expensive aircraft - trying to think small thoughts - while the instructor tap danced
on the rudders trying to dodge BMW's and Toyota Land Cruisers.
Still I can say I've been in a sail plane that was parked in a car park....LOL!

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