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NASA sponsored GAP Engine

Freemasm

Well Known Member
Previous thread triggered some ancient memories. Does anyone remember the NASA GAP program? Continental won the development bid with a (2 stroke?) design. The specs called for Jet A fueled engine to be rated at 200HP at only 2400 RPM. The spec was also very aggressive in other areas such as repair/OH intervals, parts count, etc. This is all from memory so forgive any errors. There was also a turbine engine spec that I believe Williams International won.

Per the Continental engineer I spoke with at SnF a million years ago, if any OEM picked up the engine for their new product line then the engine would go into production. I doubt that was completely true since it has been relegated to the round file with many others.

Does anyone have any details? HP/Torque//RPM curves. actual performance numbers? History? The ultimate fatal flaw?

Anything would be appreciated. It looked so promising way back when.
 
Trying to restore some visibility. Anyone have anything to add? When I talked to the Continental reps a month or so ago, the consistent response was "that was before my time." Someone has to know something. Any history or details that anyone could be share here would be appreciated.
 
Trying to restore some visibility. Anyone have anything to add? When I talked to the Continental reps a month or so ago, the consistent response was "that was before my time." Someone has to know something. Any history or details that anyone could be share here would be appreciated.

It was a two-stroke diesel (Detroit Dieselish), with 4 valves, roots blower, and turbocharged. Fork and blade rods so the cylinders were in line. Individual pumps so they could be replaced. My very good friend (and best design engineer I ever met) Bill Brogdon was the chief designer. Bill and I spent many after hours at the chalk board diagramming and discussing the key aspects of component testing and validation that make diesels stay in one piece with high cylinder pressures. He knew well the issues and how they differed from gasoline design/development process. Ricardo was a sub contractor for thee combustion chamber design and analysis. I do recall some discussion about the challenges of the piston ports, ring flutter and bore distortion. A modern common rail would have been much lighter, and could have used rate shaping to handle the wide range of issues for installation in a light airframe. BMEP was not too high, and since 2-stroke, the idle speed compression and firing impulse was manageable. Individual pumps was a clunky design. At this time the rules of thumb for new engine development costs were $150M for each - design/analysis - development - production tooling. This is orders of magnitude above the industries abilities to cover and recover. All said, todays economies of analysis tools, available fuel systems, and emissions emphasis would might present a good good opportunity to have a redo. A small line item in a $2 trillion bill. :eek:

The reason for roots blower was starting and gettin the air flowing. It was the easy choice compared to other fancy means of ensuring low smoke on starting.

Why failed? My understanding is that a new President came in and knew everything.:rolleyes: Lots of command decisions for all things technical and the best people (last standing) left including Bill. The engine got heavier, and NASA was unhappy and the contract died. Continental was a money maker for Teledyne and had to send money home each week, struggled for R&D money and lived on government contracts like this to retain the best technical people, and they were really good. Just nature of that business.

Sorry, maybe NASA has some reports posted on the targets for SFC etc. The design team knew well what it had to do to be competitive.
 
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Thanks BillL

IIRC:

SFC was 0.75
TBO was 1.50
Others for sound power level.
Parts count (cost)
etc.

Benchmark for most design parameters was the Lyc IO360.

You'd think someone would try and buy the IP if there was/is real value there.
 
Since those were our tax dollars funding the design, how about open-sourcing all the documents and test data? Metal 3D printing is a thing nowadays, it would not be so difficult or expensive to build an experimental version of this engine if one didn't have to rediscover the wheel every time and recoup the cost of experimentation.
 
There was a turbine engine as well as a recip engine developed as part of the GAP program. I was an engineer at Williams International back in those days. We manufactured several components of the FJX-2 turbine engine at my site. The design goal was to make an engine weighing 85 lbs and producing 800 lbs thrust.
An early version of the Eclipse Jet was fitted with 2 FJX engines. The plane made 2 marginally successful flights before the program was cancelled.
 
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You'd think someone would try and buy the IP if there was/is real value there.

I would think the Honda/Continental engine might be of more interest. In dreamland I ponder an open funded, developed, and component sourced design within the experimental community. Like the CAD sharing community. Imagining different compartments for CFD, Dynamics, FEA/stress analysis, manufacturing planning, and CNC machining of components. Yes castings too. The cannibalistic competitive patent trolls would be poison.

Since those were our tax dollars funding the design, how about open-sourcing all the documents and test data? Metal 3D printing is a thing nowadays, it would not be so difficult or expensive to build an experimental version of this engine if one didn't have to rediscover the wheel every time and recoup the cost of experimentation.

FOIA Request ?
 
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Since those were our tax dollars funding the design, how about open-sourcing all the documents and test data? Metal 3D printing is a thing nowadays, it would not be so difficult or expensive to build an experimental version of this engine if one didn't have to rediscover the wheel every time and recoup the cost of experimentation.

Google “NASA GAP engine program results” and you’ll find lots of links that will lead you to lots of links, which will lead you to....... Yes, it was your tax dollars, and yes - the results are available.
 
Thanks !!

Google “NASA GAP engine program results” and you’ll find lots of links that will lead you to lots of links, which will lead you to....... Yes, it was your tax dollars, and yes - the results are available.

I have not found any actual reports via google and links, but - - the NASA report server hit paydirt immediately. Several volumes of reports on the diesels but nothing on the GAP publicly promoted.
Update:the General Aviation Propulsion program reports for the Williams work is published, but not Teledyne. I will call NASA Glenn tomorrow . . . more to come.
 
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No joy . . . . .

Google “NASA GAP engine program results” and you’ll find lots of links that will lead you to lots of links, which will lead you to....... Yes, it was your tax dollars, and yes - the results are available.

Well, I am now ready to say "the results are not available", at least not publicly. After searching The NASA Technical Report Server extensively and Google of course, nothing of a report was found. The Williams turbine portion of the GAP had a very well documented and written report, but nothing on the Teledyne Continental Mobile engine.

I contacted ( a story in itself) the Nasa Glen person listed on one press release. He actually called me and then followed up with a few documents. All were internal letters with the same announcements found in multicolor on Google. No new information.

I know for a fact that the project was initially funded and a design was created for the engine. Ricardo (Shoreham by the sea) was contracted (WAVE) to do the gas dynamics and combustion simulation for the engine to product performance. New company management resulted in many changes internally and this project seemed for fall out of focus. That is where knowledge of my contact ended. Now, since there was money paid, there will be reports to NASA of all the activities and conclusions with fundamental information. Since the government never forgets, it is somewhere, but I could not find it and the NASA guy did not find it either.

Edit: The Deputy Communications Director did talk to a person associated with the Glen side and they said "it stopped when NASA refused to let them fly the aircraft". I interpret that as a failure to meet program goals, or some other contract issue and funding was stopped at that point. It sounds very unhappy. Maybe they only publish final reports and not progress reports?

So, if it is another avenue to pursue for obtaining reports, please let me know.
 
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I have this .pdf from someone I hope I don't get into any trouble over posting this. I checked the links in the footer of each page but they're long gone. At least they were in the public domain at one point...

There is also a very early TCM diesel radial engine from the 80s, I think. All interesting stuff but ultimately demonstrating how hard it is to do some of this stuff, even with major sponsorship.
 

Attachments

  • TCM-NASA-GAP Engine.pdf
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On a two-stroke engine the connecting rod is (more-or-less) always in compression so you don't need the bottom half of the big end of the conrod. In practice you need the retaining collar to keep things together during starting and abnormal events like high piston friction from a partial siezure.
 
On a two-stroke engine the connecting rod is (more-or-less) always in compression so you don't need the bottom half of the big end of the conrod. In practice you need the retaining collar to keep things together during starting and abnormal events like high piston friction from a partial siezure.

This is the first (only) photos I have seen of this interior. I thought the rods were fork and blade, but alas, not so. Also note there is no (little) provision for compression retention of the piston to rod connection. It really seems like an overly complex design for low cost, fault tolerance and reliability.

It is hard to tell, but did that crank look like it had failed rod bearings?

It certainly looks like the design/analysis budget was milked well.

I am seriously disappointed that the NASA Glen communications office failed to locate this presentation.

Thanks for posting this.
 
Previous thread triggered some ancient memories. Does anyone remember the NASA GAP program? Continental won the development bid with a (2 stroke?) design. The specs called for Jet A fueled engine to be rated at 200HP at only 2400 RPM. The spec was also very aggressive in other areas such as repair/OH intervals, parts count, etc. This is all from memory so forgive any errors. There was also a turbine engine spec that I believe Williams International won.

Per the Continental engineer I spoke with at SnF a million years ago, if any OEM picked up the engine for their new product line then the engine would go into production. I doubt that was completely true since it has been relegated to the round file with many others.

Does anyone have any details? HP/Torque//RPM curves. actual performance numbers? History? The ultimate fatal flaw?

Anything would be appreciated. It looked so promising way back when.

My guess is that NASA, as well as others looking into alternative GA propulsion, have abandoned all fossil fuel engine development in favor of electric.
 
My guess is that NASA, as well as others looking into alternative GA propulsion, have abandoned all fossil fuel engine development in favor of electric.
As much as I love IC engines, this is probably a wise decision. Investing in battery technology is probably the best use of money today. There will be a huge breakthrough in the coming years - there are many smart people working on it. We got to the moon in 10 years, and invented many of the things needed along the way.
 
This is the first (only) photos I have seen of this interior. I thought the rods were fork and blade, but alas, not so. Also note there is no (little) provision for compression retention of the piston to rod connection. It really seems like an overly complex design for low cost, fault tolerance and reliability.

It is hard to tell, but did that crank look like it had failed rod bearings?

It certainly looks like the design/analysis budget was milked well.

I am seriously disappointed that the NASA Glen communications office failed to locate this presentation.

Thanks for posting this.

I think the rods are bolted to the gudgeon pin from below the piston although nothing is particularly clear from the resolution of the photos in the report. Likewise on the big-end journals...

Yes, I agree it's way too much adventurous design with features that should have been tried (and probably discarded) in a single cylinder test engine program.

Having said that, the two-stroke diesel concept has some characteristics that lend themselves to "unconventional" design solutions. The lack of load reversal on the gudgeon pin is one area that causes grief and requries innovation.
 
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My guess is that NASA, as well as others looking into alternative GA propulsion, have abandoned all fossil fuel engine development in favor of electric.

The plug was pulled on this long before the electric bandwagon had started up. The applicable, available technologies are great, if you want to do short duration pattern work alone. There's plenty of other references around regarding issues with battery cooling, energy densities, etc. Can't wait to finally be wrong here but I probably wont get to see it, let alone, get a ride in one.

@AndyRR. Great find. It seems those involved went to great lengths to hide such "evidence".
 
I'd jump all over the electric bandwagon. Just need comparable range and capability. No more exhaust staining or leaks, no more oil changes. My favourite part is no more mess from dirty slimy stinky hydrocarbons leaking out of every little hole it finds.
 
Gross

My comment about electric airplanes is that the takeoff and landing weight is the same. Takeoff at gross means landing at gross. ( and go around at gross). Its going to be a different experience.
 
That will be interesting for bigger planes. For us, not so much, since max takeoff and max landing weight are the same. A circuit burns 5 or 10 lbs of fuel, so hardly noticeable. The bigger problem will be aerobatics. Typical way of reducing weight for aerobatics is to leave baggage on the ground and leave fuel in the truck. Unless there is easily removed battery packs or sections, this will pose a problem.
 
That will be interesting for bigger planes. For us, not so much, since max takeoff and max landing weight are the same. A circuit burns 5 or 10 lbs of fuel, so hardly noticeable. The bigger problem will be aerobatics. Typical way of reducing weight for aerobatics is to leave baggage on the ground and leave fuel in the truck. Unless there is easily removed battery packs or sections, this will pose a problem.

Smaller battery packs, less time in the air, lighter weight. It's a trade that many aerobatics folks will make.
 
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