Jet-fueled airplane Diesel

G

GFOLSOM

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Hello all from ...snowy... Southern California.
I was told about this forum by a Cummins driving friend after a long discussion about aircraft diesel engines. I am working on an idea of converting a gasoline engine to a diesel. (The Rolls Royce factory did it some, but little information can be found online). Anyway, I plan on quietly slinking around for awhile so I can learn more about diesels (driven a Dodge some and a few tractors). With the steady reduction in the availability of aviation gasoline and the eventual elimination of 100LL gas, I really am interested in using Jet fuel, which is readily availiable to run a diesel cycle recip.
More on my situation later...
I'm happy to see such a wealth of "hard-core" technical expertise on this well organized forum and I'm looking forward to some interesting discussions in the months to come.
 
not just no, but hell no...

cylinder pressure in a diesel is WAY higher... there are so many things to consider, and there's no way I'd bet my life on a converted engine while I'm dancing with the clouds
 
im not sure if i would bet mine even on the road rather then when im flying around.. good luck if you do choose to do it and please keep us posted on the pictures and how it flys
 
Even if you could get the compression up enough the rest of the engine would exit in pieces.
 
Good points by all, however...
The Diesel conversion wasn't my original idea.
Rolls Royce did run several of the "Meteor" 27liter V-12s converted from avgas to Diesel.
The Meteor is/was about 60% Merlin (P-51 Mustang/Spitfire) and 40% beefed up new castings.
They put them into some tanks and PT boats and troop carriers etc.
The R/R team basically swapped the 6:1 pistons for 15:1 and then took out the twin plugs per cylinder and replaced them with 1 glow plug and 1 fuel injector and ran the things with mechanical direct injection.
Apparently the blocks were stout enough for this to work with some turbo boost (how much I don't know and can't find anyone who can help with that part). Don't forget that the blocks were designed from the outset to have around 45lbs of Supercharger boost on avgas and frequently run closer to 90lbs of boost in todays privately owned birds (with modern Elec. controls and alcohol injection) (all of that at around 3500RPM, which is higher that I would run a diesel)

The effort is a multi-year project (family finances, you all know...) and I have a couple of blocks so I could blow one up as a mule without crashing the plane.

Thanks again for the interest. As I mentioned earlier, I going to be lurking around while learning.
 
Didn't GM try this back in the mid 80's and had a complete failure trying so?
 
LOL, the GM/Oldsmobile 5.7L diesel was one of the collosal automotive failures. I knew a few people (including my dad and uncle) that had them. It sounds like this is a much better candidate though!
 
I don't see any reason it wouldn't work if the parts are robust enough from the factory and you don't lean on it hard. Oh, and welcome to CompD!
 
What engine are you going to start with? Opposed or an inline? I would be willing to bet one of the I-4 or 6 Walter Lom inverteds would be able to be made to work. Not so sure about a horizontally opposed, Lycomings tend to have weak cranks in the non turbo models. One of the larger Continentals from say a 421 might work with different pistons, but only NA, sdo anything more than turbo normalize it and I wold be worried.
 
Back 8 or so years ago when I was in A&P school I did a report on diesels in aviation. There wear a few companys that were already converting to lightweight high rpm diesels, and you could buy kits but had to re register as experimental. back in tose days, the big worry about diesels in aircraft was not having a fail safe system. Avgas engines run 2 mags and 2 sets of plugs incase one system fails. As of 8 years ago, noone had figured out or implimented a engine with an extra pump and injectors. Do a quick search on internet. You may something certifiable for your application.
 
To answer your question, I thought I mentioned it earlier... but I guess not.
The engines I have are 27L (~1500CID) Rolls Royce V12 Meteor engines. (ground based version of the famous Merlin).
As for redundancy. I am considering using two D.I. mechanical fuel injection pumps (Bosch P7100? Two pumps with 6 cylinders each = 1 engine with 12 cyliners)
I've got a lot to learn about diesels before I commit any parts or money to anything though.
 
Ok, my next question is what airframe are you going to hang that on? And can I get a ride??? :D
 
Somewhere I recall seeing a land speed record challenger with one of the RR Meteor running a quad turbo set up. Not saying it wasn't full of custom parts but at least it survived.

Also with 2 6 banger pumps you would still have no redundancy right? You would need 4 to provide a complete back up.
 
Airplane: P-40 "Warhawk" replica. Mostly carbon fiber. We have a complete set of the original drawings from Curtiss (1938) and have redesigned a lot of things using modern technology with the old "look". I have 4 kids with college funds, so it's maiden flight will probably be 10 years from now - it's a long term love affair.
If you're interested go to:http://p40warhawk.com/P-40sToday/JimDelaney/Replica/Replica.htm
 
Welcome!

Welcome to the 'site.

Dont let the un-knowing hold you back. Aircraft & diesel is nothing that was dreamed up 5 minutes ago. Any plane [ex. C-130 / P-3] with an Allison [RR] T-56 hanging from it can and will run on diesel, now. Admittedly, it is not the prefered fuel for it will smoke worse than a Union Pacific Big Boy on coal, but it can do it.

Some [most] people forget [dont know] that Jet A [JP-8/F34] is kerosene, a mildly more refined diesel that most every non-recip powered engine flying today runs on.

A P-40 would be an excellent choice for this project. My first conern would be weight & balance due to the added weight of stronger parts and redundant fuel injection, if it proves neccessary.

If my memory serves me, there may be one of these converted Meteor engines sitting in a diplay case at the Nat'l Air & Space Museum @ Dulles Int' AP. Might be worth checking out. Might also be helpful sending an information request to RR's archives or a Freedom of Information Act request to DoD or maybe the National Archives/Library of Congress. You say you have 10 yrs to ponder this... so if time is on your side, that's where I would start looking. I may even have personal lead to someone still alive who may have worked on one of these. Will have to check on that if you can tell me what engine was used on B-17s?

Military aviation pioneered this a long time ago. It's only fitting to continue the tradition in a restored Warbird.
Hope this helps.
 
Thanks for your input with the "jet-fuel diesel airplane" posting.
As to your question about the B-17 engines, the prototype used a "Hornet" engine which was quickly changed out to the Wright R-1820-97 "Cyclone" engines which were turbosupercharged to allow high altitude cruising.

You made a good point about the refinement between Jet-A vs. "diesel" fuel. I actually plan on developing the engine with normal diesel 2 since it's cheap and then retune it to truly use Jet-A which is obviously more available at an airport. The whole impetus for this effort is twofold
1) 115 octane avgas is nearly impossible to find, even at a regular airport and 100LL is going to go away soon and be replaced by an unleaded variant and
2) Jet-A is cheaper and readily available all around the world - especially north and we have interest from people oversees to purchase the kits. If the engine is designed as a "diesel" then that opens the market abroad.

The original P40 motors used 115 avgas and several today can run on 100LL and some people have put them into boats cars and truck/tractor pullers using all sorts of fuels. I've always loved that bird, it's like Underdog, or maybe Rodney Dangerfield "...No Respect at all..." most people who aren't really familiar with WWII stuff instantly go to the superiority of the P-51 Mustang; and that grates at me like someone putting a Chevy 350 into a 1928 Ford Model-T... Being a Dodge person (my Dad brainwashed me as a kid) I'm used to being in the minority - and being proud of it. However, I'm not above learning from and/or using the technology from anywhere I can get it, after all there is a good reason Ford didn't have to take any of the government's money and my favorite car was my 1968 Ford 427 Torino Dragster.

As for the weight, I haven't calculated all of the differences yet, but I do know that the original engines had a couple hundred pounds of old fashioned equipment hung on them that wouldn't be needed with today's technology (1938 generator=60lbs, 2011 alternator=8lb. Mags=15lbx2, not needed on a diesel. supercharger=~120lb, replaced by 2 turbos=15x2 etc.)

Thanks again for any help you can find.

I know this is usually a truck forum, but since the diesel engine expertise is so readily available here, that's why I joined. I live in CA now, but am from the mountains of Colorado where the trucks are about 60% of the registered vehicles and it's not uncommon to drive a tractor to the grocery store :) I personally have never owned a diesel, but have been around them enough to know it's well worth investigating their use in my application. I currently drive a Hemi powered Durango, but our next family wagon will hopefully be a diesel truck/SUV conversion, that's why my friend and I started this crazy idea in the first place.
 
W&B will be a non issue, as you stated by removing the old heavy stuff, you can use lighter new stuff. We picked up 25lbs useful converting a Beech 18 to alternators vs generators LOL

Biggest difference between jet A and diesel is BTU per gallon is a bit lower on jet. The fuel is also 'dryer' than diesel without as much lube capacity. Since diesel has gone to ULSD they are about equal now. Chris, the reason your birds smoke so bad on diesel vs Jet A? They are metering the fuel as if it were Jet A, which has a lower BTU as stated, so there is more fuel there than can be combusted in the turbine which equals smoke out the pipe.

For an injection pump, you might look at some of the older Cat diesels on gensets, they used up to 12cyl engines on some, and the older ones will likely be a piston style unit similar to the P7100. From there it's just some math and machine work to mount it to the accessory case and run lines :)
 
Awesome insight about the lube properties. I knew about the difference in BTU, but hadn't gotten to the lube differences yet, althought that's why I am/was considering #2 for the preliminary work. I'm glad to see some fellow aviators on this site.
I'll start up another tech discussion in the appropriate place, since this about the longest "INTRODUCTION" I've seen since watching Pride and Prejudice... with my wife:)
 
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