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Suggestions/feedback for new production engine

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thjakits

Well-Known Member
Joined
Jul 3, 2014
Messages
72
Location
Panama, Rep. of Panama
Hi all,

On the fuel side - did you guys look into a "non-diesel Jet-A conversion"?

What do I mean with this?

Convert a gasoline engine to use Jet-A (....and Diesel if you can accomodate the higher lubricant levels vs Jet-A...) in a spark-ignited, direct injected way (...NOT in a "diesel"way - compression ignition) - You would NOT need the sturdier engine requirements like a true Diesel engine.

Direct injection: Today's car diesel engines use very high injection pressures with multiple and metered injections per stroke/injection event. These pump/injector/nozzles are able to provide a extremly fine mist and excellent operational safety (today's car diesels depend mostly on regular oil and filter change and the use of a quality oil...)

It should be very much possible to start a multiple spark event at the same time or slightly earlier than the fuel injection. Engine compression ratios would be the same as with the gasoline engine (so compression should harldy ever be enough to ignite the fuel - ....besides that ingintion sparks should start BEFORE fuel get's added)...

If you can offer a huge GA fleet that depends on Avgas into being able to use cheaper Jet-A, you should have a winner!
Furthermore, many regions in the world do not have Avgas.....

With your present engine it might require a new head design to accomodate the direct injectors - I understand these need some solid seats/bores to help with the injection pressures - avoiding "inflation" of the injectors during the injection cycles (pressures are variable from about 180 bar on pre-injection up to 2500 bar on the main-injection cycles (about 2620 psi up to 36000 psi)...

You already noted that you use OEM hardware, so you might be in the position to source the needed injection systems too. Furthermore I would guess, that for a "gasoline engine" to run Jet-A, you might get away with less pressures.... I believe BOSCH might be the leading injection systems provider for CR diesels....

The 2 critical points IMO are the head design regarding the forces around the injector (VW engine manual provides some idea how tight the injectors are installed!!) and possibly the longevity of the sparkplugs....
All else should be a problem at all anymore....
Sure - you might want to optimize the camshaft, valve sizes, etc....
[If I am not mistaken, this was tried in the 80s by someone, but Diesel-injection technology wasn't there yet to provide a fine enough mist and exact enough timing for the injection events - both are things long since evolved!!
Common Rail Piezo Control allows for up to 7 - probably more by now....- distinct injections per cycle, each custoized to the requirements and situation at hand...]

Obviously the question is - IF you go through all the trouble to convert to Jet-A, why not use a diesel engine?
Answer: WEIGHT! They are still not there to provide a reliable aviation diesel engine at the desired power level.
The RED A03 is a bit too big for your 172/182 size machine, also the prize is way out there!
The idea is really just to find a way to use Jet-A in a gasoline engine and with that open up Jet-A to the GA client and the countries that do not have Avgas....

There are even a number of gasoline engines with direct injection by now - though I doubt that these injection systems would be able to atomize Jet-A/Diesel adequately and/or fast enough.... so a diesel-injection system would be necessary....

At the point where you guys are, this might not be that much more to do, to try!
As mentioned elsewhere - you will run int a lot of finacial trouble to try to get to market.
With a Jet-A/Diesel eating engine on the other hand - you could have a winner at hand!

Cheers,

thjakits
 

akwrencher

Well-Known Member
HBA Supporter
Joined
Oct 16, 2012
Messages
1,292
Location
Gustavus, AK
Designing/building a spark ignited engine to burn Jet A/diesel can, and has been, done. To do what you are suggesting is not simple, quick, or cheep, by any definition. Those injection systems, at least the ones I'm familiar with, tend to use high pressure oil systems to build the fuel pressure up to those levels. Not something to just bolt on to another engine.

Note: this is a deep rabbit hole. Let's not detail the OP's thread with it.
 

PTAirco

Well-Known Member
Joined
Sep 20, 2003
Messages
3,576
Location
Corona CA
One way is do it like Robinson helicopters. They carry no insurance. The question is if it’s certified, what certification are you going to sell it under? If you use FAA and convert it to EASA, it could still return back to the US. EASA only would end up staying somewhere else. Canadian May or may not keep it out.
If I ever get to the point of producing something aviation related I would ensure that everybody knows I have zero insurance and that anything of value I have is protected by othewr means. Ambulance chasers won't touch me.
 
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