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AC Aero Engines

rongawer

Well Known Member
Hey folks, have you seen these? Pretty sexy looking.
http://www.ac-aero.com/jet-a/

Compression ignition V4 that weighs 137kg dry weight and makes ~350 hp, and a train engine's worth of torque (>650 ft-lbs at the prop). Looks like fun.

I've been communicating with them and thinking about this for my RV10.
 
What engine speed do you need to make that much power? That looks kinda like a gearbox up front.
 
ANY PIREPS on the AX 50 cylinders?

Does anybody other than Kevin Eldridge have experience with the AX 50 cylinders on Lycomings yet?
 
Compression ignition? Certainly looks like a pair of spark plugs on each cylinder...
 
Um...

It looks to be a "combined cycle" engine. Reading the literature, it seems to be a two stroke engine that burns jet A. I didn't see anything that said it was a compression ignition engine...though I may have missed it...
 
It's a It is a stepped diesel which uses a spark plug for ignition and has dual plugs for redundancy. I understand they have prototypes in operation, but nothing in production yet. The design is actually over 100 years old, but his use of an integral gearbox and cooling jackets are innovative. I hope he makes it to production. It would be a very torquey engine, efficient in a lightweight package.
 
Yes...

Yes, sure looks like a good fit...

BUT

So did the Deltahawk, 6 Cylinder Pmags, The Dynacam, several small turboprops, etc.

Hopefully, this one will make it!
 
The Higgs is a stepped cycle, spark ignition engine.

This seems very promising especially for the RV-10

....and the RV-14??
Good to see more and more of these new engine developments that don't use 100LL. I still have a hard time understanding all time and money being spent on trying to develop a "special fuel" for existing aircraft engines. Spend that time and money on developing a new engine that burns Jet A, a fuel readily available world wide. We put a man on the moon...surely an engine for a small airplane can't be that difficult. :rolleyes:
Good luck to these guys!
 
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Any engine will make plenty of torque if it's geared low enough.

For an existing airplane design, it suggests that an optimum prop would be fairly long. If so, that introduces ground clearance issues. Or it could have a large number of blades.

Dave
 
It?s all about the money

The problem is that the development costs are astronomical...and the potential market return is tiny. Putting a man on he moon cost about 14 billion dollars IN THE 60s. There were many thousands of people involved and it took the government to finance it. Designing and going to production on a small airplane engine, well, if the numbers were favorable there would be many more choices available now...
 
Any engine will make plenty of torque if it's geared low enough.

For an existing airplane design, it suggests that an optimum prop would be fairly long. If so, that introduces ground clearance issues. Or it could have a large number of blades.

Dave

The prop currently be proposed is the MT-5. It?s a 5 bladed composite, but will handle the pulses. It weighs in at ~85#, so not bad. Should be smooth.
 
Prop

85 lbs for the prop? Thats about 30 lbs more than my MTV9 which is 12 lbs more than the recommended MTV12. That weight out on the nose of the -10 may be an issue...
 
....and the RV-14??
Good to see more and more of these new engine developments that don't use 100LL. I still have a hard time understanding all time and money being spent on trying to develop a "special fuel" for existing aircraft engines. Spend that time and money on developing a new engine that burns Jet A, a fuel readily available world wide. We put a man on the moon...surely an engine for a small airplane can't be that difficult. :rolleyes:
Good luck to these guys!

It?s not a question of ?is it possible?, it?s a question of ?can we afford it?. A brand new engine that can slot into place where a Lycoming went but burns Jet won?t be cheap to develop, and even if every light airplane in the US bought one you?d only be looking at 160k or so units to amortize all that development expense across. My guess is that the final experimental version would run about what a new Lycoming does. And that?s not even accounting for certification costs, which would probably add 50% to the development cost, and then another 20-30% for the STCs required.

Most of the GA fleet is not going to drop money equivalent to 1-3 times the current value of their aircraft on a new engine.

By contrast, a 100LL replacement is expensive to develop too, but its sales are in much smaller and affordable units over a longer time. It?s easier for the fleet to absorb a 20-30% increase in fuel costs than capital outlay exceeding the aircraft?s hull value.
 
The prop weight works out since the engine itself is so much lighter. I can share some numbers offline if you'd like to see them.
 
The problem is that the development costs are astronomical...and the potential market return is tiny. Putting a man on he moon cost about 14 billion dollars IN THE 60s. There were many thousands of people involved and it took the government to finance it. Designing and going to production on a small airplane engine, well, if the numbers were favorable there would be many more choices available now...

It?s not a question of ?is it possible?, it?s a question of ?can we afford it?. A brand new engine that can slot into place where a Lycoming went but burns Jet won?t be cheap to develop, and even if every light airplane in the US bought one you?d only be looking at 160k or so units to amortize all that development expense across. My guess is that the final experimental version would run about what a new Lycoming does. And that?s not even accounting for certification costs, which would probably add 50% to the development cost, and then another 20-30% for the STCs required.

Most of the GA fleet is not going to drop money equivalent to 1-3 times the current value of their aircraft on a new engine.

By contrast, a 100LL replacement is expensive to develop too, but its sales are in much smaller and affordable units over a longer time. It?s easier for the fleet to absorb a 20-30% increase in fuel costs than capital outlay exceeding the aircraft?s hull value.


Thanks Bob and rmartingt for the insight. Too bad money gets in the way of advancing technology, but I understand. No existing company would want to touch the numbers you discussed with a 10 ft pole.
Good luck to the new companies like the one introduced in this thread. Hopefully some of them will eventually have success and gain momentum,...or at least "rattle some cages".
Shawn
 
A new motor which had high power to weight ratio and can run on Jet A would be a home run considering 100LL issues facing general aviation. Hope this powerplant makes it to market.
 
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