Possibly a silly question... car engines?
That looks nice! Might well be the kind of engine the o/p was hoping for. Not certified, though!
And no dealers in Europe, as yet. US$ <=>euro rate is also less favourable than it used to be, I think?
13.000 us$ seems like a neat price though, I should think even a basic Rotax 912 (80 hp, non-certified) is more expensive.
And no dealers in Europe, as yet. US$ <=>euro rate is also less favourable than it used to be, I think?
13.000 us$ seems like a neat price though, I should think even a basic Rotax 912 (80 hp, non-certified) is more expensive.
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Re Wilksch. I thought they had a Wankel engine at one point in the '90s. I may be wrong.
Wilksch Airmotive have a 2-stroke diesel engine. The WAM-120.
People here seem to be saying good things about Rotax reliability, which pleases me as much of what I've heard previously has been quite negative. I don't like the thought that progress in aircraft engines has ended.
Last edited by abgd; 26th Feb 2012 at 15:52.
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My car, when new, could hit 140 mph. Rolling resistance is low and parasite drag is proportional to the square of speed, so the drag on my car at 70 mph is one quarter that at 140 mph, so around a quarter the force at the wheel it is capable of producing. Power = force x speed so with the speed halved the power is reduced by another factor of two, to around 12.5%.
OK so there are fudge factors in there, but it is a ball park figure. Let's add a margin and say that I am using less than 20% of the power to run at 70 mph. OK it was built in Germany, so assume it was made to run well at around 100 mph or about 40% power. Aero engines typically run at around 70% power in the cruise for a sensible balance between speed and fuel use.
So in order to be reliable as an aero engine, my 170 bhp car engine should probably be derated to around 100 bhp. That is starting to look a lot less useful.
I did some work for a motor racing team at one time. They used a very reliable car engine, and of course rebuilt it every race. Working at high power outputs it rarely lasted 6 hours if the race was that long. OK, that is extreme: racing is a tough environment for a car. However it is the end of a continuum of power vs. endurance.
OK so there are fudge factors in there, but it is a ball park figure. Let's add a margin and say that I am using less than 20% of the power to run at 70 mph. OK it was built in Germany, so assume it was made to run well at around 100 mph or about 40% power. Aero engines typically run at around 70% power in the cruise for a sensible balance between speed and fuel use.
So in order to be reliable as an aero engine, my 170 bhp car engine should probably be derated to around 100 bhp. That is starting to look a lot less useful.
I did some work for a motor racing team at one time. They used a very reliable car engine, and of course rebuilt it every race. Working at high power outputs it rarely lasted 6 hours if the race was that long. OK, that is extreme: racing is a tough environment for a car. However it is the end of a continuum of power vs. endurance.
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“People here seem to be saying good things about Rotax reliability”
The 912 series engine has always been very good provided it is looked after by Rotax knowledgeable people. Apply Lyk or Cont engineers with no Rotax knowledge and there are problems. When I made my decision to build my MCR 9 years ago LAA eng considered it the most reliable engine in the fleet, which was one of the reasons I chose it.
Rod1
The 912 series engine has always been very good provided it is looked after by Rotax knowledgeable people. Apply Lyk or Cont engineers with no Rotax knowledge and there are problems. When I made my decision to build my MCR 9 years ago LAA eng considered it the most reliable engine in the fleet, which was one of the reasons I chose it.
Rod1
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Shorrik, I often wonder about these dyno tests and claimed transmission losses. If say 20bhp is lost in the transmission that is about 15Kw. That's a lot of single bar electric fires even spread out between gearbox, final drive and drive shaft joints.
I suspect that the rolling road figures extrapolated to flywheel figures have a sort feelgood percentage built in.
I suspect that the rolling road figures extrapolated to flywheel figures have a sort feelgood percentage built in.
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Slightly off-topic for which apologies but I stumbled across this the other day and found it absolutely fascinating as a study in the mistakes that engineers make. Packard were a car company and their aero diesel set an unrefuelled record (80 hrs+ ) that would be hard to beat today. Some of you might find the article quite interesting.
