Gum flappen

[chuckthedog]

Aaron,

OK 75 to 80% lets see 280HP - 20%= 224HP-

30% for reduction If I remember correctly a straight spur gear configureation eats the least energy= 156HP I think a 0-320 is 150HP and a lot less moving parts. Things to go wrong.

I had a 320 Brake HP Mustang a while back and put it on the Dyno and it had a whopping 54 true HP at the back wheels.

I guess I should have had that trany and rear end you were talking about.

As for experimenting. I am all for it. I do it. You just have to walk before you run.

[JakeC]

Chuck,

 

Are you saying that the O-320 has less moving parts than the Rotary?

 

Jake

[Aaron]

I think you're getting confused with the numbers here.

 

if you car's engine was truly generating 320 Hp and the wheels were putting down only 54 Hp then something was absorbing 266 HP, but that's not likely to be the gearset. Maybe your clutch was slipping, or maybe there was some other problem and one or both of those numbers is wrong.

 

Think about it, how could the gearbox absorb 266 HP? Thats 200 kilowatts of heat. Thats like having 200 1000 watt bulbs dissapating heat energy under your car-that's a LOT of heat to be generated by a gearbox.

 

The highest driveline losses seen today in the automotive world are on AWD cars like the Audi Quattro system, and those are about 25% (due to 3 differentials) FWD economy cars get around 10-15% driveline loss, and a PSRU loses even less because it's only a planetary gearset, no differential.

 

If you look at piston engines they are 30% efficient at converting the chemical energy of gasoline into motive force, maybe that's where you came up with that number?

 

As for "alot less moving parts"- you're wrong again. If you have a 4 cylinder engine you have: 4 pistons moving, 4 wrist pins, 1 crankshaft, 1 camshaft, timing chain, at least 8 lifters, 8 pushrods, 8 rocker arms, 8 valve springs, 8 valves in the engine: 55 parts moving. Much of it at very high service temperature, which thins out oil films.

 

In a rotary: 1 eccentric shaft, 2 rotors: 3 parts moving

 

Add a 4 or 6 planetary gear set and how many parts do you have? less than 15 total?

 

Based on your own logic, less parts moving equals less things to go wrong, right?

[chuckthedog]

JakeC,and Aaron,

You are right. What I was trying to say was

if it aint broke don't fix it.

As for the 320BHP and 54HP these are two differnt animals. BHP is not real HP.

[marbleturtle]

Is this a bad time to bring up torque again?!?!?!

[Aaron]

BHP- Brake Horsepower, is the power required to keep an engine from accelerating past a given RPM. The torque is measured and converted to BHP (BHP=torque*rpm/ 5252) and it's the constant RPM power of an engine. While your comments certainly apply to automotive applications, an airplane is a constant speed application of an engine, so I'm missing your point.

 

Are you saying the BHP measured for a Lycoming is different from the BHP measured for a Mazda? How?

 

Me I love reinventing the wheel, that's why I'm so interested in building- I want my plane to be truly mine, and that includes selecting the right engine for me. At the same time, I can certainly understand the desire to plug in a proven engine and GO.

 

Now on to a completely different topic. I've heard plenty of reviews on 1 and 2 year old planes, but never a 12 year old EZ. What's the long term upkeep like? If you were to do anything differently, what would it be?