Does it come with a coffin?

This is really a hoot :


"I have to sell it because of an illness. " Read - he's brain dead.

"This is a great flying machine for the price, it won't last long." Read - its WILL crash & burn in less than 25 h flight time.

I loved the “won’t last long comment” too. I thought it was very truthful advertising about the expected longevity of the power train. Maybe we should be ahead of the game and get this thread moved to crash talk?

Why not make one gear so peak power on the engine turns the propeller at 2,700 RPM (or whatever keeps the tips sub-sonic)? Nothing to be gained by gears?

You could either have a 6 speed transmission or install a constant speed prop!

You guys are brutal.

Honestly this doesn't seem like such a crazy idea. Why not lower the engine RPM when you don't need the full power?

Because even constant speed props have a fairly narrow operating range

That's the rub, isn't it? I think the right questions to ask are:

1) when do you not need full power?

2) Ignoring the reduction of power with altitude, what are typical low and high % power numbers? Or, asked another way, what are typical % of throttle settings?

Unlike a road-going vehicle, reaching cruise speed is when we can't further overcome drag, not when we stop accelerating and let off the gas to maintain steady state.

I think an equivalent example might be if we, in a small airplane, climbed at Vy to 3 or 4k agl, then pulled power to cruise at Vy.

I think this is a fascinating subject that most people don't really think about.

Scary! I wonder how many more uninformed decisions were made when he built this? I don’t know the exact rules but I thought the builder has to fly 40 hours with close range of the airport before it is certified. How do you sell it before doing that?

Still a big accomplishment to build this and I admire the people who have built their own airplane.

I think I get what you're saying.

However, you could possibly cruise at 40-50% power. This is not exactly a cross-country plane so if you're just doing a scenic flight you might want to cruise at Vy, who knows. Also, isn't 140hp quite a lot for this little plane?

Based on the graph you showed, it looks like 2nd or (maybe) 3rd gear is about as low as you could go for cruise power but what about the descent? You could easily let the engine chug along at 2700 rpm in that case. Just don't forget to put it back into first gear for the go-around!

Not saying it's worth the extra weight and complexity. I'm probably missing something but I don't see it as being completely crazy, given the choice of engine. It's obviously not suitable for aircraft engines that are already optimized for ~2500 RPM.

It's a paperwork drill, like a lot of things. You need to get what's called the Phase 1 restrictions changed to the new airport. (There are other solutions but that's usually the best one.)

Experimental Amateur-Built has a lot of freedom. Some of the freedom is the freedom to hurt yourself (just don't hurt other people) but a lot of it is the freedom to try something new and different.

Sometimes a powerplant choice has everything to do with what a builder can afford or simply what's on hand. There are some successful and very unusual choices in the last hundred years- as well as many, many unsuccessful ones.

I agree that all those speeds seems like a lot for a propeller drive. Just thinking of the rpm spread of GA props, about 1.5:1 and less is typical. A motorcycle transmission has a much higher spread (as does any automobile transmission). No sense getting rid of the extra gears but at the same time more than two or three of them serve no purpose.

Using the "tried and true" motorcycle transmission is, um, interesting. I'm not questioning the robustness of the unit for continuous high load (either fatigue life of any component or surface wear on the teeth). I am, however, very more curious about torsional resonance. (Most airplane people actually have a very poor technical grasp of these two issues.) I am also curious about what he's using as a thrust bearing.

The STOL Zeniths have exceptionally low stall speeds. The tradeoff for that low speed performance is their glide ratios are similar to hang gliders.


None criticism, just critique, and not necessarily a question of good or bad, it just "is."

Another point worth mentioning. I'm no expert on this subject, but I suspect the gears in the motorcycle tranny are not prepared for sending power to a giant tuning fork with significantly less inertia than the wheel, tire, and brake disc it usually spins.

That's the torsional resonance I mentioned



Although the inertia disparity might not be as far off as it seems- the prop weighs less than the motorcycle wheel and tire but it has twice the diameter. Hopefully the intrepid builder and test pilot have both done their homework.

Oliver and Wilbur you guys are crazy. If man was meant to fly we would have been born with wings.

Bill G.normal people don't need there own computer.

Elon no private company has ever built there own rocket and sent it to space.

people that are innovative are always mocked and ridiculed. This might be the craziest thing anyway has ever built or it might be new and ground breaking. The fact that this guy has built this if nothing else is pretty amazing. Anyone who loves aviation enough to build their own aircraft I will applaud every time.

I want to see a cockpit video of someone working this thing through the gears.


KJ