Maybe the picture was in autoreply's post #79?Somewhere I've seen a photo of a prop that folds forward.
I'lll confess to thinking of the same thing during the Beetlemaster discussions. It is tempting--you just need the power for a minute or two. The setup isn't very complex, you just need a way to get additional fuel added when you trigger the nitrous. It's simple with EFI, only slightly more complicated with a carb. Still, it's "another thing," and it's just a whole lot simpler and safer to design the plane so that, when an engine fails, the pilot can keep flying the plane with the controls he is familiar with. And, of course, boosting the one good engine does put it at greater risk of failing (just when you need it most).I wonder if the one of two engines out scenario might be improved by a small tank of nitrous for emergency use only.
So we are on the same sheet: How are you analyzing performance, what HP engines did you use, what prop efficiency did you use, and what was your criteria for inadequate engine out performance?The twin engine configuration doesn't work out because the engine-out performance is so poor.
I'm surprised. Where did the main landing gear end up? With two engines at the front of the wing, a passenger (if any) under the wing, fuel (if any) in the wing center section, and the pilot out front I would have thought it would work. Well, we always have the old standby: move the very heavy battery to the nose.Three engines might work if we can get the firewall forward (and aft) weight down to 75 pounds. I tried the OV-10 configuration with an aft centerline engine on the back of the central pod. The (empty) weight and balance didn't work so well - it kept falling over on its tail when the pilot climbed out.
Howdy, stranger! It's good to see you here.
I'm pretty sure most twins (if we look at all registrations) can climb out on one engine (though admittedly I didn't go through the registry and count by type certificate ).Most twins are not able to climb out after engine failure on takeoff.
I mean in terms of complexity and parts count.No, a small $1000 electric boost is an alternative to nitrous. Nothing like an electric aircraft.
What about water/methanol injection? IIRC that has a cooling effect, or could you not carry enough of it to matter?I would not recommend Nitrous oxide as a power booster outside of race applications.
The sudden spike in heat can cause piston failure both by melting, and by expanding the rings quickly so the ends bind, often breaking the piston.
Most twins have two engines because that was the only cost effective way to have enough installed HP to drag the airplane into the air.Most twins are not able to climb out after engine failure on takeoff. The actual purpose of the two engines needs to be specified. Is it safety on takeoff or safety on long overwater crossings.
The problem is that engine prices go up very steeply as the power increases.I think it would be better to have enough extra HP so that the remaining engine(s) give a good climb rate without any extra mods or add on's. That way the climb would be pretty spectacular with all engines operational.
The Hondas are undoubtedly nice engines, but IIRC (working from my hazy memory) they haven't been favored for projects like this due to some peculiarity of the spark, governor, or induction system. Id be pleased to find out I'm wrong.Personally, I'd go with a name brand engine if I was going to have to bet my life on it. Honda GX690 V-twins cost under $1,100 each from a place like Northern Tool and make about 21 hp right out of the box. Take of the cooling fan and shroud to save a little weight and gain a pony or two if tractor mounted (leave the fan on for pusher), add an Ace Aviation 1.8:1 redrive (about $800 each delivered) and Ultra-Prop ($350 each). So now you've got twin engines and 42-44 hp of quiet, four-stroke power complete with props for about $100/hp. If the dead engine windmills with one off you could install some sort of manual, cable, operated prop brake on each. You need a light, clean design, but it doesn't have to be a sailplane. Easiest solution might be to take a modest, two-seat pusher like a Kolb Firestar and set it up as a single-seater with one engine in the standard location and one on the nose.
View attachment 75992