Brent_Brown
Platinum Member
Looks like a Exec body was used for this cool gyro it has a 1100cc BMW boxer motor for power.
<br><br>Well, Paul, we dunno what gearing they have. That scooter engine would have to make its HP at a bazillion RPMs. Depending on what the prop shaft gears down to, you might be forced into a small prop to keep away from compressibility in the tips. (Carter did some inadvertent research in that domain back in 1998-99). <br><br>I've always wondered why no one in XA/UL ever used a planetary gearbox to provide counterrotating props. (Maybe someone did and I didn't know). Designing the gearbox is straightforward enough. Doug Schwochert designed and built a simple gearbox to reverse the output of a Solar turbine; Jim Stewart (I think it was him) designed a great gearbox for auto conversions. Why not a CR prop gearbox?<br><br>The trade-off downside on the 4-cycle Rotaxes is maintainability and warranty. You know, if you burn cylinders in a fresh Continental, there is a pro-rata warranty (BTDT). Do it in a Rotax and "esta tu don mierde" as the excitable fellows down south say. ("you're Lord Ca-ca" more or less). Or K MAGYOYO as the Army acronym put it. Even Rotax OEM customers get blown off for parts and service... which is why you can't buy a new plane with a certified 912 any more, the manufacturer redesigned the plane to use a different motor. <br><br>If you lunch a Soob, you buy a new Soob. No warranty at all in this application. <br><br>If you compare a Soob with a VW, the Soob weighs more but makes twice the power. Soobs are more properly compared with aero engines of equivalent power, like a 320. (and then, where's the weight benefit?). I'm wondering if an O-235 would be in interesting choice for a gyro. I'd have to look up the weights. <br><br>Carter has run LS-1 Corvette engines with some success in their larger, heavier machine. An earlier attempt to use a auto racing V-6 failed miserably. <br><br>cheers<br><br>-=K=-Looks as if they decided to preserve a favorable thrust alignment, picking a small, multi-blade prop at the expense of some efficiency.