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Jeff Goin

 

 

Fixing Torque By Hand

04/15/2014 Flying The Parajet 250

See also Paramotor Torque Twist and Crash,

Florida's relentless weather perfection lured us aloft again. I got to try Parajet's newest offering, a Thor 250, water cooled, behemoth with thrust galore. It's ideally suited for trikes or competition pilots powering their tiny little steeds to their maximum speeds. It's the thrustiest machine I've ever flown with a clutch. I love clutches--simply getting off the throttle depowers the prop--much faster than the kill switch.

The machine is surprisingly comfy to walk around with considering its 90 pound heft but you want to have the harness well adjusted.

It has lower than average hook in points which left me, at a scrawny 140 pounds, leaned way back even at the appropriate attachment hole. Not surprisingly, torque effects were more noticeable. I took off at 1/3 power to manage it lest I twist up before liftoff. Heavier pilots won't notice this near as much.

In the certified world this machine would likely come with a minimum pilot weight of about 170 lbs.

Just to refresh, I'm using the term yaw for when your body is pointing left but the wing is going right (opposite of belt drives), a common problem on powerful machines that can twist you all the way around in the risers. Yup, that's bad.

Here's the interesting part. I've done this test before but never to such powerful effect. The machine has offsets on both swing arms to mitigate the yawing portion of torque. But for me it wasn't enough -- I still twisted quite a bit. So once I was up higher, I reached out and pushed on the left riser up at its mallions. The goal being to increase the riser offset so the motor's thrust pushes more on one shoulder blade. It worked extremely well!

If you do that enough you can completely counter torque effects as Alex Varv discovered with his machine. So I tried an experiment.

I've done this before but this time got more aggressive. When powering up to full power, I pushed out on the left riser, essentially increasing the offset by 4 inches. It all but eliminated the torque yaw. Enough so that on the next pass I did it again when climbing out and it made a pronounced reduction in yaw.

Thanks to John Erickson, classy importer of Parajet whose toy trailer is the one to rule them all. He's now also the go-to guy for Pollini motors, too, with plenty of parts on hand.

Tim Kaiser snapped this fly-by showing my hang back angle. This alone with make you want to yaw at higher power settings.

All geared machines make your body yaw right, pushing you out to the right and putting the wing in a left bank.


Remember, If there's air there, it should be flown in!