One-engine failure on take-off with JPXs

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Postby ger » Sat Jul 21, 2007 11:49 pm

One-engine failure on take-off with JPXs

If one has a one-engine failure on take-off (shortly after rotation, say) with JPXs on a Lazair, is it possible to keep flying (climbing) to do a go-round? Or is there likelyhood of a wing-over-nose down crash because the dead-engine wing stalls?
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Postby daffy1029 » Sun Jul 22, 2007 11:09 am

Hi ger,
I used to have JPX engines back in 1984, and found that in the winter time (when I weight about 180lbs) I could maintain altitude on one engine. The cold dense air gave me good lift, and good power. In the summer, no way I could maintain altitude (unless you hit a thermal). And as far as turning, you are suppose to turn towards the good engine, to prevent wing stall. Well I tried this, and it does not want to turn, with the engine at full power. I found that if you need to turn, cut the engine back to idle, make your turn, then apply full power, and at least you will have a very long glide (and time to make a decision), with one engine at full power. I use to play with one engine off, over a very large field to get to know how the plane reacts. I had two surprises earlier, where one engine quit on me, and was lucky I was high enough to make decisions on how and where to land. I always look for open fields when I fly now, because you just never know. It is unlikely both engines will quit at the same time, so it's nice knowing that. Daffy ;)
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Postby Shannon » Tue Jul 24, 2007 7:15 pm

This stock "unbeefed" Series III with JPX's and bubble fairing had excellent single engine performance (climb) with a 170lb pilot.
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Postby uscgairdale » Tue Jul 24, 2007 7:57 pm

I (155 lbs) can just maintain level flight with one engine on a stock series III so would think that with JPXs a heavier pilot should be able to climb fairly well. Maybe not like a rocket, but you could get yourself out of a jam and to a suitable landing site.

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Postby JPXman » Tue Jul 24, 2007 11:09 pm

Speaking from personal experience:

in the summer, me (290lbs at the time) could not climb on one JPX engine. had a gradual descent.

my gross weight was about 650lbs (my lazair was heavy with EC, chute, instrument pod).

if you had a nice bare bones series III with JPX and a 170lb pilot, you'd gross in around 440lbs. that is 70% of the weight.

the jpx provides 85 pounds of static thrust, the rotax with biprops about 55 or 60. so the rotax provides about 70% of the thrust of a JPX at no airspeed, so say 50% at climb speed of ~30mph.

i would take that to mean that a pilot who can fly a rotax powered single engine scenario lazair and maintain altitude could make a JPX powered single engine lazair climb.

I only did a few flights in my series III without the EC with the JPXs and it climbed very well but did not go fast. then a light friend of mine flew it, and i told him to just do a high speed run at half throttle before attempting to fly it. on his first run at 300' he realized he had half the throttle left! he was climbing out at about 3400rpm (4400rpm max) .....a light pilot and a JPX powered lazair are a thing of beauty.

i shudder to think what a rotax lazair would climb like with me in it :$
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