Inflight re-start on non-electric engines

[mtw]

I have read articles about re-starting hand propped engines by diving the plane to turn the prop. I most recently read an article in AOPA Pilot by Barry Schiff and his experience years ago with a Champ. He did not get a re-start due to the prop sticking on the compression stroke and landed off airport.

I wanted to know how many of you with a lot of experience have done this and if it is a common practice.

Thanks,

Todd Wilemon
Aberdeen, MS

[N86250]

I did it in an old 85 h.p, Chief years ago when I was younger and dumber. In retrospect, it would not have restarted were the engine not worn out and low, low compression. I exceded the redline 129 mph before it started to windmill. I had visions of 30 year old fabric departing the airframe. My hemhoroids left clutch marks in the seat upholstery. I have no desire to try it again. Should I have an engine quit and the prop stop, I would concentrate on the forced landing and I would not even think about diving to try a restart.

[mtw]

Sounds a little too exciting!

Todd

[joea]

This is where a McDowell starter would help. At least it would get the prop over the compression and once there it would turn and probably start.

[Rich Valler]

A few years ago my then partner in our (now my) non-electric Champ was doing his biennial hour with an instructor and had the engine stop when demonstrating a power-off stall, very sensibly positioned overhead an inactive military airfield just in case of such an eventuality. The instructor took over and dived to VNE (and perhaps a little more…?) but the prop did not turn over at all in the dive; however, when pulling out of the dive, the prop did turn over, and the engine restarted. Maybe someone on here can figure out the aerodynamics behind that! I believe neither of them particularly enjoyed the experience …..

Engine: C85 in good average condition
Prop: Sensenich (Metal)74CK-2-44

Rich

[joea]

Rich,

Only idea is that the "G" force when they pulled up had enough inertia to move the metal prop blade past the compression stroke and allow it to windmill and start. If this is what happened doubt it would have happened with a wood prop.

Joe A

[Clive]

I've never had it happen myself (touching wood ) but I thought it made a difference if the prop was wood or metal. Metal props presumably being more efficiently shaped for the slipstream to get turning.

Mine's wood anyway so even if it's true, it won't help me. Maybe it is more dependent on the state of the compressions.

[CptKelly]

Does airstarting a PT6 count?

Mike

[Orlan H Franks]

I have intentionally stopped the engine/prop on our 7AC-CONV (C85-8, metal prop) to establish procedure for air restart.

Here are the results: With the PROP STOPPED, a dive to the 115 +/- mph indicated is necessary to get the prop to turn. Don't dally around, get the nose down and fly it. I see about 2 full rotations before the mags catch with throttle initially 1/4 opened, mixture rich, don't flood it. Follow immediately with a gradual pull-up to about 80 mph and throttle about 80-90% open. Fly it at cruise until you have stable power output. DO NOT ATTEMPT AN AIR RESTART UNLESS YOU HAVE 1500-FEET AGL. That will just leave you enough altitude to re-establish normal pattern procedures. I make EVERY LANDING AS AN EMERGENCY PRACTICE.

If you do not get a engine restart the 7AC gains about 10% better glide ratio with the prop stopped vs wind-milling prop in the 50-60 mph range. Forward slips produce more decent than engine-on forward slips. On dead stick landing the roll-out is slightly longer because of reduced drag in the 50 mph range. The rudder is less effective without the prop-wash assist in directional control. On touchdown, get the nose pointed into the wind ASAP and stop.

I've only had one forced engine out landing in the 7CCM and 7ACs out of 1,500 flights. Don't ever take off on an auxiliary fuel tank! Fuel flow is insufficient to feed full power take-off requirements.

If you go try it DON'T SHOCK COOL THE MILL - THEY WILL SEIZE UP. You will need some 60-70 mph powered gliding to get 20 degrees or more off the engine temp. Orlan

[Quax1]

But,whatever you do... Do not try this at home!
http://www.pipercubforum.com/handprop.htm

Mike

[jkvincent]

Here's another important suggestion, if you nose dive at +/- 115 and don't get it started,
use that airspeed to climb back up a bit to a slow, stable glide to give you more time
to find a place to put it down.
Jim

[shorty]

Here's another important suggestion, if you nose dive at +/- 115 and don't get it started,
use that airspeed to climb back up a bit to a slow, stable glide to give you more time
to find a place to put it down.
Jim

Yep! If you have airspeed you can get altitude, and vice versa. Ol' Bob Hoover has demonstrated this on numerous occaisions.