Restarting a hand start engine when airborne

[LowNSlow]

I was just watching the 2001 London - Sydney Air Race and marvelled at the nerve and stamina of all the competitors.

One comment that Maurice Kirk made that caught my interest was in reference to restarting a stopped engine. He had coasted out and was at 5,000' when his engine stopped as he transferred fuel to his main tank. He immediately put out a Mayday and put the Cub into a near vertical dive and fish tailed with his rudder to "put more force" onto the, by now, stationary wooden propeller. The engine re-started, he cancelled his Mayday and the crew of a 182 (?) from the race who had diverted to orbit him and monitor his position (well done chaps) continued on their now ruined leg with Mr. Kirk's thank you's ringing in their ears (I assume).

I have never heard of fish tailing in a dive to increase the forces on the prop blades. I can see that as the aircraft yaws left the the right hand blade will see an apparent acceleration but surely that would be compensated for by the deacceleration of the left hand blade resulting in the same overall turning force being applied to the crankshaft. This assumes that the prop has stopped horizontally rather than vertically of course.
I can only assume that the purpose of moving the tail left and right and thus varying the pressure on the blades is to put increased pressure on the blade that can flick the engine over a compression?

Is there anybody in Ppruneland who can clarify this for me please? My aircraft has no starter but it does have a metal prop which will at least keep turning longer than the lighter wooden equivalent :D
This would at least give me longer to re-start my brain and get the feet dancing in the event of an engine failure :eek:

[Shaggy Sheep Driver]

I was taught this air-start method for the Chippy (in the 20+ years I've been flying it, it hasn't always had a working electric starter). Stall turns to the left are a good way to unintentionally stop the engine in flight.

140 knots (which requires quite a steep dive, especially to get there with minmum height loss) and fish-tail if it doesn't start to rotate.

Can't help with the theory of why it should work, though.

SSD

[LowNSlow]

SSD it would be nice to know the reasons why it works but I am more than happy to know that it actually does work :ok: :ok:

Here's hoping I never have to do it for real ;)

[Kingy]

I do know that my L4 Cub wont re-start in the air no matter what you do. Of course, I 'only' dived to VNE (100mph)...!

Kingy

[B2N2]

Interesting.....
Never really ocurred to me.
Best guess...the fishtailing(yaw) puts unequal amounts of pressure on the prop-blades, therefore an add. force on one blade and a reduced force on the other might be enough to overcome the compression and get the thing to turn.
Like hand-starting, you don't turn the prop by both blades at a constant speed,no you grab one blade and yank it ...Right?;) ;) ;)

[Tinstaafl]

I'm not sure that the blades are experiencing the 'same' force as each other during the maneouvering. Perhaps they would if they were mirror images of each other?

I would guess that inducing yaw &/or pitch might temporarily alter at least one blade's AoA, hopefully generating enough force to overcome compression if a high speed dive alone is insufficient.

Once turning then normal airflow + blade momentum is then enough to keep the engine turning.

[DB6]

Very interesting topic. Has anyone airstarted a Tipsy Nipper by the way? I keep meaning to try but have always been able to find some excuse :eek:

[Stampe]

Always used to demonstrate this exercise when conducting Instructor courses many years ago.In a Robin DR400/108 fitted with a fairly fine pitch prop it would be necessary to virtually stall the aircraft to get the prop to stop but once stopped it took in excess of 140 knots and a lot of height to get the prop to turn very reluctantly and then only after fishtailing.Definitely the fishtailing (yawing) that got the prop to turn over a compression.I was always diving towards the 1000ft. point for a pre-selected and very suitable forced landing field, suggest anyone practising this takes this precaution.DB6 don,t give you much chance of starting a VW powered Nipper by this method i believe angine stopping during aeros has been a major cause of force landings over the years with the type!!.:eek:

[LowNSlow]

Stampe although you'd planned for a dead stick landing, how relieved where you when the the donkey started running again :D :D

DB6 I don't give much for your chances of air-starting a VW powered Nipper I'm afraid. :( Maybe starting at FL50 would give you a chance :D I must to abject cowardice at attempting this for fun! Fortunately we have a 1,000 ceiling over our airfield and I wouldn't want to spoil another field's quiet day. That's my excuse and I'm sticking to it like glue!!!

Has anybody airstarted a Cirrus powered Auster with a metal Fairy-Reed prop? Knowing what the expected height loss is could be a bonus one day........ SSB what height loss did you get in the Chippy? and ith what prop fitted? I know there is a world of difference between the Chippy and the Auster but there is probably a greater similarity between them than say a C150 and an Auster.

[DB6]

Hmmm, yes. I think I'll continue finding excuses :} .

[bingoboy]

The RF4 team used to worry me a bit as I am sure that they must have had a few engine stops mid routine but never seemed to . AM I right and if so how did they restart the engine (if not then how did they keep them running?)?

[Dan Winterland]

The original engine installalation for the RF3/4 had a decompressor which when pulled, cracked the exhaust valves on the right bank and broke the pneumatic lock allowing the engine to turn. I owned a RF4 which had lost this function after an engine replacement and no amount of diving/yawing would turn the engine.

I used to turn the engine off in good soaring conditions - but you had to have fairly large gonads or very good soaring conditions to do this. I got caught out once - landed in a large field, hand swung the engine and took off again!

Great days! :D

[skua]

Low n Slow

Re the race, from memory it was an Aussie crew in a Partenavia who circled overhead. They were in the precision competition, and were so good they still won the trophy, despite that leg. Maurice was an amazing and stamina-full aviator, but a bit of a pain otherwise.

[LowNSlow]

skua he certainly ruffled a few feathers didn't he! I'm sure there will be a multitude of stories emerging now that he has passed on.

This is a 3rd hand story so the truth level is unknown!! Mr. Kirk arrived in one rather stuffy aeroclub darn Sarf which had a no pets rule which as a vet he strongly disagreed with. Now Mr. Kirk had apparently forgotten that there were half a dozen Labrador(?) puppies in his flying jacket. When he opened the jacket to pay for his tea the puppies scattered to the four points of the compass leaving characteristic trails averywhere. Mr. Kirk was told never to darken their runway again!!

[Dusty_B]

LowNSlow
Whoa there, before the stories get out of hand... check out the obituary - Kirk lives on, it's Maurice Brett (http://www.pprune.com/forums/showthread.php?s=&threadid=83804) who's emigrated to H24 friendly aerodrome in the sky.

[LowNSlow]

Dusty B I'm sure that's a great relief for Mr. Kirk!!!!! Condolences to Mr. Brett's family however.