Its a little known fact that with a bit of enginuity, it is possible to start a Radial engine in reverse !. No I didn’t believe it at first either until I saw the Army’s historic display flight at an airshow at Middle wallop a few years ago.
I wonder if they had to cross the controls as well…teehee.
cheers
Gary
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By: LesB - 8th November 2002 at 20:00
RE: Radial engine running in reverse ?
Keithmac
Sounds like you’ve been there and done that . Weird experience though.
By: keithmac - 7th November 2002 at 19:33
RE: Radial engine running in reverse ?
OK chaps, piston engines of the conventional 4 stroke type will not run backwards, Galdri’s explanation is absolutely correct. LesB is also correct about the Brit. It had a Proteus turbo prop. This had a prop brake to prevent windmilling then there was a wind blowing (a common occurrence on most airfields). Pushing the blades round before attempting to start the engine was primarily to find out if the brake was off – you could overheat the turbine if it was left on during a start. Once the brake was off, if the wind was blowing from the back, the prop could windmill in the wrong direction, to prevent this, the blades were either held stationary until the turbine started to turn them, or they were given a push and you retreated. Which technique you used depended on how brave you were!
KeithMac
By: galdri - 6th November 2002 at 11:15
RE: Radial engine running in reverse ?
In response to YAK11 FANS comments about a radial engine in a YAK 11 runing in reverse for a short time, I’m afraid he is a little bit mistaken about that. I’ve seen the same thing happen on my YAK 55, and what is really happening is that the spark is too advanced during the start which leads the ignition in the cylinders to happen too soon, and it causes the engine to produce a kick powerful enough to turn the engine backwards. But it is deffinatly not running, it is just turning backwards, the engine is dead by this time, and actually, most probably never started propperly in the first place. And to make it absolutly clear, this can happen to any and all piston engines and is not isolated to radial engines. If somebody would like a better description of what is going on, in a step by step description, I will be happy to answear any queastions.
About the comment of some Shuttleworth aero engines actually running backwards for some time, the only thing I´ve got to say about it is that it is impossible!!
Regards,
Galdri
By: LesB - 5th November 2002 at 23:08
RE: Radial engine running in reverse ?
>I’ve heard that the engines on both the Avro Tutor and the
>Hawker Tomtit of the Shuttleworth Collection will run
>backwards.
I remember when I was in the RAF that the start ground crew used to have to hold onto the blades of the Britania’s Proteus engines as they spooled up, the blades “could” start turning the wrong way. Then, when turbine was up and running (you could feel the tug of the blade on your shoulder), you would push the blades in the right direction. Trouble was, could never remember if it was clockwise or anti-clock! Anybody else here ever had to do this?
By: Yak 11 Fan - 5th November 2002 at 22:15
RE: Radial engine running in reverse ?
I’ve seen a YAK 11 run backwards briefly, when it fired before TDC (or something like that). Gives you something to think about when it happens though.
By: Ant.H - 5th November 2002 at 20:01
RE: Radial engine running in reverse ?
I’ve heard that the engines on both the Avro Tutor and the Hawker Tomtit of the Shuttleworth Collection will run backwards.I’m not sure I want to know how they found that out!
By: macky42 - 5th November 2002 at 19:40
RE: Radial engine running in reverse ?
You’re right about two-strokes; oddly enough, to reverse a Messerschmitt bubble car, you stopped the engine and started it running the other way. Of course this gave you more than one reverse gear 🙂
By: munnst - 5th November 2002 at 19:14
RE: Radial engine running in reverse ?
No, no you have it wrong.
The Beaver is going forwards, it’s the egg beaters that are going backwards!
By: Christer - 5th November 2002 at 16:14
RE: Radial engine running in reverse ?
[updated:LAST EDITED ON 05-11-02 AT 04:31 PM (GMT)]It would take a lot of enginuity to get a four stroke engine running backwards, sucking through the exhaust manifold and blowing into the induction manifold!!!!!!
It works with some two stroke engines though. If the idling rpm is adjusted so it only just ticks over, sort of hesitates, then there´s the possibility that it changes the direction of rotation to backwards.
It has nothing to do with the radial design. The main prerequisite is a two stroke engine.
Christer 😉
Edited:
It´s possible that it works with the old radials with an automatic inlet valve in the piston head and a rod actuated exhaust valve in the cylinder head. When the piston decends in a cylinder with a closed exhaustvalve, the automatic inlet valve opens due to the underpressure. The engine can rotate in any direction if the ignition system is adapted for reverse rotation.
It still has nothing to do with the radial design. It´s about direction of gas flow.
A two stroke engine doesn´t require adaption of the ignition system, it runs backwards but not very well.
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November 5, 2002 at 2:20 pm