Rotax - hand swinging.
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Joined: Feb 2006
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From: Uk
Rotax - hand swinging.
I have been told it is impossible to hand swing a Rotax 912 because you can not generate enough energy for a start; and that because of this you do not need to treat the prop as always live.
As this goes so against the grain of everything I have ever been taught I thought I would elicit some views from those with rotax experience.
Any views or comments?
As this goes so against the grain of everything I have ever been taught I thought I would elicit some views from those with rotax experience.
Any views or comments?
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Joined: Feb 2000
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From: UK
I'd agree that hand-swinging pretty much any Rotax is not viable - they need a high speed to get going, have a gearbox which interferes somewhat, and also generally the prop blades are too darned sharp.
The 2-stroke Rotaxes mostly have an optional recoil starter fitted (a bit like a lawnmower's) which solves the problem.
On a 912? If the battery was flat I'd charge it or jump it, if the starter motor was poorly, I'd fix it. I'd not attempt a hand start.
However, I see no reason not to still treat the prop as live - it's basic common sense, which loses you nothing.
G
The 2-stroke Rotaxes mostly have an optional recoil starter fitted (a bit like a lawnmower's) which solves the problem.
On a 912? If the battery was flat I'd charge it or jump it, if the starter motor was poorly, I'd fix it. I'd not attempt a hand start.
However, I see no reason not to still treat the prop as live - it's basic common sense, which loses you nothing.
G
Joined: May 2001
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It doesn't matter what type of prop aircraft your in or which power plant to be honest always treat the prop as live.
I even do when I with the works machine which is a turbine. I try and keep out the prop arc as much as I possibly can.
If you presume every prop is live they can't bite you and more importantly it ingrains keeping yourself safe when sods law is you forget what type of aircraft your dealing with one day.
I even do when I with the works machine which is a turbine. I try and keep out the prop arc as much as I possibly can.
If you presume every prop is live they can't bite you and more importantly it ingrains keeping yourself safe when sods law is you forget what type of aircraft your dealing with one day.
Joined: Aug 2007
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From: Plumpton Green
I'd agree that hand-swinging pretty much any Rotax is not viable -
Air Accidents Investigation: Skyranger 912(2), G-CCXM
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Joined: Feb 2000
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From: UK
It probably flavoured my own thinking.
G
Joined: Jan 2003
Posts: 517
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From: Kelowna Wine Country
According to my manual the engine requires 300 rpm to start and the prop is geared. There is no special retardation on a magneto for starting. However all that does not preclude an efficient magneto and correct mixture from firing a cylinder.
Jemima is a pusher with wing wires from the deck at the leading edge of the fin. Nothing would induce me to turn over the engine standing inside those wires in any circumstances.
Jemima is a pusher with wing wires from the deck at the leading edge of the fin. Nothing would induce me to turn over the engine standing inside those wires in any circumstances.
Joined: Aug 2010
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From: Ecuador
Joined: Jun 2002
Posts: 630
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From: UK
Seems a popular subject - it was in the 'hand starting' thread only a couple of weeks ago.
Conrad Beale is widely (and correctly) accepted as the UK Rotax guru. On his course, he says it can be done - so it can be done. Anyone saying anything else is wrong.
Read the AAIB report!
Conrad Beale is widely (and correctly) accepted as the UK Rotax guru. On his course, he says it can be done - so it can be done. Anyone saying anything else is wrong.
Read the AAIB report!
Joined: Aug 2010
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From: Ecuador
I am still confused.
If you need about 300 RPM to start a (cold) Rotax 4 stroke; how did the gentleman hand-crank his Rotax in the above described incident?
Would a warmed up engine be easier to hand crank?
Cheers,
###Ultra Long Hauler###
If you need about 300 RPM to start a (cold) Rotax 4 stroke; how did the gentleman hand-crank his Rotax in the above described incident?
Would a warmed up engine be easier to hand crank?
Cheers,
###Ultra Long Hauler###
Joined: Jan 2012
Posts: 366
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From: Below transition level
Assuming ( 
) 300 RPM is the engine / not prop RPM required to start.
Gear redux ratio in Rotax 912 aircraft I have flown ~2.43, so approx 123RPM required at prop.
Also worth considering is that Rotax throttles are sprung open if the throttle friction is lost!
) 300 RPM is the engine / not prop RPM required to start.Gear redux ratio in Rotax 912 aircraft I have flown ~2.43, so approx 123RPM required at prop.
Also worth considering is that Rotax throttles are sprung open if the throttle friction is lost!
Last edited by Fostex; 10th May 2012 at 07:56.
Joined: Jan 2008
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From: The Smaller Antipode
However, I see no reason not to still treat the prop as live - it's basic common sense, which loses you nothing.
Club member chatting to newcomers in the hangar, hand resting nonchalantly on the prop. New Student being introduced to the cockpit, switches off but being shown which key position NEVER to select until ready to start, but did !
Guess what happened !
Fortunately welcoming club member not injured - but he won't touch the prop again.
Murphy is always with us.
There is no special retardation on a magneto for starting.
Joined: Apr 2003
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From: Midlands
I was told by the dealer that sold me my engine that you could not hand start a 912. I have also watched an owner spend 3 hours trying without success. I do accept that it can be done, but the idea that it is not possible has been around for many years.
Rod1
Rod1
Joined: Aug 2010
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From: Ecuador
###Ultra Long Hauler###
