John Cooper wrote: > > In a message dated 00-01-09 14:53:09 EST, you write: > > > Here's my first question: If you turn the prop "backwards" with the mag > > switch 'on' and it hits compression on one cylinder and 'bounces' back > > in the forward direction and slips out of your hands, (putting you > > 'off-balance) couldn't this be dangerous since now the impulse couplings > > on the mags would be active? Of course if the mag switch is 'off' then > > The impulse couplings are not much of an issue in this case. They don't come > into play until about 25 degrees BTDC and fire at about TDC. If you don't > move the prop in the correct direction, starting before they engage and > folllowing through the lag angle (to roughly TDC) then they are not > contributing. HOWEVER, it is possible to fire a plug without the impulse > coupling, by turning the engine through the angle where the ignition points > open IN EITHER DIRECTION. If you don't agree, take a plug lead in your hand > and try it. > > > it would be okay as long as the grounding works properly. > Many one handed pilots can attest to the fact that you should never rely on > the grounded p-leads for anything. > > > Question #2: By turning the engine backwards, the oil pump is also > > turning backwards and not pumping any oil into the engine. Wouldn't it > > be better to leave the mag switch 'off' and turn the prop 'forward' for > > a few blades and lube the cylinders before starting the engine? > > You would have to turn about 50 blades through to move a significant amount > of oil. Some benefits are spreading what ever oil is already in the > cylinders, a quick "Armstrong" compression test, and priming if you have a > Stromberg and no primer, or if you have a primer and don't want to use it. > (You're correct about radials. The bottom cylinder(s) can collect enough oil > or fuel or both to bend a rod.) > > This reminds me of something I saw a couple of months ago. A couple of guys > were getting ready to fly a Cessna 180. One slight old guy was "pulling the > prop through". A 180 is a taildragger and the spinner is about 5 or 6 feet > off the ground. This guy had his arms wrapped around the prop in such a way > that if it fired, it would have cut him in half and flung the parts across > the ramp. Should I have said anything? > > Lefty > > __________________________________________________________________________ ______ > To unsubscribe from this list please send mail to [EMAIL PROTECTED] > > _____________________________________________________________ > Keep up with breaking news! Join our Hot Topics list. > http://www.topica.com/lists/breakingnews/t/12
Hi Lefty,
If I had been there I would definately have said something! I
would
have 'humbled' myself so as to not come on like a "know-it-all", but I
think I could have made a suggestion without offending or belittling
him. And even if not, SO WHAT, I'd rather he'd get mad at me than to
kill himself.
If he was a pilot he would understand, and if he was not a pilot
he'd
probably not know enough to argue the point.
Personnally, I learned the "leg-swing" technique over 50 years ago
and
I still use it. Even if you should lose your balance and fall to the
ground, you'll be away from the prop. I've heard about every arguement
there is about using different methods on a 'small' and low compression
engine but I've started all types of singles and even some twins with
three bladed props and got them started and never even had a 'close
call' with a prop. It works for me so I'll keep on using it.
Bob Saville
N3396H 415C
Eugene, OR
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