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  #1  
Old 10-24-2012, 04:45 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,804
Default Hand-propping

Rather than cause thread drift on Paul's thread about the broken starter, I figured I would start a new thread.

So, I've thought about hand-propping my IO-360 angle valve.

The problem I have is that the Whirl Wind 200RV prop is so light that it has no flywheel effect. Add to that, the trailing edge is pretty sharp, so it is hard to get much of a stroke on it anyway. But, I don't know, it would have to fire on the blade that you are pulling through to get it to go to the next blade anyway.

With a very low battery (the reason I would be hand propping) I can not be sure that the Light Speed EI would fire at TDC. If it fired 25 BTDC I think it would cut my fingertips off with the sharp trailing edge. On the rare occasion that I might need to do this, I think I would wish that the other mag had an impulse coupling.

I have hand-propped a O-470 with 2 bladed prop on a C-182. The only thing that made that difficult was that it was 15F outside, and it took a lot of pulls, priming some more every few pulls, to finally get enough fuel vapor in the cylinders to fire. By the time I got it started, I was stripped down to a Tee-shirt.
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Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
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  #2  
Old 10-24-2012, 05:03 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default hand propping

I have hand propped four and six cyl Lycomings with Hoffman and MT two and three blade props, several were 10-1 compression. Also Navajo Chieftain several times. In the day many of the aerobatic airplanes didn't have starters.
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  #3  
Old 10-25-2012, 05:47 AM
JDRhodes JDRhodes is offline
 
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Location: Taylorsville, GA
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Default

Quote:
Originally Posted by jrs14855 View Post
Also Navajo Chieftain several times.
Wow - you da man! I've seen charter pilots run the batteries dead and burn up starters trying to start those from the cockpit.

It's like anything, I guess. Once you know how...
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  #4  
Old 10-24-2012, 05:08 PM
Squeak Squeak is offline
 
Join Date: Jan 2005
Location: Indiana
Posts: 271
Default

Steve, I have hand propped lots of aircraft over my years of flying and thought I could prop about any single engine. Was at an airport 200 miles from home and had a dead battery and tried propping my RV7A 0-360 Catto Prop and it got me on a backfire. Took 30 stitches in left hand and broke my right. It's not worth it!!
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  #5  
Old 10-24-2012, 05:18 PM
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Ron Lee Ron Lee is offline
 
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Default

Steve, if that occurs, charge the battery. How long would that take?

Then to prevent the change of it happening, install some sort of warning system if the master is left on.

Replace battery before it becomes marginal.

Consider this like get-home-itis. You have two options:

1) Do what is needed to avoid hand-propping even if it means a delay in getting somewhere, or

2) Risk serious injury or death.
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  #6  
Old 10-24-2012, 06:14 PM
David Paule David Paule is offline
 
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Location: Boulder, CO
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I'm pretty sure that hand-propping only gets you one cylinder to fire in any event. And you could wear cheap work gloves when propping it.

Just be careful.

Dave
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  #7  
Old 10-24-2012, 06:37 PM
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Ironflight Ironflight is offline
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Default

Yeah....I think hand-propping your set-up might be beyond my comfort level Steve. I am happy giving a 360 a go if it has Mags, a two-blade prop, and is a tail-dragger (and the -6 sits low enough as a tail dragger that it was about on the Go/No Go line for me). I'd have hand propped the Val when it had Mags, but with the P-Mags, I'd have to think about it. In our case last weekend, it wasn't a matter of charging the battery or jumping - we had no starter, so we were lucky that it was a simple engine/prop combo.

And just to put it all in perspective, I grew up flying Cubs - hand propping was the first thing I learned, and it is almost second nature. Still scares me if if I don't have the right conditions!

Paul
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  #8  
Old 10-24-2012, 06:49 PM
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RV8RIVETER RV8RIVETER is offline
 
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We have the same set-up, only our angle valve is the dual mag kind. I defintiely would not want to hand prop it.

As a safety note. It is very easy to hand prop, even accidently. To set the scene, our RV-8 was in the hangar, top cowl off, throttle idle, mixtured cut-off (as it was shutdown), hangar door closed and spinner 10 inches awayfrom the inside of the door. My partner was working on our mag, one side quit firing and he simply moved the prop. Bang, the engine starts immediately and runs for about 2 seconds. Needless to say, scared the #$%^ out of him. Turns out he had left one of the mag switches on. The only thing that saved him was the plane was chocked (he was between the prop and hangar door) and he always treats a prop like the mag is hot.
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Last edited by RV8RIVETER : 10-24-2012 at 06:51 PM.
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  #9  
Old 10-25-2012, 01:02 AM
scsmith scsmith is offline
 
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Location: Ashland, OR
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Default Lots of good experiences/lessons here

Ron has the right idea. Dead battery from leaving master on.

So, I put the charger on it, and after an hour, the battery was partly charged, but not enough to crank the engine. So, we are still waiting around.
This is when the thought comes, to hand-prop or not.

The LIght Speed will fire at TDC when hand propping PROVIDED there is at least 6 volts to run the controller. If the voltage drops below 6 volts, I'm pretty sure it reverts back to the static timing, 25 BTDC. So that is the risk.

Having a very light-weight prop was the deciding factor for me - there is just not enough inertia to reliably get it to follow through, so you have to be that much more positive in your 'connection' to the prop, which increases the risk of bad things happening, among the experiences cited here.

So my decision was to wait another 2 hrs ( I have a small charger) and then it started. My wife was not very happy about the 3 hr delay, but I was happy to still have all my fingers, no dent in my forehead, and my biceps muscles still attached to bone.

Funny, a wood prop on a C-85 never seemed like a problem, but a 72" carbon prop on an IO-360 just isn't enough.


Quote:
Originally Posted by Ron Lee View Post
Steve, if that occurs, charge the battery. How long would that take?

Then to prevent the change of it happening, install some sort of warning system if the master is left on.

Replace battery before it becomes marginal.

Consider this like get-home-itis. You have two options:

1) Do what is needed to avoid hand-propping even if it means a delay in getting somewhere, or

2) Risk serious injury or death.
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 635
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2020
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  #10  
Old 10-25-2012, 03:12 AM
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Ron Lee Ron Lee is offline
 
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Good to hear a positive outcome Steve.

I have had enough delays traveling commercial aircraft and my 6A that I accept delays. You can't let a trivial three hour delay lead you down the decision tree to a bad outcome.

Monday I was flying United from Michigan to COS via O'hare. A delay leaving Michigan resulted in me having to overnight in Chicago. Such is life. It did give me the opportunity to help two Russians get to a gate in another concourse, eat at Johnny Rockets (not up to par) and try a White Castle burger for the first time (probably the last time).

It was also the first time I stepped outside the O'hare airport terminal.

Lots of good discussion from people who can competently hand prop when the situation is right...and those who had less positive outcomes.
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