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Hand propping RV's

R

RScott

Well Known Member
Our EAA chapter had a good hand propping session last night, & everybody who wanted to had a chance to try hand propping, with proper instruction & supervision so it wouldn't be a hand chopping session.

But we only addressed propping planes like Cubs & today I got to thinking about folks with 3 blade props and folks with electronic ignitions, common on RV's. Tricycle gear makes things even more challenging.

On most planes set up to start by hand propping, the prop is indexed so the impulse mag fires when the prop is in about the 7 o'clock position. Where is the blade when you hear the mag snap with a 3 blade prop?

Can you hand prop any of the electronic ignition systems?

FWIW, if you have one mag, it should be on the left side and should have an impulse coupler.
 
Been hand propping all kinds of airplanes for all of my aviation career since the mid 60s. Even propped my RV-6 several times.

However with my current 9.5:1 compression and 3-bladed prop....NO WAY!

Most electronic ignition systems will not fire at "hand propping" speeds.
 
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If you have the prop indexed to be in the 10-11 o'clock position for a 3-blader, it will only be in that position on every alternate compression. So you may need to reposition it over the next compression (with mags off) if it doesn't start on the first swing. You should always move a prop blade on the assumption that the engine will start even when you have the mags off!

If the battery is flat, then electronic ignition will probably not work. P-Mag state that you can use a PP3 to energise the electronics sufficient for hand starting. A battery that's too cold and feeble for cranking could still be sufficient to drive the electronic system. If you're completely flat, you probably won't have enough field current to bring the alternator on line either.

Hand propping electronic ignition because you don't have a self-starter shouldn't be a problem as they usually retard to TDC for starting.
 
Hand Propping

I learned to hand prop a Cub as a 15 year old a long, long time ago. I have the utmost respect for hand propping. I have been hit on the hands two times, both times the switch was off. One of these times I was pulling the prop backward with the switch off and it fired and turned one blade.
Having said that I have hand propped several 10-1 Lycomings with three blade props. It is an ordeal on a hot start. I have hand propped the Navaho Chieftain at least three times when starter failed. The start switch must be placed in the start position each time the blade is pulled to get shower of sparks. Every other blade the switch is turned off to reposition the prop. 450 Stearman or Twin Beech is incredibly easy, even with three blade, because the compression is so low. For electronic ignition in most cases you just need minimum battery voltage for the system, some of them will run on quite low voltage.
 
JRS.... just to thread hijack a bit. Battery was dead in a remote part of Alaska one day in the Beaver. Wondered if my time hand propping the Luscombe would do me any good. Called on the lake cabin HF to the boss. He said... just walk out to the front of the right hand float. Swing the prop from the rear. (one arm holding the strut) You are quite correct.... that 450 horse Pratt engine started easier than my RV !!!
To the original poster... might be better to get some juice to the battery. And have a spare starter in inventory. Cheaper than prosthetics.
 
Mel said:
...
However with my current 9.5:1 compression and 3-bladed prop....NO WAY! ...
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I agree with Mel, no way would I hand prop a 3-bladed prop, regardless of the compression ratio.

Mel said:
...Most electronic ignition systems will not fire at "hand propping" speeds.
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P-mags will fire at hand prop speeds. You can power one P-mag with a 9 volt battery and hand prop it and it will light off very easily.
 
I grew up hand propping Cubs - have done the RV-6 just once when the starter casting fractured and left the starter hanging by the cable at an out of the way place. Two blade prop, but still very awkward. Would rather not do that again unless I am being chased by savages with blow guns.......
 
I'm pretty comfortable with it and have done it routinely with my RV-6 2 blade while waiting for a new starter. I would not try it with a 3 blade. I have also routinely done it with a flying club C172 that didn't have a lot of spare money for parts. I didn't like that so much.

Tom Navar talks about unsuccessfully trying to hand prop a DC-3. Couldn't make it work. A good mule was the key there.
 
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Ironflight said:
I grew up hand propping Cubs - have done the RV-6 just once when the starter casting fractured and left the starter hanging by the cable at an out of the way place. Two blade prop, but still very awkward. Would rather not do that again unless I am being chased by savages with blow guns.......
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You should have paid attention in Hovitos class.
 
RScott said:
Our EAA chapter had a good hand propping session last night, & everybody who wanted to had a chance to try hand propping, with proper instruction & supervision so it wouldn't be a hand chopping session.

But we only addressed propping planes like Cubs & today I got to thinking about folks with 3 blade props and folks with electronic ignitions, common on RV's. Tricycle gear makes things even more challenging.

On most planes set up to start by hand propping, the prop is indexed so the impulse mag fires when the prop is in about the 7 o'clock position. Where is the blade when you hear the mag snap with a 3 blade prop?

Can you hand prop any of the electronic ignition systems?

FWIW, if you have one mag, it should be on the left side and should have an impulse coupler.
Click to expand...

Good way for anyone to have a heart attack if they don't trip and get hit by a blade. OK with low compression engines, I guess, but who has one of those these days and who is spun up to do it safely? Almost no one. I had an uncle who could do it standing on a float in the water hanging on where he could for when it came to life and then quickly find his way to the front seat while I was sitting useless in the back seat and the airplane was moving.

If the starter doesn't work, I don't fly or ask anyone to hand prop. The 0360 can be a bear to get running, I did it years ago with the tail tied down but that was when I was desperate to fly or the old Cherokee needed battery charged. It was dicey getting the tail untied while the engine was running. :)
 
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Lightspeed ignition can also be hand-propped. The 'wasted-spark' system fires the plug anytime the magnets in the flywheel pass the sensor, regardless of speed. Not sure about the Hall-effect system, though.

Regarding that crop-duster video, I'd worry about prop damage. Was that a hook on the end of that cable/rope and was it looped over a blade? :eek:
 
Prop

I think the DC3 was done with a rope. I remember Paul writing about it sometime later.
I flew my Pitts 1000 hours in 11 years. Never had a starter. Most of the time I was by myself. Giant, heavy wood chocks, tied the tail, glider hook on the tail.
The three blade really isn't any different except for the issue of switch off every other blade.
 
Think long and hard as to whether you really NEED to start an airplane with a dead battery or starter. If you decide you do NEED to get the airplane started, think long and hard about how you're going to SECURE it. The owner of the Cherokee that ran through my 170 last summer did neither:
1405823177000-5.jpg
 
jrs14855 said:
The three blade really isn't any different except for the issue of switch off every other blade.
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Though I'd mention that a 3-blade prop means a light wood/composite prop unless you're running a 6-cylinder 540 (Rocket/RV-10). Propping a Lyc. 180 HP motor with a metal prop is not very hard, given how much prop inertia helps. But after switching to the light 3-blade Catto, it is now hard enough that I will not do it.
 
Three blade

Some of the three blades I propped were MT or Hoffman. Constant speed with wood/composite blades is probably about half way between a metal fixed pitch and a wood/composite three blade fixed pitch. One of the harmonic dampners would add some flywheel effect to a fixed pitch wood/composite.
Catto two blade on a 180 Pitts was never a problem, just a bit different technique to make up for the lack of flywheel effect after it fires.
 
longranger said:
Think long and hard as to whether you really NEED to start an airplane with a dead battery or starter. If you decide you do NEED to get the airplane started, think long and hard about how you're going to SECURE it. The owner of the Cherokee that ran through my 170 last summer did neither:
1405823177000-5.jpg
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Wow, that is terrible. What angle did it hit from? Looks like the Cherokee backed up and ran over it a couple times!
 
It Comes Down to What Is An Acceptable Level of Risk

The comments so far all seem to have merit. I understand those that have said that the engines in our RV's are "too much" for varying reasons. If a person feels that way, then they should never give in to "gotta go-itis".
I had to hand prop my RV (O-360) on my very first flight after I bought it (Had to sit in it and make airplane noise the night before, and left the master switch on:mad:) Like the gentleman who commented that he had been flying Pitts without electrical systems, I too have been around some planes with larger engines that needed to be hand propped. In the airlines, we had an "Abnormal Checklist", and if you are hand propping your O-320, O-360, or O-540, you better have a procedure that includes more than "mags hot"!
The previous posts contained some very valuable suggestions to keep your day from becoming a bad one. If you ever feel that you might be inclined to prop your plane, get trained by a qualified individual. When the time comes, it should not be your first time, and if it scares you bad enough that you are trembling...Put the canopy cover back on and call it a day!
 
not worth it!!

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!!
 
Some days are good, some not so good....

There was a sad incident locally a few years back, the pilot tied to his Luscombe to his nice F-150 truck for hand prop job.

The engine started, aircraft lurched forward, broke the rope and the pilot grabbed a strut to try to stop the airplane but only caused it to turn 180° and plow into the nice F-150 truck.

Airplane damaged pretty much, F-150 same. It was not a good day.....:)
 
David-aviator said:
There was a sad incident locally a few years back, the pilot tied to his Luscombe to his nice F-150 truck for hand prop job.

The engine started, aircraft lurched forward, broke the rope and the pilot grabbed a strut to try to stop the airplane but only caused it to turn 180? and plow into the nice F-150 truck.

Airplane damaged pretty much, F-150 same. It was not a good day.....:)
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That's why you make sure the throttle is closed or just cracked a little bit when hand propping.
 
Prop me up

N941WR said:
That's why you make sure the throttle is closed or just cracked a little bit when hand propping.
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Amen brother!
I've propped the X many times with a 2 blade Catto, 180HP with 8.5 compression and P-Mags. Also propped my IO540 Rocket a few times. It's not the primary method for getting the engine going but good practice if you ever have to get home from the boonies.

ROE: Tie the tail down, use chocks, throttle slightly cracked, area clear except you. Pull prop through 8 blades with the switch off. Pull through and step away each time whether it fires or not. Ya never know...

PPPPPP rule applies...
V/R
Smokey
 
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smokyray said:
Amen brother!
I've propped the X many times with a 2 blade Catto, 180HP with 8.5 compression and P-Mags. Also propped my IO540 Rocket a few times. It's not the primary method for getting the engine going but good practice if you ever have to get home from the boonies.

ROE: Tie the tail down, use chocks, throttle slightly cracked, area clear except you. Pull prop through 8 blades with the switch off. Pull through and step away each time whether it fires or not. Ya never know...

PPPPPP rule applies...
V/R
Smokey
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And make sure you are propping it on the impulse mag only!
 
Ironflight said:
Would rather not do that again unless I am being chased by savages with blow guns.......
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I agree with Paul. There would need to be an extremely compelling reason for me to hand prop an RV.

I am tall so unlike most of the other aircraft I have propped an RV spinner is pretty low. That makes for some less than ideal body mechanics to perform the task in my case. Like Mel, I would not do a high compression three blade engine period.

Would it work? With plain old magnetos, Yes.
Could I pull it off? Most likely.
Is it worth the risk? Probably not, but that is just my opinion about my personal situation.
 
Jumper cables also work. Safer to be working behind the prop than in front. I can get at the positive battery terminal through the oil door, and ground on the engine. I had a helper do this for me when I had an alternator failure and was away from my home airport. Battery was sufficient for a 20-minute flight home but not enough to crank the starter.
 
Propping

There are a huge variety of emergency batteries available that would start the airplane if the battery is the issue. The Piper external power plug would be the best option, if your oil door is large enough it could be tied to a lanyard inside the oil door for emergency use only.
If the starter is the issue and the choices are sitting for a few days waiting for a new starter, I am going to hand prop.
My own rope or better yet a quality cargo strap.
Large chocks.
Turn off the fuel-if the throttle is too far open the engine will quit before the airplane moves very far. If the throttle is at or near idle, there is plenty of time to turn the fuel back on.
While it is standard protocol to hand prop on impulse mag only, there is very little chance of the non impulse mag firing at hand propping r/m. With a combination mag/start switch the non impulse mag starts firing as soon as the switch is released from the start position.
 
jrs14855 said:
..Turn off the fuel-if the throttle is too far open the engine will quit before the airplane moves very far...
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Next time you start your engine, start taxiing with the fuel shut off. On my carb'ed engine, I was surprised at how far I could taxi before it died. (Just one of the tests I performed in my Phase 1.)
 
Sam Buchanan said:
And make sure you are propping it on the impulse mag only!
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jrs14855 said:
While it is standard protocol to hand prop on impulse mag only, there is very little chance of the non impulse mag firing at hand propping r/m. With a combination mag/start switch the non impulse mag starts firing as soon as the switch is released from the start position.
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The one time I hand-propped an RV-6A with O-360 the prop was kicking back with the key switch on "Both". After it occurred to me to have the pilot put the switch on "Left" it started smoothly on the first blade.
 
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