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Hand propping a PPonk 470-50

J

JohnnyR

SPONSOR
AK, ME - what time of year is it?
Can an operator [relatively] easily hand prop a PPonk 470-50 , AKA O-520 with 7.5:1 pistons? Bear with me, as I imagine some readers might consider this a crazy question.

As I'm at around 1,500 hours on my 470R, I've begun to plan for the next engine. I believe it's going to be a PPonk done with a 520 case and 7.5 pistons (lower compression). I have had to hand prop big engines before to keep from spending the night in the boonies, so expect the same could happen in the future.

I don't know what the piston compression is on the 9-cylinder P&W R-985 on a Beaver, but I've hand propped those numerous times without crazy amounts of difficulty. So, how about the PPonk?

Thanks,
Johnny
 
I have a friend that can start his by hand-propping anytime he needs to. He has a certain process, knows exactly which blade it will fire on every time.
 
R-985 is supercharged, so low compression = easy to prop.

That said a P Ponked 470 should be a piece of cake.

MTV
 
mvivion said:
R-985 is supercharged, so low compression = easy to prop.

That said a P Ponked 470 should be a piece of cake.

MTV
Click to expand...

Remember to grab a blade at around 7:00 o clock on a TW airplane and walk your self to the right. If you grab a blade above 9:00 o clock you risk the blade hitting your legs at the bottom of the ark.

Glenn
 
With these small Lithium jump packs the only reason to hand prop is starter failure.
 
My brother hand propped his 180 all the time, winter, when he lived in Kotz. Shouldn’t be a problem.


Sent from my iPhone using SuperCub.Org
 
The only time my Pponk hasn't started was from frosted plugs or battery exhaustion after inadequate pre heat. Hand propping won't fix that. I have no doubt I could start it in good conditions, but I carry a Jump Pack in my day pack so I won't need to.
 
G44 said:
R-985 is 7 to 1 compression if I remember correctly.
Click to expand...
Along with a lot more reciprocating mass. They wake up pretty slowly. The only round motor I ever propped was a 1340 and it was quite an experience. As I passed over the top of compression there was the impulse click and then the prop just sort of accelerated out of my hand in slow(ish) motion.
 
PerryB said:
Along with a lot more reciprocating mass. They wake up pretty slowly. The only round motor I ever propped was a 1340 and it was quite an experience. As I passed over the top of compression there was the impulse click and then the prop just sort of accelerated out of my hand in slow(ish) motion.
Click to expand...


Alot of engines with mags start much better at a slow rotation speed then fast like a starter spins it. That why some finally kick off when you take your finger off of the starter buttom.

Glenn
 
cubdriver2 said:
Alot of engines with mags start much better at a slow rotation speed then fast like a starter spins it. That why some finally kick off when you take your finger off of the starter buttom.

Glenn
Click to expand...

I thought that was cause you weren't robbing battery juice going to the coil for the starter 8)
 
PerryB said:
Along with a lot more reciprocating mass. They wake up pretty slowly. The only round motor I ever propped was a 1340 and it was quite an experience. As I passed over the top of compression there was the impulse click and then the prop just sort of accelerated out of my hand in slow(ish) motion.
Click to expand...

985 and 1340 doesn't have an impulse coupling.
John
 
Maybe I imagined remembering the click. I've been playing with little motors too long. The 1340 prop job was 35 years ago.
 
About 40 yrs ago, my Dad hand propped his 1340 on his Thrush spray plane and the prop bit him. I had taken the water truck to another airport and waited and waited. Finally he showed up with his left hand bandaged up. The doctor stitched him up and he was good enough the spray. Never did find his wrist watch. He was about 55 yrs old and i don't think he tried that again.
 
Did I mention the Beaver was on straight floats? It always seems safer to pull it when behind the prop, but I'm sure folks have messed up there as well...
 
Should not be a big deal at all.

Just did the O-540 on my Maule, one blade and she took right off.

Fuel injected can be a little less fun.
 
I've never seen a Beaver hand started. That couldn't be fun on a chilly morning first flight. I have watched a pilot prop a 206 on floats. That didn't turn out well. For a pilot to solo prop a 206 means from the right float. Getting to the controls took longer than it took for the plane to run into the brushy bank.
 
If it’s possible,I certainly prefer propping from behind. In floatplanes, that’s mandatory unless you have some pretty amazing skills.

MTV
 
I have been unable to get the 3 blade p-ponk to hand prop, I did not have trouble with the 2 - blade 470J, but it has more to do with the prop than anything I suspect.

sj
 
Agreed. I have never nor likely would ever try hand propping on floats from the front. To clarify, I was trying to convey that I’ve always felt safer swinging the prop from behind, if conditions allow.
mvivion said:
If it’s possible,I certainly prefer propping from behind. In floatplanes, that’s mandatory unless you have some pretty amazing skills.

MTV
Click to expand...
 
Last edited:
SJ said:
I have been unable to get the 3 blade p-ponk to hand prop, I did not have trouble with the 2 - blade 470J, but it has more to do with the prop than anything I suspect.

sj
Click to expand...

Hmmm.... interesting.
I would likely put the 3-blade MT on the PPonk engine. If I recall correctly, the blades are the same length in the two blade and the three blade units. If so, should “feel” similar on the swing.
 
stewartb said:
I've never seen a Beaver hand started. That couldn't be fun on a chilly morning first flight. I have watched a pilot prop a 206 on floats. That didn't turn out well. For a pilot to solo prop a 206 means from the right float. Getting to the controls took longer than it took for the plane to run into the brushy bank.
Click to expand...

It comes down to setting the controls up first so that the plane is sorta going where you want it to after you start it. I do it 10 times a day sometimes (not in a Beaver or 206 but a J4) in some tight spots. Judge the wind and set the rudders for where you want it to go. If you try to rush getting in it takes twice as long. Get back behind the strut and before you start to get in look and see if its going where you want it, if not you have a few choices. Reach in with your hand and adjust the rudders on the right side, or throttle, or shut the mags off if its not listening to you. Then slowly get in. Sometimes you just gota paddle your way clear of hazards.

Glenn
 
SJ said:
I have been unable to get the 3 blade p-ponk to hand prop, I did not have trouble with the 2 - blade 470J, but it has more to do with the prop than anything I suspect.

sj
Click to expand...
Was the 2 blade an MT...? Or a Metal prop..?

I hear a wood composite doesn’t have the mass or momentum to be hand propped. Don’t know. Just hearsay.....

I’d like to know if some have been able to prop a 180 with a PPonk, with an MT.

3 blades are much more challenging.
 
Here is the Beaver video: https://www.facebook.com/FrostlineProductions/videos/1420879544688810/

As far as running a 206 into the brush hand propping, I preach to tie the plane down! One line from a cleat to the beach would save a lot of grief. One line from the tailwheel to something saves lots of teeth gnashing.

I know some get away with it for years, but one thing to consider is that if you do it all the time you are much more familiar with how she will react and fire. If you start it once every 5 years by hand you are probably clueless as to exactly where that throttle must be to fire the engine, and a little extra is bad news.

If I am in a no starter plane, I park with a tail tie in mind. I also carry one long line to get to something that is 40 ' back.
 
SJ said:
It's not compression, it is more the physics of the 3 blade vs 2 blade.
Click to expand...

Physics or just plain shorter? Or the head game of you thinking that the blades are closer and the chance of getting wacked is greater? Six cylinder is tougher because the compression stroke feels shorter then a 4 cylinder that most are used to, and they tend not to follow thru with the full stroke because the next cylinder coming on line is changing what you feel.

Glenn
 
I would rather prop a 3 blade 6 cylinder Continental than a 2 blade

A 3 blade Continental always has a blade at the right location at firing.

A 2 blade does not. And you have to find the cylinder that fires where yu can throw the prop.

R985's are childs play to hand prop. Big heavy props and low compression and big magnetos that dont need impulse couplings.

I ve never been around the boosted mags on 985's in 30 years of Beaver work. Wworth talking about? I could ask some old timers around.

I prefer to prop from behind. Floats or wheels.

a 206 or Bananza is no fun. Floats or not.

A light prop like an MT probably doesnt make it easier. Anyone??
 
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