How Much Pull

[Harleyman]

Occasionally when an interested spectator walks over to talk in-between flights, I’ll be asked: “How much does that airplane pull on the lines?”  I always say something like: “it has a pretty good pull”, not really knowing.  I’ve guessed at about ten, maybe fifteen pounds.

Anybody know, how much force a .35-.40 size stunter pulls in level flight?  Just some average, ballpark numbers, even assuming a Ringmaster/Fox 35.

Ten pounds?  Twenty?

[RC Storick]

    Tell them around a hundred pounds!  

[frank carlisle]

Chris,
I don't know how to do the arithmetic but I'm sure someone here does. I recently had someone calculate the pull of a 75 oz. plane on 70 foot lines going about 51 mph.
The answer was 12-15 pounds. I'm guessing a ringmaster at a similar velocity on about 56 foot lines would yield about 6 pounds of pull. Dead wind conditions.

Here is a good answer for casual observers when they ask that question.........

Well the model weighs about 2 pounds and is traveling at about 83 miles an hour the lines are 56 feet long and these conditions create a g-load of about 25 gravities. So............the pull on the lines is about 300 pounds.

If they ask if you ever get dizzy tell them no, I am physically fit.

[john e. holliday]

Now fellows I have seen and heard all kinds of stories about how hard a plane pulls in level flight.  As an experiment, take a 10 pound bag of flower, sand or whatever and fasten a handle to it somehow.  Now lean over and pull up on the handle.  Now think about when you do a pull test with plane, lines and handle.  In fact take the pull test scales and hook the handle to it and pull until it feels like it does when you are flying.  You will find out that plane is not pulling nearly as hard as you thought.  Later,  DOC Holliday

[Harleyman]

    Tell them around a hundred pounds!  

I think I'll use that one.

[frank carlisle]

Chris,
Spreading the manure is the way to go. Spread it thick and smooth. Spectators need a cool story to take home.

[Alan Hahn]

Somewhere I posted the pull in "g's" as equal to

pull(in 'g's)= 1.23*linelength/(lap time^2).   ( ^2 means to square the lap time)

Lap time is in seconds, line length in feet.

Anyway, for 5 second laps, and 60 foot lines, the pull (in 'g's) is ~3 'g'.

For a 40 oz  2 1/2 lb) plane, this comes out to be ~7.5 lbs.

This is the centripetal force you need to pullon the handle to keep the plane moving in a circle. Any outboard thrust from the engine or outboard rudder trim will increase the force.

So a guess of 10 lbs isn't that far off. A light Ringmaster (~30oz) would be about 5 lbs.

[Steve Helmick]

I don't think that's a good idea. Anybody with any common sense would think that 100 lbs pull on those itty bitty wires would be VERY dangerous. And they'd be right. If you want to keep your flying field, don't spread the manure.

"Well, the pulltest required for this model is 40 lbs, and that's a safety factor of at least 5, maybe even ten. The pull isn't a big deal for an adult of average size and muscle tone."

That said, I did an interesting experiment with my 4th-hand "Lancer" (I think it may have been of SV-11 lineage...68 oz) with Double Star .60bb. I liked the solid line tension, but I'm 6'2", around 220 lbs. Randy P. and Bob Smiley came to Arlington that day, and it was a tad breezy around mid-afternoon. I put Bob up for a test fly on this critter, and it looked like about all he wanted, but he was grinning, after the landing! Bob's 5'4" and maybe 130? It's not all about weight. My height works against me, unless the lines go slack, then the long arms might help. A little. Not very often.   Steve

[Greg Hart]

Here is the best laymen answer. Put your hand out and grip their hand. Then give a pull on their hand and say somewhere about here. This isn't rocket sceince, Give them a feel, they will understand that.

[Jim Pollock]

The average pull is between 8 and 12 pounds in level flight.  It's something line 1.5 to 2.5 pounds when the aircraft is overhead.

The pull actually needed is enough to avoid the Netzband wall!

The wall is lack of enough pull to enable the control system to work.

Jim Pollock   

[Harleyman]

The clown in me still likes the heavy manure reply