I'd just buy a few different props, and report back here so everyone will then know for sure!

Outcast,
I think you have incorrectly interjected some of your facts. All full scale pilots are taught that there are four factors that cause the airplane to Yaw and turn right, 1 Torque, 2 P-Factor, 3 slipstream effect, 4 gyroscopic procession. Torque is a significant factor and I believe any full scale pilot will tell you that a plane will require right rudder when giving gas, and left rudder when cutting power.

P factor has nothing to do with "Roll the wings right the fuselage yaws left”. That is caused from induced drag. The down aileron has more drag than the up aileron causing a slight tendency to pull the nose right or left just as the roll starts. (No where near as big of an affect as torque. )

I agree, I wasn't arguing that anything other tha torque causes the airframe to roll. I simply stated that some of that torque is conteracted by the slipstream, which rotates in the opposite direction. I was not attributing anything to P-factor. P-factor is not present in a hover since there is no asymetrecial force, the blades interact with the static air evenly as they rotate.

Since the original question was how to slow down a torque roll, I think it's fair to consider the forces that affect the roll rate which in a stable hover (IMO) are torque and aerodynamic resistance on the airframe

Jason

I've come to the conclusion that
I'm going to agree with somebody.
Now where's the medication?

I am a full scale pilot with over 3,000 hours, 1000 in conventional gear craft.
Torque is not one of the primary factors in the use of right rudder in aircraft, P-factor is and this is commonly misunderstood. The amount of P-factor is proportional to the props ability to absorb the engines torque. You are correct that P-factor does not roll the wing, and thats what I said in my last post. Slip stream does have a small effect on short coupled planes but not much. Gyroscopic procession has nothing at all to do with this discussion, it is the tendency for a gyroscope to drift opposite the direction of rotation over long periods of time, the reason we check the directional gyro once an hour, so unless your flying a LeRhone radial it's no concern. Induced Drag is a by-product of the generation of lift, when the aileron goes down it effectively increases the camber of the airfoil, this camber increase now produces more lift and thus more induced drag, the aileron itself is not responsible for the increase in drag.

Couple (maybe three) questions:

1) What's conventional gear got to do with it? ALL aircraft displayes left turning tendensies (right if you fly VW or speak Russian) for the same reasons.

2) It seems that the 3000 hours came over quite some period of time? If you go and read your PPL books again, P-factor might become clearer.

3) Gyroscopic procession should be in the same chapter.



Willem

See what you've started MECAM

Where's Mr. Wizard when you need him.

I think we've about covered this one. Next thing you know people will be posting their resumes to get some respect

I apologize. I've spent the afternoon dealing with some other smart***** and lost sight of the big picture for a while. I meant no disrespect to OUTCAST.

Willem

Grab 4 or 5 different size props jump in your outfit head to the field and try them all until you get the desired results. This is what I do and it really cuts down on all the confusion!!!!! you'll have to excuse me I'm from S.D. you have to show me or is that Missouri ?

Problem is, if you fly a 100cc motor, you could easily fund a complete everyday model with the money it takes to try 5 different clubs.

I do fly 100cc and 150cc Engines and if your flying different areas of the country you should have 4 to 5 different props for what ever size your flying!!! just common sense not affordabilty

Answers:
1) If you have ever flow a real taildragger you would know all about P-factor before the first 100 feet of your take off roll.
2) It did take a long time, all the way back to Vietnam.
3) I checked its not there, perhaps you could enlighten us?

Chech out this article. I found it very interesting with regard to prop performance / selection. The article is focuses on prop selection for electrics, but has some good theory about prop efficiency and performance in general:

http://members.aol.com/KMyersEFO/Fly_prop.pdf

Jason

Actually, I like this conversation, as long as it doesn't deteriorate into an argument. (willembad, & outcast have some interesting observations and obviously come from different pilot training practices and flight experience, and I'm pretty sure neither is wrong.) I really don't care to add my personal opinion but I can tell you what is on the current FAA PP written exam.

That is:
Question 3207
"The torque effect (left turning tendency) is greatest at low airspeed, high angles of attack & high power situations"
(Their words not mine)

Question 3209
"P-factor causes the airplane to yaw to the left when at a high angles of attack"
(As in tail draggers in the first 100 feet)

To answer 3208
You must know that "gyroscopic Procession is the force applied to a rotating propeller acting 90 degrees in advance of the point the force was applied"
(This is the tendency to yaw left when pitched down.)

If you look back on this thread you will see that someone did post their experience using a 2” larger prop at the same pitch and had a big increase in rotation during a torque roll. So given all this info, I would first try a smaller & lighter prop if I wanted to decrease rotation during a torque roll. It may not work but it may be the best bet without buying a bunch of props.

So Your A Pilot too. Thats neat so am I, and being in this hobby for 20 some years a person accumulates many props over the years. I was out flying today, most of the afternoon anyway until dark,the way it looks you were busy looking up Faa PP exam questions to post. I think I had more fun than you did.I went out and tried all these concepts in real life test flights.

Disclaimer: I didn't read page 2, so I am not sure if I will repeat what's already said.

******************************

According to some thrust calculator out there, static thrust is not affected by prop pitch. (I am not sure if I agree). But let's say we assume that static thrust is not reduced by lowering pitch, then 18x8 and 18x6 will hover the same plane at the same rpm, say 5000. But we know that 18x8 @ 5000 corresponds to a higher throttle setting than 18x6 @ 5000, so the throttle stick for hovering will be lower for 18x6. Now, TR. We've previously established that for same diameter and same rpm, a higher pitch will have more torque. So, 18x8 @ 5000 will generate more torque than 18x6 @ 5000, if both are hovering. Therefore, 18x6 will torque roll slower due to lower torque at hovering rpm.

Sounds good Jerrysu31. You lucky bum, I didn't even get home from work until after dark.
Your real life test flight findings are...............?
Come on don't keep us waiting, what props produced less (or more) torque roll speed?

When it comes to a torque roll... I don't see these gyroscopic forces or P forces having any effect. It's the engine turning the plane and the prop... rather than just the prop as would be the case in normal flight. No?

When it comes to a torque roll... I don't see these gyroscopic forces or P forces having any effect. It's the engine turning the plane and the prop... rather than just the prop as would be the case in normal flight. No?

When it comes to a torque roll... I don't see these gyroscopic forces or P forces having any effect. It's the engine turning the plane and the prop... rather than just the prop as would be the case in normal flight. No?

When it comes to a torque roll... I don't see these gyroscopic forces or P forces having any effect. It's the engine turning the plane and the prop... rather than just the prop as would be the case in normal flight. No?

... somebody slap me, I'm skipping...

I went out with my GP Extra 300s Power OS BGX-1 the first prop I used is the one I hover it with APC 18x6W not much for torq roll the next prop I used was the APC 18x8W makes it easier to torque roll (torque speed faster) Than I used a Zinger wood (lighter) 18X10 almost the same as the APC 18X6W then I used a Zinger 18X6 wouldn't torque at all but rpm real high then I used a Zinger 20X8 torque roll very slow fell right in between the APC 18X6W and the 18X8W (for what its worth) this is what I came up with and had an enjoyable day in S.D. for a Dec. afternoon wind 5 to 10 42 degrees a little chilly standing still though. Carhart Coveralls is the key word for today. and those funny gloves with no finger tips. Happy Flying!!!

Having read all of the above posts-- I really did not see any comments addressing a question I have.
" If the given model hovers and holds stationary--then the amount of energy being used to hold and hover is the same "
Right?
If the engine rpm is changed -yet the hover is still the same -- the energy required is still the same.
Right?
If the rpm remains the same - on different type props -what is going on?
Looks like prop efficiency has a huge roll here -
"torque " applied by the engine - does not look to be relevant.
So - we have a "constant" of the net power required to hold altitude - regardless of torque or rpm involved.
The variables left are :
A rolling hover -or a stationary hover -- which requires more energy to accomplish?
The obvious answer would be the rolling hover - --as it took some energy from somewhere - to start an additional motion.
Here is what I thingk ( not certain) is happening.
To roll and hover -- the prop must "slip " more -- that is absorb more power -yet not add more lifting force.
More blade angle -yet less thrust is required. ( for hover AND roll)
The heli setups demonstrate this the best - in my book.
Did I get it right?

Right on the button Dick! The torque absorbed by the propeller controls the roll speed. :thumbup:

This thread looks like the old conundrum ..

Take a large truck with an enclosed box body. Place a heavy model helicopter on the deck of the truck with the doors closed.

Weigh the truck.

Now start the engine of the helicopter and hover inside the enclosed truck body.

Will the truck be lighter by the weight of the helicopter?

(argh!)

David C.

use a turbine they don't produce any torque!

*deleted*

OK then, if the truck had a flat bed (i.e. wasn' enclosed) wouldn't it be lighter by the weight of the helicopter, if it took off?

The question is, at what stage in the 'openness' of the truck body does the weight of the helicopter not any more impart it's weight on the truck?

Or, to put it another way, if the hovering helicopter is still weighing down the truck with the enclosed body (as you suggested), is it the movement of the air that is doing it, as there is no other contact with the truck if its hovering.

Its a bit like standing in a bucket and lifting yourself off the ground with the handle!

David C.