Propeller and gyroscope effect

[dziki]

Hi

I'm just reading a book "Gabby a Fighter Pilot's Life" by Francis Gabreski and he a few times mention about visible gyroscope effect from the propeler during takeoff (P-40, Spit. IX, P-47). It was necessary to compensate it by rudder. I remember that in old IL2 (1946) this effect was visible.
Do You plan to built this effect into CLOD ?

dziki :salute:

[RAF74_Buzzsaw]

Hi

I'm just reading a book "Gabby a Fighter Pilot's Life" by Francis Gabreski and he a few times mention about visible gyroscope effect from the propeler during takeoff (P-40, Spit. IX, P-47). It was necessary to compensate it by rudder. I remember that in old IL2 (1946) this effect was visible.
Do You plan to built this effect into CLOD ?

dziki :salute:

Are you sure you're playing CLIFFS OF DOVER in complex engine and flight mode? ;)

Last time I took off, I had to add a lot of rudder to keep the aircraft heading straight.

[dziki]

I only fly at ATAG server (full real. set.).
I didn't noticed gyro effect at takeoff (Spit and Hurri).
Maybe because, in Spitfire, I often must hard fight with side wind and to apply a lot of aileron (without rudder). Btw, there is no problem with side wind for Hurri.
I will look at it closer at the nearest opportunity.

[Baffin]

I think it's almost impossible for a pilot to to differentiate gyroscopic precession during takeoff rotation because P-Factor, torque and slipstream are also involved as you accelerate and as you change the pitch to takeoff and rotate. In the past, any one of these terms have been used to generally describe the "Left Turning Tendency" of propeller airplanes during takeoff. I learned it as "torque", but actually it is a combination of them all that causes the instructor to yell, "Right Rudder, Lieutenant!" during flight school. Gabby Gabreski may have simply been using the term that his instructor used back at Parks Air College.

I found an outstanding description of the Left Turning Tendency here:

http://www.boldmethod.com/learn-to-fly/aerodynamics/why-you-need-right-rudder-on-takeoff-to-stay-on-centerline/

Different airplanes with different engine types also have varying magnitudes of gyro effect due to the size (mass) and the velocity of gyro rotation. Radial, rotary and fan-jets come to mind when considering the amount of metal we have in front of us, and how fast it's spinning around.

Nothing's simple... is it? :crazyeyes:

[dziki]

I've made some test of takeoffs, offline, wind 0.
Spitfire and Hurricane both have really visual tendency to turn left during takeoff, I think due to torque effect from propeller (not gyroscope as I think before).
It seems to me strange, because their propellers turns clockwise so they should to have tendency to turn right. Am I wrong ?
Also Gabby Gabreski mentions in his book, that Spitfire IX at takeoff have big tendency to turn right and it he had to compensate it with the left pedal (he mentioned also that P-40 at takeoff turns left and P-38 have no tendency to turn because engines turning in opposite direction).
So in CLOD we do have torque effect :thumbsup: , but if in a right direction ?

:salute:

[=AFJ=Oracle]

I have have found a distinct and pronounced gyroscopic effect on the Stearman. The airplane requires a prompt application of right rudder as the tail rises during the takeoff roll. The effect is very pronounced if the tail is allowed to rise quickly. The noise can easily has several degrees to the left if late in applying correction.

The Stearman was used as a trainer in WWII and was useful in getting pilots ready to solo in a P47. The ground handing characteristics of this airplane were supposed to mimic those of the much higher powered aircraft that these young pilots were training to fly.

Not sure if gyroscopic effects are modeled in CLOD. It doesn't feel that way to me based on memory. Only the Stearman has had a perceptible gyroscopic effect, and a pronounced one at that. I have not noticed it on the Super Cub or J3. My guess is that it would be most pronounced on the 109 then the Spitfire and lastly the Hurricane given the geometry of their landing gear.

[Baffin]

I have have found a distinct and pronounced gyroscopic effect on the Stearman. The airplane requires a prompt application of right rudder as the tail rises during the takeoff roll. The effect is very pronounced if the tail is allowed to rise quickly. The noise can easily has several degrees to the left if late in applying correction.

The Stearman was used as a trainer in WWII and was useful in getting pilots ready to solo in a P47. The ground handing characteristics of this airplane were supposed to mimic those of the much higher powered aircraft that these young pilots were training to fly.

Not sure if gyroscopic effects are modeled in CLOD. It doesn't feel that way to me based on memory. Only the Stearman has had a perceptible gyroscopic effect, and a pronounced one at that. I have not noticed it on the Super Cub or J3. My guess is that it would be most pronounced on the 109 then the Spitfire and lastly the Hurricane given the geometry of their landing gear.

This is an excellent example, since the rising of the tail reduces the left turn force due to reduced P-factor. In my opinion, your observation of an increase of left turn tendency during tail lift can only be explained by an overriding gyroscopic precession force.

This might be what Gabreski was referring to in the OP's book. I never even considered tail lift... :salute:

EDIT: I just came back from a Spitfire flight where I checked out tail lift and extreme pitch changes. I could not detect any gyroscopic effects but it's hard to tell on a flat screen...Torque was definitely present as the throttle came up and P-factor works as advertised.

[69th_Zeb]

Yeah didn't think of tail lift either. I got to fly a 450 Stearman (not PIC) ten years ago. My buddy is very good at it, and probably made it so I didn't notice, though I did feel the inputs to kind of gauge (he was dancing at the pedals)....okay I was more excited about the noise and smells!

If you want to get nerdier, you can ask some of the heli drivers around here about the giant fling-wing they have to deal with.

The biggest difference I see with Supercubs/Cessnas (apart from the obvious) is that they have little rotating mass. The Ham Standards on the Stearmans are heavy. I would think that tail-lift would be more pronounced for that reason.(?)

I had to do a lot of washing of different A/C types after flight and they all had their own signature oil "mess" as well. You can see how spiraling slipstream works on a particular aircraft when you wipe oil on only one side along a curve...in addition to the obvious mess on the belly. Would be interesting to observe some of that at an airshow.

-D

[Baffin]

I've made some test of takeoffs, offline, wind 0.
Spitfire and Hurricane both have really visual tendency to turn left during takeoff, I think due to torque effect from propeller (not gyroscope as I think before).
It seems to me strange, because their propellers turns clockwise so they should to have tendency to turn right. Am I wrong ?
Also Gabby Gabreski mentions in his book, that Spitfire IX at takeoff have big tendency to turn right and it he had to compensate it with the left pedal (he mentioned also that P-40 at takeoff turns left and P-38 have no tendency to turn because engines turning in opposite direction).
So in CLOD we do have torque effect :thumbsup: , but if in a right direction ?

:salute:

The link in post #4 above describes this torque effect well. ON THE GROUND, with a clockwise rotating prop (From the cockpit), the left turning tendency comes from increased downward pressure on the left tire. This increases the friction on that wheel, causing the drag on that side to increase.

Viewed from the cockpit, a clockwise rotation of the propeller imparts an opposite (Counter-clockwise) force (torque) on the rest of the airplane. Take a rubber band powered toy airplane, wind it up and release it with the nose pointed straight up... the prop spins one way and the plane rolls in the opposite direction. :lecture:

[Baffin]

Zeb,
Can you tell us about flywheels in single engine planes? It seems that there must be one if there is a self contained starter system while planes requiring "Propping" may not need one.

Flywheels must act like gyros on steroids...:flying2:

[dziki]

OK, I've learned something.
I'm glad that I was wrong about CLOD.
In fact all 3 forces from propeller at takeoff: Torque, Gyroscopic Precession and Spiraling Slipstream, when propeller rotate clockwise (from pilot view) create forces making plane turning left (but of course, if prop is turning counter-clockwise, all that 3 forces making plane turning right).
Btw, do You know any 2WW single engine fighter with counter-clockwise propeller ?

[katschmarek]

I believe most of the Russian planes. Even every-day threading is?/was in reverse (e.g bottle caps)

[=FI=Murph]

When The Merlin began to be replaced by the Griffon engine- it rotated counter- clockwise.