GScholz more ont turbo props:

[Golfer]

I've gone out of my way to pull a lot of back issues of Flying (I've only subscribed since July 2001) and I believe it was a 210 that mashed up his airplane while he was holding short.

That would be great if you could get some insight.

HoHun---the point is it doesn't matter how much torque there is.  Double, Triple, Quadruple, Infin-it-oople  It won't cause any effects to the flight characteristics of the conventional multiengine airplane with engines on the wings.

[HoHun]

Hi Golfer,

>HoHun---the point is it doesn't matter how much torque there is.  Double, Triple, Quadruple, Infin-it-oople  It won't cause any effects to the flight characteristics of the conventional multiengine airplane with engines on the wings.

Hm, not sure what you mean by "no effects on the flight characteristics", but it sure creates a rolling moment the pilot has to arrest somehow.

Engine torque that does not cause a rolling moment is transferred to Westminster Abbey instead, making Newton spin in his grave ;-)

Regards,

Henning (HoHun)

[Golfer]

based on what you said, the drag of the spinning props takes care of the engine torque.

With regards to multiengine airplanes only...ONLY.  Thats all I've ever been referring to, torque doesn't do anything to the airplane.  For the 35th time, without the engine on the longitudnal axis going through the CG, there just isn't any way that engine torque alone can cause a rolling tendency in the airplane.  It will not happen.  ever.

[hitech]

Golfer: Look at my diagram again in detail. You should see how torque in a multie engine plane  is transfered to a rolling moment about the CG.

And the article you post completly supports what I have been saying. Just as there would be different wieght on the wheels on the ground. Somthing in the air will have to compensate for the difference in the force on  wheels when flying.


HiTech

[hitech]

Straiga: When you have a heavy wing do to fuel. How do you correct for it?

HiTech

[Golfer]

The middle paragraph relates to the definition of torque.  We all understand what it is.  It also is talking about a SINGLE ENGINE aircraft.  Torque is a factor due to th fact the engine is mounted in the middle of the airplane and the torque twists right along the longitudnal axis going through the CG.  This gives it the leverage it needs to cause the airplane to roll.  The column also goes on to conclude that torque is innocent, provide yourself with a copy of the magazine if you need further detail.  Feb 2005 issue.


In a traditional twin, Torque doesn't to anything to roll the airplane.  Nada.  Zip.  Zero.

[Straiga]

And the article you post completly supports what I have been saying. Just as there would be different wieght on the wheels on the ground. Somthing in the air will have to compensate for the difference in the force on wheels when flying.

This is referring to a single engine not a multi-engine.

Golfer: Look at my diagram again in detail. You should see how torque in a multie engine plane is transfered to a rolling moment about the CG.

I do not see this at all if anything its show two indipentent wings wanting to roll left but cant because of the fuselage with elevators and rudder attached. I see lots of YAW though.

Straiga: When you have a heavy wing do to fuel. How do you correct for it?

By fuel transfer or a little bit of rudder trim. If it is a large inbalance a little bit of rudder and airleron trim just a little. I know were your coming from, a large wieght in the wing has a roll moment but it is not that great at all. I have had 5000 LBS fuel inbalance in a DC-10 with out using trim. We found out the other day that one of the King Air 200s had the left AUX tank full of gas but we did not know it because of an inop fuel transfer system that was 637 Lbs of fuel we had no idea it was there or did we have to use anykind of trim either.

Multi-engines still YAW.

Thanks again Golfer

Straiga

[hitech]

Ok I give, newton was incorect and forces do not require a = and oposit reaction.

Btw to put the engine torque into a scale I can relate to and to know what it feels like.

My RV is 200 HP at 2700 rpm. So that equates to 390 ft/lb torque.

If a fuel tank is 5 gallons less than the other it would create between 100 to 200 ft/lb of torque.  Didn't actualy messure the moment arm of the tanks.

Now in reality the fuel isn't creating a torque, but wrather moving the CG lmoving left or right, And the lift being greater on one side or other of the CG is creating the torque. For this example It dosn't make any difference.

I.E. It is hardly notisable.

And I rest my case why pilots are not always the best at describing all the forces involved in making a plane fly.

HiTech

[Golfer]

And I rest my case why pilots are not always the best at describing all the forces involved in making a plane fly.

I've taken and scored well (B or better) in 3 different (2 advanced) aerodynamics courses.

Not to mention have flown all 3 basic types of twin engine airplanes.  Conventional, ex. PA-23.  Counter-Rotating, ex. BE-76.  Centerline Thrust, ex. C-337.

I know what controls I use to do what with the airplane.  With two engines operating in normal conditions on traditional twins with the engines on the wings...aileron trim isn't one of them.

That's a simple fact.  Wouldn't you agree if no trim is necessary, then there isn't a force being generated that needs to be countered?  If there was something there, holding in a control pressure for the entire flight would be fatiguing, uncomfortable not to mention annoying.

Hitech, you're right when it comes to single engine aerodynamics, torque is a factor.  NOT in multis that are non-centerline thrust.

[hitech]

Straiga:

What plane. The ones I tested all show the speed of the CV. Unless you were facing backwards?


HiTech

[hitech]

Golfer: Just because you are not triming for the force, does not meen that it hasn't already been riged into the air plane.

Btw care to make a wager on my claim that torque is the same on multi Vs not? In fact Im willing to wager HTC on it.

And can even give you a simple experiment you can do at home to find out.


HiTech

[Waffle]

Wouldn't take that bet......

What would you do if you had Pyro, Skuzzy and everyone else sitting around your house all day?

[HoHun]

Hi Straiga,

>Multi-engines still YAW.

Yes, but it's not torque that causes the yaw.

The engine torque causes a roll moment.

The pilot causes the yaw moment :-)

This is in fact only a matter of perception. You're looking at the entire system and considering the bottom line. Hitech as an engineer considers all the individual sums, and it seems to me he arrives at the same bottom line, just a bit slower - and while accounting for everything :-)

Regards,

Henning (HoHun)

[HoHun]

Hi Golfer,

>based on what you said, the drag of the spinning props takes care of the engine torque.

Not at all. The drag of the spinning propeller IS the engine torque.

Drag is air pushing against the propeller against its direction of travel. That force is transferred directly to the engine mount, where it's actually measured on some aircraft, as BMEP with the big radials of old or as, well, torque on turbines. Something has to oppose this torque, or the aircraft will be spinning like a top in no time at all.

And whatever it is that opposes torque, it has to do so in the form of a rolling moment because by definition, everything else is not opposition.

Regards,

Henning (HoHun)

[Golfer]

The amount of torque being exerted on a twin is actually double.  You've got two engines producing torque.

I.E. a Baron has 2x the torque of a Bonanza.

The effects torque has on the airplane in flight are different.

While the rotating propeller, engine torque, p factor and whatever else in a single require holding of right rudder (gasp!  a correction for yaw) in a twin things are different.

Use a Beech Duchess as an example, counter rotating props.

No rudder necessary for takeoff/climbout flying a constant heading.  Nada.  Zip.  Zilch.  None.  Zero.

In a Piper Apache, thanks to the spiraling slipstream and propeller side force you may need to hold some right rudder, just like a single.  This is not due to engine torque, rather I will cite Peter Garrison again "The cylindrical slipstreams of a twin's propellers pass on either side of the vertical fin..."
"If it doesn't [have counter-rotating props], as many do, then a low horizontal stabilizer tends to concentrate the momentum of the descending side of the left engine's slipstream on the left side of the fin while shielding the fin from the ascending side of the right engine's slipstream; the result is a left yaw, just as in a single."

The reason torque isn't having an effect is because with the weight of the airplane, air passing over it or just 'because' there is no leverage for the torque to cause the airplane to roll.  This is because the torque does not have the same advantage as a single (rotating around the CG) instead the entire torque and rotation of the propeller is outside the long axis of the CG.

The 160hp engines of the Apache may as well be Cox engines if you're trying to get the airplane to roll due to engine torque.