GScholz more ont turbo props:

[hitech]

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

Off course counter rotating props cancle eachother out with torque, but that isn't the question at hand. Why do you think they make them counter rotating?

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.

Everything you stated is correct with the exception of this quote.

It realy  dosn't work like you think it does. Moving them off CG has absoltly no effect to the roll moment i.e. torque of the airplane.

HiTech

[Straiga]

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.

You can keep HTC its not much to me plus my retirement is already paid for. But I bet you will not go get some multi-engine time, you will see the light.

It realy dosn't work like you think it does. Moving them off CG has absoltly no effect to the roll moment i.e. torque of the airplane.

I beg to differ.

Off course counter rotating props cancle eachother out with torque, but that isn't the question at hand. Why do you think they make them counter rotating?

To not have a critical engine thats why. If you had any multi-engine experience you would know that.

Straiga

[HoHun]

Hi Golfer,

>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.

Due to Newton's axioms, the torque-induced roll moment and the opposing roll moment have just the same in a (conventional) twin-engined aircraft as in a single-engined aircraft.

However, I'm ready to believe that due to the different layout the effects on piloting technique are very small or even unnoticable.

You have pointed out that torque is not the only effect, so it might simply be hidden by other, stronger effects. Add the radically higher rotational inertia of a twin and consider that a pilot perceives the forces disturbing the equilibrium, but not the forces in equilibrium, and I'm only mildly suprised there is no perception of this rolling moment and that it is irrelevant for piloting technique as a result.

That's not the same as as saying the rolling moment does not exist, though :-)

Regards,

Henning (HoHun)

[Holden McGroin]

What happens in a three engine plane if all the motors are counter-rotating?

is the torque counter-balanced?

[hitech]

To not have a critical engine thats why.

In most cases this would be one of the resones why. But it is not the only resone.Take a look at the p38. The props do not rotate the direction you think they would to remove a critical engine. It acctualy has 2 critcal engines.

HiTech

[Rolex]

Please forgive my directness, but only the mathematics matters.

Attempts to describe perceived effects, forces or torques applied must be supported by the total system (including aircraft rigging) vector analysis - which will always sum to 0 in equilibrium.

Can we see the mathematics proving the theory that wing-mounted engines apply a rolling moment and torque on an aircraft differently to a single-engine configuration?

[Golfer]

It acctualy has 2 critcal engines.

You can't have two critical engines.  Only one can 'most adversely' affect the flight characteristics.

If they counter-rotate then there isn't one, unless on one powers some sort of system (whether its vaccum, hydraulic, electrical) that will go down that the other engine doesn't have.

And the downward blade on a P-38 is on the outside.  This had to do with the tail's design and so there would be a way, and I may be wrong, to get rid of severe buffeting during certain phases of flight.

[Straiga]

In most cases this would be one of the resones why. But it is not the only resone.Take a look at the p38. The props do not rotate the direction you think they would to remove a critical engine. It acctualy has 2 critcal engines.

Thats aircraft designers, they had no clue untill later.

Until you get some experience in the matter no one here is going to change your mind regardless of you trying to pawn off HTC to us. If you cant afford it I will pay for some time for you we can also probably pass a hat around.

You can't have two critical engines. Only one can 'most adversely' affect the flight characteristics.

You just cant beat flight experience if you did hitech I would be listening and we would be talking about something different know.

Later

[HoHun]

Hi Straiga,

>> It acctualy has 2 critcal engines.

>You just cant beat flight experience if you did hitech I would be listening and we would be talking about something different know.

LOL! I'd say you didn't get the joke :-)

Look at a P-38 with counter-rotating engines with one engine failed.

Then compare it to a P-38 with two equal-handed engines (right or left-handed doesn't matter) with the non-critical engine failed.

What you have is two absolutely identical aircraft. You can tell apart which one is flying on the critical engine and which one has no critical engine only from the memory which way the standing engine turned when it was still turning, but not from any physical reality.

If that doesn't seem funny to you, don't worry, engineer humour admittedly has shortcomings :-)

Regards,

Henning (HoHun)

[straffo]

Originally posted by Straiga
To not have a critical engine thats why. If you had any multi-engine experience you would know that.

Wrong ,if both have the same impact they are equally critical.

It's just pure logic not physic or in-flight experience.

[Straiga]

Wrong ,if both have the same impact they are equally critical.

What do you think I just got through saying.

Off course counter rotating props cancle eachother out with torque, but that isn't the question at hand. Why do you think they make them counter rotating?

Not to have a critical engine. But in P-38 they got it wrong. Twins with counter rotating props that both rotate toward the fuselage do not have critical engine. The P-38 does its prop rotate away from the fuselage. Bad design.

It's just pure logic not physic or in-flight experience.

Ok Spock! You been mind melding to much with that jello bowl. Stop that.

>> It acctualy has 2 critcal engines.

Well I didnt say this and I do get the joke I have been laughing this hole thread long.  

Its funny that Golfer and I have multi-engine experience and everybody who oposes us doesnt, get the point. If you do not have multi time you have no clue, truely you dont. So go get some then will talk.


Straiga

[hitech]

We all know being a pilot makes you an expert in physics. So much an expert you get to change the rules.

And the downward blade on a P-38 is on the outside. This had to do with the tail's design and so there would be a way, and I may be wrong, to get rid of severe buffeting during certain phases of flight.

And at least golfer knows why it wasn't a bad design.


What does get under my skin is you will continue to believe and posibly teaching an incrorect physics principle that moments change based on where they are aplied to an object.

HiTech

[HoHun]

Hi Straiga,

>Its funny that Golfer and I have multi-engine experience and everybody who oposes us doesnt, get the point. If you do not have multi time you have no clue, truely you dont. So go get some then will talk.

Unfortunately, it's not very likely that Newton was wrong and you are right :-)

Considering your professional background, I'd certainly not hesitate to put my life into your hands by flying as a passenger in any aircraft you might control.

However, considering your posts on this board, I feel to obliged to offer some friendly advice: Read up physics 101. Just as Rolex pointed out, mathematics DO matter.

I'm confident that after just a short look at the chapter "forces in equilibrium", everything will come back (and I'm certain you really forgot more about flying than I ever knew :-), and you'll be able to explain your points in a way that actually makes sense even to narrow-minded engineers :-)

Regards,

Henning (HoHun)

[Straiga]

We all know being a pilot makes you an expert in physics. So much an expert you get to change the rules.

No I dont get to change them I just can understand them more by having that experience in flight. Im sorry you dont or wont. Dont get mad because I wont listen to you, Im just laughing that you will find out what were saying if you just go get some multi-engine time. I dont have to prove your wrong. I know whats right but you cant prove me wrong were is your physics, I dont see it, nor your experiences either.

So why dont you get some twin training. Why dont you?

What does get under my skin is you will continue to believe and posibly teaching an incrorect physics principle that moments change based on where they are aplied to an object.

I love getting under peoples skin especialy when Im right. They just get more mad when they find out there wrong. Thats even better.

All the people that I have ever taught how to fly have real experiences and praticality of flight. They dont have armchair certificates in physics. So show me Im wrong with your physics, show me, and when your wrong throughin your RV-8 along with HTC in the bet. You can keep Pyro.

I have to go fly and get more multi-engine time. Stepping on rudder to counter YAW with aileron trim in nuetral. You just have to be there.

HoHun Im not going to try to get Hitech to listen to me. I already know whats right, I fly twins every day, it his turn to prove us wrong. Which he cant do.  

Straiga

[HoHun]

Hi Straiga,

>I already know whats right, I fly twins every day, it his turn to prove us wrong. Which he cant do.  

He already did.

It's just that you need to brush up your physics in order to notice.

Regards,

Henning (HoHun)