albert einstien

[df54]

could someone please summon albert einstien from his grave and explain (in layman's terms please) how an object with a large mass(lets say a f4u-4) can turn a smaller circle than an object with a smaller mass.

[TheThang]

Because there is more force pushing it that direction that the smaller object has.   Ex.    its a 4 kg plane vs a 2 kg plane (example!)   The elavator, wings, and flaps are pushing the small 2g plane with a force of 40N <<< way.  While over here we have the 4g plane because pushed 160N <<< way.  The small planes only being pushed at twice its weight while the big one is being pushed at 4x its weight. The big one is going to Want to overcome inertia that much more and thats why it turns that way.

I probably just explained that horrible.

[Major Biggles]

f4u-4 is heavy but very powerful, it has a monstrous motor. it's wings, and it's flaps will create a considerable amount of force as lift. it may be heavier, but the force from the engine, and from the wings is going to be greater than that of the smaller, lighter plane.

this means that the f4u can turn with much more nimble and lighter opponents

[df54]

Ok, then with full flaps the f4u is being lpushed farther inward(toward the axis of rotation) which results in a smaller turn circle. By the way how do you spell Al's name?

[df54]

Ok' then the f4u with its hp can overcome all the forces trying to pull it outward  from the axis of rotation.

[Murdr]

It's not always about turn radius.  Rate of turn is also a factor.  A plane with a larger turn radius could "out turn" a plane with a smaller turn radius if it's rate of turn is better.

Radius points are rarely at the same spot in a dogfight.  A plane with a larger turn radius can appear to "out turn" a plane with a smaller turn radius with the use of lag pursuit to place its turn radius at a location where they can intercept the tighter turning plane.

That said there are a number of factors that can affect turn radius including speed, wing loading, power loading, lift coefficent, total drag, to name a few.  While it's not wrong to assume that a ligher AC should be able to pull a tighter turn, the conclusion is not always 100% correct.  Much depends on the factors that can vary.

[df54]

We are talking instantaneous turn rate not sustained rate right?

[Murdr]

Originally posted by df54
Ok' then the f4u with its hp can overcome all the forces trying to pull it outward  from the axis of rotation.

Umm no.  Let's assume we are talking about a sustained flat turn for F4u4.  Its angle of attack is going to be limited by its maximum coefficent of lift.  So that's one thing that limits its turn radius.  

Another thing that's going to limit it's flat turn radius is going to be its bank angle.  It's bank angle is going to be limited by its speed.  The less speed it has, the less bank angle it can hold without stalling.  What is affecting its speed is the excess drag being induced by the high angle of attack.  

Here is where the horsepower comes in to play.  The more HP or more correctly thrust you have availible to overcome the total drag, the more speed and therefore bank angle you can hold.  The more bank angle you can hold, the tighter the turn radius you can sustain indefinately.


Now on the other hand if we are talking instantanious turn rate, then we are back to the relativity of factors in my first post.  Max AoA, and G loading the pilot and wings are going to be limiting factors, and depending on relative speeds a heavier plane could very well out turn a lighter plane under the right conditions.

[Murdr]

My point in the first post was that there are situations were a plane with a larger turn radius can "appear" to turn tighter than a tighter turning plane, when its actually a case of positioning or rate of turn.

[bozon]

We are talking instantaneous turn rate not sustained rate right?

Sustained turn rarely happens in a dog fight. It happens either when the pilots don't know what they are doing or the fight got down to the deck and speeds dropped to near stall.

Don't delve too deep into these turn rate/radius numbers. People do very interesting tests to meaure this, and argue till they are blue in the face, but in practice, unless the difference is huge, it doesn't really matter.

In most cases, the acm performed and the geometry of the flight paths will make a much bigger difference. Those are pilot controled and so the pilot is more important than the plane. The plane helps, yes, but it is secondary.

[trotter]

TheThang is that a Yatta reference I see in your info?

[Keiler]

Originally posted by df54
By the way how do you spell Al's name?

Like "Yneshtyne"

Matt

[Murdr]

Originally posted by bozon
Sustained turn rarely happens in a dog fight.

Tell that to the KoTH participants

[Nomak]

Originally posted by df54
could someone please summon albert einstien from his grave and explain (in layman's terms please) how an object with a large mass(lets say a f4u-4) can turn a smaller circle than an object with a smaller mass.

I am prepairing a training film that will hopefully explain exactly that.  I have a swarm of ideas on how to convey this information to the AH masses.  I am hoping to post this film sometime in the next week or so.

Dave

[Major Biggles]

Originally posted by Murdr
Tell that to the KoTH participants

too right!