Thrust line, wings and stab
12-06-2005 | 08:07 AM
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From: SantiagoReg Metropolitana, Providencia, CHILE
Thrust line, wings and stab
Pattern planes have obiously evolved for good, that`s a fact, but I can`t figure out why all modern planes have the thrust line on top then the stab and then the wing (way down), thinking in the vertical order or placement of the surfaces
any ideas?
any ideas?
12-06-2005 | 08:39 AM
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From: , ITALY
RE: Thrust line, wings and stab
Great questio Daniel! Let's wait the "big guns" to answer!
I have an idea about this, but I'm not an expert of the aero field. Let me try to explain that...
I think by raising the thrust line the designer tries to split the fuselate side area in two parts (up and down the thrust line) such that these two areas are equal.
Why? If the spiraling prop stream is centered on thrust axis (which I think it is true), then by doing so the plane will require much less right thrust (at the limit of equal side area up and down, you could end up with no right thrust required)
But now let's wait an opinion of some expert...
I have an idea about this, but I'm not an expert of the aero field. Let me try to explain that...
I think by raising the thrust line the designer tries to split the fuselate side area in two parts (up and down the thrust line) such that these two areas are equal.
Why? If the spiraling prop stream is centered on thrust axis (which I think it is true), then by doing so the plane will require much less right thrust (at the limit of equal side area up and down, you could end up with no right thrust required)
But now let's wait an opinion of some expert...
12-08-2005 | 02:36 PM
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From: SantiagoReg Metropolitana, Providencia, CHILE
RE: Thrust line, wings and stab
Stek,
caps have a very "on top" thrust line, and as I read there are people putting UP thrust on them, maybe in this sweet spot you mention there is no need for down thrust too; but why the stabs are lower than older planes? older planes used to have it ON the thrust line
need more opinions!!
caps have a very "on top" thrust line, and as I read there are people putting UP thrust on them, maybe in this sweet spot you mention there is no need for down thrust too; but why the stabs are lower than older planes? older planes used to have it ON the thrust line
need more opinions!!
12-08-2005 | 03:45 PM
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From: , ITALY
RE: Thrust line, wings and stab
Hello Daniel,
regarding stabs height, I don't know. We have to wait some expert to come here...
For the up thrust question, I'm quite sure it depends both on thrust line placement and fuselage shape: in fact, planes are not symmetric with respect to fuselage frontal area. If we have more surface under the thrust line, a torque will originate since the lower portion of the airplane is generating more drag than the upper. So the up thrust is used to overcome this issue. I don't own a fixed gear pattern plane, still have a retract one, but with the fixed gears wheels and pants are all generating drag with a good arm with respect to thrust line, and I bet that with those planes less down thrust is required, or up thrust actually.
I don't know if there are other effects, however.
regarding stabs height, I don't know. We have to wait some expert to come here...
For the up thrust question, I'm quite sure it depends both on thrust line placement and fuselage shape: in fact, planes are not symmetric with respect to fuselage frontal area. If we have more surface under the thrust line, a torque will originate since the lower portion of the airplane is generating more drag than the upper. So the up thrust is used to overcome this issue. I don't own a fixed gear pattern plane, still have a retract one, but with the fixed gears wheels and pants are all generating drag with a good arm with respect to thrust line, and I bet that with those planes less down thrust is required, or up thrust actually.
I don't know if there are other effects, however.
