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B-24 Liberator rudders are angled up


Max89
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I noticed that in many diagrams and pictures of the B-24, the rudders seem to be pointing upwards at a slight angle. I'm trying to figure out where this angle comes from.

 

Are the rudders mounted to the elevator at an angle, or is it the elevator that's mounted to the fuselage at an angle? Or is it both? It's really difficult to tell by looking at the diagrams, and I don't have many useful pictures of the tail to go by, especially ones that show where the elevator and rudders attach.

 

Take a look at the attached image.

 

Any ideas?

 

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Ok, so now I know what it's called. 🙂

 

Anyone have closeup pictures of where the tailplane attaches to the fuselage?' I'm trying to figure out how to model this correctly in 3D.

 

Should I attach the fins to the tailplane at an angle? Or the tailplane to the fuselage at an angle?

 

Was this adjustable on the real aircraft?

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All are correct. The horizontal stabilizers on the B-24 had a positive angle of incidence, which results in the fins and rudders being at the same angle, when seen in profile. The stabilizer incidence was not adjustable, but was fixed, IIRC at 2.5 or 3.0 degrees positive incidence. I think the reason for the positive incidence had something to do with the lift generated by the Davis wing, which I think was only used on the Liberator and  Privateer in WW2.  When I did a 1/72 B-24D by crosskitting an Airfix B-24J and a Revell B-24D many years ago, I used the Airfix fuselage mated to the Revell nose, as the Revell  B-24/PB4Y-1 kits had the stabilizer at 0 degrees. FWIW, the 1/72 Academy and Hasegawa B-24 kits have the correct positive incidence on the horizontal stabilizers.

Mike

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Thank you all for the information.

 

I also just realized that I've been using incorrect terminology all along. I see that the part I was referring to is called the horizontal stabilizer, not the elevator. I understand now that "elevator" only refers to the movable control surface attached to the horizontal stabilizer. :)

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If you are American, it is the horizontal stabiliser.  In English speaking countries it is the tailplane, which has the advantage of being much shorter to type (and less of a mouthful).  

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In Texas, Graham, it's just called the back end! :giggle: (Been sitting here in the Naughty Corner for what seems like ages, and I'm still waiting for @corsaircorp to bring the rocket fuel!)

Mike

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I think it was similar also in Consolidated Coronado. 

consolidated_pb2y_coronado-1.jpg

consolidated_pb2y_coronado-3.jpg

I have noticed it doing the Mach 2 kit...

Regards

J-W

 

 

 

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11 hours ago, Max89 said:

Thank you all for the information.

 

I also just realized that I've been using incorrect terminology all along. I see that the part I was referring to is called the horizontal stabilizer, not the elevator. I understand now that "elevator" only refers to the movable control surface attached to the horizontal stabilizer. :)

Isn’t modeling educational? Yes, it is!

 

In the past, kit instructions would actually refer to parts by their correct names rather than numbers.  We learned the names of all the parts of an airplane before we were out of elementary school simply by building models. 

Edited by Space Ranger
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4 hours ago, JWM said:

I think it was similar also in Consolidated Coronado. 

Never noticed that before you mentioned it, but you are right! The PB2Y did not have the Davis wing, so my guess about the need for positive incidence stabilizers/tailplanes being somehow related to the lift characteristics of that wing is not correct. I ain't no Kelly Johnson, that;s for sure! Speaking of Coronados, and realizing it's off-topic, I sure wish we could get a nice 1/72 injected kit of the PB2Y, other than the $#&^* Mach 2 kit and the Combat Models vacuform, I can't think of another. (Valom or AModel are about the only possible candidate, in my opinion. )I've been up close to the one at the NMNA at Pensacola and it's a BIG flying boat, but handsome!

Mike

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5 hours ago, Space Ranger said:

Isn’t modeling educational? Yes, it is!

 

In the past, kit instructions would actually refer to parts by their correct names rather than numbers.  We learned the names of all the parts of an airplane before we were out of elementary school simply by building models. 

 

Quite educational indeed! :)

Okay, so just to make sure I'm on the same page... do I have this right?

 

spacer.png

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6 hours ago, Space Ranger said:

Isn’t modeling educational? Yes, it is!

 

In the past, kit instructions would actually refer to parts by their correct names rather than numbers.  We learned the names of all the parts of an airplane before we were out of elementary school simply by building models. 

 

I agree Mike - it was an excellent way to learn about aeroplanes. 

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1 hour ago, Max89 said:

 

Quite educational indeed! :)

Okay, so just to make sure I'm on the same page... do I have this right?

 

 

Yes.  Here's the drawing from the Consolidated Service and Instruction Manual B-24D Airplane:

 

20210716-162234.jpg

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7 hours ago, 72modeler said:

In Texas, Graham, it's just called the back end! :giggle: (Been sitting here in the Naughty Corner for what seems like ages, and I'm still waiting for @corsaircorp to bring the rocket fuel!)

Mike

I'm back in nasty corner for a week now...

Are you still digging this tunnel ??

CC

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2 hours ago, 72modeler said:

Never noticed that before you mentioned it, but you are right! The PB2Y did not have the Davis wing, so my guess about the need for positive incidence stabilizers/tailplanes being somehow related to the lift characteristics of that wing is not correct. I ain't no Kelly Johnson, that;s for sure! Speaking of Coronados, and realizing it's off-topic, I sure wish we could get a nice 1/72 injected kit of the PB2Y, other than the $#&^* Mach 2 kit and the Combat Models vacuform, I can't think of another. (Valom or AModel are about the only possible candidate, in my opinion. )I've been up close to the one at the NMNA at Pensacola and it's a BIG flying boat, but handsome!

Mike

From aerodynamic point of view both Coronado and B-24 are very similar one to another. I think that this angle must have some relation to so called pitching moment of airfoil (of wing). The positive angle of incidence on a tailplane (horizontal stabilizer) makes airplane nose go down, so maybe it compensate the pitch moment (but in fact for upper wing machine I would rather expect the opposite direction of pitching moment and therefore the negative incidence angle... ). 

 

I agree that it would be nice to have a newer kit for Coronado, but the Mach 2 one is not that bad as people think on this... :) 

Regards

J-W

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7 minutes ago, don f said:

Yes.  Here's the drawing from the Consolidated Service and Instruction Manual B-24D Airplane:

 

20210716-162234.jpg

That looks to me as though the rudder hinge line is still orthogonal to the fuselage, which makes sense to me. Unless the whole aircraft flies nose down, like a Whitley, which I can’t find any evidence of online, then any deflection of a canted rudder would also result in a pivot of the whole aircraft down to one side or up to the other….

best,

M.

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12 minutes ago, cmatthewbacon said:

That looks to me as though the rudder hinge line is still orthogonal to the fuselage, which makes sense to me.

That is indeed what that drawing shows. Horizontal stabilizer does measure 2.5 deg angler relative to the fuselage top. Fuselage top is horizontal in the drawing. Rudder hinge line is normal (90 deg) to the fuselage top.

 

You learn something new every day! :idea:

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10 hours ago, dnl42 said:

That is indeed what that drawing shows. Horizontal stabilizer does measure 2.5 deg angler relative to the fuselage top. Fuselage top is horizontal in the drawing. Rudder hinge line is normal (90 deg) to the fuselage top.

 

You learn something new every day! :idea:

Sorry, the drawing is only drawing, but all photos show that the rudder hing is skewed by the small angle, it is rather perpendicular to the plate of tailplane...

images?q=tbn:ANd9GcQ3CnVmsiVOqf6G9OVEioL

Regards

J-W

 

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3 hours ago, Corsairfoxfouruncle said:

I was up close and personal with a B-24A this afternoon, hope these help.
 

 

Dennis

 

 

 

"Diamond Lil" is a bit tricky to use as a reference.  You'll notice a slight "kink" where the fuselage meets the tailplane.  This is because she's a very early model B-24, and the roof of the rear fuselage is slightly lower than the later models, sloping back aft of the wings.  I understand the fuselage roof was raised a bit when the power tail turret was added, so it meets the tailplane at the same level. 

 

 

SN

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Nice photos, Dennis! She looks a whole lot better than when the CAF got her from that Mexican petroleum company. A lot closer to her original configuration and appearance. I have yet to see her in her B-24A fit- they do need to lose the CAF logo and Diamond Lil artwork, though. Wanna see what she looked like originally? See the link. As you will read, it was never built as a B-24A, but as an LB-30B.

Mike

 

http://www.b24bestweb.com/lb30-am927-3.htm

 

As flown by Pemex- note the RY-3 nose

http://www.warbirdregistry.org/b24registry/lb30-am927-10.html

 

 

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3 hours ago, 72modeler said:

Nice photos, Dennis! She looks a whole lot better than when the CAF got her from that Mexican petroleum company. A lot closer to her original configuration and appearance. I have yet to see her in her B-24A fit- they do need to lose the CAF logo and Diamond Lil artwork, though. Wanna see what she looked like originally? See the link. As you will read, it was never built as a B-24A, but as an LB-30B.

Mike

 

http://www.b24bestweb.com/lb30-am927-3.htm

 

As flown by Pemex- note the RY-3 nose

http://www.warbirdregistry.org/b24registry/lb30-am927-10.html

 

 

I thought it was an LB-30 ? But all the signs said otherwise so thought I was remembering wrong. Not really liking the PEMEX version, the plane looks all cobbled together. 

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