Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

an Idea for the leading edge

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Old 09-15-2008, 05:18 PM
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Dead Roman
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Default an Idea for the leading edge

I was thinking about taking some small strips of balsa and sanding the leading edge of the wing on my world models p-51 down to a much finer edge than is already in place. I figured this might cut the wind resistance down a bit. Am I crazy thinking this should work, would there really be any benefit?
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Old 09-15-2008, 06:09 PM
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Default RE: an Idea for the leading edge


ORIGINAL: Dead Roman

I was thinking about taking some small strips of balsa and sanding the leading edge of the wing on my world models p-51 down to a much finer edge than is already in place. I figured this might cut the wind resistance down a bit. Am I crazy thinking this should work, would there really be any benefit?
It may reduce the drag of the wing somewhat. As you sharpen the LE of an airfoil you generally tend to make the stall behaviour progressively more abrupt, so beware of that caveat. The frontal area of that aircraft has a lot to do with the total amount of drag, so the potential for speed gain may be so small you would wish you had left the airfoil alone.

Just things to consider. If anything, don't go too nuts on the LE.

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Old 09-15-2008, 07:58 PM
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Default RE: an Idea for the leading edge

I wouldn’t mess with the LE, if you are looking for speed think about fairings where the wing meets the fuse, clean gear doors, gap seals on the control surfaces, sharpen the trailing edges and maybe a retract tail wheel ( not much gain with the tail wheel). Or…… get an even bigger engine.
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Old 09-15-2008, 08:57 PM
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Default RE: an Idea for the leading edge

As both who answered before said changing the leading edge will not help you much.
Your bet be is to clean up the airframe as noted sealing gaps, sharpening the trailing edges, retract the tail wheel, and alike, these are going to give you the best return for your effort.
Putting fairings on the control rod exits, along with fillets on the tail surfaces, may also help to reduce drag a bit.
I am no expert by any means but had asked some questions regarding a purpose built speed airplane a while back in the aerodynamics forum, you may want to see some of the replies from guys who deal with speed planes, as to what some of the secrets are...


More power....
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Old 09-15-2008, 09:14 PM
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Default RE: an Idea for the leading edge

The best of both worlds may be a sharp leading edge inboard and a rounded leading edge outboard. Would work like stall strips. However, most leading edge shapes are there for a reason and altering it may hurt more then it helps.
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Old 09-15-2008, 09:49 PM
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Default RE: an Idea for the leading edge

One more way to cut down drag is to clean up the air flow through the cowl. On my WM Dago Red I made the chin opening smaller, and added baffles around the cyl. and a fairing behind the cyl. to allow the air to exit more efficiently.

JMO but I wouldn't mess with the L.E.
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Old 09-16-2008, 11:53 AM
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Default RE: an Idea for the leading edge

Sharp leading edge is bad !!!

It does not help speed. You want the LE that provides the correct airflow over the airfoil used... that makes the wing work efficently.

Sharp LE = VERY pitch sensitive - the air can not decide which way to go for a very simply visualization.


Please do not confuse the sharp razor edges you may have seen on 1960s era fighter/interceptor aircraft as something related to speed. They were necessay for the supersonic flight environment. But they also caused take off and landing speeds that were WAY up there.

Models (and most aircraft) fly extremely sub-sonic.

The suggestions of others here will help you gain some speed. Get rid of drag where you find it.
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Old 09-16-2008, 04:10 PM
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Default RE: an Idea for the leading edge


ORIGINAL: proptop

One more way to cut down drag is to clean up the air flow through the cowl.
On my WM Dago Red I made the chin opening smaller, and added baffles around the cyl. and a fairing behind the cyl. to allow the air to exit more efficiently.

JMO but I wouldn't mess with the L.E.
A rather big source of drag!
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