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Old May 20, 2011, 09:21 AM
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ogive mod

something like this Frank?
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Old May 20, 2011, 09:28 AM
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another

of course, you could always play with that, to rake the angle more on the LE.
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Old May 20, 2011, 09:33 AM
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Yes that is what I meant, made a sceth. Looks like somehing we all have seen before
Maby the wings should be moved a bit forward.
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Old May 20, 2011, 09:50 AM
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that wing layout is very close to the concord and with the right angles and wash out it might be real fine .
Claus
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Old May 20, 2011, 09:53 AM
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Intake:

Well if the intake is on the side, but still above the wing, then naca will still be able to be used.
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Old May 20, 2011, 09:55 AM
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You are abselut right claus, that is why I did't draw the inlets on the sides.
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Old May 20, 2011, 10:07 AM
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If we like the inlet on top we can do something like this. (just a thought)

But I think it will work better if plased on the bottom.
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Old May 20, 2011, 10:37 AM
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the problem is, you can't put a NACA inlet back there. first reason is that it's behind and on top of the wing, which will cause aero issues, secondly, it's on a tapering section of the fuselage, which means the effect will be poor to none existant. using your last drawing as a reference, an ideal position would be at the maximum point of the fuselage curve, just ahead of the wing root/fuselage junction.

although, if you could somehow make the fuselage coke bottle out a little, before the inlet, I'm sure it would work. still might have aero issues from the wings though. I like the look of that Frank. it looks fast.
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Old May 20, 2011, 11:00 AM
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Quote:
Originally Posted by LuvEvolution7 View Post
the problem is, you can't put a NACA inlet back there. first reason is that it's behind and on top of the wing, which will cause aero issues, secondly, it's on a tapering section of the fuselage, which means the effect will be poor to none existant. using your last drawing as a reference, an ideal position would be at the maximum point of the fuselage curve, just ahead of the wing root/fuselage junction.

although, if you could somehow make the fuselage coke bottle out a little, before the inlet, I'm sure it would work. still might have aero issues from the wings though. I like the look of that Frank. it looks fast.
Most of the losses associated with a low speed inlet, like anything on a model, come from the ducting. If you put the intake that far forward, you will still be losing a lot of efficiency from the length of the duct. The most efficient intake for a low speed unit is the shortest one possible.
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Old May 20, 2011, 11:01 AM
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............and remember, the flow rolls around the fuselage! .....on top is a potentially bad idea, that's why most have the intake on the side / bottom.
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Old May 20, 2011, 11:37 AM
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Perhaps the fuselage would work well utilizing a shape like the Rafale. The feature that I'm talking about is that the bottom is narrow ahead of the intakes, widening out where needed. They don't necessarily need to be set at an angle like the Rafale.



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Old May 20, 2011, 11:59 AM
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If you look closely you can see a space between the inlet and the fuselage, can any one tell me what the function of that is?
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Old May 20, 2011, 12:05 PM
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all planes have this gap Frank. jet engines don't like boundary layer air, especially at higher speeds. this gap between the intake and fuselage takes that boundary layer along the fuselage and directs it around an away from the intake mouth. thus recovering the most amount of energy from the free stream ahead of the intake. if you add the boundary layer to that total, you get a net loss of the free stream total. I've even built this into my 64mm Skyhawk, so I don't injest the boundary layer.

if we use a NACA inlet combination, we won't have to worry about the boundary layer so much, because the inlet will create its own vortex to shed this layer by itself. another win win.
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Old May 20, 2011, 12:23 PM
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Thanks for letting os pick you brain for inofmation, Rich

So Rich, will the naca duct work at it's best if plased on the bottom of the model.

bwoollia, I don't know if it will work maby Rich has some coments.
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Old May 20, 2011, 12:58 PM
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on the bottom...................I would say no Frank. it could if designed properly, but most aircraft are fairly flat along the bottom. as long as the fuselage is expanding, the boundary layer remains thin and attached, due to the increase in pressure. think of it like an airfoil..............the air flows over the top surface and the pressure builds. boundary layer is laminar and thin, but as we get to the peak of the curve, the pressure reduces slightly and the boundary layer starts to thicken and detach, especially as AOA rises. kinda the same thing with a fuse too. pressure builds as the body expands and then tapers towards the rear. for a NACA inlet to work properly, we've got to place it at a point where this pressure is at it's best potential to recover in the duct.
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