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View Poll Results: Model platform
Delta 88 57.52%
Non Delta 65 42.48%
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Old May 20, 2011, 02:08 PM
You win again gravity!
SMorrisRC's Avatar
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Joined Jan 2010
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Quote:
Originally Posted by LuvEvolution7 View Post
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.
I think if it's on the top there's a real risk that you won't be able to ingest enough airflow to the fan. Especially so in any form of high alpha flight (a sharp turn, for example). The NACA inlet, whilst low drag, is already at the disadvantage of having almost no ram effect, which is why it isn't used for jet intakes on full-size aircraft - only for ventilation / cooling flows, combine this with the flow wrapping up around the cylindrical fuselage and you'll struggle to get a useable amount of air on the upper side in normal flight. In high alpha, you have twice the problem in that the intake is now shielded from the airflow by the fuselage.
The 'hybrid' type of intake, sticking out a little, will of course help, but I think placement is going to be crucial.
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Old May 20, 2011, 02:11 PM
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St.Catharines, Ontario
Joined Jan 2009
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Bd5

I'm looking at the 3 view of the BD-5 and if you notice, the NACA inlet starts just after the fuse starts to narrow again. I've checked this against better drawings/photos and it appears that this 3 view has the inlets a bit too far astern. photos show the inlets to be at the point where the fuse is the widest.
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Old May 20, 2011, 02:13 PM
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Quote:
Originally Posted by SMorrisRC View Post
I think if it's on the top there's a real risk that you won't be able to ingest enough airflow to the fan. Especially so in any form of high alpha flight (a sharp turn, for example). The NACA inlet, whilst low drag, is already at the disadvantage of having almost no ram effect, which is why it isn't used for jet intakes on full-size aircraft - only for ventilation / cooling flows, combine this with the flow wrapping up around the cylindrical fuselage and you'll struggle to get a useable amount of air on the upper side in normal flight. In high alpha, you have twice the problem in that the intake is now shielded from the airflow by the fuselage.
The 'hybrid' type of intake, sticking out a little, will of course help, but I think placement is going to be crucial.
I agree. if it's on top, we're going to get into all sorts of aero issues. if we're going to use a hybrid intake, it's got to be on the side, or the bottom. if it's on the bottom, it's got to pitot style only, as I doubt a NACA inlet will do any good. if we go with a bottom design, we could always neck up the fuselage a bit, to minimize cross section.
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Old May 20, 2011, 02:15 PM
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Denmark
Joined Sep 2005
867 Posts
Thanks again.

Got it now(slow learner)

If the looks of the model may be a bit od. I think I have an idear to help the NACA duct handling AOA. My idear is to have it as in/or clouse to the nose, split it op in two parts- one on top and one on the bottom.
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Last edited by frank40; May 20, 2011 at 02:36 PM.
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Old May 20, 2011, 02:19 PM
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St.Catharines, Ontario
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intake

if we use a bottom intake with a necked up design, I'm guessing it would look something like this. yes it's crude, but it serves its purpose. LOL.

we won't gain much by necking in the fuse, but anything is better than nothing if you want to go fast.
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Old May 20, 2011, 02:37 PM
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So it seems that the inlet should be on the sides, right.
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Old May 20, 2011, 02:40 PM
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depends what we're going with. if it's a NACA hybrid, then the side makes more sense aerodynamically speaking. or if there's some way to make it a part of the nose, that could work too. top or bottom is pretty much out.

if we're going with pitot style inlets, they can be wherever they fit the design the best. it might be prudent to design the best shape around the inlets and wing planform that we choose. I think the inlets and ducting are the most important part..............kinda like designing an A-10 around the gun.
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Old May 20, 2011, 03:26 PM
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LOL

Here is the laste sketch for tonight, with the inlet on the sides. see you
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Old May 20, 2011, 03:42 PM
Low rates are for wimps
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United States, CO, Colorado Springs
Joined May 2008
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Awesome. I'd fly that.
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Old May 20, 2011, 05:06 PM
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me too.
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Old May 20, 2011, 07:34 PM
Life begins at transition
Australia, VIC, Sale
Joined May 2007
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Looks like a mirage got busy with a concorde
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Old May 20, 2011, 08:34 PM
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Fairborn, OH
Joined Nov 2009
544 Posts
More like a Delta Dart and a concorde (the trailing edge of the Mirage is a 90 degree angle while the Convair designs like the Delta Dart and Hustler had the trailing edge angled more toward the tail). I like it.
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Old May 21, 2011, 07:33 AM
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Denmark
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Glad you liked it I moved the wings a bit forward, to get the CG clouser to mid fuselage.

I have posted a drawing so we can make some different looks on the side view, so go nuts......

By the way you can stop voteing, the platform is decided. But I can't stop the poll sorry.....

I am looking for idears to votes we need to do in the future, seens I can't stop the poll we need another way to do it.
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Last edited by frank40; May 21, 2011 at 07:39 AM.
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Old May 21, 2011, 08:13 AM
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Just a pic.
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Old May 21, 2011, 08:56 AM
michigan jet guy
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USA, MI, Caledonia
Joined Jul 2007
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that is cool.
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