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WINGITIS

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A normal NACA 0015 has good CM(POSITIVE) but a lower lift and more drag than the best of the others......as well a sonly low to fair LD, at the speed/chord we are testing.

Not sure about the 0015-64 they mention, I cannot find it co-ordinates.
Heres the basic calcs for the DM1 at 52MPH, it has a Mean Geometric Chord of 10.97 feet with a span of 19.6 FT.

The mean Chord value RN value is 5,270.985.

It needs only a lift coefficient of 0.45 to maintain level flight at 300KG.

This is less than before BUT its because it has nearly twice the wing area at 215 SQ FT that is a lot more than a Cessna 150's 160 SQ FT...

Hardly portable....

Scaled down to the same 12 Foot Span as the other plan forms, it only has an area of 81 Sq feet.....RN 3,200,000

It would need a lift co-efficient of 1.2 for level flight...it would be at AOA 10 degrees with the Horten airfoil at that point.....or 11 degrees with the basic 0015....

Perhaps not ideal.

DM1 LIFT CALCS.png
 

WINGITIS

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Heres the basic calcs for the DM1 at 52MPH, it has a Mean Geometric Chord of 10.97 feet with a span of 19.6 FT.

The mean Chord value RN value is 5,270.985.

It needs only a lift coefficient of 0.45 to maintain level flight at 300KG.

This is less than before BUT its because it has nearly twice the wing area at 215 SQ FT that is a lot more than a Cessna 150's 160 SQ FT...

Hardly portable....

Scaled down to the same 12 Foot Span as the other plan forms, it only has an area of 81 Sq feet.....RN 3,200,000

It would need a lift co-efficient of 1.2 for level flight...it would be at AOA 10 degrees with the Horten airfoil at that point.....or 11 degrees with the basic 0015....

Perhaps not ideal.

View attachment 99891
Note also that as you have sweepback the relative velocities across the chord reduce and that changes the RN and reduces the lift generated for the same forward speed(ATTACHED). Which I have not included in any calculations presented to you thus far.

SWEEPBACK VELOCITIES.png
 

WonderousMountain

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X-foil has a linear component increase per %thickness supposedly to account for added skin friction drag. While the other effects are a greater magnitude, It's worth noticing. I set my foils to 13.5% thickness & .75cl cruise. Usually the focus was .25% span. These were high lift with slotted flaps, I forget the types name.

Anyway, it was no trouble at all to improve LD, by dropping to 12% Chord. Good sailing Character was almost unobtainable 17.5% and above. If you have a thick foil, you can sometimes reduce Camber for overall performance. The Naca 6 series had better results with 40% Max thickness, but this was not chosen often until it was outdated.

You can't get the best performance out of a reflexed foil, but
a late transition & matched velocity trailing edge will get close.

The difficulty, really is span transition, .2-.8 semi-span
the tip & root are drag coves, you just have to accept.
 

pictsidhe

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A different reflexing mean line would help my airfoil. The 67 mean line would be well worth trying, but it isn't in my spreadsheet yet.
Don't get too hung up on L/D. Once you add n the parasitic drag of the everything else, it's effect diminishes.

Here's the 15% version of it.
Hi FOLKS

Here is the analysis of that wing I posted with a 300KG load at various speeds and AOA.

With a 13 foot wingspan its not to bad, but obviously there is no extra drag or loss of lift from attaching an engine, undercarriage and person etc etc.

But it will give you some idea .as to what sizing may work.....

Cheers
Kevin
At 40mph, it will have over 300kg of induced drag. Yes, the aircraft weight in induced drag. You'll probably need over 200hp to maintain level flight at 40mph.
At 52mph looks like around 120hp for level flight. At 104mph, induced drag will eat a bit over 30hp. Looks like far too much opportunity to get behind the curve to me.
 

pictsidhe

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A different reflexing mean line would help my airfoil. The 67 mean line would be well worth trying, but it isn't in my spreadsheet yet.
Don't get too hung up on L/D. Once you add the dragS of the everything else, it's effect diminishes.

Here's the 15% version of it. I'm going to try and add 4 digit camber lines to my spreadsheet now.
 

Attachments

WINGITIS

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A different reflexing mean line would help my airfoil. The 67 mean line would be well worth trying, but it isn't in my spreadsheet yet.
Don't get too hung up on L/D. Once you add n the parasitic drag of the everything else, it's effect diminishes.

Here's the 15% version of it.
At 40mph, it will have over 300kg of induced drag. Yes, the aircraft weight in induced drag. You'll probably need over 200hp to maintain level flight at 40mph.
At 52mph looks like around 120hp for level flight. At 104mph, induced drag will eat a bit over 30hp. Looks like far too much opportunity to get behind the curve to me.
No attachment?

D = .5 * Cd * r * V^2 * A

CD and Area of the wing FACE are both issues.

The lower CD and lower thickness are both better!

R and V^2 are constant in this test case.

Area under the L/D curve shows the actual performance in the whole flight envelope...
 

pictsidhe

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No attachment?

D = .5 * Cd * r * V^2 * A

CD and Area of the wing FACE are both issues.

The lower CD and lower thickness are both better!

R and V^2 are constant in this test case.

Area under the L/D curve shows the actual performance in the whole flight envelope...
Parasitic drag is calculated using wing area, not wing face area.
 

WINGITIS

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Go to Aircraft Design / Aerodynamics / New Technology and choose "Post new thread." You can ask the moderators to move posts from this thread to the new one, just specify which ones. Cheers, Matthew
Hi Matthew

Ok have worked it out and implemented:

ACHIEVING THE BEST REFLEXED AIRFOILS FOR FLYING WING USE IN THE SMALL PLANE CATEGORIES

I will order some of the items in a better way and repost them i think..

Cheers
Kevin
 

WINGITIS

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A different reflexing mean line would help my airfoil. The 67 mean line would be well worth trying, but it isn't in my spreadsheet yet.
Don't get too hung up on L/D. Once you add the dragS of the everything else, it's effect diminishes.

Here's the 15% version of it. I'm going to try and add 4 digit camber lines to my spreadsheet now.
Ok, Pictsidhe I have downloaded that now and analysed it.

Are you happy for me to include your Airfoils in the new Thread?

Cheers
Kevin
 

rotax618

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My observation comes from experimentation with models, I have no empirical data as such, It is just another observation, but Avro Vulcan lands slower than a B52, and it has no high lift devices fitted to its wings.
 

poormansairforce

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My observation comes from experimentation with models, I have no empirical data as such, It is just another observation, but Avro Vulcan lands slower than a B52, and it has no high lift devices fitted to its wings.
Well, it has half the wing loading at empty weight and less than that at max.
 

rotax618

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You are right, perhaps my comparison of two subsonic nuclear bombers wasn’t the best but low aspect ratio requires a much lower wing loading to perform, my attempts at comparison was high aspect ratio/span loading versus low aspect ratio/wing loading/planform. Obviously we will never see a LAR man powered aircraft but for a simple single seat sportplane LAR offers some benefits including a very low landing speed.
 

BigBen

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