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My winter project.

Old 11-04-2002, 03:35 AM
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Default My winter project.

BernieG, here's where I got my information: http://www.aae.uiuc.edu/m-selig/ads/aircraft.

The 8% only appears next to the R-1/R-2 aircraft but it is still listed as a NACA M6 airfoil. However, I'm no expert and will not lay claim to the web site as being infallable either!
Old 11-04-2002, 03:37 AM
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Default Re: Re: Re: elliptical wings

Originally posted by BernieG


huh ! Were did you get that from ? reall spitfires, at least the ones that I have seen up close and personal, HAVE washout !

Bernard
I concur Bernard. Not only do they have it, they have substantial amounts of it.
Old 11-04-2002, 03:42 AM
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Default My winter project.

A quick check of my files shows the Spit wing was set at +2 degrees at the root, transitioning to -1/2 degree at the tip for a total of 2 1/2 degrees of washout. I've flown a number of large scale Spits and none were prone to tip stalling.
Old 11-04-2002, 03:59 AM
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Default My winter project.

Here is a site that says the spit had no washout. Although I'm wondering since the spit was made in so many different versions if we could all be talking about a different one:

http://yarchive.net/air/washout.html

And once again, the spitfire doesn't have true elliptical wings. The model that we are all talking about appears to have true elliptical wings, or pretty close to it.
Old 11-04-2002, 04:03 AM
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Default My winter project.

I am under the impression that this thread started with a design whose dominant value is aesthetic. If its reason for being is its looks, then what place does the discussion of the plane's tip stall characteristic have if the "beauty" of the wing planform trumps all other considerations? There is no doubt in my mind that this design can easily be made to fly and fly well. If it is flown conservatively it will fulfill its reason for being and please its designer and others who value its looks. If the pilot can't or won't, for some reason, fly this plane with plenty of stall margin then my opinion is that the design and the pilot are not a good match for each other.

The goodness of a design can only be fairly judged in the context of the priority of the design objectives. Otherwise the conflict of design objectives can not be rationally desided.
Old 11-04-2002, 05:08 AM
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Default My winter project.

Wow alot has been going on here while I was away at the grindstone.
This Metasequoia program is great, I finally figured out how to save a Metasequoia file as a DXF file that Autodesks' QuickCad
and Autocad R12 can use. Now I can load up a 3D model into Autocad. The trick is to turn off the D3D rendering before saving, (if anyone cares). Quickcad has a good feature that allows printing out a virtually any plan on your printer over multiple sheets.(lots of taping and glueing) oh well.
This is what I've come up with for dimensions for a 40 size to start with:

40" span top
36.5" span bottom
33" length
480 sq. in wing area
80 sq. in hstab area
top wing +2*, 2* washout
bottom wing 0* no washout
4 - 4.5# target weight

If I can get this size to fly well then a bigger one should even fly better.
Old 11-04-2002, 07:30 AM
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Default My winter project.

The M6 airfoil, thinned to 65%, has a nice gentle stall. The full thickness M-6 and the 85% thick versions have an abrupt stall. If you can keep the weight under 4.5 pounds the wing loading will be low enough that the M6, thinned to 65%, will be pleasant to land and take off. The M6 (thinned) inverted performance will be fair but will not give full aerobatic capability. The fat fuselage and biplane configuration are high drag which will limit high speed performance. None of these limitations are serious in a sports model designed for stylish looks.

If you make the struts, flying wires and landing wires functional, the wing spar design to fit in the thin airfoil should not be a challenge.
Old 11-04-2002, 01:50 PM
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Default My winter project.

Originally posted by LoopyLewi

This is what I've come up with for dimensions for a 40 size to start with:

40" span top
36.5" span bottom
33" length
480 sq. in wing area
80 sq. in hstab area
top wing +2*, 2* washout
bottom wing 0* no washout
4 - 4.5# target weight

Those are almost exactly the dimensions of the two Quickie bipes I pictures earlier in this thread:
38"
34"
?
432 sq. in
?
+2*
0*
~3#

Mine are powered with OS .15 FPs and fly nicely, not over powered. I think a 40 would grossly over power them, maybe I'll have to try that!

I'd say don't bother with the washout in the top wing, the difference in incidence softens the stall as does the low aspic ratio, it also easier to build without washout.

What's the fuse diameter? 6~8"?
Old 11-04-2002, 08:31 PM
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Default My winter project.

Originally posted by Chad Veich
BernieG, here's where I got my information: http://www.aae.uiuc.edu/m-selig/ads/aircraft.

The 8% only appears next to the R-1/R-2 aircraft but it is still listed as a NACA M6 airfoil. However, I'm no expert and will not lay claim to the web site as being infallable either!
Just talking from memory here, so it might not be much more reliable than Selig web site....

Bernard
Old 11-05-2002, 04:18 AM
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Default My winter project.

Soarrich, the fuse diameter works out to 8.68".
I also worked out the dimensions if the top wingspan was 50".
The fuse diameter would be 11", the same I believe as Adrian
Pages' R2 model, and lenght would be 41". As a comparison
Adrian Pages' R2 model has a 60" span and is 37" long.
I really think a 40 will definely be needed just to be able to turn a prop that is a little bigger than the cowl. I think a 45 saito four stroke maybe even a better engine for it.
Old 11-05-2002, 06:39 AM
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Default My winter project.

Originally posted by LoopyLewi
Soarrich, the fuse diameter works out to 8.68".........Snip.....
I really think a 40 will definely be needed just to be able to turn a prop that is a little bigger than the cowl. I think a 45 saito four stroke maybe even a better engine for it.

I think your right, .45 Saito sounds like just the thing.


Originally posted by LoopyLewi
I also worked out the dimensions if the top wingspan was 50".
The fuse diameter would be 11"

This is starting to sound really good. I just happen to have a pot...I mean cowl mold, that's 11 inches. I was picturing this with a 48~50 inch set of wings, powered by my new YS 120 or my Ryobi. This my just be the winter project I was looking for.

Are you going to set the top wing on the fuse or have short cabans?
Old 11-05-2002, 03:28 PM
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Default My winter project.

I was gonna use short cabanes or maybe a pylon mount.

The dimensions for a 60-90 size would be:

51.5" tspan
47.5" bspan
42.25" length
11" cowl
808 sq. in. w area
135 hstab area

I think a YS 120 would be awsome in this.
What is the length of that engine?
Old 11-05-2002, 04:31 PM
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Default My winter project.

Slightly slimmed and lengthened.
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Old 11-05-2002, 07:46 PM
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Originally posted by LoopyLewi


I think a YS 120 would be awsome in this.
What is the length of that engine?
It's 6" from the firewall to the propdriver, in the motor mount. It's 4 1/4" from the centerline of the crank to the top of the valve cover.
Old 11-05-2002, 07:53 PM
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Default My winter project.

Originally posted by LoopyLewi
Slightly slimmed and lengthened.
It's hard to see any difference, you're viewing them from different angles. I think the shorter and fatter the better!
Old 11-05-2002, 09:51 PM
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Default My winter project.

As it is drawn right now, it's a perfect fit.
The firewall to the front edge of the cowl is 5.75".
Want the FMS plane to fly in the time being?
Old 11-06-2002, 01:57 AM
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Want the FMS plane to fly in the time being?



I bought FMS on ebay, (I think that what it was called), but I never even put it on my computer. I'm just not a video gamer type. I've bought the MS Air War type games and played them maybe 10 minutes max. I like designing 50 %,and building my own stuff 35%, and flying 15%.
Old 11-08-2002, 06:29 AM
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What I like about the Flight Sim is that after modeling a plane with Metasequoia you can use the simulator to see how it would look flying.
Old 11-09-2002, 05:58 PM
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Default My winter project.

Originally posted by soarrich


I think the shorter and fatter the better!

I have gone with a shorter and fatter fuse. It's real close to that of a Gee-Bee R2. I just can't decide on wether to build gull wings which would eliminate cabanes or regular straight wings or
straight on top and a gull on bottom. Decisions decisions.
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Old 11-09-2002, 06:01 PM
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Any opinions?
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Old 11-10-2002, 04:42 AM
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The double gullwing is a little too much. A lower gullwing with the wheels at the low point like a "Loves Racer" would be cool, but it would have to be no stagger or negative stagger to work. I'm assuming you want this to look as though it was a real plane, not a model, which always have too thin of fuses, or a cartoon plane which seem to always have too fat fuse, but with soft lines.

If you're still making it a .45 powered with a 8" diameter fuse you could mount the wings on the top and bottom of the fuse and still keep the one chord wing separation that is considered minimum for good airflow. I guess it works out the same with the larger plane also. It would be much easier to build without a kink in the wing.
Old 11-11-2002, 03:21 PM
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Thanks soarrich, i think you're right about the double gull being too much. The bird in the bottom pic is the one i'm going to build. For ease a building the first one i'll also have a fuse mounted landing gear and two straight wings, i want this to look like it really could have been a fullsize.
I've been printing out side and top views of it in 25 (7" cowl) ,40 (8")and 60(11") size.
I'll tell you that fuse sure looks big.
Old 11-11-2002, 04:25 PM
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Default My winter project.

Originally posted by LoopyLewi

I've been printing out side and top views of it in 25 (7" cowl) ,40 (8")and 60(11") size.
I'll tell you that fuse sure looks big.
I bet it does! I made a 8" cowl for my 90 size Spacewalker and it looked right on the plane and I thought that was a big cowl. My biggest pot/mold is 10.75 and it's huge, I think to make a 11" cowl I'd have to use lost foam.

Fiberglass Specialties has a generic 11" cowl for $40, also a Mr. Mulligan cowl with blisters for the rocker covers at $45, it's 11" also.

I've got a kit for Mr. M and was thinking of converting it to a biplane, but I've decided that if I do this it will be from scratch.
Old 11-13-2002, 04:20 AM
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Default My winter project.

I'll have to check into those cowls.

I have a question; Is it possible to cut elliptical foam cores? I cannot think of any way that it could be done. I thought i read an article in either RCM or MAN about the subject a few years back but in my move from Northern BC to Southern BC i threw out all my old magazines, so i am unable to check back through them. Thanks.
Old 11-13-2002, 04:55 AM
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Originally posted by LoopyLewi
I'll have to check into those cowls.

I have a question; Is it possible to cut elliptical foam cores?
Yes. The way I understand it is done is by having the foam bent when you cut it. If you cut the top of the airfoil you would want to have the foam bending up in an elliptical curve, but the templates attached to the cutting board. Flip the foam over and cut the top again, you should have an elliptical foam core. By varying the bent and the size of the tip's template you vary the shape of the core. I'm not sure how you figure out how much bend or the size of the tip template to get the shape you want.

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