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Old Oct 20, 2011, 10:05 AM
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Ashford. Kent. England
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Wheels on the "W" heart shaped wing make life easy, I enjoy doing touch and goes..and this one is so easy to keep close , low and slow..
.
KFm4 W wing 21" long Heart shape with wheels KFm4 (4 min 38 sec)
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Old Oct 21, 2011, 11:15 PM
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Ashford. Kent. England
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The Revolution

Here is my latest build.. all cut it waits on fixing..

Edit..... Take note ....after flight testing the heart shape is still the better flying model.. the Revolution was not good at low speed when nose heavy, and it didnt get better when the COG was moved back... and with the COG back normal flying suffered..
This model is fine slightly nose heavy and flying faster.. But again I must repeat, the heart shape is better

I decided to rework the Capricorn, but with my simple size ratio for the sections..
Basic panel sections are made from a rectangle cut at 2:1 ...

My build is using 22x11 inches per section all from 6mm depron, and will be powered with a 150W motor setup..

To make the "W" it takes three sections..
One panel makes the center and it is cut down the middle of its length to make a down fold with a 110 degree angle in it..
The remaining two sections form the tips... make two half delta shapes by measuring 8" up one edge and cutting up to the opposite top corner ..the angle for the tip join is 125 degrees..Elevons can be cut out now or later.. see the plan pic..
chamfer the sections and glue together, use UHU or cool melt , or a combination of both....when all is glued at the correct angles it makes the center layer for the build...
On to this layer the additional front layers top and bottom are directly laminated..this turns it into the KFm4 section wing
Its a chamfer and fit process, laminating with UHU and gap filling with cool melt..
When laminating and gluing keep rechecking the angles to keep them true..
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Last edited by davereap; Oct 26, 2011 at 04:34 AM.
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Old Oct 21, 2011, 11:32 PM
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Ashford. Kent. England
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The Revolution

With the main part done it should look like the picture..

Shape the Leading edge, cut and sand to a sharpish symetrical shape, Now do some taping, use 2" colored packing tape top and bottom along all joins.. Also cover the leading edge..

Make a tail fin , two parts ... and rudder, one part ....to the sizes shown...
Note the tail fins rear part should be 1" deeper than the 6" shown to allow it to slot through the wing and fix to a supporting cross plate... I will show that in a build pic

To fit the rear part of the fin the wing will need slotting, glue the two parts of the fin together..I now fully tape cover the fin with tape before I fit it through.. slot it, fit it, and glue it, use cool melt and make sure its nice and vertical.. Fit a cross brace to the fin and sides of the W... glue and tape.. The front of the fin can be simply glued to the top of the wing..

Elevons and rudder.. chamfer the hinge edges on the elevons , rudder, fin and wings..
fully tape cover the elevons and rudder... use full length 2" wide tape to make hinges..
Tape covering the surfaces will make them stiffer..
For damage resist, against heavy impact stress tears, make sure you have a joined run of tape all across the trailing edge of the wing
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Last edited by davereap; Oct 21, 2011 at 11:55 PM.
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Old Oct 21, 2011, 11:49 PM
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Ashford. Kent. England
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The Revolution

Cutting the parts..
you need 3 off 22x11" panels for the main layer ..mark them up for the positioning of the outer front layers
Next..two sets of outer front doublers to make up the KFm4 wing..
NOTE....Make one set (the lower) just a bit bigger in width by 1/4" , makes the fitting easier

Cutting all the parts take 30-60 mins depending on how slow you take it..

When assembling all the joint angles are eyeballed only and then shaved to get a fair fit.
.They are first glued with UHU POR and then all the joints are filled or beaded with cool melt adhesive..

At every stage double check the angle, holding it correct, whilst beading the joint with the cool melt
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Last edited by davereap; Oct 22, 2011 at 12:55 PM.
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Old Oct 22, 2011, 02:17 AM
flyin' fool
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Vancouver Island, Canada
Joined Jul 2003
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Quote:
Originally Posted by davereap View Post
Wheels on the "W" heart shaped wing make life easy, I enjoy doing touch and goes..and this one is so easy to keep close , low and slow..
Great, wonderful............now, let's see you do all that inverted.
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Old Oct 22, 2011, 12:22 PM
ChuckB
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United States, CA, Santee
Joined May 2004
139 Posts
Revolution

Your new design looks great. We have a person here in San Diego has the original version from way back when???? I cannot believe how well it flies. Looking forward to your new build version (Revolution). Would like to build one myself. Do you have any plans to Tile them in pdf format? Or will you have the correct angles for the cuts from 6mm depron? Regards, ChuckB
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Old Oct 22, 2011, 12:41 PM
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Ashford. Kent. England
Joined Feb 2005
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All I do, is the drawing lines in sketchup, and leave the build to you...
As you will see from the pics ive just posted each section is chamfered by eye only, to be a fair fit.. Its a slow process, but not to hard to get reasonable..
Panels are trimmed, and overlapped as you see fit.. the end result is a good stiff wing..

note the panels on top always end up having to be trimmed down from the basic shape sizes, whilst those on the bottom need making about 1/4" over size ... either way there ends up bits trimmed off..

As it is the airframe weighs 7 1/8 oz and it has an area of 3.97sqft...

more tomorrow...
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Last edited by davereap; Oct 22, 2011 at 12:59 PM.
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Old Oct 22, 2011, 01:36 PM
ChuckB
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United States, CA, Santee
Joined May 2004
139 Posts
Dave,
Thank you so much for the quick response. I am going to build one. Are you going to put landing gear on it? If so, could you show you method of installation? On the kfm4 airfoil did you use 6mm on the main part and 3mm on the kfm airfoil? Sorry about asking so many questions but being retired like you I don't want to waste money on mistakes. You seem to have this down to a refined system in your build. Also what will you cg be? Happy flying, ChuckB
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Old Oct 22, 2011, 03:05 PM
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Dave, I am glad you took the delta direction. It is saving me the trouble. When I get around to it, it will be done already!!!!! Looking good
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Old Oct 22, 2011, 03:07 PM
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Where did you get your angle measuring device?
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Old Oct 23, 2011, 02:50 AM
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Ashford. Kent. England
Joined Feb 2005
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The measuring device came from a model shop... under a 5..
its a handy gadget

I had a PM question on wing angles so Ive done a simple drawing to clarify...

On the heart shape I used 110 at the center and 135 at the tips..
and on the delta shape I used 110 and 125..
The angles are the angle in the V where each part is joined

So the new delta has different angles and the maiden will show if it works...
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Old Oct 23, 2011, 03:00 AM
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Ashford. Kent. England
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Quote:
Originally Posted by ChuckB View Post
Dave,
Thank you so much for the quick response. I am going to build one. Are you going to put landing gear on it? If so, could you show you method of installation? On the kfm4 airfoil did you use 6mm on the main part and 3mm on the kfm airfoil? Sorry about asking so many questions but being retired like you I don't want to waste money on mistakes. You seem to have this down to a refined system in your build. Also what will you cg be? Happy flying, ChuckB

Landing gear...YES .. see post 60 for the way I did the heart shapes gear.. Its a simple rectangle fixed up in the center of the W .. to which I fix 2 strips of velcro ..the UC fixes to that...
See http://www.rcgroups.com/forums/showthread.php?t=937395 fo a suitable two or three wheeled system...

COG the Heart shape is back to just in front of the 30% measured from the nose..The delta is to be found but I will start in the same area..

Sizes for depron... I have tried a few methods all have been good...
The easy method is all 6mm directly laminated..thats what Ive done on the latest 22" long delta version, and its made a nice strong stiff wing...
It depends on what you have available.. and the size you want to build..
I expect it also makes a difference to the final weight.. However as I bunged on a couple of extra ounces with the UC system and that has not affected the performance, I wouldnt worry too much.
On the heart shaped 21" long version I used all 3mm depron, but at the steps I added 3mm balsa spars to raise the step to 6mm deep... Go back and see the pics at post4 pic6 for the construction
I think 3mm as a step depth is not enough on a sport power model.. 6mm is a minimum here..

For outside foamie sports model types I aim at having a wing loading of arround 4 ozsqft..and a weight of 12-20 oz ..
lower will fly slower and vice versa..
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Last edited by davereap; Oct 23, 2011 at 03:17 AM.
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Old Oct 23, 2011, 07:38 AM
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New Hampshire-seacoast area
Joined Jun 2005
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Thanks for the clarification Dave.

Being rather thick at times, I thought when you said the BW size heart shaped one was built based on a 21X10.5 inch panel, you meant the entire "panel " you started with was 21x10.5. So I cut one out of a blucore panel that size. Well it came out real dinky when folded up!.

Then I figured out the BW sized one was actually 30x21 when made from a single sheet of FF.

It's tough gettin' old LOL
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