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solentlife


Ok then, can't wait to hear how it performs.


That will be a while yet as I am trying to get the FRC Lanc finished .... but Banks and work are getting in my way !

But I can say .... I am thinking to make the fuselage and booms in box form as profile are going to be extremely weak, even if I laminate two 6mm depron together.

I would be surprised if this could survive in 3mm depron at 20" span ... those booms would be very weak even with CF.
I'll fly anything if I can launch it ! Youtube : solentlifeuk
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DualDesertEagle
solentlife wrote:

I am thinking to make the fuselage and booms in box form as profile are going to be extremely weak, even if I laminate two 6mm depron together.

I would be surprised if this could survive in 3mm depron at 20" span ... those booms would be very weak even with CF.


With 2 sheets of 6mm it should be more than strong enough, the fuselage with its horizontal piece at least.

The Wings on my MiG-29 are only 2 layers aswell, one of which is the wing itself and the other is the KF-airfoil, which of course only covers some area at the front of the wings. And those are damn strong even without any carbon rods whatsoever.
20191018_131750.jpg 
Even holding it that far out on the wing it barely flexes under the plane's weight. And the KF only covers about 40% of the wing chord.


And the reason why I would reinforce the tail booms with a carbon rod is that the real ones are so slim that I wouldn't wanna weaken the vertical pieces with a slot that goes like half way along their prop axis to fit in a horizontal piece that would do little more than a carbon rod. That's why I only made horizontal pieces to go on their front and provide lateral support for the motor mounts.
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solentlife
If you look at my Vulcan ... and Hawker Hunter .... they are based on laminated 2x6mm depron to 12mm .... 

Yes they are a lot stiffer, but having seen too many twin boom models fail ... I'm wary of trusting without more structure. I think going for a box form can really enhance the strength factor as well as giving a wider mount area for the motors etc.
I'll fly anything if I can launch it ! Youtube : solentlifeuk
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FeWOlf
All I can say is thanks alot, I am leaving for Las Vegas Monday, Military Reunion, so I will start when i get back, i have 5mm poster board.
I can always upscale and descale.
Fly Like Hell, and you will get there!
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FeWOlf
solentlife wrote:


That will be a while yet as I am trying to get the FRC Lanc finished .... but Banks and work are getting in my way !

But I can say .... I am thinking to make the fuselage and booms in box form as profile are going to be extremely weak, even if I laminate two 6mm depron together.

I would be surprised if this could survive in 3mm depron at 20" span ... those booms would be very weak even with CF.


between my lamination, I insert a Bamboo Skewers 30" on boons front to back, and also on the wing, I built one similar to this out of blue core foam and ran packing tape along the leading edge, you can also run a skewer on the edge, this will give you a rounded edge, using hot glue and packing tape. Shiftens up your wing and make it more durable for air combat. I have also inserted before in my lamination, thin balsa sheet or plastic sheet.
Fly Like Hell, and you will get there!
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FeWOlf
This is the place that got me started on the profile planes, lots of tips and planes, https://www.rcgroups.com/forums/showthread.php?724566-Printed-Warbirds-and-more-Part-2
Fly Like Hell, and you will get there!
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DualDesertEagle
Any progress here?
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FeWOlf
Any progress here?

Sorry no, since I got back I have been hammered I do have it printed out and picked up more Readi Board, going to try and hit it next week, going hobby shop and picking up some balsa sheet and I have some 30in Bamboo rods and some heavy foam board at Hobby Lobby, I will be on the road on the weekend. I ran into the same issue, it is 52in long, I will be down scaling it to 30in wing span. I will decide on what bracing it will need as I build, I use KFm2 so wing support should not be an issue, as in most Twin Boon it is the booms that are the issue.
Fly Like Hell, and you will get there!
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DualDesertEagle
FeWOlf wrote:
 I use KFm2 so wing support should not be an issue


Yeah, I was gonna suggest that if the question would arise.
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solentlife
I know some are ardent KFm users ... but I've never seen any advantage in models I've built. In reading up about KFm development - in the full size world they found it had limited range of effectiveness, such that it never really took hold. 

My use of it has been on big wings such as my RC Eagle purely to add to the stiffening and for that particular model - add the 'feathers' effect ! Its as good as adding another CF spar.

Another way to stiffen a wing - is to laminate with thin nylon + epoxy between the layers. For a 6mm build - laminate two 3mm sheets with that thin nylon and epoxy - the result is amazing. I built a Polaris using this and that wing survived everything ... in fact the rest of model gave out around it with the abuse I gave it.

Note the epoxy is the thin laminating variety - not the two tubes 5 .. 30min stuff. You literally paint it on ... lay the thin nylon (window net or dressmakers lining) on ... place second sheet on and then weights all over to press the two together. Leave to cure overnight.
I'll fly anything if I can launch it ! Youtube : solentlifeuk
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FeWOlf
I use the Gorilla Glue White, and very thin balsa sheet, or even wrap the wing in elmers glue/water and brown paper or newspaper, also your dry mesh and elmers thinned out, excellent strength and use can sand it, 
Fly Like Hell, and you will get there!
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solentlife
I can only get Exterior grade PU glue here ... which is slightly heavier than the interior white grade.

I did try PU laminating - but it needed whole area weighting to avoid 'bulges' from the expanding 'foam'. 

The epoxy has a greater physical strength for thinner film as well.

I've never used paper with PVA ... I used thin net curtain with PVA on my Badius ... which is now able to withstand WW3 !!

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then sprayed ... 

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I'll fly anything if I can launch it ! Youtube : solentlifeuk
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FeWOlf
I am working on it now, setting up the original picture to skin it, which is taking time and slow. I did the paper/glue test, my plane became a lawn dart, the only thing, what I paper/glue was wing, it was the only thing that made it. I also airbrush, so it has been nice to use the paper/glue, really holds color, I have been know to over engineer, going to have to do some glide test, and make sure on the CoG.
Fly Like Hell, and you will get there!
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DualDesertEagle
Well strength wise I can only agree that the KF airfoils can add A LOT to an otherwise very flexy wing, as I've demonstrated using the picture in which I held my MiG-29 V1 pretty far out on its wing. The KF was glued on with 2 part epoxy and there's no carbon rods anywhere on that plane.

I'm pretty confident I could upgrade to a more powerful drive set and run it on 3 cells and the wing wouldn't budge one bit even if I pulled the elevator all the way back out of a full speed dive with the pushrods all the way out on the servo arms.

In fact I think the only thing that can hurt this plane at all is a high speed impact or the LiPo going up in flames mid-flight.
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FeWOlf
Ok did a dry build full size, so issues I ran into, on the boon, had to cut of the the front boon top off, and cut the fuse support to the end to get it on, ran support foam strip about 1/4 in. in wide to support all connections, got a CoG at 5.24cm, ( 33%), 110 grams dry weight, will have to play with it , had to add weight to nose, and got a flew nice glide test of 15ft or so. Since I will be using twin motor, I should not have to add weight and will not really need a rudder, since this will be a slow flier, with directional thrust.
   Going to have to use to 2 layers of foam to strengthen the connection of Fuse and boons from wings, will be using a KFm2 for wing and cut a slot for the boons and fuse. Really don't think I will need to add support spars. Going to hold off on this project, since I have a few planes in build order before this one, plus it will give some time to sit back and look at what other mods I will need
Fly Like Hell, and you will get there!
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