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Old Feb 20, 2012, 06:33 PM
Ed @ Experimental Airlines
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United States, AZ, Phoenix
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Originally Posted by Mykro View Post
Thanks Hoppy..
I will try a test wing... Any ideas about installing a motors in the wing??
I vote for Hoppy's idea on washout and taper.

I have several twins and use metal motor mounts (described here
Foamboard Building Techniques: Metal Motor Mounts (8 min 23 sec)
), adhered with Scotch heavy duty foam mounting tape, stuck to a plastic gift card which is securely hot-glued to the exposed foam of the underside of the wing (cut out a small card-sized area). I have a small stash of titanium plate but aluminum barstock would work, just a little heavier. It's worked out very well so far, even up to the 6lb Skyvan I made recently, which carried 3 1/2 lbs of cargo. Nacelles do look cool, but I have never built them, just to keep simple.
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Old Feb 21, 2012, 11:47 AM
rcflyer
UK
Joined Jun 2010
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Quote:
Originally Posted by hoppy View Post
Depron is MUCH stiffer than $Tree foam and does not form anywhere as easily. I've tried many ways to form curved surfaces with Depron and none have worked really well.
Quote:
Originally Posted by ExperimentalAir View Post
The fuselage tubes can be made with Depron, with a little more difficulty. You must tape the outside radius of the bends, and I recommend taping the entire outer surface, overlapping generously, and pressing down hard with a credit card.

Make your marks for the fold intervals and then emboss the inside of the folds by scribing a small but blunt instrument into the Depron along a straightedge, something like a ballpoint pen with the ball retracted. Just enough to squish down the substance of the Depron about 40%.

Then make the folds under a heavy piece of wood or something like that. Be careful with the "overbending" to try to establish 90-degree bends as this may snap the Depron. It will be under somewhat more tension during the final gluing step, compared to Dollar Tree foamboard, and you'll likely need some jigs or helpers to keep the tube together while you apply the glue.

If successful you do get a nice, crisp 90-degree bend. The compressibility of Depron is not as good so the substance in the bend itself will kind of fatigue and come apart if subjected to a lot of chronic movement, but the tape should hold it together if properly applied.

If Depron is what you can get, give it a try. For us in the US it's tough to beat $1 per sheet of Dollar Tree foamboard.

Let us know if you have success so we can share with other Depron users.
Thanks,
Unfortunately here Depron is 2-3 times cheaper than foam board for a bigger bit!, I know it sounds crazy but yeah.. So I will give it a go at some point and let you know how it turns out!

Jim
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Old Feb 21, 2012, 12:45 PM
Space Coast USA
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OK,
So to add to Ed's comments....
The outside of the depron must be taped with overlapping pieces before bending.

I've used molds to form round body pieces, time consuming but works.
1 - Make a wood mold of the part you want.
2 - Cover outside of depron with tape.
3 - Heat wood plug in oven to 250F.
4 - Remove and press Depron over wood plug working it slowly around the part. As it heats it will form to the wood shape.
5 - When you can get the Depron all the way around the wood plug, wrap tape around the Depron and wood plug to hold it tight until the wood cools.

I've tried using a heat gun to soften the Depron but never could get it just right to where it would bend cleanly without melting and making a rough surface.

Others score the inside deeply with a fork to facilitate shaping it.

Much easier is to make a 4 sided box with an additional longitudinal piece glued into the corners of the box and then sand to get a nice rounded square.

Oh, don't forget that you can always use 3mm Depron over a 6mm frame. The 3mm bends much easier.

Good luck.
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Old Feb 21, 2012, 04:54 PM
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Just a quick teaser picture of a plane I've been working on for a few days now using Ed's techniques. It's a standard Armin wing and fuselage tube. The nose I just kinda free-handed, not 100% happy with it, but it works. There's still a lot left to do though! The main gear is just sitting there with rubber bands holding it on for the picture. Wing is just laying on top, there are no servos or control horns anywhere, no radio deck inside, motor mounts, etc. I do have the nose wheel steering set up though, with it's servo in place.

I'll start a thread on it once I get it a little closer to being finished, or maybe even wait until it's flown so the thread doesn't end with a total fail if it sucks! haha
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Old Feb 22, 2012, 07:39 AM
Ed @ Experimental Airlines
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Buddy, that's cool! I'm thinking CASA Aviocar-ish? Twins rock.
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Old Feb 22, 2012, 02:46 PM
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Thanks Ed! I was just kinda freehanding it, nothing in particular, but you're right it does look a lot like an Aviocar! haha Thanks for the tip! I'll study some pictures of that one when I start shaping the back and and placing the landing gear, etc. I might chop the nose off in front if the windows and reshape that too now, no promises yet though!
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Old Feb 22, 2012, 05:12 PM
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KeithLuneau you stole my design !!!! :-) (OK, so I'd stolen CASA and Shorts !!!). I bought some foam yesterday and had drawn out plans a week ago and then last night saw your plane - wow...

I was thinking of doing something like a twin "truck" and looking at the CASA C-212 Aviocar and Shorts Skyvan. I was going to finish the fuselage panels just behind the cockpit and use soft foam (have some lying around, not sure what type) and do the cockpit and rounded nose. Alternative do the same but from in front of the cockpit windows onwards in shaped foam.

Span 1 metre. Body 100 mm (height/width) square cross section. Wings centre section to just outboard of the motors and replaceable (changeable) outer wings. Aileron servos in the centre section.

Engine mounts a bit like the Skyvan with the ESC under each motor and in the airflow of the scoop.

Undercarriage - wheels against the body and partially faired in with over-cowl. Steerable front - ??? not sure yet but sensible.

Rear door openable for airdrops.
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Old Feb 23, 2012, 08:36 AM
Ed @ Experimental Airlines
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Mac50L, might I humbly offer my recommendation for the Skyvan as a great scale-ish foamboard plane. Easy to build and so good at its job. My most recent one is 1.5m wingspan, which has carried 1.5kg net payload, parachute dropped. My workhorse is actually this made up "RC-69" which is closer to the dimensions you describe. It wouldn't be hard to put an H-tail on there. The original Skyvan had suspension lines in lieu of struts.

My parachutes are scratchbuilt for like US$3 each from "jacket liner" nylon and tulle netting joined by hot glue - video forthcoming. I like using V-tail mixers for yaw control and ground steering (on grass at least).

Looking forward to seeing your creation!

Ed

SKYVAN Cargo Dropper (12 min 23 sec)


RC-69 Cargo Dropper - In Action (3 min 49 sec)


RC Short SC.7 Skyvan - cargo drops & crash (2 min 58 sec)
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Old Feb 23, 2012, 03:13 PM
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Originally Posted by ExperimentalAir View Post
Mac50L, might I humbly offer my recommendation for the Skyvan as a great scale-ish foamboard plane.
Looking forward to seeing your creation!

Ed
Just when I thought I had it sorted along comes another (better?) alternative, decisions, decisions...

At least the bending and fabrication videos have given alternative ideas to the way I originally thought of going about it. Only problem, our board has paper that hangs on like grim death so ways of working round that will need a little experimentation.

Now a problem - has the wind dropped so must go flying or should I pick up a sharp knife... or a cup of coffee and think about it...
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Old Feb 24, 2012, 02:29 AM
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So far - the board with the non-removable paper (doesn't peel at all). Cut through the paper along the boundaries of the area to be removed. Sand off the shiny surface in that area. Cut tissue/Handitowel/paper towel slightly smaller than the width of the area and spray with label remover. Lay on the sanded paper. Wait. Give it a few minutes and then carefully peel.

Label Remover - from Radiospares, #236-1874, Electrolube ERLRM200DB, $15.20NZ. I presume there are other suppliers but Radiospares is international. Advantage over things like fuelite and other camping stove fuels is it smells OK (lemon) and shouldn't be as nasty to handle. Note "shouldn't", thats not to say I'd drink it.

It might seep under the area not to be removed but as long as the edges are cut so only the part you want to remove is peeled off, after the seepage dries the paper should have restuck as well as it was originally.
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Old Feb 24, 2012, 06:11 AM
Ed @ Experimental Airlines
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Mac50L,
We in the US have this fortunate paradox where the cheapest foamboard is also the best for this particular method. The paper is thin and unattractive, but also peels very easily. The challenge is finding this kind of stuff for our friends in other places. I am completely ignorant to the situation in NZ, have heard "Riot Art" in Australia has some, but don't know if they have outlets near you. This company 3A composites implies their Kapa-line foamboard might be available to you http://www.display.3acomposites.com/9.html?&L=1 It pains me to think of all the trouble you are going through to get the paper off the foamboard. Keep looking for that cheap stuff and stay in touch. Ed
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Old Feb 24, 2012, 09:54 AM
FPV FTW
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United States, TX, Brenham
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Hey Ed,

My friend Keith pointed me to this thread, I had previously only been lurking in your thread over on fpvlab. I've watched all your videos countless times and started to build my own cargo plane right around the same time Keith started his. I am building two other planes at the moment, but your method of building with the dollar tree foamboard and tape has made it hard to work on anything else.

10mm sticks are going to be glued to the underside of the wings to allow for the use of slow stick motor mounts. Also, I think instead of a battery hatch like yours has, I'm going to hinge the entire nose of the plane for easy access to the avionics and battery compartment.

Here's a pic of mine so far, since the picture was taken, all surfaces have the servos installed and I'm hoping to finish her up tonight and hopefully maiden on Saturday.

-Pat
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Old Feb 24, 2012, 08:55 PM
Ed @ Experimental Airlines
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Pat, that looks awesome! The all-black is badass, you're sure to get some compliments on that. Yeah, do it up how you like it, let us know any discoveries you make. Happy flying on Saturday. Hopefully a video? - Ed
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Old Feb 24, 2012, 10:30 PM
FPV FTW
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Thanks Ed! I will definitely be making a video of the maiden, but I ran into another hurdle...didn't realize I was out of XT60's lol. Now I'll have to wait to maiden until I can get a hold of another one.

Here are a couple more shots of it in it's current state as of tonight.

The landing gear struts were fabricated out of a $4 piece of 1/16x3/4" aluminum flat stock and some 4-40 screws, nuts, and washers. There is also a strut for the wings, but I may not even use that.

The motors and esc's were salvaged from a tricopter I crashed, so as of right now...the most expensive new part on the plane is the $7.30 pair of 3" dubro wheels.
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Old Feb 25, 2012, 05:29 PM
Ed @ Experimental Airlines
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United States, AZ, Phoenix
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That nose design is really smart. You can access the batteries and the forward cargo deck too. I can attest that this is a big advantage that I'll build into future medium sized cargo planes. The gear struts get the belly out of the grass. I like it!
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