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Old Jul 13, 2011, 09:57 PM
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vtdiy's Avatar
Southern Vermont
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Well, I built a second P-40 to replace the last one. This time reinforced with tape in the forward fuselage and center wing area.

I swore I wasn't going to paint it this time before the maiden, but I ended up doing it anyway. Oh well.

AUW is 9 oz.

specs:

TP 2408-21 (BP-21) motor,
8-4 three blade prop cut down to 7" dia.
9G servos,
800 mah 2S Blue lipo
18a Turnigy plush ESC
OrangeRx 6ch

I've got all the settings on the TX from my last good (nearly) test flight. CG @ 44mm. Everything checks out. Ready to go.
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Old Jul 13, 2011, 10:22 PM
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Canada
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Wowee that looks spectacular!!!!

Can't wait to see the maiden!

How did you paint it so well? What kind of paint did you use?

Is the OrangeRx supposed to be full range? What do you think of the AR6100e target hobby is selling for $3.99 each?
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Old Jul 13, 2011, 11:15 PM
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vtdiy's Avatar
Southern Vermont
Joined Feb 2007
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astronaut, I sanded all packing tape lightly with 220 grit paper.

Then I used Craftsmart brand paint (cheap flat water based acrylic) that I picked up at Michael's craft store for $ 0.77/bottle when it was on sale last Spring.

I had an old badger airbrush that I cleaned the gunk out of. I mixed the paint with some water to thin it and a squirt of Windex window cleaner. Set pressure to 30 psi.

For shaping the camo, I just took some heavy paper (cardstock) and ripped it into shapes. Used that as a mask held slightly above the surface I was painting.

That is MUCH easier to do if you paint the parts flat before you assemble the plane. I did that on the first one, but not on the second, because, uhhh.... I swore I wasn't going to paint it before the maiden.

So the second one has a few sags, and finger wiped drips, but hey, it's camo. As soon as you put the insignia on it all looks good.

The insignia I made up in Open Office Draw (free program). Then printed on paper. Covered paper with packing tape and then cut out insignia with scissors. Coated the back with 3M-77 adhesive, and stuck onto the plane. Note: the 3m doesn't seem to work as well as usual on top of flat acrylics I guess. I had to re-stick some edges down. Might try something else next time.

Oh, I didn't make the canopy graphics -- that was found earlier in the this thread -- but I did modify it to more closely match the camo base color. Also didn't do the shark's mouth -- found elsewhere on the net, unattributed.

**********************

Lesee, you asked about OrangeRX full range -- uh no, it's supposed to be a parkflyer.

Personally I only need about 15 feet of range anyway.

Don't know about the 6100E from Target hobby for 3.99. Might look into it.

Here's a pdf of the insignia I used. Couldn't figure out how to put skinny letters across the fuselage side webs, so I skipped them and just did the roundel. Apologies to British pilots.
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Old Jul 14, 2011, 10:19 AM
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Wow that's a pretty nice description of how you painted it. I desperately want an airbrush system, but the compressors are just too expensive for me right now. Do you have any ideas on what I can do to get that system cheap?

I use a paint brush and heavy acrylic paint, which is not good for the planes in terms of added mass.

I think you should look into the $3.99 RXs. I know you can't fly at only 15 ft lol, but these are supposedly good up to 1500 ft. They are lighter and cheaper. I want to buy some soon. You can find a long thread on it in the hot deals section.

Keep me posted! Can't wait to finish my plane, just swamped with other work right now!
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Old Jul 14, 2011, 01:02 PM
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vtdiy's Avatar
Southern Vermont
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I think I've heard of people using a truck or tractor tube with a bicycle foot air pump for an air supply for an air brush. Might check out a tire dealer for these in case they have an old one you can patch.

I once tried a new (not used for any chemicals) hand pump-up garden sprayer, but it was too small capacity to power an air brush for more than a few seconds without having to stop and pump up again.

I think for camo it should be possible to dab it on with a sponge and stencil and get a similar effect. Don't try to get get opaque coverage first time, rather put on very lightly and let dry quickly (same for airbrushing) then go over it two or three times. This makes the lightest weight and best looking coverage without drips. There are also special foam or bristle dabbing brushes made for craft stencils that might work well.
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Old Jul 14, 2011, 03:18 PM
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Hmm...well I have a bicycle pump. You think that would work? I'm always on the look out for a cheap compressor at garage sales.

The bicycle pump seems unlikely to work to me though, maybe I'm wrong. And how would I pump and paint at the same time? I guess I could get someone to help lol

Ah, the things I do for this hobby.

Thanks!

BTW, also wondering why you mixed windex in the paint. Thanks!
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Old Jul 14, 2011, 09:48 PM
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Southern Vermont
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Astronaut, the reservoir (truck tire) means you don't have to constantly pump.
Same thing for a pump up garden sprayer. The bigger the reservoir the less often you have to pump. It's not ideal, but if you're a DIY type it's do-able, and a matter of exercise. You're not painting a car, just a small model.

Windex helps the acrylic paint flow through the air brush and also not bead up on plastic, like packing tape. (Although, you should scuff up tape with 220 sandpaper before painting anyway.)

It's possible to make an air compressor largely from recycled stuff, plenty of references all over the internet for that, but it can be dangerous if you don't build or equip it properly. A tire and foot pump is more sensible, I think, if cash is thin.

Now it would be interesting to build a simple homemade airbrush, itself. Those aren't cheap, unless you already own one. But not extremely complicated, I wouldn't think, for purposes of simply painting a model.
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Old Jul 15, 2011, 01:17 PM
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Ohh I didn't know what a truck tire was, i.e. the reservoir. Hmm..hopefully someday I can find an affordable setup.

Check out the pics. This is the setup I am working on right now. The plane is glued together, and the gearbox/Rx are installed the way you see it.

The problem is the way the Rx is exposed. Can you think of some way I can protect it? This is precisely why I don't like these too much, I can't wait to move to separate components, rotary servos, and BL motors! Hopefully soon!

I'll have to be very gentle with this plane since all the parts are so exposed. Even the gearbox

One more thing. The motor seems to pulse when I run it. I mean, it runs constantly, but for some reason it makes a pulsing noise, perhaps it's slowing down not stopping at every pulse. Quite odd. When I use my Hyperion instead of the stock 150mah battery, it doesn't pulse as evidently, but still does a little.
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Old Jul 16, 2011, 11:45 PM
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Build a little foam box around it.

Maiden of P-40 went very well. Had a rough landing that did a little nose bending and loosened the motor mount clamp, didn't have a metric allen wrench so couldn't fly again without going home. Everything is fixed up,hoping to fly tomorrow afternoon.

Plane flies very neutral. Whatever you do, there it is, in that position, instantly. Not quite as fast as I'd imagined, though fast enough -- but perhaps it's the throttle limit I set -- have to check. Anyway looking forward to flying again.
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Old Jul 17, 2011, 08:17 AM
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Hmm alright, but how will that affect my flight characteristics?

Great to hear your flight went well! My nose area keeps snapping off, but I think it just got weakened because of one hard nose dive. I'll figure something out for it. Mine doesn't fly like yours though.

I think I need to get used to it a little more. I think it also needs absolutely zero wind. It seems to be balanced properly, just trimming. There is WAY too much throw, I really need a programmable Tx.
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Old Jul 17, 2011, 03:36 PM
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Southern Vermont
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Actually you are having all of the same reactions that I did. Except the need for no wind -- which makes sense since your plane is so light and has more lift with the camber, etc.

Like yours, mine had WAY too much control throw also -- I ended up setting the throw limits to 35% on the transmitter. Any way you can lengthen your control horns? I know with your linear type servo you can't shorten the servo throws like you can on rotary arm servos.

(Guess that single aileron of yours was plenty sufficient, btw. Yes?)

Also, mine crunched up the nose on a regular basis, too. It's been much better since I taped my forward fuselage pieces on all sides before assembly.

One way you could get lower control response might be to use a half elevator (yes that has been done many times before). Just cut the connection between the two elevator halves and tape a splint under the stationary half to keep it flat. A flat toothpick would work.

And cut down the single aileron in size, too. Same way.

You can always restore them later if you want by removing the tape and splints, and gluing the control pieces back together.
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Old Jul 17, 2011, 04:24 PM
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Flew mine today and it flew great, even though we had some gusty winds. I did a couple loops and rolls and the plane was responsive. Flew for about five minutes. I was doing a roll when a gust hit and the wings both folded down against the fuselage.

She came straight down with the wings still attached but trailing toward the tail.

When I got it back I found the wings had flexed downwards to break (not up) and the break was clean along the wing shoulder reinforcement web. Perfect example of a stress riser break. (See photo). I wasn't doing an outside loop, but the roll in combination with a wing gust did the job.

It sesms clear that these single sheet flat wings need tape spar reinforcement not only on the bottom of the wing, but on top. I used two side by side strips of 3/4" fiberglass packing tape on the bottom, but none on the top. I also put clear packing tape on the top and bottom of the wings extending about 2/3 the way out to the wing tips.

However, I forgot to do this until after I attached the wing saddle web on the top. So I had to butt the tape to the web -- it didn't travel up across the web, and didnt extend under the web across the centerline of the wing.

What I should have done was to glue the two wing halves together, then run fiberglass packing tape strips from wing tip to wing tip on both the top and the bottom of the wing. Than added the clear packing tape skins (top and bottom) out 2/3 to the wing tips. Then, and only then, glue on the wing saddle web over the tape.

Well there is not much I can do to fix this plane, despite the clean breaks in the wings. They will always fold again along that line. I'd have to build a new one. Not sure I want to build a third one just to prove the construction out. I did fly it, and was confident in that, so I may move on.

I don't really like this kind of sheet construction for a high powered plane, since they actually seem kind of fragile compared with solid construction. Without landing gear, the sharp corner of the lower nose section catches in anything but a perfect landing, and the 5mm foam just doesn't have much resistance to bending or snapping, edge on.

Repairs leave this kind of construction weak, unlike solid foam with some thickness.

I may do a similar warbird next that has a solid fuselage and cut core wing. That kind of construction is tougher, I think, and more easily repaired.

I do like the size of these planes and the feel, so maybe it will be similar in most ways, just a different construction method.

EDIT: I should add that the original Scotta (Electric Orange) plans call for a carbon fiber tube spar. And that might be fine for adequate wing stiffness. I went with tape spar because of earlier comments in this thread by Irone who designed many similar combat models which used tape spars:

http://www.rcgroups.com/forums/showp...3&postcount=90

-- also Irone's combat faomie thread -- see posts #369 - on for construction techniques:

http://www.rcgroups.com/forums/showt...303127&page=25

I don't have access to a local source for carbon fiber, and don't really like to use it, anyway.
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Old Jul 18, 2011, 04:38 PM
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Canada
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Well, I will try to fly it again tomorrow, and see what is causing the issues. I could put something there to limit the travel, but the problem is I have to be way too precise on the sticks since I need to make really small movements to get the desired travel. I will increase the length of the control horns.

---

ACK! That plane looks like it really came back from war! Wish you had a video of the plane flying. 5mm seems too thin for this profile type design. 5mm seems too thin for my micro plane too. But then again, I'm using a different type of foam.

Have you tried to build the Funder and Lighting? Looks kind of cool, and may be something I would build next once I get this working.

So far I want to build the BYOB and Funder and Lightning after this.

Let's see.

Please keep me posted on your work. I will try to fly my P-51 again tomorrow, really bad weather this morning. Been tremendously hot here recently, over 95F...
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Old Jul 18, 2011, 08:38 PM
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vtdiy's Avatar
Southern Vermont
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hey astronaut, I will keep you posted. I get half tempted to build another one, after the irritation wears off. Usually right after a crash I'm willing to give up on it, but a day or two later, I start thinking about it again. Since I made patterns of all the parts, it's only about a half hour's work to cut out another one.

I just hate all the fiddling -- installing tape, surfaces, gear, motor, battery, balancing, etc. Which seems to take a few full nights of work, even if I strip an old one.

I think your plane will be fine, strength wise because of much lighter weight. 2G's at 9 oz is 18 oz. 2G's at 3 oz is 6 oz. That's 12 oz less stress. Also yours will fly at lower speeds, and you probably won't fly in gusty wind like I did. Or shouldn't.

Yes, you really need to cut down on that control sensitivity.
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Old Jul 19, 2011, 06:16 PM
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Thanks!

Ya I know what you mean, the grunt work doing all that stuff is the hard part. Takes a long time. Putting the foam pieces together could be done in 45 minutes. I still haven't got a chance to fly it again, hopefully tomorrow morning.

Cheers!
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