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        Build Log "Crash-proof 3D foam RC plane" by hammydude12345

#1 potshot Dec 09, 2011 03:20 PM

"Crash-proof 3D foam RC plane" by hammydude12345
3 Attachment(s)
OK, it's not a build I've done yet, but I found this on YouTube. As is my habit whenever I run across an interesting plane I make AutoCAD drawings if none are available. I know no plane is fully crash-proof, but I loved the simplicity of this one, and I think it is probably quite a bit more crash tolerant than many others out there. It incorporates some good ideas. I will be building one some time soon, for sure. It's so straightforward it should be a quick build and looks like it flies well.

The build: http://www.youtube.com/v/wC6-ljrSpgA...yer_detailpage

Flight vid:
Crash-proof 3D foam RC plane flight (1 min 19 sec)

Hammydude12345 hasn't found his way to RC Groups yet, but I've encouraged him to do so. He confirmed that the drawings are accurate and asked me to post them. I hope you don't mind this indirect method, but I thought you might like to see this plane.

#2 F3Pflyer Dec 12, 2011 03:31 PM

All EPP I imagine? What motor Abd speed control?

#3 potshot Dec 12, 2011 05:24 PM

The specs are in the last 10 seconds of the build video. He says he used 3mm foam from BP Hobbies, but they only show 5mm on their website. The motor is a BM2408-12 with a 10x4.7 prop, with a 20A ESC and 1300 mAh battery (I'm guesing 3 cell).

I can't see why fanfold or Depron wouldn't work just as well. Built light, I'd imagine a Blue Wonder would be all right, too. That's the setup I'll use when I build mine.

#4 rewolff Dec 25, 2011 04:15 PM

I built it from 5mm Depron.

You guys manage to find materials that I can't get hold of... :-(

Anyway, I have a "too big" motor on there. I first had a smaller motor but it wouldn't run properly. Apparently I broke a ball in the ball bearing on the maiden of another project. :-(

Now I Have a 5" prop on this motor (C2409 from HK), which people claim should be run with 9" - 11" props. Will I be able to fly like this or do I have to make a larger prop fit? The plane+battery weighs 288g all up right now.

The advantage of the 5" prop is that it doesn't reach the ground, so I don't have to make a landing gear.... :-)

#5 potshot Dec 25, 2011 04:27 PM


Originally Posted by rewolff (Post 20230697)
Now I Have a 5" prop on this motor (C2409 from HK), which people claim should be run with 9" - 11" props. Will I be able to fly like this or do I have to make a larger prop fit?

A Hobby King search for "C2409" came up empty. The only 2409 motors I could find there are the bell types, which all call for 8 or 9 inch props. They are lower KV motors, so I don't think you'd get much out of them with a 5 incher.

Don't forget to post some pictures of your build, rewolff

#6 potshot Jul 12, 2012 04:08 PM

He's baaaaack
2 Attachment(s)
I finally got back to building one of these, and I've made some changes. I'm calling it Hammy26.

I cut the parts out of Hobby Lobby foamboard because I wanted to leave the paper on and want it to stay on. I scaled it down to a 26" wingspan so all the parts would more easily fit on a single 20"x30" sheet of foamboard, and that size plane seems ideal for my 1/2 acre flying space. The entire LE is a 3mm CF rod. This plane will be used outdoors so I hope the extra weight will be helpful in the wind.

I had lots of color packing tape so for once I decorated a plane before assembly. I still have to cut off the rudder and separate the fuse halves. The parts shown in the photos weigh 213 grams - porky by my usual standards but hopefully it will penetrate well if properly powered. I know it will not be a floater, and that's fine with me.

I haven't selected the motor yet; I want to see what the airframe weighs after assembly and with three 9g servos.

So far my investment is $2 for the sheet plus several feet of packing tape. I'm planning to use 5 min epoxy to assemble it. I have all the other odds and ends on hand.

#7 99CRASH99 Jul 16, 2012 10:44 AM

Hey Potshot,
Do you have plans for the Hammy 26?

#8 potshot Jul 16, 2012 11:58 PM

3 Attachment(s)
Here ya go, 99. During assembly I made some minor changes to the plans.The plans include those changes, the most important of which is the addition of 1 1/2" in overall length to allow more latitude for battery placement, which I could have used on mine. I also lowered the "canopy" top 1/2" and the top of the rudder about an inch in an attempt to cut some weight aft.

I mounted an Emax CF2822 with an EP8040 prop, 18A ESC, Orange receiver, 3 x 9g servos and a 3S 1300 battery. I'll have some photos of the finished product and a flight report soon.

#9 ausrod Jul 17, 2012 01:58 AM

Very Cool cant wait to build one! ill use depron and a emax 28-22 1534kv motor 15amp esc, 8x4 prop and 850mah 3sp battery. Thanks!

#10 potshot Jul 17, 2012 08:59 AM


Originally Posted by ausrod (Post 22185912)
Very Cool cant wait to build one! ill use depron and a emax 28-22 1534kv motor 15amp esc, 8x4 prop and 850mah 3sp battery. Thanks!

Great! Yours will be a lot lighter than mine so it will be a good comparison. Yours should be pretty lively with that motor. Don't forget to send pictures and a flight report when you're done, ausrod. Have fun!

#11 99CRASH99 Jul 18, 2012 08:22 AM

Potshot, Thank you for all your work on this it sure makes things easier on the rest of us.
It looks like you might have forgotten the notch in the rudder for the elevator clearance in your Hammy 26 plans.

#12 potshot Jul 18, 2012 11:01 AM

My pleasure, 99. CAD is one of the fun parts of this hobby.

Actually, if you look at the narrowest part of the elevator, you'll see that it fits entirely within the V-shaped area formed at the aft end of the upper and lower fuse halves. In most other builds you'd see a fan shape instead of the V shape. The whole idea behind this design is straight cuts, so it might be a little misleading.

#13 potshot Jul 18, 2012 08:48 PM

At last
3 Attachment(s)
Well, it's done and ready for maiden. It weighs in at 16 oz. on the button with a 3S 1300, at least twice as much as anything that size I've ever built. I said I wanted weight and I got it. Now I'll find out if it meets my goal.

The topside color scheme comes from a full scale Extra 300L that I got to fly a little bit recently. The Extra also had a purple component which I used on the bottom. I know it's not a candidate for Plane Beautiful, but I'm hoping it will be visible enough to these bad eyes.

Now to set up the TX for throws and rates. Hope to maiden it very soon. And despite hammydude's title, I'm under no illusion that it's crashproof.

#14 99CRASH99 Jul 19, 2012 07:17 AM

I see that you put your servos way up front. I made the mistake of putting them right behind the wing. That , as I found out, is a critical stress point because the whole tail section joins there. Putting the servos there weakened that area. On my 3rd attempt at flight it broke in half. (So much for Crash proof). I wish I had waited for your revised drawings because that tail heaviness is pretty bad. From your pictures it looks like your planes have the short nose? If so, did you have to add weight to the front?

#15 99CRASH99 Jul 19, 2012 07:24 AM

Oh BTW mine came in at 11oz. But I'm using a rimfire 250 and a 430ma 2s. I tried it with the tail slightly heavy and it just hovered on the prop.

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