LlamaFragments

Hello!

First post. LlamaFragments is just a general online alias, like Espresso-Outfitters.

I have been hovering around for awhile and decided to register.

I have started building FoamFlyer's Airplane! I have gotten all of the materials that I need, and today I made a slightly different type of hot-wire bow.
This will be the first airplane that I own, but I have flown other people's airplanes numerous times and have spent a significant amount of time on the RealFlight simulator.
Either way, I attached a picture of the bow and the power adapter that I used. It's a sony dc 16v 4a power adapter for a battery charger and I'm using 28 gauge wire that's from Home Depot.

Fisher

LlamaFragments,

Welcome aboard! Your home brew foam cutter looks like a nice lowtech solution. Have you had a chance to cut much foam with it? Seems like you might have a little trouble keeping the wire tight enough but you will know real quick if that it the case. 4 amps seems a bit low too but like I said you will know real quick like if either of these things is an issue.

Cheers,

Fisher

critterhunter

Did the most flying I've done in a long time yesterday. Came with two planes (My streamlined Stryker...AKA Streaker, and the Dual Boomer) and went home with two, so that was a plus.

I got one flight out of Streaker and no problems. Didn't do too much stunting with it because, even though it's flown about twenty times, I was busy fine tuning trim and dual rates. Since it's built like a brick it should be around a LONG time. There, now I've hexed myself.

I slapped some servo extension plugs on the dual boomer with tape and lopped off some nose so it could maiden, though it still needs more work. It took off without a problem and I ran about five or six packs through it. The plane was using a BP21 re-winded down to (I think) 1100 or 1200 k/v. I didn't want this plane to be a speed demon since it's supposed to be a tank in the air along the lines of the Wart Hog. Also wanted to keep the amps down to 10 to 13 in case my older Comon Sense packs were getting weak. Good news is they are still running strong.

I played with an APC E 8x4, 7x6SF, and a 7x6 gas prop on it. All of them were a little slower than the speed I want, so I may do a re-wind of the motor with just a little more k/v or try yet another prop. Before deciding to do that I want to fine tune and streamline the bird more to see how it acts. Right now it's lousy at loops (COG, drag/speed, and too long of a nose issue) but rolls aren't that bad. Not going to be a trick plane but I know it's capable of more like build #2 and 3 were. Haven't installed the streamlined cowl over the motor on top of the wing or lopped off enough nose yet, along with a few other things that are causing heavy drag right now.

On a final note, the 15C Loong Max 2250ma packs we are using from United Hobbies are doing well thus far but the proof will be after 30 or so cycles. I was using the 15C 2250ma 3 cell yesterday. It's very light, already has the deans soldered on, and as an added bonus they give you the ESC male plug. These packs are only around $18. The 20C packs are about $24. If they don't puff or lose capacity they'll be a great value. So far my blue HXT 20C 2250ma 3 cell pack is also doing well with no puffing. My Hi-Model pack has puffed and no longer can deliver the amps needed. With only about 40 or so flights on it I'd say stay away from them. They are more expensive anyway.

LlamaFragments

Fisher,

It cuts foam reasonably well. The thing with the tension on it is that you just have to over-tighten it to begin with, and then it will be at a reasonable tension to cut with. For some reason we couldn't find a single spring in Home Depot...
Tonight I'm going to cut out the rest of the template I was working on and maybe start cutting the wing.

LlamaFragments

I got the templates done...

But my bow sucks. It does not give enough tension. I tried using a spring but that just broke the wire. Ended up going through 3 7x36 sheets that all were destroyed[:@]

Does anyone have any tips on how to cut the wing with a bow? I obviously failed. Just general techniques that work with a good bow.

critterhunter

Single springs can be found in the screen door section and work well, or they might be near the other spring area. That's somewhere around the nuts and bolts area but usually off to one of those small cut across rows.

critterhunter

I'd check page one of this thread. I covered the "I" style bows. About as simplistic as it gets. I used a screen door spring to pivot tension on one end of the "I". Pictures and instructions on page one will make it clear. I'm using stainless steel .022 gauge fishing leader (or is that .022 diameter?). I hear .024 works well too with my friend's 40" as well. We both power ours using a $30 Harbor Tool and Frieght battery charger (pic on page 1) in the "starting" and "55 amp" modes. No need for a dimmer with that setting, this gauge wire, and that charger. Any other questions just ask.

critterhunter

Forgot to mention about the BP21 re-wind on build #4. The "stock" BP21 wind works great for the plane. I normaly ran an APC 8x4E (about 12 or 13 amps) on it, while I think Fisher runs a 7x4 or 7x5E (probably 10 to 12 amps). The 7x6SF prop (14 to 16 amps or so) would also probably be killer, giving the plane tons of speed (I know it did on my Stryker). A stock BP21 is about 1760 k/v or somewhere around there. I have this one winded to about 1100 or 1200 k/v. Not because the torque wasn't good enough on the prior three builds, but because I wanted to keep the amp draw as low as possible for my older Comon Sense packs by trading off a little speed but also gaining a little torque in the process.

The 8x4E was noticably slower on this wind than the stock one. Too slow, but as I said it might be due to the streamlining and other issues I still need to fix. As the speed gets slower you've got less air flow over the controls, so even though this build has two ailerons it didn't roll any better than the prior three builds with only one. Same with elevator. I had them both maxed to 125%. I'm sure they'll get really responsive once I pick up a little more speed. Keep that in mind...if you are using a faster motor your control surfaces can be smaller and vise versa if you want. I tend to just oversize them and then lower the rates or throw to compensate.

Forgot to mention, I had concerns about the rudder size. Good news is it had pretty good response, even at the low speeds it was doing.

LlamaFragments

Okay, I figured out a solution to my problems. What I'll do is make two wings, each 17 1/4" long and then attach them with a carbon fiber rod that goes through a bump on the fuselage. I then tape between the bump and the wing. What this does is it gives me a smaller piece of foam to work with, and makes the airplane more portable. This has probably already been done before...

Either way, I found a spring for my bow that works! [X(]....

critterhunter

Can you describe your carbon tube method more clearly so I can understand what you are doing? I've joined two wing halves for a 6' version of the So plane before by using two aluminum arrow shafts with a nylon rod sliding into them, but carbon fiber is better, using a smaller tube sliding into a larger one.

LlamaFragments

It'll have two carbon fiber pieces that are inside of the fuselage that go into the wing. Then tape prevents them from sliding in and out.

Okay, I actually cut the wing parts well! Cool!

By the way, here's a picture that is resized so that it has a 7" chord length. Taken from CompuFoil.

critterhunter

Good job on cutting out the wing! And I see now what you are doing with the wing. Should work fine.

calvino

ooh, is that the airfoil?????, guess it is, sweet[8D]

Fisher

LlamaFragments,

Good call getting a hold of CompuFoil. Makes things a lot easier.

Hope you find a good setup on the foam cutter. You just have to keep trying different combinations until one works for you.

Glad you are making progress.

LlamaFragments

Yeah, thanks. School is so annoying... I keep thinking WHY AM I NOT AT HOME MESSING WITH FOAM? (could make a song about that)
So I try to do it whenever I get the chance which is not very often.
Here's a picture of one of my wings.

calvino

oh, lookin good, ya, that would be a funny song, you can put it to a photo log vid/maden of ya Soo

critterhunter

Wing looks good. I noticed a bit of a "ripple" in it. It's no big deal to sand that right out. But, that is normaly caused by either too cold a wire or rushing the cut too fast. It can also be caused by not enough tension on the wire, but that can be compensated for by going slower with the cut so it doesn't drag. You'll get it. I had to cut several wings and tweak things before I could get it just right (without the need to do any sanding, which is no big deal).

By the way, a tip for wing templates: A friend used that metal duct tape from Home Depot to cover his wood airfoil jigs. He said it makes the wire slide nice and smooth. I've also heard that a strip of wire epoxied to the top of the airfoil jig also does a good job. I've never covered my wood jigs with anything. So long as they are smooth (round off the top corners to prevent drag as well) and your wire is hot enough it shouldn't do any skipping, which can also cause the "wave" pattern.

One more thing. I'm now hooked on this really strong and dense EPS foam a friend and I are getting for free. Sure, it's a bit heavier but you'll save some weight on not needing certain strength mods. It also breaks very clean with no chunking, much like Stryker foam but even better. I've got enough of this stuff stored in my garage attic to build a real sized plane. Anyway, I believe this stuff is called "Falcon Foam" as that's what I found stamped on the side of one sheet. I know you can't find it at Home Depot or Lowes, but I bet it could be found at remodeling supply centers that the contractors go to. Lay your hands on some of this stuff if you can. You won't believe how strong, smooth, and stiff it is.

LlamaFragments

Thanks. The ripple is probably caused by rushing; a reaction from failures of going too slow. The wire cutter (current edition) is hot enough to melt the foam without completely touching it, but not enough for it to glow at all.

Umm, I was looking at different parts for the plane. Does anyone know anything about the Towerpro motors at United Hobbies/Hobby city? They look almost exactly the same as BP-21's and have the same statistics. And those Loooooooooooooooooooong () max look pretty promising.

I did some research on Falcon Foam, they make insulation foam like the InsulFoam that FoamFlyer suggests. They were bought by "Atlas Roofing" who make (who coulda guessed it) roofing products. It looks like the only way to get it is to be a contractor and order it directly from the manufacturer.






(did anyone notice that I'm into parentheses?)[X(]

LlamaFragments

Alright, I have a very rough fuselage now and both wings. Took like 4-5 tries to get that second wing done right. Wire kept breaking.
So the pics have the fuselage with the carbon fiber/tape wing attachment.

critterhunter

The 2408-21 is called the BP21 by most people, as Balsa Products was one of the first to carry it and that was the stock #, I believe. A "T" or "D" version will work, though the "D" is built better but has the same stats. Some places don't offer a "D" version, and so most comon is what people call the "T" (A more pronouced "mushroom" looking motor, where the "D" is more squashed down in looks).

Just did some research and found out the Loong Max packs don't hold up the voltage under load as well as the HXT packs, but the Loong Max packs do have a more "true" capacity raiting than them and even many of the expensive brand names. Some guy put several company's packs through some extensive testing. I'd use the Loong Max for instances where heavy amp draw isn't going to be a concern if that results in lower voltage and thus less speed in a high speed platform, or in a low speed platform where the spacers in the pack will help keep it cool. Use the HXT pack where you want top performance under max amp load (like no drop in speed on a high speed bird). The Loong Max don't suffer from the bloating reputation that the HXT packs got after that bad batch that went out last year, but I have yet to have my HXT pack bloat. It's a tough choice at the moment as to which pack I'll buy next. I'm guessing I'll get another HXT pack because it's critical for the speed platform (EDF) I'm building to keep the voltage high under heavy load. Every little bit of extra speed counts as I'm entering in a local speed competition.

critterhunter

Very good job! I see you are using the EPS white foam that Foam Flyer showed pictures of. My local Home Depot doesn't have this stuff with the covering on it, just bare EPS white foam up to 2" thick. Of course I'm using this Falcon Foam stuff now so I pitched out the other stuff. It's THAT great. I wouldn't touch the old stuff with a ten foot pole now. Also check into the pink or blue (blue is better) at Home Depot or Lowes. Stiffer than the white they sell and smoother, but also seems a little more brittle. If I had to go back to them for my foam I'd probably opt for either one of those these days.

critterhunter

Saucerguy, your build looks good but post it over here and not in the old thread so we can gawk at it and remark.

LlamaFragments

Thanks. I ordered the rest of the stuff that I needed, IE radio/servos/motor/battery/charger. I got the TowerPro 21T motor and the 2250 3s 20c Loong Max li-po from HobbyCity, and I got the other stuff from Tower Hobbies. They didn't have a very good selection of radios at HC. Later today I hope to get the booms and stabs cut.

critterhunter

Here's a great link to some testing of both the "T" and "D" versions of the 2408-21 (BP21), 2409-12 (12T), and 2409-18, all of which are some of my favorite motors for price. Not very efficient motors but the 18 isn't all that bad and it's a great low RPM/high torque motor for slower builds or even 3D. The 12T is a nice combination of both speed and torque, sort'a motor that's got it all...real good speed but the ability to be a torque monster for unlimited V. Think of the BP21 as a little brother to the 12T, perfect for planes under 20 or so. Againl, the "D" versions are the same specs but just built much better. Get those if you can.

This page and the following one have reviews of various "T and D" versions.

http://myhobbycity.com/showthread.php?t=345&page=2

calvino

er, considerin makin one (like I don't have enough airplanes to make........) can you take thinnner foam, aka, .5" stuff, and glue 3 sheets together, or are you better off with one 1.5" sheet, my dad had that idea after seein it at Home Depot, ah, also, is it critical to remove the plastic stuff on it, lookin good lama fragments