Foam Kit Building
 

Hey Guys, Im relatively new to foam combat aircraft building. As of late, my interest has grown and I would like to start building a foam fleet (2105 or 2610) of aircraft without having to buy a bunch of kits. After doing a little research, I have semi-concluded that I would like to attempt to build my own foam fleet from scratch using a hot wire cutter and the whole nine yards. As mentioned previously, I am 100% new to foam aircraft building and do not have any experience or the equipment required to start this process. If possible would any of you guys know of a couple good books or websites to get me started with everything I will need from building a hot wire cutter, to aquiring the right type of foam, and finally to building and shaping the specific aircraft parts. I'd appriciate all the help I can get, with all the experience already out there, it doesn't sound too unfeasable. Thanks for your time and help

RE: Foam Kit Building
 

Wow! That's a tall order!

Forget about 2105 because no one has been flying that class. The bigger engines in 2610 make the planes launch easier and fly better. Another class of scale combat known at 2548 is on the horizon, and may be worth your while to check out:
http://www.rccombat.com/forum/forum.asp?FORUM_ID=34

For the most durable scale construction techniques, study this site:
http://www.jkaerotech.com

More specifically, this page:
http://www.jkaerotech.com/FWTA152bs.htm

An important variation on their techniques for more strength is covering the airframe with a low-temp iron-on film. Be sure to mist spay adhesive on the foam parts before covering.

Opinions vary on airfoils. My personal favorite is the E205:
http://www.ae.uiuc.edu/m-selig/ads/afplots/e205.gif

Coroplast for the tail feathers (4mm) and fuselage 'doublers' (2mm) can be bought in a variety of colors from Harbor Sales:
http://www.harborsales.net/fullsheet...=Foam%20Boards

"Plazamate" blue foam by Dow is the best for wings because it is rated at 60psi crush strength. It is normally used for under freezer floors and under sidewalk pavers.

Regular pink or blue foam insulation will work fine for fuselages, and is a both a little lighter and a lot cheaper than the Plazamate. Check your local builder's supply houses for both of those.

TONS of good info on cutting foam parts can be found on this thread (unfortunately for an electric, but most of the info still applies):
http://www.rccombat.com/forum/topic.asp?TOPIC_ID=11510

Some more information:
http://www.spacemodeling.org/new/how_to/Foam_Cutter.htm
http://www.rccombat.com/forum/topic.asp?TOPIC_ID=11049
http://www.techlib.com/hobby/hotwire_foam_cutter.htm
http://www.charlesriverrc.org/articl...gmancutter.htm
http://www.hhhh.org/~joeboy/resource...am_cutter.html

HTH,
D

RE: Foam Kit Building
 

Hey Demon, thanks for the fast a very thorough reply. Judging by the number as well as detailed posts you have replied to in these different combat threads, it is quite apparent that you are the local expert. After reading through the different websites you recommended above, Im kinda in a toss up between starting my own scratch fleet as previously mentioned or maybe investing in a few JK Aerotech birds. I was very impressed with their website which contained some neat birds, and they seem to be quite reasonable with their pricing as well. What would you recommend? I have built serveral PICA warbirds, all good flyers but all relatively heavy and therefore lacking the competitive edge thus influencing my decision to possibly start up a foam fleet. I guess right now, I have the luxury of going either direction and I am not sure which decision might be better. Do you scractch build your own or are you a kit man? I am impartial to both, what would you do? Thanks again for your time, it is appriciated

RE: Foam Kit Building
 

"Local expert"? Me? Given the high level of talent that participates on this board, I don't know about all that. But thanks for the compliment! ;)

I would recommend buying a few JK Aerotech kits first. Once you see what they have to offer, you can either buy more kits or custom-cut your own. Of their kits, I highly recommend the P-47. It is very competitive if built as the long-span Bubble-top P-47N.

Remember to build it exactly as they show, but cover the foam parts with a low-temp iron-on covering instead of the supplied packing tape. Mist a light coat of spray adhesive on the parts to help the covering stick. Another great upgrade is to replace the kit's spruce spars with 1/8" fiberglass rods. The rods are available here:
http://www.intothewind.com/shop/Repa...ods/1-8_FG_Rod

I have built several of JK Aerotech's kits, but I cut my own kits too. The real deciding factor is subject matter. If no kit exists of the plane I want to build, I just cut it myself.

Good luck! And, keep us posted on your progress!
D

RE: Foam Kit Building
 

One more thing...

It is extremely important in R/C Combat to be consistant. This means several of the same plane with the same engines running the same props in each and all of them set up the same.

How many is "several"? About 3 is enough for a whole season of 6 or 7 contests, each featuring 5 or 6 rounds. If more rounds are flown in a single day, you might want to add more planes to your fleet. Now, this number is based on the fact that I absolutely despise making repairs between rounds - I don't even like to change props. If something happens to a plane, simply set it aside and grab another. Less stress and more fun that way.

D

RE: Foam Kit Building
 

Don't let Demon fool you, it takes effort to kick his butt :D.

Seriously though, that's some great advice there. I agree with just about everything he said.

My first scale combat planes were JKA P-47Ns, and while they aren't as fast as what I'm flying now, they really do fly well. They have a TON of wing area, and that's key.

That kit is also one of the few that is legal in both 2610 and 2548, which makes it even more appealing. Right now it's a toss up as to which class will be more popular next year, I suspect it will vary a lot depending on where you live and who you fly against.

And Demon is exactly right that to be competitive, you really need 3 or more planes that basically fly the same. Fwiw, I took 5 of my plane to Nats this year, and it made a huge differnece over prior years when I wasn't as prepared.

However, you don't have to build and equip them all at once. Wings break more often than fuses, so going with 1-2 fuses and 3-4 wings is better than 2 complete planes. I've also gone as far as to build 2 airplanes, equip and test fly one, then pull the engine and radio, put it in the second, and test fly that. Get both models saved in the radio. At the field, an engine and RX swap doesn't take that long. Not as good as having multiple planes and not having to repair, but better than being a spectator.

(oh, the one thing I slightly disagree with. I've found that while heat shrink is strong, it doesn't take damage well. I use packing tape instead these days. The tape can be shrunk a little, and if applied well gives almost as much strength as ultrakote or other coverings. The differneces is when you get hit or take a prop cut. The heat shrink coverings tend to rupture and loose all strenth. A tear will travel all the way accross the wing and the result can be a dramatic wing failure. With tape, you put it on in 2" wide strips that overlap. The overlaps provide a natural "rip stop" effect, so tears don't travel accross the entire wing or fuse, so the failure is less dramatic. And tape can be easily field-patched with more tape.)

RE: Foam Kit Building
 

Demon and Montague, thanks again for the replies, I have a couple of questions though for each of you. First about the JK Aerotech kits. Its sounds that you both are partial to the P-47, its sweet plane for sure. How about the other JKA kits, I personally love the Corsair and wouldnt mind getting a few of those. I know they habitually never perform as well due to the wing dihedral, so what about something like the Zero? They claim it is a straight forward kit to build and flies very nicely. Once again, Im think im in a toss up.

Secondly, Demon I was really excited to hear that you could cover the aircraft with something like monokote or coverite instread of tape. I didnt like the idea so much of covering the plane with packing tape since I try and take a little pride in making my planes look good. Montague however didnt reallly support the idea as much claiming that a lot of the strength is compimised. I kinda agree with him because Im sure all that tape does a good job strengthening and preventing tears.

What about sheeting the wing? Do you guys think the aircraft would take a pretty big weight hit or would it be worth it to help with the strength? I couldnt imagine all that tape being too light either, what do you think the differences in weight are between the two? What about painting? I wouldnt mind painting over top the tape to get rid of the tape lines. If covering is strong enough however, I have no problem going that direction.

My last question is about your guys' choice of radio equipment. Is it worth spending the extra money to get into micro servos or do think standards will suffice? I know its probably smart to get a smaller battery, but what about the reciever? Im a futaba guy myself and if possible, I like to continue with the trend.

Anyways, thanks again for the all the help guys. I will definately keep you updated with pictures when I do come to a conclusion, sounds like JKA for sure. Have a good rest of the day and I look forward to your responses.

RE: Foam Kit Building
 

I've seen the Corsair fly, and it's pretty good. The Zero is smaller, but I don't know much about it.

The key thing about the P-47N is the wing area, and to a lesser extent, the wingspan. The P-47N is the largest of those kits, so it handles the weight best and turns tightest.

I wouldn't bother sheeting with wood. Too fragile, though there are some kits out there with Obichei (sp) sheeted wings. Ive also seen them get blown in half in the air, so I wouldn't go that way.

When I did my P-47's, I also replaced the wing spars with 1/8" fiberglass rods. That allows the wing to take a hell of a hit and stay together. Wing strength is important, and those bends in the corsair wing make it hard to build light and strong.

For scale combat planes, I always paint over the tape. You can scuff it up with steel wool or sand paper, then paint. Using "plastic primer" helps a lot.

For heat-shrink, you need low temp. Monokote is right out. Ultracote (best, imho), towercote and econokote are useable, but keep the iron as cold as you can, and move it often. Otherwise you melt the foam.

The plane below is a tape job. It also just got hammered, note the missing aileron linkage, and all the prop cuts in the belly and all the way through the wing. Also the missing vertical stab. This plane was later repaired and is still flying. (the fuse for sure, the wing, I'm pretty sure I fixed, that damage isn't bad) (ok, it's not flying right now. It was hammered again in Detroit, and is on the bench at the moment with more prop cuts to the fuse). The big pink areas on the LE's are from earlier mid-airs that put dents in the wing and scrubbed off parts of the paint, but didn't disable the plane.

Oh, that's another reason to build multiple of the same airplane rather than multiple different airplanes. More than once I've swapped parts, a wing here, a fuse there, to get a flyable plane up. In this pic, the wing is done for the contest, but that fuse is field-repairable if necessary. (I didn't need to, but those foam cuts are non-critical on that plane, and I always have spare tail parts around)

http://www.wheek.org/airplanes/05nats4.jpg

RE: Foam Kit Building
 

For radio gear, lighter is better.

I'm using 350mah Nimh packs in all my combat planes. A lot of guys are using AAA size 750mah Nimh cells as they last all day (I recharge between rounds. I can get 3 rounds on a charge, but prefer not to try).

For RX, you want micro and tough. Hitec is by far the most common RX in combat. The 04(something), is single conversion but very good, and cheap. (not the feather, it's a park flyer RX). I personally use a mix of Hitec 555 and Electron 6 RXs. I also have some FMA duel conversion RX's and a Polk Seeker 6. The Hitecs have proven to be the most reliable and less prone to battle damage.

For servos, I have gone micro. I use HS-81MG and HS-85MG servos in most of my planes. My P-47N's had one servo on throttle, one on elevator and one on each aileron. You can rig a single aileron servo, but I like the easier setup. Also, not having the servo stick up inside the fuse means the wing can move in a mid-air and not jam the ailerons, which is nice.

The p-47N is big enough to fit standard size gear inside though. You'll just wind up a few oz heavier. Mine were built to the old 3lb weight limit, and they just made it with an OS .25fx on mousse can.

My old P-47's (and a P-36 I picked up from who-knows-where, before I got the P-47's) (note the tape repairs on both P-47s)

http://www.wheek.org/airplanes/mac23.jpg

RE: Foam Kit Building
 

Kirk's info is right on. Except for the packing tape thing, but to each his own. I have had tape lose its adhesion along the edges from fuel seeping under it (which is the main reason why I switched to Econokote). I never had the problems he describes when using Econokote. Most dents are easily removed with a heat gun (which also causes the foam under it to swell some and sort of fill the dents back in). Prop cuts can usually be taped over quickly for field repairs without much (if any) loss of membrane strength. I usually use white Econokote, then scuff it with steel wool & paint over it.

As for other JKA kits:
Corsair - Builds heavier than the P-47 due to the gull wing, and consequently is a step down in terms of performance compared to the P-47N. Wingspan is limited to a maximum of 44" for 2610.
Zero - Easy to build and fun to fly. It is a real rocket with a stout .25. Wingspan is limited to a maximum of 43.5" for 2610.
Ta 152H - Absoluely great flyer. Flys much like a pattern plane. Builds lighter, but has much less wing area than the P-47N. Wingspan can go up to just over 51" and remain legal for 2610. Narrow chord wing is thin and nowhere near as tough as the P-47's.

The best by far:
P-47 (built as an N with a 46.5" wingspan) - Great flyer with the lowest wing loading of all the JKA kits. Super tough, easy to repair and plenty of places in the massive fuse to fit any size radio gear. It does build heavy due to the large fuselage.

Long wing span is important for grabbing streamers, and weighs heavily on my choices. Lots of wing area is also important to reduce wing loading.

D

RE: Foam Kit Building
 

Odd. I've never had a problem with fuel getting under the tape edge. But I am picky about my brand of tape. I always use Uline brand, I find it has better glue than 3M or some other brands. I do mist the foam with 3M-77 before taping as well.

I did have a couple of wings done with covering basically explode when hit, and I've had taped wings have the foam fracture in to a handful of really big chunks, but stay together inside the tape. Either way, you're going to crash, and the wing is done for the day, but I find having the parts makes it easier to fix :D, and sometimes you can aim the crash.

When using Ultracote, I use clear. I'm going to paint it anyway, and of the plastic film coverings, white is the heaviest, black is the lightest tinted, and clear is noticeably lighter and I find it easier to work with. (white heat shrink is heavier due to needing more pigment to make an even color. It's not a big difference, but it's non-0). I really like working with the clear ultrakote.

Tape vs covering really is personal preference though.

RE: Foam Kit Building
 

Good deal, its sounds like you two are both in agreement as far as each of the planes goes. I would have never guessed that the p-47 would be so competitive due to its size. Well that pretty much settles its for me than on which set of aircrafts ("aircraft" singular if the wife asks) to purchase. I'm still in a toss up as far as what method of covering to do. I guess I have a little while to decide but honestly, I think I might go econokote like Demon suggested. I could do both and find out which is the most compatible for me. Montague - you said that Uline brand tape with 3M-77 spray glue works the best? Is there anything else I might need to prep or seal the covering? Demon - do you seal the paint after applied to the econokote? What kind of paint do you guys use?

As far as engines go, what manufacturer or type would you guys recommend? I know those OS .25 FX are awesome engines, the whole FX lineup is great. What about Norvel .25 plain bearing engine that is offered in the combo deal with JK Aerotech? Have you two had any experience or luck with that engine?

Once again thanks for all the help and input you two have given. Its been very helpful and fun learning the new tricks and technique for foam combat, I just don't want to steal all your good ideas.

RE: Foam Kit Building
 

Also by the way Montague, nice pictures of your planes you posted. It looks like you are a pretty serious contender. I'm excited to get my new fleet up and on the assembly line so that I can get you guys some pics as well.

RE: Foam Kit Building
 

If the paint used is not fuel proof, then yes it gets a sealing coat of clear. I've used Krylon Acrylic Clear (both Satin and Gloss), Pactra Formula U flat clear polyurethane, Top Flite LustreKote Flat Clear and Cheveron flat clear. The Pactra Formula U and Cheveron flat clear paints appear to be no longer produced. The Top Flite LustreKote paints can attack plastics (such as canopies), so be careful using it. The Krylon Acrylic Clears are the least expensive, but the satin does not give a 'dead flat' finish.

Depends. It is best to avoid multiple coats of paint to keep weight down. No primer, just apply the paint directly to the covering. For camo colors the cheap way is to use gloss Rustolium colors (not their flats or metalics). This gives a durable fuel proof finish, but is glossy (see the Hellcat). For a serious camo scheme, Testors Model Master paints shot on through an airbrush is best. This finish must be fuel proofed with a clear coat (see the Hurricane). But there are a lot of variations, so use your imagination and good sense. The P-47 pictured was covered with OD colored packing tape, then camoed with Rustolium gray. I use sign vinyl (same as "trim sheet" and available from Harbor Sales linked above) for trim and markings - including the Invasion Stripes on the P-47.

The Norvel engines have proven to be inconsistant in quality and performance. Some folks swear by them, others refuse to use them anymore (I fall into the latter group). IMHO, the best .25 combat engine is the OS.25FX.

HTH,
D

RE: Foam Kit Building
 

My god man, that's what these forums are for! :D Seriously, steal away. There's no sense in not starting with all the info you can get. It does make sense to try new things on your own, and see what you like and what you don't like. Eventually, you'll figure out what you like.

For engines, the Webra .25 is the current hot engine. It's powerful, and generally easy to set up. I have 4 of them, and I like them a lot. But they arne't perfect, they don't always take crashing well, and I did have one break a conrod (it was replaced free by Horizon). But the OS is easier to set up and run, has very good power, and less downsides than the Webra. I've never run a Norvel .25, so I can't comment on them specifically. The OS is the most common engine in combat due to it's power, reliability, durability, and ease of running.

I don't consider myself a paint expert by any means.

I do my painting with household laytex paint these days. That's what the Firebrands are painted with. The p-47's were done with something out of a rattle can, but I forget what I used.

I do topcote the laytex with lustercote flat clear from topflight. I still have occasional problems with fuel proofing if I get in a rush and don't allow things to dry long enough, or I do a bad job with the clear coat. But it's been good enough for combat.

Using the plastic primer really helps the laytex stick to the plastic covering. But primer is heavy, so I use just a little of it, not even a solid coverage. It's not critical, it just helps.

One of the reaons I use laytex paint is that I don't have a good spraying area. I can shoot the laytex through an airbrush in my basement with out needing a full spray booth. The smell and fumes are less than I get when I repaint a room. The clear and primer I have to do outside though.

RE: Foam Kit Building
 

Try Foam and Brown Paper. This is stronger and stiffer than tape. See http://www.rcgroups.com/links/index.php?id=3544

for a good "how to" article.

Nearly everybody in the UK uses this method. Mainly Models do several kits which provide a good starter but lots of the guys cut their own. The TA 152 can be covered in paper but it is a long thin wing and although strong enough, I glass mine now. The Fuz is papered.

Here are some before and after shots. Everything flew again some on the same day! 5 minute epoxy is wonderful!

RE: Foam Kit Building
 

The Jug benefits from swinging a little bit longer piece of wood. The Norvels like 9 inch props but the FX will swing a 10. Little more umph in the launch and acceleration game. Once in the air, I was looping and combating with a failing Norvel giving just over 1/4 throttle no problems looping, shucking and jiving, just no high end speed. That big old wing with a ton of area really comes in handy.

RE: Foam Kit Building
 

This is a perfect example of why NOT to use brown paper and glue over foam:
http://image.rcuniverse.com/forum/up...53/Ki18613.jpg
You can't get cuts if your plane is a pile of parts laying out on the field.;)

The other methods described by Kirk and I allow the plane to fly away from most midairs.

D

RE: Foam Kit Building
 

This is a great example of a JKA kit vs another not-quite-as-well armored plane. First pic is the mid-air. Second pic is the two planes involved afterwards.

http://www.wheek.org/airplanes/zaverton3.jpg

http://www.wheek.org/airplanes/zaverton4.jpg

RE: Foam Kit Building
 

Brown Paper method eh? J.Duncker - thanks for the new idea in covering. Sounds like it works alright for you guys, I think personally Im going to stick with Demon or Montague's advice. Nothing personal but it just seems like more covering work then I would prefer and Im still convinced that it not hold up as well.

As far as engines go, Ive never heard of the Webra .25 before. Im going to have to take some time and research some about it. Im always up for trying new things, how much do they usually run for?

In regaurds to your idea about priming the plane prior to painting, is it possible to just sand and coarse up the covering instead? Like you mentioned, priming just adds another coat and weighs the plane down some more. I guess it probably helps with fuel proofing a bit though.

The more and more I hear about the durability of all the JKA kits, the more confident I am to actually witness outcome of a mid air or two. Kirk - those are some quality picture you got of the midair and aftermath. Im simply amazed at the difference in fate between the two different aircraft. I am definately sold with JKA's durability. I really like your covering job on the P-47, how did you get that silver/chrome finish? Is that just covering or did you whip something else up? Also what color do you guys paint your canopies or how do you finish them?

RE: Foam Kit Building
 

That JKA P-47 wasn't mine. (I did take the mid-air picture though. Mostly luck).

I'm not totally sure how he got the bright metal finish. I *think* he got some silver tape from JKA when he bougbht the kit. I'm pretty sure they sell it or used to sell it. Other than the canopy, I don't think there is any paint on that plane. If you want heatshrink, I think Ultracote might make a silver or something close. With a little thought you might be able to get away with no paint at all. (A lot of guys choose color schemes for scale combat planes that require no paint. Me, I dig camo schemes, so I am forever painting. More work, but I like the look).

Yes, you can just scuff up the tape or covering and paint. It works better with some paints than others. Since I like to paint with Laytex house paint, the primer really helps the paint grab. It doesn't help with fuel proofing at all, just with keeping the paint from pealing up off the plastic. If you can use some more fuel proof paints, when you'll have less trouble and won't need to prime. Demon's done more work with differnet kinds of paints than I have.

A lot of guys paint the canopy white or silver or black. Paint it on the inside, and you can use just about any kind of paint you want.

The Webra's are imported by Horizon, I think. I don't know if you can get them from their website, but one place I've bought them is quantum models. It's about the same price as an OS, but it doesn't come with a muffler. Since I run them with mousse cans, not getting the muffler isn't a big deal to me. Though if I fly that engine in 2548, I might have to go buy a couple Webra mufflers seperately.

A while back, Demon posted a really cool thread on here about how he mods the JKA kits to make them look better. I used a bunch of his ideas when I built mine a while back. The coolest ideas are making a plug and shrinking cowls out of soda bottles instead of using the coro cheeks, and putting in a little something to reinforce the fuse. The JKA kit uses coro on the outside to make the front of the fuse stronger, I think if you cut a curved back edge on it, the foam is less likely to fail right at the edge of the coro.

RE: Foam Kit Building
 

Thanks for the kind words. Glad the info was useful! I ran a search and found that thread burried WAY back there...
http://www.rcuniverse.com/forum/m_44.../tm.htm#448451

HTH,
D

A couple more notes...
If I intend to paint the inside of a plastic canopy, I use Rustolium gloss paint in either Harbour Blue or Smoke Gray- usually the blue. Just scuff the inside and squirt it on.

The pop-bottle cowl article was moved to:
http://www.rccombat.com/asp/workshop...le%20Cowls.htm

That article might be password protected. If it is, drop me a line and I'll email it.

RE: Foam Kit Building
 

Geeze, I've been delinquent in reaffirming what Clean posted - the .25FX does indeed swing a Master Airscrew 10x4 with authority. That prop is on all of my .25FXs in my combat planes. Tons and tons of pull for easy launches and constant turning, yet enough speed to be competitive.

D

RE: Foam Kit Building
 

Oddly enough, I was running the MAS 9x4 on my P-47's, OS .25FX and mousse can. The plane was a tad slow compared to some of the top of the line planes at the time, but since I managed to keep it at 3lbs, it turned with, or inside, anything. I never did try a 10x4.

Haveing a good cowl on there makes a huge differnece in airspeed, btw.

And don't skimp on the sandpaper steps. The more round the fuse, the lighter and faster the plane. I'd seen a couple that were still very very squared off. They flew, but never quite as well as I think they could have.

Btw, like any combat plane, CG is key as well. Get it back as far as you an manage, and you pick up airspeed and improve turning radius and rate of change of turning radius.

RE: Foam Kit Building
 

Im surprised that you guys will turn a 10x4 on a .25fx. Im sure it definitely works, I think Im going to try the same thing, speed is great but I prefer the strong hand launch as well. How do you guys reinforce the bottom of your planes for landings? Ive seen a couple different methods but what do you guys prefer?

I broke my promise to the little lady of buying another plane (haha) and ordered a JKA Zero up today. I figured it was a simple first plane to start with since building and flying is straight forward, it looked like a good first foamie. It will most likely be a trial plane to experiment with like you guys suggested. I'll probably then start up a fleet of p-47 shortly here afterwards so I can be half way competitive. As soon as I get the kit and start with the construction, I'll update you guys with some pictures. Thanks for all the great advice this far, it sure has helped.