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Jul 19, 2008, 12:56 AM
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tzyoung's Avatar
Build Log

1/12 House of Balsa P-51 with a twist of foam


Since the proliferation of powerful, inexpensive electric power systems, there has been a big trend in converting the old glow designs to electric power. However, I tend to do things a little different. I am taking a balsa design, building it from foam and then powering it with electrons.

I would like to share my progress on a P-51 mustang I am building from H.O.B. plans by Fred Reese.

The plans were used for the critical dimensions and general layout, but use of Protection Board meant that the parts like formers needed to be adjusted slightly.

I hope to achieve an aircraft that is indistinguishable from the balsa kit but built from much cheaper foam.

You will notice that there are no pictures of fuselage construction because I got lazy and failed to take pictures, but the pics attached should give an idea of how the plane is built.

Enjoy
-Trent
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Jul 19, 2008, 01:06 AM
My plans are in my blog
Rusty-Gunn's Avatar
This looks like a nice plane, you're doing quite well. heres wishing you the best with the maiden.
Jul 20, 2008, 09:27 AM
My plans are in my blog
Rusty-Gunn's Avatar
Looking good.
Jul 20, 2008, 10:45 PM
GO FAST OR GO HOME!!!!!!!
hey i have a house of balsa p-51 gas and flys great but i wanna make it elec any ideas?
Jul 21, 2008, 08:44 PM
Registered User
tzyoung's Avatar
Well the one I have hanging in the basement has never flown. It actually belongs to my dad, but I think I almost have him talked into letting me maiden it. Anyway, I think that 200 watts would be all it would take to give it great performance at 100 watts per pound. I don't have any suggestions for a power system off the top of my head, but my motor turns a master airscrew 7 X 4 at about 14,000 rpm 17 oz thrust and pulls around 22 amps on 3S.

Also, I will add that the box gives a flying weight of 22-28 oz for the balsa plane. My foam version looks like it will come in at about 18 oz at the heaviest. So the performance should be great... I hope.

-Trent
Jul 21, 2008, 09:22 PM
GO FAST OR GO HOME!!!!!!!
hey thanks for the info and they fly great you will love it
Jul 22, 2008, 12:17 AM
BPD
BPD
DHMO kills!
Looks great. I will be watching with interest. I have an old plan for a balsa T-33A that is suppose to be for monoline or free flight, I want 4 channel control. With the new EDFs around I should have no problem replacing the Cox.049 and fan blade. I never considered building with foam, not sure why it just never occurred to me to try it.

BPD
Jul 22, 2008, 01:38 AM
"Experienced-Crasher"
Demon-Leather's Avatar

Should Fly Great!...


And should be about half the weight of the traditional balsa build! I've got the plans for almost all the H.O.B. 1/12 scale kits, and they ALL are the basic same layout. My little 20" span copy of Ken Willard's "Roarin'20" flies better than the origonal I think (also out of fan fold).. so your 36" span should be phenominal! Don't glass it, or add heavy paint... cover it in Solite silver and do the trim like the H.O.B. Box in invasion stripes. No one will ever know it's foam! Bob
Last edited by Demon-Leather; Jul 22, 2008 at 01:47 AM.
Jul 22, 2008, 12:34 PM
Registered User
tzyoung's Avatar
Hey Demon-Leather,
It is nice to finally get the attention of one of my heroes on this forum. I have seen a lot of your builds and I too started as a balsa basher, but turned into a fanfold convert. I know all about the solite over foam thing from when I did my fanfold Pitts special (https://www.rcgroups.com/forums/showthread.php?t=821105) and it also shocked everyone when they saw that it was blue foam.
My reasoning for using glass on this bird is twofold. I'm going to build it sans landing gear so I need all the extra strength I can get for those belly flop landings. I also want to do Reno racer type scheme and test out the Candy Paint system that I have been working on for these electric models. I'm planning a silver and Black cherry scheme that should look great.

BPD,
like I said before, I cut my teeth on balsa free flight models and stepped up to balsa R/C. Balsa is nice but foam build phenomenal looking planes much faster and lighter (sometimes). Be sure to put up pictures and do a build thread when you build that T-33 I would really like to see it.

-Trent
Jul 23, 2008, 12:15 AM
"Experienced-Crasher"
Demon-Leather's Avatar

Well...


Geeze,... Now I'm gonna blush! Well If ya' gotta glass... ya' gotta glass. But I can give you an easy fix for the gear. Just install balsa blocks (or as short as the gear width is on a P-51) one long soft balsa block in the wing between the gear. scab the top of the block (when I say block, Im talking rougly 1/4" x like 1.5")with a small 3/4X 3/4" piece of 1/32 ply where the gear strut should be. Then take a piece of 3/32" fiberglass kite rod, wrap an "L" wire axle to it say 3/4 X 1" (one in. part being the axle) And wrap it with thread to the 3/32" kite rod & soak in CA . Drill a 3/32" hole in the block, install the kite rod, true the wheel angle (don't forget a bit of toe-in) and drip CA down the axle into the hole in the block. You now have "springy" gear that will take a severe whack, and absorb 90% of the shock!.. and, it's waaAAAaaay frikkin light! For wheels, It's going to be hard finding 1/12 scale wheels that are light,.. just cut some balsa disks the right size/scale, & CA together. If you use a compass, you have a centered drill hole. You can bolt it up to a extra thin screw with nuts & washers, & "turn" it in a hand drill. Using an Exacto & a sanding bar as cutters. You can even turn the center out a but & add those WWII mag spokes made of balsa sticks. Then, go to Lowes or WalMart & buy a can of tool grip spray or dip.(spray is cheaper most times) Spray a nice rubber tire coating on your balsa wheel (you can even cut tread with the Exacto) install aluminum or brass btubing in the hole for a bushing, and paint the "metal" part of the wheel magnesium. I'm STILL agaist glassing..(all that weight means speed, & that's NO fun for Me ) I'd use your waay kool paint job on the inside of some lite Dolcuam (spelling ) covering and apply it. It's like clear monokote, (but LOTS lighter) and the covering acts like a rich, deep "clear coat"...Glassing, will also remove the "bounce-ability" of the model in crashes...a sure death-warrent for me! Bob
Last edited by Demon-Leather; Jul 23, 2008 at 12:22 AM.
Jul 23, 2008, 05:17 PM
Registered User
tzyoung's Avatar
That is a cool solution to the problem of landing gear on these foam planes. I bonded solid pine blocks to the balsa spar in the wing to attach removable landing gear much like the plans. The reason for me leaving off the gear is that I mainly fly at a large field at Doretha Dix hospital in Raleigh, and the grass there is never short enough for most parkflyers to land without nosing over. It actually does less damage to just slide em in.

Give my way cool paint job a chance . The motor I am using is one I wound for a 23 oz F-18 pusher. I think speed and power should be a moot point for this aircraft. But that doculam trick is actually a pretty neat idea and I may use it on a future build.
Jul 24, 2008, 02:22 PM
Registered User
tzyoung's Avatar
here is a progress update. The wing is now glassed and I am waiting for coat #2 of primer to dry.
A word about primers. One of my pictures shows the type of primers I am playing with on this bird. My old standby is the Krylon H2O primer. It works ok but splutters when sprayed and just doesn't act like normal spray paint. So I am trying out the Killz2 latex primer. I can apply the killz with a brush or with my airbrush so it works out cheaper than the Krylon.
This wing is getting a good wet sand with 600 grit paper between each build of primer. That will take care of the dimples that remained after the application of fiberglass. I am going to all this trouble because my topcoat of paint will be a transparent color and I need to eliminate any dimples where the paint might puddle.
Thats all for now... I need to get back to work.

-Trent
Jul 24, 2008, 10:56 PM
Registered User
tzyoung's Avatar
I got the fuselage ready for some fiberglass. Here are a few pictures
Jul 26, 2008, 05:23 PM
Erik with a K
tvcasualty's Avatar
Nice build log! Good pics!


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