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Old Jan 22, 2012, 10:07 PM
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Build Log
MIG 31 FIREFOX scratchbuild

hi guys just thought i would start a build log of my plane..im sure i will have tons of questions along the way as this is my first attempt at a scratchbuild..and come to think about it the only other plane i build was a cadet senior about 10 years ago and concider myself a total noob to the hobby.i probly should have started with an easier plane lol..i looked for about a week before i decided ..sooo many great planes out there..and came across the firefox pics..i remember going to go see this at the theater when it came out.i thought the plane had alot of character and was way cool so..

ive been working on it on and off for the past week.made from fan fold foam (blue foam)3mm?and going to cover it with 1/32 sheet balsa(exo-skeleton)..not sure if i will be making a plane or a lead brick..lets hope not

it is 48 in. long and not sure how wide yet as in still building the main body and have not figured out how far the wingtips will extend.im supprised i havent messed it up allready (mabe i have but dont know it : ) )
it still looks like it will fly so i will continue to work on it..ill try to figure out how to upload pics of my current progress...thanks for reading my wall of text
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Old Jan 22, 2012, 10:15 PM
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hope this works..
im not going off any plans really just kind of winging it....lol pun intended..i have no idea how scale this will be when im done.just trying to get this thing to look decent..no clue on the power system as i have no clue how heavy this thing will be till i get further in the build..the openings are 3 1/2 in. tall and 4 in. wide i got 2 64mm edf's and 2 40 amp esc's out of a dynam a-10 when sliped in there look really scale.im sure 70mm fans would fit also..90mm might be pushing it size wise im clueless on size of fans and stuff
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Last edited by wind1234; Jan 22, 2012 at 10:30 PM. Reason: information
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Old Jan 22, 2012, 10:47 PM
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this is where i started actually taking pics of the build..heck i never expected to mak it this far anyways lol...i started off with basicly a top and side siloett for my basic shape..doubled up the wings 2x3mm and added 3 more layers tward the front to taper the air foil...what kind of air foil you ask?i couldn't tell you it looks like a wing lol not really a bunch of firefox pics out there like other planes and the ones ive seen are all kinda diffrent.i guess mine will have to be diffrent too..been skining the top with my 1/32 balsa sheet going to leave the bottom unskined till i figure out where all my stuff is going to go
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Old Jan 22, 2012, 11:18 PM
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still got some foam work to do on the bottom (batterydoor,servos,radio,and edf's)just a little note to people thats not worked with fan fold foam.one side has a lil skin of plastic..make sure to peel that skin off if you plan on sanding or shaping the foam..trying to get the sheet balsa to go around some of the contours is tricky to say the least im sure there tricks like wetting it or something but no the less its progressing along..im skining out the nose currently..baby steps baby steps lol
any input good or bad would be most appreciated this being my first scratchbuild i sure need it : )

i just put it on my scale and the plane is at 18 oz....is this thing heavy?
i still got more to add but id say im just guessting here that the plane has 85%? of the weight at this point (not counting radio ,servos,battery motors,ect)
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Old Jan 22, 2012, 11:33 PM
Do it Right, the first time!
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United States, MN, Hermantown
Joined Dec 2008
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Here's few links to check out, enjoy. Check out the RCpowers first.

http://www.rcpowers.com/firefox/firefoxinstructions.htm

http://thinkinrussian.org/, http://thinkinrussian.org/resources.cfm, http://www.globalsecurity.org/milita...refox-pics.htm http://hsfeatures.com/mig31ph_1.htm http://www.aerospaceweb.org/question/planes/q0244.shtml
FIRST R/C MiG-31 Firefox!!! (1 min 42 sec)
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Old Jan 23, 2012, 12:41 AM
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thanks for the links! i ran across a couple of those....i like the powers one but im not a fan of the profile plane look..my bigest concern at this point is weight..im thinkin im going to need a small runway.....im hoping not to have to invest in another powertrain (2 edf's 2 esc's and battery)ill have to run my edf's i got 2 (64mm) and see what there putting out as far as thrust...just guessing here im going to say fully loaded with powertrain and servos and stuff im going to be at least a 2lb. plane...that sounds kinda heavy to me....but ive never done this before so im not sure..the plane has a lot of wing/surface area and im not going for speed.id be happy if it flys at all lol
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Old Jan 23, 2012, 12:50 AM
Do it Right, the first time!
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I wish you the best. It's looking real good so far. And I might say, without some kind of plans, you have got it. By the time I found most of those links, you had already posted several more. Keep up the good work, I'l be looking in on your progress. Mark
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Old Jan 23, 2012, 01:23 AM
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thanks mark..im just makin it as i go i havent even started thinking about control sufaces yet..kinda started out as seeing if i could make somthing semi scale and then i thought about making the main fuse and making a mold so i could do some kind of carbon fiber body(still might have to be an option if it become to heavy) : )
was going to try and make the body real stong or at least as strong as i can and make the wing tips and rear stablizers out of 3mm foam (probly use depron for those....i wanna make it so that there almost kinda tear away where they slide in from the front and cant fly off but if they get damaged im just cutting some triangle peices to slide back in if that makes any sense...with those outer wing tips pointing downward there for sure to get molested prety easy..it will be alot easier to replace a wing tip then try to fix a wing that blended to the body....now when it lawn jarts into the ground...well thats a diffrent story : )
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Old Jan 23, 2012, 03:06 AM
Do it Right, the first time!
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I know what you mean. Been working on my plug over the weekend. Wanted to get more done on it, but there are so many measurements to take, and check, recheck, before you start to cut anything. When you start to cut out gear doors, hatch covers, canopy areas, you only get one chance to get it right. Sent you a PM, it will explain more. did not want to waste you space here. Mark
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Old Jan 23, 2012, 03:51 PM
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got around to doing a really quick test today to see what kinda thrust i can expect..my scale is telling me about 6 to 7 oz. at about half stick and a lil over 10 oz. when i get on it..was using a 2200 mah 20c lipo 40 amp esc and my best guess from what i can deduct from online a 4400 kv motor...not sure tho..
does this sound about right?will i be able to get more thrust if i make a smaller nosel,or is a wide open thrust tube work better?is there anything i can do to get a more accurate measurment?am i not doing something right?is there a better way or something that im not doing or something that will help?any more info i could give you all to help me out?
thanks in advance
steve
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Old Jan 24, 2012, 01:25 AM
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not a whole lot of progress today..skined out the top of the nose tac welded up the rear fins and wing tips to get my final wing span (36 in.)guess im going to have to start thinking about control surfaces....weighed the plane again im at 20 oz. thats with nothing installed..at this point im thinking my powertrain aint going to be enough..im not really looking for speed but just by feeling the plane its going to need to be kinda quick to keep the nose up..this is just me guessing as this is my first jet again any input good or bad would help me out soo much..just an afterthought finding a center of gravity should be real fun : )
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Old Jan 24, 2012, 01:42 AM
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This plane is special! design in simple and i think more suitable to fly than those scaled ones. It is more "RC-ed"

I am facing same challenge as you, I am scratchbuild a Viper-alike RC plane with some mod to suit RC characteristic instead of 100% scaled from the original. Hope we can finish it successfully!
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Old Jan 25, 2012, 05:52 AM
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Quote:
Originally Posted by wind1234 View Post
not a whole lot of progress today..skined out the top of the nose tac welded up the rear fins and wing tips to get my final wing span (36 in.)guess im going to have to start thinking about control surfaces....weighed the plane again im at 20 oz. thats with nothing installed..at this point im thinking my powertrain aint going to be enough..im not really looking for speed but just by feeling the plane its going to need to be kinda quick to keep the nose up..this is just me guessing as this is my first jet again any input good or bad would help me out soo much..just an afterthought finding a center of gravity should be real fun : )
Excellent build!

I like this plane a lot. Suscribed.
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Old Jan 26, 2012, 04:57 AM
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took me a nap after work and woke back up at 1 am with the help of mountain dew i managed to mark and cut out and remove some unneeded foam and weight from the nose of this thing....i freed up 35 grams lol i guess every lil bit helps : )

i was wondering mabe someone is in the know...that would be a lighter covering primer and paint or monocoat?

not sure if i wanna do the classic firefox black or if i really wanna get crazy and do like a futuristic police jet clasic black and white with working red and blue cherries mounted in the wings.....in my brain it looks really cool lol

tell me what you all think... and thanks in advance for looking and comenting : )
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Old Jan 26, 2012, 05:44 AM
Do it Right, the first time!
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check-out the stuff there using on the t-38 thread. Might be just what you are looking for. http://www.rcgroups.com/forums/showt...559834&page=25
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