MIG 31 FIREFOX scratchbuild - Page 2 - RC Groups
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Jan 26, 2012, 10:40 PM
Registered User
just a small update...got a lil more skined out today cut out some of the wing for my elevator..mocked up some peices of wood that im going to attach the wingtips too its taking a good bit of time to get this skined as i got very few pins to pin the sheet to the plane so still working small areas waiting for that to set up /repeat lol weighed it again today shes setting at 19 oz. ive manage to shave an oz. off dont think i can get it any lighter at this point ...its only going to go up at this point..i was going to go with strait foam for the wing tip and vetical stabs but i dont think thats going to get it be to floppy so ill probly go ahead and skin them as well 1/32 balsa aint going to add but a few grams anyways no bigger than they are..soo yea not much but its something hope you all enjoy : )
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Jan 26, 2012, 10:44 PM
Registered User
LuvEvolution7's Avatar
WOW, this is so cool. 100% subbed.

Jan 27, 2012, 12:18 AM
Capt. Z
falcon5's Avatar
Wow looks GREAT!!!..nice work.
Jan 27, 2012, 11:53 AM
Jet's are cool!


After my first foam build think I found my second! Is there any way you could vome up with some basic plans or at least measurements? I guess well just have to wait to see how it performs.
Good luck with a trmendous idea!
Jan 28, 2012, 12:58 AM
Registered User
all i did was google mig 31 firefox pics and it come up with a few that had a side view and top view and i got my computer run through my bigscreen tv (52 in) and found one and opened it up on micosoft paint and took some sizes down end up being 4 ft. long and 3 feet wide....it prety much started off like a profile plane i drew up a side view of the fuse and the top view i used 2 peices of 3MM foam stacked..then i made the exaust tubes. thos have been by far the hardest part at just about every pic you can find of a firefox there kinda diffrent some are more round or a little taller or what have you its all in what looks good to you or fuctional make sure you make them at the same time cause its definatly inportant that they look the same..then i cut some slits in the wing and slid them in at this point i could only move them up and down but not side to side and just kinda moved it to where it looked good..if any that make sence then i just filled in the rest the profile of the fuse so it looked full... when i did this i didnt have it flat or something and the nose had a twist in it so i had to cut the front fuse off and redo it straight....the joys of learning as you go...and just keep adding things that look good i didnt think i was going to get that far or i woulda took some pics lol.......im at the point now where i need to figure out what i need to do about a power system i have started sheeting the bottom yet in case i need to cut into the foam to add servos or edf mounts and cant do that till power system is inhand...not sure what kinda servos to use either any suggetions would be great lighter the better i guessing or at least im shooting for a plane around 2lb auw dont know how realistc that will be but we will see : ) and still need to figure out the vertical stabs and wingtips not sure if i wanna do those in depron or sheet up some my blue foam that i used for the body i just know these will be the first things to get molested wanna make them easy to change out...probly make some brakes 70 degrese for the stabs and 20 for the wingtips have them slide in through the front and so they wont come off during the flight...still got to do the little forward wings...should order a minicam so i could at least film the epic crash being as im spending so much time building this thing lol if i had to do it again i dont think i could get it no lighter unless mabe i was to use epo foam... when building dont use no more hot glue or adhesive than you need hot glue will add weight quick....i wish i woulda did some hand launch tests while it was still in its profile form just to get a basic cg....didnt get nothing done today as i just got home from work and its 1 am here but got all weekend off so hopefully have some more progress pics...ive rambled enough thanks for all the positive feedback guys
Jan 28, 2012, 12:47 PM
Carbon fiber is our friend
Steve C's Avatar
Awesome project! I was10 when this movie came out and I thought that plane was really cool. I saw the movie again last year and I think it holds up pretty well. What a job they did making a full size model out of real stuff instead of in a computer.

The one in the video hardly flies like the supersonic movie plane does it! Flat foam does have it's place, but it also flies like flat foam.

There are a few fantasy fighters that I think would be popular EDF's I'll be watching
Jan 28, 2012, 09:05 PM
Jet's are cool!
I guess that doing what you did is a little above my head. I commend you on your ability to create something from scratch like that, it is awesome..
Jan 28, 2012, 09:11 PM
Jet's are cool!
Originally Posted by wind1234
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
It looks to me that this thing is begging for a twin 80mm setup. I know it will be expensive, but this airplane has plenty of wing and if balanced correctly will fly great.
Jan 28, 2012, 09:56 PM
Registered User
ok so i been kicking around the idea of having my landing gear made out of carbon rods... 2 rods in the back and 1 in the font these will be bent like a bow kinda like the lead springs on a truck does that make sence?....what these are going to allow me to do is takeoffs and landings from grass or concrete i expect good shock absorbing and travel for hard landings i wont have to worry about having to retract or having heavy wheels or drag while in flight...and while flying i doubt you will even see them much....most of the air intake at least 75 % is comming in through the bottom so a belly landing in any kinda grass would result in a salad shredder....dont know yet like i said just kicking around the idea...what do you all think of this idea?good/bad has anyone tryed this?.....on a side note rifel rests make great plane stands : P
Jan 28, 2012, 10:13 PM
Registered User
so today i addressed one of the places on the bottom thats been buggin me,,the transition at the entrace of my air intakes...the best part about making a fictional plane is you can allways say thats how its supposed to look lol...so after goofing around with it for a littlebit......i ended up with what you see here
Jan 28, 2012, 10:38 PM
Registered User
just some pics of the bottom currently...not to shabby for just eyeballing i wouldnt wanna put a lazer on it lol...guess im going to have to pick out some fans the exaust openings are 3 in. or 76 mm i could cram in 3 1/4 in. or 82 mm fans would half to slightly modify the ducts if i wanted to go with 90 mm so im going to have to buy 2 fans/with motors 2 esc's and a brick of a battery....should be getting my tax refund in a week or 2...i really hate to use my credit card...oh well any suggestions on some good light servos thats not going to break the bank....
Jan 30, 2012, 12:33 AM
Registered User
goofed around all day did managed to get me some canards mocked up..took some small brass tubeing and cut some 1/2 in. peices and just set them in the fuse ran a carbon rod throgh them and taped on the canard just to see how she looked.....spent most the day window shoping online : ) did manage to find a 77mm (3 in.) edf 7 blade unit they was about 17 dollars no motor i went ahead and poked the button..this is the biggest fan i can put in the plane without modifying should be a slip in fit...i wanted the 90mm fans bad they was only a couple bucks more but i cant carve any foam away to make them fit i would have had to alter the looks of the plane...i know with the help of you all and some on my part that we can get the power we need to get this baby off the ground!!

ok the fan
3.175 shaft
31mm limit diameter
recomended motor 28 35 8 turn ( 11.1 ~ 18.5v )
here is where im lost ..need some motor, esc, and battery suggetions..
i wanna get the most power i can out of these..
thanks in advance for the help guys : )
Jan 30, 2012, 12:48 AM
Registered User
omg.. sry guys i forgot to flip my pictures around lol the upside down one is one showing how far forward i can mount the fan inside ....the fan showing is a 64mm that will be way underpowerd with my 3s 20c 40amp esc the motor is el cheepo also was only getting 10 oz.of thrust at full stick....going to look and see what i can find out about a 5s battery/motor/esc combo again thanks for the help
Jan 30, 2012, 02:02 AM
Plane crazy
Tartago's Avatar
I had good results with this servos:

Jan 30, 2012, 02:06 AM
Plane crazy
Tartago's Avatar
For EDF and motor get 200w per pound of plane weight.

Check the Mercury 64mm 4700kv or 3700kv.

ESC should be around 60A.

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