Foamies Talk about building, power setups and anything having to do with e-powered foamy planes!

F-82 Twin Mustang!!!! With Pics

Old 09-22-2009, 02:52 PM
  #1  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default F-82 Twin Mustang!!!! With Pics

Hey everyone,

I have recently purchased a super cub as a start to my RC airplane hobby. So I'm only about 2 months into the hobby but i have learned to take off, do some aerobatics, and land. I still need to perfect my flying skills but i have decided to give my building skills a try.

I have learned an immense amount of information about building and flying RC planes from reading this site and others. About 2 weeks ago I decided to start building my own plane. After seeing a P-51 mustang fly I decided I really wanted one for my next plane but while researching it I stumbled upon the F-82. It looked like one of the coolest looking WWII planes I've ever seen!!! I was very excited and decided that the F-82 was the way to go. (It’s like two mustangs in one )

So after searching online for a good set of views of the plane I decided on these below....

I inserted the views into AutoCAD and scaled them so that 1' on the plane equals 1" on paper. Then I went ahead and edited the numbers slightly so that majority of the dimensions came out to numbers no smaller than 1/8 of an inch.

My total wingspan came out to be 49" so I believe this to be a 1/12 scale of the plane.

Once I had all (or most) of the measurements I went to Lowes and Home depot to see what they had for flat sheets of foam. At Lowes I found a one inch thick 4' x 8' sheet of insulating foam that seemed light enough but yet dense enough so that I could cut it with a hobby knife, and also sand it.

I brought the piece home and immediately began to mark up the foam according to the sizes I would need. I began with the wing and then with the fuse sides.

Cutting the foam was very easy, and by using a long ruler and a T style metal ruler that is used for cutting drywall, I was able to get very straight and accurate lines. Once I started to cut the pieces out for the fuse I ran into a small problem. The foam I bought was 1” thick and if I was to use it to make the fuse walls the space inside the fuse would be too small to fit all the electric components. I decided to split the foam in half in order to have ½” size pieces. This worked pretty well except for the fact that when cutting a piece that’s 6” x 13”x 1” to get half the thickness it becomes really hard to keep the knife going into the foam perfectly straight and so the pieces don’t always come out perfect.


The other problem I ran into using the 1” thick foam is that the scale wing on the plane should be about 1 ½” at the thickest point (where the wing meets the fuse). Since I was limited by the thickness of the foam I decided to slightly redesign the wing to allow it to be only 1” thick. This is the biggest thing I’m worried about so far and is probably the only part of the plane that isn’t exactly to scale.

When deciding on how to create the airfoil I also ran into a small problem. HOW TO DO IT! J I decided to stick to the scale airfoil (minus the true scale thickness) and did some research. I found a lot about people making foam cutters that basically cut the foam by melting it at a certain point. They basically heat up a copper wire by running a current through it and run it through the foam. I tried this but was very unsuccessful. I didn’t want to buy a power source and tried using some things I could find around the house but with two failed attempts and two burned out AC to DC power supplies (12v and 18v) I decided to try just cutting it one small piece at a time. Needless to say this took a very long time. After cutting away as much as I could with a box cutter type knife I decided to sand the rest of the wing smooth. With about an inch of dust on the floor I was done with the wing it looks pretty good.

By the way, about the wing, from what I can tell about the design of wings on most rc airplanes the CG (center of gravity) is at the thickest part of the wing…am I right? According to this rule, my CG is about 1/3 of the length of the wing from the leading edge….let me know if you think that is wrong.

I used a Few different types of glue on this plane and learned a few things by trial and error. First of I used 5 min gel epoxy which worked very well on holding the large and small pieces of foam together. I used this epoxy to attach my hinges, and foam that had to be bent into place and held there with clamp or by hand until it hardened. This worked ok for hinges except for having to cut away all of the extra epoxy in order to provide the hinge with full range of movement. One thing that I learned about using the epoxy is that once it’s fully hardened, usually overnight, it’s almost imposable to cut. It becomes so strong that when you try to cut it, or sand it, it breaks off in pieces taking a large chunk of foam with it.

After learning this about epoxy and foam, I decided to try a different kind of glue. The yellow glue that you see is wood glue. It takes much longer to dry (needs to be clamped for 6hrs and reaches full strength in 2 days) but can be wiped away with a wet paper towel during the first few hours and after about 6 to 8 hours it cuts very well with the foam and can be trimmed as needed. When it is fully dried it also sands much better than the epoxy.

After about a week and a half of working on it…….after school and after work…. I finally have most of the main body structures done and combined. The two fuses are held together parallel to each other by the tail elevator/wing ( I’m not sure what that’s called) and by two metal rods. They’re both glued with epoxy into the fuse and this allows me to just place the two fuses onto the wing as if they were one. Aligning them is also easy this way since they both move together and always stay parallel.

I still need to come up with a few design solutions such as how to attach the two fuses to the wing so that they can be taken on and off for transportation. I was thinking about wing bolts but I’m hoping that there is a better solution. Also I need to figure out where to put the hatch for the electric systems on the fuses, so that I would have quick access to all the electric components and will be able to put the batteries in and out without much difficulty.

Hope everyone enjoys reading about my experience of scratch building a scale foamie

Any and All input/ideas/thoughts/comments would be very helpful

Thanks,
D22av
Attached Thumbnails Click image for larger version

Name:	views 1.jpg
Views:	477
Size:	113.5 KB
ID:	109714   Click image for larger version

Name:	views 2.jpg
Views:	465
Size:	120.6 KB
ID:	109715   Click image for larger version

Name:	P1030062.jpg
Views:	498
Size:	524.2 KB
ID:	109716   Click image for larger version

Name:	P1030071.jpg
Views:	434
Size:	544.1 KB
ID:	109717   Click image for larger version

Name:	P1030057.jpg
Views:	453
Size:	622.0 KB
ID:	109718  

Click image for larger version

Name:	P1030058.jpg
Views:	379
Size:	547.0 KB
ID:	109719   Click image for larger version

Name:	P1030060.jpg
Views:	418
Size:	481.4 KB
ID:	109720   Click image for larger version

Name:	P1030061.jpg
Views:	406
Size:	493.2 KB
ID:	109721  
d22av is offline  
Old 09-22-2009, 03:30 PM
  #2  
Don Sims
Administrator
 
Don Sims's Avatar
 
Join Date: Sep 2005
Location: Middle Tennessee
Posts: 13,705
Default

Great looking project!
Don Sims is offline  
Old 09-22-2009, 05:25 PM
  #3  
dmmalish
r/c crash test "DUMMY"
 
Join Date: Jul 2006
Location: eaton rapids michigan
Posts: 922
Thumbs up

that looks to cool i need to try building something out of foam someday. nice job so far
dmmalish is offline  
Old 09-22-2009, 06:27 PM
  #4  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default Some more additional Info- and more pics

Since I already ordered all my main electric parts I decided to post a list of them for everyone…

Motor – 2 x 3530-14 Outrunner Brushless Electric Motor ( http://www.headsuprc.com/servlet/the...980/Categories )

ESC – 2 x 32 Amp Power Up Brushless Motor Speed control (http://www.headsuprc.com/servlet/the...ushless/Detail )

UBEC – 1 x (since I’m going to have 6 micro servos and 1 retracts servo that I might want to put in later)
3 AMP Switching (http://www.headsuprc.com/servlet/the...-3-Amp-/Detail )

SERVOS – 6 x HXT900 9g / 1.6kg / .12sec Micro Servo ( http://www.hobbycity.com/hobbycity/s...?idProduct=662 )

LIPOS – 2 x ZIPPY Flightmax 2200mAh 3S1P 20C (http://www.hobbycity.com/hobbycity/s...idProduct=6306 )

Other than that there’s a bunch of small hardware and accessories I had to buy like push rods, control arms and such…

From what i can estimate/weigh the total weight of the plane is going to come out to be slightly under 3 pounds. I think this motor/ESC/batt should be sufficient

if anyone has ever done something similar I'd love to see it and hear about what worked for you....

comments and any advice welcome,
Thanks
Attached Thumbnails Click image for larger version

Name:	P1030074.jpg
Views:	234
Size:	57.5 KB
ID:	109740   Click image for larger version

Name:	P1030075.jpg
Views:	225
Size:	563.8 KB
ID:	109741   Click image for larger version

Name:	P1030076.jpg
Views:	213
Size:	491.6 KB
ID:	109742   Click image for larger version

Name:	P1030078.jpg
Views:	239
Size:	47.0 KB
ID:	109743   Click image for larger version

Name:	P1030082.jpg
Views:	254
Size:	75.4 KB
ID:	109744  

Click image for larger version

Name:	P1030085.jpg
Views:	217
Size:	61.6 KB
ID:	109745   Click image for larger version

Name:	P1030092.jpg
Views:	233
Size:	615.7 KB
ID:	109746   Click image for larger version

Name:	P1030095.jpg
Views:	267
Size:	537.3 KB
ID:	109747   Click image for larger version

Name:	P1030103.jpg
Views:	237
Size:	611.8 KB
ID:	109748   Click image for larger version

Name:	P1030110.jpg
Views:	223
Size:	52.7 KB
ID:	109750  

Click image for larger version

Name:	P1030109.jpg
Views:	232
Size:	517.5 KB
ID:	109751   Click image for larger version

Name:	P1030115.jpg
Views:	212
Size:	474.4 KB
ID:	109752   Click image for larger version

Name:	P1030124.jpg
Views:	208
Size:	527.2 KB
ID:	109753   Click image for larger version

Name:	P1030129.jpg
Views:	206
Size:	474.5 KB
ID:	109754   Click image for larger version

Name:	P1030133.jpg
Views:	310
Size:	585.6 KB
ID:	109755  

Click image for larger version

Name:	P1030136.jpg
Views:	311
Size:	570.1 KB
ID:	109756  
d22av is offline  
Old 09-24-2009, 07:10 PM
  #5  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

Originally Posted by d22av
I am currently working on my first scratch build foamie and have just received my motors for it from heads up rc.

http://www.wattflyer.com/forums/showthread.php?t=50259

Now I started thinking about possible ways to mount to my fuse. I have gotten a few very good ideas from all the posts and pictures here. Thanks a lot CHELLIE and everyone else.

If you don't mind taking the time, what type would you recommend?

Thanks a lot,

D22av
Hi D22av nice scratch build twin mustang use a wood motor mount like this, and secure it to the sides of the fuse, because those are powerful motors you are using, make the wood side braces about 3" long going into the fuse sides. also make some extra holes in it so air will pass through it, to cool the eletronics. have a hole, port at the rear of the plane or behind the wing as a hot air exit port. if there is a film on the foam, take it off, Take It All Off where you epoxy the wood at to the fuselage, also use some SQ CF tube to brace the main wing, or it will bend and snan Off, in the middle will be fine from wing tip to wing tip, cut a tight slot, and epoxy it in, sand the cf so its rough for better sticking to the epoxy, 180 grit sand paper will work fine, dont breath the CF Dust, its bad stuff, wet and dry sand paper will be better, and use a water hose while sanding, set your CG at 25% back from the leading edge, to start with, thats a very safe place to start at, use a reverse prop on one of the motors, so you counter the torque, have the motors spin opposite one another, looking at the front of the plane to the rear have the left motor spin clockwise, and the right motor spin counter clockwise, juse reverse any 2 of the 3 wires at the motor to change rotation, Hope that helps, Chellie

http://www.gravesrc.com/MILLENIUM_RC...mrcss-fuse.htm

Cdr Did a nice job on his Wood reinforced foamy fuselage motor mounts, here is a good idea of how to do it.






CHELLIE is offline  
Old 09-24-2009, 07:21 PM
  #6  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

On the rudder, you just need one servo , and tie the 2 rudders together, at the back part of the rudder with a linkage, like they do with a biplane ailerons, that will save some weight and a extra servo, use some plastic push rod for the rudder and elevator , it will be much lighter than the metal you are using, and epoxy the outside plastic tube to the fuselage or braces every 3 or 4 inches, Keep up the great work, Chellie


http://www.hobbypeople.net/gallery/578212.asp


Last edited by CHELLIE; 09-24-2009 at 09:14 PM.
CHELLIE is offline  
Old 09-24-2009, 07:35 PM
  #7  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

to attach the wing to the fuselages, glue a piece of plywood to the front part of the wing saddle, drill a hole in it, about 5/16" , drill into the front of the wing, in the middle where the wing meets the saddle, about 3/8" hole or what ever will work for you, drill in about 3" to 4" and epoxy in a 5/16" wood dowel, that will slip into the front wood saddle on both fuselages, leave about 3/4" sticking out of the wing, to mount the rear part of the wing, epoxy a piece of plywood, about 3/16" thick, about 3/4" wide ,flat at the rear saddle, drill a hole in it, in the middle, and use some 1/4" wood blind nuts, use 2 nylon 1/4" screws one for each fuselage to hold the wing down, drill 2 holes in the wing one for each fuselage, use a piece of thin plywood, 1/16" about 3/4" x 1" , drill a hole in the middle and glue to the wing bottom for a washer, so the bolts dont pull out of the wing, hope that helps, Chellie

Lots and Lots of great info here

http://www.airfieldmodels.com/inform...ruction/11.htm

http://www.airfieldmodels.com/inform...mple/index.htm

Last edited by CHELLIE; 09-24-2009 at 07:56 PM.
CHELLIE is offline  
Old 09-24-2009, 08:08 PM
  #8  
Cdr. Instigator
Pimp My Plane
 
Cdr. Instigator's Avatar
 
Join Date: Dec 2008
Location: Houston
Posts: 487
Default

D22, for vents you could look at what I did on my Funtana Clone

I found a neat trick that costs nothing but a trip to your local gas station..

Coffee Cup Lids self seal thingy maggigy..

http://www.wattflyer.com/forums/showthread.php?t=49914










You can see them installed looking from the inside as I was redoing the motor mount here..

Cdr. Instigator is offline  
Old 09-26-2009, 05:06 AM
  #9  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default Thanks, few more questions

Thanks Cdr. Instigator and CHELLIE

It helps a lot to hear from people with experience.

I was wondering what offset would you recommend?

Where can i get props that work for reversed motors?

and lastly...kinda a lengthy question.

If i have two motors and they pull slightly different Amps when run at the same throttle setting how strongly will this effect my planes performance?

I do not yet own a nice expensive watt meter so i just have to use the one i have... a Fluke 79 series multimeter...it maxes out at 10 Amp.

The way i tested my motors was i hooked them both up exactly the same one at a time and ran them at the full up trim setting with the throttle all all the way off. With a small prop one pulled 2.97Amp and the other 3.39Amp. At the same setting one provided 340g of thrust and the other 360g. How strongly will this effect me? Is there any way i can account for the difference and still use these motors?


Thank you very much for your help and time, I appreciate it very much,

D22av
d22av is offline  
Old 09-26-2009, 07:26 AM
  #10  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

reverse pitch props

http://www.modelflight.com.au/graupn...rs_reverse.htm

http://www.ecubedrc.com/shop/

http://www.hobbycity.com/hobbycity/s...idProduct=5249

http://www.hobbycity.com/hobbycity/s...wer_Search.asp

give the motors about 2 to 3 degrees of down thrust, if it was me, I would point both motors inward towards the center about 2 degrees, looking down from the top, point the r/s motor in towards the left, and point the left motor to the right about 2 degrees, something like toe in on a cars front wheels, start with straight no side thrust and then try the toe in to see it it makes the plane more stable, if it flies ok with the motors straight and no side thrust towards the center, then leave it alone

Buy one more motor, and see if you can get a better match between 2 of the 3 motors, they have to be as close as possible, not to much you can do, maybe change timing on one esc, dont know how much that will help, hope that helps, Chellie
CHELLIE is offline  
Old 09-26-2009, 07:46 PM
  #11  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default reverse pitch - Pusher -Counter Rotating - SAME THING?

Thanks for your response CHELLIE,

I talked to Jeff from Heads Up RC and he said that he'll match a pair up for

me. I can't wait to finish this model and start doing some testing with the

Thrust angles and getting it to fly strait. I am building the motor mount now and I'll post some

pictures once i finish.


Is a reverse pitch prop, Pusher prop, and Counter Rotating prop all the

same thing? Could i use any of them on the motor that will be rotating

clockwise? since typical motor/prop rotation is counterclockwise?


BTW thanks Cdr. Instigator for your air scoop idea. I think it looks really

good on your model and i will definitely be trying it out.

D22av
d22av is offline  
Old 09-26-2009, 07:54 PM
  #12  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

buy one package of each counter rotating/reverse pitch same thing, and reg 3 blade prop,

http://www.hobbycity.com/hobbycity/s...Prop_(2pc_pack)

http://www.hobbycity.com/hobbycity/s...er_Rotate_(2pc)





{{{ Is a reverse pitch prop, Pusher prop, and Counter Rotating prop all the

same thing? }}}} not sure on the pusher prop, i dont think they are the same as a reverse pitch and counter rotating prop.
CHELLIE is offline  
Old 09-27-2009, 03:13 AM
  #13  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default Quick question about Flaps

The F-82 Twin mustang has a single flap that comes down in between the two fuses.

I also decided to put one on my model.

The question is, should the flap move up and down like the aileron, just up and back to neutral, or just down and back to neutral.

What advantages/disadvantages do any of these choices provide?

Thanks everyone,

D22av
Attached Thumbnails Click image for larger version

Name:	P1030092.jpg
Views:	2165
Size:	615.7 KB
ID:	109994  
d22av is offline  
Old 09-27-2009, 03:38 AM
  #14  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

Originally Posted by d22av View Post
The F-82 Twin mustang has a single flap that comes down in between the two fuses.

I also decided to put one on my model.

The question is, should the flap move up and down like the aileron, just up and back to neutral, or just down and back to neutral.

What advantages/disadvantages do any of these choices provide?

Thanks everyone,

D22av
the flap in the middle can only be used to slow you down, if you use the flap to slow you down, it can only be used in one direction, Down, and only about 15 degrees of movement down, and IMHO only when you are landing to reduce speed, so it will need to be on a seperate transmitter switch and servo. just my 2 cents worth Take care, Chellie

PS. being that small, i dont think it will have very much affect, I could be wrong


CHELLIE is offline  
Old 09-28-2009, 07:52 AM
  #15  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default Finally finished the engine mount

So I finally fished building my engine mount. I decided to go with a combination of Cdr. Instigator's mount idea and another idea i saw on Chellie's thread about engine mounts. I did this because i liked the strength that Cdr. Instigator's mount had but i also wanted to be able to adjust my thrust angle after i test flew it. This is what i came up with.

Fell free to give me some input,
D22av
Attached Thumbnails Click image for larger version

Name:	2.jpg
Views:	179
Size:	485.2 KB
ID:	110110   Click image for larger version

Name:	3.jpg
Views:	195
Size:	595.4 KB
ID:	110111   Click image for larger version

Name:	4.jpg
Views:	208
Size:	550.6 KB
ID:	110112   Click image for larger version

Name:	5.jpg
Views:	190
Size:	483.7 KB
ID:	110113   Click image for larger version

Name:	6.jpg
Views:	193
Size:	69.4 KB
ID:	110114  

Click image for larger version

Name:	7.jpg
Views:	203
Size:	533.7 KB
ID:	110115   Click image for larger version

Name:	8.jpg
Views:	196
Size:	486.1 KB
ID:	110116   Click image for larger version

Name:	9.jpg
Views:	173
Size:	68.1 KB
ID:	110117   Click image for larger version

Name:	10.jpg
Views:	177
Size:	85.1 KB
ID:	110118   Click image for larger version

Name:	11.jpg
Views:	199
Size:	449.9 KB
ID:	110119  

Click image for larger version

Name:	12.jpg
Views:	188
Size:	461.4 KB
ID:	110120   Click image for larger version

Name:	13.jpg
Views:	199
Size:	463.4 KB
ID:	110121  
d22av is offline  
Old 09-28-2009, 08:12 AM
  #16  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

Originally Posted by d22av View Post
So I finally fished building my engine mount. I decided to go with a combination of Cdr. Instigator's mount idea and another idea i saw on Chellie's thread about engine mounts. I did this because i liked the strength that Cdr. Instigator's mount had but i also wanted to be able to adjust my thrust angle after i test flew it. This is what i came up with.

Fell free to give me some input,
D22av
PERFECT Thats as good as I could have done myself Take care and have fun, Chellie

I am going to be moving for the next few days, so i wont be posting to much if any, so see you as soon as i get settled in.
CHELLIE is offline  
Old 09-28-2009, 02:07 PM
  #17  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default

Thanks Chellie,

good luck moving.
d22av is offline  
Old 09-28-2009, 04:43 PM
  #18  
martin_05
Member
 
Join Date: May 2009
Posts: 143
Default

Originally Posted by d22av View Post
I do not yet own a nice expensive watt meter so i just have to use the one i have... a Fluke 79 series multimeter...it maxes out at 10 Amp.
No problem. You need a length of solid copper wire (the kind used to wire electrical power around the house). Here's the resistance in ohms per foot for different diameter wire:

10 .00118
12 .00187
14 .00297
16 .00473

You want a length that will give you one milliohm (0.001ohm). For example, if you are using 12ga. wire you need 6.4 inches. The formula is simple: Length = 12 x (0.001 / resistance-per-foot).

Then you make something like this:

Click image for larger version

Name:	IMG_0315[1].jpg
Views:	160
Size:	96.2 KB
ID:	110132

Click image for larger version

Name:	IMG_0316[1].jpg
Views:	144
Size:	100.0 KB
ID:	110133


Allow a little extra length beyond the calculated 0.001ohm length so you can get in and out of your connectors. I use Power Poles. Chances are you use Deans. Either is fine. In the case of Deans you need to put a male connector on the end that'll go to the battery and a female on the end that will go to the speed control.

BE CAREFUL as this current shunt exposes one voltage rail. You want to make sure that the other line is insulated (as you see in mine). It doesn't matter if you put the coil in the positive or negative side, BTW. Also, the only reason for coiling it is to make it shorter. You could leave it straight and it would work just as well. If you do decide to coil it make sure the loops don't touch. You will not blow anything up, even if all the coils are touching, but your measurements will not be accurate because the effective length will change due to the contact.

I marked my measurement points with a dab of solder. You could also take the time to shrink-tube over most of it and leave only enough room to get your voltmeter probes in.

You measure with your voltmeter set to the millivolts scale, say, 200mV full scale. This tool will give you a reading of one millivolt per Amp of current flowing through it. At 50A you'll read 50mV. If it reads negative and this bothers you just swap the voltmeter probes.

You could easily measure just about any current level most modellers run into using this approach. It helps to have alligator clips to connect it all together.

-Martin
martin_05 is offline  
Old 09-28-2009, 04:52 PM
  #19  
martin_05
Member
 
Join Date: May 2009
Posts: 143
Default

Originally Posted by d22av View Post
When deciding on how to create the airfoil I also ran into a small problem. HOW TO DO IT!


Stainless steel or nichrome wire stretched tight using a bow is the way to do it. You need a power supply that can provide the current (and the current control) to make this work. Search for "foam cutting bow" or something like that to get some ideas.


I decided to stick to the scale airfoil (minus the true scale thickness) and did some research.
Scale airfoils don't really work for model aircraft, particularly as they get smaller and smaller. I'd suggest that you search the 'net or the various fora to see what airfoils are being used with something like the P51 mustang and use that instead.

To cut the wing you make very accurate airfoil templates for each end of a wing section. You then attach (glue?) these templates to each end of a piece of foam. You have to make sure that they are located accurately in order to prevent any unwanted twist. One approach is to split the airfoil into two halves, upper and lower, so you can design-in a flat bottom section for alignment purposes. The templates would just rest on a flat table, which would align them auto-magically. You then run your hot wire over the template to cut out the wing section. A little practice is required to maintain a constant force and speed. If you vary the force you'll get defects in the surface. The rig I have uses a set of weights to pull at a relatively constant tension.

Key to the above is that you don't try to hand cut the foam to a precise size and shape. You want a basic rectangular block that is somewhat larger than the actual wing section. You let hot wire do all the cutting.

-Martin
martin_05 is offline  
Old 09-28-2009, 06:35 PM
  #20  
texasclouds
Super Contributor
 
texasclouds's Avatar
 
Join Date: Sep 2009
Location: Central Texas
Posts: 1,375
Default

wow, that looks great. i hope she flies for you.
texasclouds is offline  
Old 09-28-2009, 07:04 PM
  #21  
martin_05
Member
 
Join Date: May 2009
Posts: 143
Default

Originally Posted by martin_05 View Post
[/FONT]

Stainless steel or nichrome wire stretched tight using a bow
I think that's iconel rather than nichrome. Have to check...it's been a while since I've had to build a new bow.

-Martin
martin_05 is offline  
Old 09-29-2009, 07:43 PM
  #22  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default Thanks - Question about retracts

I was considering putting retracts on this model haven't really seen many models that are this small with retracts. Anyone have any ideas?
Would it be OK to just have the wheels come up to the bottom of the wing but not go inside...my wing is only about 1" thick at the thickest part.



Originally Posted by texasclouds View Post
wow, that looks great. i hope she flies for you.
Yea...with all the time I'm spending on it i really hope it does too.


martin_05, thanks a lot i had no idea you could do that. I will definitely be making something like that. A 55$ watt meter designed for RC is just something i can't afford right now.

I did end up sing an airfoil very similar to the p-51 mustang. Hopefully it will fly.
d22av is offline  
Old 10-02-2009, 04:22 PM
  #23  
d22av
New Member
Thread Starter
 
Join Date: Aug 2009
Location: Boston, MA
Posts: 15
Default Question about control throws

I've been searching online for a similar plane to find out what control throws to use but haven't been able to find anything. Does anyone have any advice?

Thanks a lot
d22av is offline  
Old 10-08-2009, 07:19 AM
  #24  
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 19,262
Default

Originally Posted by d22av View Post
I've been searching online for a similar plane to find out what control throws to use but haven't been able to find anything. Does anyone have any advice?

Thanks a lot
Hi, I would use 3/8" up and 3/8" down from neutral, on the ailerons and elevator for a total of 3/4", i would use 1/2" from from neutral on the rudder for a total of 1" , and i would put the CG at 25% back from the main wing leading edge, just my 2 cents worth, Hope that helps, Take care, Chellie
CHELLIE is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Urbangorilla
Scale E-Powered Aircraft
9
02-10-2015 09:20 PM
Urbangorilla
Warbird Electrics
18
03-05-2009 07:58 PM
Milton
Motors and Speed Controllers for sale & WTB
0
11-19-2006 06:08 AM
FlightMedic
Warbird Electrics
4
11-06-2006 03:08 PM
admin
Off Topic Chit Chat
0
07-24-2005 10:28 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Quick Reply: F-82 Twin Mustang!!!! With Pics


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.22309 seconds with 52 queries