Joining foam wings
05-07-2010 | 12:52 PM
#1
Joining foam wings
Hi all,
I have a general question as we see many ARF planes most of them have built up wing so joining the wings is usual as we all know. My problem is if i have to manufacture ARF with a foam wing what will be the best way to join the two wings what will be the best way to make it strong & straight forward. The wings are veneer sheeted. I have been thinking about this for quite long time so i thought to post it here & know what will be the best solution for this problem.
Thanks in advance,
High..
I have a general question as we see many ARF planes most of them have built up wing so joining the wings is usual as we all know. My problem is if i have to manufacture ARF with a foam wing what will be the best way to join the two wings what will be the best way to make it strong & straight forward. The wings are veneer sheeted. I have been thinking about this for quite long time so i thought to post it here & know what will be the best solution for this problem.
Thanks in advance,
High..
05-07-2010 | 03:16 PM
#3
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RE: Joining foam wings
The way I have been joing foam wings over the years is butt joining them with 30 min epoxy after first sheeting the wing cores. Then I apply heavy fiber glass tape 4 inches wide around the joint, again with 30 min epoxy. I have used this with 40 and 60 size wings without failure.
Bruce
Bruce
05-07-2010 | 06:41 PM
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From: Orange,
NJ
RE: Joining foam wings
How thick are the wings and how big ? Reason I ask is if the wing is about 1 inch or thinner and it would be on a fast plane , it would help to cut in a spar across the center or what we use to do on quickie wings, cut in 1/4 inch dowel channels top and bottom along the high point of the wing each side from tip to tip. Slide in the dowels into the channels then sheet the wing. Epoxy the wings together using 30 min . When dry glue on the fiberglass cloth in the center. We used 6 inch wide because of the high stress.
Note we used regular hard wood dowels my flying buddy and I. Some people used Dave Brown carbon rods instead of dowels or even carbon fiber thread or tape also from Dave brown . The thread was glued onto the foam high point ,top and bottom. Good thing about using the thread you don`t have to make channels in the foam. How its done is you coat the wing with 30 min epoxy if you are experience in doing this method , lay the thread along the high point , brush it down then lay your balsa sheets over it. You do both sides lay the wing back in its cradle and put weights on top . Each wing half is done then glue halves together and glass center . Pros of this method , wing is very strong . Depends how big the wing is determine how wide the carbon thread you use, example our wingspan would be about 52 to 54 inch 9inch cord.and used 1/2 in wide thread or carbon tape. No channel to make. Cons...you use a lot of epoxy.
Yep those were the days nothing but hot Fox , MDS , Thunder Tiger 40s boring holes in the sky.
Note though if for regular sport flying, no need for spars . just sheet wing halves glue together with epoxy and glass the middle. You must glass the middle or it will break in flight. Don`t think it will next time you go driving stick your hand out the window at 50 miles an hour. Feel that pressure on your hand ? That will break the wing.
Note we used regular hard wood dowels my flying buddy and I. Some people used Dave Brown carbon rods instead of dowels or even carbon fiber thread or tape also from Dave brown . The thread was glued onto the foam high point ,top and bottom. Good thing about using the thread you don`t have to make channels in the foam. How its done is you coat the wing with 30 min epoxy if you are experience in doing this method , lay the thread along the high point , brush it down then lay your balsa sheets over it. You do both sides lay the wing back in its cradle and put weights on top . Each wing half is done then glue halves together and glass center . Pros of this method , wing is very strong . Depends how big the wing is determine how wide the carbon thread you use, example our wingspan would be about 52 to 54 inch 9inch cord.and used 1/2 in wide thread or carbon tape. No channel to make. Cons...you use a lot of epoxy.
Yep those were the days nothing but hot Fox , MDS , Thunder Tiger 40s boring holes in the sky.
Note though if for regular sport flying, no need for spars . just sheet wing halves glue together with epoxy and glass the middle. You must glass the middle or it will break in flight. Don`t think it will next time you go driving stick your hand out the window at 50 miles an hour. Feel that pressure on your hand ? That will break the wing.
05-07-2010 | 11:19 PM
#6
RE: Joining foam wings
ORIGINAL: 91zulu
How thick are the wings and how big ? Reason I ask is if the wing is about 1 inch or thinner and it would be on a fast plane , it would help to cut in a spar across the center or what we use to do on quickie wings, cut in 1/4 inch dowel channels top and bottom along the high point of the wing each side from tip to tip. Slide in the dowels into the channels then sheet the wing. Epoxy the wings together using 30 min . When dry glue on the fiberglass cloth in the center. We used 6 inch wide because of the high stress.
Note we used regular hard wood dowels my flying buddy and I. Some people used Dave Brown carbon rods instead of dowels or even carbon fiber thread or tape also from Dave brown . The thread was glued onto the foam high point ,top and bottom. Good thing about using the thread you don`t have to make channels in the foam. How its done is you coat the wing with 30 min epoxy if you are experience in doing this method , lay the thread along the high point , brush it down then lay your balsa sheets over it. You do both sides lay the wing back in its cradle and put weights on top . Each wing half is done then glue halves together and glass center . Pros of this method , wing is very strong . Depends how big the wing is determine how wide the carbon thread you use, example our wingspan would be about 52 to 54 inch 9inch cord.and used 1/2 in wide thread or carbon tape. No channel to make. Cons...you use a lot of epoxy.
Yep those were the days nothing but hot Fox , MDS , Thunder Tiger 40s boring holes in the sky.
Note though if for regular sport flying, no need for spars . just sheet wing halves glue together with epoxy and glass the middle. You must glass the middle or it will break in flight. Don`t think it will next time you go driving stick your hand out the window at 50 miles an hour. Feel that pressure on your hand ? That will break the wing.
How thick are the wings and how big ? Reason I ask is if the wing is about 1 inch or thinner and it would be on a fast plane , it would help to cut in a spar across the center or what we use to do on quickie wings, cut in 1/4 inch dowel channels top and bottom along the high point of the wing each side from tip to tip. Slide in the dowels into the channels then sheet the wing. Epoxy the wings together using 30 min . When dry glue on the fiberglass cloth in the center. We used 6 inch wide because of the high stress.
Note we used regular hard wood dowels my flying buddy and I. Some people used Dave Brown carbon rods instead of dowels or even carbon fiber thread or tape also from Dave brown . The thread was glued onto the foam high point ,top and bottom. Good thing about using the thread you don`t have to make channels in the foam. How its done is you coat the wing with 30 min epoxy if you are experience in doing this method , lay the thread along the high point , brush it down then lay your balsa sheets over it. You do both sides lay the wing back in its cradle and put weights on top . Each wing half is done then glue halves together and glass center . Pros of this method , wing is very strong . Depends how big the wing is determine how wide the carbon thread you use, example our wingspan would be about 52 to 54 inch 9inch cord.and used 1/2 in wide thread or carbon tape. No channel to make. Cons...you use a lot of epoxy.
Yep those were the days nothing but hot Fox , MDS , Thunder Tiger 40s boring holes in the sky.
Note though if for regular sport flying, no need for spars . just sheet wing halves glue together with epoxy and glass the middle. You must glass the middle or it will break in flight. Don`t think it will next time you go driving stick your hand out the window at 50 miles an hour. Feel that pressure on your hand ? That will break the wing.
many thanks for the detail explanation... thats exactly what i was thinking of using spars in the foam wing from top to bottom. The wings are of standard 40 size trainer & some other sport planes I am building it as a ARF.
I am not using BALSA to sheet the wing i am using veneer for sheeting as this material is very thin i prefer to use a spar.
To explain my challenge... if this is a ARF models wings are ready covered in ready 2 piece how will one join the wings together ????? this was my main question that i posted i have thought of a idea i will make a drawing of it & post it here... by today but i would like to know some ideas from you.
I am doing this to manufacture a few ARF planes.. its in a R&D process.
Thanks in advance,
High
05-08-2010 | 12:37 AM
#7
RE: Joining foam wings
Please see the attached picture of the idea i have to make a foam wing joiner like a ARF model. This idea is only for ARF planes i wish to manufacture. As i have mentioned i don't want to go with the built up wing, i will be veneer foam, any comments & ideas are welcome.
Thanks,
High
Thanks,
High
05-08-2010 | 06:38 PM
#8
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From: Orange,
NJ
RE: Joining foam wings
For the planes you will be flying all you need to do is butt glue the two wings together using epoxy or wood glue. The only reason to cut in spars was if the planes would be use for high speed flying over 100 mph. Most sport flying is way below that. more in the 60 / 70 mph range . So for your kind of flying you don `t have to worry about cutting in spars in your wings even with veneer skins. After you glue the wings together and it is dry use 4 inch wide 1 oz fiberglass cloth and using epoxy, glue the cloth over the joint, leading edge to trailing top and bottom. First light sand the center joint , then mix some 30 min epoxy. Add a little alcohol to thin it out to about the consistency of water . Lay the cloth nice and flat over the joint and pour the epoxy onto the glass. Use a brush to spread the epoxy from center out to the edge of the glass cloth. Don`t saturate the glass too much. Use just enough epoxy to lay the glass down. Do bottom first then top, so that the top glass over lap the bottom about 1/4 inch . When you glass the bottom bring the glass right to the leading edge where it start to curve, and trailing edge over lap about 1/4 inch off the edge. Same with the top. Lay the top glass 1/4 inch over where the bottom stop. The trailing edge over laps you will cut after the glue is set. You can do a second coat when the epoxy is about half way dry. The second coat is to cover the weave and feather the edge of the glass. Add less alcohol this time. Note when you add alcohol to epoxy it sets quicker. So the first batch probably will start setting after about 15 mins depending how much alcohol you add. Let the wing set over night or 3 hours if doing it during the day. Sand the joint with 320 sand paper and get rid of the ridge at the end of the glass if any. You may want to lay some masking tape along the edge of the glass before you sand so as not to sand into the veneer skin. Then just cover the wing the way you want to , Fabric or plastic film. That `s how its done for sport flying no need for spars. For that type of flying the wing will be plenty strong.
05-09-2010 | 02:23 AM
#9
RE: Joining foam wings
ORIGINAL: 91zulu
For the planes you will be flying all you need to do is butt glue the two wings together using epoxy or wood glue. The only reason to cut in spars was if the planes would be use for high speed flying over 100 mph. Most sport flying is way below that. more in the 60 / 70 mph range . So for your kind of flying you don `t have to worry about cutting in spars in your wings even with veneer skins. After you glue the wings together and it is dry use 4 inch wide 1 oz fiberglass cloth and using epoxy, glue the cloth over the joint, leading edge to trailing top and bottom. First light sand the center joint , then mix some 30 min epoxy. Add a little alcohol to thin it out to about the consistency of water . Lay the cloth nice and flat over the joint and pour the epoxy onto the glass. Use a brush to spread the epoxy from center out to the edge of the glass cloth. Don`t saturate the glass too much. Use just enough epoxy to lay the glass down. Do bottom first then top, so that the top glass over lap the bottom about 1/4 inch . When you glass the bottom bring the glass right to the leading edge where it start to curve, and trailing edge over lap about 1/4 inch off the edge. Same with the top. Lay the top glass 1/4 inch over where the bottom stop. The trailing edge over laps you will cut after the glue is set. You can do a second coat when the epoxy is about half way dry. The second coat is to cover the weave and feather the edge of the glass. Add less alcohol this time. Note when you add alcohol to epoxy it sets quicker. So the first batch probably will start setting after about 15 mins depending how much alcohol you add. Let the wing set over night or 3 hours if doing it during the day. Sand the joint with 320 sand paper and get rid of the ridge at the end of the glass if any. You may want to lay some masking tape along the edge of the glass before you sand so as not to sand into the veneer skin. Then just cover the wing the way you want to , Fabric or plastic film. That `s how its done for sport flying no need for spars. For that type of flying the wing will be plenty strong.
For the planes you will be flying all you need to do is butt glue the two wings together using epoxy or wood glue. The only reason to cut in spars was if the planes would be use for high speed flying over 100 mph. Most sport flying is way below that. more in the 60 / 70 mph range . So for your kind of flying you don `t have to worry about cutting in spars in your wings even with veneer skins. After you glue the wings together and it is dry use 4 inch wide 1 oz fiberglass cloth and using epoxy, glue the cloth over the joint, leading edge to trailing top and bottom. First light sand the center joint , then mix some 30 min epoxy. Add a little alcohol to thin it out to about the consistency of water . Lay the cloth nice and flat over the joint and pour the epoxy onto the glass. Use a brush to spread the epoxy from center out to the edge of the glass cloth. Don`t saturate the glass too much. Use just enough epoxy to lay the glass down. Do bottom first then top, so that the top glass over lap the bottom about 1/4 inch . When you glass the bottom bring the glass right to the leading edge where it start to curve, and trailing edge over lap about 1/4 inch off the edge. Same with the top. Lay the top glass 1/4 inch over where the bottom stop. The trailing edge over laps you will cut after the glue is set. You can do a second coat when the epoxy is about half way dry. The second coat is to cover the weave and feather the edge of the glass. Add less alcohol this time. Note when you add alcohol to epoxy it sets quicker. So the first batch probably will start setting after about 15 mins depending how much alcohol you add. Let the wing set over night or 3 hours if doing it during the day. Sand the joint with 320 sand paper and get rid of the ridge at the end of the glass if any. You may want to lay some masking tape along the edge of the glass before you sand so as not to sand into the veneer skin. Then just cover the wing the way you want to , Fabric or plastic film. That `s how its done for sport flying no need for spars. For that type of flying the wing will be plenty strong.
Thanks for the details...
Like i said i am manufacturing a ARF plane & the model will be pre covered like a sample picture i have attached of a trainer model the attached picture has a built up wing but i a building a foam wing covered with veneer & the wings will be ready covered so there is no point to fiber glass the wing at the center like i have attached the previous image how the wing joiner will work please see attached image...
I hope you understand my question... this model will be a ARF complete ready covered just join the wings & fly........
Thanks,
High
05-09-2010 | 01:39 PM
#10
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From: Orange,
NJ
RE: Joining foam wings
Ok are you saying when you build your foam wings you want to use wood joiners like the ARF built up wings use ? If your answer is yes. then you would have to cut slots in both halves the length of the joiner . Just make sure the wood grain runs length wise not up and down or it will break in the center. You could use l/8 light ply about 10 to 12 inch long and what I would do is cut the slots 6 inch each half before you put on the veneer skins. Do a dry fit slide the joiner in place and put the wings together making sure its a snug fit. After you are satisfied with the fit sheet the wings with the veneer making sure no glue get into the slots. After the skins are dry slide in the joiner do a dry fit again to make sure the 2 wing halves fit nice together . take apart and I would use Gorilla glue in the slots to glue the joiner. The gorilla glue expands and would fill any voids in the foam. The amount you use depends on how snug the joiner fit. If its snug just a thin coat of glue on the joiner , spray a little water in the slots. Do one side and slide the joiner in place to the half way point. don`t forget to mark this on the joiner. Then put epoxy in the middle surface of the wings and slide the other wing half on. Wipe away all glue oozing out and tape wings together with masking tape to keep it straight. I use wide tape for this . Along the joint top and bottom and across the joint. Hope this helps.
Note you do the same for wings with dihedral . You just have the cut the angle in the joiner and also the foam wings.
Note you do the same for wings with dihedral . You just have the cut the angle in the joiner and also the foam wings.
