If you are building a KFm2 or KFm3 wing, a wing width (one piece for each wing half) 1/4" x 1/2" spar made from spruce, basswood, or almost any other light wood will give you all the stiffness needed for the span of the wing and it won't add more than 10 grams or so to a 33" wing.

The spar works very well glued with the 1/2" edge vertical at the back edge of the front KFm strip. I use 5 minute epoxy to mount the spar on the top of the wing bottom as a first step. Subtract the 1/4" thickness of the spar from the KFm strip to keep the dimensions right.

If you add another (not on the plans) short strip of foam 1/2" or so long in front of the spar, and glue that in place as the KFm strip is folded back and glued, allowing the KFm strip to be flush with the top of the spar, the foaming action of the PU glue will fill the small gaps above the short strip and below the KFm strip, and give you a very rigid wing.

For the center joint, I used the method described by tony65x55 (The Blu-Baby Genius Himself) for building the center joint. I do it as follows:

1 - Sand to get the dihedral right and edges of the butt joint well matched. The wood spars are butted together, there is no overlap or dihedral brace. In the photos below, the spars were left a little short but I'd bring them into contact at the joint on the next wing.

2 - Lay a strip (a little more than twice as long as the chord, 18" or so) of clear duct tape sticky side up on the bench and tape one end down.

3- Lay the two wing halves flat on the tape just touching at the dihedral joint, get the tape well adhered to the bottom of the wing.

4 - Spritz the joint with water or apply some with a small brush and then apply the PU. I put PU on both wing roots and also allow it to dribble into the hollows and openings. Not a tremendous amount but all meeting surfaces well coated.

5 - Prop one wing up to get the total dihedral (i.e., 4" inch block for 2" per side).

6 - Use a paper towel to dab up any excess water on the top of the wing, then fold the duct tape up and over the trailing edge for about 1" or so and cut it off. Then fold the duct tape back from the leading edge to the back edge of the trailing edge, following the steps as you go.

7 - In 5 to 10 minutes you'll see the foaming action at work and you can gently press the foaming glue flat and back into the wing with a soft squeegee or your finger (pushing on the tape). Let it build up a little on the centerline and it will form a nice gently blended joint.

8 - After 15-20 minutes, very gently pick the wing up and check the bottom joint. A little squeegee work there will flatten out any foam and get the tape flat again.

9 - Put it back on the bench with one wing flat and the other blocked up and let it set overnight.

When it is all dry, you can smooth any exposed and hardened PU foam with 80 grit or so sandpaper. Or you can just ignore it. Just hit the high spots, be careful of the bare foam as it will disappear real quick with sandpaper. I use 150 grit sandpaper for any final smoothing and shaping of foam.

Add tongue depressors to the leading and trailing edges where the rubber bands go over the edges. I score three or four adjacent shallow grooves in the center of the leading edge stick with a razor saw so it will bend easily to match the dihedral and then put it on with hot glue. On the trailing edge, I trim the stick to match the taper of the wings after the it is glued in place.

The wing seen below survived the demolishment of my first BB 33 fusleage, now has ailerons, and is being further tested on my new Industrial Strength BB 33. I'm more about strong than I am about light. Strength in construction is essential to sustaining my flying earning curve.

Jack

jackerbes

Excellent tutorial.

Mike

Originally Posted by dz1sfb

Aranel,

Your BB should still fly fine at 10.5 oz. Is that the cross weave reinforcement tape you have on the wing? If it is I know that stuff needs to be used judiciously. Kind of heavy stuff. I built a KFm2 for a 33 incher and wrapped the LE and center section and the wing was heavier than the UC with full dowel rods and clear packing tape and paint.

Ken

Yes that is reinforcement tape along the front and back. I hot glued the dowel rod in spots after steaming the middle. Then I wrapped the whole leading edge again. It is plenty strong now!

I flew again tonight and didn't notice any adverse weight issues. I flew two packs and kept on getting more and more happy with this plane. Large loops and hammerheads look really nice. Doesn't like inverted though. Probably because that is not what it was designed for huh.

The blue wonder and 9*7 prop worked really well. I just cruised around the sky at 1/4 to 1/2 throttle. I just bought another one from lazertoys http://www.ncweb.com/biz/dan/Motors.html - its the BLUE WONDER 24 gram Brushless 2712-12 combo with esc for $27.50. A good deal I think.

I'm really thinking about building floats for this plane. I have never flown off of water before and it sounds fun. Has anyone recently tried this? I thought I saw some plans for floats somewhere in this thread.... Also any advice on this would be greatly appreciated.

Aranel

Another "Multi-Pack" flier. I have 3 2s packs that work in the BB33 and I have flown all three many times. Actually I managed to fly 5 packs threw it at a family get together a while back. The plane just loves to fly. A total of 6 people took the sticks that day and all were impressed. I had to tell them that they should not expect that if they go buy a plane at an LHS. The BB is just special.

Rob...

do you guys use any plywood to attach landing gear or somewhere else?
I have 1 mm plywood and I was thinking i could make my BBAP even stronger.

Originally Posted by Cristian23

do you guys use any plywood to attach landing gear or somewhere else?
I have 1 mm plywood and I was thinking i could make my BBAP even stronger.

I use it for the firewall/motormont. M ine is 1/32" or 0.8mm. I use single layer for small motors such as the 10gr on the BB-24 and 2 layers glued together cross grain for larger motors as on a BB-33. I never had a motor come loose from the wood.
Ripped the foam out with the wood and motor still attached twice.

I have also used it to to reenforce the battery box on the BB-33.
See the pic.

Mike

manged to get out this evening for a quick flight heres a link to the video https://www.rcgroups.com/forums/show...6#post10620319

bbap looses a prop (0 min 51 sec)

hey guys- ive got the feuse built today for a 33in using 2" monoblock.,
i want to go with a kfm wing and skip the fragile uc wing. prob a kfm3 with no dihedral for alerons. i dont quite have a grasp on how to build the kfm.
it looks like the le of wing is suposed to be made in the fold of the fff. can i build the whole wing as 1 assy vs 2 halves?
how bout the set up for the servo(s)
pics would be great as i learn better bu sight
thanks bondo

Originally Posted by mxspode

Another "Multi-Pack" flier. I have 3 2s packs that work in the BB33 and I have flown all three many times. Actually I managed to fly 5 packs threw it at a family get together a while back. The plane just loves to fly. A total of 6 people took the sticks that day and all were impressed. I had to tell them that they should not expect that if they go buy a plane at an LHS. The BB is just special.

Rob...

Excellent story about the family gathering! It's good to hear bb's influence is still strong and bringing more ppl closer to our hobby. Sorry for the cliche, but the old "sometimes if you want something done right, you just have to do it yourself" applies to the BB... unless of course you have someone else build a bb for you.

kev

Originally Posted by bondohead

can i build the whole wing as 1 assy vs 2 halves?
how bout the set up for the servo(s)

Absolutely, I would definitely build the wing 1pc. It's way stronger and lighter that way. I say go for it if your foam is big enough and you're going without dihedral. For the servo(s): what size are you building? Do you have 2-servo aileron mixing on your TX? What kind of servo, how many you need, and how they get wired up depends on the answers to those 2 questions.

kev

so if i am rigt the 40 52 and 60 use same fuse? bbap1?

i found a great thing on kfm wings with good pictures here it is http://www.ncflyingtigers.org/combat...%20Study21.pdf

"..can i build the whole wing as 1 assy vs 2 halves?..."

If you build a flat wing, yes. If you want dihedral, you have to build in two halves to get the KFm strips aligned at the center since you cannot do any complex or compound bends with the foam.

Look at the example I posted just above at:

https://www.rcgroups.com/forums/show...postcount=7921

That is a KFm3 wing for a 33 and was built with 3/4" dihedral. I added the ailerons to it later putting them in pockets in the foam on the top of the wing as seen in the photo below. That method is pretty hard to beat for short, simple linkages. On that plane I ran the servo leads to the back of the wing and down into the fuselage.

I found the KFm3 with 3/4" dihedral and ailerons to be a bit much for my present skill levels. It was pretty fast and *very* responsive. My son, who is is a very good flyer, really liked it but admitted that it was probably a handful for me at my present skill level.

I'm still working on getting my "heavy thumbs" tamed down so I am now flying that same fuselage with a KFm2 wing with 2" of dihedral and no ailerons. I got about 30 minutes of air time with that today and it is the perfect plane for me right now.

My BB 33 is sort of a departure from the norm, I call it the Industrial Strength BB 33. It is a little more crashproof and also heavier than most of them at 21.9 oz. ready to fly. You can see the details on it at this post:

https://www.rcgroups.com/forums/show...postcount=7793

Jack

Truglodite- building a 33"
htx 9g servos
no mixing on my basic tx
justwanafly- thx for the link. still cant tell from pic if the front(le) is made of one peace of folded foam?

could some of you guys post some pics of your bb's for me?
thanks bondo

jackerbes- i looked at your pics but couldnt tell if the sandwich is all one peace or not
how does the dihedral work with alerons? past exp hasnt ben so good w/ that set up
3/4 in with one side flat on table other wing tip 3/4"in the air?

Originally Posted by bondohead

Truglodite- building a 33"
htx 9g servos
no mixing on my basic tx
justwanafly- thx for the link. still cant tell from pic if the front(le) is made of one peace of folded foam?

could some of you guys post some pics of your bb's for me?
thanks bondo

You may not like the sound of this BUT, I highly recommend putting your project on hold for a day or so, and reading this ENTIRE thread, all 500+ pages of it. It was in the mid 400's when I did it. Tons of questions I had got an "OHHHHHHH" and there were also moments where I thought "I never thought of that, glad I read it!" You'll do a lot of skimming, but try to digg through as much as tyou can, its a massive bank of knowledge.

gren- you are probably right! ive ben a part of this thred mostly following through the summer but not posting scene i wasnt redy to build and didnt have any thing to contribute. i have red 1/2 of it but it is overwhelming to go back over 8000 posts
im so close to haveing my bird dog bb in the air, im impatient.
sorry!

Originally Posted by Truglodite

Excellent story about the family gathering! It's good to hear bb's influence is still strong and bringing more ppl closer to our hobby. Sorry for the cliche, but the old "sometimes if you want something done right, you just have to do it yourself" applies to the BB... unless of course you have someone else build a bb for you.

kev

I have built four now. I only have one. All of the extra ones were requested after allowing a total novice to take the sticks. The family gathering only resulted in one request but at least three other maybes (cost of all of the additional items concerns). Frankly I enjoy building as much as flying so it works out great and it has made me a bit of a star with all of the kids. The youngest to fly at that event was four. Lasted for almost a minute before she over compensated due to her dad telling her "PULL UP" in a turn. No damage done and I told her she could do it again next time. I really need to get a second TX for buddy box flying.

Rob...

no bondo it is 2 pieces glued together and sanded to almost a point more of a round surface i hope it helps

the easiest way i could explain how to make one like the guy did on my link. Would be cut out your pieces take the first kfm piece match it with the leading edge.Then draw a line where the back of the kfm piece is.now that line will be the back of your 1/4x1/4 basswood glue it down.then glue your first kfm piece to your leading edge and on top of your basswood then take your 2 kfm piece and bump it against the basswood and glue it down.. then add your alirons..its that easy i was fighting with this too till my link

bondohead,

The wing wing halves are built up from three pieces of foam. The bottom piece is flat, the front KFm strip folds back and rests on the spar, and the back KFm strip is behind the spar.

Have you looked at the plans and the other stuff there?

The basic plans are here on the first page:

https://www.rcgroups.com/forums/show...80&postcount=1

The 42 to 60 inch variants and the AP model are here:

https://www.rcgroups.com/forums/show...&postcount=107

The 2" monobloc parts are here:

https://www.rcgroups.com/forums/show...1&postcount=37

And you definitely want to use a 2" monobloc, the 1" model is very cramped and hard to work in.

The info on the 33" KFm3 wing is at this post:

https://www.rcgroups.com/forums/show...&postcount=140

and that includes some stuff that will show you how to put the wing together, that is in the KFm Wing Fold Instructions.pdf at the last link.

There are also some *.pdf files with studies and tech info on the wings, I can't seem to put my finger on them now as they are somewhere in the earlier posts.

What most of us did was get the plans "tiled" into pages so we could cut them up and tape them together to make templates for the parts. Then we cut out the parts and started learning the hard way from the other posts or by asking questions here.

It was a little bit of a challenge getting started but worth the effort.

Jack

jackerbes the kfm wing fold pdf is exactly what i was looking for! i didnt even know there was 2" parts plans. i just used the plans in the first post to make my feuse and mono block just used 2" insted of 1". then after feuse and block assembled measured the with and mod the top and bottem plans to sute.
thanks for the links
mx im building another stc for a beginner due to its simpler/faster build. also lighter so it will slow down as to give a noob that extra time to figure out wich way to move the sticks. havent seen a bb fly yet, how do the beginners do on it?
tony -
you should move the 2" parts and the wing fold diagram to the 1st post with the other plans. oh yea, thanks a million for your contribution to the scratch build forum, all your time/posts and the plans! i have noted you keep up on this thread and pay attention to every post like no one ive ever seen. i thank and admire your dedication to your creation. your BLUE BABY
thanks
bondo

Had a great afternoon flying our babies at Stoney Creek. Three 24's with combination of uc, kfm2, kfm3 and kfm3 w/ailerons. Wings flying all over. Having too much fun flying to take pix, but did get one with phonecam. This is one confident flier, and multitasker! No, he's not talking to the plane, and I don't think it was his wife, either; sounded like a work call. Seconds before, Ken was making his dayglo baby dance, but he did settle it down a bit while on the phone.

Originally Posted by justwanttofly

so if i am rigt the 40 52 and 60 use same fuse? bbap1?

No, that is not correct. The BB42 uses a different fuse from the 52" ad 60", which use the BBAP1 fuse.

Tony

Originally Posted by bondohead

jackerbes the kfm wing fold pdf is exactly what i was looking for! i didnt even know there was 2" parts plans. i just used the plans in the first post to make my feuse and mono block just used 2" insted of 1". then after feuse and block assembled measured the with and mod the top and bottem plans to sute.
thanks for the links
mx im building another stc for a beginner due to its simpler/faster build. also lighter so it will slow down as to give a noob that extra time to figure out wich way to move the sticks. havent seen a bb fly yet, how do the beginners do on it?
tony -
you should move the 2" parts and the wing fold diagram to the 1st post with the other plans. oh yea, thanks a million for your contribution to the scratch build forum, all your time/posts and the plans! i have noted you keep up on this thread and pay attention to every post like no one ive ever seen. i thank and admire your dedication to your creation. your BLUE BABY
thanks
bondo

2" Monobloc parts plan is now posted on Page 1, post 1. Good suggestion. Thanks for the kind words. It's a labour of love.

Tony

thanks tony ya i seen that later im going to build a 24 for a buddy of mine and a 60 for me =)

Originally Posted by springer

Had a great afternoon flying our babies at Stoney Creek. Three 24's with combination of uc, kfm2, kfm3 and kfm3 w/ailerons. Wings flying all over. Having too much fun flying to take pix, but did get one with phonecam. This is one confident flier, and multitasker! No, he's not talking to the plane, and I don't think it was his wife, either; sounded like a work call. Seconds before, Ken was making his dayglo baby dance, but he did settle it down a bit while on the phone.

LOL!!!

Originally Posted by justwanttofly

thanks tony ya i seen that later im going to build a 24 for a buddy of mine and a 60 for me =)

After you see that little 24" scoot you'll be building two.

Tony,

You're a busy guy and I love you for what you've done here. I'm getting a lot of enjoyment out of building and flying (or trying to fly at least) and the Blu-Baby gets credit for getting that started.

I sort of wonder it there could not be a sticky (or something like that?) at the start that has every one of the *.pdf files with plans and info. I can usually find them to post links to them for the newbies but it would be easier to have them all in one place.

Thank you again!

Jack

Originally Posted by bondohead

mx im building another stc for a beginner due to its simpler/faster build. also lighter so it will slow down as to give a noob that extra time to figure out wich way to move the sticks. havent seen a bb fly yet, how do the beginners do on it?

My BB33 with the Under Camber wing Flies incredibly soft and easy. Only once have I handed the TX to a novice flier and had them bring the plane immediately down. This was due to them doing the one thing I tell them not to, open up the throttle. All others have been able to fly relatively well and do basic turns and transitions to level flight by simply listening to my directions. The BB is very forgiving and at sufficient throttle setting nearly stall proof. It is hard to mess up on and if you do mess up the plane flies so slow that you have plenty of time to save it. My plane will self correct nearly all bad situations , given sufficient altitude by simply letting go of the sticks. If you set it up properly and get the right power and the CG worked out you won't believe how well it flies. Mine does scale like ROG take offs and can be landed fairly easily if the wind isn't to strong.

Watch your setup during construction, follow proper pre-flight procedures and you will Love this plane.

Rob...