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Old May 02, 2010, 07:33 PM
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Cherry Hill, NJ
Joined Sep 2009
54 Posts
Building light and strong with Readi-Board

I love building with Readi-Board, but I don't like how flimsy the tail section feels without some kind of stiffener. On the original build of BB Beta, I added a second layer of Readi-Board on each side between the rear of the monobloc and the front of the horizontal stabilizer slot. This worked very well for eliminating "tail wag" every time I activated the servos, but the horizontal and vertical stabilizers were still too "flexy" for my tastes.

After the first crash of BB Beta, I replaced the single-layer control surfaces with parts made from doubled-up Readi-Board. That made the whole tail rigid enough, but also added weight to the tail.

On BB Gamma, I hit upon an idea that allows for strength, low weight, and a way to add hinges that I think is better than using packing tape.

I put my Dremel tool in a router attachment and used a flat-ended cutting bit to mill out pockets in the horizontal and vertical stabilizer halves before gluing them together, and in the doubled-up sections of the body sides after the stiffeners were glued on but before the body was assembled.

The pockets in the control surface halves are about 1/8" deep and those in the body halves go all the way through the inner layer. I left 1/2" of full thickness material along the perimeter of all pieces and kept some full thickness "braces" in the middle of the pieces.

As for the hinges -- I have a few overhead transparencies lying around. Because I'll never again use them for their original purpose, I decided to put them to use as hinge material. I cut a few 1/2" X 1" pieces of transparency, then cut matching slots at the glue lines in the doubled-up control surfaces. I glued the hinges into the elevator and rudder first -- using hot glue and masking off the foam with tape. Then I used the same technique to join the tail pieces together.

Unlike packing tape hinges, these ones stay tight and aligned. The glue line makes it easy to ensure that the hinges are exactly half way between the left and right of the rudder and top and bottom of the elevator.

I'll be building BB Delta soon (probably an Oshkosh Special) using these techniques. I promise to take pictures as I build it and post them here, so you can get a better idea of what I've done.

Now if I can only find a way to get the servos and control horns lined up without cutting large "trial and error" holes on the fuselage, I'll have good solutions to all my most vexing construction issues.

Cheers!

Kevin
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Old May 02, 2010, 11:17 PM
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Canada, BC, Williams Lake
Joined Jan 2010
4,275 Posts
Well ive been busy (wedding in 2 weeks) But i got back at my BB 52 this weekend . I picked up a digital kitchen scale aswell so i could see just how over weight this little bird actually is . Started with a test flight about 3 weeks back during construction . Was windy and only partially assembled but had to try it . Part throttle and it flew around fairly well . The next Day i had to try it again, once again windy and this time i tried full throttle . Found out my KFM building needed some attention , Folded right in half and nosed in hard . Picked up all the pieces and glued them all together . I then decided to sheet it over with dollar store foam to make it look pretty again . Once the wing was repaired it had shrunk to 48" and lost a little dihedral . Now on what i consider its actual maiden it flew horrible . Acted like it was tail heavy and was very twitchy, wouldnt glide very well and i ended up having to cut the power and bring it in a little harder then i woulda like . Not alot of damage but i was very depressed after that flight . So this weekend i got it on the scale 41 oz flight read hmmm . Made a new spar and wing at 58" and got it out tonight . Had a little break in the weather and the wind was light . It flew great did 4 short flights and on the 4th landing the inner hub of 1 of my PZ corsair wheels broke so i had to pull the gear and try for a grass landing only problem was this thing just glided and glided . I tried to get it down on the lawn but just wouldnt go i tried to power up and clear the fence but the power lines above it had to much of my attention . Seems to have broken my plywood motor mount but other then that its A ok . what a nice flying bird dont need to use much power to fly this thing around . All grins

Chris
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Old May 03, 2010, 02:00 AM
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Kansas
Joined Dec 2005
183 Posts
I ran across this thread the other day and figure I would build one. Im using foam-board and made the plans fit the the build and material used, I did make some foam ribs for the wing to keep the airfoil consistent and added wing struts, re sized the horizontal stabilizer a bit to, running a turnigy 1700kv 9050ep prop, 10a hobby wing esc 9g tp servos and a berg 4l rx on a 2s pack not finished yet but here is a picture of whats done so far(and my messy build table lol) Ill post my progress with it, Thanks for the plans!!!
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Old May 03, 2010, 03:38 AM
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Joined Jan 2009
196 Posts
I have a question for all the successful 24" BB builders.

I started off building one out of 3mm depron and eventually got it to fly but the wing was too weak and snapped sending version one to its grave. Then came version 2, with ailerons on the under camber wing (no rudder). All painted very nicely in the scheme of a spotter plane used by the old SA Air Force called a "Bosbok", but the thing will not fly. I have to add it is built with 6mm depron, I added in some down and to the right thrust but when hand launched it simply banks to the left and spirals down, I do not want to scrap her so any help will be muck appreciated
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Old May 03, 2010, 06:44 AM
treefinder
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SE MI
Joined Oct 2004
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SA: Pictures will be helpful. generally my fb's and I have come to the conclusion that ailerons on the 24's aren't the best setup (particularly on the uc wing!). The best for us is UC wing and rudder/elevator, with that, we can do pretty much anything we want except extended inverted flight (dihedral insures that doesn't happen - can get inverted, but within a few feet, she's rolled back upright) With that small size, weight is pretty important (to minimize it, that is) so a lot will depend on what gear you used, how about a listing?
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Old May 03, 2010, 06:57 AM
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Thanks Springer

I will be doing some pics and listing tonight so that one can see where I went wrong. Do you think the 6mm depron is the problem. To convert to the rudder setup should not be a problem. I had to wait like forever for the perfect windless day to try it out and here you are saying when the wind comes up the 24 BB comes out to play!!!!!
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Old May 03, 2010, 07:51 AM
treefinder
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Well, yeah, but it's always best when the wind is still, then you can see where it "wants" to go as opposed to where the wind blows it compounded with where you are trying to go/correct, etc, etc.....

I have built the smaller guys in blucor (1/4") so similar to 6mm depron, and in a foam tray material that was thinner, maybe 4mm or so (but with a dense, stiff skin) and in Dollar store foam. All pretty much fly the same, so if weight is kept down (5-7oz) material shouldn't be much of an issue.

Just guessing here, but perhaps, you have a wing warp, or ailerons not balanced (or both). maybe very slight, but enough to just roll her over instead of flying straight. For me, ailerons have been definitely trickier to set up than RET. On the other hand, it's really fun to do those axial rolls once you get 'em right!!!
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Old May 03, 2010, 08:21 AM
AKA Don
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United States, MI, Houghton Lake
Joined Dec 2002
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Quote:
Originally Posted by SA/RCFlyer View Post
I have a question for all the successful 24" BB builders.

I started off building one out of 3mm depron and eventually got it to fly but the wing was too weak and snapped sending version one to its grave. Then came version 2, with ailerons on the under camber wing (no rudder). All painted very nicely in the scheme of a spotter plane used by the old SA Air Force called a "Bosbok", but the thing will not fly. I have to add it is built with 6mm depron, I added in some down and to the right thrust but when hand launched it simply banks to the left and spirals down, I do not want to scrap her so any help will be muck appreciated
If it rolls left with neutral stick then you need some right aileron trim.

Are you absolutely sure the ailerons are moving in the correct direction? I know I and other experienced flyers have ocasionally made that mistake. Left stick should raise the left aileron which will lower the left wing.


Don
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Old May 03, 2010, 11:01 AM
Registered User
Athens, Greece
Joined Apr 2009
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Quote:
Originally Posted by KDAylesworth View Post

Now if I can only find a way to get the servos and control horns lined up without cutting large "trial and error" holes on the fuselage, I'll have good solutions to all my most vexing construction issues.

Cheers!

Kevin
Kevin, I eye-ball the position of the servo outside the fuse and then I align an imaginary line from servo to control horn. Then I use a really sharp needle and poke a hole at the correct angle... Good luck!
Thanos
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Old May 03, 2010, 11:24 AM
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USA, TN, Fayetteville
Joined Dec 2004
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Dag Nabit, Too many post to read here... but you've all talked me into building a couple of these. I've got some friends that are wanting to learn to fly, and besides I just want to try one after reading the responses from folks on this thread. I've got some 1" thick EPP from some computer packing for the monoblock, and I went and bought some dollar tree foam for the rest of it. I've printed out the 33" plans, and taped them together.

The wife looks worried... They don't allow me to use sharp objects at work, because I seem to add blood sacrifices to all my projects when I do use them. When the Compaq vendor was handing out Swiss Army Knives, they made him give me a flashlight instead.

I used a box cutter to cut out the monoblocks for 2 planes last night... no blood yet!!! If I can find the time through the week, I'll get the rest of the parts cut out. I've ordered some 24g 1300kv motors and 5g servos... It's looking like a fun project... This will be my number 2 scratch build. I built a Parkflyer Pete last year, so I'm sure I can handle this...

Wish me luck... laugh... I really gotta make me one of those cnc foam cutters... but xacto blades sound a heck of a lot safer than a table saw...
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Old May 03, 2010, 11:33 AM
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Canada, BC, Williams Lake
Joined Jan 2010
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SA another simple question . how does it test glide when thrown with no power . you might need to either add more right angle to the engine or some aileron adjustment . The 33 i have mocked up will glide like nobody's business even into the wind but did roll right until i made a few adjustments .

Chris
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Old May 03, 2010, 11:37 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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The perfect cutter for building foamies are the small and large utility knives that have blades with snap off tips. The long blades will let you cut the thicker foam and also get that angled back when cutting to where it won't pull any snags. If you get the blade too vertical you can get a real ugly cut on the bottom.

On the 1" monobloc, you'll probably find a fuselage that narrow pretty hard to work in. If you bond two layers of it together it works better for getting stuff installed and it also gives the wing a wider cabin roof to rest on. I use the 2" blue board insulation for monoblocs and it is perfect.

Jack
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Old May 03, 2010, 12:41 PM
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USA, TN, Fayetteville
Joined Dec 2004
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Hmmm... I only have enough EPP to make 2 monoblocks... If I glue them together, I would have to find another... I've got some 1.25" EPP too...Maybe I will double it too... That would be a 2.5" monoblock... Would that be too thick?
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Old May 03, 2010, 02:24 PM
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Canada, BC, Williams Lake
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Mike get yourself a hot wire then your can cut foam and seal up and xacto knife injuries aswel

Chris
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Old May 03, 2010, 02:31 PM
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USA, TN, Fayetteville
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Hmmm hot objects....
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