Author Topic: How do you mount belcrank in a foam wing core. (Read 7088 times)

ringmaster · « **on:** January 22, 2015, 04:45:00 PM »

Hello, does anyone have any photos how to mount a belcrank in foam wing core.

Randy Cuberly · « **Reply #1 on:** January 22, 2015, 05:09:21 PM »

I think Bob Hunt has a whole booklet on how to do it...Mayabe he'll chime in!

I have photos of just about anything else but can't seem to find any on that!

Randy Cuberly

Leester · « **Reply #2 on:** January 22, 2015, 06:01:46 PM »

Go to the Electric Forum and look at The Legacy 40 build by Crist Regotti, at the bottom of the first page you'll see his B/C assembly. Send him a Personnel Message he might have pics of the install. If not he can explain it. I know how just describing it..

Crist Rigotti · « **Reply #3 on:** January 22, 2015, 06:22:57 PM »

Yup, contact me if you need to. I have lots of pictures and know how on foam wings.

mike londke · « **Reply #4 on:** January 22, 2015, 06:34:40 PM »

Solid or hollow core? Internal or external bell crank?

Crist Rigotti · « **Reply #5 on:** January 22, 2015, 09:37:26 PM »

Ringmaster,
Watch your email.

Brent Williams · « **Reply #6 on:** January 22, 2015, 11:08:51 PM »

I would also be interested in learning about some of the ways to install the bellcrank assembly inside of the foam wing panel.

I have built a few foam wing planes with external leadouts and the bellcrank mounted on a pinned tab. I haven't ventured any further down the building skill path and installed the bellcrank/leadouts inside the wing panel yet. I'm very interested in learning from all you seasoned experts about what methods have been successful and which methods were unsuccessful in your foam wing designs.

Bob Hunt · « **Reply #7 on:** January 23, 2015, 04:56:35 AM »

Hi all:

This is a very simple process, and the photos attached should tell the story.

I file a 1/8-inch wide slot just behind the vertical lite-ply spar. This slot is usually 5/8 to 3/4 inch deep. This allows the bellcrank on its port to be positioned in such a manner that the pushrod is close to the centerline of the wing as it exits the wing. On profile models where you want the pushrod off center, this slot is not required. The rod on which the bellcrank is assembed is pushed into the slot and positioned vertically as required, and is then held in place temporarily with a dab of 5-minute epoxy applied top and bottom where the bellcrank post rests in the slot. The actual bellcrank mounts that will provide the strength required for flight and pull test loads will be installed after the wing has been installed in the fuselage. At that point two plywood plates - one on top and one on the bottom - are fitted between the fuselage sides and over the bellcrank post.

Once the bellcrank is installed the wing panels can be joined. Be sure to do a "dry" test fit and while doing that insure that full and free bellcrank swing is available and that the pushrod has ample clearance to move throughout its travel without touching any foam or the vertical plywood spars.

Later - Bob Hunt

ringmaster · « **Reply #8 on:** January 23, 2015, 05:10:59 AM »

Thank you very much for your nice photos of the belcrank in foam wing makes things a lot clearer Bob Hunt you are very kind , Bob how much for a set of foam wings for a Sig Twister and Sig Banshee cost plus shipping and do you take US money orders for payment, I live in Canada Thanks

Jim Carter · « **Reply #9 on:** January 23, 2015, 10:40:41 AM »

Hi! I know I may be a bit late but this is how I've done it on a number of my foam wings and haven't had a failure yet that can be attributed to a failure of the bellcrank ot the mount .... lousey piloting ..... well that's a whole 'nutha' story! All of my foam wings have just been from the inexpensive beaded foam that I sheet over usually with an application of Sig Bond glue. Basically, I epoxy the two halves together, cutout the center section so the plywood bellcrank mounting plate will sit just below the top surface of the wing, cutout the channel and epoxy in place the plastic housing for the .018 leadout wires, apply the wing sheeting, make the cutout for then install the elevator pushrod and "bingo" that's how I do it!! Hope it helps.

ringmaster · « **Reply #10 on:** January 23, 2015, 10:59:59 AM »

Thank you my friend showing your Sig Banshee foam wing belcrank mounting with sigment glue.

Derek Moran · « **Reply #11 on:** January 23, 2015, 02:13:40 PM »

You're almost as funny as Howard!
Derek

john e. holliday · « **Reply #12 on:** January 24, 2015, 08:39:40 AM »

Do as Bobby H says and you will have no problems. I still remember my first kit of the SIG Mustang Stunter. I did the bell crank mount like the instructions. Can't remember how many flights I had on it when all of a sudden controls were locked and no more Mustang. The second one has ply plates top and bottom in the foam core. Now I do it like Bobby and the other pros.

Motorman · « **Reply #13 on:** January 24, 2015, 04:44:26 PM »

Any pics of the profile installation.

Brent Williams · « **Reply #14 on:** January 24, 2015, 11:39:12 PM »

Hey Bob,

Could you elaborate on the bellcrank mount method used on this neat profile plane, the "Joe Nall Cadet"?

Actually, could you elaborate on that plane a bit also?

ringmaster · « **Reply #15 on:** January 25, 2015, 07:56:03 AM »

That is sure a nice looking plane Joe Nalls Cadet. Where you get the plans for that nice plane and who cut the foam wings for it for electrics, sure looks neat I think, I sure love it. Thanks for letting me look at it.

john e. holliday · « **Reply #16 on:** January 25, 2015, 02:23:31 PM »

I would contact Bobby Hunt his self.

Chris Wilson · « **Reply #17 on:** January 25, 2015, 08:16:52 PM »

So in essence the bell crank is mounted to the fuselage and it just so happens that the wing gets in the way - foam or not.

Bob Hunt · « **Reply #18 on:** January 26, 2015, 06:38:55 AM »

Well put, Chris!

To help answer the questions from Brent and "Ringmaster" about the Joe Nall Cadet, I'm posting a few photos. The "Cadet" features a non-cored foam wing that I cut. The inboard core has a slot to allow free swing of the leadouts for adjustment. There is a center rib that is made from a piece of 1/2-inch thick, medium weight balsa. The bellcrank mounts to a plywood tab that is in the shape of a "T". The top legs of the "T" fit against the outboard side of the hard balsa center rib, and the stem goes through a slot in the rib, yielding a platform on the inboard side of the rib to which the bellcrank mounts. I put small plywood pieces where the top legs of the "T" brace up against the balsa rib to prevent crushing from line pull. Once the bellcrank/pushord assembly is mounted, the two wing halves are assembled to the center rib in the cradles from which they were cut. Easy peasy... Of course clearance for the pushrod is cut from the inboard wing panel before assembly.

The Cadet wing is cut with channels top and bottom to accept 1/2 inch by 1/8 inch basswood spars. In several places under the basswood strips along the span of the wing, there are 2-inch long, vertical grain, hard balsa shear webs installed that connect the basswood strips on both sides of the wing. The shear webs prevent the spars from "racking" (moving in opposition to each other under maneuvering loads). The leading edge of the wing was then covered with .2 ounce carbon mat, attached with water-thinned Titebond wood glue. The mat on the leading edge goes from the back of the basswood spar on the top, around the leading edge, and ends at the back of the back of the basswood spar on the bottom. I also coveerd the center section of the wing with the .2 ounce carbon, as well as applying a strip to the top and bottom of the with at the trailing edge. That strip was about 1 1/2 inches wide, and it served to stiffen the TE against damage. You just can't imagine how strong the carbon mat makes the wing!

I've received a number of requests to kit or make the Joe Nall Cadet available in plan form. I have decided to redesign the model somewhat to allow for movable flaps to be installed, making this a more useable model for stunt training.

The attached photos should explain a lot about the model and the construction technique. I must credit Phil Cartier for much of the wing construction methodology. The carbon idea was mine...

Later - Bob Hunt

Allan Perret · « **Reply #19 on:** January 26, 2015, 10:26:45 AM »

Lots of nice construction features which makes this a fast and easy build for beginners..
Couple of questions
What material is fuse nose section, or is it a lamination ?
The solid wire leadout terminations at the bellcrank, was the twist done with any special tooling or just holding the loop with pliers and wrapping by hand. What size wire you using there ?

Will Davis · « **Reply #20 on:** January 26, 2015, 05:35:28 PM »

As his post shows , Bob has another great way to mount a bellcrank in the foam wing,

I flew one of Bob's Joe Nall Cadet models at Joe Nall, although designed as a trainer, the model performs well doing the full ama pattern, it is a great transition model to help anyone to progress to intermediate class and in the right hands can be very competitive in most profile events .

Good solid design, innovative building materials, lightweight , simple , all makes this a very impressive model ,

Bob Hunt · « **Reply #21 on:** January 26, 2015, 06:53:23 PM »

Quote from: Allan Perret on January 26, 2015, 10:26:45 AM

Lots of nice construction features which makes this a fast and easy build for beginners..
Couple of questions
What material is fuse nose section, or is it a lamination ?
The solid wire leadout terminations at the bellcrank, was the twist done with any special tooling or just holding the loop with pliers and wrapping by hand. What size wire you using there ?

Hi Allan:

Thanks for the kudos on the construction features; it does indeed make for a quick and relatively inexpensive project for beginners and intermediate level fliers. However, this same construction methodology was used in making the test bed twin that Buddy Wieder and I built. It is perfect for "fast testbedding." (See the attached photos of the testbed twin.)

The fuselage nose section was made from a core piece of 1/2-inch thick balsa. Then 1/32-inch thick plywood doublers were attached to each side of the core piece to yield a 9/16-inch thick nose section. The nose section was designed to accept the wing, the landing gear mount, the motor mount and the
battery mount. Hard points were put into the balsa core piece before the plywood doublers were glued onto it. This nose assembly was then grafted to a rear fuselage section that was made up from a foam core and balsa sides. The thickness of this part was engineered to match the thickness of the nose piece, plus a few thousandths of an inch to allow the balsa to be sanded into the doublers for a perfect thickness match. The accompanying photos should help here to explain the process.

Later - Bob

ringmaster · « **Reply #22 on:** January 28, 2015, 10:25:17 AM »

Hello Bob, That is cool looking twin electric powered plane. I bet she will really move fast. That is real sweet I like that Thanks for showing me that.

Bob Hunt · « **Reply #23 on:** January 28, 2015, 11:04:44 AM »

Thanks, Ringmaster for the nice words about the testbed twin. Actually it was designed to do the pattern at a slower than normal pace. The two props provide lots of low-gear torque, but also provide lots of downhill brakes as well. I have 20 total inches of disk span on this ship.

Later - Bob

Tim Wescott · « **Reply #24 on:** January 28, 2015, 03:39:22 PM »

Quote from: Bob Hunt on January 28, 2015, 11:04:44 AM

I have 20 total inches of disk span on this ship.

I know this belongs in the engineering forum, but -- I suspect it's disk area that matters, in which case you have around 157 square inches of total disk area, which is pretty close to the disk area of a single 14 inch diameter prop.

Bob Hunt · « **Reply #25 on:** January 28, 2015, 05:22:44 PM »

Hi Tim:

I disagree with you about the benefit coming from the disk area. The "artificial" air blast from the 20 inches of disk span makes the wing, flaps and elevator more "lively." No one will ever convince me otherwise...

Bob

Tim Wescott · « **Reply #26 on:** January 28, 2015, 06:25:25 PM »

Hmm. I was latching onto your "airbrakes" comment, which I think is going to go with disk area.

But yes, having a wider swath of air blowing over the flaps and elevators should make a difference. And you can probably lay a valid claim to being more of a pilot than me, and certainly have infinitely more experience than I do with CL twins.

Hmm again.

Randy Cuberly · « **Reply #27 on:** January 29, 2015, 06:53:53 PM »

Quote from: Tim Wescott on January 28, 2015, 06:25:25 PM

Hmm. I was latching onto your "airbrakes" comment, which I think is going to go with disk area.

But yes, having a wider swath of air blowing over the flaps and elevators should make a difference. And you can probably lay a valid claim to being more of a pilot than me, and certainly have infinitely more experience than I do with CL twins.

Hmm again.

UUUhhhhhhh...Yeah Tim, Bob is a better pilot than about 98% of us and about as good as the other 2%.

Randy Cuberly

Allen Eshleman · « **Reply #28 on:** December 07, 2020, 05:51:53 AM »

Thanks so much for these diagrams. I have found them to be very helpful.

phil c · « **Reply #29 on:** December 08, 2020, 08:29:13 PM »

I'll dig through my pictures but until I find one:

The simplest way is to use a half inch hard balsa center rib. Mount the bellcrank on a 1.25in. strip of 5ply hard plywood. The bellcrank should be half an inch from the end. Make the strip over long, about 3in. long for trimming.
Locate the mount so the bellcrank bolt is behind the spar and install it so the bellcrank is more or less centered between the spars and the bellcrank is aimed for the push rod(s) to hit the flap horn(if used) and the elevator horn.

Lead out holes, if the wing is not hollow, can be done with a 1/8in. drop wire jig. Make a couple of guides, mount then on a 4-5ft piece of ply wood near one end and screw it to a wall. Make sure the two guide tubes line up vertically from the board and let the 1/8 wire drop freely, and parallel to the board. Mark the location the wire will follow with a line to the end of the board.

Make another jig assembly to hold the wing panel in place. That usually is a piece of foam left over from the sheet the panel is cut from. It may need some foam backing and a piece of plywood to stiffen it.

Cut the leadout holes from the tip to the root. Take some care, and do some tests to make sure you can line everything up properly and the wire will drop smoothly. Heat the end of the rod red hot. Drop it into a scrap strip of foam and see how it tracks. It will probably take 2-3 reheatings of the drop wire to make it through a 24-30in. panel.

The leadout hole maker can be made as sophisticated as you want. I was able to melt leadouts into 24in. panels just by marking the path lightly on the panel, heat the end of the wire, and doing the melting by eyeball. Just take care not to burn yourself.

Or you can a go hole hog with a motor driven table-slide for the foam, an electrically heated tip, and even a stepper driver run by a Raspberyy Pi or other mini-micro processor.