Author Topic: Building the FJ-4-36 (Read 4302 times)

Bob Reeves · « **on:** January 04, 2012, 07:44:47 AM »

Building the first FJ-4-36 from Eric's laser cut parts. Discovered a few errors in my CAD drawings but all will be corrected before Eric creates the final version of the laser parts. This is why we build prototypes, to catch the things that are hard to translate from 3 dimensions to a 2 dimension drawing. Having swept wings really makes it interesting..

First photo is removing the parts from the sheets, I really love laser cut parts.

2nd photo is the start of the wings, it builds identical to the FJ-4-15 just bigger. The wings are built in halves then joined together in the center. Makes it easier to cut and trim the sheeting.

3rd photo shows all the top sheeting applied. This is done while the wing is still held down to a flat building surface to hopfully keep it straight. The ribs are cut with built in tabs to set the dihedral and keep everything straight.

Bob Reeves · « **Reply #1 on:** January 04, 2012, 08:00:01 AM »

Had to build up the rudder in order to know where to grind out what will become the hole in the fuselage for the carbon reinforcement tube.

1/4 Fuselage sides are almost ready to be joined. The brass tube for the cross-over throttle linkage is installed using epoxy in a slot cut with a Dremel using a 1/8 round burr.

And just for prospective this is how it compairs in size to a MO-1. The bottom leading edge sheeting is drying on both wing halves.

Douglas Ames · « **Reply #2 on:** January 04, 2012, 01:57:49 PM »

Really cool stuff Bob.
What are you going to use to join the fuse. sides? Epoxy, resin or Gorilla glue? Any laminates in between?

Douglas Ames · « **Reply #3 on:** January 04, 2012, 02:02:14 PM »

Have you picked out a color scheme yet? Some inspiration...

Bob Reeves · « **Reply #4 on:** January 04, 2012, 02:15:24 PM »

Nothing between, used a combination of tightbond and gap filling CA. I put tightbond around all outside edges then used gap filling (slow) CA on the interior. The tighbond will cure on the outside edges and it's easier to sand, the CA acts like a clamp when you press the two sides together. Use the same trick when gluing the leading edge sheeting to the leading edge spar. Run a bead of tightbond between the ribs then put a drop of slow CA at each rib. Line up the sheeting and press it into place. I do use a pin between the ribs to make sure the tightbond is clamped well.

As far as paint, you know me it will be just like the others in my old squadron dress.

Bob Reeves · « **Reply #5 on:** January 11, 2012, 03:01:31 PM »

Haven't been able to do allot of work on the FJ, have a money making project I'm in the middle of that is taking most of my time. Did manage to get the main gear mount built and installed in the wing. Also built the tip weight box into the outboard wing tip, was pretty happy all the parts fit just like they were suppose to.

Items left to finish the wing are bottom center and tip sheeting, cap strips and wing tips. Thinking I'll wait till I figure out how I'm going to do a slider before I sheet the bottom of the wing. Will probably run the release in the wing but torn between a carbon tube slider and trying to adapt Bill B's wire slider. Going to take some experimentation either way...

Douglas Ames · « **Reply #6 on:** January 11, 2012, 10:52:12 PM »

The weight box looks trick. Lot's of room.

Bob Reeves · « **Reply #7 on:** February 05, 2012, 03:52:18 AM »

The work project is at a temporary lull so headed to the shop to get back on the FJ. Decided to go with a Carbon Tube slider, ordered a couple Sullivan 507 Cable Gold-N-Rods from Brodak, should be here sometime next week. I have a small mill so cutting the slot in the CF tube shouldn't be much of a challenge, thanks to Bill and Dale for pointing me in the right direction. Will post pictures...

Also been working with Eric at RSM finalizing the laser parts and plans he is going to make available.When I get the slider worked out and added to the plans it should be ready for prime time..

Wayne J. Buran · « **Reply #8 on:** February 05, 2012, 04:36:12 AM »

Looks nice Bob. Thanks for the update.
Wayne

Bob Reeves · « **Reply #9 on:** February 05, 2012, 06:48:44 AM »

This is what I managed to get accomplished this morning.. Almost need to wait till I receive the Gold-N-Rod release cable before I can go very much further. First I found a piece of scrap spruce and milled a slot across both with a round nose end mill. These will become the holding jig to cut the slot in the carbon tube. Glued the carbon tube into the slots with thick CA and clamped the whole mess to my mill. Cutting the slot was a piece of cake.

Last photo, is a close up of the slot with a section of 1/8 brass tubing inserted in the carbon tube..

Bob Reeves · « **Reply #10 on:** February 05, 2012, 07:09:55 AM »

Next I needed to figure out how I was going to mount it in the wing. Started with a rat tail file I bought a long time ago for sharpening a chain saw. This is the best file I have ever seen for gnawing out round sections of balsa. Started cutting a slot in the top of the wing with the file then finished it up using a slightly smaller carbon tube wrapped with sticky sandpaper. This made the slot fit the carbon slider just perfect. I'll add another partial rib on the inside of the carbon tube to give it more glue area and cap strip it to give the wing covering something to hold on to.

Have the forward and rear line position worked out from the CG and trailing edge. Will cut the tube long enough to allow the carrier to reach these points when I get the release figured out. Wished I have thought about this and ordered the release cable while I was off doing other stuff. Can probably make the line carrier and just trim it to size when I get the cable and see where it's going to end up.

john vlna · « **Reply #11 on:** February 05, 2012, 05:37:39 PM »

Bob
An impressive build. I can't see how far back your slider goes but remember you can only go to the rear of the wing cord at the fuselage. Since you have a swept wing this will be well in front of the TE at the tip.
John

Bob Reeves · « **Reply #12 on:** February 06, 2012, 07:00:30 AM »

Thanks John, yes I know about the slider rule and have the rear position marked on the plans. One drawback to having a swept wing, but it won't be too bad. Even with the wing sweep the leadouts can go about 4 1/2 inches behind the CG which is only about 1/2 inch less than the plans I have for an MO1 show. Doubt 1/2 inch will make much difference and I believe a swept wing adds to the low speed stability (Subject for another thread please).

Didn't get allot done this morning as I am waiting on the epoxy I glued the plywood sided for the brass line carrier to cure. I know I've seen oval eyelets which would make the line carrier allot easier to make but who needs 100 of the darn things for two or three airplanes. I'm pretty much copying Bill's setup off the MO-1 he built. After the plywood/brass sandwich cures I'll stick it in my mill and cut a nice slot for the lines to pass through.

When thinking of how to cut the slot in the brass tube part for the line carrier I thought about the setup I used to cut the slot in the carbon tube. 1/8 brass tubing fits well in the arrow shaft I'm using so I cut another piece off and glued it to the spruce pieces I used to slot the CF tube. Now I have a jig for slotting 1/8 brass tubing on the center line. First photo is the setup in the mill, 2nd is the result showing it stuck in the end of the CF line slider.

Bob Reeves · « **Reply #13 on:** February 06, 2012, 07:08:33 AM »

While waiting on epoxy to cure I did get another rib cut (need to add it to the laser cut file) to place on the inside of the carbon tube slider. Installed the cap strip and did a test fit of the slider tube. The tube is flush with the top of the wing at the high point and I feel once it's glued into the resulting slot it should be plenty strong enough. Camera angle makes the cap strip look like it's crocked but it really isn't.

Bob Reeves · « **Reply #14 on:** April 03, 2012, 06:52:17 AM »

Well it's been a while but managed to get back on the FJ long enough to get the slider release cable installed. This should have been done before sheeting the bottom leading edge but I made due by cutting a hole in the sheeting. The photos kinda tell the whole story. The real difficult part resulted from the need to have the release wire at an angle and getting the holes drilled in the carbon tube and slider at the proper location and angle. It would have been easy if I could have gone straight in to the side of the tube at a 90 but then I would have had much more of the release wire above the wing.

john e. holliday · « **Reply #15 on:** April 03, 2012, 07:26:21 PM »

Looking good.

Bob Reeves · « **Reply #16 on:** April 11, 2012, 09:17:37 AM »

It's almost ready to start the finish. Wing is complete and glued into fuselage, fillets are done, stab is glued on. Fillets need to be done before installing the bellcrank platform, else you will be trying to work between it and the wing. Thinking I'll just use Monokote on the wings and paint the fuselage with Lusterkote. As much as I hate Lusterkote it will make for a quick finish.

Bill Little · « **Reply #17 on:** April 12, 2012, 03:06:49 PM »

Looking good, Bob! I have missed what you are going to use for power. ??

Thanks!
Bill

Bob Reeves · « **Reply #18 on:** April 12, 2012, 03:29:23 PM »

Quote from: Bill Little on April 12, 2012, 03:06:49 PM

Looking good, Bob! I have missed what you are going to use for power. ??

Thanks!
Bill

Thunder Tiger 36 with a Perry 2600 carb. This is the least expensive easiest to get combination for a profile. Won't keep up with a Nelson but is pretty good and runs reliably.

eric david conley · « **Reply #19 on:** April 12, 2012, 05:46:53 PM »

And if you want it to go a little fast you can use the Perry 1301. Eric

Bob Reeves · « **Reply #20 on:** April 13, 2012, 09:02:35 AM »

Quote from: eric david conley on April 12, 2012, 05:46:53 PM

And if you want it to go a little fast you can use the Perry 1301. Eric

Haven't tried the 1301 so not sure about this... My guess is you would end up in the same boat as with the stock TT carb, needing to run pressure to get it running reliably.

Quote from the Profile Carrier rules...

"No pressure fuel systems will be permitted; however, the vents in the tank may be pointed forward in the air stream."

john vlna · « **Reply #21 on:** April 13, 2012, 10:40:46 AM »

Bob,
I use the OS 4d on my tiger 36. Don't know how it compares to the perry's but it works very well. I have it on a piped motor and is it several seconds faster than any other TT 36 I have seen. Low speed is also good, although the pipe can cause it to want to accelerate too much, but that is not the carbs fault.
John

eric david conley · « **Reply #22 on:** April 13, 2012, 11:02:28 AM »

I have used the 1301 numerous times in my TT-36s, in fact its the only carb that I use in that engine and have had no trouble with draw in any of them (no pressure). For some reason the stock TT carbs wont run right unless they are on pressure. The OS 4D is a great carb and seems to work well on almost any 32+ engines I just got use to the Perry's so use them. Eric

john vlna · « **Reply #23 on:** April 13, 2012, 07:51:31 PM »

Eric,
The problem with the stock TT36 carb is the way the fuel comes in. There is sort of retaining ring which won't draw right with out pressure. It doesn't take much, muffler pressure is enough.
John

Bob Reeves · « **Reply #24 on:** May 08, 2012, 10:50:42 AM »

Slowley getting there...

If you are wondering why the elevators are white it's because I got sick of trying to cover them with that crappy Coverite and just went with some Monokote I had left over from another project.

http://stunthanger.com/smf/index.php?topic=26515.0

Bob Reeves · « **Reply #25 on:** May 11, 2012, 02:32:57 AM »

In the process of building the hardware and getting all the mechanics working. Really liked Bill's blind nut method of attaching lines to the bellcrank but knew it would be a chore for me to accurately make a hex head out of a blind nut. Looking through my junk hardware drawer, found a few threaded standoffs that were made of steel. They are metric but thought it would be much easier for me to start with hex stock and this is the result.

The standoffs are about 1/2 inch long, started by turning a shoulder that would fit the line eyelet on each end then used a cutoff tool to separate the piece into two parts. The black screw is a 4-40, the other is metric and what will probably be installed in the bellcrank.

Darrel · « **Reply #26 on:** May 11, 2012, 08:36:28 AM »

Really like your plane and workmanship. Looking good.

Darrel

Bill Little · « **Reply #27 on:** May 11, 2012, 05:15:50 PM »

Quote from: Bob Reeves on May 08, 2012, 10:50:42 AM

Slowley getting there...

If you are wondering why the elevators are white it's because I got sick of trying to cover them with that crappy Coverite and just went with some Monokote I had left over from another project.

http://stunthanger.com/smf/index.php?topic=26515.0

Hi Bob,

I think it really looks nice! Anyway, control surfaces are often white on NAVY jets.

BIG Bear
RNMM/AMM

catdaddy · « **Reply #28 on:** May 25, 2012, 10:10:58 AM »

Hey Bob, shouldn't the last three numbers on that tail number be 422

Looks great, you guys have fun at Brodaks! I may come out to the field sometime Sunday just to visit.

Brad Smith · « **Reply #29 on:** May 26, 2012, 11:02:32 AM »

Hey Catdaddy good to see you are still around how you been drop me an email sometime dude.

Darrel · « **Reply #30 on:** August 22, 2012, 10:02:36 AM »

Bob, very interesterd in your project. What's the latest and wasn't this going to be a kit also?(I hope so)
Let us know how it flys if you have flown it.

Darrel

john e. holliday · « **Reply #31 on:** August 23, 2012, 09:38:42 AM »

Watched the planes fly in Tulsa and they both flew great in Joe Gilbert's hands.

Bob Reeves · « **Reply #32 on:** August 24, 2012, 10:16:05 AM »

Quote from: Darrel on August 22, 2012, 10:02:36 AM

Bob, very interesterd in your project. What's the latest and wasn't this going to be a kit also?(I hope so)
Let us know how it flys if you have flown it.

Darrel

Sorry didn't see this sooner, been tied up with other stuff...

I was trying to work with RSM on a laser cut short kit but communications seem to have gone by the way side after I sent him the last cad files. I may just put it in public domain and upload the plans and laser file to my web site. Give me a few days to get the present project out of my way and I'll do something...