It be flying weather here, so the building has had very little attention.

I seem to be fixing the other planes that I might have had a little opps with at the field.

I did blend the hinge line in with the upper and lower ribs.
I used the razor plane to take the excess balsa off being careful not to nic any of the ribs. Finished up with the sanding bar.

Chris

Added the bevels to the front of the elevators and a mounting block to the right elevator for the control horn

Tapered and rounded up the stab leading edge, blending it to the ribs.

Chris

With the bevels added to the elevators, I can now cut the slots for the hinges and trial fit them.

I used the standard Dubro nylon pinned hinges.
It is pretty straight forward as you can see the supports I added for the hinges to give them a little more surface area for gluing.

Just to mention, I had to install the hinges at an angle on the stab side.
The reason is the drive wire from the bellcrank to the rudders is sharing the same area. The slot for the hinge still starts in the middle of the stab trailing hinge line but it angles down into the support piece. The hinges still work the same but now they won't interfere with the rudder drive wires.

After fitting it altogether I noticed the joiner wire was a little out because one of the elevators was higher that the other one. Could be the holes I drilled into the elevators are not quite at the same angle. A little bending on the wire and both elevators were sitting flat on the build table.

Chris

Looks nice Chris, more neat and tidy carpentry as usual. I'm very interested to see how your rudders work out as there are one or two twin fin designs I really fancy, and why spend ages working out a solution when you can steal someone elses!

Originally Posted by Sundancer

Looks nice Chris, more neat and tidy carpentry as usual. I'm very interested to see how your rudders work out as there are one or two twin fin designs I really fancy, and why spend ages working out a solution when you can steal someone elses!

Ha Ha. No one is stealing here. We are all sharing ideas hoping that we can make these old designs fly with at least a little control over them.
If you need to borrow a solution, go right ahead. Personally I am constantly looking myself for that golden idea that I can borrow for a future build.

Chris

I have decided to put the horizontal stab aside for now and concentrate on those twin outboard vertical stabs. There are still a few details to complete with the horizontal stab but they will have to wait as I need to work on the twin stabs first.

The plans call for the vertical stabs to be made out of 3/16" sheet balsa.
Two 3" pieces butt glued together to make the required 6" piece.
Well, that is the easiest method but I would be contending with the sheet balsa warping in the future.

Another solution is needed.

I thought about laminating up 3 x 1/16" sheet balsa to the required size and staggering the joints. It would be strong and warp free but heavy.

Need another idea.

I could build up the outline with straight 3/16" balsa and then cut the curve into it like the trailing edge of the wing I build earlier.
No. It would work but kind of clunky.

I remembered reading an article on laminating just the outer edges and building up the inner parts. Light and structurally strong. I like it! This is a building technique I have never done before and I would like to try it out.
If you have ever built a Lazy Bee you know what I am describing.

The pic shows the original built-up vertical stab outline from the plans.
The new outline with 3/16" removed from the outer perimeter and finally the foam mold I will be using to form the outer laminations.

Chris

Good choice Chris! I am a great fan of laminating to produce items with curved outlines, it is definitely the superior way to do this giving good strength and light weight. If it is of any help, I went into a fair amount of detail on this on my build log for the Tom Tit 2x - http://www.rcgroups.com/forums/showthread.php?t=1485005 To get around the quite severe curves of your fins you will need to soak or steam the strips pretty well, plain water works OK for me but if you use a solution of household ammonia (hold your breath!) the strips become very flexible in deed. One final thing; if you want to propduce really strong laminations, as your fins are going to support the back end of the model this might be worthwhile, you can include one lamination of 1/32" or 1 mm ply as an extra strip in the centre.

Originally Posted by Sundancer

Good choice Chris! I am a great fan of laminating to produce items with curved outlines, it is definitely the superior way to do this giving good strength and light weight. If it is of any help, I went into a fair amount of detail on this on my build log for the Tom Tit 2x - http://www.rcgroups.com/forums/showthread.php?t=1485005 To get around the quite severe curves of your fins you will need to soak or steam the strips pretty well, plain water works OK for me but if you use a solution of household ammonia (hold your breath!) the strips become very flexible in deed. One final thing; if you want to propduce really strong laminations, as your fins are going to support the back end of the model this might be worthwhile, you can include one lamination of 1/32" or 1 mm ply as an extra strip in the centre.

Thankyou for the link. Picked up some very useful build techniques that I will use in the future. Now I have to go over your other past build threads to hopefully glean any other great ideas.

Looking at your lamination technique. Do you put wax on the ply strip you use to keep the pins from putting dents in the balsa strips? Maybe something else to keep it from being glued to the lamination.

I have finished the laminations so I can't use the 1/32 ply in the vert. stab. but I think they will work just great the way they turned out with just the balsa. Much stronger than what I originally thought they would be. I will post the process I used tomorrow.

Chris

Glad the laminations have come out OK Chris. No, I don't normally wax the ply protective strip, but it would be a good idea to do this to take care of any stray glue that might squeeze out.

I should warn you that laminating outlines is one of those techniques that can become addictive, there is just something so satisfying about the finished product! You will find yourself looking a wing and tail tips made from glued together sections of flat sheet with a frown and thinking they would be so much lighter and stronger if laminated.

It's funny how many people shy away from using laminated tips, they are actually easier,quicker and stronger than sheet tips and I can never get the angles to fit properly on the segmented type.

Laminating turned out to be very easy and I am very happy with the results.
I cut the foam form at the hinge line. This allowed me to use smaller lengths for the strips.
Since this was kind of a trial run I decided to laminate in stages.

I stripped six lengths of 1/16" soft balsa. Three for each half of the form.
I found soaking the strips under hot water straight out of the tap was enough to allow them to bend around the forms. They were attached to the forms with elastics until dry. I didn't use glue at this stage.

When they were dry in the morning, I removed the elastics and separated the laminations as you can see in the first picture. I next glued them up with Weldbond and reattached them to the forms with the elastics till dry as seen in the second picture.

The one disadvantage was the elastics added impressions to the balsa.
I was able to steam the dents out with a wet paper towel and hot covering iron. I like George's solution he presented earlier with the protective strip and pins. Elastics will not work with some odd ball forms. I might try the protective strip and elastics in the future. I was happy I could steam the dents out of the balsa with the method I used.

The last picture shows the second vertical stab. drying while I have the first one pinned to the plan. The hinge line balsa has been added and I will begin to fill the inside with the support structure.

Chris

Originally Posted by Tomahawk

The one disadvantage was the elastics added impressions to the balsa.
I was able to steam the dents out with a wet paper towel and hot covering iron. I like George's solution he presented earlier with the protective strip and pins. Elastics will not work with some odd ball forms. I might try the protective strip and elastics in the future. I was happy I could steam the dents out of the balsa with the method I used..

Chris

Per a "laminating tutorial" by Pat Tritle, I used tape to hold the laminations to the form. I taped down the pieces to one end of the form and then 'pulled' them around the form, one at a time with titebond adhesive holding the outer layers in place. The tension from pulling on the wood as I curved it around the form seemed to help prevent breakage that I experienced earlier when trying just to push the pieces up against the form. After each layer was pulled around the form, I taped the opposite end down. This gave me a staggered series of tape joints at each end, so I had to make sure the forms provided extra length at each end to provide room for the end tapes. I also added tape spaced between the ends if needed after I put on my last layer. My 'soaking tube' is a length of 3/4" PVC with a cap glued to one end and one friction fit on the other.

I also tried using a 12 to 15 second microwave of the laminated parts, which seemed to work quite well, per another 'tutorial' recommendation.

Your work looks great! Waiting with "bated breath" for further progress.

Pete G.

Originally Posted by P_J_Glor

Per a "laminating tutorial" by Pat Tritle, I used tape to hold the laminations to the form. I taped down the pieces to one end of the form and then 'pulled' them around the form, one at a time with titebond adhesive holding the outer layers in place. The tension from pulling on the wood as I curved it around the form seemed to help prevent breakage that I experienced earlier when trying just to push the pieces up against the form. After each layer was pulled around the form, I taped the opposite end down. This gave me a staggered series of tape joints at each end, so I had to make sure the forms provided extra length at each end to provide room for the end tapes. I also added tape spaced between the ends if needed after I put on my last layer. My 'soaking tube' is a length of 3/4" PVC with a cap glued to one end and one friction fit on the other.

I also tried using a 12 to 15 second microwave of the laminated parts, which seemed to work quite well, per another 'tutorial' recommendation.

Your work looks great! Waiting with "bated breath" for further progress.

Pete G.

Hey Pete. Always nice to hear the comments and build tips.

I was wondering if you could elaborate a little more on the Trittle tips.
Did the balsa go on wet with water or just the Titebond glue?
What type of tape did he use?
Was the microwave used for drying?

Thanks
Chris

It looks like it is going to take awhile to fill in all the triangles and stick bits.
Working on just the one fin tonight and I will be still working on it tomorrow.

Here is a builder tip. You pro builders out there already know this but there are always new builders still gaining experience.

The pic shows the proper way to cut out triangles for added strength.
The triangle is cut for a simple 90 degree support.
You cut your first 45 degree angle off the stick. This endcut is useless and you can throw it in the burn bucket. Don't use it!
Flip the stick over and cut the second 45 degree. This is the piece you want. It is very strong in compression as the grain of the wood is straight from one side to the other. If you look at the endcut piece it isn't and not suitable for building.

Chris

Wow, we have had fabulous flying weather this week and building sure has taken a back seat to flying.
Trying to even glue a stick into place has been an effort.

I have one vertical stab. filled in with all the triangles and support sticks.
I have yet to sand it down and it looks rough in the picture.
Now I have to work on it's twin.

Chris