Thunderbird

[Dwayne]

I just acquired this beautiful Thunderbird the gentleman that gave it to me has no idea when he started it that's how old it is, definitely 70's or earlier, as it is with a Enya 29 it weighs 37 oz.  The leadouts are very far apart and the throws are very short, that is it takes very little pull on the leadouts to go from full up to full down. I think the 29 is to small and I should change the lead out spacing, I don't know alot about this plane MkI or II? wing area? But he did some nice work. 

[EddyR]

Nice to see one built with the speed style cowl like Bob Palmer's original. The .29 should be mare than adequate if you use 59-60 ft lines.  Moving the lines closer together will not slow down the controles any. I would leave them where they are. The Veco kits used solid ribs. There is no room for the leadouts to move.
Ed

[Tim Wescott]

Yup, your choices are to leave it as-is like EddieR suggests, or commit to uncovering the entire left bottom wing from tip to center sheeting so you can replace the entire control system and make new holes in the ribs to boot.

You could try just uncovering the bellcrank; with luck it's got a 3" bellcrank and the builder used the outer hole; in that case you may be able to modify it for better control ratios without dire surgery.  But I would suggest that if you go that far you have a plan for what you'll do if you find an itty bitty bellcrank in there.

[Dave Hull]

What is likely more important hasn't been discussed at all:

1. Will it pass a 10-G stunt pull test?  If it is that old, and was assembled entirely with Ambroid, and stored forever, it may still look good on the outside, but.... Strange noises and pops during the pull test would move this back into a "wall hanger" category for me, unless I was committed to rebuilding it--which might be worth it if it is still straight.

2. If it passes a pull test then just take care of the control sensitivity concern by hooking up a handle with appropriate line spacing. Deflect your wrist about what you are used to, and see if you can get 25 degrees or so on the elevator. You don't need to stretch out full lines. Just rig something up close so you can watch. If this looks ok, then

3. Check to see that the flap-to-elevator rigging makes sense. Either equal, or less flap than elevator.

4. Check to see that the control friction is reasonable. If it is stiff, see if lots of repeated motion begins to free it up. If not, you're going to have to find the problem(s) and fix them. Also check for control system slop. Leadouts to flaps. Flaps to elevator.

5. Check the rest of the trim. Old, stored planes often have warps. More so if silked and doped. You don't want to destroy a nice looking wall hanger because the wing looks more like a propeller. Part of the trim check should include CG and the leadout location.

I've worked on quite a few OPPs (Other Peoples Planes) in the last few years and am continually surprised by oddities that a builder will incorporate. Whether by mistake, or by incorporating a novel idea to "improve" something that used to work well....  And don't assume that quality woodwork means that the controls installation will be correct, or of equal quality. I've worked on a couple planes that might have been built by pure free-flight guys. The woodwork was really nice, but the controls were non-conventional (to be charitable) and virtually guaranteed an impending crash.

You can do all of the above in just a few minutes, and it will tell you how much potential your gift has.

Dave

[Lyle Spiegel]

did not see any mention of the "differential" control setup that was part of original Veco kit. As i recall there were two pushrods , one for each flap, but the flap horns were different for inboard/ outboard, so amount of deflection was different. If you are going to install the control, you may want to revise to modern style setup.

[Al Takatsch]

I love the look of the Thunderbird and Smoothie. That Elliptical wing is eye catching.

I had a Smoothie that flew like heaven on wings with a .35 Max S. Almost overpowered.
I would think the Thunderbird would fly great too, don't put a bigger motor on it. That would alter its balance and need tail weight.

[Dwayne]

On further inspection the controls are very smooth with no play but I'll check with the builder to see if he remembers what he used to glue the bellcrank in. 
Lyle: The flaps move  about 25% of the elevator. I really like the looks of the natural wood and red covering so I think all I'm going to do is clear it an fly it.
Prop suggestions for an old school Enya 29?
Tank size for a 7 minute run?

[Steve Helmick]

That's a T-bird Mk.1, so it does not have differential flaps (a good thing to not have!)...that came along with the Mk.11 or 1959/1960 variant. The wing area of the Mk.1 is around 595 sqinches, while the Mk.II was advertised at 610 squinches.

On the one hand, it'll be a fun sport model, but not if it screws up your feel for more serious models in your stable. Maybe take it out on New Years Day to fly, so you'll have plenty of time to forget about it? I'd be interested in whether you find the engine easier to start upright, or if you find it helps to turn it upside-down to improve the starting.    Steve

[BillP]

Nice plane. I would fly it before cutting anything. That's a TB-1 which had an offset wing but I can't tell if yours was built that way. I scratch built one with offset and thought it was a wonderful flyer on 60' lines (at sea level)...until making it a lawn dart. Instead of a full cowl I did an exposed engine for easy access and used a McCoy 35 first and then a McCoy 40. If memory is right weight was 36 oz + fuel and no trim weight required.