Simple 1/12 Scale Bristol Scout C for Electric

[OZPAF]

What a neat effort Andy. good luck with it.

[AndyB]

Ok, so it's sort of finished, for a very flexible value of "finished".

It's in a suitable state to try and commit aviation - it's missing a pilot, windscreen and rear fuselage serials but if it's going to pile in at the first attempt then I won't have wasted any extra time adding the details.

It's also rather heavier than hoped at 9.57 oz, including 1.7 oz of nose weight. I think it'll probably fly with the KP02, but the power system will probably be working quite hard.

All I need to do now is to find some long grass and a calm morning to do some test glides...
 

[Squirrelnet]

Looks great Andy, nice model

[OZPAF]

Well good luck with the trimming Andy. hope you find plenty of KK grass.

John

[TheLurker]

Nice.

[AndyB]

After waiting - quite literally - for the grass to grow, I can report that the device flies, and it actually looks pretty good in the air; see pic #1.

It needs a lot of side and down thrust (and yet another motor mounting plate) and it turns out that the rudder is VERY sensitive. Part of the reason for this is that it's an all-moving rudder, but the original published plan (which I didn't check) has a larger-than-scale rudder which complicates matter further; a titchy-tiny adjustment makes the difference between a tight left turn and a wide right turn which of course eventually ends with it spiralling in.

Also, the motor is working very hard at 100% throttle, so if I want to add a pilot and other details I really need to get rid of some of that nose weight.

I'm therefore going to bite the bullet and change the tail surfaces for what I hope will be much lighter built-up, more accurate replacements - see pic #2. I did consider 1/32" sheet core tail surfaces but that would cost weight that I might not be able to afford, and I am assured that an ordinary structure with laminated outlines (3 1/8" x 1/32") will be Ok if I'm careful.

The outlines seem to have worked out Ok (pic #3), even after a couple of hours soaking in hot water I had to persuade the laminations to bend around the really tight curves by indenting with a thumbnail on the inside; there are only a couple of minor c*ck-ups and I'm hoping that nobody will notice.

The plan is to cover them with Japanese tissue or possibly Dilley Jap because it seems to shrink less, followed by non-shrinking dope, banana oil and then a light airbrushing for the tailplane and the thinnest possible spray from some Humbrol Acrylics cans (because that's what the roundel colours are) for the rudder.

[dputt7]

Very nice work and glad to hear good flight reports. Jore your lighter tail unit allows less nose weight and you can finish the remaining details.

[AndyB]

Just done the tail surfaces (see pics), they're not quite finished because I need to leave them and then come back to them otherwise I won't notice the high spots that need sanding off.

Think I might try some Dilley Jap tissue (assuming that it's in the cupboard I think it's in) as it's almost the right colour (=less paint required) and doesn't shrink much. But it needs applying with dope and thinners so it'll take a bit longer than using a glue stick.

[AndyB]

New tail surfaces are covered with Dilly Japanese tissue, steam shrunk, one thin coat of non-shrinking dope and one coat of banana oil - so far, there's not really much (if any) sign of a warp.

The covering was fine until the elevators were hinged (just visible in the first pic), when a few slack areas and wrinkles appeared. I've now patched the worst and will live with the rest because time and tide, etc...

[Squirrelnet]

Looks really good Andy, lovely structure. How does the weight compare to the old sheet versions?

[AndyB]

Just finished painting the tail surfaces; total weight is 7.0 grams which I'm quite pleased with, one of the elevators has warped but I'm not too bothered about that because it's a moveable surface.

Looks really good Andy, lovely structure. How does the weight compare to the old sheet versions?

Not sure because I've not removed the old tail surfaces yet, but the new tail surfaces are less than a quarter of a gram heavier than the old, non-hinged, pringle-shaped built-up tail. If I had to guess I'd say I've probably saved about 5 grams at the tail, so that's ~20+ grams out of the nose, so I should be Ok to add a pilot and a few minor details.


The Vallejo paints always seemed to cause temporary wrinkling on tissued surfaces, I assume that the alcohol/water thinners are the cause. Going forward, I don't think I'll be using acrylic paints again unless they're thinned with cellulose; do-able with Tamiya paints, not sure about Vallejo. It's probably easier to use Xtracolour thinned with cellulose thinners as other people do...

[AndyB]

Looks really good Andy, lovely structure. How does the weight compare to the old sheet versions?

<smug_mode>The new ones are about 6 1/4 grams lighter - see pictures </smug_mode>*

That's about an ounce of nose weight that's no longer needed. I'd better make a start on the pilot and final details.


*This is, of course, a Red Dwarf joke...

[TheLurker]

Sorry, fresh out of kippers.

[AndyB]

Almost finished the pilot (Captain Rupert Cordingly-Smythe RFC); not my best work as I'm a bit out of practice, but he'll do. Just needs a mist of varnish to finish him off.

Remaining job list is:

• Fuselage numbers (look to be freehand on the original, might do the same)
• Windscreen
• Step to cockpit, both sides
• Assembly
• Re-balance