Author Topic: Flexi-wings and Coverings (Read 2156 times)

Tim Wescott · « **on:** June 14, 2011, 07:33:19 AM »

A friend gave me an ARF Flight Streak, which I've promptly ripped to its component pieces. I'm going to do a comprehensive rebuild on it.

Those wings are flexible without covering. Does anyone have any estimates of just how much torsional rigidity is lent to a wing by different coverings? Obviously a film covering is going to go on quickest, may be lightest, and that may even be the way I go. But I'm considering either Polyspan or silkspan, and dope, and would welcome comments and suggestions.

john e. holliday · « **Reply #1 on:** June 14, 2011, 07:52:40 AM »

What do you consider flexible? Seen the pics of the plane. If it truly is the ARF version, replace the fuselage. Check all the control system. And cover the wing with what ever you want. If it flexes too much there may be some loose glue joints in it. Have fun with the rebuild.

Tim Wescott · « **Reply #2 on:** June 14, 2011, 07:59:32 AM »

I consider anything less than the rigidity lent by a D-tube wing to be "flexible".

It's truly an ARF version -- I was struggling to decide between just slapping a motor on it and flying it vs. replacing the fuselage when I noticed that there's no maple motor bearers -- just balsa sandwiched between plywood. That's what really made me get out the reciprocating saw.

Between crash damage that was hiding under the covering and an "oops" with the reciprocating saw I need to replace the top sheeting of the wing, so I'll probable re-do the bellcrank mount while I'm in there, and maybe replace the leadouts.

Mark Scarborough · « **Reply #3 on:** June 14, 2011, 09:23:12 AM »

MAN,, your harsh,,
Tim,, read my lips,, IRON ON FILM<< IRON ON FILM<< IRON ON FILM<<< IRON ON FILM<<<

did you catch that,,
IRON ON FILM,
serious, until you quit finding the ground do NOT silkspan,, a couple reasons for this,, yes the wing will be slightly,( or greatlyl) more flexible with iron on, HOWEVER this can be an asset,, when you smack the ground, I mean, uh ,,, land before you run out of fuel,, a wing built like this,, or the twister,, will flex, sometimes ripping the monokote/ultracote/ iron on finish. This will absorb a great deal of the energy and most times allow the wing structure to survive better. silskpan will transfer the load to the structure, typically turning it into splinters,, so let me restate,, IRON ON FILM,,
You see my planes, I can paint, I love to paint, sanding is zen to me,, but I learned my lesson early,, IRON ON FILM, until you go a season without crashing,, THEN silkspan, and it wont be on a flight streak,,

Did you get the point there Tim,, no? ok, let me put it simpler for you,, ( Its the whole engineer thing ,, just want to make sure you get it,, )

IRON ON film,,
and you could email Dan, he has a couple minor things to say about flight streaks,, if you catch him on a good day, sometimes he will even share them with you ,, lol

Tim Wescott · « **Reply #4 on:** June 14, 2011, 10:39:16 AM »

OK. It'll be quicker, too.

I was thinking of using it for practice on silkspan, because it's been a long, long time since I've done a silkspan and dope finish. But I'll let that wait -- or do up an RC plane in silkspan & dope.

Mark Scarborough · « **Reply #5 on:** June 14, 2011, 10:57:25 AM »

Good choice,,
did you settle on the 25 for power?

Tim Wescott · « **Reply #6 on:** June 14, 2011, 10:59:35 AM »

I can't say (because if I do, you'll repossess the airplane).

I do like the sound of Leo Mehl's Fox.

Mark Scarborough · « **Reply #7 on:** June 14, 2011, 11:04:21 AM »

dont you dare!!!!!!

if you do use the fox, remember the popsicle trick, it is a profile after all,, and dont forget the shims under the mount lugs ,, and,,
sigh
You REALLY should consider a 25,,, better run, less headache, less castor on the plane when your done, less vibration,, less concerns about the airframe disapearing out of your car (for using a fox 35,,) and better flying,, its also a good idea to give you more needle time on the engine you use in your primary,, instead of learning a new system with the fox,, but hey, if you LIKE abusing yourself,, whatever,,

Tim Wescott · « **Reply #8 on:** June 14, 2011, 12:35:18 PM »

Of course I couldn't possibly be yanking your chain.

Mark Scarborough · « **Reply #9 on:** June 14, 2011, 01:49:02 PM »

Tim to suspect that you are yankin my chain would imply that you have a sense of humor, and we both know engineers dont HAVE a sense of humor,, cause it cant be calculated,,( incorrectly )

Russell Shaffer · « **Reply #10 on:** June 14, 2011, 02:55:40 PM »

Mark is RIGHT!!! A Flite Streak wing is stiff enough as designed - do not modify it to a D tube or put on LE sheeting and do not cover with anything but film. It will take an amazing amount of abuse and is easy to repair - get that, don't rebuild it when bent, just repair it. Cut out the torn covering, patch the broken ribs, and iron a patch over the cut out. You don't recover the wing or sand and repaint the fuselage or the tail feathers. Just patch it and go again. Works for me.

Mark Scarborough · « **Reply #11 on:** June 14, 2011, 04:30:11 PM »

Russell,
it sounds like you know this first hand,, hmm experience maybe? LOL

Steve Helmick · « **Reply #12 on:** June 14, 2011, 04:42:03 PM »

Without moving flaps, I think the FS ARF wing is stiff enough. If you were to make the flaps work, and lengthen the TMA, then you might have justification for your worry. Definitely check for wing structure damage before you button it up with new film. Use a .25!

Steve

Russell Shaffer · « **Reply #13 on:** June 14, 2011, 06:31:22 PM »

Just squirt Gorilla Glue on the broken spars and shove everything back together. Wait 24 hours and goober over the rest, then fly. Gorilla Glue foam makes a fine profile wing fillet.

Tim Wescott · « **Reply #14 on:** June 14, 2011, 06:33:01 PM »

Quote from: Steve Helmick on June 14, 2011, 04:42:03 PM

Without moving flaps, I think the FS ARF wing is stiff enough. If you were to make the flaps work, and lengthen the TMA, then you might have justification for your worry. Definitely check for wing structure damage before you button it up with new film. Use a .25! Steve

I'm replacing a considerable amount of wood in the center section for just that reason -- each repair was, in and of itself, a reasonable thing. But together, there was quite a hodge-podge of epoxy, CA, and popsicle sticks.

I'm coming of a period of very thin employment, and don't want to spend a lot on the hobby. While I have a spare airframe (I was given this because I thought #1 plane was toast, then realized at the 11th hour that it was repairable), I've only got one FP 20. But I do have an Engine that Shall Not Be Named, and a paranoia about breaking my FP 20. So I think I'll see if I can set the plane up to accept both an FP 20 and The Unmentionable. So if I should happen to prang both the Waiex and the Skyray I'll have this with an FP 20 -- but if I splat the FP 20, I'll have this with, well, an engine.

Howard Rush · « **Reply #15 on:** June 14, 2011, 07:57:44 PM »

I was impressed long ago by how silkspan-covered Flite Streaks shatter like glass.

Mark Scarborough · « **Reply #16 on:** June 14, 2011, 08:06:36 PM »

Tim, contact me offline about your engine situation,, perhaps there is a workaround for your current algorythm,,

john e. holliday · « **Reply #17 on:** June 15, 2011, 08:29:59 AM »

Tim are you saying you need a good dependable .25? Even tho I am a Fox man and have used them since the early 60's, I like the OS and Brodak .25's. Of course each one of mine is a little different on each plane. One runs only on muffler pressure. The rest no pressure. If you need an engine, just PM me.

Peter Nevai · « **Reply #18 on:** June 15, 2011, 11:18:14 AM »

Quote from: Mark Scarborough on June 14, 2011, 09:23:12 AM

MAN,, your harsh,,
Tim,, read my lips,, IRON ON FILM<< IRON ON FILM<< IRON ON FILM<<< IRON ON FILM<<<

did you catch that,,
IRON ON FILM,
serious, until you quit finding the ground do NOT silkspan,, a couple reasons for this,, yes the wing will be slightly,( or greatlyl) more flexible with iron on, HOWEVER this can be an asset,, when you smack the ground, I mean, uh ,,, land before you run out of fuel,, a wing built like this,, or the twister,, will flex, sometimes ripping the monokote/ultracote/ iron on finish. This will absorb a great deal of the energy and most times allow the wing structure to survive better. silskpan will transfer the load to the structure, typically turning it into splinters,, so let me restate,, IRON ON FILM,,
You see my planes, I can paint, I love to paint, sanding is zen to me,, but I learned my lesson early,, IRON ON FILM, until you go a season without crashing,, THEN silkspan, and it wont be on a flight streak,,

Did you get the point there Tim,, no? ok, let me put it simpler for you,, ( Its the whole engineer thing ,, just want to make sure you get it,, )
IRON ON film,,
and you could email Dan, he has a couple minor things to say about flight streaks,, if you catch him on a good day, sometimes he will even share them with you ,, lol

Funny thing about the Kotes (mono and ultra). I've been using them since they came to market and with extensive crash testing I cam across 2 modes of failure.

1. The covering along with the woody parts shattered equally, (actually had litte scraps of covering blow around)
2. The bag of balsa failure mode, where the covering remained more or less intact but ended up a very neat balsa scrap container.

Of course when I put it in, I PUT it in. No smack the ground at a shallow angle of attack, it is lawn dart all the way!

One thing to remember about the films though, They HIDE DAMAGE very well, You need to thoroughly examine the model after each abrubt mating with tera firma. Externally everything may look A Okay, but stuff inside may not be doing so well (see failure mode #2.

BTW. Ultracote is a tad stretchier than Monokote after applied, but Monokote bonds more tenaciously, pick your poison.

Tim Wescott · « **Reply #19 on:** June 15, 2011, 12:07:39 PM »

Quote from: Peter Nevai on June 15, 2011, 11:18:14 AM

BTW. Ultracote is a tad stretchier than Monokote after applied, but Monokote bonds more tenaciously, pick your poison.

My recent experience with Monocoat is that it doesn't shrink at all as well as I remember from days gone by. I've got a wrinkled RC trainer to prove it. I may try it again, though, as I've got (I think!) enough white to do the wings and tail, which should match rattle-can white OK and be a nice base for trim.

Russell Shaffer · « **Reply #20 on:** June 15, 2011, 01:05:28 PM »

Very good point about the hidden damage. If you have to buy film, consider the semi transparent stuff. Some people use it to show off their fine workmanship, but I like it because I can see the broken structure underneath. And it does look nice in the air.

Peter Nevai · « **Reply #21 on:** June 15, 2011, 03:59:53 PM »

Quote from: Russell Shaffer on June 15, 2011, 01:05:28 PM

Very good point about the hidden damage. If you have to buy film, consider the semi transparent stuff. Some people use it to show off their fine workmanship, but I like it because I can see the broken structure underneath. And it does look nice in the air.

If you use the transparent colors, make sure you vacum out the airframe well, else all the dust and balsa chips will end up coating the insides of the covering. But you can do all sorts of neat stuff with the tranparents. It gives you a whole extra domain to show off your artistic skills.Stick a photo of the family inside, do fancy scroll work on a couple of ribs, For a really wild effect get some white leds mount them in acouple locations in the wing panels and with a couple button cells, or a AAA battery or two the trans covering can be made to almost glow.

Tim Wescott · « **Reply #22 on:** June 15, 2011, 05:04:18 PM »

Nah, given the quality of this particular airframe I want to use opaque. Given the flak I'm already getting for working on it at all, I'm not going to do any aesthetic corrections to the structure, either.

Mark Scarborough · « **Reply #23 on:** June 15, 2011, 05:24:59 PM »

perhaps given the nature of the airframe, something along the lines of a patchwork quilt could be inspiration for a color scheme,,
Just sayin,,,,,,

Tim Wescott · « **Reply #24 on:** June 15, 2011, 06:43:16 PM »

I thought that's what I took off?

Having been razzed for trying to redo the airplane at all, I'm feeling the peer pressure to do something dull and boring.

Peter Nevai · « **Reply #25 on:** June 15, 2011, 07:04:18 PM »

Oh contrare, yellow wings, black fuse, bladder tank, fox 29X, 9X8 prop and go combat stunt! this way when it packs in, balsa dust will be all that remains, but it'll be a thrill a secomd till then. Name it HELL BENT!

Tim Wescott · « **Reply #26 on:** June 15, 2011, 07:11:27 PM »

No Fox 29X. But I have a Fox 40 that I could use. It may even attain the "balsa dust" stage before it hits the ground, then.

Peter Nevai · « **Reply #27 on:** June 15, 2011, 07:23:20 PM »

Quote from: Tim Wescott on June 15, 2011, 07:11:27 PM

No Fox 29X. But I have a Fox 40 that I could use. It may even attain the "balsa dust" stage before it hits the ground, then.

How Diabolical!, Gotta love a guy who ups the ante, and I was thinking perhaps Fox 36X. 52 foot lines of course.

Muhahahaha!