Author Topic: Shoestring repair (correction) (Read 32857 times)

Randy Powell · « **on:** June 19, 2011, 11:00:10 AM »

So, I built a Bill Simons Shoestring. The thing just wouldn't track no matter what I did (and trust me, I tried pretty much everything I could think of and some stuff I invented for the occasion. I couldn't get away from the idea that the problem was the stab. Checking with an incidence meter said it was was find, but by eye, it looked like it had a twist. As Conan Doyle said, once you eliminate everything else, what's left, no matter how improbable, has to be the answer.

So, I started building a new stab and elevators yesterday. I will cut the old stab out and put in a new one then refinish the tail and hopefully, that will do the trick and I'll have a classic plane again.

Ooops, forgot the picture.

Glenn (Gravitywell) Reach · « **Reply #1 on:** June 19, 2011, 12:29:42 PM »

If nothing else....its a beautiful aircraft.

John Miller · « **Reply #2 on:** June 19, 2011, 01:39:20 PM »

I'm happy to see you going back to work on this beautiful plane. I sincerely hope the end product turns out as well as you hope.

Air Ministry . · « **Reply #3 on:** June 19, 2011, 08:24:23 PM »

Now Id be sitting a pair of 6 x 2s or the like on edge on the bench at the hinge ,
and worrieing the rest with weights significantly opposite to the twist , to let it
ease back straight after a few days .But it could mess with the magnificent finish.

Unless its because the L.E. is a bit soft compared to the spar stiffness ?

NOW if you spent less time messing about with those aeroplanes , you might get the house finished . !

Randy Powell · « **Reply #4 on:** June 19, 2011, 09:04:51 PM »

Hey, the shop is sheet rocked. That's something. Some day I might texture and paint it ... or not.

I could try to warp it back to shape, but I'm not even really sure which direction. It's clearly not right, but what's wrong isn't. Seems just building another one is more likely to result in a decent flying plane. So, I built another stab and elevator and will cut out the old one, refinish the tail and we'll see what we have. The tail has already been hacked on with a marginal refinish. I'll do it right this time and hopefully have a good airplane at the end.

Air Ministry . · « **Reply #5 on:** June 20, 2011, 02:03:05 AM »

Priorities Right in both cases ! .

looks functional .

Not giving it a second chance to cause further trouble .

I never use ' rounded ' as in a 1/4 Rad. for L.E. on a 1/2 Stab.
Prefer the cathedral / airfoil bit, can be awkward to do though .

Randy Powell · « **Reply #6 on:** June 20, 2011, 09:30:21 AM »

This is the second Simons Shoe I've built. The first I just did a mild airfoil on the 3/8" stab. The second, this one, I followed the (incorrect) Flying models plane and did the triangular shaping. This is probably the problem or some variation of it. So the new one stab will have the gentle airfoil the first one had. That's by itself will probably solve the issue.

Neville Legg · « **Reply #7 on:** June 28, 2011, 03:37:29 PM »

What about a little more tail area, and a little less elevator? I remember trimming about 1/4" a time from the elevator, (solid sheet) on a stunt model, to try and stop it porpoising in level flight! I think about 3/4" came off before it calmed down. It would've been nice to have fitted a longer elevator horn, so I could've altered the throw, but it was a long time ago.

Cheers

Randy Powell · « **Reply #8 on:** June 28, 2011, 04:47:00 PM »

Neville,

Clearly, the basic design worked fine. The first one I built was a great flier. This one is clearly out of alignment or it's the shape of the stab. Or, who knows, something else. I figure just replacing the whole thing will more than likely fix the issue. We'll see, I have the stab cut out and the new one ready to go in.

jim gilmore · « **Reply #9 on:** July 04, 2011, 07:27:05 PM »

When you say i will not track, are you saying that you constantly need to make corrections in level flight to stay at the same height

?
When inverted do you constantly make the same corrections or are they reversed ?

Randy Powell · « **Reply #10 on:** July 05, 2011, 09:37:58 AM »

Jim,

The term "drunken sailor" comes to mind. It won't stay in a groove. Even when maneuvering, it takes constant corrections to keep it generally on track. It's just unhappy. Primarily out of alignment somewhere.

I have the stab cut out, but it went back on the shelf since I have some other projects that need attention at the moment. I'll get back to it soon.

John Miller · « **Reply #11 on:** July 05, 2011, 05:23:37 PM »

Quote from: Ty Marcucci on July 05, 2011, 04:33:04 PM

Uh, drunken sailors don't pitch, they roll. Been there, done that.

Didm't you spend some time on a Tin Can, or was it all on the Flat top luxury cruisers?

A plane flyimg like a drunken sailor would look like one of those old movie spots of an aircraft, with troubles, trying to land. Up, down side to side, with the throotle going up and down as well. What was that movie?

jim gilmore · « **Reply #12 on:** July 05, 2011, 11:12:28 PM »

Randy I was wondering ...
First question was if it tends to always roam the same direction....
As is drifting up....so you need to correct a little down to make it stay at say 5 foot.....and when inverted....
always sinking....in other words it is always moving away from it's track in the same direction...
Second thing to add to the problem is center of gravity.....
too tail heavy augments the planes ability to stay on track so that minor shifts get bigger....
I realize your a very advanced flier buy 1 thing I did very well even as an aircraft mechanics was being very good at diagnosing problems..often got me in trouble with management but most of engineering and inspection would listen and side with me...
Kind of why I got my A&P coming out of high school when many others could not pass it...

Randy Powell · « **Reply #13 on:** July 06, 2011, 01:13:01 PM »

Jim,

Well, the short answer is no. The pushrod has been moved a LOT. I've dialed in down thrust, It's had the flaps sealed and modified, I added rudder control (ala Al Rabe), and a number of other attempts to get the thing to track. I was able to get it to groove in level flight but then it wouldn't turn outside (this with a couple of degrees of down thrust and maybe 5 degrees of down elevator).

In the end, it was decided that the thing just had a warped stab and nothing for it but to replace it. Several notables in the area have had a go at it and all pretty much agree.

Steve Helmick · « **Reply #14 on:** July 06, 2011, 02:52:58 PM »

First time I've seen or heard a real description of what's going on with the Shoestrang, tho I've seen it fly enough. It sounds to me like it needs a sharper LE on the stabalizer, tho maybe this diamond airfoil is part of the problem. It does sound like an airflow attachment issue to me, not a warp. There are some temporary fixes for R&D, but since the old stabalizer is history, I'd suggest sharpening up the LE of the new one. I would like to look at the old one, if you haven't burned it yet.

Steve

jim gilmore · « **Reply #15 on:** July 06, 2011, 02:58:01 PM »

I actually had a direction I was headed...
So how much slop was in the elevator....or were the stab and elevator exactly the same .

Maybe you need the stab to sit in a slight void behind the stab..so to have a little area of non-effect...

Randy Powell · « **Reply #16 on:** July 06, 2011, 05:03:54 PM »

Zero slop. Ball Links. Diagnosis was an alignment problem causing the issue. It could be overcome by dialing in a ton of down elevator and some down thrust, but it wasn't fixing the problem, just masking it. The wing looks pretty good, but the stab clearly had a twist in it. So, I'm just putting in a new stab that is hopefully straight.

Mark Scarborough · « **Reply #17 on:** July 06, 2011, 05:29:39 PM »

Hey Randy,
why dont you just put in a new stab,, maybe that will help?

Randy Powell · « **Reply #18 on:** July 06, 2011, 09:37:08 PM »

Cute, Mark.

I have the old stab cut out. But I've been trying to make sure I get the RMD and the Slider flying right now. And I still need to work on the new sled. The Shoestring moved to the back of the line for now.

wwwarbird · « **Reply #19 on:** July 06, 2011, 09:37:33 PM »

I guess if it was me, I'd consider replacing the stab.

Mark Scarborough · « **Reply #20 on:** July 06, 2011, 10:50:22 PM »

dang Wayne,, not sure why I didnt think of that,, thats a great idea,, hey Randy, since you have the stab cut out, why dont you just go ahead and replace it,,

did you sort out the motor issue on the RMD yet?

Randy Powell · « **Reply #21 on:** July 07, 2011, 09:47:45 AM »

Mark,

Yea, pretty much. I put a new one in. Right now it's a pipe issues that I was going to see if it worked tonight. But now we have rain and it's supposed to continue until tomorrow.

wwwarbird · « **Reply #22 on:** July 07, 2011, 08:01:45 PM »

Maybe Mark has a stab he's not using from his 109?

Mark Scarborough · « **Reply #23 on:** July 07, 2011, 11:18:58 PM »

Wayne, that simply was not nice,, now my feelers are hurt, for your information the stab IS in use, it is currently acting as a remote dust collection device to help filter the air in my house, the wind is blowing and it stirs things up, so every surface I have helps get it out of the air,,

spare stab my tailpipe,, sheesh,, why I aughta,,,,,,

Bill Little · « **Reply #24 on:** July 08, 2011, 01:44:04 PM »

Yeah, Brother Randy, I think with a tiny bit of modifications, and since you already have the old stab cut out, you should just use the stab from Mark's 109 to replace the old one. he's not using it now........

Geez, when will I ever finish another model??

Love you guys!
Big Bear

Randy Powell · « **Reply #25 on:** July 08, 2011, 03:44:42 PM »

Come on guys, lighten up on Mark. He's working on it. Besides, it's a classic plane. I have to use a Shoestring stab.

Mark Scarborough · « **Reply #26 on:** July 08, 2011, 06:05:28 PM »

Randy ,thanks for defending me, lol,, The 109 will get done,, sooner than later

wwwarbird · « **Reply #27 on:** July 08, 2011, 07:28:31 PM »

Quote from: Mark Scarborough on July 08, 2011, 06:05:28 PM

Randy ,thanks for defending me, lol,, The 109 will get done,, sooner than later

Just tryin' to hold ya to it Mark!

And Randy, that 'String is an awsome looking model with a great paint scheme, it would look really goofy with a camo stab.

Randy Powell · « **Reply #28 on:** July 08, 2011, 07:54:17 PM »

Wayne,

Looks pretty goofy right now without a stab.

Randy Powell · « **Reply #29 on:** January 18, 2016, 08:00:56 PM »

So, I'm on the Shoestring again. Finally found the real reason it didn't track. Joy. I't coming along. New bellcrank and converting to electric. Should be fun.

Mark Scarborough · « **Reply #30 on:** January 18, 2016, 08:32:30 PM »

did you have a bellcrank issue Randy?

Randy Powell · « **Reply #31 on:** January 21, 2016, 02:08:15 PM »

Mark,

Well, apparently I went through a phase where I decided it was a good idea to wrap the leadouts normally and just bolt them to the top of the bellcrank. This, of course, tended to pull the bellcrank off center and put enormous pressure on the bearing. Over a surprisingly short period, the bellcrank's bearing is shot and the bellcrank starts to rock around, the leadouts bind at the bolt point and tracking goes to hell. Must have been a brain fart as I did this in three planes (and I've already said, WHAT WAS I THINKING). The Shoe, the Slider and the Ring. First two had the shot bearings and the control system has now been replaced. The third developed pavement poisoning due to a different engineering mistake though that one would have killed it eventually.

john e. holliday · « **Reply #32 on:** January 21, 2016, 02:13:57 PM »

Well we still live and learn.

Randy Powell · « **Reply #33 on:** January 23, 2016, 09:31:44 PM »

So, all day fitting electrics in the nose. Couple of false starts in figuring out the battery hold down. Think I have it now. Should be able to finish that up tomorrow and get back to finishing the beast. What fun.

Randy Powell · « **Reply #34 on:** January 24, 2016, 07:45:05 PM »

oK, it's ready for primer. Right after I put on the fillets. So, it's now ready for primer. Only just about ready.

Randy Powell · « **Reply #35 on:** January 25, 2016, 09:22:41 PM »

OK, here's a pic.

wwwarbird · « **Reply #36 on:** January 25, 2016, 09:30:59 PM »

Looks really clean, did you sand it all the way down or use some sort of stripper?

john e. holliday · « **Reply #37 on:** January 26, 2016, 09:22:02 AM »

With this being electron powered, are you going to test fly before spending all that time on a finish?

Mike Haverly · « **Reply #38 on:** January 26, 2016, 10:09:52 AM »

Quote from: john e. holliday on January 26, 2016, 09:22:02 AM

With this being electron powered, are you going to test fly before spending all that time on a finish?

Why? Electric power is way more predictable than a wet system.

Randy Powell · « **Reply #39 on:** January 26, 2016, 01:18:27 PM »

Mike,

I think he was thinking about the flight issues I had with it. I'm pretty sure I have them fixed.

Wayne,

I used a stripper and took it down to the wood, did some repairs, replaced the stab and elevator, replaced the bellcrank, converted it to electric and am now finally ready to finish it.

It will be a sort of cream, red, a bit of yellow and black.

I'll try to post some pics tonight. Includes some in process stripping pictures. It was a pretty plane and was a shame to strip it down to bones.

Bill Morell · « **Reply #40 on:** January 26, 2016, 01:30:27 PM »

I take it you are done with nitro?

Randy Powell · « **Reply #41 on:** January 26, 2016, 04:43:47 PM »

Bill, not sure. We'll see. I haven't sold my wet motors. And I will probably use them again.

Mike Haverly · « **Reply #42 on:** January 26, 2016, 05:40:14 PM »

Yes, Randy, that was mostly tongue in cheek. I also think you're probably under the gun to get finished for upcoming contests. It's not like we have a lot of good weather to go out and test unfinished airplanes anyway. No disrespect meant to Doc.

As far as wet power, the only engines I sold off was my big stuff, and that was to help finance my electric adventures.

wwwarbird · « **Reply #43 on:** January 26, 2016, 09:00:10 PM »

How do you use a stripper and not mess up the covering?

john e. holliday · « **Reply #44 on:** January 26, 2016, 10:04:52 PM »

The reason I asked was I remember Bobby Hunt posting about test flying his creation before finish.

Randy Powell · « **Reply #45 on:** January 27, 2016, 10:58:27 AM »

Wayne, I didn't. I stripped it down to the wood. It needed some other repairs and so that was just as well. Here's a couple of pictures. I even pulled up the fillets.

wwwarbird · « **Reply #46 on:** January 27, 2016, 06:25:06 PM »

Was it stripped using the "Dad's" product then?

I kinda hope you recreate that checker treatment on the tail. I'm not usually into the checker thing, just because it's seen so often, but that treatment was cool.

Randy Powell · « **Reply #47 on:** January 28, 2016, 12:20:01 PM »

Wayne,

This was done with something called Zipper Stripper. But it's basically the same as Dad's or Jasco. I got it at Home Depot or Lowe's I think. Worked fine.

Randy Powell · « **Reply #48 on:** January 31, 2016, 07:40:40 PM »

OK, fillets are on, the thing was shot with filler and is now sanded (and my wrists are killing me after 8 hours of sanding) Just need to go back over it with some 400 wet then a coat of clear to lock it down then it is one to base color. I will get this sucker done for VSC. I will.

wwwarbird · « **Reply #49 on:** February 01, 2016, 06:47:15 PM »

Electric at VSC?

Lookin' pretty slick though...