Sometimes you really shouldn't read threads like these. I just ordered a Shoestring should be here Wednesday the 19th. Now the question is do I call in sick Thursday so I can fly it on the weekend?

I usually build but this winter things didn't work out, too much time spent away from home. I'm very much impressed by what I've read. I plan on pinning the firewall, glassing the wing and beefing up the landing gear. Anything else?

There were some posts previously about not gluing the cockpit onto the wing but using pan head bolts instead. What are the advantages to doing this?

Thanks,
John

Jnorton,

I believe it was suggested using pan head screws to hold the canopy to the cockpit and not the cockpit to the wing. I usually use pinstripe to attach my canopy but on the Shostring the fit wasn't as good as it could be causing the tape to pull up along the sides from heat and stress. If I had known this I would have put some hardwood blocks on the inside of the cockpit piece and added screws to help hold the canopy in place, However, now that the cockpit is glued to the wing I can't get to the inside of the cockpit anymore along the entire edge of the canopy. I suppose if you use the glue method, something I don't as I always make a big mess, this wouldn't be useful.

Jeff

Thanks, that makes more sense!

Actually, I believe I described how the cockpit is mounted on my plane earlier. Rather than gluing it on the wing, it is separate, held on by a dowel protruding from the front going into a mating hole in the former on the fuse, and a screw going through the top sheeting and stringer and into a wood block mounted on the rear compartment former. A rectangular hole was cut into the bottom/back sheeting to accomodate the wood block when the cockpit is mounted. I can post pictures if any of this is not clear.

As to an advantage of this, I really don't think it's much either way.

Rick,
Please post a picture! I am really looking forward to assembling this plane and I want to make it the best that I can.
Thanks,
John

this is a really excellent airplane.

i had a shoestring and flew it almost every weekend for two years. after a while I got cocky and crashed it on an aggressive (short) landing approach and thought it was done, but i had the time and bothered to fix it and flew it again.

this is a super flying airplane which will really teach you taildragger handling, you can do nice wheel landings and it will even knife edge really well. I only had an OS 61FX in it and that was all the power she needed. not overpowered but plenty of vertical (not unlimited, but plenty while flying with speed) and could do nice large loops of almost any size.

it flies perfectly whether right side up or inverted. will also fly remarkably slow and graceful for a model of a real pylon racer.

It tended to nose over easily on our bumpy grass field, eventually i ditched those pretty wheel pants and went to some larger wheels which helped, but you still have to pay attention to the nose while taxiing slow, and consciensly hold the tail down. if you're taxiing down wind with up elevator to hold the tail down, the wind can just lift your tail right up on you so you have to mind the throttle and keep prop wash over the tail to hold it down. maybe this is typical with tail draggers.

Hi Guys,

Just brought one of these, can i ask how you line up the wing mounting holes on the cockpit which you have to drill to the inside of the fuse ? is thier an easy way as i dont want to make the holes too big.................... also can i ask how you go about strengthining the landing blocks as ive read on this thread its advized................. ie: what thinkness and what kinda of wood etc ? or can i just add more epoxy ?

Also whats the best size engine for this ?? 2 stroke ? 4 stroke ?

Thx for any imput

DragonHeart,
Others have used .61FX to .91FX 2 strokes or .71 to 91 4 strokes. I'm going to use a .61 FX and a Bisson muffler on mine as I'm using it as a "Sunday Flyer". Can't help you on the rest as I haven't got it yet.

Do a search for shoestring. Be sure to change the search to subject only as shown.

I noticed most of your previous postings are mainly in the beginners section. Be advised that this is not what I would consider a good second airplane. Be sure and get help flying it. I would really recommend something else for now. It's fast and if you screw up the landings the gears coming out.

John

I have just about had it with that TT91. I fought with it through over five tanks of fuel, and the best I can do is too rich at idle with a full tank and at the same time too lean near empty. The lowest reliable idle I seem to be able to manage is about 2600. I felt this was high, but I thought I could handle it.

So this afternoon, I took it out to the field and took the plunge. Had a bad time with my Cub and a malfunctioning throttle, and after two hours gave up on that and decided to try the Shoestring. Taxiing turns out to be a real bear; the way it balances over the gear, anything below half throttle invites a noseover. After nosing it once and stalling it out two other times, I finally figured "to heck with it", and once I had it rolling I just throttled up and pulled back, and off it went.

Not sure where I went wrong with the elevator, but even at full down trim it was still climbing at half throttle. Flew for a while that way, did some loops and some rolls; man is that thing fast! Needs rudder in the turns. And now I know why the guy didn't put the markings on the bottom of the wing - it's *real* easy to lose orientation when the top and the bottom are identical.

About half way through, I decide to try some approaches. This is where the fun starts. I throttle back, come around on base at my usual altitude, cross the threshold a little high and try to chop the throttle, and find to my dismay that it was chopped! It flies by me at idle setting about 10 feet off the deck, not showing any tendancy to want to slow down before it reaches the end of the field. I only need one click of throttle to continue flying at a comfortable speed; at this point I realize I'm in trouble, the thing isn't going to stop. I try several approaches, each one longer and lower than the last, which were equally as unsuccessful. Then, I try just flying it onto the runway, hoping the grass will slow it enough to stop it, buy after a 150-175 foot rollout, it's clear each time it would hit the high weeds at 30mph, so I gun it at the last minute and go around.

I get desparate and try reprogramming the end point on my throttle channel lower, but it still doesn't seem to be slowing any more. On the fifth attempt at landing it this way, I pull up again and turn to go around, and just as I get downwind the engine sputters and quits (on, did I forget to tell you my timer went off on attempt #4?). NOW the silly thing wants to come down, but I'm 100 feet from the runway edge and 25 feet off the ground, turning toward a quartering wind. Needless to say, I didn't make it back. I came down fairly hard in the high weeds, but flat and almost level.

Thanks to all the recommendations to reinforce the gear mount from here on RCU, I had glassed the mount area with 6oz. cloth. What I found after trudging out through the weeds is that I had slightly bent the left gear, and that's it! Thanks guys! Sorry, there were no pictures - my photographer (my daughter) was out on a school project with her mom today.

I tried this flight with a MA 14x8; I guess next I'll try a 15x6. I'll also spend yet another evening battling with the mixture screws. I figure I gotta get at lest 2200 reliably or I'll be dead sticking it again. But overall I was pleased with the performance; it'll be a blast flying this plane when I know I can get it back on the ground!

John, I'll try to post pictures of the cockpit mount tomorrow night.

Thx JNorton for the reply

Yes most of my posts have been in the begginers forum but this is my 20'th plane (and all 20 still intact ) and ive been flying for a year , soo far froma beginner im used to flying warbirds but i saw this ShoeString at a show and was on a look out for a plane with speed which flew nice and from all the comments in here about the ShoeString it just had to be that

Im thinking of getting a OS91 Four Stroke to put in, will that fit in with no problems ?

Rick,

I guess it was in another Shoestring thread where it was suggested to screw on the canopy. I must of missed the suggestion on the cockpit.

As far as the nose over goes, mine has never even come close. Are you sure the gear isn't installed backward?? We recently had a guy at our field having the same problem with his Shoestring. Turns out he tried to balance the plane on his fingers and was off enough to cause it to nose over on roll out but still fly okay. With that light tail I guess it's real sensative to balance.

Jeff

Well, I have been following this thread with great interest. I have decided to ressurect my Shoestring from the stock pile of broken planes in my shop. I have begun the cumbersome task of rebuilding the fuse where it broke at the front end of the wing saddle. I will have to refabricate the ply sides stringers. as well as the 2nd and 3rd formers. Also, the gear area will need a complete refit. My recommendation to other Shoestring owners, "Never hit a ditch head-on during roll-out.

Jeff, nope, neither of those are it. I was real carefull about mounting the gear the right way after seeing Primodius' posting earlier ([link=http://www.rcuniverse.com/forum/upfiles/86063/Nl29942.jpg]here[/link]), so mine is definitely mounted with the swept edge facing back. But I agree, it sure acts like the gear is too far back. When I taxi at low throttle, the tail hops up and down like a bunny rabbit. A power on landing should be a real adventure...

I balanced mine with a Kollercraft Pro Balance, and it might be just a couple degrees nose heavy balanced right on the mark, but it's real close. Indeed, the problem with the elevator trim I had would indicate it's balanced plenty far back. I was just debating whether I could shim the gear mount to tilt it farther forward; I may try that.

Rick,

If I remember right you didn't put this plane together. Do you think mounting the engine too far forward would cause more nose overs? I realize you would compensate by adding tail weight but would the added length in front of the gear be more than the tail weight could keep down on the ground?

Your elevator trim problem does sound worse than mine. I found that my horizontal stab is a few degrees negative to the wing which would require down to compensate. I tried adding a few washers behind the top of the motor mount and it seemed to lessen the amount of down trim I needed to fly level. It also did not make the plane balloon when I cut the power. With the sideways mount I thought I might have accidently gave it some up thrust when I mounted the motor. I bought a new motor mount to try and put in some more down thrust as spacing the top of the mount out really screws up the cowl relationship to the spinner. Do you know what a typical amount of down thrust should be? I'm going to check it with the incidense meter this time to be sure where it's set.

Jeff

Well guys after listening to you I'm going to make sure the incidences are correct before I glue the stab. I'll also check the wing and engine mounts. I'm thinking of -2 down on the engine mount, 0 wing, 0 stab. Do this sound about right?

The Shoestring should be here Wednesday. I stopped at the LHS today and purchased a roll of Cub Yellow, 45 minute epoxy and fiberglass. Feel like a kid with his nose pressed up against the window - just a wishing and waiting!
John

Jeff, Yeah, you remember right, I didn't build it, BUT you forgot that one of the big changes I made was to move the engine (and the cowl) BACK 5/8". The thrust washer WAS right where the instructions called for (6 5/16" from the firewall or something, I'm not at home now and can't check), now it's further back than called for. I did this because as it was the balance was so drastically noseheavy I needed to do something drastic.

Interesting that you mention the change of thrust line; adding down thrust would help with the trim and also with the cowl alignment - as with others who have posted hear, when the cowl markings are aligned with the fuse, the thrust washer (and therefore the spinner) are way out of whack with the cowl, with nearly a 1/4" gap at the bottom with 1/16 at the top. I think I'll try that first.

By the way, according to the GP web site, the incidences should be 1 degree positive wing, 0 degree stab, and the thrust 2.5 degrees down, 2 degrees right. I'll have to check mine, too.

Thanks for giving the incidences Rick. After you said they were on line I searched and finally found them. Why is something so important given so little attention. Incidences are not in the manual, nor are they on the web page that describes the airplane, they are in a footnote on the bottom of the airplane index. No wonder I missed them!
John

Guys'
I think your on the wrong track here. The engine mount, thrust washer and cowl alignment shouldn't be off and the stab and wing are factory set. I found when I mounted a YS 110 inverted that there where four possible variations of engine mount and engine. Engine on top or bottom of mount and the engine mount itself can be turned over so I had to figure the right combination to get the thrust washer and spinner centered on the cowl. Once this is accomplished you will have the factory settings which are correct. I think the reason they don't give them in the basic instructions is that you don't need them to successfully build this model.

As for weight, even with the YS 110 I was able to place the battery rearward and get it to balance fine. It slows down a lot for landing and flies very well.

Basin, did you mount your battery behind the wing? If not, your experience is substantially different than everyone else who has posted here with this model. And if you search around, you'll find other threads where at least two other fellows experienced the same cowl misalignment my plane shows. That seems to be a GP theme, as I've noted the same problem exists with the Lancair.

Rick,
As I said in my post "I was able to place the battery rearward" so yes it is behind the wing. Also, a few other people having the misalignment problem makes sense. The first way I tried mounting the engine it sat low and the spinner didn't match the cowl. I ended up flipping the mount upside down and mounting the engine with the top of the lugs (which were on the bottom because it was inverted) resting on the mount. This solved the problem with the YS 110. As I mentioned there are four combinations possible to get the cowl and spinner to line up correctly and you have to experiment to see which way works best with your engine.

Basin, since I just bought a YS91 to replace the finicky TT91, can you post a picture of your engine installation?

Rick,

Thanks for the incidense numbers! I didn't know they were available either. Just from eyeballing mine I would say it has no down thrust on the motor at all.

I get what Basinbum is saying when mounting the motor inverted but I mounted mine sideways. There isn't too much adjustment for up and down using that method. You can only twist the motor within the mount. Side to side the motor fits fine.

Just fyi..... I mounted my battery on a piece of plywood and slid it down behind the wing as far as it would go (4 or 5 inches I'd guess). Then I screwed the plywood with a couple of blind nuts to the block of wood that the wing bolts go through. I also put tail bracing on with 2-56 rods to get the Shoestring to balance correctly with my .91FX.

Currently, along with re-mounting the motor, I am mounting a larger fuel tank with a more flexible pickup tube rearward of where the original was installed. I'm having a lot of problem with the Perry pump sucking air below 1/3 tank as the pickup I had in there wasn't flexible enough to move to the front of the tank when in a dive. I was getting 7 minute flights at most with that combination before it cut out.

Unfortunately, the Shoestring is second in line behind repairing my 80" Cap's wing that I tried to high altitude land in a pine tree. Not much damage considering except for the $100 charge to get it down from the tree in one piece.[&o]

Jeff

Rick,
I built the plane for a friend so I don't have it here to take a picture. The engine sit's on top of the mount inverted so you are in effect putting the bolt through the bottom of the engine lug first, then the mount. Does that make sense? If it doesn't line up that way turn the mount over and it will.

Basin,

I'm not following your original mounting options premise. If flipping the mount over changed the relative angle of the engine thrust washer to the firewall, that would mean that the engine bearing surfaces (top and/or bottom) aren't 90 degrees to the firewall surface. I can hardly believe that's true. The problem as I see it is that if the cowl is mounted so that the paint lines up properly with the fuse, the cowl front surface is perpendicular to the datum line of the fuse, rather than parallel to the firewall (which I assume has the proper thrust angles built into it. This is definitely the situation with the Lancair, so it would surprise me to find it on the Shoe.

It looks to me that they forgot to put the downthrust in the firewall! Eyeballing my model, the right thrust is apparent, but there doens't appear to be any downthrust. Using the center sections (between the two main formers) of the wing saddle stringers (did you follow that?) as the zero reference, I measure 1/2 degree positive thrust (UP-thrust!) at both the firewall and the mount surfaces. Am I goofing this measurement up somehow?

The picture below shows my mount situation. This setup is academic, since I made the descision last night to ditch the finicky TT91 and replace it with a YS91AC. Another question for you Basin - is there a great deal more clearance required behind the crankcase of a YS engine (for the pump) than for a regular 4 stroke like mine?

By the way, I didn't say the other night that I had no problem handling the Shoe (other than getting the darn thing to stop ), even keeping over the boundaries of our recently reduced field airspace while taking it through all the basic manuvers. So I've pretty much convinced myself that I can fly anything at this point. Warbirds, here I come!

Just remembered my own earlier posting, that the wing incidence is supposed to be 1 degree positive, so that would make the firewall set at 1 1/2 degrees of up-thrust! Anyone else seeing this?