Interested in getting the GP Shoestring; don't want to butcher the cowl; what engines have guys tried that will fit in cowl without too much cutting; prefer a Four Stroke. Thanks Doug.

Hi,

I fly mine with a Saito 91 Fourstroke, which i thinks perfect for this plane.......... and belive me it is FASTTTTTTTTTTTTT !!!!!!!!

Did you have to cut the cowl up a lot to fit that Saito 91?

Not really but i cut a bit more than normal to allow for cooling.......................

a guy in my club has an OS 2 stroke 61 and it totally fits inside. The plane really moves with this engine.

I agree, I have this very setup with a pitts muffler (engine mounted sideways) and the plane fly's great.

I am using an O.S. .91FS with an optional 90 deg. elbow between muffler and engine. Muffler is hardly noticable as it now can be swiveled "mid-belly". Keeps the model clean too. Very little cutting to accomodate the engine head. Lots of cooling area available at the "cheeks". As others have said, " it's fast", very slippery. Landings give me fits sometimes as it doesn't want to stop flying unless I can put it into a pretty good headwind upon landing. Great airplane!!

I have seen 2 different shoestrings fly and both had a Saito 100,this was the perfect match.

I flew my String with a HB 61 and a Slimline Pitts Muffler. The only holes in cowl were for glow plug and an air outlet just behind the engine on the bottom of the right hand cheek cowl. Looked great and flew at scale speed. Looked just like the full size Shoestring at Reno Races Don't forget the full size plane only goes a little over 200 or so which at 1/4 scale is between 50 and 60 mph. Saw a plane with a 120 4 stroke and the cowl was butchered to get the engine in and he had to mount the tail servos on the outside of the fuse under the stab. It flies great with a 60 and balanced with no weight added. PS I see Great planes now has a Cosmic Wind to go along with the String and Little Toni!!

I decided that I didn't want to cut up the cowl on my shoe either, and after some research, found that a Tower .75 would just fit mounted horizontally without cutting the cowl. Am running a Bisson pitts style muffler which has a nice throaty sound, and gives good pressure to the tank. Only holes in the cowl are 2- 3/4" x 3-1/2" slots for the muffler which have not given any cooling problems so far. Have been very pleased with the Tower (my first one) and has been radared at 96 mph running an APC 12x8 with 15% nitro. I did some reinforcing mods to the fuse which made it come in at 8 lbs. Have about 40 flights on her and am very happy with the way it flies, on rails, but will do very nice axial rolls, inverted flight is very stable. If you want your plane to hold up, I would advise reading some of the threads on the SS which describe how to fix the belly area and landing gear plate which are the only weak areas on this ARF. I replaced the very flimsy 3/16 balsa stringers with 1/4 spruce stringers on just the underside, and reinforced the landing gear plate with triangle stock embedded in wet glass and cloth on both the upper and lower sides. Also reinforced the wheel pants with a couple layers of 2 oz. FG and made the plywood plates larger to spread the load out. This thing is bulletproof now and has come down hard a few times with no problems. One of the best, no, the best ARF of the 20 I have put together and flown. Just do the mods as described in the threads and you will be very pleased with this little gem.

I have a o.s. 91 fx in mine and it fit entirly inside the cowl i did have to make to cleance cuts in the lower portion for the bisson muffler im running. I also had to open up the right cowl cheeck for extra cooling of the engine but you really cant tell that i did it. I would definantly recomend this engine its wicked fast with a 13/7 apc prop and im still tunning the engine/prop combination. im also thinking of making hatches for the aileron servos to clean up the airframe even more.
I havent had her clocked yet but i guestimate around 100-110mph i only have 10 flights on her.