What size engine should I use?
02-19-2016, 08:19 AM
#1
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What size engine should I use?
I have an old Ugly Stik that I bought from a guy who built it over ten years ago. It had been sitting in his son's barn since then. It had never flown even though it had all the servos, receiver, and battery installed.
I replaced the receiver with a new Spektrum and replaced the battery with a new NiMh. Everything is mounted about as far forward as possible.
The wing span is 60". I had intended to use an OS 46AX engine, but once I mounted the engine, as far forward as possible, the plane was very tail heavy (I set the CG at 3-3/4" from the LE as per instructions on the new Great Planes 40-size stik). I assume that plane is similar to mine.
The thing needed 12 ounces of lead in the nose to balance. That makes it weigh 8-1/4 pounds.
So, will the OS 46AX be strong enough to fly this thing?
Or, should I try my TSI 75 engine instead?
Jack
I replaced the receiver with a new Spektrum and replaced the battery with a new NiMh. Everything is mounted about as far forward as possible.
The wing span is 60". I had intended to use an OS 46AX engine, but once I mounted the engine, as far forward as possible, the plane was very tail heavy (I set the CG at 3-3/4" from the LE as per instructions on the new Great Planes 40-size stik). I assume that plane is similar to mine.
The thing needed 12 ounces of lead in the nose to balance. That makes it weigh 8-1/4 pounds.
So, will the OS 46AX be strong enough to fly this thing?
Or, should I try my TSI 75 engine instead?
Jack
Last edited by Jack_K; 02-19-2016 at 10:28 AM.
02-19-2016, 09:15 AM
#3
Something doesn't add up - those airplanes normally need a light engine or equipment shifted aft to achieve proper CG. Was the nose shortened? If not, carefully inspect the tail of the airplane for something out of the ordinary or heavy; perhaps another flight pack battery is wedged in aft end of the fuselage. Based on wingspan, Great Planes manual for the Big Stik .40 shows CG range of 3.25 to 4.00 inches.
Last edited by H5606; 02-19-2016 at 09:19 AM.
02-19-2016, 09:18 AM
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Something doesn't add up - those airplanes normally need a light engine or equipment shifted aft to achieve proper CG. Was the nose shortened? If not, carefully inspect the tail of the airplane for something out of the ordinary or heavy; perhaps another flight pack battery is wedged in aft end of the fuselage.
02-19-2016, 09:28 AM
#5
Early Jensen Ugly Stick kits had a solid 5/16" stab. Later versions had a built up stab with 1/16" sheet top and bottom, and ribs in between. A gentle squeeze should reveal if you have the heavy stab.
Question: was it painted, or covered with film? It's possible that the builder "over did it" with glass, resin, and paint?
Question: was it painted, or covered with film? It's possible that the builder "over did it" with glass, resin, and paint?
02-19-2016, 09:38 AM
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Early Jensen Ugly Stick kits had a solid 5/16" stab. Later versions had a built up stab with 1/16" sheet top and bottom, and ribs in between. A gentle squeeze should reveal if you have the heavy stab.
Question: was it painted, or covered with film? It's possible that the builder "over did it" with glass, resin, and paint?
Question: was it painted, or covered with film? It's possible that the builder "over did it" with glass, resin, and paint?
I just measured the wing it's closer to 60 -61", not 58-1/2"
Last edited by Jack_K; 02-19-2016 at 10:27 AM.
02-19-2016, 10:41 AM
#7
Talking about unnecessary weight in the tail; just thought I'd include this experience from the past sort of like when one "can't see the forest for the trees". A new modeler showed up at the club field with a trainer he may have built and upon closer inspection, I discovered the balsa pushrods were wrapped at each end with heavy duty, solder because he didn't have any thread handy...
You could consider removing covering from tail surfaces, cutting lightening holes, recovering or removing and replacing with lighter built-up tail.
You could consider removing covering from tail surfaces, cutting lightening holes, recovering or removing and replacing with lighter built-up tail.
02-19-2016, 11:22 AM
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Talking about unnecessary weight in the tail; just thought I'd include this experience from the past sort of like when one "can't see the forest for the trees". A new modeler showed up at the club field with a trainer he may have built and upon closer inspection, I discovered the balsa pushrods were wrapped at each end with heavy duty, solder because he didn't have any thread handy...
You could consider removing covering from tail surfaces, cutting lightening holes, recovering or removing and replacing with lighter built-up tail.
You could consider removing covering from tail surfaces, cutting lightening holes, recovering or removing and replacing with lighter built-up tail.
02-19-2016, 03:15 PM
#11
The question of CG location has come up before. I believe it's been covered in the Kit Building Thread. About 4 5/8" back from the leading edge. That seems a little far back, for a 10" cord, which is the width of the basic wing. Adding the ailerons in to the cord makes that CG location more logical.
02-19-2016, 05:04 PM
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The question of CG location has come up before. I believe it's been covered in the Kit Building Thread. About 4 5/8" back from the leading edge. That seems a little far back, for a 10" cord, which is the width of the basic wing. Adding the ailerons in to the cord makes that CG location more logical.
02-19-2016, 07:34 PM
#13
My first Ugly Stick had a 60" wing span and was powered by a Webra .61. This was around the late 80s. Back then a 60" wing span generally meant .60 size airplane.
I would recommend a OS .65AX for your Ugly Stick.
Any pictures of this plane?
I would recommend a OS .65AX for your Ugly Stick.
Any pictures of this plane?
02-19-2016, 08:30 PM
#14
No matter how you cut it, a 60" stick that weighs 8 pounds is a flying cinder block. Strip the covering off the plane and find a way to get it closer to 6 pounds ready to fly. You will have a vary enjoyable plane.
Scott
Scott
02-19-2016, 09:17 PM
#15
My Feedback: (1)
Jack, With a 13 3/4" wing cord (MAC) the C/G range of 25%-33%, is 3.43"- 4.53". Right in the middle @ 29% is 3.98". This in not a 40 size G.P. Stick. The wingspan is not a factor in the C/G setting but the cord size IS. All in all you must have a stick intended for more engine than a 46. Go bigger and balance somewhere in the 29 or 30% of the MAC area.
02-19-2016, 10:23 PM
#16
The Pamster. Was your Webra a Black Head, or the Webra Speed? Most of my dozen or so were flown with the Black Head. My first Ugly Stick was in the late 60's (silk and dope). I've had one almost continuously since then. Fly off land, water, and snow. Not any snow since I've been in Tennessee. The only Ugly Stick I ever flew that was close to 8 lb's was when I was carrying 37 oz. of fuel for a cross country flight. It flew, but was a little "doggy".
02-20-2016, 07:37 AM
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The Pamster. Was your Webra a Black Head, or the Webra Speed? Most of my dozen or so were flown with the Black Head. My first Ugly Stick was in the late 60's (silk and dope). I've had one almost continuously since then. Fly off land, water, and snow. Not any snow since I've been in Tennessee. The only Ugly Stick I ever flew that was close to 8 lb's was when I was carrying 37 oz. of fuel for a cross country flight. It flew, but was a little "doggy".
Jack
02-20-2016, 10:14 AM
#18
The Pamster. Was your Webra a Black Head, or the Webra Speed? Most of my dozen or so were flown with the Black Head. My first Ugly Stick was in the late 60's (silk and dope). I've had one almost continuously since then. Fly off land, water, and snow. Not any snow since I've been in Tennessee. The only Ugly Stick I ever flew that was close to 8 lb's was when I was carrying 37 oz. of fuel for a cross country flight. It flew, but was a little "doggy".
What's an extra pound or two? Ballast, that's what. Lol.
03-13-2016, 01:43 PM
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There's a solid bulkhead blocking sight into the rear of the fuselage. But, after closer inspection, it seems the entire fuselage is made of 1/4" extra hard balsa or perhaps even plywood. Tapping on the top, bottom, or sides sounds like good solid wood. That makes me think it's plywood.
The area of the fuselage where the wing opening is certainly looks and feels like plywood. It's been painted, but feels rough to the touch. That's why the plane is so heavy is my guess. So, I'd like to drill or cut some lightening holes in the rear portion of the fuselage. Maybe in the horizontal stab, too, since it's also solid and hard.
Anyone have any suggestions on how I can accomplish that?
Jack
The area of the fuselage where the wing opening is certainly looks and feels like plywood. It's been painted, but feels rough to the touch. That's why the plane is so heavy is my guess. So, I'd like to drill or cut some lightening holes in the rear portion of the fuselage. Maybe in the horizontal stab, too, since it's also solid and hard.
Anyone have any suggestions on how I can accomplish that?
Jack
03-14-2016, 11:12 AM
#22
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As already suggested, drilling holes does pretty good. Of course, the sharper your bits the better. Brad point bits will probably be the type that cuts the cleanest holes the size you need. You'll really only need a couple of sizes.
Removing wood from your elevator is the top priority, with the stabilizer second.
Stripping the covering is the first step. Getting clean holes isn't a big deal unless you recover with transparent film. If it matters, roll up some sandpaper and make each hole perfect.
I'd hazard a guess no holes would be needed forward the wing TE if balance is the only goal.
Removing wood from your elevator is the top priority, with the stabilizer second.
Stripping the covering is the first step. Getting clean holes isn't a big deal unless you recover with transparent film. If it matters, roll up some sandpaper and make each hole perfect.
I'd hazard a guess no holes would be needed forward the wing TE if balance is the only goal.
03-14-2016, 01:40 PM
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As already suggested, drilling holes does pretty good. Of course, the sharper your bits the better. Brad point bits will probably be the type that cuts the cleanest holes the size you need. You'll really only need a couple of sizes.
Removing wood from your elevator is the top priority, with the stabilizer second.
Stripping the covering is the first step. Getting clean holes isn't a big deal unless you recover with transparent film. If it matters, roll up some sandpaper and make each hole perfect.
I'd hazard a guess no holes would be needed forward the wing TE if balance is the only goal.
Removing wood from your elevator is the top priority, with the stabilizer second.
Stripping the covering is the first step. Getting clean holes isn't a big deal unless you recover with transparent film. If it matters, roll up some sandpaper and make each hole perfect.
I'd hazard a guess no holes would be needed forward the wing TE if balance is the only goal.
I measured the horizontal stab and found it's 5/16" thick. The elevator is 1/4". I guess I now need to buy some 3/16" balsa, print out the plans, and get to work.
03-14-2016, 01:55 PM
#24
Senior Member
I went ahead and cut some holes in the side --- 2'", 1-1/2", and 1" progressively. In the process I buggered up one of the control rods, so that's something else to fix.
I measured the horizontal stab and found it's 5/16" thick. The elevator is 1/4". I guess I now need to buy some 3/16" balsa, print out the plans, and get to work.
I measured the horizontal stab and found it's 5/16" thick. The elevator is 1/4". I guess I now need to buy some 3/16" balsa, print out the plans, and get to work.
