BUSA STINGray 40 and 120
11-19-2004, 08:14 PM
#2
RE: BUSA STINGray 40 and 120
A few people built Stingrays as our club project a couple of years ago. The idea was to teach building skills to people who had soloed on an ARF trainer and they would have a good second plane to advance on. I led the project and although few took part, everyone who did was extremely happy with the way it flew, including at least one very experienced pilot who took out the dihedral, clipped the wings, and really made it go with an Irvine .53.
I loved mine, but it flew away after about a dozen flights. I think it was a receiver failure, but I'll never know for sure. It was very easy to fly, very smooth and predictable, and also very capable. It has a thick symmetrical airfoil and flies inverted very easily. I scratched out a stick built stab and fin, tapered the control surfaces and used a light OS 40 FP and it flew beautifully on that engine. Others built heavier and used the OS 46 FX and are very happy with theirs too.
Compared to the Sig Four Star, the airfoil is thicker and fully symmetrical instead of semi-symmetrical. It weighs about the same, which surprised me because the wing construction looks much heavier--certainly the wing is much stronger and more rigid and you can use any covering material, unlike the Four Star which relies on the covering for rigidity.
Many substituted dural gear which is probably a good ideal if you put on a ball bearing 46 and build on the heavy side. Mine, at 4 lbs 5 oz, did very well with the stock wire gear. Others came out around 5 lbs I think.
I did no beefing up except to tie the wing hold-down blocks together with a bit of ply (which means you can't use the aileron torque rods--I used two mini servos in the wing), and to use a little triange stock around the blocks and the landing gear area. It was very strong. The LG did tend to get bent back a bit, but it was easy to bend it forward again.
It is an old fashioned kit, the parts fit is not always so good and the instructions are not very complete. For those reasons it was an excellent teaching project. If you have some kit experience (other than laser-cut types) you will figure it out pretty quickly and easily. The end result is about perfect as a step up from a trainer, especially if you don't weigh it down. I've been thinking about doing it again light with a TT .36, which is the same weight as the 40 FP, but more powerful. But everyone else used bigger engines. Jim
I loved mine, but it flew away after about a dozen flights. I think it was a receiver failure, but I'll never know for sure. It was very easy to fly, very smooth and predictable, and also very capable. It has a thick symmetrical airfoil and flies inverted very easily. I scratched out a stick built stab and fin, tapered the control surfaces and used a light OS 40 FP and it flew beautifully on that engine. Others built heavier and used the OS 46 FX and are very happy with theirs too.
Compared to the Sig Four Star, the airfoil is thicker and fully symmetrical instead of semi-symmetrical. It weighs about the same, which surprised me because the wing construction looks much heavier--certainly the wing is much stronger and more rigid and you can use any covering material, unlike the Four Star which relies on the covering for rigidity.
Many substituted dural gear which is probably a good ideal if you put on a ball bearing 46 and build on the heavy side. Mine, at 4 lbs 5 oz, did very well with the stock wire gear. Others came out around 5 lbs I think.
I did no beefing up except to tie the wing hold-down blocks together with a bit of ply (which means you can't use the aileron torque rods--I used two mini servos in the wing), and to use a little triange stock around the blocks and the landing gear area. It was very strong. The LG did tend to get bent back a bit, but it was easy to bend it forward again.
It is an old fashioned kit, the parts fit is not always so good and the instructions are not very complete. For those reasons it was an excellent teaching project. If you have some kit experience (other than laser-cut types) you will figure it out pretty quickly and easily. The end result is about perfect as a step up from a trainer, especially if you don't weigh it down. I've been thinking about doing it again light with a TT .36, which is the same weight as the 40 FP, but more powerful. But everyone else used bigger engines. Jim
11-19-2004, 09:08 PM
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RE: BUSA STINGray 40 and 120
I did the 120 several years ago. About the most layed-back fun to fly plane I have had. Will fly amazingly tight manuevers for such a large aircraft. I flew it for quite a while with an old Fox .74, then installed a OS 1.20 4 stroke. It was a fun plane, until the crystal fell out of the receiver in a very low altitude (less than 3') high banked turn. Debris field must have been a 100 yards long.
There was a lot of balsa in that plane.[X(]
There was a lot of balsa in that plane.[X(]
11-20-2004, 02:21 PM
#5
RE: BUSA STINGray 40 and 120
I used an old one from a buddy for an engine test plane for a few years. Like the 4-Star, it needs a rib removed from each side. Rolls a lot better with the shorter span.
In addition, it does not need the dihedral. It rolls in knife edge so the wing should be built flat.
The wire gear worked fine for me.
In addition, it does not need the dihedral. It rolls in knife edge so the wing should be built flat.
The wire gear worked fine for me.
11-21-2004, 02:53 PM
#7
RE: BUSA STINGray 40 and 120
Whatever the dihedral is, it is too much. A buddy built it stock before I got the plane and it wallowed around rolls and wouldn't knife edge without rolling out.
Really, is isn't much more than a dressed up trainer with a semi symmetrical airfoil that has a turthedeck to make it look mid wing. If you are a pretty good flier, you will get tired of it in a hurry unless you make some improvements during construction.
The wings have plenty of area, but they are too long for good rolls given the fuselage length. They need to be shortened just like the 4-Star wings do.
Dihedral, wing vertical location and sweep combine to cause roll with rudder. A mid-wing plane should never need dihedral except to cancel a lot of forward sweep. This is if you want to fly knife edge and point rolls without compensating with opposite aileron or programming in mix.
Really, is isn't much more than a dressed up trainer with a semi symmetrical airfoil that has a turthedeck to make it look mid wing. If you are a pretty good flier, you will get tired of it in a hurry unless you make some improvements during construction.
The wings have plenty of area, but they are too long for good rolls given the fuselage length. They need to be shortened just like the 4-Star wings do.
Dihedral, wing vertical location and sweep combine to cause roll with rudder. A mid-wing plane should never need dihedral except to cancel a lot of forward sweep. This is if you want to fly knife edge and point rolls without compensating with opposite aileron or programming in mix.
11-21-2004, 08:53 PM
#8
RE: BUSA STINGray 40 and 120
It only calls for an inch of dihedral, and I agree with taking it out. Construction is a little simpler if you do, and I guess rolls will improve, though "wallow" seems a little harsh--but then my standards are certainly not those of an aerobatics columnist! If you're into knife edge then try tip plates that stick down but not up--that should reduce or eliminate the tendency to roll with rudder. Most people just left off the tip plates that come with the kit--they are too small to do anything anyway.
One small correction to the previous post--the airfoil is fully symmetric, not semi.
Jim
One small correction to the previous post--the airfoil is fully symmetric, not semi.
Jim
01-06-2005, 11:31 PM
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RE: BUSA STINGray 40 and 120
I had the 120 powered with an ASP 1.08. I had mounted the servos in the tail and ended up needing nose weight to balance it. Go figure. Oh well, it was also cloth covered and painted, so I'm sure that didn't help either.
Anyways, I agree with Ed on the dihedral - it doesn't need it. It also wouldn't hurt to cut a rib from each wing. Mine was built stock except for reduced dihedral and it flew pretty much like a 4 Star - (that s a compliment as far as I'm concerned, btw!) except I found the roll rate someone disappointing which I'm sure would have been greatly improved with a shorter wingspan. I do dissagree with the wire gear and skid tho. An appropriate sized Sullivan tailwheel assembly is a must for the back end and if you can get ahold of a dural landing gear blank for a Fourstar 120 go for it. I found the wire gear okay flying off pavement but very draggy in grass.
Anyways, I agree with Ed on the dihedral - it doesn't need it. It also wouldn't hurt to cut a rib from each wing. Mine was built stock except for reduced dihedral and it flew pretty much like a 4 Star - (that s a compliment as far as I'm concerned, btw!) except I found the roll rate someone disappointing which I'm sure would have been greatly improved with a shorter wingspan. I do dissagree with the wire gear and skid tho. An appropriate sized Sullivan tailwheel assembly is a must for the back end and if you can get ahold of a dural landing gear blank for a Fourstar 120 go for it. I found the wire gear okay flying off pavement but very draggy in grass.
