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I decided to go back to one of my favorite upscales today and see if I could tweak things a little bit to make it lighter. Originally I had used 2 mm depron wrapped around a 4-in mandrel in a double layer to make the body tube which worked and made a nice stiff tube, but it tended to flatten a bit over time since the 2mm was very stiff. On my later versions, I went to a BT 101 which was about an ounce heavier but didn't take as much work, both of those versions weighed in the 11 to 12 oz ready to fly range with an e6 motor and radio gear and used the older stiffer 6 mm depron with 1/8 inch spars for the flight surfaces. Eventually I converted all four of my previous versions to have electric motors mounted in the rocket motor mount and I fly them that way, one of my favorite planes I've designed.
This time I used the new 3 mm depron in a single layer, it's able to be pre curved by running it back and forth over a table edge with hand pressure several times to make a nice curve so it fit the mandrel well and didn't put much strain on the glue joint so I could use a single layer. I did reinforce the inside of the joint with a 2-in wide piece of curved 3 mm that I trimmed from the same 22" long sheet I used for the tube. This yielded a 4.25" tube and about 2.6x upscale.
Flight surfaces are the new 9mm depron with a single 2.5 mm spar in the vertical stab and two 2.5 mm spars top and bottom on the wing at about the 20% point, the spars top and bottom act like an I-beam once glued and taped in place and makes the wing very stiff. I used 6 mm depron for the trailing edge elevons.
The wing is moved forward compared to the original to move the flight CG forward a bit to help with lateral stability margin.
I used some nice photo paper for the cockpit upscaled from the original plans about 2X and hand cut some trim vinyl.
I added a double thick 9mm piece on the forward bottom of the tube to help give it some stiffness for landing and to simulate the original fuel pod that contained the clay weight.
The rail buttons and T-nuts are mounted inside the tube on the vertical stab tab which runs the full height of the body tube inside and are reinforced with some styrene plates so the rail goes right up the hollow center.
The motor tube/thrust line is offset slightly below center, the large wing has a lot of drag and isn't quite offset by the vertical stab, previous versions had the motor tube mounted at the bottom inside of the body tube but I always needed a little bit of down trim for boost so hopefully this will work a little bit better.
As before, I put the little T-tail on top of the stab instead of mounted on the leading edge of the stabilizer to reduce drag but keep the look of the original model.
Nothing is ejected from the model.
Right now the model weighs 9.5 Oz ready to fly which is a pretty significant reduction in weight hopefully the test flights go well tomorrow.
It's a little over 4.25 in. in diameter, 32-in. wingspan and 28 in. long.
This time I used the new 3 mm depron in a single layer, it's able to be pre curved by running it back and forth over a table edge with hand pressure several times to make a nice curve so it fit the mandrel well and didn't put much strain on the glue joint so I could use a single layer. I did reinforce the inside of the joint with a 2-in wide piece of curved 3 mm that I trimmed from the same 22" long sheet I used for the tube. This yielded a 4.25" tube and about 2.6x upscale.
Flight surfaces are the new 9mm depron with a single 2.5 mm spar in the vertical stab and two 2.5 mm spars top and bottom on the wing at about the 20% point, the spars top and bottom act like an I-beam once glued and taped in place and makes the wing very stiff. I used 6 mm depron for the trailing edge elevons.
The wing is moved forward compared to the original to move the flight CG forward a bit to help with lateral stability margin.
I used some nice photo paper for the cockpit upscaled from the original plans about 2X and hand cut some trim vinyl.
I added a double thick 9mm piece on the forward bottom of the tube to help give it some stiffness for landing and to simulate the original fuel pod that contained the clay weight.
The rail buttons and T-nuts are mounted inside the tube on the vertical stab tab which runs the full height of the body tube inside and are reinforced with some styrene plates so the rail goes right up the hollow center.
The motor tube/thrust line is offset slightly below center, the large wing has a lot of drag and isn't quite offset by the vertical stab, previous versions had the motor tube mounted at the bottom inside of the body tube but I always needed a little bit of down trim for boost so hopefully this will work a little bit better.
As before, I put the little T-tail on top of the stab instead of mounted on the leading edge of the stabilizer to reduce drag but keep the look of the original model.
Nothing is ejected from the model.
Right now the model weighs 9.5 Oz ready to fly which is a pretty significant reduction in weight hopefully the test flights go well tomorrow.
It's a little over 4.25 in. in diameter, 32-in. wingspan and 28 in. long.
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