Upscale Tornado

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aerostadt

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A few years ago a club member launched something like an upscale Tornado and I loved it. Unfortunately, I didn't get his name or any details of his rocket. Recently, I realized that it was based on the low-powered (LPR) Estes tornado. I found the Tornado RocSim model on Rocket Reviews and downloaded it and proceeded to upscale it by a scale factor of 3.48. I then proceeded to replace the parts in the RocSim model. I wanted to use parts from my inventory, so actually the model is not a true upscale. So, originally the airframe was a BT-20 and now it is a BT-80. However, the basic idea to use "maple seed" recovery for the upper part and flutter recovery for the lower part is preserved.

I plan to use 24 mm motors, so the fins will require through-the-wall tabs. The exterior shape of all 3 fins is the same (although different from the original Estes), but the tab will be different for the fin that goes in the maple seed upper section.
 

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aerostadt

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I made an internal 24 mm mounting tube that has a built-in fin slot that will hold the tab for the upper section fin. This fin mounting part will slide into the base of the "maple seed" upper section and will be able to capture the single upper fin.
 

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aerostadt

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The RocSim file for the original Estes Tornado can be found on Rocket Reviews. The fun thing about the RocSim model is that the upper Maple Seed section is modeled simply as a second stage with no sustainer motor in it. This way the viewer can see the Maple Seed section by itself or the whole model together.

 

aerostadt

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The lower section that contains the motor is a 5-inch length of BT-80 tube. I am using the coupler tube from Balsa Machining Service that fits in the BT-80 and also centering rings from BSM. I found that I could start construction by simply gluing a CR on the 24 mm tube. This CR is then glued on to the bottom of the coupler tube. I used a fin guide from Apogee for finding the fin locations.
 

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aerostadt

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I glued in the coupler tube with the 24 mm motor tube into the BT-80 airframe. I cut off about 1/4" of the 24 mm tube, so that I could glue on the rear motor retainer. This lower section is then slotted to receive the 2 large fins and the 2 smaller fins. The 2 smaller fins are attached close together and form a loose guide for the large fin from the upper section.
 

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aerostadt

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I have glued in all the fins into the lower section. I am thinking of putting in another CR in the lower section, but I am not sure. The dry fit of both sections is good.
 

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jqavins

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I wonder if the lower section could be trimmed to glide rather than tumble. There are reasons for a tail distinct from the wings, but there are also flying wings. It wouldn't be easy, I'm just wondering if it would be possible.
 

aerostadt

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I wonder if the lower section could be trimmed to glide rather than tumble. There are reasons for a tail distinct from the wings, but there are also flying wings. It wouldn't be easy, I'm just wondering if it would be possible.
Joe, I'm assuming that I have a tumbler for the bottom section. I haven't launched, yet, so I am hoping to find out. As you say it wouldn't be easy and at the least it would be a re-design. As I recall the old Centuri Black Widow, which I think used 18 mm motors, had huge fins on the first stage and did have glider recovery for the first stage.

Rocket Reviews describes the Black Widow here:
 
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BABAR

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Very nice!

I think you should be okay with basswood. Your fin grain direction may be suboptimal, particularly for the upper section that has limited surface area for tube fin joint.
 

aerostadt

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I launched the Tornado for the first time at the UROC meet last Saturday (03/27/2021) successfully on an F32-6. This was too much power for my likes. Take-off was very fast with some fish tailing during the initial boost. I need to use a smaller motor and not go so high. Rocksim predicted 1,487 feet for altitude and my eyeballs would agree. It was way up there. Actually, I lost sight of the maple seed upper section, although, I think I saw it initially going into the flat spin that it is suppose to do. The booster did tumble recovery. Spectators thought that it was a separation failure, because there is no parachutes with this model. I want to thank UROC members for pointing out to me where the model landed. Recovery was quick after some walking. There was no damage on either of the two parts.
 

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jqavins

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It went up and came down with no damage, ready to fly another day; that's a success. It did so in the manner intended; that's a big success. It fooled the spectators, made them think there was a failure when it was actually doing what it was supposed to; that's a triumph. ;)

For fishtailing, my off hand guess would be rod whip, but of course there is no shortage of other possible explanations. For lower altitude, I guess you'd be going to an E motor. Be sure to see what RockSim says about rod exit speed, as you may need a relatively high thrust E.
1617043103047.png
 

aerostadt

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It went up and came down with no damage, ready to fly another day; that's a success. It did so in the manner intended; that's a big success. It fooled the spectators, made them think there was a failure when it was actually doing what it was supposed to; that's a triumph. ;)

For fishtailing, my off hand guess would be rod whip, but of course there is no shortage of other possible explanations. For lower altitude, I guess you'd be going to an E motor. Be sure to see what RockSim says about rod exit speed, as you may need a relatively high thrust E.
View attachment 457480
Thanks, Joe, for the encouragement and the thrust-time curves. I will check out the E20 and the E30 in RockSim. I think have E20's in my inventory. There might have been a little bit of wind kicking up at the time of launch, so that might have contributed to the fish-tailing. This model has turned out lighter after construction than I thought it would be.
 

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