First Flight Corn E

[JAL3]

I mixed a bit of 5 minute epoxy, the last I had, and coated the end of a fine along the root edge. I also put some along the foam on the newly cut angle to adhere to the fin. The fin was then put into the slot and pressed against the angled side.

 

[JAL3]

I took what was left of the epoxy and coated both sides of the foam wedge I had removed. The wedge was then tamped down into the gap between the exposed fin edge and the old, straight groove wall. I did not perfectly conceal the blunder but it helped a lot.

 

[JAL3]

For the second fin, I just rotated the rocket 90 degrees and eyeballed the approximate alignment. I marked the front and back of the fin location as if it were going on straight and then marked off 1/4" to the side at the bottom. A diagonal line was then drawn between the top and the bottom offset.

 

[JAL3]

A trough for the fin was then excavated and filled with a generous portion of Titebond II. The fin was placed and it was set aside to set up a bit.

 

[JAL3]

While the second fin was setting up, I took out the balsa coupler used to join the BT and the NC and test fitted it into the body. It was a bit tight so I gave it some sanding until it fit well.

 

[JAL3]

The coupler was then tested in the NC and found to fit fine.

 

[JAL3]

The coupler was removed and I then excavated some foam from behind where the coupler seats to accommodate some BBs for noseweight. The BBs were provided with the kit.

 

[JAL3]

The BBs were then drowned in a puddle of Titebond and the balsa coupler was inserted.

 

[JAL3]

The previously described procedure for mounting the fins, having worked, the remaining two were mounted likewise.

 

[JAL3]

With the fins in place, the body was set aside to dry.

 

[rstaff3]

After the trench was already cut, I remembered something that I wished I had remembered before cutting. First Flight has said that this rocket sometimes has problems with motors bigger than D12 due to the sloped nose. The shape causes to rocket not to fly straight. I remembered being told of a fix for this and contacted First Flight to find out what it was.

I'm not sure I buy that, unless the bigger motor was an E9...and then it's more likely and thrust/weight/drag issue. Also, will the canted fins really add enough spin to stabilize it? I don't know. The issues seen shouldn't be due to the overall profile as much as irregularities in its profile, the motor tube being not perfectly in the center, the fins not being on perfectly straight etc. I'd build mine with a straight set of fins and go for that 29mm mount (unless its a beta test build.)

 

[JAL3]

I'm not sure I buy that, unless the bigger motor was an E9...and then it's more likely and thrust/weight/drag issue. Also, will the canted fins really add enough spin to stabilize it? I don't know. The issues seen shouldn't be due to the overall profile as much as irregularities in its profile, the motor tube being not perfectly in the center, the fins not being on perfectly straight etc. I'd build mine with a straight set of fins and go for that 29mm mount (unless its a beta test build.)

The best I remember, the issues started above the E9. Any of the high thrust ones. I dunno. I can say that the cone has quite a slope to it on one side.

At this point, the deed is done. More importantly, I can say there is a reason besides poor craftsmanship that my rocket is spinning instead of flying straight.

 

[First_Flight]

I'm not sure I buy that, unless the bigger motor was an E9...and then it's more likely and thrust/weight/drag issue. Also, will the canted fins really add enough spin to stabilize it? I don't know.

Yes, it will even with the E9. It's not the best, but it works.

The issues seen shouldn't be due to the overall profile as much as irregularities in its profile, the motor tube being not perfectly in the center, the fins not being on perfectly straight etc.

Trust me. I tried several flights with D12-3 and E9. D12 boosts were quick and deployed at low altitude. E9 flights were shaped like rainbows with the deployment occurring back at ground level (ugly, to say the least). The nose cone is severely sloped on one side. The flight tended to arc away from the sloped side.

I'd build mine with a straight set of fins and go for that 29mm mount (unless its a beta test build.)

Charlaine did one with the 24mm mount and canted fins and has had a few good straight, though spinning, flights. It could benefit from more power, for sure, but I think an E9 motor will work as long as it spins a bit.

The purchasers were all warned about this tendency and the spin fix. If anyone who bought one has second thoughts and would like a refund please contact me.

The new ones will have larger interior tubes which will mean the bored hole is larger and there will be less foam which means lighter weight. It may also use a cluster mount for 2x or 3x D12 power. One thing for sure, it will DEFINITELY have multiple successful test flights before sales begin. Stay tuned.

 

[rstaff3]

Yes, it will even with the E9. It's not the best, but it works.



Trust me. I tried several flights with D12-3 and E9. D12 boosts were quick and deployed at low altitude. E9 flights were shaped like rainbows with the deployment occurring back at ground level (ugly, to say the least). The nose cone is severely sloped on one side. The flight tended to arc away from the sloped side.

Which is what I thought. The misshaped (purposely) body is the cause v. the overall profile. Also sounds underpowered on the E9. Most any 24mm reload should be a recommended motor.

Charlaine did one with the 24mm mount and canted fins and has had a few good straight, though spinning, flights. It could benefit from more power, for sure, but I think an E9 motor will work as long as it spins a bit.

Cool. I guess even a slow spin would help to even out the effects of the angled nose.

 

[JAL3]

A day later, the fins seemed pretty sturdy but I decided to fillet them anyway. This had nothing to do with a desire to increase aerodynamic efficiency. I just wanted to smooth things out a bit and add some strength. I used Titebond Trim and molding glue.

 

[JAL3]

I located the eyescrew for the nose and used it to pre-drill a hole in the balsa nose coupler.

 

[JAL3]

The hole was then flooded with Titebond II and the eyescrew was rethreaded into the hole.

 

[JAL3]

I still had some BBs left and wanted to make sure to use them since I am going to eventually push the power limits in this rocket. I poked them into the cavity along side the balsa coupler and then flooded them with more glue. This should also help strengthen the cone.

 

[JAL3]

The kit came with some strips of cornhusk to dress the project up as needed. I used them to fill out the tail end where the motor sticks out. The strips were dipped into glue and then tucked in. Care must be taken to keep them out of the exhaust path.

 

[JAL3]

The shock cord was tied to the nose and then a swivel was attached to the cord a few inches below the nose.

 

[JAL3]

The recovery harness was stuffed back into the tube and the nose put in place. With that, the Corn E is ready for the Cornfield Classic tomorrow morning.

 

[Green Arrow]

Looks interesting! ;o)

 

[JAL3]

Looks interesting! ;o)

The smaller versions have been fun.

Tomorrow, this one gets shown off at a local AFJROTC rocket competition called the Cornfield Classic. My club is helping out and each of us are bringing some static displays and one demo flight. This one is mine.

 

[JAL3]

The Cornfield Classic was held at Medina Valley High School in Castroville, TX. It was hosted by the AFJROTC program and had teams from programs all over Texas competing in a variety of events. Most of them are similar to NAR contests but they are not exactly the same. My club, the Alamo Rocketeers traditionally helps them with safety and judging. Everyone from the club who shows up is also invited to do some sort of demo flight, usually emphasize some area of rocketry the kids are unfamiliar with. This year, I just wanted to have fun and built my Corn E, nicknamed the Kornfield Klassic, because of the name of the event.

I expected everyone to appreciate my rocket but I was unprepared for the reception it got. Mine was the one that EVERYONE wanted to see fly.

As the contests wound down, my club members set up our demo rockets and waited for our turn.

 

[JAL3]

By popular demand, mine was up first. It took off majestically, as majestically as an ear of corn can, on an E9-4.

 

[JAL3]

It continued to rise fairly slowly and at first I wondered if it was going to spin at all. Perhaps I had not given enough angle to the fins.

 

[JAL3]

Then it started slowly to spin, picking up angular velocity as it went along. It definitely helped to average out the thrust direction as "down".

 

[JAL3]

When the fuel was spent it continued up for a little bit but quick started to arc over.

 

[JAL3]

It ejected right after apogee and it was nice to see that reassuring blob of orange chute in the sky.

 

[JAL3]

It drifted down at what seemed to be a safe rate. That was some concern because I replaced the provided 24" chute with a 15" nylon one.