First Flight A-Corn

The Rocketry Forum

Help Support The Rocketry Forum:

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
Back on the old TRF, I was in the middle of a build thread on the A-Corn from First Flight Hobbies. Then things went kaput.:(

I have since completed the rocket, given it a single test flight and through the magic of SECRET FORMULA X86, can recreate the build thread word for word.

As you may know, the A-Corn is the 13mm version of the 18mm Corn Roc.


Here Goes:

Construction is very similar to that of the Corn Roc. It begins with making a slit in the motor tube for the engine hook. The hook is then placed and held down with tape. A thrust ring is inserted in the forward end and glued into place. Finally, the centering rings are slipped on and glued. I found the centering rings to be very tight and the hole was too small to allow my finger access with sandpaper. I finally filed away some of the thickness with a rat tailed file.

AC-mm-1.jpg


AC-mm-2.jpg


AC-mm-3.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The fins are cut from sheet stock using a paper template printed in the directions. I cut the template out and traced the pattern onto the balsa. I then used an X-acto to cut the fins out. I made no effort to keep them all the exactly the same figuring that minor differences would add to the character of the rocket.

AC-fins-1.jpg


AC-fins-2.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The instructions recommend that the fins be left their natural balsa coloring to better blend with the look of this rocket. I liked the effect with the Corn Roc so decided to do the same with the A-Corn. The instructions also recommended that the fins be sealed with a clear coat to better protect them and to prevent warpage. I used 3 coats of Rustoleum Crystal Clear on each side.

AC-fins-3.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The recovery harness is based upon a thread of Kevlar tied around the motor mount. I tied the Kevlar in place and sealed it with a glue fillet. I also cut a small notch to accomodate the passage of the Kevlar.

AC-mm-4.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
After a long hiatus, the motor mount was inserted into the BT and held in place with yellow glue.

AC-mm-5.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
I gave the glue on the motor mount/ BT junction some time to dry and then inserted the BT into the styrofoam ear of corn and placed it with 5 min epoxy.

AC-BT-installed-1.jpg


AC-BT-installed-2.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The lines for the fin mounting are pre-marked on the corn. They are significantly short of the true length of the root edge but are easily lengthened.

I used an X-acto to cut a pair of parallel lines the width of the fin and then used the blade to gouge out the material. When done, the fin slid easily into place. I removed it and filled the trough with epoxy then re-inserted the fin.

AC-fins-mounted-1.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The other 3 fins were mounted likewise.

AC-fins-mounted-2.jpg


AC-fins-mounted-3.jpg


AC-fins-mounted-4.jpg


AC-fins-mounted-5.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The nose cone is simply the front end of the stryrofoam corn. To keep it in place on the rocket, a balsa coupling tube is attached to the NC which will fit into the BT. Mine needed a good deal of sanding to fit properly. It was affixed with 5 min. epoxy.

AC-NC-1.jpg


AC-NC-2.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
When the epoxy had set, the eyescrew was threaded into the balsa and backed out. The threads were dipped into yellow glue and the screw re-inserted.

To provide nose weight, BBs were wedged int othe space between the balsa and the foam. A coating of yellow glue was then applied to keep the BBs in place and to serve as an ablative surface proctecting the foam from ejection gasses. Glue was also painted onto the opposing surface.

AC-NC-3.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The A-Corn came with an 8" Thermal Rider parachute from Hartle Engineering. As a general rule, I don't like plastic parachutes but, if I'm going to have one, this is the type to go with.

The chute went together easily and was connected to a provided snap swivel. The swivel was then connected to the NC.

AC-Chute-1.jpg


AC-Chute-2.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The final step in construction was the addition of the launch lug. I did not do this according to the instructions. The provided lug was supposed to be cut in half and then each half glued to one of the fins along an offset line provided on the template. I did this with my Corn Roc and it worked fine. This time, I just glued the in tact lug to the line with yellow glue.

AC-lug.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The installation of the launch lug completed construction. The A-Corn is now ready for its maiden flight.

AC-completed-1.jpg


AC-completed-2.jpg


AC-completed-3.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
The maiden flight of the A-Corn was on an Estes 1/2A3-2, the smallest of the recommended motors. There was no problem in preparation beyond the engine hook being a little bit tight. The rocket took off straight, flew well, but as expected, not too high. The 2 second delay is a bit long but the chute popped and it recovered safely. I was getting ready to try it on an A3-4 when I learned that the launch lug had popped and I would need to replace it before this one can fly again.

A video of the short flight can be seen here: https://flickr.com/photos/[email protected]/3203955067/in/set-72157612634957843/

AC-f1a.jpg


AC-f1b.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
When I got the rocket back to the shop, I could see the spot where the lug popped. I figure the torque from being so far from the centerline was one contributor and gluing to the clear coat was another.

popped-lug.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
I decided to put the lug on the right way this time and sliced an 1/8" lug in half. This should reduce some of the torque while the rocket is on the rod.

lug-1.jpg


lug-2.jpg
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
A file was used to remove the clear coat where the new lugs would be attached and then the two lugs were put on a piece of rod and glued into place with yellow glue.

It's ready to fly again!

glued-lug.jpg
 

rstaff3

Oddroc-eteer
Joined
Jan 18, 2009
Messages
11,763
Reaction score
22
Great photo documentation, as usual! Still haven't flown mine :(
 

Fred22

Well-Known Member
Joined
Jan 6, 2009
Messages
2,460
Reaction score
4
Great thread. Got me wonderring about a potato being of Irish ancestry :)
Cheers
fred
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
Great photo documentation, as usual! Still haven't flown mine :(
I had a long building dry spell as I had things to do for the church and then an even greater flying dry spell. My last club launch was called due to winds. I got tired of waiting for a prospective bride and groom to show up yesterday and decided to amuse myself as I waited.

I'm looking forward to trying it on the larger power and also building the E version.
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
Great thread. Got me wonderring about a potato being of Irish ancestry :)
Cheers
fred

Interesting question.

Next time I get up to the great frozen north we need to discuss the issue over a few pints of Guinness!
 

Fred22

Well-Known Member
Joined
Jan 6, 2009
Messages
2,460
Reaction score
4
Interesting question.

Next time I get up to the great frozen north we need to discuss the issue over a few pints of Guinness!
It would be a pleasure sir :) The next time I head to Texas perhaps we could discuss it over some of that famous texas BBQ. Man you folks do that up well. My parents are at present winterring over in your fine state :)
Cheers
fred
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
It would be a pleasure sir :) The next time I head to Texas perhaps we could discuss it over some of that famous texas BBQ. Man you folks do that up well. My parents are at present winterring over in your fine state :)
Cheers
fred
BBQ and Guinness...I reckon that's doable. I might even get a head start so better hurry up!
 

CharlaineC

Well-Known Member
Joined
Jan 19, 2009
Messages
1,099
Reaction score
4
i have built the full family and really enjoied the builds built them in two days. the e was slighly tricky because she was extreamly tail heavy. so i hollowed out the balsa nose insert inorder to hold the bb's better. she took more then was included but i always have more. havent flown her yet but she swing tested great. needs a min of a 6' rod though.

cutting the slots for the fins i used a dreamel did a great job. make sure you use a steel streaght edge.

also use a launch lug that is the full size of the stuffer tube and use expanding foam to fill the gaps in the body of the corn E. works great.
 

Fred22

Well-Known Member
Joined
Jan 6, 2009
Messages
2,460
Reaction score
4
i have built the full family and really enjoied the builds built them in two days. the e was slighly tricky because she was extreamly tail heavy. so i hollowed out the balsa nose insert inorder to hold the bb's better. she took more then was included but i always have more. havent flown her yet but she swing tested great. needs a min of a 6' rod though.

cutting the slots for the fins i used a dreamel did a great job. make sure you use a steel streaght edge.

also use a launch lug that is the full size of the stuffer tube and use expanding foam to fill the gaps in the body of the corn E. works great.
Good to see you back Charlaine :)
Cheers
fred
 

Peartree

Cyborg Rocketeer
Staff member
Administrator
Global Mod
Joined
Jan 6, 2009
Messages
5,710
Reaction score
1,174
Location
Alliance, Ohio
Hi Charlaine! Good to see you back. How's every little thing?
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
i have built the full family and really enjoied the builds built them in two days. the e was slighly tricky because she was extreamly tail heavy. so i hollowed out the balsa nose insert inorder to hold the bb's better. she took more then was included but i always have more. havent flown her yet but she swing tested great. needs a min of a 6' rod though.

cutting the slots for the fins i used a dreamel did a great job. make sure you use a steel streaght edge.

also use a launch lug that is the full size of the stuffer tube and use expanding foam to fill the gaps in the body of the corn E. works great.
Thanks for the feedback but can you expand on what you meant by a "lug the size of the stuffer tube" for me?
 

CharlaineC

Well-Known Member
Joined
Jan 19, 2009
Messages
1,099
Reaction score
4
ok well the body tube in the case of the corn rocs is honestly a stuffer tube in other words its where the recovery and wadding goes. the launch lug for the corn-E should be as long as the tube.


as for me i'm doing ok i guess been dealing with alot still walking (thank god) and health is ok
 

JAL3

Well-Known Member
Joined
Jan 18, 2009
Messages
13,436
Reaction score
96
ok well the body tube in the case of the corn rocs is honestly a stuffer tube in other words its where the recovery and wadding goes. the launch lug for the corn-E should be as long as the tube.


as for me i'm doing ok i guess been dealing with alot still walking (thank god) and health is ok
Thanks for the clarification. I still haven't opened mine yet and what you described is different from the smaller two.

Its good to hear things are going well for you, even if busy. I remember the thread on the old TRF where you described starting to walk again. Good Stuff!
 
Top