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  #1  
Old 12-23-2008, 12:43 PM
Ntxrcrc Ntxrcrc is offline
Intermediate Rocketeer
 
Join Date: Aug 2008
Posts: 58
Default Scratch Build - Downscale SA-14 Archer

Built this one during the Thanksgiving holiday. Finally got a break in the weather to paint last weekend and just finished up the build last night.

First, big thanks to Jetlag for providing the critical dimensions from his own Archer!

A scale factor of .65 was used to match the diameter of BT80 body tube.

The design criteria was for a bird to fly in the contraints of the field I fly in, and to use 24mm BP motors. This required I build the rocket light. With this in mind, I used standard BT80 tube, balsa fins, presentation board CR's, and yellow glue for contruction.

Tubes and most parts are from Semroc. Plastic nose cone is from Apogee, it had the proper 4:1 ratio as the original Archer.

Propulsion is by a dual 24mm cluster mount to use D12's and E9's.

Using model rocket construction on a rocket of this size, I had to design it to be strong.
The motor mount tubes extend forward of the trailing edge of the strakes, three centering rings are used on the motor mount assembly, two to support the primary fins, and one to support the trailing edge of the strake fins.

A tube coupler with a built in ejection baffle was installed at the forward portion of the strake fins.

Once built, the airframe is very strong for the materials used.

1/4" launch lugs are used.

Recovery is by a 24" nylon chute, kevlar to elastic shock cord.

Finish is Rustolium grey automotive primer, with Rustolium gloss white top coat.

I deviated from the standard NCR SA-14 decals in favor of stripes loosely based on military markings from a Pheonix missile.
Monokote Trimkote was used for the stripes - excellent stuff for stripes!

Finished weight with recovery system is 11.2 oz.

Simulations estimate 561.7 ft altitude with 2 D12's, and 947.4 ft with 2 E9's.
Just right for my field size.

Now just to get the weather to cooperate for a launch!

I did not take any pictures during the build, as I was doing a lot of design on the fly. More of a prototype build, but I am pleased with the results.

Here is a few shots of the finished rocket.
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  #2  
Old 12-23-2008, 12:52 PM
jetlag jetlag is offline
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Join Date: Aug 2006
Posts: 2,279
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Quote:
Originally Posted by Ntxrcrc
Built this one during the Thanksgiving holiday. Finally got a break in the weather to paint last weekend and just finished up the build last night.

First, big thanks to Jetlag for providing the critical dimensions from his own Archer!

A scale factor of .65 was used to match the diameter of BT80 body tube.

The design criteria was for a bird to fly in the contraints of the field I fly in, and to use 24mm BP motors. This required I build the rocket light. With this in mind, I used standard BT80 tube, balsa fins, presentation board CR's, and yellow glue for contruction.

Tubes and most parts are from Semroc. Plastic nose cone is from Apogee, it had the proper 4:1 ratio as the original Archer.

Propulsion is by a dual 24mm cluster mount to use D12's and E9's.

Using model rocket construction on a rocket of this size, I had to design it to be strong.
The motor mount tubes extend forward of the trailing edge of the strakes, three centering rings are used on the motor mount assembly, two to support the primary fins, and one to support the trailing edge of the strake fins.

A tube coupler with a built in ejection baffle was installed at the forward portion of the strake fins.

Once built, the airframe is very strong for the materials used.

1/4" launch lugs are used.

Recovery is by a 24" nylon chute, kevlar to elastic shock cord.

Finish is Rustolium grey automotive primer, with Rustolium gloss white top coat.

I deviated from the standard NCR SA-14 decals in favor of stripes loosely based on military markings from a Pheonix missile.
Monokote Trimkote was used for the stripes - excellent stuff for stripes!

Finished weight with recovery system is 11.2 oz.

Simulations estimate 561.7 ft altitude with 2 D12's, and 947.4 ft with 2 E9's.
Just right for my field size.

Now just to get the weather to cooperate for a launch!

I did not take any pictures during the build, as I was doing a lot of design on the fly. More of a prototype build, but I am pleased with the results.

Here is a few shots of the finished rocket.


You did a BEAUTIFUL job! It looks fantastic! Can hardly wait for the flight pics!
Glad to help, anytime!
Gorgeous, really!
Allen M
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  #3  
Old 12-23-2008, 12:57 PM
Indiana Indiana is offline
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Join Date: May 2008
Posts: 148
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Very nice. Twin E9s should make for a great launch.
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  #4  
Old 12-23-2008, 07:48 PM
Ntxrcrc Ntxrcrc is offline
Intermediate Rocketeer
 
Join Date: Aug 2008
Posts: 58
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Yes, the E9's should be a good flight.

Matter of fact, just stocked up on E9's, Hobby Lobby has all rocketry items 30% off this week. Cleaned out my local store of their stock of E9-6's.
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  #5  
Old 06-22-2009, 08:03 PM
Ntxrcrc Ntxrcrc is offline
Intermediate Rocketeer
 
Join Date: Aug 2008
Posts: 58
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Between bad weather and burn bans, I finally got the chance to fly the downscale Archer six months after finishing it.

This past weekend the DARS club held their monthly launch, and luckily no burn ban.
Weather was clear and sunny, in the mid 90's, south wind 10 to 15mph and gusty.

Flight was excellent on 2 D12-5's. Left the pad with authority, straight as an arrow despite the strong south winds.

I had sim'd this rocket to about 560', it appeared to have reached this altitude. (no confirmation, but looked right) Deployment was just past apogee and under the chute flawlessly.

Long drift in the strong winds with landing just at the end of the field. (LONG walk!)

Recovering the Archer, everything looked fine, one fin dislodged slightly from the landing, but easily repairable.

Something didn't feel right when I picked it up, it felt too light!
The dual motor mount was missing, just plain gone. I did not see anything depart from the rocket during the flight????

On the walk back to the pads, I came across the missing motor mount half way between the pads and the landing site. (Pure luck!)
It appears my homemade presentation board centering rings were not up to the task and failed.

All in all though, a very successful flight. This rocket really flies great, looking forward to a 2x E9 flight. Fin is already repaired and I'm working on some new (and stronger) centering rings.

In my haste to get this bird in the air, I forgot to snap a few photos, bummer, it was a great flight. I'm hoping someone else at the DARS launch might have snapped a few.
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