HIGHEST FLYING KIT USING 4" AIRFRAME AND DUAL DEPLOY

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neond7

neond7

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I'm involved in a rocketry contest at work - basically, the office in Maryland has challenged the Florida office to a max apogee contest.

• The rocket shall utilize a 4” airframe and may be a commercially available kit or scratch built design.
• The rocket shall use a designated commercially available 38mm CTI 4 grain I242 motor. The total Impulse is 548.2 Ns (123.24 lb-s)
• The rocket shall utilize a dual-deploy recovery method. Teams may choose either the PerfectFlite SL100 or the Missile Works RRC3 altimeter.
• The rocket shall be recovered intact and undamaged to the extent that it would be able to safely fly again to qualify.
• The team shall utilize OpenRocket (free software) to design their rocket and simulate their flight. (Most commercial kits have .rkt files available for download.)
• One team member shall be assigned as the designated “builder” in order to get L1 certification (unless previously certified).

As we have mostly "newbie" members here in Florida and some extra budget, we are building three kits to certify three people. So far we have picked out a Binder Design Excel DD kit, a LOC Precision Fantom EXL kit, and am looking for a recommendation on a third kit. OpenRocket shows the Binder Design rocket getting about 100' higher apogee than the LOC Fantom but we all know OpenRocket can be off by a bit on occasion.

Can anyone recommend any 4" kits that will max out the apogee on a CTI I242 motor?

Thanks!
 
I'm not an expert, but I don't believe you can cert on a group project.

I'd go with either of those kits, and use wood glue instead of epoxy.
 
DizWolf said:
I'm not an expert, but I don't believe you can cert on a group project.

I'd go with either of those kits, and use wood glue instead of epoxy.
Click to expand...

Each member that will certify will build his own rocket (with supervision from others). That is why we are building multiple kits.
 
neond7 said:
Each member that will certify will build his own rocket (with supervision from others). That is why we are building multiple kits.
Click to expand...

Duh. I should have realized that. As for other kits , the madcow super DX3 should do well also.
 
Stay away from the glass and keep them light.


Because I am addicted, this is coming from my phone.
 
Do multiple simulations in OR to determine the sensitivity of max altitude to weight. I'm guessing that lighter is better (not always true.) Using the thinnest possible fins will help -- 1/8th ply or even balsa. Using a light avbay with minimal hardware will also help. A tail cone, if it's light, will help.
 
If max altitude is the goal with the above parameters, I'd suggest scratch-building...


Later!

--Coop
 
Coop said:
If max altitude is the goal with the above parameters, I'd suggest scratch-building...


Later!

--Coop
Click to expand...

+1, I most agree here.


Alexander Solis

TRA - Level 1
Mariah 54 - CTI RedLightning- I-100 - 6,345 Feet
 
It should have a tailcone, definitely.

Shortened Talon based design?
 
Thinking loopholes here. How much of the airframe needs to be 4"? Picturing a short 4" top section, necked down to 38mm for the rest. Keep the weight down. LOC tubing unglassed will have no problems with that I motor.

I have a Fantom EXL. I wouldn't recommend it for an altitude competition, but then again, I built too heavy. It's a pig. With and I300 and 3 airstarted G's, it barely made 3000'.

Wish my company would do something like this.
-Ken
 
Scratch or you could look at Madcow Patriot/Super DX3 to see how they compare weight and altitude wise to the others you have.
 
new2hpr said:
Thinking loopholes here. How much of the airframe needs to be 4"? Picturing a short 4" top section, necked down to 38mm for the rest. Keep the weight down. LOC tubing unglassed will have no problems with that I motor.

I have a Fantom EXL. I wouldn't recommend it for an altitude competition, but then again, I built too heavy. It's a pig. With and I300 and 3 airstarted G's, it barely made 3000'.

Wish my company would do something like this.
-Ken
Click to expand...

Listen to Ken, Thin walled tubes, 2 or 3 centering rings, shortest motor tube that can accomodate the motor and three, warp free lite plywood fins. You said you need some durability to survive and win so I suggest lite ply as opposed to balsa. Optimize on a favorite rocket simulation program. I believe Rocksim has an optimum weight calculator (ie. optimum throw weight for altitude). Keep rocket under wraps so the "enemy" can see it before the competition. Kurt
 
neond7 said:
I'm involved in a rocketry contest at work - basically, the office in Maryland has challenged the Florida office to a max apogee contest.
Click to expand...

I think this sentence just made just about everyone here extremely jealous. (I know it did me.) I really have nothing to add beyond that which others have already said.
 
using a slightly modified version of what I someday would like to do my L2 cert with, OR says 3300' - 3400'. quite likely a bit more tweaking would yield 3600'(I wasn't really designing for max altitude at the time :)).
Rex
 
neond7 said:
I'm involved in a rocketry contest at work - basically, the office in Maryland has challenged the Florida office to a max apogee contest.

• The rocket shall utilize a 4” airframe and may be a commercially available kit or scratch built design.
• The rocket shall use a designated commercially available 38mm CTI 4 grain I242 motor. The total Impulse is 548.2 Ns (123.24 lb-s)
• The rocket shall utilize a dual-deploy recovery method. Teams may choose either the PerfectFlite SL100 or the Missile Works RRC3 altimeter.
• The rocket shall be recovered intact and undamaged to the extent that it would be able to safely fly again to qualify.
• The team shall utilize OpenRocket (free software) to design their rocket and simulate their flight. (Most commercial kits have .rkt files available for download.)
• One team member shall be assigned as the designated “builder” in order to get L1 certification (unless previously certified).

As we have mostly "newbie" members here in Florida and some extra budget, we are building three kits to certify three people. So far we have picked out a Binder Design Excel DD kit, a LOC Precision Fantom EXL kit, and am looking for a recommendation on a third kit. OpenRocket shows the Binder Design rocket getting about 100' higher apogee than the LOC Fantom but we all know OpenRocket can be off by a bit on occasion.

Can anyone recommend any 4" kits that will max out the apogee on a CTI I242 motor?

Thanks!
Click to expand...

Why not do this with a Estes LPR rocket? Just as fun, and you can SEE to judge the winner. HPR is not something to ever consider as your first flight.
 
Last edited:
A V-2 like scratch build out of LOC tubing with a LOC nosecone with the altimeter in the nosecone shoulder and a tethered DD chute would be my first blush direction. The tailcone will be critical, followed by light weight. Maybe three fins...I'd have to play with the sims to see what's still stable but shaves off altitude.
 
Viperfixr said:
A V-2 like scratch build out of LOC tubing with a LOC nosecone with the altimeter in the nosecone shoulder and a tethered DD chute would be my first blush direction. The tailcone will be critical, followed by light weight. Maybe three fins...I'd have to play with the sims to see what's still stable but shaves off altitude.
Click to expand...

+1 This is excellent advice.

Going for max altitude, mass and drag are your enemies.

A boat tail or tail cone will help reduce drag. Three fins have less drag than four.

Eliminate the "standard" e-bay and one of the parachutes to reduce mass (weight)

As long as rules allow - drogue-less motor deploy, altimeter in the nose, Cable-cutter releasing the main... This saves a TON of weight. :cool:
 
RecoRocket said:
Why not do this with a Estes LPR rocket? Just as fun, and you can SEE to judge the winner. HPR is not something to ever consider as your first flight.
Click to expand...

Well, to throw more light on the subject, it is an aerospace company with the Maryland office using HPR to test some small electronics packages under a high-G environment. The contest was just to add to the fun factor.............
 
I have used upside down LOC transitions with the smaller shoulder cut off as tail cones. Not sure if it's lighter than other methods, though. A cardstock shroud would probably be lighter, but not as rugged, especially during landings.
 
I wanted to update everyone who contributed ideas - thank you very much. I wish the contest had more time and materials available to us as I would have explored some of these methods further. As it was, I had my hands full helping one of the members build her very first rocket. She did a great job, nothing like jumping right into building a dual deploy rocket for your first build!

One rocket is now complete (the Binder Design "Excel"), with the two others ready for final paint. We did go with a Binder Design "Bat" kit for the third rocket kit. OpenRocket actually simulates it reaching the highest altitude, although I'm not sure how with the large, heavy fins. It looks really cool, though!

Using OpenRocket, here is how the rockets simulate on the CTI I242 motor:

1. Binder Design "Excel" - 3623 ft
2. LOC "Fantom" - 3502 ft
3. Binder Design "Bat" - 3800 ft

I'll rerun the sims after I get the final weights when they are completed with all the recovery gear is installed. We will be launching at least one of these rockets (weather permitting) up at the Bunnell NEFAR launch on February 14th.

This could end up being a yearly contest, with different rules for each year. Once I help get a few more of the team down here level 2 certified, we could really start work on some interesting projects instead of just building kits.

IMG_9912.jpg
 

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