#### Fred Garvin

##### Male Strumpet

- Joined
- May 22, 2013

- Messages
- 1,686

- Reaction score
- 5

**:**

__NARTREK Bronze__60 Second Flight, Parachute Recovery, B motor max.

60 Second Flight, Streamer Recovery, B motor max.

2 Stage Flight

D motor or larger flight

I've completed

**:**

__NARTREK Silver__Payload Flight

3 Motor Cluster Flight

30 Second Glide Recovery Flight, B motor max but try to do it on an A.

Scale Model Flight and Evaluation

Now I'm working on the final level:

**. Since I haven't seen any build threads on this, and search turns up only stuff from 2004 and 2006, I thought I'd do a Build Thread to document the journey and also maybe get some tips and help along the way. I have Rocksim and the following to use as reference:**

__NARTREK Gold__*Handbook of Model Rocketry,*G Harry Stine

*Model Rocket Design and Construction*, Tim Van Milligan

Centuri TIR-33

*Calculating Center of Pressure*(supplied with NARTREK Gold packet)

Centuri TIR-30

*Rocket Stability in Flight*(referenced in NARTREK Gold packet)

Centuri TIR-100

*Altitude Performance*

The requirements for

**are to design, build, fly and mathematically predict performance and determine drag coefficient of a scratch built rocket.**

__NARTREK Gold__- Design your own model rocket. It may be a sport, contest or payload model. Compute the Center of Pressure (CP) using the Barrowman Method or calculate the CP using one of the available computer programs. Estimate the Center of Gravity of your model with the largest expected rocket motor installed. Evaluate the static stability of your model. Compute the predicted altitude of your design, assuming various drag coefficients (CD). You may do this using the Centuri Report TIR-100 or Estes TR-10 and TR-11, or you may use one of the commercially available or freeware programs available on the Internet.
- Build and fly your rocket design. Determine the altitude to which it flies by using standard tracking system methods or by use of an on-board altimeter. You may also use a stop-watch and the drop-streamer method described in
*Handbook of Model Rocketry,*Chapter 17, by G.Harry Stine. Make at least three (3) flights with each of at least two (2) types of motors and compute the average altitude achieved for each motor type. This is a minimum of at least six(6) flights. Using this data and your previous flight performance calculations, estimate the actual drag coefficient of your model. Record the flight information and the results of your calculations on the Flight summary Sheet that came with your Gold packet. Be sure to complete the comparison of predicted to actual performance.

I've got a design in mind and I've been working on draft sketches of it. My objective is to build a rocket that is very simple to model, reliably predictable, and uses best practice methods and "Rules of Thumb" for aerodynamic stability. I want to avoid anything crazy or clever in design. Just keep it simple, traditional and build a really great flier. After quite a bit of sketching, changing, and thinking, I've come up with a good design that is essentially an Astron Sprint with Nike Smoke Fins.

Once I finish a decent quality design drawing (not a freehand sketch), I'll post it in this thread along with my logic for each design element. I've got parts on order from FlisKits and RocketChutes, and I'll do a Rocksim on it to do all the stability and performance modeling. It's been 30+ years since I've had to do any advanced math, so attempting the calculations by hand is going to be hard for me....unless anyone is interested enough in this to maybe help out. After all, it doesn't say anywhere in the packet that you can't ask for help....quite the opposite really; they encourage it! I'll try to get my design drawing done, scanned and posted soon. Sunday is going to be a good day to stay inside....we're going from a high around 76 on Saturday, to 21 by Sunday morning! An Arctic front with a 50+ degree temperature drop in 12 hours. December in Texas. Shorts and tshirts one day, snowmobile suits the next.