TERRIER/SANDHAWK (SPORT SCALE)

INTRODUCTION

Not too long ago a good friend of mine, Jason Toft, built a fine BT60 based 
Terrier/Sandhawk that utilized gap staging for terrific 2-stage flights. I 
was always taught to tape motors together for staging and was thus baffled 
at the concept of a booster motor igniting an upper stage motor with a 
significant gap between the two. Inspired by his rocket and curious to try 
my hand at gap staging, I thought I'd build my very own T/S except this one 
would be much simpler and much smaller.

The theme of this entry is to introduce the modeler to gap staging utilizing 
basic building techniques found in most 3/4 finned rockets while 
constructing a rocket giving a scale appearance. Construction can be 
completed in less than a day and utilizes parts found in most rocketeers' 
spare parts bins. With a bottle of white or yellow glue, basic hobby tools, 
and some attention to detail, this scratchbuild can be had at a near Level 2 
kit recommendation.

NOTES FROM MY FIRST FLIGHT

2/7/04 - SEARS572...Headland, AL

"It flew!...and it flew great! I finally broke out the SS T/S and flew it at the SEARS572 Tour de Deuce launch this past weekend. I decided that for its first flight I'd go with a C11-0/A8-5 combination just to guage altitude and see how cleanly the gap stage would be. Folks, I don't know what the C11-0 burn time is, but the rocket *maybe* went 125ft when I heard it 'pop' stage the Sandhawk. This rocket isn't even all that heavy! The A8 then took it another 500ft or so. I'm looking forward to a nice D12/B6-6 flight." 

Rocket Specs:

Overall Length - 27.75"
Diameter - .976" (BT50)
Recovery - Mylar Streamer or 12" Parachute
Guidance - 3/16" Launch Rod
Ignition - Standard controller recommended for Estes or Quest type motors
Motor Selection - 
Terrier: *C6-0, C11-0, D12-0 
Sandhawk: Single Stage...A8-3, B6-4, C6-5; Upper Stage...B6-6, C6-7 motor 

(*Build or utilize a 24/18mm MMT adapter)

PARTS LIST

Sandhawk:

Nosecone - PNC50 (Estes Alpha)
.5oz Clay noseweight
Body Tube - 16" BT50 dia. (FlisKits BT-50-18)
18mm Engine Mount - (FlisKits EMK-18-50)
1/8" Fin stock - (FlisKits FSB-4-3-12) See pattern sheet
1.5" X 3/16" Launch Lug - (FlisKits LL-2-2)
18" Kevlar -OR- 1/8" X 18" Shockcord (FlisKits SLK-3508-120/SC-1-36)
1.375" X 18" Mylar Streamer (2-stage flights)
-OR-
12" Parachute (Single Stage flights...FlisKits PCP-16)
Shockcord uses standard paper mount.

Terrier (Booster):

BT50 Tube Coupler - (FlisKits CPL-50-01)
Body Tube - 8" BT50 dia. (FlisKits BT-50-18)
20/50 Engine Block - (FlisKits P/N CRP-20-50)
1.5" X 3/16" Launch Lug - (FlisKits LL-2-2)
*Note 24mm minimum dia. MMT - use 24/18 MMT adapter for 18mm motors

CONSTRUCTION NOTES

The Terrier/Sandhawk features a unique method of staging called "gap 
staging." To ensure proper staging of motors, drill 2 1/8" vent holes 
opposite each other and located just below the stage coupler in the Terrier 
booster to enable reliable ignition of the upper stage. Failure to do so 
could result in the stages separating due to pressurization and separation 
before upper stage motor ignition.

To preserve the finish on the rocket, use a flat strip of balsa to create 
launch lug stand-offs.

FLIGHT PREPARATION NOTES

Neither the Terrier booster or Sandhawk rocket utilize a method of positive 
motor retention. Ensure a tight friction fit of the motors on both rockets 
so that neither motor ejects before staging or recovery device deployment.

For smaller fields, be sure to use discretion on motor selection and 
recovery device selection. For 2 stage flights a streamer is recommended for 
the Terrier rocket.

FINAL THOUGHTS

If you are not too concerned about the actual scale data but would like a great scale looking rocket, you should try your hand at this sport scale Terrier/Sandhawk. It's a great alternative to other 2 stage rockets. Enjoy!

Eugenio Cebollero, NAR #81161