Well I finally quit talking about it and did it. I built a 3 inch
rocket in April for clustering RATT Hybrids. The "Better RATT Trap"
is a 3 inch airframe that is about 100 inches in length. She is built
to fly on 4 I90's. I was going to fly her at LDRS but was one I90
short of a full load.
Saturday's Launch with the Jackson Model Rocket Club was held at our
winter venue...A farm field with about a square mile of recovery area.
It was high time to let her loose. I arrived at the field with the
bird fully prepped and waited until early afternoon for the wind to
die down. She was loaded with 2 I90's and 2 H70's. I had Doug Pratt
whip me up a manifold that allows me to fill all 4 motors at the same
time....worked like a charm.
After waiting a while we walked her out to the pad in about a 12 MPH
wind. We used an extended rail.....which blew over as we were walking
back to the LCO desk. The wind had picked back up... Popped both Acme
Rail Guides off of the airframe...Thought it was all over at that
point. However in true JMRC fashion I was assisted in installing rail
buttons at the pad....good friends...rail buttons and CA glue....what
a combination. She was ready to go...AGAIN!!!!
We walked back to the LCO desk and tanked her up. The H70's began to
vent after about 8 seconds followed closely by the I90's after a 5
count the LCO (Scott Miller of SFSM Industries) pushed the "GO"
button. 2 of the motors came to life immedietely and she beggan to
crawl up the rail.....Whats up! Then she shifted gears....post flight
analysis of the video shows the 6 feet of "fill tube umbilical"
stretching until all burned through. She lept off the rail and at 300
feet ....the second I 90 and kicked in to full thrust and she shifted
gears again and dissapeared into the clear blue sky going 3980 feet
per the Adept ALT S25.
Post Flight analysis:
- Get all 4 motors to light at once:
All 4 lit but slightly more "sequencial" than I would have liked.
planning to use 2 igniters per motor paint the igniter grain with
Pyrogen or use dipped ematches....
- provide a mechanical means of freeing the bird:
looking at a static jig to cut fill tube at point of initial
thrust...it's clear in my mind but translating to paper at this point
is somewhat muddled.
- Need a good support team:
couldn't have done it with out the help of Scott Miller and the
encouragement (and video) provided by Todd Moore (Sky Ripper Systems).
There is an entire cast of supporting characters including Clayton,
Roger, Shawn and the entire JMRC Club.
- Do it again REALLY SOON:
Get my hands on 2 more I90 cases for the November Michigan Team1 launch
at Three Oaks and do it like I meant to when I designed her....
- Try Something New:
Need a "check valve" system...I want to airstart some RATT motors!!!!
Your comments and suggestions are appreciated.
Mark A Palmer
TRA 08542 L3
- posted 18 years ago