The Boostar two solid APCP rocket motor was successfully tested on the 4th of May 2020. The motor produced a thrust up to 7500N with an overall performance of 43kNs.
Motor diameter 130mm, 1880mm length, 19.1kg propellant, overall weight 34.8kg, 30g silicone/15g thermite igniter
Can i ask what binder you use for your apcp?
The binder is HTPB cured with MDI
Greetings!
Do you have an online reference that you may have started from for the various ignitor composition base formulas you’ve experimented with?
I have been working with ignitor compositions monthly for a few years now, continuously tweaking formulas and field testing; ignitors for very fast ignition systems (used for large motors, clusters, air-starts and etc.). I’m curious about the 2:1 use of silicone:thermite. What were the reasons for using this mixture? I personally can’t find much benefit over using a very fast and aluminized (fine AP-oxidized) ignitor composition with minimal binder content. Heat of enthalpy and/or heat of formation can be very high with the thermite blends, but their performance (vigor and speed) will depend highly on the thermite type used and binders used, methods, and many other variables.
I’m always curious to hear other’s input on their own work with energetic ignitor systems.
PM me on TRF, HyperSpeed, if you’re a member there and would like to chat. I’d enjoy that.
Thanks, and Godspeed!
Dear Hyperspeed,
The quest for an instant APCP igniter is something we share. Unfortunately, I have not found it yet. It still takes a few seconds before full pressurization.
I used about 15 grams of silicone/ AP (1:1) rolled into small spheres (6mm). These spheres burn quite fast (<1s) and the idea was that it would generate a bit more pressure. After analyzing the video, I’m not sure whether they actually improved the ignition of the 130mm booster.
In the actual launch I replaced the silicone for our normal thermite mix with a total mass of 45 grams. This is packed into a paper/ cardbox sausage which is hoisted into the top of the motor using a copper wire and an eye bolt on the chamber-side of the forward closure.
Typical composition of the thermite is: 14.4g Fe2O3, 2.5g Aluminium (fine mesh), 3.1g Magnesium (fine mesh). All components were mixed together in a pestle and mortar.
Although the thermite works fine for the booster, it failed to properly ignite the sustainer on the flight, resulting in a late ignition and a cato. Not sure why this happened.
You can find the launch movie on:
https://www.verticallimits.nl/?page_id=6845
kind regards,
Leo