Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > The Doctor is In! > Ask the Doctor
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-10-2009, 06:23 PM
yankee42 yankee42 is offline
Junior Rocketeer
 
Join Date: Feb 2009
Posts: 5
Question 29mm RMS Ejection Charge Problem

I recently started flying my 29mm reload case which i have had for a while. On its 2nd flight today, on a G71-7, the ejection charge did not fire. My LOC Weasel is now in pieces . When i cleaned the motor, i discovered that the delay had fired, but it had not ignited the ejection charge. Is this a common problem, or was it a mistake i made when i build the motor?
Reply With Quote
  #2  
Old 05-10-2009, 06:48 PM
brianc brianc is offline
Rivet Counter
 
Join Date: Aug 2006
Location: Orlando, FL
Posts: 173
Default

Sorry to hear about your Weasel...

Did you pour a small amount of BP initially and ensure it entered
the hole to touch the delay grain?

Did you add dog barf or wadding to fill any extra space in the well
after using the appropriate measure of BP? If not, was the motor/rocket
tipped nose down during handling?

Those are two common issues...
__________________
brianc -- NAR 83726 \ TRA 11640 \ L2
Reply With Quote
  #3  
Old 05-10-2009, 07:39 PM
Jerry Irvine's Avatar
Jerry Irvine Jerry Irvine is offline
Freeform rocketry advocate.
 
Join Date: Jan 2008
Location: Claremont, CA "The intellectual capitol of the world."-WSJ
Posts: 3,780
Default

There can be a variety of causes for this and "sit down for this", it is not a defect in the system.

One cause is grease on the delay face where the BP touches, which acts as an inhibitor.

One cause is delay blow-through time being sufficiently short the BP simply does not ignite. On numerous occassions I have seen CHARRED BP!!

One cause could be low air pressure which does not apply to your flight.

Solutions:

After assembling the motor and before installing the BP, run a drill bit through the transfer hole and slightly rough up the delay face. When you install the charge, shake it side to side a bit. Be sure you use REAL BP either 3F or 4F. Put a bit of tissue or flameproof wadding to fill the space above the charge before you apply the plastic cap or masking tape over it. Do not rely on a paper disc for retention. It does not reliably adhere.

Safety note: Delay "rough up" will result in a slightly shorter delay so make sure "rough up" involves about 1/64" or less (1/2 second coast) of material.

Someone should market a tool with these instructions attached and buy me drinks every time we see each other.

If you drill delays, most of the drilling should occur at the combustion chamber face, but 1/32" should occur at the ejection face to increase the flame action time.

In case you have not noticed, rocketry is an art MORE than it is a science.

This industry needs a global FAQ.

Jerry "told you so"
Reply With Quote
  #4  
Old 05-10-2009, 11:01 PM
yankee42 yankee42 is offline
Junior Rocketeer
 
Join Date: Feb 2009
Posts: 5
Default

Thanks for the solutions. I'll keep them in mind next chance I get to fly.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 05:10 PM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2024