Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > Projects
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 06-16-2019, 07:18 PM
5x7's Avatar
5x7 5x7 is offline
Sometimes collector
 
Join Date: May 2008
Posts: 1,786
Default Adjusting Delays - Q-Jet

I have been adjusting Aerotech delays for over 25 years using their approved drill method, which has been officially incorporated across most of their line. They have released at least three tools through the years to make it easier to do.

Quest released its A through D Q-Jet motors, and second generation packaging dropped Quest from the label and the motors are branded Q-Jet by Aerotech.

In line with other Aerotech products, I thought it would be simpler to buy the longest delay if it could be adjusted. AT single use motors are adjusted through the forward touch hole but this is problematic for Q-Jets because the ejection charge cap is down pretty far, and although others have gotten it out, I don’t think it would be worth while to have cap removal, then dump, drill, replace and recap as a good option, In addition, drilling from the forward end causes delay grain to remain after the change goes off and that still burns, barbecuing the rocket above the motor.

I found a 2” long 5/64” diameter bit fits through the nozzles and reaches the delay. As a first test I took a 1/16th off a B4-6 to make it a four. The flight went great with just over 5 seconds from liftoff to ejection which confirms to me the regular delay material is being used. The pictures show the bit, with tape marking the depth to drill too, and the delay removed. Try this at your own risk, the drilled hole is small so there is a chance if the hole is not cleaned out well you will get the normal delay. A bigger bit should fit in Ds and Cs. If you try it take note that every motor needs to
be measured, where the delay is in relation to the nozzle can vary even between motors of the same class and delay. The other thing to remember is the delay is rubbery but it is holding back the pressure in the motor so don’t cut it under 4 seconds or the shortest delay offered.

Getting the longest delay is nice because there is no Estes equivalent.

Flight Video
Attached Thumbnails
Click image for larger version

Name:  9A15E3F4-AB37-4B03-A6C2-A8A5457B7F3E.jpeg
Views: 77
Size:  774.0 KB  Click image for larger version

Name:  F73AAFA0-1198-44CC-83E4-B966E1554168.jpeg
Views: 65
Size:  1.22 MB  

Last edited by 5x7 : 06-17-2019 at 07:50 PM.
Reply With Quote
  #2  
Old 06-16-2019, 08:39 PM
ghrocketman's Avatar
ghrocketman ghrocketman is offline
President, MAYHEM AGITATORS, Inc.
 
Join Date: Jul 2005
Location: Nunya Bizznuss, Michigan
Posts: 13,443
Default

Excellent !
I will only order the long delays from now on.
Only really interested in their 18mm D, which is a good substitute for the old 18mm Cox D8.
__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !
Reply With Quote
  #3  
Old 06-16-2019, 10:04 PM
5x7's Avatar
5x7 5x7 is offline
Sometimes collector
 
Join Date: May 2008
Posts: 1,786
Default

I just ordered a 3 inch bit and a stop collar from McMaster Carr that will make this a 30 second job.
Reply With Quote
  #4  
Old 06-17-2019, 12:30 AM
BEC's Avatar
BEC BEC is offline
Master Modeler
 
Join Date: Feb 2009
Location: Auburn, Washington
Posts: 3,643
Default

This is very interesting. I’m not sure I personally would act on this information, but I appreciate knowing this. Thanks.
__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE
Reply With Quote
  #5  
Old 06-17-2019, 07:51 AM
Ez2cDave's Avatar
Ez2cDave Ez2cDave is offline
Banned
 
Join Date: Mar 2005
Location: Raleigh, NC Area
Posts: 1,743
Default

Quote:
Originally Posted by BEC
This is very interesting. I’m not sure I personally would act on this information, but I appreciate knowing this. Thanks.


Don't be scared . . . You won't "blow your hand off" - LOL !

Dave F.
Reply With Quote
  #6  
Old 06-17-2019, 07:31 PM
BEC's Avatar
BEC BEC is offline
Master Modeler
 
Join Date: Feb 2009
Location: Auburn, Washington
Posts: 3,643
Default

Not too worried about that.....
__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE
Reply With Quote
  #7  
Old 06-17-2019, 08:00 PM
5x7's Avatar
5x7 5x7 is offline
Sometimes collector
 
Join Date: May 2008
Posts: 1,786
Default

Quote:
Originally Posted by BEC
This is very interesting. I’m not sure I personally would act on this information, but I appreciate knowing this. Thanks.


You bet, I personally wouldn’t start with Q-jets if you had never shortened a delay,the 24-60 case has model rocket motors with adjustable delays and you get a better feel for it when you can see what you are doing. I got started when the 24-40 reloads long delay were the full length and the delay spacer for the next shorter delay was a hard fiber disk that would survive the flight and could be reused. So to make a 7 into a four, you would hold the spacer next to the delay and slice off that length, then use two spacers instead of one. When AT switched to thin paper spacer rings it was back to drilling.
Reply With Quote
  #8  
Old 06-18-2019, 05:42 PM
BEC's Avatar
BEC BEC is offline
Master Modeler
 
Join Date: Feb 2009
Location: Auburn, Washington
Posts: 3,643
Default

I'm familiar with drilling delays in the context that I fly 24 and 29mm CTI motors. I also have the tools for both the new RMS motors (such as the 24/60 loads you allude to) and the other one that uses a similar but different tool (I forget what AT called that one). But I've not thought of drilling delays on SU motors through the nozzle....
__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE
Reply With Quote
  #9  
Old 06-18-2019, 07:07 PM
5x7's Avatar
5x7 5x7 is offline
Sometimes collector
 
Join Date: May 2008
Posts: 1,786
Default

I think the universal delay drilling tool that's not universal unless I am missing something.
Reply With Quote
  #10  
Old 06-18-2019, 09:08 PM
5x7's Avatar
5x7 5x7 is offline
Sometimes collector
 
Join Date: May 2008
Posts: 1,786
Default

Here is a simpler way to do the drilling with a longer bit, a depth stop and 1/32” washers, sold as shortening shims. Procedure is
1) Stack as many washers as you want seconds removed on the nozzle, plus one to drill on.
2) Put depth stop loose on bit and bit into nozzle.
3) with depth stop resting on washers, tighten depth stop.
4) Remove all washers except the one against the nozzle.
5) Drill until stop bottoms on washer on nozzle and clear shavings.

First the items:
Attached Thumbnails
Click image for larger version

Name:  B172465B-92EA-4F51-BD07-A916545E1117.jpeg
Views: 58
Size:  1.73 MB  

Last edited by 5x7 : 06-18-2019 at 10:02 PM.
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 05:41 PM.


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