VMAX warning - NAR Tripoli

[MaxQ]

I was not aware of this conversation going on in the propulsion section until I opened this email this morning.


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To our members:

The National Association of Rocketry’s Standards & Testing and Tripoli Rocketry Association’s Tripoli Motor Testing Chairmen are hereby enacting temporary Safety restriction for all Cesaroni Technology, Inc. VMAX reload motors equipped with delay charges.

We have both seen a growing number of VMAX flights using delay only recovery coming in ballistic at our flying fields, due to delay snuffing. It is believed that delay snuffing is likely a result of any extremely high burn rate motor completing its burn with a significant drop in pressure and/or temperature, breaking the burn ‘chain’, extinguishing or ‘snuffing’ the delay slug.

In light of the unpredictable VMAX delay performance and the resulting significant safety issues, we will now require all VMAX motor flights flown at NAR and Tripoli launch sites to have at least one electronic system installed for primary recovery. These electronics need to be able to handle the short G period of these motors to insure “Flight in progress” triggers. The safety restriction will be lifted when the manufacturer has provided documentation to the three motor certification committee chairman which includes the root cause analysis, the corresponding design changes undertaken by the manufacture to address the issue, and implements the necessary changes..

Any questions about this restriction may be sent to your respective organization’s motor test chair

Regards,

Steve Lubliner
NAR Safety Committee Chairman

Paul Holmes
Tripoli Motor Testing Chairman
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Copyright 2002-2014 by Tripoli Rocketry Association Inc.

 

[tim cubbedge]

This was posted yesterday in Propulsion.

https://www.rocketryforum.com/showt...ions-on-CTI-VMAX-motors&p=1589187#post1589187

 

[Worsaer]

It was posted to the Tripoli member forum, but a technical issue delayed the broadcast email to members.

 

[EeebeeE]

G185's, G250's, H400's, and H410's, which normally rely on motor deployment setups because the rockets do not fly that high are all V-Max motors and subject to this ruling.

I have often used a nose cone electronic single-deploy setup as a primary recovery system for some of my rockets that I want to make sure fires the deployment charge right at apogee. The system mounts into a plywood nosecone bulkhead with two screws. The "switch wire" extends aft and is pushed through the vent hole for a twist and tuck procedure. This will fit into a 29mm hole. It is a lot easier to retrofit a plyowod bulkhead into the nose cone of a completed rocket than it is to refrofit a rocket for dual deploy.

This setup only weighs about 3 oz., and I have not had any trouble with it. It is very easy to transfer from rocket to rocket, and you can make charges before a flight that can be used for it to reduce setup time on the field. Just remember that this, like all other DD systems, should be turned on when the rocket is pointed up, and before the igniter goes into your motor tube.

 

[EeebeeE]

Detailed layout of the SD sled.