L1 Certification
- Thread starter BigRiJoe
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CoyoteNumber2
Original San Diego High Power Rocketry
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Uncertified motors cannot be used for certification. As far as I know, most/all motors made by CTI are certified.
markkoelsch
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Yes they can. CAR, NAR, and Tripoli have reciprocal certification agreements.
As long as they have been certified by one of the reciprocal motor certification organizations (NAR, TRA, CAR are the common ones in North America; NAR also recognizes motor certifications done by the Australian Model Rocketry Association) then you may use the motor for certification. Vmax CTI motors must not be used in a rocket that relies strictly on motor deployment.
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Steve
I flew V Max motors for years using motot ejection never having a problem. Is there any talk out there if the V Max issue will be corrected?
I flew V Max motors for years using motot ejection never having a problem. Is there any talk out there if the V Max issue will be corrected?
I haven’t heard any.
I’ve heard from others that they have no problems, but previous video evidence has shown that at least some of the Vmax motors fail too frequently.
What I don’t know (and I don’t know if anyone knows) is if this affects Vmax motors under certain conditions (altitude, vertical velocity, hot or cold ambient temperatures, etc.)
I think all of us would like to understand why it happened and if it still is a problem. I’d like to get rid of this constraint.
slothead
Slothead Tom
Sounds like a great (albeit expensive) research project.
I think if a person started collecting data: thrust to weight, flight velocity, body tube diameter, motor diameter, launch site elevation, elevation at burnout, and ambient temperature, there would be some kind of correlation.
My imperfect understanding of the events that led to the ban is that there was a drag race at a warm launch site where a very statistically significant number of the rockets snuffed their delays and crashed to the ground.
In a drag race people frequently fly high thrust to weight ratios, which is almost diametrically opposite of the original raison d’etre of these motors, which were as bowling ball lofters. High thrust to weight results in high velocity which causes high base drag. Is that a factor? I don’t know. Also, these rockets may have reached high altitudes before motor burnout, which would create a greater pressure drop at burnout. My understanding is that CTI hasn’t duplicated these delay problems on a test stand but there’s absolutely no base drag and not as much pressure differential at burnout on a test stand.
grouch
Well-Known Member
Interesting. I always used them in short stubby and light rockets to great effect. I pretty much flew a whole season with nothing but Vmax's and never had an issue. No way I was just lucky dozens upon dozens of times. What Steve is saying makes a lot of sense.
