Rocket Challenge on Discover

Whoa... don't you think this is all _way_ overkill for a typical HPR model?

How am I going to measure "thrust vector alignments and aerodynamic natural frequencies" etc. on an average HPR-sized bird?

Have you ever made such calculations and analyses for anything smaller than a "full-sized" sounding rocket?

Do you really think calculating "flex body gain and phase margins" is going to tell us anything new and useful about how a BSD Sprint or a LOC Magnum is going to fly?

-dave w

No. It is not even instructive on sounding rockets under 40 miles altitude.

In fact my own launch application process told me most dispersion error is actually introduced by "wind weighting" as it is less understood than simple ballistics.

Overcorrection is rampant. I have data to support it.

Just Tech Jerry

Apogee Splash does a subset of this.

All joking aside, maybe there's a market for a heavy-duty replacement cover for the E-Z-Up that ISN'T so easy to tear? Trampoline material, maybe?

David Erbas-White

David Erbas-White wrote in news:Z4gtb.10195$Q64.4028@fed1read03:

No, it is limited by the number of raindrops contained in the volume you move through over the time interval considered.

len.

snipped-for-privacy@aol.com (GCGassaway) wrote in news: snipped-for-privacy@mb-m10.aol.com:

I make an effort to do exactly that, at least to watch the liftoff and get some idea of what to expect for the next ten or twenty seconds. I also prep a good distance away from the launch area.

len.

Jerry Irvine wrote in news: snipped-for-privacy@corp.supernews.com:

Jerry, this gets tiresome. TRA and NAR don't require explosives permits, BATFE does. And both organizations are suing BATFE for misclassifying APCP as an explosive. So what more do you want?

len.

Brett Buck wrote in news: snipped-for-privacy@pacbell.net:

And all of these things will not reduce the risk to zero. I'd still have to pay attention to what's going on. So I prefer to just pay attention in the first place and forego all this unnecessary ancillary BS. Almost all risks associated with sport rocketry are mitigated by paying attention and using common sense. Anything else is like trying to legislate against stupidity.

len.

Brett Buck wrote in news: snipped-for-privacy@pacbell.net:

Not related to sport rocketry.

len.

I am very interested in obtaining test data of thrust vector misalignment in MR and HPR motors.

Hey, you forgot dynamic spin balancing, and avoiding roll rates that cause instability.

worthless. Why 5 Hz?

I'm very interested in this also. Please send me a copy of your report or procedure detailing how you do that.

A factor of two margin is way too high for well developed and tested NAR contest models. It is not high enough for "rudimentary" analysis. Of course the more complete the analysis and/or testing is, the lower the structural margin can be. Structural failure is relatively low on the range safety scale. Far more deadly are lawn darts, catos, and launch mishaps.

Log rolling is actually difficult and takes much skill and practice. Even just getting to the point where you get up on the log before falling off is difficult.

Alan

Gary wrote in news:3FB59096.4020507@below:

Before you jump on Jerry's bandwagon and savage the NAR, please bear in mind that when this was done, it eliminated state to state variation in the laws covering model rocketry, and made it possible for most kids to fly model rockets without running afoul of the law. At the time, it struck a lot of people as a pretty good move.

Admittedly, things are different, perhaps only because this strategy made it possible for them to become different.

OK, all you Monday morning quarterbacks can jump in now.

len.

Jerry

The United Technologies plant in south San Jose, CA (actually, Coyote valley, but that's not relevant) had two explosions in the space of about a month. One occurred during an idle time, and the other during maintainence. I belive there was one fatality. I woul d search the San Jose Mercury News archives for the articles, if you care to investigate further.

These are just the ones that made the news. Small accidents happen all the time (like, say, counterboring a fully-constructed motor to raise the thrust curve, and blowing up the drill press) happen at a reasonable frequency. Generally, no one gets hurt because they do it in closed cells with remote operation. The generally held notion that AP can't explode (at least in the layman's sense of the word), however, it demonstrably false.

Brett

Alan Jones wrote: >>CG offsets in the >>model, and very careful alignment inspection of the models, would also >>be advisable to prove that the models are not going to turn in flight >>to >>such a degree that they will impact outside the range limits. >

I didn't forget it - I intentionally left it out. I figure that for a screening process, you could take your chances - assuming the rest of it was OK. What a hybrid might do with a significant roll rate and half a tank of oxidizer is also an open question.

I amended this by saying it might be too high. The point was to give you some "figure of merit" that measured the transient response, which would lead to some way of assessing the trajectory dispersion. Also limits the inflight AoA to something you might consider linear that validates the undoubtedly simple assumptions in the stability analysis.

Brett

But related to production of propellant and complete motors that (as a bragging point) is "identical to what they use in the Space Shuttle".

Brett

Brett Buck wrote in news: snipped-for-privacy@pacbell.net:

Len responded:

Not only that, but if I remember correctly the two incidents at that plant did not occur during propellent mixing and were not caused by propellent.

That's fine, if you're considering only the ballistic impact point... ideally, we could then predict where any lawn darts would land and say "don't stand right _there_" - but with normal recovery, wind can still take it anywhere.

Most "heads up" calls I've seen at Fresno HPR launches involved big birds under chute descending into the "populated" areas of the field, rather than lawn darts.

-dave w

Brett Buck wrote in news:bpb6fp$13i3 @cui1.lmms.lmco.com:

And like most bragging points, it's a stretch of the truth. Sport rocketry APCP is much less energetic than the SRB propellant, and many of us would like to see you get some to explode -- really explode, not overpressurize a container.

len.

Did you see _60 Minutes_ last night? They seem to think that every chemical plant in America needs Fort Knox security now.

While some additional security might be beneficial in some cases, I can't help but wonder if it won't be long before Mike Wallace is standing in front of the 7-11 asking folks what they're gonna do with that 20 gallons of gas they just put in the tank.

Doug BTW: I've played the course next door to the Gold Vault...