Search found 187 matches

by Ray
Thu Dec 07, 2006 4:14 pm
Forum: Rocket forum
Topic: Physics xtra credit project: Build two 1-time-use candyrocks
Replies: 29
Views: 31671

Re: re: Physics xtra credit project: Build two 1-time-use ca

You will notice that almost all manufactured G motors have less than 62.5G of propellant (2 exceptions come to mind and they require a LEUP to own/use). Not true. ATF requires a LEUP for APCP propellants over 62.5 grams. Sugar motors, Hybrid motors, BP motors do not fall under this rule. I'm not su...
by Ray
Wed Dec 06, 2006 11:46 pm
Forum: Rocket forum
Topic: Physics xtra credit project: Build two 1-time-use candyrocks
Replies: 29
Views: 31671

re: Physics xtra credit project: Build two 1-time-use candyr

ISP will be down a bit for a 60/40 mix (fuel rich). Even if you assume an ISP of 100 you are in "H" class impulse.

Anything over 125g of propellant or 1500g liftoff weight needs a full waiver from the FAA.
by Ray
Wed Dec 06, 2006 7:58 pm
Forum: Rocket forum
Topic: Rocket parachute ejection
Replies: 28
Views: 37135

re: Rocket parachute ejection

Wondering how you'd keep the pin cocked in an acceleration rich environment? 10 g's is normal, 20 g's is common, 30 g's isn't unheard of...I've had flights in excess of 70 g's. Would take a pretty robust pin system to stay together. An ematch or christmas tree bulb etc, with a bit of black powder wo...
by Ray
Wed Dec 06, 2006 1:42 pm
Forum: Rocket forum
Topic: How Many Joules Through The Coil?
Replies: 1
Views: 5375

re: How Many Joules Through The Coil?

Estes has...minus the capacitor. BP is tough to make into a rocket motor. It needs to be very finely ground and packed at a high pressure. All of this makes it rather dangerous to do. Shocks aren't good for it, it can ignite. Once the motor is made there is a high likelihood that it'll have voids in...
by Ray
Thu Nov 30, 2006 2:16 am
Forum: Off topic forum
Topic: perchlorate cell
Replies: 3
Views: 4545

re: perchlorate cell

by perchlorate cell, do you mean a battery?

I can check with the two chemists that I know, but a bit more detail on the end game are in order...

Are you going for safety concerns?

How about suitability in the application?

I just don't know. PM me if you don't want the details public.
by Ray
Wed Nov 22, 2006 6:27 pm
Forum: Rocket forum
Topic: Nozzle Question
Replies: 11
Views: 12656

re: Nozzle Question

Copper doesn't work well as a nozzle, it melts at too low of a temp.

Its a bitch to machine too...sticky and work hardens very quickly.

If you want a green flame, barium nitrate is what you want...careful, its toxic.

Copper will give you a blue flame.
by Ray
Wed Nov 22, 2006 5:58 pm
Forum: Rocket forum
Topic: Nozzle Question
Replies: 11
Views: 12656

re: Nozzle Question

I've seen them work with solids...if you do it right, there aren't a lot of solids in the exhaust.
by Ray
Sat Nov 18, 2006 4:07 pm
Forum: Rocket forum
Topic: 1st Static test
Replies: 5
Views: 8706

re: 1st Static test

It had the right sound for a sugar motor...

So share the details, like Greg ask...Interested minds want to know.
by Ray
Sat Nov 18, 2006 1:07 am
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

The formula seems OK, but particle sizes aren't listed. Particle size is critical to the mix... I would stay away from the Mg though. Its tougher to get, and it can be a bit nasty to work with in small particle sizes. You can use aluminum instead. Whether you use Mg or Al, remember to wet the metals...
by Ray
Fri Nov 17, 2006 8:16 pm
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

The mesh size is going to be dependent on the oxidizer...and the effect you are going for. I work with AP most often, so I'll speak from that perspective, I am most familiar with it. I think the finest I would go on AP would be around 60 micron. Most of the stuff I've done is with 200 micron, but yo...
by Ray
Fri Nov 17, 2006 4:31 pm
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

Get the biggest scale you can afford. I have a 4000g 0.1g resolution Ohous digital balance. I also have a 7000g 1g resolution generic scale. The Ohous was expensive the generic scale was not. I use the fine balance for the small value measurements, and the generic scale for the bulk items (AP in par...
by Ray
Fri Nov 17, 2006 1:58 am
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

Re-reading this I realized that I didn't answer some of the questions you ask...so here goes. The altitude you get with the sugar motor on your rocket should be better than the estes BP motor, and should be less than your Aerotech reload. The ISP of the BP is lower than the sugar motor, but the suga...
by Ray
Fri Nov 17, 2006 12:06 am
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

Another way you can approach it is to burn some motors at pressures you believe will be "safe", be very conservative. Measure the internal pressures, and burn times. Plug the numbers into the spreadsheet from the OTHER book you bought (McCreary) and you'll get an approximation of the a, n and Isp* v...
by Ray
Thu Nov 16, 2006 11:13 pm
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

Sorry, updated my previous post...added some things...

I've managed to push one of my rockets (26 lbs) to 14,631 ft on a motor I've built. It was a 5 grain 75mm APCP motor.

A couple of my friends have gotten about the same altitude with some of the motors I've built.
by Ray
Thu Nov 16, 2006 10:52 pm
Forum: Rocket forum
Topic: Rocket calc ?'s
Replies: 16
Views: 16955

re: Rocket calc ?'s

There really isn't a good way to guess on the burn rate in a motor. As far as I know the only way to find out burn rate is to burn a motor, time it with reasonable accuracy, then calculate it based on web thickness. You want to do it in a ballistic motor for the greatest accuracy, for even better ac...