Model Rocketry Discussion Thread

[ZodiaK]

Zodak... NAR is the National Association of Rocketry, Tripoli is another Rocket Association, they are the regulatory bodies (in the US)

As it stand in the US the general public can buy motors up to G class motors, to launch H or higher you have to be certified (ie you have to prove that your rockets wont be a danger and stay intact) Level one Cert allows you to launch up to I, then you have to get Level two, which involves bigger motors and a written test covering rules and regulations, that qualifies you to launch up to L motors, then you go for Level 3 which technically allows you to launch any size motor you can afford...

I dont know the rules in britain but http://www.ukra.org.uk/ is your organization

thanks be to you

[B787_300]

Zodiak IIRC the brits have essentially copied the US system but it is harder to get motors and launch them over there.

[B787_300]

oh wow, it has been a while since anyone has posted in this thread...

anyways have a nice picture of the rocket that I will hopefully launch next weekend

[ZodiaK]

ooh! I look forward to the pictures of the launch!

[PB666]

It's good to see this restarted

It's too much hassle to launch rockets in the UK, so I'll stick to doing it virtually, have fun guys

Thats cause UKers do stuff like this:

[B787_300]

finally done painting the rocket, just simmed it out

5145 ft apogee , 653 ft/s max, .59 mach max

[ZodiaK]

looking awesome!

[B787_300]

Thats cause UKers do stuff like this:

granted that was done with full permission and with adequate safety considerations. Now the ausies on the other hand... http://www.worldrecordrocket.com/index.php/the-rocket

[dharak1]

I launch small model rockets occasionally. The largest I've ever launched had 2 C6-5 engines on it. I've been thinking about 3D printing rockets in parts. I have one that I printed a while back that's about 5 inches tall. No chute or wadding though. It also has no real way to launch as I didn't include the little tube that you put them on in the print. My newer designs have that fixed and use a paraboloid nose instead of a cone. The largest rocket I have ready to print is over 8 inches tall and has a variety of noses to select from because it's segmented. I could post pictures of the one I have already if anyone wants.

[TythosEternal]

finally done painting the rocket, just simmed it out

5145 ft apogee , 653 ft/s max, .59 mach max

https://i.imgur.com/IzQuy50.jpg

Oh my, that's a beauty! Great paint scheme (and not just because it's in my alma mater's colors)!

[Armchair Rocket Scientist]

finally done painting the rocket, just simmed it out

5145 ft apogee , 653 ft/s max, .59 mach max

What's the giant motor case on the right? It's hard to tell with perspective and all, but it looks like an "O" or bigger.

[B787_300]

Tythos where did you go to school

and Armchair, it MIGHT be used to put a rocket across the boundary of space... it would be a P motor IIRC

[dharak1]

I also see canister of N2O back there is that for hybrid engines?

[B787_300]

Dharak1, sort of? that is both being used for hybrids and then it will also be used to store i think Helium for a LF rocket

[B787_300]

So launch was yesterday pics are coming soon . Altitude was 4079 ft

[Budgie]

Congrats, must have been great!

[B787_300]

oh it was and I wish i had taken videos (I am hopefully waiting on one of the club photographers to have taken one). It was a nice SLOW burn (about 7 seconds) and it performed beautifully. The drogue poped out at apogee and it descended quickly to ~500 feet (was supposed to be 700) and then the main deployed and it touch down in the same field that we were launching from.

[FishInferno]

I launched a few rockets over the weekend, here is a pic of the Estes Crossfire:

Granted, its nothing like B7's, but I think its a cool shot

[Whirligig Girl]

Am I the only one who dislikes the fact that so much of the space in a rocket body goes to waste? I mean, just that one little engine at the bottom? I know the long cardboard tube is needed for stability, but still. I wish I could have a really long engine.

Maybe that's just the "big boosters" feeling from KSP.

[FishInferno]

Am I the only one who dislikes the fact that so much of the space in a rocket body goes to waste? I mean, just that one little engine at the bottom? I know the long cardboard tube is needed for stability, but still. I wish I could have a really long engine.

Maybe that's just the "big boosters" feeling from KSP.

You could put an engine that fills up the whole body tube, but it would be wayyyyy overpowered and you would probably not get the rocket back.

High-power rockets have larger enigne-to-body-size ratios

[Skyler4856]

Hey, does anyone know of an equation that can be used to calculate the exhaust velocity of a water bottle rocket?

[B787_300]

skyler there are a lot... How fast will the water be leaving the mouth of the bottle? are you using a Nozzle? what is the PSI of the tank?

[Camacha]

Hey, does anyone know of an equation that can be used to calculate the exhaust velocity of a water bottle rocket?

I am interested in building one for someone too, but I do not really know where to start. Maybe I would better just build something and go from there.

[B787_300]

google is yall's friend

[Bill Phil]

Hey, does anyone know of an equation that can be used to calculate the exhaust velocity of a water bottle rocket?

Pressure times area of escape gives you force, and then you divide that by the mass flow to get the exhaust velocity. Assuming you know all those values...