View Full Version : Rockets

02-07-2002, 04:12 PM
Well, My son and I are aiming to get our scratch-built rocket ready for the fourth of July. It's about six feet (2 meters?) tall, weighs about 8 pounds (3,600grams), and 7.7 inches (196 mm) in diameter.

I'm loading five (5) Aerotech G80-7 motors for a total of about 600 Newtons of total impulse. According to the calculations that I've performed, maximum altitude should be about 1,100 feet (323 meters) which should be reached in 7.3 seconds at an airspeed of 263 MPH (117 meters per second).

We'll see what happens. It might be an exciting event! LOL !!! Everyone is concerned about what safety equipment to bring with them to the launch!


12-07-2002, 05:44 AM
So, Fish, what happened with the launch? Still waiting for it to come down?


12-07-2002, 07:40 AM
yea, come on, give us the info and we want pictures as well :D

12-07-2002, 02:41 PM
Well, the launch didn't go as scheduled..... the Factory that produces the motor and ground support gear that I use.... BURNT DOWN ! ! ! . That must have been one heck of a blaze!! :rolleyes:

I was left short one motor, and four igniter clips to launch. BUMMER!! :mad:

I seem to have trouble "imbedding" photos in the forumn. when I try to post an image, it seems like the program is searching the net for the image. Any tips, Webram ?

My sister has some video and maybe some picks of a smaller scratch-built rocket we made, on a photo web site (for pictures that she takes with her digital camera). That rocket would do 2,000 to 3,000 feet on one 120Ns motor. I'll see if I can get a link for y'all.

12-07-2002, 11:18 PM
Web site Link?? Herefishy??

I would have thought you would invite us all.....I mean "sum of us !!! " hic hic.......to see the launch!!! in real live action!!! LOL

Good luck on the launch..

15-07-2002, 11:33 PM
well, here's a pre-launch photo of the small rocket:

06-05-2003, 06:27 PM
Well !!!!!!

We finally launched the big one!

here's a link to the video of the launch



Also attached is a photo of the motors, loaded and wired to fire.

06-05-2003, 07:29 PM
Don't forget to go to the video link above... but here's another more photo:

06-05-2003, 09:15 PM
bloody heck, thats a big rocket !!!!

07-05-2003, 08:14 PM
Hi Fish

Congrats on the launch - the little one sure had a big smile.

The link to the Movie didn't work for me but - hey I'm really pleased for you - must be some achievment after all the hard work. Do you get to retrieve the rocket after it lands?

You mention that the rocket was rated at 600 Newtons but if you multiply the rocket numbers by the power factor you only get 400 Newtons (5 x 80) - is there some special way of determining the overall power?. I find this rocket building really interesting and would love to see close up this sort of launch, I bet the old adrenalin gets pumping during countdown


07-05-2003, 08:23 PM
Hi frank. As far as determining total power (impulse) you would multiply the 400 Newtons by the 1.5 second burn time to get 600 Newton-seconds. The "80" indicates average thrust. :)

... and yes the idea is to be able to re-launch the rocket. Parchtues are primarily utilized, however there are even competitions on different types of recovery such as "helicopter", glide, streamer... etc.

You might be able to view the video at the club website.. I believe the webmaster formatted it in Quicktime. click on the archives link and the launch date May 3rd, 2003. There are other pics you can check out too.


As far as motor rating, you can check out a rocket mgr's website for more information.


Here's another cool rocket link


07-05-2003, 09:04 PM
The link worked this time :)

What height did the rocket reach? How do you measure that?

Sorry, Lots of questions, I know


07-05-2003, 10:37 PM
Just as a reminder... pictures and videos of the launch can be found by clicking the "archives" link on the webpage


For prediction of rocket altitude, there are many online calculators that you can use. This is my favorite:


The rocket that you observed was calculated to go to an altitude of about 1,052 ft in 7.7 seconds at a maximum speed of 235mph. I think that came out to an acceleration of about 9g's.


From what I observed at the launch, I think my predictions were rather accurate. A lot of these guys who ingage in "high Power" rocketry" shoot for 13,000 to 20,000 even 30,000 feet altitude !!!! In these applications, electronics are usually employed to control ejection recovery charges, record altitude and velocity, and even video recordings of the flight!

As far as measuring altitude, as I stated, a lot of guys like to have electonic payloads that record altitude. But you can obtain a device to use from the ground from which you can use "eye" spotting and a trigonometric function to estimate altitude.... somewhat like the antiquated device used for maritime in the old days to determine latitude... I don't recall what that device is called... of course at 30,000 ft, it wouldn't be very effective!

10-05-2003, 09:12 AM
If you would re-visit


and go to "archive"... and photo albums... and even click on the may 3rd launch photos.. you will find more excellent pictures... particularly of my Flying Tiger... Noah Schuster is a world reknown rocketry photographer.. and you should see pics he just submitted to the webmaster....

You can see the ignition wires hanging from the Tiger and fire from the motors, as it leaves the rail.. Awesome!

Go to the bottom of the picture page.


PS... the Flame Dawg is from my shop.... #1 son is in charge of fin design on the VCP software, and paint. You can see him smiling ear-to-ear in the Fflame-Dawg photos.... "Flame Dawg" is a really nice, stable ship.... ...

16-05-2003, 04:19 AM

I was really flattered with your interest in the sport.... have you pursued the activities availble "across the pond"? Let me now what you find. It's really a lot of fun, and you get to hang out with a bunch of "Rocket Scientists" !! LOL

Holler back.

se ya'


16-05-2003, 07:19 AM
I can't really say that I have - time being of a premium and all. There have been a few launches over here that have been in the press, mostly just the local tv news.

I don't think that it is as big a sport over here but there are some dedicated guys building as we speak.

I recall that there is one guy who has just had a recent launch and his dream is to build a sucker big enough to take himself into the air? :eek: can't recall if he lives on this side of the pond or yours.

I used to jump out of airplanes when I was a bit younger which was great fun and I can imagine that you get a similar buzz when your baby lifts off after all those loving hours of labour.


20-05-2003, 09:52 PM
Surfing the net I stumbled on this little gem http://science.howstuffworks.com/rocket1.htm - lots of info here. Some of the calculations look long winded - do you do any of them yourself herefishy?


27-05-2003, 06:37 PM
I had made a little spreadsheet that performed the Barrowman's Equations for Center of Pressure.