I had attached just the top of a second bottle to act as a nose cone. No parachute yet, I was hoping the nose would fall off at apogee and prevent it nosing in.
On the first launch the bottle floated in slow and landed on it's side. No nose section separation.
The second launch the bottle nosed in and landed hard! I had to work on a more reliable recovery.
The Stratofin instructions tell you to cut off a bottle top 4" from the tip. For me (and the bottle I used) that was too tight and prevented the nose from falling off.
I trimmed back the bottom of the nose section a bit shorter.
Today I tried with a 12" Odd'l Rockets parachute.
The tape on the sides was to keep the nose cone in place while I walked to the schoolyard.
I had five attempts. On the first try the rocket wasn't fully locked down and went up 20 feet during the first pump. I'll have to adust the friction fit of the lock ring over the cable ties.The second launch was at 40 psi. Straight and true to about 150 feet. The nose cone stayed on and the rocket nosed in!
I popped the dents out of the nose section. These PET bottles are tough!
The fourth try was like the first, the rocket popped off the launcher on the first pump. From now on I'll have to double check the cable tie release before using the air pump.
The fifth launch was perfect!
45 psi got the rocket up fast to about 200'. At apogee the nose cone fell off and the parachute opened - Success! This was how they should recover.
Water rockets leave the launcher very fast and decelerate to almost a standstill at apogee. They seem to hang in place before coming down.
Three girls were kicking around a soccer ball asked about the rocket.
They were surprised by how high it flew and how simple the launch mechanism was. It was nice to have some success in front of a small audience.
www.aircommandrockets.com describes the recovery method I tried as:
N.O.A.A. or Nosecone - Off - At - Apogee.
"A parachute deployment technique where the nosecone is suppose to fall off as the rocket reaches apogee allowing the parachute to fall out".
This deployment looks to be reliable, simple and effective:
Squashed Balloon Parachute Deployment
http://www.h2orocket.com/topic/balloon/balloon.html
love reading about your launches!
ReplyDeleteThanks Simon!
DeleteI had an email once where somebody wrote:
"Quit the launch reports and stick to building!"
My response was something to the extent of:
"It's a blog record of my rocketry experiences. You are free to start your own blog about your builds."
His blog lasted two posts!
I thought a report on the water rockets would be a interesting change.
Nice Work Chris. Glad to hear you had some good launches! But one word of warning water rockets can be highly addictive! You'll never walk through the supermarket again without looking at all the soda bottles and their aerodynamic properties. :) Also not all bottles are created equal, use only those for carbonated drinks. The ones with unpressurised contents are generally weaker.
ReplyDeleteWith the NOAA deployment we found it took a few flights to get it dialed in for a particular rocket, but it was still perhaps only 60-70% effective. Early or late deploys were very common.
Best of luck with future developments!
Thanks George!
DeleteWater rockets were a big surprise. Thanks for the tip about carbonated drink bottles, I didn't know that. I know a bottle can be pressurized to 120 PSI, but for right now I'm only at 40 PSI.
It did take me a few flights and some trimming of the "cap" to get the NOAA to work.
I'll be trying the balloon deployment soon.