Quote:
Originally Posted by cdavenport
The next big issue is deploying the chute in time to prevent the rocket from crashing. Having flown rockets, this can be a challenging problem for low altitude flights.
the flights you have filmed thus far indicate that the center of pressure is located near the center of gravity of your rockets, meaning weight is relatively evenly distributed along the rocket body. This is why your rockets are not following a ballistic trajectory once they run out of "juice."
Since they fall pretty much horizontally, just releasing the capsule will cause it to fall away quickly once the rocket starts falling. I would suggest you keep the capsule attached to the rocket body and have the parachute loosely packed under the capsule so that it unfurls quickly.
An excellent material to use is the plastic dry cleaners use to cover clothing items for pickup. It's very light. In addition, nylon string is very light, too, and readily available at any fabric store, Michaels, Hobby Lobby or Walmart. Hopefully you have one of those near you in AK.
BTW, enjoy the auroral displays that are going to be occurring. There's been a coronal mass ejection from the sun that should be hitting in the coming days.
Looking forward to a successful launch!
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Thanks for the heads up on the displays, however; not dark enough at night to see them. If you look at the pictures of the deployment system, in one of them you can see the front door to my apartment, notice how light the window is, that one was taken around 11:30 pm at night.
Using bead thread and elastic braid (1/8" wide) from the sewing department. Bead thread is nylon with three strands. Parachute is made out of a survival blanket (mylar) that is light and really strong.
Went on-line to find a chart showing how to correctly size the parachute for the rocket's weight. Drew up a hex pattern just like Estes uses for their rockets. Chute is 21" across.
Packs up small and is light weight.
The elastic braid is attached to the nosecone, parachute and fuselage. The nosecone should pull the chute out easily, as it falls free in the airstream.
Looks like it could rain today-no flight test yet. Tomorrow is supposed to be clear.
I've read on
The Rocketery Forum about using the dry cleaning bags. Went with the mylar blanket because we have them for sale where I work. Price was cheap with my discount. Work is where the springs and the fiber washers came from as well-cheap, cheap. Fiber washers work as load spreaders for the spring to hit with (rocket mount) as well as absorb the hit (nosecone mount).
Estes rockets would be in trouble with the CG and Center of pressure like you mention. It actually helps these rockets recover without damage. The Saturn V is a prime example of that! The Redstone however noses down at the last, demanding a parachute system.
Mike