I'm building my first gap staged rocket out of two Baby Bertha kits. I'm worried that the lower stage tube will get worn out rather quickly after exposure to both the burnthrough on the booster motor and the ignition of the sustainer. Should I use some sort of inner lining? Any recommendations? (tin foil, etc.)
I've found that coating the joints / coupler, with CA works very well as a fire retardant.
If you're going 1 to 1 with your engines and don't use too much tape on the joints or make them too tight, the stages will separate quickly enough that singeing them won't be a problem but like most things, you'll have to get the feel for it as you go.
Well, I have about a 5 inch gap between the motors, so there is plenty of body tube exposed, a bit much to coat it all with CA. Creating a roll of tin foil that can be placed inside the tube, taped down, then replaced when nessicary was pretty easy, so i'm going to try it out on the first flight and see how it works.
I believe it is the Handbook of Model Rocketry that recommends simple liners made from typing (now printer) paper. Just cut them to size and replace frequently.
I wonder how many know what CARBON PAPER is?...lol
And on a related note...do Mechanical Engineering classes, these days, even teach the wonders of drawing with a classic drafting set, as we all learned? (I say this as I admire my old Dietzgen set, handed down to me by my Dad, many years ago...)
I just bought a lot of three off of eBay - a Pickett, a K&E, and an "unknown" brand, all in good working order, with cases. Amazingly, only 2 bids were made, including mine, and I got all 3 for $12.62, including shipping and tax. I'm looking forward to getting them -- a good slide rule is a very useful tool, and these look to be in great condition.
I plan to teach my nephews how to use them. I wish schools still taught slide rule use; using one makes things like keeping track of significant figures and estimating the order of magnitude of results in your head as a double-check automatic, and those are skills that are in very short supply these days.
Too many people take whatever number pops up in their calculator's display as gospel, regardless of how many decimal places it shows, or how far off from reality (due to a mistaken keypress) it obviously is. If they'd just double-check it in their heads for basic "sanity", they'd realize they made a mistake, and go back to fix it.
- Rick "Sorry for ranting on innumeracy; it's a pet peeve" Dickinson
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