Rocket Fins?

[McKailas Dad]

Hello again!

I did post this question in the 'Welcome Desk', but thought it may be more appropriate to post it here...

Pics of what I am talking about below. (my prototype)

How can I make these fins more rigid? These will be going on an actual, powered rocket, so they will need to be as light and sturdy as possible.

Thanks for any and all suggestions!

[legion]

Add a cardboard/balsa/carbon fibre spar or two. Maybe a single cardboard strip that follows the inside of the fin edges.

[Miles Linnabery]

Dear Dad:
I suggest using a desoposable brush and 5min epoxy and coat the inside of the fin set with the opening pointed down on some wax paper to allow the extra to drip out. try different ways might try foam meat trays sanded to shape and glues into the inside.
Have fun experment,
MILES

[jleslie48]

If you really want stiff and light, try dribbling white pva (elmers) glue onto bathroom tissue, mush it up slightly so its damp tissue, with the glue permeated through the paper, and then sandwich/stuff your fin with it. Elmers is wonderful in that it wont expand. make sure its not too wet to soak your fin skin, but the tissue is wet enough so the tissue tacks onto the inside of the fin. when it dries, its really hard pack, and really light.

[Retired_for_now]

Given the way you've folded the skin of your fin, it should be pretty rigid as is (so long as you can glue it in place with those large tabs and keep the base wide). You can also laminate layers of card to build up a thinner fin (staggering the layers can build a tapered fin but I'm not sure that's needed). A laminated fin will be heavier than a hollow one. You can also build spars into the fin, either heavy card set in edge wise, folded box spars, or rolled cylinders.
Yogi

[cardist]

Try soaking them with a thin layer of superglue (cyano-acrylate). The structure looks rigid enough as observed by Yogi, so the ca will not add very much more weight and will toughen everything in the process.
All the best and happy modelling.
Bernie

[jleslie48]

Originally Posted by cardist

Try soaking them with a thin layer of superglue (cyano-acrylate). The structure looks rigid enough as observed by Yogi, so the ca will not add very much more weight and will toughen everything in the process.
All the best and happy modelling.
Bernie

I keep hearing the greatness of super-glue but where do you get it quantites besides those squeeze tubes, that are little more than 1-use tubes as they clog up in 10 seconds? And how do you keep from ruining the source container?

[SCEtoAUX]

Brush on Krazy Glue is good. There is even a glue that goes on purple and dries clear.
Krazy Glue | Products

The brush is attached to the lid. The lid screws on nice and tight so the glue does not dry out.

[cardist]

Originally Posted by jleslie48

I keep hearing the greatness of super-glue but where do you get it quantites besides those squeeze tubes, that are little more than 1-use tubes as they clog up in 10 seconds? And how do you keep from ruining the source container?

Don't forget that a little of this stuff goes a long way. I use cheap throw-away brushes to spread a small amount very quickly. I buy my super-glue from the Pound shop, £1 for a blister-pack of 6 tubes. Luvly-jubly.
B.

[sgoti]

Originally Posted by jleslie48

I keep hearing the greatness of super-glue but where do you get it quantites besides those squeeze tubes, that are little more than 1-use tubes as they clog up in 10 seconds? And how do you keep from ruining the source container?

Try the dealer locator page for Bob Smith Industries. What you are looking for is also know as CA, info page here.