22 replies to this topic

[Robert]

With regards to approval. The CAA have issued a NOTAM for launch from EARS in Cambridge.

[paul]

Robert, im no expert, but here is what I would try!

Is it not possible to fit a can of compressed air (like those used for blowing dust away from computers etc) in the payload to use as a oxidiser, which is then activated by a relay switch just before another battery deploys a charge to the nichrome or visco match ?

Too heavy, much too heavy I guess.


@ rr22: THANKS for the link! Not the page I had in my mind but even more interesting!

@ everyone pointing Robert to that CAA approval: Robert told us in his initial post that the "CAA approval is in place"...

Edited by paul, 04 November 2008 - 10:23 PM.

[Robert]

Too heavy, much too heavy I guess.


@ rr22: THANKS for the link! Not the page I had in my mind but even more interesting!

@ everyone pointing Robert to that CAA approval: Robert told us in his initial post that the "CAA approval is in place"...

Sorry I editied the first post to inculde it incase anyone else read it

[knackers]

perhaps using a nylon fishing line of appropriate strength for your payload lanyard would burn through easier than kite string then only needing a heating element of thin wire instead of a pyro comp, similar to an incandecent filiment, if the wire was wrapped around a few turns surely it would melt it, one would think

incandesent light bulbs need to function in a vacum or oxygen deficient enviroment, and if as said above the li-ion batterys will supply power in sub zero temps it should work

Edited by phill 63, 05 November 2008 - 08:09 AM.

[wjames]

id have thought that fishing line would be very very brittle at -40 degrees C ????

As a power kiter myself, i can tell you that 2mm Dyneema will take 220kg before it breaks.

and ive used it below zero - whilst sking....maybe -5.....with no effect on the cord at all.


Oh, and it melts easily too.

[knackers]

id have thought that fishing line would be very very brittle at -40 degrees C ????

As a power kiter myself, i can tell you that 2mm Dyneema will take 220kg before it breaks.

and ive used it below zero - whilst sking....maybe -5.....with no effect on the cord at all.


Oh, and it melts easily too.

5.1 Temperature Influence and Moisture Absorption

Nylon 12 has superior notched impact strength at low

temperatures. While nylon 6.6 and 6 (this is also due

to moisture conditioned specimens) embrittle at temperatures

of 0 to -20°C (+32 to -4°F), nylon 12 however resists high impact

even at -80°C (-112°F) as shown in graph 16.

At dry conditions, nylon 12 is more flexible than nylon 6.6

and remains more flexible over a broad temperature range

of -40 to 150°C (-40 to ~300°F).



Well i suppose it depends on which nylon you use and what you know about nylon,

[crystal palace fireworks]

[quote name='paul' date='Nov 4 2008, 10:19 PM' post='51138']
Too heavy, much too heavy I guess.

No surely not!,..............I can understand your point if it were a thick walled canister like a fire hydrant or butane gas bottle.

Perhaps an alternative is to fit a `non return valve` (drilled in to the sealed casing above the payload and then filled with compressed air is the answer!

[wjames]

some good data there phil - although do they acutally use nylon 12 in fishing lines ???? im asking as i don't know !