[johanngr]

johanngr

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After several simulations the rocket would appear to go to over 16km MSL.  Although this is good as far as altitude is concerned, it is not good for the venue and would place undue pressure on some of the pressure-based electronics.  Our aim is to break the 10km AGL altitude and as such I decided that having a slightly smaller rocket is in order.

A smaller rocket is easier to work with and will reduce costs by up to 30%.  As we gain experience we'll go bigger and higher.

I have done further analysis and so far the fins are about 560g each without the welding.  This means 1680g for the three fins.  They can be cut from a single 1m2 sheet of 3mm aluminium.

The rocket's overall length is 3.93m by 102mm.  A much better L/D than the 5.03m by 102mm!

[mark]

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• Water Bottle Rocketeer
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I would agree with that and even feel that a succesful flight to 9 km would be better than reaching 11 km but having something go wrong. So yes, keep it down to something achievable. There will still be lots of years to go even higher.

Anything close to 10 km sets up a whole lot of challenges.

This 102 mm sounds like the diameter of the rocket is set by the motor casing, which becomes the lower section?? Are the fins thus welded onto the casing? I think air drag plays a major role so this sounds sensible.What about coupling? Will the rocket likely go past Mach 1, in which case it has to be quite solid in all respects.

Is the challenge still to get a payload eiquivalent to a Coke can's weight up to that altitude?

Thanks for the update.

Mark

[johanngr]

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The challenge is not only a coke can to 10km but is seems 3 coke cans!  One for each Electronics team member.

The Rocket should reach Mach 2.5, so yes, it needs to be solid.

[Rian]

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I need the dimensions for the nosecone. I want to model an antenna design to fit on or inside the nosecone. Is my assumption correct that after drogue deployment the nosecone will be facing down?

[johanngr]

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Yes, it will be facing down but swinging on a tether.  The OD of the nosecone is 101.6mm.  It is 430mm long.  Do you need a cylinder of space inside or are you planning to make the antenna fit on the inside surface.  I still have to construct the nosecone mould afterwhich I can give you one to use for reference.  I should be finished in a week or two.

[Erik]

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• Water Bottle Rocketeer
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Hey Johann, any more thoughts on how the electronics are to be mounted? I was thinking sliding a cylinder inside the main outer cylinder might be another option.