Applied maths & engineering

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mollwollfumble
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Applied maths & engineering

Postby mollwollfumble » Mon Mar 02, 2015 4:49 am

Hi all,

I'm David A Paterson but my webname is mollwollfumble.
By training I have a degree in Applied Maths and a PhD in Engineering, specialising in aerodynamics.
By occupation, I'm a retired Research Scientist/Research Engineer from CSIRO.
My dominant interest is science of all types.

I became involved in the theoretical side of a Google X-prize team (landing a rover on the Moon) for a year a few years ago, mostly looking into orbits, engineered materials, rocket engines for outer space and spacecraft weight budget.

I started building rockets a year ago, working up through C, D, E, F, G, H. Like recent forum joiner Brett, I recently only qualified level 1 at the last Serpentine launch for 2014, and I even had to revert to a kit rocket for that. I have designs prepared for an I, J, K, L.

As a rocket BUILDER I'm pretty awful. I lack all the basic skills needed for accuracy: machining, assembly accuracy, painting, polishing, sanding, gluing, etc.

My design interest is in extreme altitude for minimum cost, starting with Goddard Optimization - which is the mathematical solution to the problem "what is the minimum-fuel design for a given change in altitude?" - and progressing through massive multistaging using a variant of rack rocket design. I've built and almost-successfully flown a nine-stage low-power rocket using a 3-D printed nosecone and carbon fibre rack rods and fins. My latest (tentative) design is an uncompromising seven stage that may have the potential to reach the top of the atmosphere 100 km altitude with a total motor cost of $371.

martymonsta
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Re: Applied maths & engineering

Postby martymonsta » Mon Mar 02, 2015 11:56 am

Hi David and welcome to the forum.

mollwollfumble wrote:
My design interest is in extreme altitude for minimum cost, starting with Goddard Optimization - which is the mathematical solution to the problem "what is the minimum-fuel design for a given change in altitude?" - and progressing through massive multistaging using a variant of rack rocket design. I've built and almost-successfully flown a nine-stage low-power rocket using a 3-D printed nosecone and carbon fibre rack rods and fins. My latest (tentative) design is an uncompromising seven stage that may have the potential to reach the top of the atmosphere 100 km altitude with a total motor cost of $371.


I read this, this morning as a was running out the door to work. Wow I'm interested. I'd love to see how this works. What is the total impulse of all the motors? Do you have pictures? Are you coming to thunda?

Marty
Many years ago the great British explorer George Mallory, who was to die on Mount Everest, was asked why did he want to climb it. He said, "Because it is there."
Well, space is there, and we're going to climb it

MARS #21
AMRS #41 L2/LCO/RSO/CO

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jase
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Re: Applied maths & engineering

Postby jase » Mon Mar 02, 2015 12:49 pm

Yes, welcome to the forum.

Have you read Boris Garfinkel's work?

Link to abstract here: http://oai.dtic.mil/oai/oai?verb=getRec ... =AD0409855

There is a linked .pdf there that you can click on and read.

"massive multi-staging" is fine in theory and assuming; no gravity, no atmosphere, zero AoA etc...

Given that any terrestrial based launch will be subjected to; gravity, atmosphere and increasing AoA (Garfinkel refers to that as 'coasting arcs') for each motor start, you will be severely limited, ie: to a finite amount of motors.

My guess is that after your fourth or maybe even fifth motor ignites, the rocket will be on or very near a powered vertical descent flight profile given the presence of; gravity and atmosphere...

Anyway, have a read of the article I'm referring to above and let us know what you think.
Me and my rockets run on Moonshine.

october sky
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Re: Applied maths & engineering

Postby october sky » Mon Mar 02, 2015 12:53 pm

Hi David and welcome to the forum ! :D

You sure have an interesting back ground and very interesting concept there...wow :shock:

Keep all of us informed please.

In about a week this forum will be fairly quiet due to a big launch taking place at Westmar as of 12th of March till the 15th. I hope you could make it there even for a day or two. It will be huge !! 8)

Ari
QRS Inc. NO: 003

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TRA #11616 L3

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CATO
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Re: Applied maths & engineering

Postby CATO » Tue Mar 03, 2015 5:06 pm

Hi David and welcome to the forum.
"In thrust we trust"

AMRS 21 L3
TRA 07459 L3

Impulse:
2018: 14,767 Ns (44% N)
Ns 17: 5,973; 16: 34,558; 15: 35,955; 14: 6,016; 13: 10,208
PB - Gorilla N2717WC, H: 10,260', S: 1.14M

ogivemeahome
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Re: Applied maths & engineering

Postby ogivemeahome » Thu Mar 05, 2015 9:48 am

october sky wrote:... Keep all of us informed please. ...

What he said! :)
I haven't had much time for rocketry lately but the interest is still there.
I have the practical skills, but lack the education for more advanced pursuits.
Lots of collective experience on this forum - you need only ask. :wink:
A smooth sea never made a skilled mariner. (English Proverb)


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