Search found 100 matches

by camacd
Wed May 25, 2016 2:25 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

Are there any rules of thumb regarding the best shapes for fins to achieve stability and minimise risk of flutter? My instinct says to lengthen the base cord and shorten the height, but the sim often reduces stability when I increase the base. And also the height is clearly the most dominant dimensi...
by camacd
Wed May 25, 2016 11:21 am
Forum: News & Events
Topic: Samantha's Lucky 7 in the news
Replies: 7
Views: 1187

Re: Samantha's Lucky 7 in the news

Great coverage by ABC, and excellent role model for aspiring female scientists and engineers. Itsll not easy for girls in our profession.

With a PhD in chemistry, maybe we can have a rocket fuel manufacturer in OZ?!

Good luck for Lucky 7.
by camacd
Wed May 25, 2016 11:18 am
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

SO I have modified the fins to increase stability. They are quite a bit bigger than the original design - almost twice the surface area. Now the stability curve for the K1440 is showing minimum stability on the pad, then increasing before dropping back to approx cal 3.0. Perhaps I've gone a little t...
by camacd
Wed May 25, 2016 11:07 am
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

Thanks for that advice guys. I have not made the fins yet, so its not too late to make a significant change to the design to get the stability back. Up until now I have not been aware that the stability is so profoundly affected by the velocity. I'll do some more iterations on the design and hopeful...
by camacd
Tue May 24, 2016 9:09 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

You need to really watch your stability approaching Mach 2. Or can produce a graph of stability over the corse of the flight. Could you please post?


Ahhhh, the higher power motor is more stable at the start but drops to a very low stability at peak velocity.
by camacd
Tue May 24, 2016 9:01 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

You need to really watch your stability approaching Mach 2. Or can produce a graph of stability over the corse of the flight. Could you please post? Thanks for the advice Matt. I've plotted the worst case motor, and it seems OK for stability in my untrained eye. Minimum Cal about 1.35. I will do th...
by camacd
Tue May 24, 2016 4:26 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

So all the airframe sections are cut. Photo below shows everything that has been made so far. I've got exact weights for all the parts, and revised the design, and have subsequently tweaked the fins because for some reason it was showing as unstable in some configurations. So now the mass and the dr...
by camacd
Sat May 21, 2016 2:47 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

So tubes have been fibreglassed. I used peel ply, to get a better finish. For some reason I thought I should strip it when the resin was still green, but as I started to do this, it became quickly apparent that I was lifting the glass, so I had to work to ensure it was all sticking down properly and...
by camacd
Sat May 21, 2016 2:32 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

Part of your design consideration should be on how easy it is to move them to your other rockets. Good call. My AV skid looks positively spartan compared to yours, and it makes sense to modularise as much as possible. I won't change this design for now, but will devise an interchangeable module for...
by camacd
Fri May 20, 2016 9:58 am
Forum: Queensland Rocketry Society
Topic: QRS Workshops
Replies: 22
Views: 4532

Re: QRS Workshops

Any chance of running a workshop on electronics? I can deal with the gizmos if all I have to do is get them out of the box and turn them on, but I struggle with some of the terminology, and certainly when it comes to reprogramming etc, even simple things like getting them to communicate with my comp...
by camacd
Thu May 19, 2016 8:19 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

Some progress! I managed to satisfactorily test the BRB and so now the AV sled can progress in earnest. Unfortunately I only have one RRC3 altimeter, so I did a "brain transplant" from my L1 rocket into the L2. It took a little bit of farting around to get the LiPo battery mount right, but...
by camacd
Thu May 19, 2016 8:03 pm
Forum: Queensland Rocketry Society
Topic: QRS Workshops
Replies: 22
Views: 4532

Re: QRS Workshops

Damn, I have another commitment, but would love to do this workshop.

Hopefully will get more chances.
by camacd
Wed May 18, 2016 6:37 pm
Forum: Scratch Built
Topic: L2 build
Replies: 70
Views: 12982

Re: L2 build

Progress has stalled while I attended to some other life events (wife in hospital, son home from school withe a cough tat would kill a dog, and looking for a full time job), as well as prepping to fly David Bowie at the club day on Sunday. So now it is back to work on the project. (Wife still in hos...
by camacd
Sun May 15, 2016 5:04 pm
Forum: Queensland Rocketry Society
Topic: 15th May 2016 launch
Replies: 15
Views: 2893

Re: 15th May 2016 launch

My first flight of the day. VERY happy with this one. Pretty fast acceleration, and perfect deployment at exact calculated altitude within 20 feet. Landed about 200m away.

https://youtu.be/0KLTUxLB7fg
by camacd
Sun May 15, 2016 4:24 pm
Forum: Queensland Rocketry Society
Topic: 15th May 2016 launch
Replies: 15
Views: 2893

Re: 15th May 2016 launch

What great day! You would have to go a long way to find better conditions for rocketry than today. If a rocket launches exactly vertically to 4000 ft and then comes down on the parachute to within 10 metres of the launch rail, its pretty hard to beat. I'll post my humble iPhone videos of my flights ...

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