24mm MD

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Lister
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24mm MD

Postby Lister » Mon Nov 02, 2015 3:57 pm

Seeing as i found my 24mm MD prototype in the paddock and was able to salvage the nosecone i decided i would make a new one designed to break altitude records. it will be a thin wall FG tube and like with the 29mm MD i will be using 1.2mm CF for fins. im going with a 4 fin design for this rocket, im thinking of getting some 24mm fly away rail guides made up to reduce drag.

I have tinkered with the weight to find the weight that gives me the highest altitude, i plan on running D,E,F,G motors in this and should get some decent altitudes if not a record. im thinking of getting a stratologger for the altimeter as i wont be able to use motor eject for obvious reasons so im thinking a cable cutter or similar but i may just use a single chute or streamer as the cable cutters might be too big and heavy for this rocket... does anyone know of another altimeter that would fit in a 24mm rocket that i can use for dual deployment, and if there is any other method of dual deployment that would work in such a small rocket and not weigh a ton.
Attachments
24 MDRB 1.1.jpg
24 MDRB SvsT.jpg
Stability vs Time graph

Lister
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Re: 24mm MD

Postby Lister » Wed Nov 18, 2015 2:59 pm

After a short break from building rockets due to life getting in the way I have finally had time to get back in the shed.

Alot of scrounging produced a broomstick that was the right diameter for the 24mm tubes I needed to roll. After a few experiments with different cloth weight and number of wraps I settled on 2 layers of 287gsm with nuplex R180 epoxy resin which gave me a nice hard airframe at about .85mm thick and 300mm long.

The fins are 1mm thick woven CF with an airfoil on leading and teailing edges stuck on with JB weld and chopped CF.. am about to do the fillets on them but they seem pretty solid without them so im not worried about them shredding.

The nose cone isnt the one I will be flying it with, instead I will be using the 7:1Von Karmen thats coming with the 24mm MD that CJ hooked me up with.

I will also be machining my own 24mm tapered rear closure for it.

Thanks to the RAG Collective for the advice aswell as CJ for the advice and assistance re the other 24mm MD that will be a great rocket to test this against.
Attachments
2015-11-18 15.39.25.jpg
2015-11-18 15.39.25.jpg (218.97 KiB) Viewed 1756 times

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jase
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Re: 24mm MD

Postby jase » Wed Nov 18, 2015 3:27 pm

Good fun buddy 8)

Thank us when she flies!!!

Brings back memories, I built something similar once - flew really pretty on D12s but when I put an E9 in it :twisted: nearly killed the LCO (Howdy) :lol:

Renamed that one 'scribbler' :wink:

Your final fins look 'a little' different to the ones in the sim though...
Me and my rockets run on Moonshine.

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OverTheTop
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Re: 24mm MD

Postby OverTheTop » Wed Nov 18, 2015 3:31 pm

Looks great.

If you are going for altitude run a sim with a longer (say 5:1 or 7:1 von Karman) nosecone, if you can get one. You might be surprised how much extra altitude you can get.

Don't forget a nice polished paint surface if you are serious too :).
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Lister
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Re: 24mm MD

Postby Lister » Wed Nov 18, 2015 4:14 pm

Lmao jase. that doesnt surprise me. The fins I changed a bit just to get the stability better with the 7:1 nosecone which I hadnt done before.. I may even make another with the other fins to use with tbe ogive nose., these actually sim higher with the 7:1 nose I will be using.

Thanks OTT. The nose im getting from carolina composite rocketry is a 7:1. The sims say the ogive is actually better but from what I can gather a 5:1 - 7:1 vk will out perform the ogive in transonic range which is what this will be so the sims may not be telling the whole story.

As for the polished surfaces ive already got that planned.. any idea what paint/clear will give the best polished finish.. was even thinking of spraying a few light coats of epoxy on it through the airbrush could give a very high polished finish?

fins will be left as is because they are already like a mirror :)

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SpaceManMat
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Re: 24mm MD

Postby SpaceManMat » Wed Nov 18, 2015 5:16 pm

Clipped delta fins - nice. Already came to the conclusion that this is the way to go. What's your impression of working with carbon fibre? How much more difficult is it to sand? Especially the bevels?
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Lister
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Re: 24mm MD

Postby Lister » Wed Nov 18, 2015 6:21 pm

The only thing im a little concerned with is that the fin is only 1mm wide.. im hoping the fins dont flutter too much which is why another reason i went with these fins.. have you modeled the clipped delta fins, if so how did they go with flutter?

More difficult? Its probably as easy or easier than g10. If using a high speed cutter I wouldnt run it super fast as the CF conducts heat very bloody well as my finger tips found out. ... wear a mask when sanding/cutting or it will make super strength snot lol.

vance2loud
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Re: 24mm MD

Postby vance2loud » Wed Nov 18, 2015 6:57 pm

If possible try to cut carbon fibre wet. the dust particles can cause all kinds of health issues.
I use a fine hand saw for straight cuts and a hole saw in a drill press with cooling water for making centre rings.
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Lister
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Re: 24mm MD

Postby Lister » Wed Nov 18, 2015 7:25 pm

Yeah thats probably a good idea.. should do the same with any composite as they are all potentially dangerous.

I smoke like a chimney so I have that tar to protect my lungs from nasty particles :lol:

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OverTheTop
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Re: 24mm MD

Postby OverTheTop » Wed Nov 18, 2015 8:14 pm

For respiratory protection a couple of years back I got one of these:
http://solutions.3m.com.au/wps/portal/3 ... 802&rt=rud

I could wear it for hours whilst renovating, even on hot days. Surprisingly comfortable. Cost was $72 from a safety shop. Probably cheaper elsewhere.

Anyone who smokes needs to take extra care with particle inhalation. The lungs have greater trouble clearing the inhaled particles from the body.
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High Impulse
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Re: 24mm MD

Postby High Impulse » Wed Nov 18, 2015 8:27 pm

+1 with what OTT said, i've got a similar thing (different brand though) and works a charm. great for vacuuming even (especially if you have a dusty house...) or if you have excess amounts of arsenic or sulfur dioxide gas present in the atmosphere.
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Lister
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Re: 24mm MD

Postby Lister » Wed Nov 18, 2015 8:36 pm

Yes Dad :)

I do have a cartridge filter respirator I have for painting that I was using In winter but its too bloody hot in a 40° shed to wear the thing.. hows the 3m one go with fine particles?

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OverTheTop
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Re: 24mm MD

Postby OverTheTop » Thu Nov 19, 2015 6:25 am

hows the 3m one go with fine particles?

Quoting the 3M website:
"With a 3M 6000/7500 Series Half Face Respirator: for particles, for airborne concentrations up to 10 times the Workplace Exposure Standard (WES) "

You would need to delve into the relevant Australian standard to figure out what level they actually filter to. I was expecting them to have a particle size rating (similar to HEPA filters) but was disappointed.

I used it for a relatively serious reno. At the end of the day there was no need to have to pick rocks of snot out of my nose. Maybe I need to wear it when I go horse-riding :D Seemed to work really well on the reno.
Last edited by OverTheTop on Thu Nov 19, 2015 6:50 am, edited 1 time in total.
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Lister
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Re: 24mm MD

Postby Lister » Thu Nov 19, 2015 6:42 am

OverTheTop wrote:
hows the 3m one go with fine particles?

Quoting the 3M website:
"With a 3M 6000/7500 Series Half Face Respirator: for particles, for airborne concentrations up to 10 times the Workplace Exposure Standard (WES) "

You would need to delve into the relevant Australian standard to figure out what level they actually filter to. I was expecting them to have a particle size rating (similar to HEPA filters) but was disappointed.

I used it for a relatively serious reno. At the end of the day there was no need to have to pick rocks of snot out of my nose. Seemed to work really well.

Thanks Stew, ill look into them :)
Im guessing the reason the dont specify a particle size is down to varying pore size meaning, so they just give you a a general upto 10 times the WES.

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OverTheTop
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Re: 24mm MD

Postby OverTheTop » Thu Nov 19, 2015 6:46 am

I used a P2 filter. There is a P3 variant which I think is for better filtration. The full-face masks give better protection again.
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