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/diy/ - Do It Yourself

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File: 19 KB, 709x532, rktparts[1].gif [View same] [iqdb] [saucenao] [google]
445608 No.445608 [Reply] [Original]

Aight /diy/kes

I wanna get back into model rocketry this summer to get my kíd into aerospace. SInce I was twelve, I've been making Estes model rockets, and always found them a little lackluster, so I want to DIY these rockets.

I wanna run my ideas so far by /diy/ to see what I'm missing.

DISCLAIMER: I don't really know how /diy/ would react to me asking about the chemical composition of fuel, igniters, etc., so I'm not going to ask. I'm pretty much set on that stuff anyway - gonna use some real basic rocket candy, and I'll modify the squib formula I've used in the past for igniters, so that's settled anyway.

So my plan is to use a paper towel tube that I'll reinforce by coating it with clear spray enamel (hope it's not flammable!... no I don't.) I'll use stabilizers made out of balsa wood. I'll sand off the enamel before gluing. The nose cone will be the top of a plastic egg. I'll just use some tissue paper for recovery wadding, and elastic for a shock cord. No parachute or any other recovery system for me. I'd rather rebuild a broken rocket than lose another in the trees. The motor will be solid fuel and cased in some 1" diameter PVC. It will have thrust, track, and recovery phases.

I'm going to custom build the controller to have a little more "zazz" that those yellow pieces of crap at the store. Key, switch, button, light, maybe some stickers for extra bad-assery?

No idea what to use for a guide rod tube, but I'm thinking I might buyfag a launchpad and guide rod, because those actually were pretty solid as I recal.

(Studied aeronautics for five years before switching to computer science, but do have a pilots license. Been flying for about fourteen years now. Soldering for even longer than that. Mixing dangerous chemicals for fun, but not profit, for about as long as soldering. Gonna to the dangerous parts in isolation, including launches until I'm sure my method is safe. Pretty sure I'm not gonna blow myself up doing this, but if I do... meh)

>> No.445629

Going full diy is cool but the whole point of the simple (boring) Estes kits is that little kids can do it by the selves for the most part. There is no reason not to move on to bigger, better stuff once you get youtalented /diy/erup to speed but really don't do it for him. Go buy a couple simple kits let him fuck them up and when he needs dad for help you will be there. After that you can start doing stuff that will get you and jr. on a watch list.

>> No.445637

you can get 99% ethanol at nearly every pharmacy. a quick google reveals a company by the name of oxy2go sells oxygen cartriges.

i'm sure you're familiar with vergeltungswaffe 1 and 2.

>> No.445639
File: 63 KB, 450x340, 1263214156536.jpg [View same] [iqdb] [saucenao] [google]
445639

>>445629
>pic related

>>445637
vergeltungswaffe 1 and 2.
Holy crap a buzz bomb would be awesome, but we're gonna start out small.

>> No.445640

i mean, sticking a "custom cardboard tube" on a stock engine isn't really diy, so I don't really get what the problem is, and don't understand the problems you're facing.

>> No.445643

>>445640
>stock engine
And where did you get that idea?

>> No.445641

>>445640
>I wanna run my ideas so far by /diy/ to see what I'm missing.

Maybe I'm not missing anything.

>> No.445644

>>445643
>gonna use some real basic rocket candy

>> No.445655

>>445644
Oh well that's my bad then. Just in case any one else thought I meant that I'm going to use Estes rockets, I mean that I'm going to take the ingredients for rocket candy, mix them in the correct ratio for the thrust phase (and a different ratio for the track phase), cook it down, pour it into the rocket motor case (the PVC pipe I mentioned), and, of course, shape the mixture as it solidifies so that the propellent will form a nice little combustion chamber.

My bad.

>> No.445675

Fun stuff.

Don't really worry to much about making the fuel. I have made some KNO3 rocket fuel before, and had the misfortune of having some ignite while I was cooking the mixture. My face was far enough away that I only suffered 1st degree burns to the side of my face, and some lightly singed hair.

It hurt like hell, but I was fine by that evening. Just keep your face away from the mixture, and don't heat it up too much. Then, even a catastrophic failure won't cause too much damage.

>> No.445685

>>445608
The thing with the pre-made engines is that the nozzle is rather difficult to make well.

It must be reasonably fire-resistant, very light weight and has to be shaped pretty precisely for the engine to develop thrust effectively.

>> No.445847

>>445608

If you studied aeronautics for 5 years you probably already know this but with model rocket building one of the most critical things is making sure that you have your center of pressure in the right location relative to your center of gravity.

This means that you need to balance your weight and your fin size properly. If you do not do this, there's a risk of the rocket being unstable and turning around or going off course. Estes rockets have already taken this into consideration that's why they work well.

There's a good book on this stuff called "The Model Rocket Handbook" which describes most of this in detail. It's less than $20 online.

You're also going to need to worry about the thrust per time produced by your engines since they are custom. You'll have to size them properly otherwise they won't have enough initial thrust for liftoff. I would suggest testing them on some sort of static test stand first.

I would also suggest this website: http://www.nakka-rocketry.net/

It has a lot of good rocketry info.

>> No.446062
File: 17 KB, 710x531, rktstabc[1].gif [View same] [iqdb] [saucenao] [google]
446062

>>445685
>The thing with the pre-made engines is that the nozzle is rather difficult to make well.
I, uh... wut?
I don't really know what you're trying to say here. First you say "pre-made", and then you talk about "making".
So, incase you didn't read the OP, there will be no pre-made engines. If you're just trying to give me a heads up on making an appropriate combustion chamber and nozzle, thanks.

>>445847
/diy/ has NOT let me down today!

Thanks Anon.

Good heads up on the cp/cg issue (pic related)

>I would suggest testing them on some sort of static test stand first.
Oh yeah baby I've looking forward to this part almost as much as shooting the thing off.


Pretty nice website too.

>> No.446085

This was the only thing I wasn't sure about, but I think I'll give this a shot.

http://youtu.be/0_mze6kZb94
>Rocket Engine Nozzle

>> No.446198

>>446085
I've had good experience with Durhams, it won't let you down.
Looking through this thread, there isn't anything missing that I can see. Look into the various guides that exist on making the sugar motors to be sure you haven't forgotten anything. Rocket design is piss easy with a bit of google-fu.

One warning, the kind of design you're talking about will be very rear-heavy. Also, tissue paper will catch fire. If you ask your local fire department very nicely, you can get some nomex cloth for free (you want pieces of their old shirts), which you can use as a fireproof streamer for stable and fast recovery.

So you know where I'm coming from:
Model rockets since I was 6, high power since I was 14.

>> No.446221

>>446198
That's cool. I've used tissue paper and toilet paper for years, and have never had any of it catch flame, but I'll remember you said that. Nomex ftw.

>> No.446227

>>446062
>I don't really know what you're trying to say here. First you say "pre-made", and then you talk about "making". ...
What I intended to say was that the nozzle dimensions are pretty critical for optimum performance.
The store-bought engines are tough to beat in terms of how much thrust they make for their size.

>> No.446380

>>445608
>So my plan is to use a paper towel tube that I'll reinforce by coating it with clear spray enamel (hope it's not flammable!... no I don't.)
it's flammable. Perhaps you could soak the tube in ammonium phosphate, which happens to be a fire retardent. Same for the wadding. You did say you had experience mixing dangerous chemicals after all?

Now if you're making rocket candy, why not make a better bigger rocket from fiberglass? If you design it right, you'll be able to break the sound barrier.

>> No.446383

get a small turbo from a car
make a small combustion chamber on the intake side and pump in oxygen and ethanol and ignite, you now have a turbopump

Attach the ethanol and oxygen to the exhaust side of the turbo so the pump can draw it out of the tanks faster, plumb output to a larger combustion chamber and ignite.

Congratulations, you now have a working Rocket engine. It will be horribly inefficient and have no thrust

>> No.446396
File: 122 KB, 1050x780, Untitled.jpg [View same] [iqdb] [saucenao] [google]
446396

>>446383
I drew a picture so you and your mongoloidtalented /diy/ercan figure it out

>> No.446397

>>446396
also i drew it wrong, the fuel from the tanks enters the compressor side and exits into the combustion chamber, I have it drawn on backwards