Alt innom Rocketry

[esa]

Noe nytt anyone?

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I'm back from the NEAR meeting and NAMMO visit, which was very cool

 

I am also planning making another rocket motor, around a K-class with a 7-point star grain (for neutral burning) and maybe a new propellant we at NEAR are making. The size will be around 75 mm in width by 750 mm in length, and produce a lot of power

 

I will see how that goes...

 

esa

[varmit]

Ok, i stål eller?

Du får oppdatere oss med data om den,kansje eventuelt filmer?

[cyberPanda]

noen burde teste denne construksjonen i virkeligheten

[Republic3D]

Jeg kunne ikke vært mer enig, Panda.

[esa]

I had to do some calculations by hand, because I can't find a calc that has the 5-point star configuration. So here is a picture I have drawn of the grain structure and burn-rate. Every line should be equal in length, thus making the burn "neutral". Also, I have figured out that this motor is more like a M-class instead of a K-class

 

I have also figured out (by hand) that the Kn (burning surface area over area of nozzle throat) is around 130 for both the start of the burn and the end, also indicating a neutral burn profile. This picture shows the actual dimensions for my grain, 75 mm diameter, 20 mm diameter core with 12 mm slits, and a total length of 750 mm. Here is cross-section view of my grain structure / burning profile...

 

 

esa

[varmit]

well,how is it going?

[esa]

I have put the 75mm (inner diameter) rocket on hold, just TOO big at this moment. Another reason why is because that 7-point star grain configuration and the "new" propellant being devoloped at NEAR, is still in testing. I am putting the 75mm rocket on hold until things are all checked out...

 

So instead, I am building a 50mm (inner diameter) rocket motor now, which is still pretty big I will use KN/SB propellant with a Bates grain configuration. I have already got the casing (which is 6082-T6 aluminium), just need to grind down the wall thickness and length. I also have 303 stainless steel chunks for a nozzle (same type I used for my previous motor), and some aluminium for the bulkhead (I think I will make the bulkhead in aluminium this time, to save weight). I still need to run some motorcalcs to get the right dimensions, make some drawings and actually start to make it on the lathe (but I STILL don't have that much experience with the lathe yet). So far the progress is going great

 

I'm also figuring out how to make the airframe, parachutes, ejection system, fins, nosecone, etc. for my [A-100M] SRM I made not to long ago for Pioneer. I will post up some of my progress when I have some more time

 

Anything new with other's rocket projects (if there is any)?

 

esa

[varmit]

Har jo planer om å bygge meg noen pvc-motorer til å begynne med,men har ikke blitt noe av.

Litt problem med dysa,noen som vet råd for det?

[halvork]

Litt problem med dysa,noen som vet råd for det?

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Sjekk min post på "forrige side". Forklarer både motor og dyse.

[varmit]

Ok,takk

 

Skal bli kjekt å prøve,må bare få tak i noe pvc rør,kjemikalier og noe dysemateriell.

Skal nok filme/ta bilde av fyringen,så kan jeg legge ut!

[esa]

Well here is how my Pioneer rocket will look like (hopefully)

 

Skjult tekst: (Marker innholdet i feltet for å se teksten):

 

I plan to make my own cardboard for the airframe, experiment with this liquid plastic to mould a nosecone, use sterdy wood for the fins, sailing cloth for the parachute, and am working on the ejection charge...

 

So there are some details with my Pioneer rocket, but I'm also making another SRM (50mm in inner diameter). So I am pretty busy at the moment, will post up some specs on the motor soon (just rechecking them)

 

esa

[omr]

Interresting.

I must admit I have been watching this project for a while.

 

Having read about KNSu motors at Nakkas site, I have tried a few motors made vith PVC pressurepipes, 32 mm OD.

Works well, but I am in the process of making a all-steel casing and nozzle on my lathe.

 

I also thought thas NEAR's site was down, happy to see that I was wrong.

 

And a question for esa: Where did you buy your sorbitol?

[esa]

Interresting.

I must admit I have been watching this project for a while.

 

Having read about KNSu motors at Nakkas site, I have tried a few motors made vith PVC pressurepipes, 32 mm OD.

Works well, but I am in the process of making a all-steel casing and nozzle on my lathe.

 

I also thought thas NEAR's site was down, happy to see that I was wrong.

 

And a question for esa: Where did you buy your sorbitol?

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I would like to hear your details with that on-going project, you can also find some info on this forum from my all-steel SRM. You can also ask me if your curious about something

 

I also thought NEAR's site was dead, but I just contacted one of the admins and it took off from there The site is already getting redone by a professional web-designer, so there will be a brand new NEAR site appearing in a few months If you are really interested in rocketry, just contact one of the admins. You don't have to JUST be interested in the motors, there is electronics, parachutes, and other various things that one can do in rocketry. However, I would presume if you have a big interest, you would be able to understand some of the discussions concerning rocketry (like thrust, impulse, etc). I don't think you would have much of a problem with that, one just has to have a big interest in rocketry then its fine

 

Oh, as for the sorbitol, well NEAR shipped me some free kilos of it (to get me started) I have "contacts" now, so I can get really whatever I need..

 

It is a diabetic sugar though, so you might be able to find it in some stores (but I've had no luck). Using sucrose is very hard, sorbitol (and dextrose for that matter) are much more easier to cast and overall safier

 

esa

[varmit]

Jeg er ikke helt orientert når det gjelder pulse og trust,så må lære meg litt om det.

Har sett noen filmer av større motorer,en god motor i m-n,hvor mange kg skyver en slik?

Skal også begynne med pvc-raketter, både testing på bakken og i raketter.

[omr]

Nothing fancy, really.

Just 32 mm OD PVC-pipe with a plaster of Paris cast La Valle nozzle. The tubing was the failure point, so I got hold of some pressuretube used in the foodindustry. A bit more costly, but overall fine.

 

In my wee start I had problems with casting the nozzle, had to make a few rod & rammers before I got it right. So I decided on a all-steel motor, and up till now I hawe refined my lathe skills doing tools for smaller BP motors as a side project. Fun as well.

 

My thoughts are to make a timer for the recovery unit, and it starts with the ignition as an outside impulse, the impulse triggers the timer , and it again triggers the ejection charge after a set timedelay. I am sure you follow me.

 

As for the mathematics in this business, it's mainly Greek to me, but I am good at building and machinery.

 

And I have only tried KNSu, have a half kilo of dextrose I am goint to try some day.

[varmit]

Mhm,good.

Jeg skal vente litt med å bygge motor av stål,men skal prøve meg litt på PVC.

Fant en oppskrift her,kansje litt enkel? :oppskrift.

Har tenkt å lage meg noen motor-kropper som er klare til påfylling før jeg får kjøpt kjemikaliene,så jeg får lage noen PVC raketter som det bare er å fylle på.

 

Men,lønner det seg å lage en form til å smelte i brennstoffet som i linken min,med stang til hul kjerne osv? Eller bare fylle rett i raketten?

Og til dysa,kan ban bruke en epoxsy-leire fra biltema*?(de har forskjellige varianter)

 

 

*epoxy leire,søk i søkerruten på varenummer 36-1301. biltema

[esa]

omr,

 

Right now I'm struggling to find a timer, I'm thinking of buying one or getting someone to make me one. Electronics is pretty "Greek" to me Here is a page with instructions on how to build a timer, Deployment Timer

 

Practical experience is just as good as theoretical, whatever works best I myself like to consentrate on the rockets propulsion, which is my main interest. Construction is fun too, but once I get into the electronics, I'm pretty much lost

 

Once you try dextrose, you won't go back to sucrose Sucrose is hard, especially because you don't want the propellant to caramalize (which SU does easy). If it is not a big problem, then go for it, but it is the fastest burning sugar propellant and more prone to CATO. When making motors out of metal, do you use a motorcalc or something similar? Nakka has a really good motorcalc, and a casing calc to determind the optimal dimensions for your casing.

 

Also, post up some pictures of your rocket motors, pictures speak a thousand words Maybe you might be able to help varmit with his PVC motor? I don't have any experience in that section...

 

varmit,

 

Just follow a PVC motor design that you think is simple, that is the best and easiest way to start. I can't give you much advice, except when you are melting (casting) your propellant, always be prepared for the worst case scenario! Same thing goes when doing a test-fire, be prepared in case the whole thing explodes

 

Maybe omr can give you some advice with materials one can get in Norway? I'm not sure, but just give me some details on how much propellant you plan to have (in weight) and the burning surface area and nozzle throat area (for the Kn). This might not be so clear now, but let me know your progress

 

By the way, that link you posted on how to build a PVC motor looks fine to me. Here is a video on how to melt/cast your propellant Scott Fintel (just click on "Click Here" at the end of the first paragraph). I believe it will be very helpful

 

esa

[varmit]

Oh,muchos grasias!

 

I will load up pictues on my way,and I will take video when I send it up.

I don't know how much propellant I am going to use, but I will after some small motors make a G or H motor in PVC, but I don't want something advanced,but easy to make.

I think that the only thing I need is a PVC pipe, something to make a nozzle with,propellant and some more details.

I'l try with normal sugar in my smaller engines,and go for more usable sugar in my bigger ones.

 

And yes,I will sit 25 meters away with a electric igniter,and I will be behind a protction, so I or nobody else would be hurt,I promise!

And I will have a lot of kno3,so my plans are to fill a motor wih maybe up to 5-8 liters with propellant, and calkulate the nozzle out of that.

I will fire it many miles away from people, and I will leave a camera maybe 20 meters away,I'l be 300 meters + away,so nothing will or can go wrong. And when I melt the propellant,I will melt a little every time many times.

But I am going to wait a little with that one

[esa]

5-8 liters? That is a quite a bit, but always measure in weight, not volume

 

By the way, more fuel doesn't necessarly mean more "thrust", if that is what you are after. It all depends on what you want to acheive with your rocket, like a certain altitude or speed, a long burn neutral burn or maybe a fast regressive burn. You see the different classes on the list I sent you? It is measured in Total Impulse. A rocket can produce very low thrust (even not enough thrust to go anywhere), and can have the exact same total impulse as that of a high thrust one could. Weight is also an issue, because you can make a really big motor, but not be able to generate enough thrust to lift it off the ground. Adding more fuel can acheive multiple things, it also depends on the burning surface, type of propellant, weight, aerodynamical drag, nozzle specs, etc...

 

It is always nice to hear plans of the future, but concentrate on making this motor first. Make something as close as possible to a simple design you have found. Just getting the whole thing to work right is more then enough. Plus, you will love the sound the rocket motor makes

 

esa

[varmit]

He he yes,that big motor would be fiered on the ground,but I am going to wait with that.

The meaning with it is to push hard,and I will calkulate the nozzle and place it in something witch I can read off the power.

And,do they make a big sound?

 

I will read a bit about rocketry,and later make a motor out of steel.

That motor the man on the video had,how powerfull was that?

 

And,one more thing:How do you messure rocket power?

I have heard of:

 

-Newton

-Pulse

-kg

-trust?