33 replies to this topic

[Stuart]

The sticks are 3mm

Stuart

[pyromaniac303]

If what you are saying about the stick acting as a lever is correct, you could minimise weight by having a thin stick at the rocket end, and thicker towards the bottom. I might try this as I have a 1 x 1/2 mile field near my house, and try using a shorter stick.

I would only be using the teleflite fuel (63 KNO3, 27 Sugar, 10 Sulphur), as I dont have a ball mill to make good quality BP yet. I will let you know the results some time in the next week or two while I get time off college.

Has anyone got any thoughts before I try this? And do you think that using a tapered stick is dangerous? I will wait a couple of days before trying it incase somone comes up with any safety issues first.

[Jerronimo]

U don't need good quality BP for rockets if you make core-burning ones.
Simple greemmix (3 components just mixed together) is sufficient.

I wouldn't use the teleflight propellant as the sugar in it is hygroscopic.
Performance will drop considerably in a matter of days.
For sticks u can best use pinewood,cut into square sticks it's cheap and lightweight.

[Rip Rap]

Has anyone any info on rocket stick lengths? I was looking on google but keep finding contradicting info.
If I make a rocket more top heavy by adding a payload,do I need a longer stick? or more ballast?

There is so much about center of gravity,preasure and drag it seems confusing.
Should the stick be square section or round? Is it not to important? or is the stick just there to keep it upright till the tail end leaves the launch tube and the rocket gets up thrust?

I wouldnt fancy one nose diving where it shouldn't with a big payload on.

Hope some rocket guru can help!

From a previous post in this thead
link

For small (bottle) rockets, it doesn't matter whether the stick is round or square. I have read many times that especially for larger rockets, you should use square sticks. The largest I have made are 25mm id & have used both square & round sticks to stabilise them - there appeared to be no difference in flight stability.

After the stick has been added to a completed rocket (with any header attached) it should balance just behind the nozzle of the rocket.

[pyromaniac303]

Sorry about leaving this so long, but since my rockets are not that reliable I figured that I wouldnt be the best person to do a test on rocket stability using different stick types. And taking it to the point of not balancing is too risky so I abandoned the test all together. If anyone has any more information on tapered sticks being used to reduce the overall unnecesary weight I would be interested though, as it would hopefully increase the efficiency and the load capacity by a couple of grams.

[Maineiac]

From a previous post in this thead
link

After the stick has been added to a completed rocket (with any header attached) it should balance just behind the nozzle of the rocket.

Balancing just behind the motor is a bit of a fallacy. Try balancing a rocket motor that weighs 135 grams to which is attached a header weighing 350 grams. The stick needed would be rediculous in size and seriously detract from rocket performance. A typical 1# rocket uses no more than a .375" thick guide and they are generally no longer than 36". Typically ripped from Aspen boards. Only rockets 2oz. (.375" id) and under are ever balanced. To try the others is a waste of time and effort.
The main trick here is to use square sticks as previously mentioned and to shoot into the wind. The square form causes the rocket to weather-cock into said wind. This helps to keep the rocket where you want it.
And all this talk of ball milling rocket comp..... not required either. The above mentioned 135 gram motor is a mix of cheap mixed hadwood charcoal(33%), fine KNO3(58%) and sulphur(9%). Screened twice through a 40 mesh sieve is about all the incorporation you will ever need. Some of the more experienced rocketeers will recognize this formula. Can you argue with a Grand Masters success?

Good luck with all your rockets!

[maxman]

It seems that 24" to 28" is about right for what I suspect most people will be making on here. That is to say 8oz and 1lb rockets. Here is a link to a site I found selling sticks. I wish there were a UK based site selling some though http://www.mhtc.net/~mws/order.htm

[minalth]

I would imagine that when reducing the weight of the stick, flights similar to those used on arrows would help to balance the rocket.
The must be a reason why these aren't used commonly, but I can't see the reason why they wouldn't work.
Maybe they're just too much effort
if anyone knows a good reason why they wouldn't work please say

[pyromaniac303]

I would imagine that when reducing the weight of the stick, flights similar to those used on arrows would help to balance the rocket.
The must be a reason why these aren't used commonly, but I can't see the reason why they wouldn't work.
Maybe they're just too much effort
if anyone knows a good reason why they wouldn't work please say

Feathers act basically like the fins on a rocket, so I'm sure you could try them.

It is possible to use fins/feathers completely instead of sticks, but it is much more effort cutting out fins than gluing a stick to your rocket, and it also means that they cannot be flown out of the normal launch tube type arrangement. I looked into this and the rocket has to get to a certain speed before the fins help to stabilize it, which means that it has to be kept in a straight line while it gets to this speed for a safe launch.

I'm sure if you looked hard enough on the internet you will find a formula relating to what fin area and what velocity you will need to achieve stability, but in the end its simpler to use a stick unless your making a reusable rocket.

Also make sure you have a resonably large area of feathers otherwise your rocket will become unstable, but I think you would be wasting your time trying it.

Edited by pyromaniac303, 18 May 2006 - 09:01 PM.

[Karl]

I agree with pyromaniac303 on this one.

I fly model rockets and realize how much extra hassle it would be to use fins instead of a stick. You will need a 'Launch Pad' like the ones you get with Ready To Fly rockets. This includes the pad, blast deflector and rod.
The Rocket has a 'Lug' on the side of it, kind of like a drinking straw. This is what the Rod goes inside, and guides the rocket up where hopefully it has achieved enough speed to stabilize itself.

On some ?Odd rocks?, I have got away with Cardboard fins, Duct-Taped on to the airframe. This could possibly be your best bet. Rather than gluing ect. Not to mention that it is economical.

[minalth]

I was thinking more along the lines of having cardboard or plastic fins on the end of a thin stick, maybe a kebab skewer thing.

I suppose if you did that though you would have to launch the rocket from a wide tube (enough to fit the whole rocket inside) which would have to be longer than the usual launch tube.




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the fins would weigh virtually nothing and the stick not much.

Because the fins are at the end of the stake they would have more effect because the stick is acting like a lever.


EDIT I have no idea why my text of drawing doesnt show, but it looks beautiful

Edited by minalth, 19 May 2006 - 12:22 PM.

[damocov]

A quick way of putting "feathers" on a stick would be to buy some rubber arrow fletchings and glue them on like you do to an arrow - not sure how many you'd need, but if you want an excuse to make loads ofrockets for experimental purposes I'm sure you could have fun wiht a long term experiment

[minalth]

If you look at how rockets were invented it obvious that, although feather/fletches may work, balance sicks must be best to use.

This does not follow:P
the effort of procuring feathers and glueing them onto sticks with glues that would probably take days to dry and would certainly take time to make and get ingredients for, only for the feathers to burn up in mid-flight would be very different from the effort of cutting up some margerine tub lids that wouldnt burn and sticking them on with superglue...

not saying that they would necessarily be a good idea, but may be worth a try

[littlejohny]

I don't do many rockets, but I have gotten away with having small guide sticks by just grabbing a sheet of toilet paper folding as you would filter paper and taping it to the end of the stick and ruffling it a bit, the idea is to create more drag than stability, letting it fly straight. A feather taped on the end also works, but not as well. Another idea is a paper cone, which I think would be very successful. Sounds like a fair bit of work cutting out fins and gluing them on. Buying arrow fins would be very expensive they cost about $AUD0.80 that?s about $2.40 a rocket.