Stick rocket launch tube angle

[Uarbor]

I have tried searching for this topic but I couldn't find anything. I live way out in the country and I have been launching my sugar Rockets basically straight up. So it depends on the Wind whereabouts Lake come down. I do have one neighbor and I don't want them coming down over there also there is a junkyard close my property on the other side. So I want to launch my rocket so they come down in my field. I was wondering if there is a particular angle that people used to reliably launch rockets so that they don't go straight up but also so that they don't end up horizontal because I intend to start putting headers on my rockets soon and I don't want them going off to low.

[Uarbor]

Anyway yesterday I tried about 11 degrees they started going toward where they're supposed to go and then after that they just went straight up anyway.

[Arthur]

The path of a rocket is very dependent on the mass and the mass distribution. A moderate rocket will vanish into the sky, but fit it with a 3" header then it may well burst far too low. Some tests are called for.

[MadMat]

I don't think you're going to find any "magic angle" that works all the time. Wind direction and speed are going to make that impossible. One thing to do that will help consistency is to make sure your rocket design is consistent. Keep records of you rocket designs... i.e. stick length and weight, header weight etc and how it influences the flight path.

[Uarbor]

Thanks for the help guys. I am going to see how it does with my dummy header first and then go from there. I am just starting to Mill my stars now so they won't be ready for weeks until they dry. Plus I still have to make black match boy am I glad I saved some Mill dust from my last batch of black powder. A bunch of testing sounds like a bunch of fun to me LOL feel like a kid again at the age of 50 Edited May 23, 2021 by Uarbor

[Arthur]

Start with a short time from burnout to burst, extend the time if it's still up there. Otherwise the header break tends to be a daisy cutter and upset everyone.

[Uarbor]

Start with a short time from burnout to burst, extend the time if it's still up there. Otherwise the header break tends to be a daisy cutter and upset everyone.

thanks I was doing some testing today with dummy report heads. My new batch of fuel is slower since I decided to actually measure the iron oxide. So I reduced the nozzle size and they are going way up there now. Still experimenting with delay

[ronmoper76]

Start with a short time from burnout to burst, extend the time if it's still up there. Otherwise the header break tends to be a daisy cutter and upset everyone.

I blackmatch ballshells right on top of motors.They fire instantly when the delay burns through and that's always worked well for me.

[SharkWhisperer]

Anyway yesterday I tried about 11 degrees they started going toward where they're supposed to go and then after that they just went straight up anyway.

Without getting too technical, rocket stability (whether finned or on a stick) depends on the relationship between two quantities, the center of gravity (CG) and the center of pressure (CP). The CG is simple to identify--it's just where your rocket balances on your fingertip. The CP is a different story. It's the balance point of air resistance when hit from the side at a 90-degree angle. If your rocket was held horizontal in front of a fan, the CP would be the point where neither the nose nor tail would move in that breeze. Think about a model rocket with big fins--the CP would be further back than one with small fins. With a stick, the calculations are even simpler. For a rocket to fly stably, you want the CP to be behind the CG. The farther behind the CP is, the more stable the rocket will be. Counterintuitively, there is such a thing as "too stable". A stable rocket will "weathercock", that is, it will point itself into any wind. Meaning, in a steady breeze, a stable rocket will tilt slightly into the wind, with the end result being that it ends up going straight up instead of at an angle. Even if you point it into the wind (angle your launch rod/tube so it points into the wind), a stable rocket will correct for this and go straight up (after it gets some speed up). A super long stick makes a very stable rocket. At some point, you're trading off stability with a lot of stick weight that your rocket needs to haul upwards, so there's a sweet spot. A clear example of the CG/CP relationship is with a short stick or no stick. If you pull the stick off of a bottle rocket, that thing's going to do cartwheels (repeated parabolas). The CP is ahead of the CG. You don't want this scenario in fireworking or in model rocketry.

Edited May 24, 2021 by SharkWhisperer

[SharkWhisperer]

I blackmatch ballshells right on top of motors.They fire instantly when the delay burns through and that's always worked well for me.

Glad you traded in the Visco crossmatching on your shells, yuk, yuk, yuk!!!

[Uarbor]

Without getting too technical, rocket stability (whether finned or on a stick) depends on the relationship between two quantities, the center of gravity (CG) and the center of pressure (CP). The CG is simple to identify--it's just where your rocket balances on your fingertip. The CP is a different story. It's the balance point of air resistance when hit from the side at a 90-degree angle. If your rocket was held horizontal in front of a fan, the CP would be the point where neither the nose nor tail would move in that breeze. Think about a model rocket with big fins--the CP would be further back than one with small fins. With a stick, the calculations are even simpler. For a rocket to fly stably, you want the CP to be behind the CG. The farther behind the CP is, the more stable the rocket will be. Counterintuitively, there is such a thing as "too stable". A stable rocket will "weathercock", that is, it will point itself into any wind. Meaning, in a steady breeze, a stable rocket will tilt slightly into the wind, with the end result being that it ends up going straight up instead of at an angle. Even if you point it into the wind (angle your launch rod/tube so it points into the wind), a stable rocket will correct for this and go straight up (after it gets some speed up). A super long stick makes a very stable rocket. At some point, you're trading off stability with a lot of stick weight that your rocket needs to haul upwards, so there's a sweet spot. A clear example of the CG/CP relationship is with a short stick or no stick. If you pull the stick off of a bottle rocket, that thing's going to do cartwheels (repeated parabolas). The CP is ahead of the CG. You don't want this scenario in fireworking or in model rocketry.

well this explains why using a shorter fatter stick did not work very well. I have a little Sawmill and I cut my own sticks on the table saw. I really like the idea of making everything myself I wouldn't mind learning to roll the tubes. There is something oddly satisfying about knowing that my Sticks came from an 18 inch thick poplar tree. We also have a lot of Japanese knotweed here which is a lot like bamboo only lighter. My first rocket used that very long and very light

[ronmoper76]

Glad you traded in the Visco crossmatching on your shells, yuk, yuk, yuk!!!

lol

[ronmoper76]

Without getting too technical, rocket stability (whether finned or on a stick) depends on the relationship between two quantities, the center of gravity (CG) and the center of pressure (CP). The CG is simple to identify--it's just where your rocket balances on your fingertip. The CP is a different story. It's the balance point of air resistance when hit from the side at a 90-degree angle. If your rocket was held horizontal in front of a fan, the CP would be the point where neither the nose nor tail would move in that breeze. Think about a model rocket with big fins--the CP would be further back than one with small fins. With a stick, the calculations are even simpler. For a rocket to fly stably, you want the CP to be behind the CG. The farther behind the CP is, the more stable the rocket will be. Counterintuitively, there is such a thing as "too stable". A stable rocket will "weathercock", that is, it will point itself into any wind. Meaning, in a steady breeze, a stable rocket will tilt slightly into the wind, with the end result being that it ends up going straight up instead of at an angle. Even if you point it into the wind (angle your launch rod/tube so it points into the wind), a stable rocket will correct for this and go straight up (after it gets some speed up). A super long stick makes a very stable rocket. At some point, you're trading off stability with a lot of stick weight that your rocket needs to haul upwards, so there's a sweet spot. A clear example of the CG/CP relationship is with a short stick or no stick. If you pull the stick off of a bottle rocket, that thing's going to do cartwheels (repeated parabolas). The CP is ahead of the CG. You don't want this scenario in fireworking or in model rocketry.

I had this issue 10 different ways,not nearly enough weight on heading,sticks to small or too flimsy"i snapped a dozen sticks in half this way",not using a launch tube long enough,center of gravity off from to short of a stick,stick becoming detached from motor at launch"really cool looking"heading not attached solidly enough and moving from the torc of launch steering it in other directions.

My first 25 rockets were wild out of control missiles and totally unpredictable. Then i read on this forum somewhere that if people spent more time on the details and there craftsmanship than quantity of work done the results would be that much better. I believe this as a very true statement. It wasn't how much of something i used necessarily,but how well i constructed it that gave me that smile and exceptional results. Ball shells were OK till i learned how to reinforce the hell out of one,the difference was night and day,it went from cool to wow i can't believe i built that! Even with flash powder,yeah it will perform in just about anything with enplugs,but take half as much flash and contain it twice as good and the difference is obvious.Sadly my personal experience has been that everything i learned how to do decently,i also learned how to screw up quite well beforehand. My best launches were completely vertical,a long enough launch tube to counteract the initial thrust curve,never just pushed in the dirt,and everything needs to be solid from end to end with your construction. I have a obsession with 3.00 rolls of discount strapping tape,it works on all kinds of things

Edited May 24, 2021 by ronmoper76

[Uarbor]

I had this issue 10 different ways,not nearly enough weight on heading,sticks to small or too flimsy"i snapped a dozen sticks in half this way",not using a launch tube long enough,center of gravity off from to short of a stick,stick becoming detached from motor at launch"really cool looking"heading not attached solidly enough and moving from the torc of launch steering it in other directions.

My first 25 rockets were wild out of control missiles and totally unpredictable. Then i read on this forum somewhere that if people spent more time on the details and there craftsmanship than quantity of work done the results would be that much better. I believe this as a very true statement. It wasn't how much of something i used necessarily,but how well i constructed it that gave me that smile and exceptional results. Ball shells were OK till i learned how to reinforce the hell out of one,the difference was night and day,it went from cool to wow i can't believe i built that! Even with flash powder,yeah it will perform in just about anything with enplugs,but take half as much flash and contain it twice as good and the difference is obvious.Sadly my personal experience has been that everything i learned how to do decently,i also learned how to screw up quite well beforehand. My best launches were completely vertical,a long enough launch tube to counteract the initial thrust curve,never just pushed in the dirt,and everything needs to be solid from end to end with your construction. I have a obsession with 3.00 rolls of discount strapping tape,it works on all kinds of things

strapping tape is getting hard to find. The post office doesn't want you to use it anymore. the dollar store doesn't carry it and Wally World only sells it in 2 in wide rolls.

[ronmoper76]

strapping tape is getting hard to find. The post office doesn't want you to use it anymore. the dollar store doesn't carry it and Wally World only sells it in 2 in wide r

we have surplus stores where i live that sell everything from nuts and bolts to fabric and foam to ax handles to plexiglass to bags of tannerite,try to find one of those places. The ones i find are the size of a roll of duct tape. walmart is a no go.

[BetICouldMake1]

I don't think the precise angle of the launch tube is too important. Not saying you can stick the thing in at 45 degrees, but a couple degrees in any direction won't make much of a difference. As others have said, the tube just get's the rocket going in the right direction, once it's in the air the flight can be thrown off by wind or poor stabilization. The idea launch angle depends somewhat on your goals for the rocket. For whistle or strobe rockets I go nearly vertical. I only want enough of an angle that the rocket doesn't fly back behind me, but it's pretty close to vertical. For a rocket with a header that I want oriented correctly I use a little more angle. Getting that orientation correct will depend on how long your delay is relative to both the angle and the header weight.

 

In terms of sticks I actually prefer shorter and fatter, but I use two per rocket and tie or tape the ends together. This makes a very rigid setup, plus you can use a shorter launch tube, and they're easier to transport and you don't have the issue of the rocket trying to "fly around" the stick, especially on higher power motors like whistle. Added bonus, if your stick have a curve to them simply attach them so they curve under the motor and when you tie the ends together it straightens everything out. Making sure your sticks are firmly attached is crucial. I like to glue and tape (gum tape) or tie them on. If you lose the stick at launch or it's loosely attached and gets pushed off center you will get an erratic flight--been there done that.

[ronmoper76]

I don't think the precise angle of the launch tube is too important. Not saying you can stick the thing in at 45 degrees, but a couple degrees in any direction won't make much of a difference. As others have said, the tube just get's the rocket going in the right direction, once it's in the air the flight can be thrown off by wind or poor stabilization. The idea launch angle depends somewhat on your goals for the rocket. For whistle or strobe rockets I go nearly vertical. I only want enough of an angle that the rocket doesn't fly back behind me, but it's pretty close to vertical. For a rocket with a header that I want oriented correctly I use a little more angle. Getting that orientation correct will depend on how long your delay is relative to both the angle and the header weight.

 

In terms of sticks I actually prefer shorter and fatter, but I use two per rocket and tie or tape the ends together. This makes a very rigid setup, plus you can use a shorter launch tube, and they're easier to transport and you don't have the issue of the rocket trying to "fly around" the stick, especially on higher power motors like whistle. Added bonus, if your stick have a curve to them simply attach them so they curve under the motor and when you tie the ends together it straightens everything out. Making sure your sticks are firmly attached is crucial. I like to glue and tape (gum tape) or tie them on. If you lose the stick at launch or it's loosely attached and gets pushed off center you will get an erratic flight--been there done that.

I saw this double stick setup you talk of on youtube,i never tried it. Everything you said makes complete sense and now i'm gonna have to try it. I hate when they fly like a helicopter because the stick snapped,and those damned bent ones that i gotta throw away,good stuff here.

[Arthur]

It's been said in the UK that square sticks are better than round sticks of the same length and weight, purportedly because of the effect of the corners.

[BetICouldMake1]

It's been said in the UK that square sticks are better than round sticks of the same length and weight, purportedly because of the effect of the corners.

 

I've heard this as well and suspect it's true because of drag. When people talk about putting sticks on rockets and balancing them they are almost always talking about the sticks balancing the weight of the rocket, but a big part of what they're doing is creating drag. If you needed to physically weight a rocket below the nozzle finned rockets wouldn't work, but they do because they create drag.

 

Honestly, for pyro rockets I think conversations about COG and COP are way overblow. For all his attention to detail TR doesn't bother balancing his rockets. He puts and stick on and flies them. If you're wildly off in one direction or another things won't work, sure. Don't go slapping a broom handle on your 1lb rocket. But the stick design is quite forgiving if you are even reasonably close to the ideal balance.

[Uarbor]

Thanks everyone for all the good information. I think I'm going to try the double stick thing.