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Nature of the beast or bugs to work out?

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LaunchPad

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I've finally gotten around to launching my rockets on a more regular basis lately and launch 3-4 when I go out.
However, it seems like at least one is not always doing what it should.

For example, a couple of them have acted line ground to ground missiles. Instead of going straight up, they curved or went in an arch. These were Alphas and I tried stronger yet recommended engines in them.
Others don't go as high or when they do go up, they come down a lot farther away.
I suppose drifting with the wind is part of the landing process?

And even though it is adjustable, should I have the launch rod always straight up or would I ever have it leaning against the wind?
I think that has been one of the problems. That it somehow isn't always straight up.
 

rharshberger

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I've finally gotten around to launching my rockets on a more regular basis lately and launch 3-4 when I go out.
However, it seems like at least one is not always doing what it should.

For example, a couple of them have acted line ground to ground missiles. Instead of going straight up, they curved or went in an arch. These were Alphas and I tried stronger yet recommended engines in them.
Others don't go as high or when they do go up, they come down a lot farther away.
I suppose drifting with the wind is part of the landing process?

And even though it is adjustable, should I have the launch rod always straight up or would I ever have it leaning against the wind?
I think that has been one of the problems. That it somehow isn't always straight up.
Models that are stable to begin with will turn INTO the wind ( weathercock) the more stable the more weathercocking. Angling the launch rod down wind slightly will allow over stable models to weathercock to a more vertical flight position.
The length of the delay can allow the rocket to coast into a arcing trajectory. To long a delay and the rocket can even smash into the ground, too short of a delay and the body tube can be damaged. The goal with the delay is to time it so the rocket has coasted to the very top of it trajectory and pop the chute there.

If your local library has it the Handbook of Model Rocketry by G. Harry Stine is a book every rocketeer needs to read at least once.
 
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MCriscione

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Weathercocking is certainly a possibility and it can be fairly extreme depending on wind condition and the rocket's stability. However, if the rocket is arching over and heading back towards the ground while still under power, that would be a larger concern. If that's happening then it's almost certainly that you've got some misaligned fins. I'd say you could be overweight for the engine side, but given it's an Alpha and it sounds like you're not launching it on 1/2As, you're probably fine there.
 

LaunchPad

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Models that are stable to begin with will turn INTO the wind ( weathercock) the more stable the more weathercocking. Angling the launch rod down wind slightly will allow over stable models to weathercock to a more vertical flight position.
The length of the delay can allow the rocket to coast into a arcing trajectory. To long a delay and the rocket can even smash into the ground, too short of a delay and the body tube can be damaged. The goal with the delay is to time it so the rocket has coasted to the very top of it trajectory and pop the chute there.

If your local library has it the Handbook of Model Rocketry by G. Harry Stine is a book every rocketeer needs to read at least once.
What do you mean by "delay?"
Delay of what?
 

Zeus-cat

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The delay is the motor delay. For example a C6-5 has a 5 second delay AFTER motor burnout. So the actual delay in the motor is motor burn time plus five seconds. However, all we really care about is the 5 seconds as that is the coast phase of the rocket where aerodynamic drag slows the rocket down after the thrust phase has ended. If you have chosen the proper motor the rocket should slow down close to zero velocity (or so we hope) when the ejection charge goes off and deploys the parachute. If you use a C6-5 and the rocket has already peaked and is heading back down at a high speed switch to a C6-3 for the next launch. The 3 in the C6-3 indicates a 3 second delay after burnout.

Most Estes and Quest motors have several delays for the same basic motor, C6-3, C6-5 and C6-7 for example. They have 3, 5 and 7 second delays respectively. You want the one that gets you closest to the peak altitude for parachute ejection.
 
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rharshberger

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What do you mean by "delay?"
Delay of what?
The delay is between motor burn out and the ejection charge. As Zeus-Cat pointed out it allows a certain amount of coasting to allow the rocket to reach apogee and near zero velocity before the ejection charge fires. On windy days/or with heavy models it may be necessary to use a shorter delay.
 

LaunchPad

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The delay is the motor delay. For example a C6-5 has a 5 second delay AFTER motor burnout. So the actual delay in the motor is motor burn time plus five seconds. However, all we really care about is the 5 seconds as that is the coast phase of the rocket where aerodynamic drag slows the rocket down after the thrust phase has ended. If you have chosen the proper motor the rocket should slow down close to zero velocity (or so we hope) when the ejection charge goes off and deploys the parachute. If you use a C6-5 and the rocket has already peaked and is heading back down at a high speed switch to a C6-3 for the next launch. The 3 in the C6-3 indicates a 3 second delay after burnout.

Most Estes and Quest motors have several delays for the same basic motor, C6-3, C6-5 and C6-7 for example. They have 3, 5 and 7 second delays respectively. You want the one that gets you closest to the peak altitude for parachute ejection.
Hoo-Boy!

This seems to be getting more complicated than I wanted.
 

dhbarr

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So all of the things you mention are interrelated. But yes, going with recommended build techniques and motors is the simplest. Has to be virtually windless to match what it says on the box.

Maybe try changing one variable at a time?

HTH,
-dh.
 

LaunchPad

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What are you still confused about? I can try to explain it.
I dunno, I was always under the impression that all I had to do was follow the suggested engine sizes in the instructions.

Now it seems that I have to start making lists and charts when all I want to do is put the engine in and push the button.

And now it's suggested that on windy days or a bigger rocket use a shorter delay?

Just seems to be getting way too much to think about. How or what can I do to keep it simple to remember?
I don't wish to over think or over analyze this.

And I'm still not sure what the delay has to do with the rocket drifting or not coming back down closer to the launch site.
 

dhbarr

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Build as suggested, use recommended motors, and don't launch when there's more than a 5mph breeze. Nothing to memorize, nice & safe.
 

LaunchPad

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Build as suggested, use recommended motors, and don't launch when there's more than a 5mph breeze. Nothing to memorize, nice & safe.
I agree with that and I appreciate the simple advice and support.

I think it's going to be sometimes next to impossible to launch with little breeze in places with little trees which is the ideal place to launch.
But yeah, I'll try on less windy days.

Then why the other info that was given to me by the others?
It makes it overwhelming.
 

dhbarr

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I agree with that and I appreciate the simple advice and support.

I think it's going to be sometimes next to impossible to launch with little breeze in places with little trees which is the ideal place to launch.
But yeah, I'll try on less windy days.

Then why the other info that was given to me by the others?
It makes it overwhelming.
I think many of us default to wanting to try many different things, and maybe sometimes we assume others do as well.

There's lots of ways to enjoy the hobby, though!
 

AlfaBrewer

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Then why the other info that was given to me by the others?
It makes it overwhelming.
They were giving you an answer that gave more in-depth information. In your original post, you didn't specify you wanted to keep things as simple as possible.

The reason you have so much drift is wind. You can go to a smaller parachute, a streamer, or launch on less windy days.

Launching on days with as little wind as possible will help with both the arcing and the drift.
 

tomsteve

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on my estes rockets, imo some of them have pretty big chutes that will cause the light rocket to catch any small breeze and drift big time.
some of them- really light ones that have fins that don't extend past the bottom of the body tube- ill change out the chute and put on a streamer.
what I do is cut a dump hole in the chutes of rockets ( estes,quest, and similar rockets) to help decent rate speed up a bit.

one of the great things I love about rocketry is the trial and error. learning how what does what and what to do to change.
 

LaunchPad

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They were giving you an answer that gave more in-depth information. In your original post, you didn't specify you wanted to keep things as simple as possible.

The reason you have so much drift is wind. You can go to a smaller parachute, a streamer, or launch on less windy days.

Launching on days with as little wind as possible will help with both the arcing and the drift.
Today was much better with a lot less wind and making sure the launch rod was as straight as it could be helped the rockets not drift as far.
 

dhbarr

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Awesome! Hope you had some fun :)
 

LaunchPad

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Awesome! Hope you had some fun :)
Thank you.

I did even though I was only able to launch 3 out of 4.

This is what happened to the 4th one:

http://www.rocketryforum.com/showthread.php?135059-A-about-Estes-Express-or-large-rockets

And the engine in my Alpha got pushed up further in the body and the chute didn't deploy.
Oh well.
At least one of them didn't end up in the pond this time or another one end up lost in prairie weeds and get wet from rainstorms which is what has happened before.

I've given up on expecting perfection every time and just enjoying the ones that do what they are supposed to.
And they all came down very close to ground zero!
 

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