The 18/20 case only has the the D13W and D21T (no E's) available with 4, 7, and 10 second delays, but yes, they are about $20 for a three-pack, and yes, the 18/20 case fits into a motor mount for a standard 18mm Estes A-C motor.
Moving up to a D motor.
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The 18/20 case only has the the D13W and D21T (no E's) available with 4, 7, and 10 second delays, but yes, they are about $20 for a three-pack, and yes, the 18/20 case fits into a motor mount for a standard 18mm Estes A-C motor.
I just did a quick price check at BMS: 18mm reloads are about $6 a pop ($18+ for a 3-pack). Estes D12s *list* for $12 for 2, so same price, but if you buy at Hobby Lobby they'll be somewhat less than that.
So in general, 18mm reload Ds are not saving you anything vs. 24mm BP Ds. They will of course get you different thrust curves and/or some additional total impulse. But not a way to save money.
Likewise, 24mm single-use composites cost more than discounted Estes E12s. But worth it.
RocketflierVB
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You can cluster them... I think it came out as a M3000ish
lakeroadster
When in doubt... build hell-for-stout!
FWIW... What I did on my Hammerhead was to size the motor mount for 29 mm, then made a simple removable adapter that will allow use of 24 mm also. If you stick with this concept as you build future rockets that adapter can be used on any rocket with a 29 mm mount.
That gives you a lot of motor options.
That gives you a lot of motor options.
That's good to know. At one point hobbylink sold a 3-pack of reloadable motor systems for a 18 a 24 + 29 I think at the time it was like 75 bucks? I wish I would have bought those when they were available. But I think having an 18 RMS wouldn't be such a bad idea. In fact where did you say you can pick one up at? Cuz I'm starting to fly more the smaller models you know your 24s I might even fly 18s it's just nice to have a variety. On the other hand I also have 29mm and 38mm rockets. I guess it just depends how much money I have in my wallet at the time. I think any size rocket whether you're flying an 18 or a 98 is fun.I just did a quick price check at BMS: 18mm reloads are about $6 a pop ($18+ for a 3-pack). Estes D12s *list* for $12 for 2, so same price, but if you buy at Hobby Lobby they'll be somewhat less than that.
So in general, 18mm reload Ds are not saving you anything vs. 24mm BP Ds. They will of course get you different thrust curves and/or some additional total impulse. But not a way to save money.
Likewise, 24mm single-use composites cost more than discounted Estes E12s. But worth it.
Holy smokes!!!! Wow!!! How many motors are there like a 100??
lakeroadster
When in doubt... build hell-for-stout!
About 300..
Nytrunner
Pop lugs, not drugs
288 it looks like. 4x42x clusters,+3x40x clusters
The other one looks like 7x44x clusters
RocketflierVB
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Yea, I saw this guy at LDRS in 2003, Argonia, I think. I asked him how he planned on igniting them all at once. He said he installs an aluminum foil flash pan, with a thin layer of BP, on each cluster with one igniter per flash pan. It was pretty impressive flight... I think it was about $1500 in motors though.
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That looks fine from here.
Note that the 10:1 ratio is a guideline but not any sort of hard and fast rule.
Note that the 10:1 ratio is a guideline but not any sort of hard and fast rule.
Senior Space Cadet
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That is freaking awesome!
If you like that then go have a look at these threads:
https://www.rocketryforum.com/threads/boris-katan-flights-2017-clusters-3d-printing-fun.139352/https://www.rocketryforum.com/threads/boris-katan-flights-2016-clusters-3d-printing-fun.133752/https://www.rocketryforum.com/threads/boris-katan-flights-2015-clusters-are-fun.125017/
There are more but these should keep you busy for a while.
rocketgeek101
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That is glorious!
GlenP
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A couple of suggestions to help you find the rocket on the way down, if you lose sight of it in the clouds.
Use a Jolly Logic chute release, this holds the chute closed with a rubber band until the rocket reaches a lower altitude, so it won't pop open above the cloud layer and drift farther away out of sight.
Try rigging up a personal keychain alarm so it pulls the pin and sounds an alarm at ejection, these are sometimes called a screamer. You might be able to hear it and find it easier in tall grass when it is screaming at you.
"Bird repellent" reflective mylar tape as a streamer, but your rocket will probably be too heavy and will need a chute, so maybe you can rig up a strip of this some how to not interfere with the chute, the reflections make it much easier to see on the way down.
A little talcum power, not too much, a light dusting of the chute helps it not stick to itself and makes a small cloud when the chute pops open, sometimes visible from the ground.
Your design looks good. I usually look at the specs of other kit rockets in terms of weight, length, dia, engine power, to make sure a kit bash or scratch build is within reasonable limits. Stability is pretty easy to get right, but when you are big and heavy, adding a little nose weight might eat up your margin for speed at the end of the rod. So, a slightly longer tube will increase your moment arm, requiring less nose weight to achieve stability. An oversimplification of the speed at the end of the rod is to make sure your peak thrust (available from thrust curve plots) within the first fraction of second while the rocket is still on the rod is some multiple of the total rocket weight, like 20, for example. But with the OpenRocket you can investigate the launch rod speed much more accurately. In some cases a 6 foot rod may make a big difference compared to a 3 or 4 foot rod, especially on a slighty breezy day. Sounds like you are having fun on your journey of discovery, good luck!
Use a Jolly Logic chute release, this holds the chute closed with a rubber band until the rocket reaches a lower altitude, so it won't pop open above the cloud layer and drift farther away out of sight.
Try rigging up a personal keychain alarm so it pulls the pin and sounds an alarm at ejection, these are sometimes called a screamer. You might be able to hear it and find it easier in tall grass when it is screaming at you.
"Bird repellent" reflective mylar tape as a streamer, but your rocket will probably be too heavy and will need a chute, so maybe you can rig up a strip of this some how to not interfere with the chute, the reflections make it much easier to see on the way down.
A little talcum power, not too much, a light dusting of the chute helps it not stick to itself and makes a small cloud when the chute pops open, sometimes visible from the ground.
Your design looks good. I usually look at the specs of other kit rockets in terms of weight, length, dia, engine power, to make sure a kit bash or scratch build is within reasonable limits. Stability is pretty easy to get right, but when you are big and heavy, adding a little nose weight might eat up your margin for speed at the end of the rod. So, a slightly longer tube will increase your moment arm, requiring less nose weight to achieve stability. An oversimplification of the speed at the end of the rod is to make sure your peak thrust (available from thrust curve plots) within the first fraction of second while the rocket is still on the rod is some multiple of the total rocket weight, like 20, for example. But with the OpenRocket you can investigate the launch rod speed much more accurately. In some cases a 6 foot rod may make a big difference compared to a 3 or 4 foot rod, especially on a slighty breezy day. Sounds like you are having fun on your journey of discovery, good luck!
That looks really good. Be aware that fins that go back past the airframe are more likely to break on landing. You can use a larger chute to slow the descent to mitigate this outcome. All part of being a rocketeer!
Remember if you are using balsa fins to keep the train parallel to the leading edge, for strength.
Remember if you are using balsa fins to keep the train parallel to the leading edge, for strength.
