- This topic has 11 replies, 6 voices, and was last updated 17 years, 10 months ago by
mule.
mule.-
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SCOTT EVANS
So whats the maximum number of stages launched?????
I bought this Nomad (Flis Kit) Built and Launched it in september with the Cub Scouts. I lost the second stage, just like the Comanche I flew at the november launch.
I went down to the store today to buy the parts, to rebuild the second stage. And after looking at the prices, I decided that buying the whole kit again for 23 bucks, would be eisier and cheaper. (You know what I like about these little Rockets is that they are TV Rockets. Watch TV while building with the family instead of being in the garage!) Anyway I decided to put the 2 together and build a 5 or 6 foot (didnt really measure it) 4 stage Nomad. 2 D-12s followed by 2 C-6s. Has any one done 5 stages?Scott e
Ps Its all of you guys falt I wrote about this, cause you are all to quiet! 😉
Bruce R. Schaefer
Scott, it’s all about having enough thrust at each stage and continued stability. Remember your center of pressure (CP) must be at least one body tube diameter below the center of gravity. Okay, we all know that. Sim the rocket, find the CP, and check where the CG goes after each stage. I’ve never simmed a staged rocket. Hmmm… the CP is a normally static (doesn’t change) measurement, but when you drop a stage, you’ve just changed CP due to a sudden re-design of the rocket body. Sounds like a fun evening on RockSim. 😉 May take some nose weight. Most I’ve ever done is three. Unless you do the sim and calculations (yeah, the math) up front, spectators may be dodging stages flying across the prairie! You’ll achieve greater stability as it goes up amd drops stages (CG will move toward the nose), but if she’s horizontal after the first stage, kinda irrelevant. 😯
Doug Gerrard
Has any one done 5 stages?
Yes. I saw a tiny model rocket that flew four stages of A10’s each and then an A3 I think. All I remember was, Pop, Pop, Pop, Pop, and Whoosh. Kind of cute actually.
Doug
SCOTT EVANS
Scott, it’s all about having enough thrust at each stage and continued stability. Remember your center of pressure (CP) must be at least one body tube diameter below the center of gravity. Okay, we all know that. Sim the rocket, find the CP, and check where the CG goes after each stage. I’ve never simmed a staged rocket. Hmmm… the CP is a normally static (doesn’t change) measurement, but when you drop a stage, you’ve just changed CP due to a sudden re-design of the rocket body. Sounds like a fun evening on RockSim. 😉 May take some nose weight. Most I’ve ever done is three. Unless you do the sim and calculations (yeah, the math) up front, spectators may be dodging stages flying across the prairie! You’ll achieve greater stability as it goes up amd drops stages (CG will move toward the nose), but if she’s horizontal after the first stage, kinda irrelevant. 😯
Bruce
Rock sim will only do 3 stages I think. I will check it out the best I can. I think it will be ok though as I am just adding 1 stage and doubling the length of the Rocket. I think it will still weigh a lot less than that Saturn V I built as a kid and with a lot more fin area too. That Saturn Rocket with a “D” came off the pad like a Fat Man climbing a ladder. 8)Scott e
Bret Packard
Doug – If you ever call one of my projects “cute”, I may have to retire from rocketry 😛
The problem I see with doing more and more stages the same as concerns I have when I plan for longburners. If that rocket doesn’t go dead straight, by the 3rd, 4th or even 5th stage you have no idea where or what it will be headed at.
Doug Gerrard
Absolutely, the flight I described before was traveling horizontal by the time the last stage went off. It was so small though, no harm, no foul, just cute.
Doug
SCOTT EVANS
So I spent a couple of hours on rock sim today. The sim says its stable, and thats with a 50% longer body. The rocket will wiegh in between 11-12 OZ. about 3.5-4 OZ. heavier with the 4th stage and extra 18″ of body tube on top. My question is, does an Estas “D-12” have enough push to lift a 12 OZ. rocket. Rocksim seemed to think so. Rocksim thought it was going to wiegh 17 Oz (its 11 or 12) and would fly fine. 🙄 D-12 max thrust is 6.7 LBS with an average of 2.3 what ever thats worth. Max thrust is in the first half second. Is there stronger 24mm moter out there that will light another stage, I couldnt find one. I think it will fly fine, in a calmer wind anyway.
D-12s burn for 1.65 seconds and C-6s burn for 1.86 seconds.
By my calculations (2-Ds and 2-Cs), if something went wrong, we would only have to be Running and Dodging for 7.02 seconds 😉SCOTT EVANS
Answered my own question!!! Found manufacturer recommended max lift off wieght for a D-12 is 396.2 grams (slightly under 14 OZ.)
GOOD TO GO!!!! 8)
new2hpr
I haven’t done it, but a SU composite booster should light a BP sustainer, but not the other way around.
SCOTT EVANS
I haven’t done it, but a SU composite booster should light a BP sustainer, but not the other way around.
But, can you get them without a delay?
I supose with a reloadable you could leave the delay element out and put in a little more powder? 🙄I thought about this after I wrote it. I was way off.
Im just Using estas “D”s 4 should do it.
SCOTT EVANS
Bruce R. Schaefer
Doug Gerrard
Bret Packard
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