staging BP motors

yesterday at a launch of a CC EXpress with a C11-0/C11-7, I noticed some massive tip-off from the sustainer..... There was NO WIND... The 2nd stage
ignition was low and close enough to see clearly...I went and picked up the booster and noticed that the booster motor had been , what I will describe as being "pulled" almost an inch upward. I attributed this to the fact that the two motors were taped together. It evidently must have taken some time and force to "break" this tape seal.
When you tape motors like this together, should you should "facilitate" the tape burnthru by taking a knife and slicing slots around the periphery of the motor junction?
Also it seems every staged model rocket I have ever seen seems to either weathercock, or the sustainer(s) fire and take off at some angle of attack to vertical, even in low or no wind conditions.
Is it even possible to get a straight up flight with a staged vehicle? I was thinking of making my boost with no fins, but the booster would be enclosed in a booster tube that extends up the sustainer, with 3 fins slots, so that the booster portion also actual as a launcher in the air..... the booster would have no fins.....the sustainer would have the fins.. what do you think?
tia
shockie B)
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the
that
Could be weight related, maybe move the cg forward just a bit or cloud have just been too much tape. Hard to say without seeing your prep. Pulled forward? Did the mount move too?

the
Shouldn't matter unless your using 6 - 7 feet of tape. ; )
You did use cello or masking tape, right? Not duct tape? ( Just joking )

Unless it left the rod absolutely perfectly straight the second stage seperation and power up kick, is going to continue any angle there was at liftoff. It's only micro seconds but the tape will not burn through evenly on all sides, there is always a point of first seperation and if it was heavily taped and took longer to burn through on the opposite sides, you may have had some micro vectoring from the side that burned through first. If the booster hung up a little it might have acted as a really bad fin.
A small amount of vectoring shouldn't matter once the 2nd stage is up to speed. There are a couple of photos at http://vernarockets.com/id3.html The photos about 2/3 way down the page listed as Dorothy, the side by side photos show a pretty straight liftoff with a momentary angle at 2nd stage ignition but once it was full up again, it corrected it's self and continued on fairly straight. This was a 3 to 3 cluster. Doing 1 to 1 should fly better and with less weather cocking. There could be other factors, see below.

Pretty close is not hard at all. Ram rod is another matter.
Some other things to consider: Could it have hung up any at all, even if only minor? Slow rod speed? Do you need to upgrade the rod to another diameter or make it longer?
I was

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that
I'm assuming your talking about no fins on the booster. I've seen it done as you described with other staged rockets that were VERY stable. It just depends on the rocket. Some it will work, others, not so good.
Randy www.vernarockets.com
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Pardon top posting but why use tape at all except absolutely necessary?
I modified my Zenith II with two vent holes in the sustainer/booster as described by G. Harry Stine in the Handbook. Have obviously not had any trouble with this model as it survived the E9-"homemade"-0 launch described above. I couldn't believe that staging wouldn't work without tape but by golly it does.
Kurt Savegnago
snipped-for-privacy@charter.net wrote:

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shockwaveriderz wrote:

I witnessed at least 4-5 flights of a CC Express with C11-0/C11-7 configuration today out at Lucerne, every flight was straight and true -- and obviously the rocket was recovered each time...
David Erbas-White
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Same thread is on rocketryforum.com
He used masking tape to tape the motors together.
He should use cellophane tape to tape the motors together. It holds breifly and melts uniformly at the joint. Masking tape takes much more time to burn through and takes much longer at the spot where it overlaps itself. Then you get the dangling booster effect (for a fraction of a second).
Go to Estes Educator website and download/print/read The Classic Collection.
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I always use cello.
Randy www.vernarockets.com
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Shockie,

I think that you were close to losing the booster prematurely. Accelleration and drag moved the booster backward, not the motor forward. Make sure that the bottom motor is secure in the booster. This will also keep the joint in the booster and prevent any side leakage, vectoring, whatever you want to call it.

I have not seen the sideways kick you have seen with an Apogee II, Comanche-3, or my Long Tom clone. They fly pretty much like a long burn rocket - once it starts at an angle, it will continue to increase angle unless otherwise motivated. It is suggested that you always angle into the recovery area, especially on staged flights, just in case the top stage does not light and you get a lawn dart. Motors taped end to end are less prone to this (Apogee II, CC Express) than gap stagers (Long Tom, 1st and 2nd stages of Commanche-3), but still will occasionally fail to light.
--
Tom Koszuta
Western New York Sailplane and Electric Flyers
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Shockie,
When I see this, my usual conclusion is that the booster tumbled in with the forward end hitting first thus causing the motor to shift forward.

One wrap of cellophane tape, no breaks. But do scrape the sustainer nozzles prior to taping to help the ignition.

They weather cock because they tend to come off the rod slowly, thus reducing the effective angle of attack with respect to the wind which in turn makes them more susceptible any cross wind.

I do it all the time. The key is making sure the 1st stage has enough thrust, or the rod is long enough, for the rocket to me moving at a good speed when it clears the rod. And that may mean putting a bigger lug on it. 6' long 1/8" rods ain't much help :) But 1/4" ones are great.
Doug
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And

Spooooyyy-ing, spooooyyy-ing, spooooyyy-ing, spooooyyy-ing ...dammit Bevis.......
Randy www.vernarockets.com
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