Staging question

[KurtH]

Hello,
I am trying to get my first two stage rocket ready, the estes long Tom. My club's launch is tomorrow and I want to fly it. The directions say to use "cellophane tape" to tape the two engines together. Does that mean frosted scotch tape? OR can you recommend something better?

Thank you

 

[cobra1336]

Just plain cellophane tape works fine. Been that way for years. Anything thicker or stronger might give you problems.

 

[plano-doug]

Hello,
I am trying to get my first two stage rocket ready, the estes long Tom. My club's launch is tomorrow and I want to fly it. The directions say to use "cellophane tape" to tape the two engines together. Does that mean frosted scotch tape? OR can you recommend something better?

Thank you

The frosted tape is polyester, I think. I've used it with success. But the cellophane tape tends to hold the motors together a bit longer which helps to ensure the upper motor gets lit. I've been using it exclusively the past few years. I fly lots and lots of BP stagers, and have had a few fail to light over the years. It's ugly when that happens. So you try to give yourself every bit of help you can get

BTW, make sure you scrape the upper nozzle before you tape them together. I use as big a drill bit as will fit in the nozzle and give it a couple twists, then tap the nozzle on the table top. If I get a bit of black powder, I know it's ready. Then I tape them together.

As for the tape, look for the red packaging (instead of the green).

Doug

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[JStarStar]

Somebody posted on another thread that frosted ("Magic") tape is actually made out of mylar, which I would guess would have a higher tensile strength than cellophane, so at least in theory you could possibly run into some problems with stage separation, but in practice I have seen both used with good success.

As plano-doug says, it's probably good to rough up the ignition surface of the upper stage just a bit before flying. You want to make sure you have fresh BP exposed to the hot burn-through ejecta from the booster.

 

[shreadvector]

Somebody posted on another thread that frosted ("Magic") tape is actually made out of mylar, which I would guess would have a higher tensile strength than cellophane, so at least in theory you could possibly run into some problems with stage separation, but in practice I have seen both used with good success.

As plano-doug says, it's probably good to rough up the ignition surface of the upper stage just a bit before flying. You want to make sure you have fresh BP exposed to the hot burn-through ejecta from the booster.

Magic tape is Mylar which is a brand name of Polyester film.

The regular and cheaper cellophane tape has better adhesive to hold the stages (motors) together better and the melting point of the tape seems to be better for muilti-stage use (it takes a bit longer to melt than the very thin polyester/Magic tape).

Generic versions of cellophane tape are often sold in discount or dollar stores.

 

[Marc_G]

I get nervous at the idea of taking any sort of tool to the black powder... I just tape with whatever transparent/frosted is handy (one wrap only) and have had good success.

 

[plano-doug]

I get nervous at the idea of taking any sort of tool to the black powder...

After this happens once or twice, you'll get over it

These are all staging failures. Out of well over a hundred, I've had very few failures, but every once in a while it happens. I have attributed at least 3 to failure to clean the nozzle. Sometimes, no matter what you do, stuff happens. But not cleaning the nozzle is asking for trouble.

Doug

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[shreadvector]

Never drill into the black powder. Doing so is stupid and indicates that you do not know why the upper stage is not igniting and so you "flail" and try something desperate and potentially dangerous.

Use your brain: You simply need an upper stage motor with a clear black powder propellant "target' that the flaming bits from the booster motor can hit and ignite.

* Look into the upper stage nozzle with a bright light (like the cheap LED flashlights you can get at Harbor Freight or anywhere else, or a small MagLight). If you see the black powder, then it is good to go. If you see nozzle clay, then select another motor or clean the clay from the surface with a wooden toothpick or a straightened paper clip. Do not drill.

* You can find r select an upper stage motor with a larger nozzle throat and a correspondingly larger black powder "target" surface, such as an Estes A8-5 or B4-4 (yes, the B4-6 would be nice to have back). D12 motors have a much larger nozzle throat than a C11 or E9. German Quest motors have large nozzle throats. I'm not sure about the Chinese Quest motors - anyone out there compare or measure them?.

* Another mode of upper stage ignition failure is inadequate taping or a gap-staged model with no vent holes. The stages need to stay connected long enough for the upper stage motor to be hit by and ignited by the faming bits spewing out of the top of the booster motor. If the stages op apart too fast, the upper stage ignition will not occur. Securely taped together motors (with one or two wraps of good cellophane tape) is excellent. Gap-staged models need vent holes between the motors to allow the cool air out as the booster blow through pressurizes the interstage area. The cool ari can escape and the stages stay together until the upper stage ignites and THEN the pressure is so great that the stages pop apart.

* And make sue the booster motor cannot be blown out of it's booster stage or the stage may stay attached and get roasted byt eh upper stage motor.

* Also, make sure the nose cone is not too loose or it will fall off at staging (the "train wreck" - the rocket decelerates and the nose can fall off just before upper stage ignition).

 

[MarkII]

I get nervous at the idea of taking any sort of tool to the black powder... I just tape with whatever transparent/frosted is handy (one wrap only) and have had good success.

I have never scraped the propellant pocket just inside the nozzle, yet I have never had a staging failure.

 

[KurtH]

Thank you for the help. I used Cello tape today, and had two successful staging launches. I Scraped the sustainer on the first flight, but I forgot to scrape the second one, but it staged well any way. The only problem was the motor mount ejected it self on my second two stage flight, so that rocket was done for the day.

 

[dragon_rider10]

Just chiming in here, I do fly staged flights every now and then, but have never scraped a motor. Several of those flights were 3 stagers (Comanche III) I have never had a failure caused by faulty ignition of the sustainer. Most common failure: lost rockets.

 

[shreadvector]

As i tried to say somewhere up above, you should simply inspect the upper stage motor with a flashlight (like an LED light from Harbor Freight) to make sure you can see dark propellant. If you see clay - the stuff the rest of the nozzle is made from - then you need to scrape the clay dust or thin layer of clay away. But that scraping should be done with a non-sparking tool. And "scraping" is not "drilling".

Typical tools include a toothpick or a straightened paper clip.

Once you confirm that you see propellant, you are good to go (as long as you use either cellophane tape for motors that touch or vent holes for motors that are "gap staged").