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-   -   URGENT! Help Needed for Girl Scout Rocket Project! (http://www.oldrocketforum.com/showthread.php?t=2175)

BatPlane 09-16-2007 03:46 PM

URGENT! Help Needed for Girl Scout Rocket Project!
 
I posted this under the "Current Kit" discussion. I apologize for the double-post and wouldn't do it otherwise but this is an emergency.

I am going to assemble 10 Estes Bullpup 12D #1972 kits with a bunch of Girl Scouts this week. My daughter and I assembled a test rocket last night and she got it together with little help from me.

HERE'S THE PROBLEM:

There are no engine clips! I mean, none in the instructions, none with the kits, none anywhere. We are going to do a test flight this afternoon but I can tell that without a clip, the engine is going to blow out of the back of the rocket (or fall out) as soon as the boost propellant is exausted.

I found the instructions at the link below. It looks like Estes re-released an old kit as the instructions are identical.

Bull Pup 12D Plans

Hopefully, I can buy some engine clips and retainer rings for the kits by this Thursday's meeting.

I was expecting engine mounting like what's described in these plans below: Estes Polaris Instructions:


Can anybody tell me what the heck happened with this kit? Any input is appreciated, thanks.


A Fish Named Wallyum 09-16-2007 03:49 PM

It doesn't come with a clip. Just put a wrap of masking tape on the engine before you install it. It's called "friction fitting". I've never had a problem with it. (Although getting the engine out can be an occasional trial.)

BatPlane 09-16-2007 04:30 PM

Thanks for the rapid response, Bill. Masking tape....hmmm, that sounds simple enough...makes sense, too. That sounds like it'd work OK. Something has to be done because the engine is literally falling out when you turn the rocket upright.

Even with the friction of the tape, isn't the engine going to blow out the back of the rocket instead of blowing the nose cone off?

I don't get it, why didn't this model come with a clip?

I intend to buy some extra clips and secure them with rubber bands (the hobby shop doesn't carry extra mylar bands) & super glue. Is it unnecessary?

Bazookadale 09-16-2007 04:32 PM

Yes, Friction fit it OR if the motor sticks out past the mount tube by 1/2 inch or more you could put a wrap of 3/4 inch masking tape around the outside of both the motor and tube. In either case make sure the motor won't come out without a strong pull. (Ii'm old enough to remember when estes put this in the engine instructions)

Edit: found this link showing a frition fit http://www.ninfinger.org/~sven/rock...a/69estp52.html

BatPlane 09-16-2007 04:51 PM

Awesome old instructions!!! Thanks! The engine on this kit is just about flush with the plastic tail cone so there's no way to tape the engine onto the rocket body if the directions are followed.

Maybe that's why there are no clips since there's not going to be much "give" when the engine is seated or unseated. The plastic tail cone prevents that (unless I cut a slit in it).

Well, I guess the tape is the way to go. Maybe I can tell the kids to not push the engine assembly quite so far into the body tube to allow me to get a grip on the taped up friction-fitted engine with some pliers to yank it out when it's recovered.

Oh yeah, this needs to be addressed as well....."I'd rather die with a burger in my colon then live on Tofu " That's TOO funny, man!

Rocket Doctor 09-16-2007 05:43 PM

Don't over do it with the tape.
If the engine doesn't stick out far enougk to grab it with a pair of pliars, you can take a dowel going from the front end up against the end of the motor.
The dowel must be able to fit through the engine block without resistance, gently tap, and I mean gently tap the dowel on a sidewalk whilr holding onto the rocket, don/t squeeze the rocket though.

This "friction fit" method was used before engine hooks came along.

Just curious, why did you select the Bullpup, the Baby Bertha would have been a better choice, no friction fitting there.

I requested that the Bullpup instruction be updated, I'm sure alot of the info is acient compared to current methods.

I sent several emails and discussed the issue, and the end results.....you fill in the black.

Good luck with you launch.

BatPlane 09-16-2007 05:53 PM

Rocket Doctor and everybody,

The Bull Pup was selected simply because it looks cool. I'm probably needlessly panicking because it's going to be tough getting about 10 girls to get the rockets together within a 60-90 minute time frame. I just don't want it to be a disaster for my daughter and her troop.

I test fit an engine and it's pretty snug. I stand corrected that the engine holder is flush with the plastic tail cone but the actual engine itself stick out about a half inch.

Taping the engine to the tail would work, masking tape friction fit will work. It's more snug than I thought so it'll probably work as is.

Thanks for putting my mind at ease, fellas. I should have done a test launch before posting. Thanks. - - Batplane

Solomoriah 09-16-2007 10:44 PM

Quote:
Originally Posted by Rocket Doctor
If the engine doesn't stick out far enougk to grab it with a pair of pliars, you can take a dowel going from the front end up against the end of the motor. The dowel must be able to fit through the engine block without resistance, gently tap, and I mean gently tap the dowel on a sidewalk whilr holding onto the rocket, don/t squeeze the rocket though.

I have a dowel, 3/8" I think, in my range box; I painted it flourescent orange so as not to lose it in the grass. I use it mostly to push wadding into narrow body tubes (as my fingers are a bit thicker than they used to be...) but it is long enough to drive out friction-fitted engines. I disagree with RD, though... I push them out with slowly increasing steady pressure, holding the body tube carefully to avoid damaging it, and have always had good luck getting them out.

I launched my Bullpup a few weeks back; I wrap tape in a rough spiral starting at the upper end. I put a single wrap on, and try it in the engine tube; if I can push it 3/4 in and pull it out again without difficulty, I put a second layer on; generally, that layer involves less tape. I'm not covering the entire engine, I'm just laying down some tape to make it stay in.

I guess it really takes practice to get it figured out...

Solomoriah 09-16-2007 10:48 PM

I do agree with RD regarding the Baby Bertha... you just can't find a better choice (at least in the Estes product line) when teaching kids. It's cheap, easy to assemble, and easy to fly (much easier to get the wadding in and the chute packed with a BT-60 than something claustrophobic like a Wizard).

A Fish Named Wallyum 09-16-2007 11:36 PM

Didn't this rocket require nose weight?


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