Old Style Stovi clustering

Edit!I wasn't clear in my original post.
I am wanting to fill the some of the boosters with motors and cluster on an old style Stovi kit. Each of the tubes is 24mm. I would be putting D12-5 or E9-6 in the boosters if I can't find D12-0 or E9-0 motors when I go to launch. The end of the boosters has a solid bulkhead. I want to drill a discrete hole into the tubes to vent gasses or burn through pressure. I didn't think to check the handbook, and I did some searches but did not find good or safe information. So, I wanted to know what size hole to drill in the tube to vent each tube. Yes, I know that the original Stovi was not intended to be clustered.

Original Post:
I am assembling an old Stovi kit, which I plan on clustering. I know I could buy D12-0, E9-0, E12-0, etc. for the boosters and then epoxy the end to plug them. However, I can't always locate a D12-0 or E9-0 and none of the local shops sell anything E12. So, I was thinking about drilling a hole into each booster to vent the ejection gas. How large of a hole would be big enough in a 24mm tube without overly weakening the tube? There are 7 of these tubes epoxied together, so they will have a lot of support from their neighbors.

Two 1/4-inch diameter holes on opposite sides of the tube just below where the nozzle of the upper stage motor would be. From Handbook of Model Rocketry, page 172. I have used 1/8 holes with good success.

etoyoc said:

I am assembling an old Stovi kit, which I plan on clustering. I know I could buy D12-0, E9-0, E12-0, etc. for the boosters and then epoxy the end to plug them. However, I can't always locate a D12-0 or E9-0 and none of the local shops sell anything E12. So, I was thinking about drilling a hole into each booster to vent the ejection gas. How large of a hole would be big enough in a 24mm tube without overly weakening the tube? There are 7 of these tubes epoxied together, so they will have a lot of support from their neighbors.

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First I must correct you...D12-0, E9-0 and E12-0 Motor DO NOT have an ejection charge PERIOD. All you have in Booster -0 motors is Propellant. yes they do produce an Very small amount of burn through pressure but it is not intended to be used as an ejection vehicle. I have seen the After burn FLAME on -0 motors as small as A3-0t's last as long as a full second after burn out and reach 2 to 4 inches in length. That's the more important thing to consider.

OBTW Just so you understand what your doing! Epoxy Plugging ANY motor is a violation of the model rocket safety code, Cancels your NAR insurance and could (worst case) land you in jail for altering a manufactured motor in a manor not recommended by the motor manufacturer..... In other words DO NOT DO IT!
Most RSO's in the USA will not allow such motors to be flown an any public attended launch and are generally confiscated from the person presenting or having such motors.

If you want to vent the burn through gas pressure from your booster pods an alternative to drilling holes in the body tubes is to cut 1/8" breaks in the centering rings. I do this on just about all my Clustered models that are one body tube size bigger then the motor or larger. If they are minimum diameter BT-50's then a single 1/8" hole is really all that's necessary 1/4" is almost to large and noticable. I'd CA reinforce the perimeter of the hole(s) just to keep the edges nice for a longer time remember that afterburn flame WILL vent through this hole charring the hole edges and discoloring the paint. You might want to place such vent holes in a Black or Dark color patch to mask this effect.
If you just plan on venting standard BP ejection charges then two- 1/4" holes are the recommended size.

Have you checked the Local Wal-Mart? I recently Picked up 5 pack of D12-0 motors from one in my neck of the woods.
Belleville wholesale Hobbies stocks and ships -0's fairly inexpensively try them at www.bellevillehobby.com

Hope this helps a little.

Micromeister said:

First I must correct you...D12-0, E9-0 and E12-0 Motor DO NOT have an ejection charge PERIOD.

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I stated that I could use D12-0, etc.. . However, I am not going to be using those and and would be putting a regular D12-5 in the booster which does have an ejection charge. I should have made that clearer.

Micromeister said:

OBTW Just so you understand what your doing! Epoxy Plugging ANY motor is a violation of the model rocket safety code, Cancels your NAR insurance and could (worst case) land you in jail for altering a manufactured motor in a manor not recommended by the motor manufacturer..... In other words DO NOT DO IT!

Click to expand...

This is actually the main reason that I do not want to mess with epoxy in the motor. I must have been distracted while writing my original post, and did not write clearly enough. Again, I know I could do it this way. However, I have no intention of actually doing things this way. I would rather vent the gas out of the rocket.

Micromeister said:

If you want to vent the burn through gas pressure from your booster pods an alternative to drilling holes in the body tubes is to cut 1/8" breaks in the centering rings. I do this on just about all my Clustered models that are one body tube size bigger then the motor or larger. If they are minimum diameter BT-50's then a single 1/8" hole is really all that's necessary 1/4" is almost to large and noticable. I'd CA reinforce the perimeter of the hole(s) just to keep the edges nice for a longer time remember that afterburn flame WILL vent through this hole charring the hole edges and discoloring the paint. You might want to place such vent holes in a Black or Dark color patch to mask this effect.
If you just plan on venting standard BP ejection charges then two- 1/4" holes are the recommended size.

Click to expand...

Yes, the Stovi is min diameter 24mm tubes. I like the idea of the gaps in the centering rings. However, it will not work on this model. I will keep the idea in my back pocket for another rocket!

d10srule said:

Two 1/4-inch diameter holes on opposite sides of the tube just below where the nozzle of the upper stage motor would be. From Handbook of Model Rocketry, page 172. I have used 1/8 holes with good success.

Click to expand...

The 1/4" size is all I was looking for. Why didn't I check the book first? I don't know. Again, I must have been distracted while I was typing. I thought I might be able to put the 1/4" someplace it would be out of view, but I would rather go smaller. Thanks!

I used a single 1/4" launch lug, canted at about 45 degrees to vent mine. I didn't think I could hide the hole so I made it look like it's suppposed to be there.

Rocket86 said:

I used a single 1/4" launch lug, canted at about 45 degrees to vent mine. I didn't think I could hide the hole so I made it look like it's suppposed to be there.

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Nice! I am going to look and see if I have enough 1/4" LL. Otherwise, there are plenty of tubes from igniters that could do this!

I have always made plugged motor out my D12-0s for this purpose.
You just cut a circle of masking tape just a little bigger than the motor's open end and then pour in a 1/4 inch of 5 or 15 min epoxy.

Micromeister said:

Epoxy Plugging ANY motor is a violation of the model rocket safety code, Cancels your NAR insurance and could (worst case) land you in jail for altering a manufactured motor in a manor not recommended by the motor manufacturer.....

Most RSO's in the USA will not allow such motors to be flown an any public attended launch and are generally confiscated from the person presenting or having such motors.

Click to expand...

Well that's a little dark. While any RSO would do well to refuse an experimental motor at a commercial launch, and while NAR insurance only covers commercial motors, this is the first I hear of anybody going to jail or losing property over modifying a BP motor.

Ari.

I removed my post for obvious reasons, but NO ONE, may steal one's property. You will never convince me otherwise. We are not the motor police, or law enforcement of any kind for that matter.

iter said:

Micromeister said:

Epoxy Plugging ANY motor is a violation of the model rocket safety code, Cancels your NAR insurance and could (worst case) land you in jail for altering a manufactured motor.....

Most RSO's in the USA will not allow such motors to be flown an any public attended launch and are generally confiscated from the person presenting or having such motors.

Click to expand...

Well that's a little dark. While any RSO would do well to refuse an experimental motor at a commercial launch, and while NAR insurance only covers commercial motors, this is the first I hear of anybody going to jail or losing property over modifying a BP motor.

Ari.

Click to expand...

And now you understand why Tripoli got started.

Handeman said:

And now you understand why Tripoli got started.

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Also, the Due Process clause in the 5th amendment, seeing as Micromeister is talking about RSOs in USA.

No person shall be ... deprived of ... liberty, or property, without due process of law

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jazzviper1 said:

I have always made plugged motor out my D12-0s for this purpose.
You just cut a circle of masking tape just a little bigger than the motor's open end and then pour in a 1/4 inch of 5 or 15 min epoxy.

Click to expand...

I learned how to do this on this forum.

I think epoxy plugging a -0 motor might not constitute "modifying" the motor, any more than wrapping tape around the nozzle end to create an external thrust ring would. In no way does plugging a motor modify any of the performance characteristics of the motor. The NAR addressed this issue several years ago (see NAR Engine Testing Notice R63 below), addressing the external issue but they did not specifically address plugging a -0 motor. The same logic would likely apply though... you might want to actually ask the NAR about it. I've seen people stuff wadding in the empty space and tape it in, if that's permissible then so should be plugging.


Engine Testing Notices

R63 NAR S&T Clarification 23 Jul 2000
In response to member and manufacturer requests, the NAR Standards and Testing committee has examined the question of gluing something (such as a thrust ring) to the external surface of a rocket motor casing. We find that this does not modify the motor case and so long as it does not modify motor performance, this does not violate the NAR safety codes.
Note that NAR Contest Rules (the "Pink Book") may require further limitations for NAR Contest flights.
Jim Cook,
Secretary for NAR Standards & Testing
Jack Kane,
Chairman

etoyoc said:

Yes, I know that the original Stovi was not intended to be clustered. [/I]

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Actually, yes the Stovi along with MANY of LOC's older models was intended to be clustered. Could be built as 7x24mm cluster, or central 29 with dummy 24mm "tanks". I don't know how it's kitted now (if still available), but that was the original intent!
-Ken

It is easy enough to test fire a black powder booster motor, plugged by any suitable means. I have done so using epoxy as the plug. The motor was plugged, secured to a rigid mast with the nozzle pointing up and ignited electrically. It burned normally and then simply extinguished itself. I think I shall repeat this experiment by driving a 1/2" x 36" long wooden dowel sharpened on one end into the ground and gluing the other end into the cavity on a C6-0 booster and when the glue has set, test fire it. And, I'll post a video on YouTube and listen for the howls of the protesters.

I'm back with the results of my crude testing of plugging Estes black powder booster motors. The first video shows what would probably happen if a booster motor were fired while in a motor mount without being solidly plugged. The second video shows would happen if the motor were solidly plugged.

[video=youtube;E98rlFZmuOE]https://www.youtube.com/watch?v=E98rlFZmuOE[/video]
[video=youtube;wBO99FPxgGY]https://www.youtube.com/watch?v=wBO99FPxgGY[/video]

I would have no problem building a rocket with a central motor surrounded by two or more solidly plugged motors.