Mean Machine Coupler Question

[El Cheapo]

Are the stock couplers supplied in the Mean Machine kit sufficient in length to keep the BT's from buckling while using D,E & F composite reloads or do I need to order some full-length couplers and double or triple the length from 3" to 6 or 9" couplers.

Thanks in Advance,
El Cheapo

 

[shreadvector]

The couplers do not stop buckling. They couple the tubes.

Tubes are a form of "column' and they will buckle at any convenient weak spot (so don't dent or damage them) or they will buckle in the exact middle. The newest version of the MM has a massive coupler in the middle and this will help.

Oh yes, the tubes need to be coupled very straight. if there is eccentricity (if they are crooked) it will induce airloads that make it want to buckle.

"Euler"


https://en.wikipedia.org/wiki/Buckling

 

[kandsrockets]

I used 4" long couplers on mine and also made mine break in the middle. I put a 29mm motor mount in and have flown it on G33's with no problems.

 

[El Cheapo]

SV, I understand what you're saying and perhaps I worded my question a bit off kilter. My thinking in using longer couplers is that it would diminish the amount of single-wall surface area, thus decreasing the probability of buckling, much like Scott did on his.

I, too, am going to make this a center break.

I was just curious if anyone has flown one on composite 24mm in stock form or if they've beefed it up a bit.

 

[gpoehlein]

Check out the reviews at EMRR - several flights of the Mean Machine are listed as flying on composite F motors. Some were more successful than others.

https://www.rocketreviews.com/reviews/all/est_meanmachine.shtml

 

[RocketMonkey]

as long as the tubes are glued straight you should have no problem. Check out the "speed of cardboard" thread in the HPR section, I have put my stock MM up on F39's a bunch of times with no ill effects.

 

[Pantherjon]

If you are worried about it, buy some extra couplers and put them in the whole length of the rocket thereby 'double walling' it..Would be prety stout after that.