1/8th Inch Lug on a D Engine?

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Well-Known Member
Dec 29, 2003
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Is it OK to use a 1/8th inch launch lug on a rocket that will use a D engine? I remember reading that past a C you should go to 3/16ths but the Apogee website sells 1/8th for up to D and 1/4 for above. I would use 3/16th just to be on the safe side but I'm all out...

I'm building a Baby Bertha I've modified for a 24mm engine. Sims to 1100 ft so I reinforced the fins with bond paper and CA so I can use a streamer for recovery.


I have flown dozens, and probably a few thousand other guys have done it too.
It is the standard size LL that Estes puts in its D and E kits.
Go for it!
I set my D powered fatboy up this way and have had no problems at all. I think it's only necessary if you are flying a very large rocket such as maxi alpha 3, big daddy, super big bertha etc..........
it would work, but your flight not be perfectly straight because an 1/8th inch rod is not as stiff
Strictly speaking, I don't think it is the size of the motor that
determines which rod to use, but rather the weight of the
rocket, how much wind it catches (big fins) and how windy it
is. Of course, typically, your larger motors are used with
heavier rockets, but that is not always the case. The thing
to ask yourself is... Under the current weather conditions and
the angle that I've tilted the rod, as the rocket slides up the
rod, will it bend it a lot. A minimum-diameter lightweight
rocket will fly just fine on a D or E with 1/8" if it is not too windy.
Even a rocket flying a C motor but has really big fins or wings
that catches the wind might need a thicker rod.

In teh Handbook it says he has launched an F off a 1/8 36" rod.

You should be fine, but i prefer to use 3/16 if possible.
A few examples of "D" powered Estes rockets that go with the 1/8" lug: Goblin, Cherokee D, Skybolt, Renegade, Defender, Ranger (circa 1990 reissue).... I could go on. ;)

As is stated above: the key is going to be the length, weight, and fin size of the rocket - not necessarily the total impulse of your engine(s).
Thanks everybody--this all sounds reasonable.

And it's not actually a Baby Bertha anymore. I was looking at my nosecones and thought that an ogive might look good up in place of the Bertha cone. Now it looks like a Baby V2! Less nose weight needed too.

I'm thinking of a White Sands paintjob...