"Eshak 2" And some Caliber of stability questions

[awseiger]

So, I have been constructing a very small 24mm minimum diameter rocket recently. I was going to fly it on an F240, but the idea of loosing a 24mm 3-G case made me rethink the idea. An SU F30 will get this one up way further than the eye can see it, so I think I'll stick with that.

Anyway, I was playing around in OpenRocket, and I noticed the "Cal" number at the top. I usually just built my rockets so that the spin-test made it stable, but this time, I wanted to do it the "Right" way. Anyway, my rockets usually sim out with the "Cal" at around 0.6 or 0.7. Apparently, I should be looking for numbers between 1 and 2. All my rockets flight straight as an arrow with this margin...

In order to achieve a cal of around 1 with an F30 in this model, I had to make my nosecone weigh nearly 54 grams... Which is a TON.

A picture, for reference:


It just feels to me that because this rocket is going to go crazy fast off the rod, that I can go for a Cal of around 0.5 or 0.6 and still remain stable. Then again, The last thing I want is a screwball 24mm motor.

[Rex R]

try making it an inch longer (in open rocket) and see where that gets you .

[awseiger]

It was longer at one point, but I got rid of the tube because it was extremely flimsy. I'll have to go buy myself some more BT-50 tube (I think that's what this is... I always mix up the Estes tubes).

I'd rather leave it the way it is, but if it really is that unsafe to have it below 1 Cal, than I'll do it.

[Rex R]

I was flying an estes super neon xl (stock)* on F24s, a friend of mine flies his big bertha on F39s...Estes tubes are stronger than one might think. provided the loading is evenly distrubuted along the long axis. my suggestion was simply to see how the itty bitty inch would affect the flight (in simulation). 0.5 cal is cutting the stability margin mighty thin for that type of rocket...if it were fatter then the base drag would assist stability.
*super neon is sleeping with the fishes.
rex

[awseiger]

Aha! I found Eshak 1 in the bottom of my parts bucket! I should be able to salvage a few inches of body tube off of it.... Here's to salvage operations! (And in a way, a Transplant)

*super neon is sleeping with the fishes.

Poor Super Neon Water landings are particularly hard on cardboard rockets...

Oh, And a little bit of cutting later... The extra 3.75 inches of BT I get from Eshak 1 decrease my nosecone mass by 20 grams...

[Rex R]

I don't imagine that the 24/40 case likes being submerged in goose droppings either .
rex

[accooper]

At the speed you are talking about in that rocket you want it stable. A land shark at that speed would be dangerous.

Andrew

[awseiger]

I agree, I was thinking that because it's going faster, the aerodynamic forces acting to stabilize the rocket would be stronger, and thus the rocket would be more stable...

Regardless, I added another 6 inches. Now I barely need any nose weight... and it looks better.