[roc-chat] Re: 18mm and 24mm E, F, and G motors

  • From: Erik Spjut <spjut@xxxxxxxxx>
  • To: roc-chat@xxxxxxxxxxxxx
  • Date: Sun, 5 Aug 2012 18:16:44 -0700

Hi Brian,

I overclock rockets all of the time. For 18 mm motor mounts I use either the 
single-use D21-7T (or 4T) or the Single-use D10-7W from Aerotech. Jack at the 
ROC launches usually has some D21s, but the D10s have to be ordered from 
ValueRockets or Apogee. I usually use either a Semroc miniAeroDart or a Quest 
Payloader 1, with a PerfectFlite Pnut. I usually get between 1500 ft and 1600 
ft out of them. Be aware that the Aerotechs have a far-too-large ejection 
charge and will rip apart any shock cord you use to connect the payload and 
body section, even on a fairly large rocket. Instead, I fly two 'chutes, one on 
the body, and one on the payload/nosecone. I also use an Aerotech Interlock 
Initiator Clip to connect to the copperheads. I've never had one fail with the 
interlock clip. The 18mm rockets are so small and fly so high, that you might 
want to think about just using single-use. I $40 motor casing kind of hurts 
when you lose it.

For 24mm, I have a Quest Superbird that I built with a 24mm mount, instead of 
the stock 18 mm, although anything with a 24mm mount should work OK. I also 
replaced the stock 'chutes with Top Flight thin-mil nylon 'chutes. I fly 
single-use E15-7W, E20-7W, and reload F39-9T. The rocket flies really well with 
apogee (from the Pnut) of about 1800 ft for the E's and 2200 ft for the F39. I 
tried an F32-8T. The rocket survived, but it didn't fly as straight as with the 
other motors. Checking the Pnut output, it hit the transonic region, which 
caused the less-than-perfect flight.

I'd be happy to share other results if you'd like.

Erik
On Aug 5, 2012, at 10:33 AM, Brian Morilak wrote:

> Hey rocchat!
> 
> For the next couple launches I am going to start eeking my away into the 
> high(er) power regime and noticed that although all of my rockets have 18mm 
> and 24mm mounts, there are various motors out there of these sizes that are 
> also F and G.  I am interested in trying out these motors, namely if the 
> on-site vendors have them, or if I can order them from some online locations. 
> I'd be using them to 'overclock' some proven capable Estes models, such as 
> the Bigdaddy and the Fatboy.   Any size recommendations to use in a model 
> like this that are known to be 18 or 24mm?
> 
> -Brian  

----
Prof. R. Erik Spjut (spyoot rhymes with cute)
Director, Engineering Clinic
Union Oil Company Design Fellowship Professor
Engineering Department, Harvey Mudd College, Claremont, CA 91711
Office 909-607-3890 Cell 909-367-9085 Fax 909-621-8967 Message 909-621-8020




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