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

  • From: "Ron McGough" <rrmagoo7@xxxxxxxxxxx>
  • To: <roc-chat@xxxxxxxxxxxxx>
  • Date: Mon, 6 Aug 2012 11:33:47 -0700

Brian,
Just to let you know that modeling clay isn't the best way to weight your nose 
cone. In the heat of the day it can become soft and runny and then loose it's 
cohesion to the inside of the nose cone. It then slams down too the base of the 
cone changing your CG and compromising the ability for a stable flight. Don't 
ask how I know this. I recommend epoxy and lead shot or even BB's if you can't 
get a hold of lead shot.

Ron McGough
  ----- Original Message ----- 
  From: Brian Morilak 
  To: roc-chat@xxxxxxxxxxxxx 
  Sent: Monday, August 06, 2012 11:17 AM
  Subject: [roc-chat] Re: 18mm and 24mm E, F, and G motors


  Thanks for all the good sounding advice.  Yeah, I have some modeling clay 
left over from a couple other kits that I will pack into the tip of the nose of 
the Fatboy.  I'm willing to OC the Bigdaddy without increasing nose weight 
because it seems there's a lot of CG margin in stock config.  And the fins are 
already pretty dang thick.   I got a pretty robust upgrade kit for the 
Fatboy,incl plywood fins and cloth chute but there doesn't seem to be room for 
it in the body now, might use it in the bigdaddy instead, or I'll find a 
smaller cloth chute.

  Oh and I also picked up a Madcow Squat on my 4 hour trip to Yuma...54mm 
mount.  I am thinking ahead. :D  Now, to get these dang college loans payed off 
BEFORE I go for lv1... 


   
  On Sun, Aug 5, 2012 at 6:16 PM, Erik Spjut <spjut@xxxxxxxxx> wrote:

    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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