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Well-Known Member
Jun 18, 2003
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While playing with Rocksim, I found a very interesting motor....... K185W...... I like the specs on this baby, 7.5 sec burn time...... I think it would make both my ISP Caliper and Expeditor fly real high!!!!!!!

But, I can't find anyplace that has them........ Has anyone heard if these are being (or going to be) producted?

Oh, Joe Burger.............
cool motor, I saw the J135 once (maybe it was the K I dont remember), the rocket kept going and going. After seeing the thrust curve on ATs website, it looks like this is a D grain load, though I may be wrong
are you sure? I just looked up a D grain and the thrust curve is exactly the same as on Aerotechs page. a Moonburner starts with a high thrust and then decreases. either way they are very similiar
It's a moonburner using a shallow c-slot. It has a similar profile of a D-Grain.. but a lot easier to make.

Even the instructions for the K185 say Moonburner (offset core) on them.
n3tjm is right - it is a C-slot....:)

Here is what a C-slot usually is. You take a small rectangular cross section out of the propellant and it is located on one of the sides. Hence if you look at the propellant that is there - it resembles a C.

Now a D slot you bisect the propellant at two points and take it out. It actually looks like a little D shape has been take out of the propellant. (The void is in the shape of a D)
Originally posted by Ryan S.
cool motor, I saw the J135 once (maybe it was the K I dont remember), the rocket kept going and going.

I looked at the specs for the J135...... I like it also........ And it seems that the J135 is available at more dealers than the K185........
The J90, J135, and K185 are all in the same family...
The J90 is for the short, stubby little case, the J135, the next size up,
and finally the K185 goes in the 1706 case, which is the same casing that the K550 uses.
I've flown a J90 before, and a couple of K185's...they are VERY cool motors, and they ARE C-Slots... there's basically a slot about 1/4" wide cut out of the side of the grain all the way down one side. With this style of motor, it's pretty much a necessity to use Phenolic for the liner, as paper will brun through very quickly, and the case will be toast.

On ROL, Joe Burger said they've been getting lots of requests for the J90, J135 and K185. He said they would like to start production on them as soon as they can, but won't be making a decision on that until April. The main holdup is that they haven't yet built the slotting machine needed to make these grains.
Originally posted by Chuck Rudy
You might be able to find something to your liking at Ellis Mountain......the L330 burns awhile but the cases ar a bit longer.

The Ellis L330 is a 3" diameter motor - I just can't seem to get it into my 54 mm mounts...
Originally posted by Ryan S.
Ryan... that is the funniest thing I read all day :). Good thing I was not drinking my tea when I read that ;)
Going to a quick change MMT system adaptability is the norm, not the exception. Note the three M class Loki casings for the Nike to the left side of the pic. The MMT system is the frame seen on the table. The motors are loaded into the MMT and not loaded into the rocket until it is on the rail. The larger plywood ring at the bottom acts as the thrust ring. This rocket can be set up for single, double, triple motors with a quick switch of the mounts. For a single motor setup you can have multiple sized centering rings stacked and ready to go at any time.
BTW Ellis Mountain just certed the following

SU 29mm G20-3 boost glider motor
SU 29mm H275 with a one second burn
38mm J228
54mm J110
54mm reloads J148 and a 2461ns K475
The K185 is (was) a c-slot grain...

I flew a few of them back before the 'end of Aerotech'.... they were lovely motors... had an oblong shaped C-slot just like the 24/29mm hobby reloads, but obviously on a bigger scale. The slot actually had a 'ramp' at the nozzle end where it tapered to get deeper (cut closer towards the core), I assume purely to let the igniter in/out easier rather than for any burn characteristic reasons.

I flew a Loc Syonic on one at LDRS back in 98... that was a lovely flight... and flew another as a sustainer in an altitude shot using head-end ignition. One thing I will say... slow WL is a b*tch to get lit! The one I flew in the Syonic took four attempts before it flew... even with Thermalite and dipped igniters it wouldn't light :-(

The igniter in the sustainer one was massive... it was actually a pair of Daveyfire 28F's, staggered and wrapped in ICI Slow fuse (similar to thermalite) and then the whole thing was dipped in a thickened pyrogen mixture... that lit it :)

All somewhat accademic as i assume they are no longer manufactured :-(


PS: I hope Antony C reads this and starts making some long burn loads for Pro-54 :)

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