Dark Matter Propellant?

[neond7]

Has anyone had any experience with the Dark Matter RMS loads that I'm seeing coming out on some vendor's websites? Unlike the Metalstorm (white smoke) these have flaming sparks with black smoke. And unlike most of the Blackjack loads, they have a high ISP propellant. So far I've seen the following released:

38/360 H178DM
38/720 I327DM
54/1706 K456DM
75/5120 L900DM

I'm honestly a little disappointed that nothing has been released in a "J" load. The H187DM would be screaming in my Mad Cow Phoenix, but the I327DM is too under powered for my LOC Bruiser. And the K456DM would be a little too much for it since that rocket uses motor ejection and my luck it would end up in a tree miles away......

So, hopefully this is just the first batch of the DM loads certified with more in the works??

 

[CarVac]

You do realize that the K is only 1281 Ns, so it's basically a J+.

 

[neond7]

You do realize that the K is only 1281 Ns, so it's basically a J+.

Good point. I'll download the motor profile from Thrustcurve.com and import it into OpenRocket and run a sim on it and see what it does.

 

[neond7]

Ok, I looked up the K456DM-L 54mm Dark Metal - fits the 54/1706 case, which I unfortunately don't have.

Because its such a big/long motor, it looks like it makes my LOC Bruiser a bit unstable, it brings it down to .92 cal. It didn't seem to bother OpenRocket, which still showed all green for the simulation, with 22.9mph off the rod, 2533 ft apogee, and a max velocity of 297mph. I dialed in a 10 second delay for 8.1mph at deployment. And what a show it would produce!! Unfortunately, still a bit higher than I would prefer for motor ejection - our fields down here in Florida tend to be on the smaller side with lots of tall trees, swamps, etc.

Isn't .92 cal considered stable? Thought OpenRocket would flag that.

I also ran a sim on the I327 (38/720 case) and am more interested in that motor now. It keeps the stability at 1.24 cal and has an apogee of 737 ft. Not too bad for such a big, heavy rocket. That would be good for an impressive demonstration of the Dark Matter without putting the rocket out of sight. Maybe I'll get lucky and the onsite vendor will have one in stock at the field next Saturday.

 

[terryg]

The sparky motors are all about noise and special effects and are not as efficient as other formulas in the same case size. The "I" would give a spectacular low slow flight (1000 ft) and the "K" a chest rattling flight (3000 ft). Based on the stock rocksim file at EMMR (158 oz). I have not yet seen one fly, but from what I hear it is a case where people say "what the heck was that!" after the launch.

 

[Peter Olivola]

That's more than a bit slow off the rod. By about half what's considered safe. If you know how to plot a vector diagram try doing it with a 5 MPH wind to resolve apparent wind angle. You won't like what you see.

Ok, I looked up the K456DM-L 54mm Dark Metal - fits the 54/1706 case, which I unfortunately don't have.

Because its such a big/long motor, it looks like it makes my LOC Bruiser a bit unstable, it brings it down to .92 cal. It didn't seem to bother OpenRocket, which still showed all green for the simulation, with 22.9mph off the rod, 2533 ft apogee, and a max velocity of 297mph. I dialed in a 10 second delay for 8.1mph at deployment. And what a show it would produce!! Unfortunately, still a bit higher than I would prefer for motor ejection - our fields down here in Florida tend to be on the smaller side with lots of tall trees, swamps, etc.

Isn't .92 cal considered stable? Thought OpenRocket would flag that.

I also ran a sim on the I327 (38/720 case) and am more interested in that motor now. It keeps the stability at 1.24 cal and has an apogee of 737 ft. Not too bad for such a big, heavy rocket. That would be good for an impressive demonstration of the Dark Matter without putting the rocket out of sight. Maybe I'll get lucky and the onsite vendor will have one in stock at the field next Saturday.

 

[crossfire]

Seems like a small motor for the LOC Bruiser.
gp

 

[DAllen]

Ok, I looked up the K456DM-L 54mm Dark Metal - fits the 54/1706 case, which I unfortunately don't have.

Because its such a big/long motor, it looks like it makes my LOC Bruiser a bit unstable, it brings it down to .92 cal. It didn't seem to bother OpenRocket, which still showed all green for the simulation, with 22.9mph off the rod, 2533 ft apogee, and a max velocity of 297mph. I dialed in a 10 second delay for 8.1mph at deployment. And what a show it would produce!! Unfortunately, still a bit higher than I would prefer for motor ejection - our fields down here in Florida tend to be on the smaller side with lots of tall trees, swamps, etc.

Isn't .92 cal considered stable? Thought OpenRocket would flag that.

I also ran a sim on the I327 (38/720 case) and am more interested in that motor now. It keeps the stability at 1.24 cal and has an apogee of 737 ft. Not too bad for such a big, heavy rocket. That would be good for an impressive demonstration of the Dark Matter without putting the rocket out of sight. Maybe I'll get lucky and the onsite vendor will have one in stock at the field next Saturday.

If i were RSO I may not let a flight of a rocket that size go so low. Especially if there is any significant wind where weather cocking would be a huge concern. Wind could easily turn that 700' flight into a 500' flight. That is very little safety margin if there is a bonus delay. You could be looking at a chute coming out on the ground. :y: I've seen it before.

Personally, I would much rather see a rocket that large hit 1000'+ even with electronic deploy especially since sims seem to be optimistic on altitudes. I would say use the K motor and modify it for dual deploy or find a different rocket for the I.