Anyone Flown The Blackhawk 54

[Cherrywaves89]

Im curious as to how you guys are simming 23,000', and 30,000' on an L935 and L265. I'm showing closer to 13,000' and 16,000'. I did see that some were using a thicker walled tube. Does that small amount of extra mass really give that much more momentum, or have I simmed something wrong?

 

[Neutronium95]

Im curious as to how you guys are simming 23,000', and 30,000' on an L935 and L265. I'm showing closer to 13,000' and 16,000'. I did see that some were using a thicker walled tube. Does that small amount of extra mass really give that much more momentum, or have I simmed something wrong?

It sounds like you have something severely wrong with your sim. I'm not certain about the exact performance of the Blackhawk 54, but it should do much more than 13,000 feet on an L motor. Can you share your sim file and post some screenshots of the design?

 

[Cherrywaves89]

 

[Cherrywaves89]

Here is the raw sim file with no edit.

 

[waltr]

Interesting. I got 19708 feet with the raw sim in Open Rocket on an L1000.

 

[3stoogesrocketry]

My Blackhawk goes close to 10k on a J800T. It's a great supersonic flight profile.

 

[Cherrywaves89]

My Blackhawk goes close to 10k on a J800T. It's a great supersonic flight profile.

Yeah, Im getting closer to 9,500, which isnt too far off. Might even be dead on with a tailcone retainer, but the differences with the L motors compared to @Neutron95 are concerning. In fact, there is a video of a Blackhawk out there where he flies an L990 to 20,500' and 1500mph, and my sim only takes it to 14,000' and 1300mph.

 

[thzero]

I slap together one in openrocket from the rocksim with a l265 and dragging in my dual deployment from my 54mm wildman, and tossing in second drogue chute I get 1990k at 1400fps, and with j800t I get 10k @1435 fps.

 

[3stoogesrocketry]

Yeah, Im getting closer to 9,500, which isnt too far off. Might even be dead on with a tailcone retainer, but the differences with the L motors compared to @Neutron95 are concerning. In fact, there is a video of a Blackhawk out there where he flies an L990 to 20,500' and 1500mph, and my sim only takes it to 14,000' and 1300mph.

What is your surface finish set to on the sim? Are your fins square ir rounded ? Are you having a deployment while still going up ( motor ejection charge ) ?

 

[GalantVR41062]

I use OR but would guess the simulation has a seperation event on the way up or tumbling due to the lack of stability margin for the flight profile.

 

[Cherrywaves89]

What is your surface finish set to on the sim? Are your fins square ir rounded ? Are you having a deployment while still going up ( motor ejection charge ) ?

I have checked all of those things you mentioned previously, and those things dont seem to be the issue either. I think I have nailed it down to being the inconsistent nature of OR and Rocksim past 10,000' and Mach 1. Its seems like RasAero is a better simulator for a flight
like this.

 

[mikec]

Certainly the file you posted deploys the chute at the first ejection charge.

If you intend to fly drogueless, you need to add a fake tiny drogue to get the deployment logic to work.

 

[Cherrywaves89]

Certainly the file you posted deploys the chute at the first ejection charge.

If you intend to fly drogueless, you need to add a fake tiny drogue to get the deployment logic to work.

That's just the raw file from Wildman. I have edited a version now with weight distribution and CP, CG, Cd all squared away.

 

[thzero]

That's just the raw file from Wildman. I have edited a version now with weight distribution and CP, CG, Cd all squared away.

Uh? So you changed the calculated CP? And then you are changing the Cd? Did you do a wind tunnel test?

 

[Cherrywaves89]

That is to say my slightly different fin placement, weight distribution, extra body tube length, and removal of rail guides have been all accounted for.

 

[plugger]

Uh? So you changed the calculated CP? And then you are changing the Cd? Did you do a wind tunnel test?

sorry, a wind tunnel test?!?

 

[Neutronium95]

I have checked all of those things you mentioned previously, and those things dont seem to be the issue either. I think I have nailed it down to being the inconsistent nature of OR and Rocksim past 10,000' and Mach 1. Its seems like RasAero is a better simulator for a flight
like this.

My personal rule of thumb is that Openrocket is reasonably accurate up until Mach 2 or so.