Finally got around to compiling some of the video footage I got:
[video=youtube;zVprnNnDLe8]https://www.youtube.com/watch?v=zVprnNnDLe8&feature=youtu.be[/video]
While I would love to try again on an I540, the 5+ hour drive to potter to get the necessary waiver means it will probably be quite a while (next summer) before I get a chance to fly this thing again. I may wait until May next year to get my level 2, and then go fly this thing on some J motors.
So we know that this rocket can easily handle around mach 2 and 105+ G's. Do you guys think that it (specifically the fincan) could handle something like a CTI 6GXL J530 which would take it to mach 2.72, 60 G's and 19,500'? Or even better a Loki J1000, 110 G's, mach 2.8, and 22,000'?
Not sure if I explained earlier in the thread, but the fins are just under 3/32'' thick, CF with 6 layers of UNI CF oriented perpendicular to the BT and 3 layers of 3oz twill - so ridiculously stiff for this size fin. They are glued on with large Proline 4500 fillets.
I'm also dying to try this on the new 6GXl J150-MY, which would be (in comaprison) a nice gentle flight to mach 1.73, 24 G's and 19,000' with a 6.5 sec burn time...
Finally got around to compiling some of the video footage I got:
[video=youtube;zVprnNnDLe8]https://www.youtube.com/watch?v=zVprnNnDLe8&feature=youtu.be[/video]
While I would love to try again on an I540, the 5+ hour drive to potter to get the necessary waiver means it will probably be quite a while (next summer) before I get a chance to fly this thing again. I may wait until May next year to get my level 2, and then go fly this thing on some J motors.
So we know that this rocket can easily handle around mach 2 and 105+ G's. Do you guys think that it (specifically the fincan) could handle something like a CTI 6GXL J530 which would take it to mach 2.72, 60 G's and 19,500'? Or even better a Loki J1000, 110 G's, mach 2.8, and 22,000'?
Not sure if I explained earlier in the thread, but the fins are just under 3/32'' thick, CF with 6 layers of UNI CF oriented perpendicular to the BT and 3 layers of 3oz twill - so ridiculously stiff for this size fin. They are glued on with large Proline 4500 fillets.
I'm also dying to try this on the new 6GXl J150-MY, which would be (in comaprison) a nice gentle flight to mach 1.73, 24 G's and 19,000' with a 6.5 sec burn time...
With LDRS up in Potter getting close enough to start planning for, I've been thinking about what the next iteration of this rocket is going to be.
I've always wanted to fly a loki J1000, and with the release of the thrust curve of the new Loki 38/1200 K1127 a while ago, of course I had to have some fun in openrocket with it! What I discovered is that if I replaced my heavy filament wound NC with one of the new polycarbonate NC's that RW sells (https://rocketrywarehouse.com/product_info.php?products_id=748), I would be able to hit 21,000' and mach 3.00 with the K1127
Now, mach 3.00 is a big change from the I540 flight in terms of speed and altitude. If it burns normally, then it shouldn't pull significantly more G's than the I540 flight since it burned so much faster than the published thrust curve (it probably hit around 110-115 g's, and the K1127 is predicted at 124 g's). I'm not really worried about the altitude either; I have access to a very nice 3-D printer at my highschool, and I plan on printing an all in one electronics mount and unique dual deployment system so that it won't drift too far from 20k+.
What would worry me about the flight would be the speed. I am unsure if I need to add t-2-t CF layups to strengthen the fins. They are already extremely stiff at 3/32'' thick with a large percentage of the fibers being unidirectional CF perpendicular to the airframe. Also, I'd at a minimum coat the fin leading edges in black proline epoxy to protect them from delamination. Additionally, do you guys think the RW polycarbonate NC would be able to handle the stress/heat of the flight? I'm sure a FWFG NC can, but if I can save weight with the polycarbonate NC I will.
Lastly, though I don't want to start another huge stability argument :lol:, I was very surprised at the CP shift openrocket calculates for this flight. Using the component analysis which ignores the CG change during motor burn, the CP @ M=0.3 is ~3.5, M=1.0 ~4.1, M=2.0 ~1.5, and then M=3.00 its -0.6. Thats almost 5 calibers of CP shift from M1 to M3! :shock: Is this really realistic?
View attachment 254672
Thanks Nate! I have the numbers without the CG shift accounted for just to show how much the CP moves, which is what I was questioning. With the K1127 in flight it drops to ~0.5, which is too low a margin if it's truly accurate. (FYI the K1127 probably doesn't work because you need to download and import it from thrustcurve.com). I could easily add a couple ounces of weight to the NC to keep my stability well over 1 throughout the flight without affecting the altitude at all, but my speed would drop to the M2.85 or so, and I'd really love to brush up against M3
