Never expected to see a Reddy Kilowatt reference on TRF!
I have the t-shirt!The_Quacken --
I like your Reddy Kilowatt stickers !
But don't you need one of these from the good-old days too ?
View attachment 592164
Maybe the switchblade should be a silhouette of your rocket ?
Naah ! The lawyers would never let that fly !
-- kjh( who has a sick sense of humor )
There are several styles here:
google images: Reddy Kilowatt
This is the tinder rocketry one. Same guy who makes tender descenders. They work with black powder and smokelessWhat do youuse for a Cable Cutter ?
Yes it’s the same packing even. it shows the soft shackle I’m using for recovery attachmentQ[2]: Is the package in the photo on the right for the same 54mm Rocket ?
Is this something with NAR? I sure see a lot of aluminum tips these days.Also, I'm not sure if this rocket would even be allowed to compete at Hamster Dance. There was some controversy last year about an Aluminum nosecone tip.
Yeah it’s cutting too many things too close so I’m gonna call it out for HD. Unfortunate but there’s always next year.Significantly reduced stability can be a problem when flying shorter motors in compact minimum diameter designs intended for longer motors. With a full length motor like a L1000, a pretty significant fraction of the motor mass is ahead of the CG, and going to a smaller motor can bring it back a lot. When you add in the fact that the fins aren't swept back like on many other minimum diameter designs, you'll end up with a CP that's further forward in comparison to something like a Wildman Mach 2.
Don't play silly games with stability. If it needs noseweight, add noseweight, especially for the K1103. The CP shift at Mach 2+ is no joke. You might be able to get away without extra ballast for the K76, but I wouldn't risk it. Also, I'm not sure if this rocket would even be allowed to compete at Hamster Dance. There was some controversy last year about an Aluminum nosecone tip.
<<<snip>>>
Don't play silly games with stability. If it needs noseweight, add noseweight, especially for the K1103. The CP shift at Mach 2+ is no joke. You might be able to get away without extra ballast for the K76, but I wouldn't risk it. Also, I'm not sure if this rocket would even be allowed to compete at Hamster Dance. There was some controversy last year about an Aluminum nosecone tip.
Significantly reduced stability can be a problem when flying shorter motors in compact minimum diameter designs intended for longer motors. With a full length motor like a L1000, a pretty significant fraction of the motor mass is ahead of the CG, and going to a smaller motor can bring it back a lot. <<<snip>>>
I’d appreciate that a lot because then I could at least put a weight element in the right ish place.p.s. if you don't have an AT RMS 54/1706, I could weigh mine with the end closures and the forward seal disk ...
Yeah I did that’s why I was so suprised by the stability. I wouldn’t have built it if OR had told me it was so marginalAnd I assume you measured the CG on the physical, loaded stack to come up with the stability margin using the CP calculated by Open Rocket ?
@The_Quacken --I’d appreciate that a lot because then I could at least put a weight element in the right ish place.
But yeah OpenRocket just stuck a short 1706 case in which is why I believe the cg will be much farther forward making it safe. That’s partially why I think I may just put the “here’s 8% stability” on the rocket since the sims are sus. I also need to ensure the fins are the right shape. The weird rounded shape means I need to either free form or approximate. With sharp corners or a guess at free form. I think they are pretty accurate but still.
I don’t think it’ll sky write but it’s looking like itll be a little uhhh wiggle wiggle right off the pad
Make Component SSN Date Len(in) Mass(g)
-------- ----------- --- ----- ------- --------
ISP RMS-54/1706 205 04/93 15.0 268
AeroTech RMS-54/1706 839 09/95 15.0 272
AeroTech Std Fwd Closure --- ----- 0.875 104
AeroTech Plugged Fwd Closure --- ----- 0.875 102
DrRocket Extended Fwd Closure --- ----- 1.375 106
DrRocket Aft Closure --- ----- 0.375 30
That's exactly what I do if I need the sim to have that level of accuracy in predicting stability. Can even add a separate mass element for the floating closure so that the cg of the phantom case section is right.Maybe one should sim with the K1103 in the 'native' RMS 54/1706 casing and then add a virtual static cylindrical mass just forward of where the forward closure of the 54/1706 would be ?
I think it will because I had a placeholder (aluminum tube component that I just relied on OR to do the right ish mass for since it was a case thickness) and it seemed stable and then when I removed that to test the k76 it did the crazy shift but I’m about to go home so I can send real dataThat's exactly what I do if I need the sim to have that level of accuracy in predicting stability. Can even add a separate mass element for the floating closure so that the cg of the phantom case section is right.
Will be interesting to know if it makes much difference in this case.
Thanks for the reference to '54 parts from rcs', @The_QuackenSo I may end up scrubbing the k76 launch but for a much lamer reason. It comes down to funding it rn. 54 parts from rcs are expensive <<snip>>
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