DAllen
Well-Known Member
Has anyone ever intentionally added weight to the rear of a rocket to alter the stability? Or for any other reason?
Yes - by adding a bigger motor.
Has anyone ever intentionally added weight to the rear of a rocket to alter the stability? Or for any other reason?
What motor and launch weight did you fly ?
Kenny
Maybe I'm missing something here...
Rocket was fine with the original nosecone.
Nosecone got busted, so you replaced it with a heavier one.
Now the rocket is over-stable, weathercocks, and doesn't go as high as expected.
How to fix?
Buy the correct replacement nosecone from RW.
https://rocketrywarehouse.com/product_info.php?products_id=196
Why do people want to avoid weather cocking? Wouldn't the wind tend to bring the rocket back to the launch site during recovery as opposed to having it drift farther down range if the rocket had gone straight up? (Sorry if this is a dumb question, but I'm pretty new and just trying to understand things.)
Why do people want to avoid weather cocking? Wouldn't the wind tend to bring the rocket back to the launch site during recovery as opposed to having it drift farther down range if the rocket had gone straight up? (Sorry if this is a dumb question, but I'm pretty new and just trying to understand things.)
Why do people want to avoid weather cocking? Wouldn't the wind tend to bring the rocket back to the launch site during recovery as opposed to having it drift farther down range if the rocket had gone straight up? (Sorry if this is a dumb question, but I'm pretty new and just trying to understand things.)
Seriously? 4000 ft. is hardly HPR territory.
Wind at altitude must be considered an have much impact on weather cocking regardless of stability.
The problem I have with weathercocking is that it's neither controllable not predictable. You can figure if a rocket has a tendancy to weathercock, but until you hit the button you won't know by how much it's going to happen.
Seriously? 4000 ft. is hardly HPR territory. .
J360-SK, 16.2 lbs. loaded.
There's your problem. Unless the J360 has some bizzare curve. No need to look farther.
Since someone dredged up this thread, I'm happy to report that I have been able to fly this rocket on the J1520 VMAX to about 3000 with absolutely no weathercocking. I intend to try the J760 at the next launch. My problem was definitely not having enough speed off the pad.
Why did you dredge up a 2.5-year-old thread? I solved the problem and don't even have this rocket any more. :confused2:
Funny me I thought forums where for the benefit of the entire community it serves, NOT just for the person who made the original post.
I stand corrected. However, you were solving a problem that was already solved earlier in the thread, so maybe there was no benefit to the entire community. :wink:
John, I'm prepping a rocket for my L2 right now. Similar concern taking note of margin of 3, but weights are about the same as your rocket. I dismissed using anything in the 300 range early, just not enough trust. Even 400s might be marginal on a windy day. Very good chance I will use a J1055 vmax as the J760 just takes it to high for a shakedown flight. Want to see what's going on.
This sounds like you're using the average thrust that is part of the motor designation
to make a determination of thrust to weight off the pad...
This is a very unsafe practice...
Motor thrust curves are not flat..
Always check the thrust curve,, it's the first quarter second or half second that counts...
This is why long burns usually have a spike in the thrust curve as soon as they ignite...
Teddy
Nope, not doing that at all Teddy...
Launch guide length: 71.9992 In.
Velocity at launch guide departure: 80.8015 ft/s
The launch guide was cleared at : 0.161 Seconds
User specified minimum velocity for stable flight: 45.0000 ft/s
Minimum velocity for stable flight reached at: 23.8709 In.
...but actually the vmax is pretty flat. :wink:
https://www.thrustcurve.org/simfilesearch.jsp?id=1303
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