Can anyone with an Aerotech G-force manually test their center of gravity?

[readytorock556]

AT calls for CA because it makes the (on the fragile side) fins replaceable. Once you add epoxy fillets, good luck.

I just built a Arreaux with JB Weld because I got tired of a fine popping off on a not that hard landing. I will say I have built 4 Aerotech rockets with CA and all have flown many times with no issues. This one will be dual deploy and flown mostly high power.

 

[jmasterj]

I just built a Arreaux with JB Weld because I got tired of a fine popping off on a not that hard landing. I will say I have built 4 Aerotech rockets with CA and all have flown many times with no issues. This one will be dual deploy and flown mostly high power.

Doesn't it just pop back in, though?

I've been very happy with my 2x AT rockets built stock with CA, and I've seen many posts on TRF from the designer explaining why not to use epoxy.

 

[readytorock556]

Doesn't it just pop back in, though?

I've been very happy with my 2x AT rockets built stock with CA, and I've seen many posts on TRF from the designer explaining why not to use epoxy.

Yup, everytime. I figure I’m gonna put bigger motors and didn’t want a fin shredding on launch

 

[rcktnut]

Do you still have it by any chance? Could you do me the favor of checking your CG by manually balancing it? (No motor loaded) nice paint job btw

I'm hoping that soon you will forget about the need to know what some other persons G- Force rockets CG is. The only one you have to be concerned about is the one you have. Good work also on correcting the given CP of the G-Force on Aerotechs website. Good catch on the position of the fins.
I had a G-Force, long junked do to the rear end burning up on a motor with not enough thrust to lift it off the pad. I built it totally stock over 20 years ago and flew it a lot for years. Used CA on all my Aerotech kits (pics) never had a fin pop off. All my Aerotech kits are 20+years old.

One thing that with my experience is that it is not a matter of if but when will the tip of a fin will be cracked off. Every rocket that I have/ had with those fins have at least one tip crack off. I had one on the G-Force, one on my Astrobee D and two on my Mirage. That was with nominal flights in a farm field with dry hard ground. I learned not to fly them unless the ground was softened by some rain.

 

[overklock]

I'm hoping that soon you will forget about the need to know what some other persons G- Force rockets CG is. The only one you have to be concerned about is the one you have. Good work also on correcting the given CP of the G-Force on Aerotechs website. Good catch on the position of the fins.
I had a G-Force, long junked do to the rear end burning up on a motor with not enough thrust to lift it off the pad. I built it totally stock over 20 years ago and flew it a lot for years. Used CA on all my Aerotech kits (pics) never had a fin pop off. All my Aerotech kits are 20+years old.

One thing that with my experience is that it is not a matter of if but when will the tip of a fin will be cracked off. Every rocket that I have/ had with those fins have at least one tip crack off. I had one on the G-Force, one on my Astrobee D and two on my Mirage. That was with nominal flights in a farm field with dry hard ground. I learned not to fly them unless the ground was softened by some rain.

I'm afraid my incessant need to question every detail is a personality problem, rather than a rocket problem, but yes, you are correct, my rocket is the one that matters. But hey, extra data points matter. If it was just me out in a field alone I wouldn't care all too much, but for a level 1 cert with a lot of people around, I'd just rather be safe than sorry. I don't need my 1kg rocket doing loops over peoples' heads.

Cracked fins eh? I built an Arreuax and a Wart-hog a while ago, no problems yet, but it makes sense why Aero-tech charges so much for replacements on their website, probably the thing that breaks the most!

Beautiful rockets btw. Excellent paint jobs.

 

[rcktnut]

Thanks for the compliment. I never had a problem with any fins on the rockets except for the G-Force, Astrobee D and the Mirage. They all use the same fins and 3/8 to 1/2 inch of the fin tips broke off an landing.
Absolutely nothing wrong with being safe than sorry. I would say with the motor you are planning on using with your G-Force in the current state would fly just fine. Adding some nose weight isn't going to hurt either. Keep us informed on your L1 attempt, GOOD LUCK.

 

[overklock]

Thanks for the compliment. I never had a problem with any fins on the rockets except for the G-Force, Astrobee D and the Mirage. They all use the same fins and 3/8 to 1/2 inch of the fin tips broke off an landing.
Absolutely nothing wrong with being safe than sorry. I would say with the motor you are planning on using with your G-Force in the current state would fly just fine. Adding some nose weight isn't going to hurt either. Keep us informed on your L1 attempt, GOOD LUCK.

Glad you think it’ll fly well at least. That .23 stability margin in Rocksim scares me a bit. Gonna give it a go regardless. Thanks!

 

[tsmith1315]

I'm afraid my incessant need to question every detail is a personality problem, rather than a rocket problem

That's not a problem, just a trait.

 

[dmaaero]

Is the 44.88 CP, where the fins, the engine, an parachute location been moved the one i should use?
When compairing my CG to the CP do i use a engine or no?

 

[neil_w]

Is the 44.88 CP, where the fins, the engine, an parachute location been moved the one i should use?
When compairing my CG to the CP do i use an engine or no?

Always with engine, because that’s how it’s going to fly.

 

[overklock]

Is the 44.88 CP, where the fins, the engine, an parachute location been moved the one i should use?
When compairing my CG to the CP do i use a engine or no?

I'm assuming you picked up a G-force yourself?

The model that Apogee provides is totally inaccurate. You can use my model if you'd like.

The final flight configuration is what matters. So fully loaded.

 

[dmaaero]

I did get one overklock, but after a bad reaction to CA fumes, i used some epoxy on my bulkheads.
Mine CG"s at 39 1/4" loaded.
I plan to fly this one on some G"s (i have a G40-4W and a G77-4R for it). I"m in the process of building a Zephyr for my leval 1 attempt next spring.
All the Zephyr lacks is paint an the engine retainer (which is on the way).

 

[overklock]

I did get one overklock, but after a bad reaction to CA fumes, i used some epoxy on my bulkheads.
Mine CG"s at 39 1/4" loaded.
I plan to fly this one on some G"s (i have a G40-4W and a G77-4R for it). I"m in the process of building a Zephyr for my leval 1 attempt next spring.
All the Zephyr lacks is paint an the engine retainer (which is on the way).

Sounds like we're in the exact same boat, I just purchased a Zephyr lol. Going to try to be certifying this spring as well.

I posted a thread about my build process here: https://www.rocketryforum.com/threads/aerotech-g-force-build-thread-wip.176648/

And yeah, that CG is pretty far back. If Rockim's simulation holds true, that should still put it at a margin of >1 though. At this point I'm done worrying about the CG/CP on this rocket. Going to launch it and cross my fingers.

 

[rocketman328]

Is the 44.88 CP, where the fins, the engine, an parachute location been moved the one i should use?
When compairing my CG to the CP do i use a engine or no?

CG is determined with the rocket in flight ready condition, in other words with the Motor installed. If the Stability Margin is too low, add noseweight to move the CG forward. Also remember that as propellant is consumed the CG moves forward.

 

[rocketman328]

Sounds like we're in the exact same boat, I just purchased a Zephyr lol. Going to try to be certifying this spring as well.

I posted a thread about my build process here: https://www.rocketryforum.com/threads/aerotech-g-force-build-thread-wip.176648/

And yeah, that CG is pretty far back. If Rockim's simulation holds true, that should still put it at a margin of >1 though. At this point I'm done worrying about the CG/CP on this rocket. Going to launch it and cross my fingers.

If you add the payload bay from Appogee the CG will move forward or add nose weight and it will move forward. The Zephyr tends to be a little tail heavy especially if you use extra
epoxy to strengthen the fin attachment.