John Taylor
Well-Known Member
I cant find a H185.
EZI-65 Build (Junior L1)
- Thread starter Lukun7
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John Taylor
Well-Known Member
Depending on who you certify with you probably will have to have the accurate weight, the center of pressure, and the center of gravity available.
Lukun7
Young Rocketeer
Okay thanks i'll find them
John Taylor
Well-Known Member
The center of pressure on an EZI-65 is 11.3" from the aft end. Mark the CP on your rocket.
The center of gravity (balancing point with everything installed including motor and all) needs to be at least 1 caliper (body width or 4" in your case) forward of the center of pressure to be stable.
Mark the center of gravity on your loaded rocket. These mark's make it easy for the RSO to check your rockets stability.
Anybody reading this and disagreeing with this information or can add advice please speak up.
I believe you will do well.
The center of gravity (balancing point with everything installed including motor and all) needs to be at least 1 caliper (body width or 4" in your case) forward of the center of pressure to be stable.
Mark the center of gravity on your loaded rocket. These mark's make it easy for the RSO to check your rockets stability.
Anybody reading this and disagreeing with this information or can add advice please speak up.
I believe you will do well.
Lukun7
Young Rocketeer
It appears to be super overstable, with a margin of almost 3 calibers. The CG is around 22 inches from the aft end. I'll measure again once the paint is dry tomorrow night and the parachute is attached to the nose. And I did measure with the parachute in, just not attached to the rocket.
John Taylor
Well-Known Member
Did you measure the CG with motor installed?
John Taylor
Well-Known Member
Measure with EVERYthing installed, including motor as if it is ready to carry to the pad.
John Taylor
Well-Known Member
Besides, 3 calipers is not way over stable. A lot depends on wind and speed off the rod or rail. With
less wind and more speed the overstability issue will matter less.
less wind and more speed the overstability issue will matter less.
Lukun7
Young Rocketeer
No, it was without the motor.
I don't know what i was thinking, I meant the White Thunder H225.
Lukun7
Young Rocketeer
Oh, wow, the H225 actually sims to 2175 feet and the G115 to 1056. hmm... I guess i'll listen to those instead of my earlier simulations that I did with a different, less modified file.
John Taylor
Well-Known Member
Get me an accurate dry weight (everything except motor) and I'll sim it out for you.
Nytrunner
Pop lugs, not drugs
A simulation downloaded from the internet wont reflect the final rocket that you build. Going back and adjusting it to match the weights and balance of your rocket is a necessary quality step.
Lukun7
Young Rocketeer
guys, I know how to make a simulation for my rocket. I can do it myself today once I have the rocket painted.
Nytrunner
Pop lugs, not drugs
Edit: misread last post
Lukun7
Young Rocketeer
Paint is finished!
I am so excited to fly it tomorrow!
I am so excited to fly it tomorrow!
rocketberger
Launch Director, Spaceport America Cup
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- Jan 6, 2013
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Weather is not looking too pretty. High winds but they're blowing down the runway which is good. Make sure to wear jungle type gear in case you have to go into the bush to find and recover your rocket. Watch all of the other rockets fly and remember, you don't have to fly this month. I'd rather wait a month than risk losing your rocket. Boots or tennis shoes, long pants like blue jeans, and gloves in case you have to climb a fence or a tree. See you tomorrow - Andy Berger
Lukun7
Young Rocketeer
Glad you saw this here! If I just want to test the rocket I may do the G115-7 to 1k feet. See you there! Also, What are you thinking about the build?
jjwb22101
Flying on a student budget
- Joined
- Jun 7, 2014
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Looks like a well-built and well thought-out rocket! A word of caution though - since the G115 has over 80N of average thrust it's in a weird gray area between LPR and HPR, where it requires an L1 cert to fly, but can't be used for an L1 attempt. If you can, I'd probably recommend looking into getting a 38-29 adapter (the Aeropack one is excellent, requires no assembly, and nests perfectly with their retainers) and flying it on something smaller than the H225 for your Jr L1 - something in either CTI or Aerotech's 29mm 3 grain cases (which is the 29-180 case for AT). The H128 is probably the most commonly used L1 cert motor out there, but any of them will do fine in that rocket (except the H54 - it's a bit low thrust) - judging from experience, you're probably looking at somewhere in the 1,000'-1,200' range for any of those. If you don't have access to that hardware, but you're allowed to fly sparkies at your field (I don't know Tripoli Houston's rules), the H115 is a DMS motor that's also a great option.
Lukun7
Young Rocketeer
Thanks, but I'm flying today, already have the 5438 adapter, and a 38 drill... So it seems like I should try to use a Pro38 motor for the best cost.
Do I have to have a special drill for DMS motord too? (like the I65)
Do I have to have a special drill for DMS motord too? (like the I65)
Lukun7
Young Rocketeer
Ok, good news and bad news. Good news is I acee the exam. Bae news is there were like 5 cars at the launch and is was super windy and cold, so I did not fly it. The only launch I did was my star orbiter, which weathercocked A LOT and then got banged up on the gravel. So, Next month for the cert flight.
Sorry to hear that, but you made a good call by waiting on your cert flight.
jjwb22101
Flying on a student budget
- Joined
- Jun 7, 2014
- Messages
- 147
- Reaction score
- 86
The discipline of knowing when not to fly is important - good choice waiting, and I hope the cert flight goes well when you have favorable weather to fly!
Lukun7
Young Rocketeer
Next saturday I try again. So far weather looks good.
Brian-Tampa
Active Member
I laughed so hard when I saw the paint job on your EZI-65
I looks very familiar to me. LOL
Rustoleum Orange and Gloss Black rattle cans
I guess great minds think alike
Here's mine:
Attachments
Lukun7
Young Rocketeer
Yay, we had a successful launch yesterday and I got my l1! There was a little wind and the rocket flew over the fence into the bushes, but thanks to my mentor we had a tracker! It helped a lot.
Brian-Tampa
Active Member
One note on folding and taping the shock cord. Have both ends exiting the tape in the same direction. If you don't sometimes the tape doesn't rip.
Lukun7
Young Rocketeer
I have never taped my shock cords. Does it help that much that I should?
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