help a brother out?

got a few questions as I get to the end of my EZ-I65 build.

center of gravity.....how is this affecting my launch and what do I do with this info?
center of pressure..... same as above
do I need to buy Rocksim or an equivalent before launching?
how do I determine what engine to use?
I am using dual deployment, how do I size the drone chute?


on launch day, what are my limitations to stay legal? I plan to fire it off in a private field in rural georgia

since I am making my own launch pad,where can I buy the "launch rail" that my rail buttons will ride along?

I looked on Amazon for "rocketeering for dummies" and did not find it. sorry if these are stupid questions, but I have to learn some where

Thanks in advance!

If it weighs more than 1500grams (3.3lbs) or has more than 62.5 grams of propellant or more than 80ns of maximum thrust it will require an FAA waiver (hopefully I got all the numbers correct from memory). 1010 rails (most common) can be ordered from Amazon, Grainger, McMaster-Carr, Fastenal, however Amazon seems to have the best prices on them for shipping.

Edit: I was off on the propellant weight, and average thrust and total impulse, see Bob Krech's post below for correct info, my bad (memory)

First, I suggest you find a local club to help you with your questions.
How much low power experience do you have?

You can find a lot of information in the Handbook of Model Rocketry

https://www.amazon.com/Handbook-Model-Rocketry-7th-Official/dp/0471472425/ref=sr_1_1?s=books&ie=UTF8&qid=1453058966&sr=1-1&keywords=handbook+of+model+rocketry

For a rocket to be stable the Center of Gravity (where it balances fully loaded with engine and parachute) has to be at least 1 caliber (diameter of the body tube) ahead of the center of pressure (where it balances in an airstream)

Instead of buying Rocksim you can download Open Rocket for free

https://openrocket.sourceforge.net/

Actually, to stay "legal" you can't fly anything over a G motor without getting a level 1 certification. Check out NAR

https://www.nar.org/

great info! Thank you!

is this the rail I need?
https://www.amazon.com/gp/product/B001F0K4KA/?tag=skimlinks_replacement-20

again, thanks for the help!

Thank you, Les

I did the Estes with the kids years ago, no other experience....

thank you for the link on the handbook, I really appreciate that! that looks like the basic info I needed

I joined SOAR this past month, looking forward to the meetings. going to a launch next weekend 2.5 hours south where the do up to G rockets I believe. looking forward to picking a few brains.

Again, I appreciate you taking the time to help me. I want to do this the right way, the safest way and the way that will get me that rocket back intact to fly again

hvac4u said:

great info! Thank you!

is this the rail I need?View attachment 280057
https://www.amazon.com/gp/product/B001F0K4KA/?tag=skimlinks_replacement-20

again, thanks for the help!

Click to expand...

Yes, that is a 1010 rail, and it will be good for nearly all L1, L2, and some L3 rockets (basically under 20lbs), depending on how its mounted.

Definitely find a club, as your location doesn't show up we can't recommend any clubs to you. Clubs are great because they already have all the GSE (ground support equipment) so you can just bring your rocket and fly, the club members are usually very affable types who a more than willing to help someone new to rocketry or new to its various stages, Mid Power, High Power, etc. I enjoy my membership in my club even though we are small we have a lot of fun and do a lot of work.

Thank you sir!

hvac4u said:

I joined SOAR this past month, looking forward to the meetings. going to a launch next weekend 2.5 hours south where the do up to G rockets I believe. looking forward to picking a few brains.

Click to expand...

If you can get there early they would probably appreciate help in setting up the launch equipment. That has always been one of the main complaints in the clubs I belong to; the same people usually are the ones who set up and tear down at every launch. So helping out would be a great way to introduce yourself. They would probably help you and answer all your questions anyway, but they will probably be even more helpful to someone who chips in and helps with the grunt work.

Regarding which motor to choose, I would go in style and select the very motor the EZ-I65 was designed for, the single use I-65 White Lightning:

[video=youtube;IAxqRKT4TEc]https://www.youtube.com/watch?v=IAxqRKT4TEc[/video]

And yes, the video is of a LOC EZ-I65 kit.

pyrobob said:

Regarding which motor to choose, I would go in style and select the very motor the EZ-I65 was designed for, the single use I-65 White Lightning:

[video=youtube;IAxqRKT4TEc]https://www.youtube.com/watch?v=IAxqRKT4TEc[/video]

And yes, the video is of a LOC EZ-I65 kit.

Click to expand...

...well, he is limited to a G. If he's lucky he might be able to find a 1 grain 38mm G load of some kind, a G138 for instance. I know about the needing a high power cert to load one of these, I'm sure there will be some there to help out. A G80-4 Blue Thunder SU could do it depending on the weight of the EZI65. It's fairly light but 3" in diameter, isn't it? It should come in under the weight limit depending on how stout it was built.

Bob, first foray into high power and you recommend an I65? Dude? With all due respect you might want to rethink that. Unless I missed something somewhere. And flying alone? Hmmmm...

There is nothing you can legally fly an EZI65 with that would not require a waiver.

Nice looking rocket! Welcome back to the hobby! And as usual, condolences to your wallet...

My advice is, find a club (you probably will have to drive a couple of hours), hang out, socialize, soak it all in. When you have some questions in the middle of the week/late at night, post them here. Launch some smaller rockets to prep for the Level I and to "scratch that itch" while waiting to launch that big awesome rocket. And then when you get the Level I, launch all you can.

On a somewhat related topic, I just listened to the a model rocket podcast -- the Rocketry Show at https://www.therocketryshow.com/the-rocketry-show-s2-episode-7-paint-cans-and-rocket-motors/

...and was wondering, what else can we do to help grow the hobby? There are obviously people out there like Mr. hvac4u who have a will and a desire, and some background experience and knowledge, but seem to get missed by any rocketry outreach (do we do any outreach? I guess we basically rely on kids getting hooked young, and then coming back later as adults...kinda sounds like we are a bad disease, like shingles or something...)

Okay okay, I read this and stopped reading...

hvac4u said:

got a few questions as I get to the end of my EZ-I65 build.

center of gravity.....how is this affecting my launch and what do I do with this info?
center of pressure..... same as above
do I need to buy Rocksim or an equivalent before launching?
how do I determine what engine to use?

Click to expand...

So yeah, without attempting to certify with a local club you're best bet is probably a G80-4, maybe G80-7. I've flown many in a similarly sized NCR Patriot, also 4" cardboard with good results. This is a little beefier though so a shorter delay might be in order.

If you're able, I'd join and attend a local club launch. Much more 'flexibility' .

HVAC4U

1 thing you might consider is on the altimeter sled . Instead of mounting the electronics and the battery on the same side would be to mount the battery on the opposite side from the electronics themselves. That way if something major happens and you have the rocket come in ballistic and crash the battery wont slide forward and strip all of the components off of the altimeter component board .

Bobby

I recommend you find a local rocket club.

The NAR clubs are found at https://www.nar.org/find-a-local-club/nar-club-locator/ and the Tripoli Clubs are found at https://www.tripoli.org/Prefectures/mapID/5

Most clubs have launch equipment and all have knowledgeable people.

To fly your rocket legally without a waiver or high power certification, the rocket can not weigh more than 1500 grams on the pad to be a class 1 rocket which does not require a written FAA waiver. You can not have more than 160 ns total impulse in any one motor (Full G), and the average thrust of any motor can not exceed 80 Ns. The total propellant mass in all motors can not exceed 125 grams to satisfy both FAA and high power restrictions. https://www.nar.org/find-a-local-club/section-guidebook/laws-regulations/ list the legal requirements.

Bob

bobby_hamill said:

HVAC4U

1 thing you might consider is on the altimeter sled . Instead of mounting the electronics and the battery on the same side would be to mount the battery on the opposite side from the electronics themselves. That way if something major happens and you have the rocket come in ballistic and crash the battery wont slide forward and strip all of the components off of the altimeter component board .

Bobby

Click to expand...

+1 I've seen what a loose battery can do and it ain't pretty. Some college kids at a club launch had only taped the battery in place. The battery came loose during boost, the altimeter lost power and never deployed the chutes. A very big lawn dart. I think they salvaged a fin or two, but nothing else.

Zeus-cat said:

If you can get there early they would probably appreciate help in setting up the launch equipment. That has always been one of the main complaints in the clubs I belong to; the same people usually are the ones who set up and tear down at every launch. So helping out would be a great way to introduce yourself. They would probably help you and answer all your questions anyway, but they will probably be even more helpful to someone who chips in and helps with the grunt work.

Click to expand...

great advice! thank you