First Scratch Build

[Mattgibson629]

Hello ya'll, I was able to obtain a cardboard tube that is probably 18-24 inches long and 1 1/2 inches in diameter. I am just getting back into model rocketry after a 30+ year absence and was wondering if it would be worth a try to scratch build a low power rocket. The design would be all mine and I have several thoughts on what I want. If possible I would like to use the biggest engine possible for a LPR. I have been researching websites, YouTube, this forum, and a podcast and I think it would be very possible. Any ideas and suggestions will be appreciated, even ones that think this may be a bad idea. Thank you!! Matt

 

[Nytrunner]

Welcome Matt Gibson the 629th! (That is an impressive family name history, lol)

Scratch building is a great part of this hobby!

You mention biggest motor possible for LPR. Since you've been reading the forum, i imagine you know about the hobby's informal distinction of Mid Power (E-G).

Do you want to build for a D (the hobby's "LPR"), or a G (largest that can be used without certification)?

A G in a 1.5" tube will go over 2k feet and require a huge landing area if you want to get it back. Not inpossible just needs careful planning.

Good luck and have fun!

 

[Mattgibson629]

Welcome Matt Gibson the 629th! (That is an impressive family name history, lol)

Scratch building is a great part of this hobby!

You mention biggest motor possible for LPR. Since you've been reading the forum, i imagine you know about the hobby's informal distinction of Mid Power (E-G).

Do you want to build for a D (the hobby's "LPR"), or a G (largest that can be used without certification)?

A G in a 1.5" tube will go over 2k feet and require a huge landing area if you want to get it back. Not inpossible just needs careful planning.

Good luck

Welcome Matt Gibson the 629th! (That is an impressive family name history, lol)

Scratch building is a great part of this hobby!

You mention biggest motor possible for LPR. Since you've been reading the forum, i imagine you know about the hobby's informal distinction of Mid Power (E-G).

Do you want to build for a D (the hobby's "LPR"), or a G (largest that can be used without certification)?

A G in a 1.5" tube will go over 2k

Welcome Matt Gibson the 629th! (That is an impressive family name history, lol)

Scratch building is a great part of this hobby!

You mention biggest motor possible for LPR. Since you've been reading the forum, i imagine you know about the hobby's informal distinction of Mid Power (E-G).

Do you want to build for a D (the hobby's "LPR"), or a G (largest that can be used without certification)?

A G in a 1.5" tube will go over 2k feet and require a huge landing area if you want to get it back. Not inpossible just needs careful planning.

Good luck and have fun!

Thanks for the info. I guess I need to research LPR a little more. Can I use something like that as a certification rocket?

 

[Mattgibson629]

I'm not sure why this repeated several times. This is my first post and I may be doing something wrong.

 

[Nytrunner]

Yeah, posting here takes a little learning curve.

A 29mm mount is needed for a G motor (except for a few that fit in 24mm mounts), and many H motors and a couple I's fit in 29mm also. My personal philisophy is that if you can successfully fly and recover a G rocket, getting L1 is no more trouble.

 

[Mattgibson629]

Thank you for that information. I'm going to look at that more closely. A big problem is going to be the closest club is 75 miles away.

 

[Mattgibson629]

Is there a certification for low power or only for high power rocketry?

 

[Nytrunner]

Only High power flying requires certification.

I hear you on the club distance issue. Lots of folks drive an hour or 2+ to get to waivered high power launches

 

[PatD]

From another thread and Joe Bruce who states it succinctly:
"If I understand correctly, any rocket <1500 g total weight AND <125 g propellant weight is FAA Class 1 and can be flown without an FAA waiver if >5 nm from the nearest airport. This Class 1 definition includes model rockets AND high power rockets per NFPA 112. NFPA 112 "model rocket" has the FAA Class 1 restrictions but also adds <80 N-sec avg. thrust, <160 N-sec total thrust (single motor) or <320 N-sec total thrust (multiple motors, and sparkies."
So with appropriate permission from the property owner where you are flying and appropriate distance from habitations you can fly mid power rockets without certification.

 

[tsmith1315]

Hi Matt, first welcome back to the hobby. I've been out for half that long myself.

I encourage scratch building, but there are caveats. If you're using non-standard tubing, be aware you won't be finding couplers, centering rings, nosecone, etc in a pre-made form. This means time spent making your own, or money spent having someone make them for you.

Building those items can be entertaining or tedious, depending on your perspective.

Also, you'll probably want to get software to help you predict stability in flight, if you don't have it. If you want to fly your own design at a launch, a Safety Officer will probably want to know that you verified stability before allowing it to fly. Especially if you don't have a flight history with the club.

That said, I strongly encourage you to make the 75 mile drive to a club event. For many reasons you'll be glad you did.

 

[Mattgibson629]

Hi Matt, first welcome back to the hobby. I've been out for half that long myself.

I encourage scratch building, but there are caveats. If you're using non-standard tubing, be aware you won't be finding couplers, centering rings, nosecone, etc in a pre-made form. This means time spent making your own, or money spent having someone make them for you.

Building those items can be entertaining or tedious, depending on your perspective.

Also, you'll probably want to get software to help you predict stability in flight, if you don't have it. If you want to fly your own design at a launch, a Safety Officer will probably want to know that you verified stability before allowing it to fly. Especially if you don't have a flight history with the club.

That said, I strongly encourage you to make the 75 mile drive to a club event. For many reasons you'll be glad you did.

Thank you!!

 

[Greg Furtman]

Thank you!!

Hi Matt, welcome aboard! I too am making scratch builts from cardboard tubing. I worked at a 2 year college for almost 20 years and one of the departments has a 42" HP plotter. So when a roll of paper was empty I'd keep the tube. I have a number of them in my stash.

One of the things that has helped me the most is OpenRocket. Here's a link to the package installers for Mac or Windows put together by TRF member neil_w OpenRocket is Open Source software that is Java based. Neil's installer packages also contain the Java version needed to run OR.

https://www.rocketryforum.com/threa...d-mac-to-solve-all-your-java-problems.143540/

Member K'Tesh has but together some good OpenRocket Tutorials posted here on TRF.

https://www.rocketryforum.com/threads/kteshs-openrocket-tutorials.62884/

 

[Mattgibson629]

Hi Matt, welcome aboard! I too am making scratch builts from cardboard tubing. I worked at a 2 year college for almost 20 years and one of the departments has a 42" HP plotter. So when a roll of paper was empty I'd keep the tube. I have a number of them in my stash.

One of the things that has helped me the most is OpenRocket. Here's a link to the package installers for Mac or Windows put together by TRF member neil_w OpenRocket is Open Source software that is Java based. Neil's installer packages also contain the Java version needed to run OR.

https://www.rocketryforum.com/threa...d-mac-to-solve-all-your-java-problems.143540/

Member K'Tesh has but together some good OpenRocket Tutorials posted here on TRF.

https://www.rocketryforum.com/threads/kteshs-openrocket-tutorials.62884/

Thank you!!

 

[Greg Furtman]

Thank you!!

Glad to help.

 

[Mattgibson629]

I took some measurements today and the tube is 19 inches long with an inside diameter of 1.5 inches. Is that big enough to even worry with high power?

 

[dhbarr]

I took some measurements today and the tube is 19 inches long with an inside diameter of 1.5 inches. Is that big enough to even worry with high power?

Would make a fine motor tube for a big 3-4incher. Or it could become the minimum diameter body tube for something that would accept a 3 or 4 grain reload.

However, as some folks have previously mentioned it's the components that go inside a tube that can be tricky; nosecone shoulder and centering rings are two of the biggies.

 

[BABAR]

You can certainly build it with a 29mm mount. As mentioned, likely any 29 mm motor is going to take it to an altitude where you will need a big field to get it back. But even with a 29 mm mount, you can cheaply buy or easily and even cheaper build adapters that would allow you to fly on 24 mm motors, if it is built to handle 29mm motors likely but not definitely too heavy for 18mm. This may give you the option to fly on a smaller local field (if permitted by local regs and landowners). You may need to come up with a way of adjusting nose weight, you likely will require little if any for the smaller motors, more for the larger ones. OpenRocket is likely your friend here.