L3 Project beginnings

The general design is in my head - imagine a 4x Estes Ventris standing 12 feet tall with a 10" diameter payload bay and you get the picture.

In preparation for the build, the collection of big ticket items has begun. As this is a project with a strict budget, finding necessary items at a good price can take time. First came the used 75/5120 RMS picked up from a local dealer. Then an M1297 from a Black Saturday sale. Next came a used 75mm motor retainer and 144" Spherachute from the TRF Yard Sale.

So, with about $550 in the project so far, here is what there is to show for it :eyeroll:. It's like an invisible body where you can see the innards.

I won't buy a nosecone or birch plywood or Sonotube until I have the appropriate go-ahead on the design from an experienced NAR L3CC member or TRA TAP. If folks are interested, I'll keep this thread going as things progress.

Where this may vary from the norm is that there will be provision for four booster motors between the fins. So after the cert flight, if all goes well, the next flight will be with an L900 Dark Matter and maybe four H115s to boot. That would be lots of sparks at once!

Sounds like a plan. Looking forward to your build thread. I'm starting the L3 process soon myself.

Slow progress is much more than zero progress! Keep it rolling, keep sharing, and keep learning along the way!

This is great. You have the chute, motor and hardware. I have everything for my L3 except the chute, motor and hardware. Between us we have a L3 project.

Good luck with your project, I like a scratch built cert rocket. Your L3CC member or TAP(s) will be valuable help, if for no other reason than you are going to have to think through everything really well.

Oh, you used that off brand Clear paint... I know how that can be.

Good luck on the project/Cert! op:

If the decision is to go with Sonotube, what's the opinion on having to wrap it in fiberglass?

The plan is to have an internal rigid structure made up of 1/4" birch ply centering rings and four equally spaced 3/4" square longerons bonded to the booster and payload tubes. Is that enough for strength and rigidity?

This will be a big heavy bird that is intended to fly well below Mach.

The plan for a one-off custom project continues to be enticing, but a year later the thought of a simpler project using an existing kit capable of handling an M motor has won out. It started out with a little suggestion to Mike at Madcow to offer the 4" 75mm fiberglass series for one of the Hump Day sales. I promised if the deal was right, he could put me down for a Tomach. True to my word, I snatched one when Madcow answered recently with exactly what I was hoping for.

View attachment 305481
Waiting on the doorstep, hot off the USPS truck was this box of goodness.

View attachment 305480
The invoice and two additional chute protectors were sitting right on top.

View attachment 305479
Event though there are several projects in front of this one, I couldn't resist inspecting and dry fitting the parts to get a sense of what is coming.

So now to design the internals and come up with a build plan to run by a TAP for approval. A progression of Aerotech motors are already picked out to test out functionality and electronics at low enough altitude to see it all happen. First motor (with a 75mm-54mm adapter) will be a K805 Green in a 54/1280 case that sims to 4,300 feet. Then we will move up to the 75/5120 case starting with a 75mm K780 Red using two spacers to get used to using the bigger diameter case. That should top out at 5,500 feet. Then the L3 attempt on an M1297 White to just over 12,000 feet. There is an L900 Dark Matter in reserve that will take it to 9,100 feet to celebrate getting the L3 with an awesome pyrotechnic show.

That will be a great rocket - look forward to the build. As you were mentioning before the 4x Ventris 10"x12' I was thinking, I hope that is built light for the motor you have! But now not an issue.

But you definitely owe the forum that Ventris upscale now.

Best of luck with your builds!