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Wed, 14 Jul 2021 07:37:55 -0400

jason@hub.inktada.com

Nose cone needs final polish, but is pretty dang shiny as shown with phone screen reflection in previous post.

Airframe needs sanding with 400 grit, followed by final coat of paint, wait two days to dry, then sand with 2000 grit, followed by polishing.

It's nice to see it finally coming together. Chrome monocote detailing will be the final touch.

Window in yellow section is for video camera inside.

EZI-65 Next High Powered Rocketry

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Wed, 14 Jul 2021 07:50:05 -0400

FourOh-LLC

fouroh-llc@hubzilla.factoryfouroh.net

I know little about the science, but the nose supposed to balance the rocket? If so, do you rotate the assembly and drill to balance? I understand the shape and surface must be aerodynamic, but I have no idea how the fins I think called stablizers would be able to balance if the entire assy was not rotated-balanced.

I am nearly finished designing and proofing a 24.0" x 4.5" x 1.0" conveyor segment, for a 12' super-light-weight conveyor. Next I might build a lathe for rotation balancing, if I can collect enough practical (industrial) applications for it.

Wed, 14 Jul 2021 08:32:50 -0400

Jason Cook

jason@hub.inktada.com

Everything is in perfect alignment, meaning there is no tilt or bend to the rocket.

The nose section in this case is is extremely aerodynamic as it is a Von KÃ¡rmÃ¡n design. That means it performs extremely well subsonic, transonic, and supersonic.

Design of rockets requires that the center of gravity be in front of the center of pressure by at least 1 caliper (the diameter of the rocket). If you are going supersonic, you want at least 2 calipers as a stability margin. If you are over stable, say 4 or 5 calipers, your rocket will clock stronger into the wind direction. If your rocket is not stable enough, it will skywrite, meaning go crazy.

The center of pressure for this rocket is ~13 inches from the back.

The center of gravity for the maiden flight will be roughly 1.7 calipers in front of the center of pressure.

Balance on the vertical axis is almost always near the center of the cylinder. If it is off, I could see the rocket spiral somewhat, but it would be minimal since the overriding forces are the center of pressure and the center of gravity if you have uniform fin and nose design.

To compute all these numbers, you input your rocket design into rocketsim, openrocket, or rasaero(great for supersonic).

You then input the motor, wind direction, etc., and you get estimated altitude, drift, and all kinds of graphs to help.

Before this rocket ever gets airborne, I have to first compute the pyro to eject the main and the pyro to eject drogue chute. The computations to do so are provided here: #^https://www.insanerocketry.com/blackpowder.html

Once computed, always ground test so you know for absolute your charges will eject those chutes. You never want your rocket coming down ballistic.

Wed, 14 Jul 2021 08:44:31 -0400 last edited: Wed, 14 Jul 2021 08:45:47 -0400

Jason Cook

jason@hub.inktada.com

If you haven't launched rockets before, I recommend looking into estes rockets that you can purchase at hobby lobby. Check with your local park to see if you can launch there, some places do not allow model rockets, but because it is STEM, many do. I recommend small motors like A for your first launch. Make sure you get a launch pad, wadding, and a pack of motors.

High Powered Rocketry
If you decide at some point you want to try launching a high powered rocket, this kit is an excellent one to try #^https://www.apogeerockets.com/Rocket-Kits/Skill-Level-3-Model-Rocket-Kits/Torrent You use epoxy for all gluing to make it strong. If you have launched little rockets from estes before, you can start out by doing something similiar with no electronics. The motor launches the rocket, delays a number of seconds, and then fires the ejection charge. This kit can grow to being electronics capable very easily, so it can grow as your experience grows.

Before you launch, you need to find your local rocket club, find a mentor, join the NAR(recommended for beginners) or tripoli and someone needs to inspect your rocket prior to launch. If you launch with an H or higher motor, you must have a mentor inspect and watch your rocket launch. You are then level 1 certified.

You can find info about the NAR here: #^https://www.nar.org/
You can find info about Tripoli here: #^http://www.tripoli.org/

Wed, 14 Jul 2021 09:40:53 -0400

FourOh-LLC

fouroh-llc@hubzilla.factoryfouroh.net

I have way too many projects to get yet another one, so I pass. But I was curios if you at any point to do some sort of post-processing to balance the assy. I see you would not need any sort of lathe for this.

Wed, 14 Jul 2021 09:59:45 -0400

Jason Cook

jason@hub.inktada.com

It depends on how the parts are built on if you need a lathe. If you were building the nose out of metal or wood, or from sculpted design, you would want one to insure balance.

I know people that build their nose out of aluminum and wood, and in both cases using a lathe would seem both practical and would optimize your altitude and direction performance.

For the fins, you typically want those sculpted identical prior to installation to insure they are uniform.

For aluminum alloy body tubes and nosecones, higher end builders a solid block of aluminum alloy and it is carved to form both inside and out to insure maximum strength.

Wed, 14 Jul 2021 10:14:22 -0400

FourOh-LLC

fouroh-llc@hubzilla.factoryfouroh.net

Lathe as subtraction machining and lathe as diagnostic instrumentation are different applications. I was thinking about the later, 3D printed assemblies cannot be used for machining. So the lathe I would build would be instrumentation, rotating the piece against a base reference like a laser. In the beginning would be a simple amplified voltage or current reference, more likely.

Anyhow, later today i am going to post some photos of the conveyor segment. Its using the "instrumentation" concept, instead of using it for material transport it is going to allow designing and wiring up line automation. Because its ligh-weight you can store it hanging from the wall, like a ladder. Once the design is completed the real thing, build from metal, just plops in its place.

Something like that.

Wed, 14 Jul 2021 10:29:30 -0400

Jason Cook

jason@hub.inktada.com

If I were working with metal, I would always go to the extreme for exactness.

For what I build (including when I build from fiberglass from the ground up), there is an extreme satisfaction with using my hands to finish the rocket. In almost all cases it outperforms the computer simulated benchmarks.