My L2 Project

[OverTheTop]

There is a minimum distance behind the nosecone for a static vent. Not sure what it is without looking it up. I'll leave that to you. The nosecone creates a wake vacuum immediately behind it.

from Verns page "They should also be well away from the nosecone joint or any other transitions in the body diameter since these can cause turbulence and either increased or decreased pressure regions.

It depends on the electronics as to how it handles the turbulence too. Personally I run a TeleMega in the NC and the vents are about 0.3 calibers below the NC curve. No problems with that setup for me.

 

[bobbyg23]

I have 1 of my altimeters in my nose cone so the vent hols are on the curve and it works just fine.

 

[OzHybrid]

And the manufacturer of the electronics recommendations are...? Nothing in the manual. doesn't get a mention. The only way you can know if it's an issue is to launch it. Then it's a bit late.
Ask Adrian.

 

[thzero]

There is a minimum distance behind the nosecone for a static vent. Not sure what it is without looking it up. I'll leave that to you. The nosecone creates a wake vacuum immediately behind it.
Norm

Yes, fully aware. This is head in dual deployment; the nose cone has a good 4" where its pretty much straight up and down with very little if any curve in it. Basically where the smudge mark line that can be seen in the picture; that was basically from being inverted in a body tube.

Do need to do some more smoothly and joint work.

 

[thzero]

Ok... added some plates for the shear pins.

 

[thzero]

I'll have to remember to take a photo or two tomorrow, but I've had good luck with the fins and vacuum bagging with just a standard food saver. First couple of attempts have had excess epoxy, however I've found that bleeder cloth as well as release cloth seem to work wonders and I have little if any extra epoxy getting on the backside of the fins.

I also plan on putting a layer of fiberglass over the leading and trailing edges. I was trying to figure out how to get the fiberglass to fold and lay down without a struggle, same with release cloth. Then it dawned on me... heat! Why not just use an older iron and not on too high of heat setting (using polyester setting) iron a crease into the fiberglass cloth and release cloth. Sure enough, it works... got a nice crease, so now the cloths can just drape over the leading/trailing edge and get vacuum bagged!

 

[thzero]

Ok, so the fins are done! There is minor amount of cosmetic work to finalize, but overall the mechanical parts are done. Amazingly, I think that makes the rocket mechanically feature complete!!







Now just need some better weather so can do some ejection charge testing!

 

[thzero]

Not much right now. Got some primer on the tube and nose cone. Then some more filler. Waiting for weather to get a tad nicer to go sand again and re-primer.
Need to do some filler on the fins a bit and then same.

 

[thzero]

Just in primer... so now can go do some ejection testing.

 

[OzHybrid]

So you've printed the fins and then glassed them? What did the weight end up per fin?

 

[thzero]

So you've printed the fins and then glassed them? What did the weight end up per fin?

Yes.
Looks like my measurements are

3D printed fin - 3.31oz
Fiberglassed fin - 4.13oz

 

[thzero]

Got the camera mount for the Mobius Mini video camera (https://www.mobius-cam.com/en/mobiu...lens-a-p-146?zenid=283olnmfkj7pgfo2asrmlb4ab7) and attached to the rocket tube.




Here is a view of the 3d printed mount prior to using epoxy to smooth it out.



Then the mounting bracket, also 3d printed, that holds two t-nuts for the mounting screws to tie into.




And finished with epoxy for smoothness, as well as sprayed with high temp black paint.

 

[thzero]

So got the ground testing done yesterday; didn't get video as with the Eggtimer Quantum being used to fire the test I didn't think to bring the same phone to do the recording with. Nonetheless had some L2 club members around, and got some feedback from them.

Here are the measurements I had worked out using various calculators for the BP amounts

drogue bay 6.75" length x 5.415" inside diameter

• 15psi, 1.2g

main bay 8.965" length x 3.386" top inside diameter and 5.415" base inside diameter; 4.4005 avg diameter

• 15psi, 0.63g top diameter
• 15psi, 1.6g base diameter
• 15psi, 1.06g avg diameter
• 15psi, 1.115g avg of top and base bp

And then testing...

drogue

• 1.75g test - unfortunately it ended up being closer to 1.9g, but the test gave a good result
• Planned Usage
  • 2g primary altimeter charge
  • 2.5 secondary altimeter charge

main

• 1.5g test - did not give a good pop
• 1.75g test - gave a nice solid separation
• Planned Usage
  • 1.7g altimeter primary
  • 2.25g altimeter secondary

Did end up popping off one of the shear pin steel plates, but that was due to a poor epoxy job on my part. That is being resolved right now, otherwise the shear pin steel plates worked well. The shear pins did cut clean. The only real downside is they are a bit harder to remove from the avbay,, since the steel plates are threaded, without either punching them through (which makes me cringe) or taking apart avbay and unscrewing them from inside.

 

[waltr]

I also have found needing a bit more BP than calculated. Good reason to ground test.

I use t an Xacto knife #11 blade and push to point into the nylon screw. Then turn the screw inwards until free.
The small piece of nylon can stay inside the AVbay until next time it is opened.

 

[BDB]

I'm just reading this thread for the first time now. It's fantastic! love the blend of 3D printing with conventional techniques.

 

[thzero]

I also have found needing a bit more BP than calculated. Good reason to ground test.

I use t an Xacto knife #11 blade and push to point into the nylon screw. Then turn the screw inwards until free.
The small piece of nylon can stay inside the AVbay until next time it is opened.

I tried a Swiss army knife blade point that I had, no go. May need to pack an xacto and see if that works better.

 

[thzero]

Color coding the wiring; this is my standard dual deploy system with two altimeters for using with 3"+ rockets...



And all hooked up in the 5.5" mount...

 

[thzero]

I use boxes to keep parts, avbays, eletronics, camera mounts, etc. together for different types of rockets. Started using the boxes that used to come with the 3d printed spools. Makes for a handy way to keep track of a rockets "extras".

 

[thzero]

Ended up putting a small vent hole in the body to make it easier to slide in the altimeter bay when motor is loaded.

Also have gone back and carefully twisted all the wires with the electronics. That question from L2 keeps popping in my head...and looks cleaner too boot

 

[thzero]

Well, looking forward to hopefully the Level 2 launch next month. Passed the written test today, so happy about getting that behind me.

 

[Hobie1dog]

Thanks for all the pictures Good luck on the launch.

 

[tsmith1315]

Well, looking forward to hopefully the Level 2 launch next month. Passed the written test today, so happy about getting that behind me.

Good luck with that flight!

 

[thzero]

Well, good news, bad news to report here.

Bad news? This rocket was not used for my L2 certification flight!

Good news? The rocket flew and was recovered successfully at Midwest Power over the weekend. I'll post videos, but the up part went well, the down part with DD went well (although erred too much even with ground testing on BP amounts) on the two events, however I must have not packed the main in the deployment bag correctly because it did not really deploy. However, rocket was fine due even if one fin certain plowed a line in the soft dirt at the farm MWP launches at. Obviously need to review some of the deployment bag packing and get in some more practice with it.

The I284 flight was at 1400 or so feet. I'll be posting some pictures. video and altimeter readings later.

 

[thzero]

Assembly...



Finished fin assembly...



On the pad... sorta forgot to take a closer shot before leaving pad area.



Google Earth flight path...



Flight info...

 

[thzero]

And a video for the launch....

 

[cwbullet]

Warlock is a great low and slow bird. Very nice flight. Congrats.

 

[loopy]

so...when does it get a J?

 

[thzero]

so...when does it get a J?

Hoping to get some for BF sales...

 

[thzero]

Well, it's finally got a paint job.

Assuming the weather holds at Midwest Power this weekend it'll got back up on a J350.

 

[OverTheTop]

Good luck with the weather and certification .