First dual redundant Av bay is done.

The Rocketry Forum

Help Support The Rocketry Forum:

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
I hope it works. Tracker in the nose, dual EasyMini's for the drogue and main. You can't see the back side but there are dual 350Ah Lipo's for each EasyMini. So redundant batteries too. Only one mag switch for each EasyMini. I could have used a screw switch on one battery and and the mag switch on the other but I was already past overkill. This is going in a LOC IV (My L1 cert rocket) which has been my "practice rocket for this entire year. It's been fun modifying it. I'll find out tomorrow if I made an expensive lawn dart or have a successful flight. I'm still debating on I350 or I540 motor and I still need to weigh it, check the Cg, check the sim, assemble, etc.

 
Last edited:

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
Interesting use of expended shell casings as ejection charge canisters never seen it before.
I got the idea from one of the guys here in the club. .40 cal is on the edge of being too small.
 
Last edited:

teepot

Well-Known Member
TRF Supporter
Joined
Dec 8, 2019
Messages
1,836
Reaction score
1,427
Location
Pahrump, Nevada
I've used .45 long colt cases, 7.62 x 39mm and 30.06. .45acp is too small. I cut the rifle brass just below the neck with a Dremel and a cut off wheel.
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
I've used .45 long colt cases, 7.62 x 39mm and 30.06. .45acp is too small. I cut the rifle brass just below the neck with a Dremel and a cut off wheel.
I've got perfectly good commercial cannisters. I just didn't feel like changing. The next rocket is fiberglass. I'll do something different then
 

Wayco

Desert Rat Rocketeer
TRF Lifetime Supporter
Joined
Mar 23, 2011
Messages
3,724
Reaction score
777
Location
Goodyear, AZ
I've used shell casings in several smaller avbays. Just be careful how you route your e-match leads, the edges of the casings are sharp enough to short them out under thrust.
 

OverTheTop

Well-Known Member
TRF Supporter
Joined
Jul 10, 2007
Messages
5,915
Reaction score
3,449
Location
Melbourne Australia
I put a small piece of heatshrink tubing on the back end of all my eMatches to make sure they don't short on anything. Yes, you can shrink that safely with a heat gun, but be gentle and wear the necessary PPE.
 

Philip Tiberius D.

Old Fashioned 2.5oz Rye/H2O 8 drops Orange Bitters
TRF Supporter
Joined
Oct 17, 2018
Messages
324
Reaction score
170
Location
Bixby, OK
I think BadAss Rocketry sends shell casings with their deployment kit… at least that’s what a club member here said, I’ve ordered one so I’ll find out. I guess the reason a small hole is not drilled in the base of the charge holder and the E-match inserted there is once done you have an active assembly?
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
I think BadAss Rocketry sends shell casings with their deployment kit… at least that’s what a club member here said, I’ve ordered one so I’ll find out. I guess the reason a small hole is not drilled in the base of the charge holder and the E-match inserted there is once done you have an active assembly?
I left the spent primer in the case. I was told that you don't want to have a hole for the hot gas to get into the AV Bay.

I looped them up and over , clearing the rim of the case by at least a quarter of an inch. Good launch today. We had a 3 good flights today. Two (one L3 and one L2) had apogees on the 24k / 25k range. We had our first COA to 50,000 AGL but it didn't come soon enough for our L3 guy to make a motor. The next one is 6/4/22.

For the third time there was a loud pop after liftoff. Loud enough that the more senior fliers thought the motor CATO'd. It didn't but when I pulled the liner out of the case it was burnt up worse than usual. No damage to the case,





Launch. Cessaroni I540



The winds were calm or nearly so. Straight up.



On the main. The flight wasn't flawless. Prior to launch we discussed adding tape to the upper nosecone section since it came out about a 1/2" with no effort but then firmed up. The thinking was that the inertia of the rocket slowing down at apogee might cause the nosecone to come out. I elected to "try it". For me this is all about learning what happens when "little things" aren't right. The main coming out after the drogue and before 800' AGL just increased the wait time. But I will fix it before the next launch. The nosecone came out and pulled the main after after apogee. I'm not sure when. I have some photos after apogee and the nosecone was still attached. I know the charges didn't fire early because they fired right on time later.



Less than 40 yards from the launch rail :)



All laid out and ready to pack



Track. The darker blue line is when I picked it up. I forgot to shut the tracker and altimeters off.


Stats from the Telemetrum 3.0 in the nosecone.



Graph. The boxy looking green line is GPS height (I was curious)

 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
That's a good point. More reason to switch to a different charge cannister.
 

Wayco

Desert Rat Rocketeer
TRF Lifetime Supporter
Joined
Mar 23, 2011
Messages
3,724
Reaction score
777
Location
Goodyear, AZ
Congratulations on your first DD flight. I took a bunch of pics when I did that with a LOC Nuke pro max, it's really exciting when you get it right the first time.
Most of my DD rockets use Doghouse charge cups:
http://binderdesign.com/store/charge-wells.html

Looking at your avbay sled, I didn't recognize the magnetic switches. What are you using and where did you get them?
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
Congratulations on your first DD flight. I took a bunch of pics when I did that with a LOC Nuke pro max, it's really exciting when you get it right the first time.
Most of my DD rockets use Doghouse charge cups:
http://binderdesign.com/store/charge-wells.html

Looking at your avbay sled, I didn't recognize the magnetic switches. What are you using and where did you get them?
Doghouse charge cups - that's what bought (and forgot I had).

Featherweight Altimiters - https://www.featherweightaltimeters.com/store/p4/Magnetic_Switch.html

One day I wouldn't mind integrating Hall Effect sensor into the power board but I'm on the fence. With the Featherweight switches I can put them where I want them and have flexibility for mounting things. I 3D printed the "enclosure. It's a tight fit and it snaps in. I use a spot of hot glue to make sure it stays put. Not much to it but it works
 

Attachments

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
I suppose, since my info says Weimar, TX, I should point out that I'm not launching in TX. I fly with, and am member of, the Four Corners Rocketry Association out of Farmington, NM. Launch site is south of Bloomfield, NM.
 

Wayco

Desert Rat Rocketeer
TRF Lifetime Supporter
Joined
Mar 23, 2011
Messages
3,724
Reaction score
777
Location
Goodyear, AZ
Thanks for the info. It was the printed enclosure that caught me out. I use FW magnetic switches in many of my DD rockets, and I have a lot of them.
I mount mine directly on the sled, with a small 4-40 screw through the ground hole to hold it in place:

sled detail.jpg

Hot glue to provide strain relief on the wires. This sled is in a 4" Wildman "Big Bad dog" I'm currently building.

I'm also going to look up the Four Corners Rocketry Association. We spent last summer in Red River, NM. and visited several clubs in Colorado. Always looking for a good place to fly rockets.
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
Thanks for the info. It was the printed enclosure that caught me out. I use FW magnetic switches in many of my DD rockets, and I have a lot of them.
I mount mine directly on the sled, with a small 4-40 screw through the ground hole to hold it in place:

View attachment 484246
Hot glue to provide strain relief on the wires. This sled is in a 4" Wildman "Big Bad dog" I'm currently building.

I'm also going to look up the Four Corners Rocketry Association. We spent last summer in Red River, NM. and visited several clubs in Colorado. Always looking for a good place to fly rockets.
Nice sled! I put them in the enclosure and set them back far enough so they'll clear the tube (early lesson). In the vertical position I can see the LED on the switch through the vent hole. Besides... 3D printers seem to want a lot of attention. I print things just for the sake of trying to learn Fusion 360 sometimes.

Come on over. We typically launch the first Saturday of each month unless the weather "person" misses the forecast, like this weekend, and the launch date is moved. My sig has a clickable link for the site. It's a small club. Today there were 3 members launching and 4 guests watching. It was a much bigger crowd than usual lol. Sometimes the college in Durango comes out as well. November is our last launch until spring. I think Mar 21? I'd have to check
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
Here's a question for the masses - I remember reading something about where to put the equalization holes in the nosecone. Too high up (on the curvy bits) and it could jack with the pressure altimeter by pulling the nose cone low (pressure). It wouldn't take much pressure change to make the altimeter think it's higher.

This is the nosecone. I put two holes in it. One lines up with the LED on the mag switch



The nosecone has the Telemetrum in it.

Sim - 4,191.96.
Telemetrum Max Ht: 5,042'
EasyMini 1 - 3,923'
EasyMini 2 - 3,926'
3,924.5 average between the EasyMini's or about 6% less than the sim. All things considered. That's not horrible.

But I'm not 100% sure the problem is the hole location. The nosecone doesn't really have a flat spot. The bulkhead in the nosecone is right there at the transition (primer to white) so I can't vent there. I don't want to equalize there anyway because the ejection charges point in that direction.
 

Michael L

Random Pixel Generator
TRF Supporter
Joined
Sep 22, 2020
Messages
419
Reaction score
315
Location
Weimar, TX
I wonder if I could plug the hole that I want to use to see the LED with a clear plastic plug (like a acrylic rod cut flush) and move the vent hole as far back as I can get it?
 

Wayco

Desert Rat Rocketeer
TRF Lifetime Supporter
Joined
Mar 23, 2011
Messages
3,724
Reaction score
777
Location
Goodyear, AZ
Are you using the holes as static ports for the Telemega, or to determine if your mag switch is on? I would just ignore the altitude reading on the Telemetrum and use the existing hole to check if power is applied to it.
You already have two Telemini's giving you accurate readings, use the Telemega for your GPS and be happy.
 
Top