3"-to-2" two stage scratch build, should fly in May

[Chad]

I'm built this smaller ( H to G ) two stage airframe to launch at my local high power club by keeping the altitude under 4k feet. I got familiar with Fusion360 and printed a number of parts. The ISC turned out really well and consisted of three separate 3d printed parts that I then bonded together. After that, I had everything I needed to attach the couplers to complete the ISC. I also 3d printed the ebays with the sustainer ebay being in the nosecone. One really interesting thing i can't wait to try out is a removable/reusable motor mount I came up with. If it works then no more permanently attaching centering rings, mmts, and expensive motor retainers.

Sustainer electronics are an Altus Metrum EasyMini, EasyTimer, and a Featherweight GPS. The sustainer is responsible for motor ignition based on the EasyTimer with tilt lockout enabled. I had to add a connector between it and the igniter so the wires can disconnect when the recovery charge is fired and the nosecone separates. I plan to add a chute release to handle main deployment. Booster electronics is a Raven and is responsible for stage separation and booster recovery. The booster is single deployment and will come down on a rocketman streamer. No GPS on the booster but it should stay within site and the streamer is pretty big. Both sustainer and booster will use the standard motor ejection charge as recovery backups.

Next thing to do is electronics config and then ground testing. First launch should be in early May ( fingers crossed, May weather is unpredictable in Texas ). The plan is to launch this airframe as much as possible to gain experience with two stage flights and then make something crazy for the larger events ( AirFest/Balls etc ).

edit: sustainer body tube is LOC cardboard, booster is PML phenolic ( i've never used that material before so wanted to give it a shot ). Surface mount 1/8" ply fins with good sized rocketpoxy fillets on both.

 

[bad_idea]

Looks great, Chad. I look forward to seeing it fly.

Questions:

• What connector did you use to break the igniter connection upon ejection? I've been thinking of using a magnetic connector like Mac laptops used to use and a bunch of cheap Chinese gadgets use nowadays.
• Are you using a separation charge? Edit: I see now you mention booster handing separation.

 

[Chad]

Looks great, Chad. I look forward to seeing it fly.

Questions:

• What connector did you use to break the igniter connection upon ejection? I've been thinking of using a magnetic connector like Mac laptops used to use and a bunch of cheap Chinese gadgets use nowadays.
• Are you using a separation charge? Edit: I see now you mention booster handing separation.

I have a bunch of breadboard wires with male and female connectors so i used a couple of those. They hold pretty tight and there's no latch or anything on the plastic so you they can pull straight apart easily. You do have to watch them carefully though and adjust the crimping if they get too loose. A magnet would work pretty well I bet and you don't have to worry about it wearing out as much.

 

[waltr]

It does look great and looking forward to updates and launch report.

 

[Sooner Boomer]

Status?

 

[Chad]

Status?

Electronics config and ground testing for this weekend.

Flying at the TNT Texas Shootout over Memorial Day weekend weather permitting.

 

[Sooner Boomer]

Looking forward to seeing it!

 

[Chad]

Launched the full rocket twice. The first one without the sustainer igniter connected went a-ok, the second launch with the sustainer ignitor connected failed to light the second stage. Originally i thought it was because the criteria required for sustainer ignition configured in the EasyTimer wasn't met but there are no data files on the EasyTimer. My best guess is launch was never detected, when i got it home i noticed the ground wire was loose but I listened for correct beeps on the pad with every launch. Maybe it lost power under thrust i'll try it again.

I also launched the sustainer by itself on a G80. It went instantly out of site and was almost lost as my GPS battery died on the pad but the West Texas Rocketry guys found it and brought it home thankfully. Because of the wind (and soft ground) I used single deployment with a 12" drogue, the altimeter reported an altitude of only 2k feet but it still drifted over a mile. From now on, i'm writing my cell number on all my airframes.

(the picture is from the TNT facebook group)

 

[waltr]

Well successful failures.
I take it the sustainer recovery worked even when the motor ignition did not.
That is success.

 

[Chad]

Well successful failures.
I take it the sustainer recovery worked even when the motor ignition did not.
That is success.

Yeah recovery went fine. Here's a picture from the TNT facebook of what I think is flight #2 coming down. Booster is on the left with the streamer and sustainer is on the right. The ISC is still attached to the sustainer so it never drag separated. I was originally planning to have a separation charge but went with drag separation first to see how it goes, i guess this confirms the separation charge is needed for the next flights. It's impossible for me to look straight up due to a form of arthritis so i rarely see rocket launches start to finish.

 

[waltr]

Good photo of the recovery.

I'll be doing the third flight of my 2-stage next weekend.
1st went well but 2nd had a very long delay getting the sustainer lit (igniter fired on time) so the rocket had arced over before sustainer got going and it power down through a tree. the booster did separate and recovery on its chute.
All repaired and ready to try again.

These are fun but so many more things to go wrong...

 

[Charles_McG]

I’ve never gotten drag separation to work on purpose. I back it up with a tiny separation charge. I fill the little plastic protector on the ematch with BP and cover it with blue tape. Works nicely.

 

[Sandy H.]

[snip] It's impossible for me to look straight up due to a form of arthritis so i rarely see rocket launches start to finish.

A few years ago, a club member did something brilliant, IMO. He had a typical old school lawn/pool lounger - the kind that you change the back-rest angle of. He would set it to maybe 20-30 deg from flat and sit up when the rocket launched and lay back as the rocket went higher. His goal was steady video footage, but I tried it a few times and it really helps keep your neck from binding up as the day goes on.

Not sure if it would be a helpful technique for you or not, but I hope mentioning it might help in some way.

Sandy.

 

[Ronz Rocketz]

A few years ago, a club member did something brilliant, IMO. He had a typical old school lawn/pool lounger - the kind that you change the back-rest angle of. He would set it to maybe 20-30 deg from flat and sit up when the rocket launched and lay back as the rocket went higher. His goal was steady video footage, but I tried it a few times and it really helps keep your neck from binding up as the day goes on.

Not sure if it would be a helpful technique for you or not, but I hope mentioning it might help in some way.

Sandy.

On those low wind days over 500ft, my chiropractor complains. I have a beach chair but getting out of it is less than dignified. I’ll give it a try. Nothing but wind for the foreseeable future.

 

[gdjsky01]

Do you happen to have the files for your 3D parts?

 

[Chad]

Do you happen to have the files for your 3D parts?

To make the isc there's actually three parts that get bonded together. Because of the way the shapes turned out it can't be printed all at once. I wish I had taken photos of putting it together...

I'll try to explain it here
1. print all three parts
2. the connector part get bonded into the top centering ring which creates a little ridge on top for the reducer to connect to
3. the reducer then bonds onto the top centering ring with the connector keeping it aligned

if it doesn't make sense let me know and i'll post some screenshots from fusion 360

EDIT: or i can just make you one and send it to you, you can pm me and we can set it up