New 102mm project - Chimichunga-I

[jqavins]

... and I had epic runs.

Gee, dude, sorry to hear that. These things usually pass in a day or less. Just be sure to drink plenty of fluids, and if it goes on longer then you should probably see your doctor.

 

[snrkl]

Gee, dude, sorry to hear that. These things usually pass in a day or less. Just be sure to drink plenty of fluids, and if it goes on longer then you should probably see your doctor.

[emoji13] I see what you did there... [emoji6]

 

[snrkl]

Wiring harness for the rotary switch on the switchband complete.

I gave up trying to get the molex connectors I bought crimped properly (they were horrible!) even with the correct tool, so I used some JST connectors I had left over from a previous project.

All up, it was JUST long enough so that I can disconnect it to remove the avbay sled.

 

[Andrew_ASC]

You’re doing fine Snrkl.

 

[boatgeek]

If you have enough length in your switch wiring harness, I would glue the harness to the inside of the tube. Those Schurter switches are not very tolerant of flexing the terminals. If the terminals flex when you slide the sled in, it won't take long before the terminals start breaking off.

 

[jqavins]

Those connectors have no locking mechanism if I'm seeing it right. As part of flight prep, you would be wise to tape them together, or apply a dollop of hot glue, silicone, or some other adhesive that will come off easily enough after the flight.

And I second Andrew's comment. You're doing fine to say the least.

 

[snrkl]

Those connectors have no locking mechanism if I'm seeing it right. As part of flight prep, you would be wise to tape them together, or apply a dollop of hot glue, silicone, or some other adhesive that will come off easily enough after the flight.

And I second Andrew's comment. You're doing fine to say the least.

They have locking mechanism. You can just make out the locking tang on the last pic. The clip is on the other end.

 

[snrkl]

If you have enough length in your switch wiring harness, I would glue the harness to the inside of the tube. Those Schurter switches are not very tolerant of flexing the terminals. If the terminals flex when you slide the sled in, it won't take long before the terminals start breaking off.

Yeah - I totally agree with you. What you can’t see is that I’ve soldered the wires to the switch, laid thin shrink tube over the wire and solder joint all the way up the shoulder, then added a larger shrink tube over that. The plan is to add one last layer of larger tube over the whole end. The switch is also easily unscrewed and replaced.

 

[jqavins]

They have locking mechanism. You can just make out the locking tang on the last pic. The clip is on the other end.

Ah, there it is. Never mind then.

 

[snrkl]

For posterity, here is the plan I put together to figure out Static vent ports, rivets, avbay sled orientation etc...

 

[snrkl]

Avbay sled coming together:




Ended up using nylon risers and screws as the metal ones that I bought with the RRC3 were too tall.

 

[snrkl]

I used another left over IKEA dowel to raise the power and switch tie down so that there’s less bend in the cable.



Rocket naked (missing JLA3 and EFMini but with all recovery gear) weigh in.



Just over 2.7kg...

 

[snrkl]

It’s starting to be real! [emoji12]

 

[boatgeek]

Looks great! You did some really nice work on the AV sled.

Now the important question: what motor is its maiden flight?

 

[snrkl]

A CTI 411 I175-14A (W)...

I want my first DD to have the whole flight visible from the ground so I can watch the recovery unfold...

Once this is tested and if it all works (fingers crossed), plan is to fly it on a 38mm 6G J class motor and have a go at L2 certification.

 

[Andrew_ASC]

Go get that L-2!

 

[boatgeek]

Solid motor choices. One of the high school students I mentor just L1 certed on the I175. If you have a spacer, there's a bunch of cool J's in the 5G case. I'm a particular fan of the pink and green. I don't know why that has so much more than 6G, but there you go.

 

[snrkl]

Solid motor choices. One of the high school students I mentor just L1 certed on the I175. If you have a spacer, there's a bunch of cool J's in the 5G case. I'm a particular fan of the pink and green. I don't know why that has so much more than 6G, but there you go.

I bought the starter pack that came with a 3G and 6G case, and two spacers...

 

[snrkl]

So here is my attempt at making sure I get this rocket prepped properly and safely, while I have 4 kids running around (plus friends and their kids) at the next launch.

Comments welcome.. In particular, the bit I a spent most of my time thinking through is:

1. Safe loading of BP and eMatches
2. Order of operations so that I am not doing something in step X that prevents me from performing a step >X

I plan on doing a complete dry run (sans BP and motor) at home, to ensure the steps all work as planned.

Checklist:
Home Preparation:
Consumables:
- 6 2/56 nylon shear pins
- 4x 4mm Black Nylon plastic rivets
- 2x JTEC ematches
- 2x 1gram (TBC) 4F black powder
- O-ring grease
- NEW 9V Duracell battery
- Blue Zip ties x 20
- Black zip ties x 20
- Bluetak for eBay ematch lead hole sealing
- 3x M4 captive washer gnurled hex bolts
Tools:
- Monkey grip wrench
- multitool with shifter
- flat head screwdriver
- multiset modular scredriver set
- Step ladder
- iPhone
- RRC3 LCD
Propulsion:
- Motor case
- 4G
- 6G
- 2x Spacers
- Reload and igniter (picked up from AusRocketry on the day)
eBay:
- 4x M6 wingnuts
- 8x M6 Washers
- 8x M6 Nuts
Recovery:
- 3x Quicklink
- 2x 6m x 6mm Kevlar
- 18" drogue
- 48" main
- 2x 30cm x 30cm Nomex Blankets
- RRC3
- JLA3 ***charged***
- EFMini
- EFMini LIPO x 2 ***charged***
Field Preparation:
- Confirm RRC3 set for
- Drogue at apogee
- Main at 700ft (213m)
Fwd Payload:
- NC attached to recovery harness FWD
- Main Chute attached to recovery harness 30cm from NC
- Ensure spinner is installed
- Nomex attached to FWD Recovery Harness, 30cm aft of Main Chute
- NO ELASTIC BAND AROUND CHUTE
- Chute furled with shrouds wrapped
- Chute wrapped in nomex Burrito style
- Burrito AFT of main shock cord bundle
Motor preparation:
- Prepare motor per reload instructions
- DO NOT INSTALL EJECTION BP CHARGE (or follow steps to remove it)
- lightly grease the HAMR retainer threads

FinCan Payload:
- Recovery Harness quick link attached to FinCan eyebolt
- Drogue Chute attached to recovery harness 30cm from AVBay quick link
- Ensure spinner is installed
- Nomex attached to AFT Recovery Harness, 30cm aft of Drogue Chute
- NO ELASTIC BAND AROUND CHUTE
- Chute furled with shrouds wrapped
- Chute wrapped in nomex Burrito style
- Burrito AFT of main shock cord bundle
- Tape igniter for rocket motor to fin
EBay preparation:
- Ensure no igniters are wired to RRC3
- Ensure no black power is in FWD charge well
- Ensure no black power is in AFT charge well
- Ensure RRC3 switch on eBay switch band is OFF
- Ensure AGAIN RRC3 switch on eBay switch band is OFF
- connect RRC3 switch to RRC3
- connect 9v Battery to RRC3
- Ensure no tones or lights present on RRc3
FWD ematch wiring:
- LEAVING eMatch red cap in place, Unwind FWD eMatch, keeping leeds crossed and shorted
- Insert FWD eMatch through front ebay bulkhead hole
- Bend ematch wire head and place in EMPTY charge well, ensuring contact to the bottom of the well
- Passing the eMatch wire through the FWD end of the ebay tube, wire FWD ematch to MAIN terminals on RRC3
- zip tie FWD MAIN ematch to AVBay sled FWD position
AFT ematch wiring:
- LEAVING eMatch red cap in place, Unwind AFT eMatch, keeping leeds crossed and shorted
- Insert AFT eMatch through AFT ebay bulkhead hole
- Bend ematch wire head and place in EMPTY charge well, ensuring contact to the bottom of the well
- Wire AFT ematch to DROGUE terminals on RRC3
- zip tie AFT DROGUE ematch to AVBay sled AFT positions
Install sled and seal up ebay:
- Place sled inside ebay tube
- insert sled rails into sled and insert AFT ebay bulkhead
- insert fwd bulkhead
- add M6 washers
- secure and fasten with 2x M6 wingnuts
- Give ebay a shake test to ensure no loose components
- Check FWD igniter will still reach bottom of the charge wells
- Check AFT igniter will still reach bottom of the charge wells
Black Powder Loading:
FWD Charge:
- Install measured BP to FWD charge well
- insert eMatch as deep as possible into charge well
- pack TIGHT with dogbarf
- Tape charge well closed
- Secure eMatch wire to side of well with small black Zip Tie around charge well
- Seal FWD eBay bulkhead wire hole with bluetak.
AFT Charge:
- Install measured BP to AFT charge well
- insert eMatch as deep as possible into charge well
- pack TIGHT with dogbarf
- Tape charge well closed
- Secure eMatch wire to side of well with small black Zip Tie around charge well
- Seal AFT eBay bulkhead wire hole with bluetak.
*** EBAY is now loaded with BP charges ***
eBay AFT connection:
- connect AFT recovery harness quicklink to AFT ebay eye bolt
- Insert AFT end of eBay to Fincan, using key alignment
- install 3x 2/56 nylon shear pins
eBay FWD connection:
- connect FWD recovery harness quicklink to FWD ebay eye bolt
- Insert FWD end of eBay to fWD payload, using key alignment
- install 4x 4mm Nylon Push Rivets

Nose Cone GPS and Altimeter Power:
- Power on Eggfinder Mini Receiver and ensure no signal capture
- If no signal received, connect EggFinder Mini LIPO and ensure orange light
- Wait for signal fix from receiver, then install EFMini on NC sled
- Power on JLA3 and connect from iPhone
- install JLA3 on NC sled
- Insert sled into NC bay
- Install NC Bay bulkhead with 3x M4 gnurled captive washer bolts
- Ensure NC alignment with FWD payload tube
- NC Kevlar loop is OPPOSITE side of airframe to rail buttons
- Insert 3x 2/56 nylon shear pins on NC / FWD payload tube

Install motor:
- Install motor and secure HAMR retainer finger tight.

RSO:
- Have flight card ready
- Head to the RSO table...

On the pad:
- With rail pointing away from flight line, load rocket onto 1010 Rail
- Raise rail
- connect to JLA3 via Bluetooth
- !!! PRESS RECORD on JLA3 iPhone App !!!
- Ensure flight is recording
- Install igniter into motor per motor instructions and retain on nozzle per instructions
- check ignition leads by striking together, ensure no sparks
- connect ignition leads to each other and press connectivity check on remote pad launch box
- connect ignition leads to igniter leads
- press connectivity check on remote pad launch box
- ensure everyone is at a safe distance (3m +)
- using a screwdriver and stepladder, arm the rocket from the rotary switch on RHS of ebay
- ensure power on tone is heard, and RRC3 settles into 3beep pattern
- Mark Pad and location on flight card
- Return flight card to LCO and advise GO for launch

Fly, watch, enjoy, video, report...

 

[OverTheTop]

I have taken to sticking things to the rocket that I need at the launch. I used to stick the igniter to a fin to go to the pad, but now I stick bags with shear pins, motor retainer clips etc to the rocket at home so I won't forget to take them to the launch. Try it. You might like it .

 

[snrkl]

Colour coded the elements today to make field ID and hook up easier:



Also walked out my recovery system:

View attachment 360570

Sneak peek at ground testing today:




Write up and videos when I get a chance later tonight.

0.93g in each, charge wells worked brilliantly.

Learned an important and obvious lesson: no point testing aft separation with no motor installed! Problem rectified in test 2 with a vitamin tube that is perfectly sized as a 38mm motor replacement, and let me run an ematch through a hole I melted in the base of the container with a hot nail.

 

[snrkl]

Duplicate post

 

[snrkl]

Pic that keeps falling off the previous post...

 

[jqavins]

Checklist:
Home Preparation:
Consumables:
- 6 2/56 nylon shear pins
- 4x 4mm Black Nylon plastic rivets
- 2x JTEC ematches
- 2x 1gram (TBC) 4F black powder
- O-ring grease
- NEW 9V Duracell battery
- Blue Zip ties x 20
- Black zip ties x 20
- Bluetak for eBay ematch lead hole sealing
- 3x M4 captive washer gnurled hex bolts

For any little buggers that are easy to lose, pack spares. Given how (laudably) anal retentive you're being, I'd say make a spares list.

 

[snrkl]

For any little buggers that are easy to lose, pack spares. Given how (laudably) anal retentive you're being, I'd say make a spares list.

Lol - the equipment list is what I need. I will pack 2x for consumables that I have. [emoji12]

 

[RainerWolfcastle]

I would arm the altimeter before fitting igniter, in case of the worst and an electrical fault sends the rocket skyward unexpectedly at least the recovery system is functional.

Apart from that looks like you're well prepared! Nice size rocket to try the 5 and 6 grain motors out in.

 

[snrkl]

I would arm the altimeter before fitting igniter, in case of the worst and an electrical fault sends the rocket skyward unexpectedly at least the recovery system is functional.

Apart from that looks like you're well prepared! Nice size rocket to try the 5 and 6 grain motors out in.

Thanks. I’ll take that into consideration. I want to chat with the LCO on the day to find out what’s the norm at my club. I’m thinking they’ll probably agree with your assessment. [emoji12]

 

[snrkl]

Video of the ground test...

 

[boatgeek]

Looks great and extremely thorough!

It would be nice to leave the JLA3 attached to the NC sled if you can rather than having to connect it and then power it up. If you can't, no big deal. I second the idea of arming flight altimeters before inserting the igniter. I've seen a large rocket recovered by pickaxe due to a surprise launch. If it was my launch, I'd also leave the motor ejection charge in at full delay as a failsafe backup to the altimeter. The only other thing I can think of is whether you really need a ladder to reach up to the AV bay switch. Better to have it and not need it than vice versa though.

I like your approach of installing the ematch to the altimeter first and then loading BP late in the assembly process. I might steal that. I've been building glove tip charges and then twisting/taping them to a wire pigtail that goes to the altimeter, but that's another failure point.

 

[Steve Shannon]

I would arm the altimeter before fitting igniter, in case of the worst and an electrical fault sends the rocket skyward unexpectedly at least the recovery system is functional.

Apart from that looks like you're well prepared! Nice size rocket to try the 5 and 6 grain motors out in.

Thank you Rainer! Definitely! Always arm the recovery electronics before inserting or attaching the igniter. This is a safety consideration. 1. You don’t want to be arming electronics on a rocket that already has its igniter in place and
2. You want your recovery system to be ready so if something does happen and the motor lights the rocket recovers safely.