Wildman JR Avionics Bay Question

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atlcdp

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Has any built an electronics sled for a Wildman Jr? I bought one for my TRA L1 launch, but want to include electonics.
 
Yea, I built one. Great rocket. I just built the ebay using the bulkheads provided and a 1/4-20 threaded rod. I use nuts then eyenuts on the ends jammed together so they don't untwist. The sled is just a loose piece of 1/8" plywood large enough so that when the ebay is all screwed together, it doesn't move much. The altimeter is on one side on tall standoffs so the threaded rod clears under it. The other side I just tape the 9V battery on, with the cap down and resting on the aft bulkhead (open end in the picture is aft). I'm sure there are more elegant ways to do it, but it works for me.

wildmanjr_ebay.jpg
 
Mines is very close.
1/4 rod thru the center , sleds the same and no terminals on the end ( less connections, better chances) Pyro's straight to the ALT. and I just love using U=bolts instead of Eyelets. I've choose (3) vent holes for my AV bay, worked every time so far with about 10 launches and this WM JR loves WARP-9 motors.
 
Here's a question that's always been bugging me. For altimeter bays with one rod through the center, how do you keep the sled from spinning around?
 
I make the sled fit close to tight from end to end and add a bit of foam to snug it down.
And if you use U=bolts the internal nuts will stop any spinning of the sled too!
 
I make the sled fit close to tight from end to end and add a bit of foam to snug it down.
And if you use U=bolts the internal nuts will stop any spinning of the sled too!

Thanks! I knew it was something simple.:rolleyes:
 
Mines is very close.
1/4 rod thru the center , sleds the same and no terminals on the end ( less connections, better chances) Pyro's straight to the ALT. and I just love using U=bolts instead of Eyelets. I've choose (3) vent holes for my AV bay, worked every time so far with about 10 launches and this WM JR loves WARP-9 motors.

The U-Bolts are nice; I prefer them as well. When I built mine, I couldn't find small enough ones at my local ACE, and wanted to fly in a couple of days so I used jam nuts and swivels. While the eyenuts have worked for a half-dozen flights, I may still upgrade mine to use u-bolts.
 
The Wildman Jr. was also my L1 rocket, and the first altimeter bay I have built. I think it came out pretty well, and it has worked perfectly on every flight so far. The small diameter makes for some pretty tight packaging constraints.

I built it around a Perfectflite Hi-Alt45K altimeter, with dual redundant 9V alkaline batteries for power. There are 2 toggle switches accessible through 5/16" holes in the switch band. One switch applies power to the altimeter, and the other isolates the pyro charges from the altimeter outputs for safety. The switch access holes also act as the pressure equalization holes for the barometric sensor.

The electronics "sled" is made from single-sided copper clad G10 fiberglass stock, normally used for fabricating PC boards. 2 lengths of thinwall brass tubing are soldered along the edges of the sled to slide over the tie rods which hold the entire assembly together. The tie rods are 1/4"-20 stainless allthread rod. Each end cap has a small aluminum block attached to transfer the axial load to the tie rods, and recovery harnesses are attached via 1/4" forged eyebolts attached with nylock nuts.

The batteries are retained in plastic snap-in holders made by Keystone Electronics. The altimeter itself is mounted on 4-40 threaded standoffs, and the switches are mounted directly through the sled base itself. All wiring is done with 22 AWG stranded hookup wire, twisted into pairs to reject electrical interference.

Ejection charge connections are made through the bulkheads with miniature binding posts. I really would have liked to incorporate ejection charge holders into the bulkheads, but there wasn't enough room with a diameter this small. I opted for separate ejection charges in "single use" plastic canisters. Typical ejection charges are ~2 grams of Pyrodex "P" or Triple Seven, set off with a Quest Q2G2 igniter. The electronics sled is connected to the binding posts via 2-pin Molex connectors, to allow the sled to be moved between rockets without needing to disconnect individual wires from the screw terminals.

External.jpg

Switch band.jpg

Exploded.jpg
 
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As stated above; cut out you mounting plate as close to the ID of the coupler as possible then I wrap some duct tape to get a tighter fit. It's really not necessary with baro units more so with accelerometer based units.



JD


Here's a question that's always been bugging me. For altimeter bays with one rod through the center, how do you keep the sled from spinning around?
 
I used a threaded rod, off center, so the sled touched the sides of tube. There was just enough room to use some standoffs for my altimieter and 9v battery holder.

I got my L1 on a Wildman Drago, single deploy. Then my L2 on the Wildman Jr dual deploy. The altimeter and EBAY worked great.
 
Bob,

That sure is a good looking AV bay.
I just purchased a Wildman Jr. Although its first flights will be single deploy (looking to get L1 certified this Summer), this will likely be my first foray into dual deploy. I would be interested in your sled schematic if you wouldn't mind sending it.

Tom
NAR 87916
 
Thanks all for your input. My e-bay ended up looking very much like the others on the thread. I used my completed Wildman Jr to get my TRA level II. Everything worked just like it was supposed too.

Thanks for all the great info!
 
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