Avionics Bay/Sled Build Thread?......Sure!

[BSNW]

Hello All-

I was beginning a new build of an electronics bay for a custom Mac-Performance kit I got with a little Christmas spending money. When I got about 20% into, it I had the idea of doing a build thread. I don't ever remember seeing build thread for an avionics bay. Often people (me initially) spend a ton of time on the rocket itself but show no love for the avionics bay. For me now, I actually love the avionics bay builds. IMO it is the heart of the rocket. I have even built bays for rockets that were not even built yet!

So, I thought I would do a short build thread on my current project. The purpose is to share ideas and hopefully pass on ideas to other folks. As it is, I learned many of my techniques and ideas from other people!

So here we go!

Andrew

 

[SecondRow]

Subscribed. I’ll probably be building my first electronics bay this year. And I’ve got lots of questions on wiring.

 

[BSNW]

I know that avionics bays are as personal as musical taste. There is no one best way to do things. My opinions on items like switches, battery holders are based on what has worked for me over time.

This sled/bay is for a 4" rocket. This size is also good and will work in a 5.5" rocket.

I like 2 sided sleds when I fly with two altimeters. I am also the type who like things spacious and spread out. I like things easy to get to and removable/serviceable. I use as little glue as possible. I like mechanical connections.

Also, I suggest making a mock-up of your altimeter. This way you can work on spacing and mounting without using your computer. See the photos below. I am now using the missile works RRC2+. Below is my mock-up.

 

[BSNW]

Please forgive me as I had already started this build before my idea to do a thread.

I basically took 1/8 ply and measured and cut the two sections of the sled. Since I fly two altimeters, this is double sided sled. I also save and use the heavy duty tubes that Aerotech puts their igniter in for guides that go over the all-thread. I carefully glued them on with wood glue. I also put fillets on the sides of the tubes. I will later saturate the tubes with thin/watery CA. In the photo below, I had already drilled my holes and set my 4/40 T-nuts (I will get into those later). Those are the two sides of the sled. The two sections of the sled are bolted together by 6 2/56 screws. See the holes on both ends and two in the middle.

 

[BSNW]

For switches, I have used the Missile Works screw switch with NO issues. When I had a voltage selector swich fail on the second use I have never used them since. These switches are incredibly robust and can be mounted and wired many different ways. I also like the 3D printed guide and screw holder. I use a second one to lift the switch off the sled as well. Notice I use 4/40 FLAT slot screws for the mounting as the switch screw itself is phillips head. I cant think of a better switch.

 

[BSNW]

For the batteries, I also like the plastic 9V battery holders. You can get them off the web or from Missile Works. I use 4/40 screws with the T-nuts to mount them on small nylon stand offs. I do this to give me space to run the two zip-ties around the battery. As you will see later, I will solder the wires to this holder.

 

[BSNW]

I use 4/40 and 2/56 screws for my sleds. I also use nylon stand offs for the altimeter and battery holders. You can get them at your hardware store too!!

 

[BSNW]

I put everything together to test fit. At this point I map out my wires. I then use 3/16 launch lungs to conduit the wires. ALSO....Note that I have also ran wires through a launch lug BETWEEN the sides of the sled. This is the cool thing about the double sided sled, you can hide the wires.

 

[BSNW]

It is time to run the wire!

 

[BSNW]

So LOTS more to do. After running the wire. The entire sled will get stripped down and taken apart. Then sanded, painted and reassembled and tested. Lots more to come.

Andrew

 

[BSNW]

Using some scrap wire, I do a mock of of how the wiring will be laid out. My only gripe with this new altimeter is that I wish the block for the drogue was on the outer end. As it is, I have to cross the main and drogue wires. I know I am OCD. This is the first time I am using the RRC2+. I have a fleet of RRC2 minis and they are getting old. I liked to old style two terminal connection for the power/battery on the older minis. I guess this is fine too. I just don't like change I guess.

I will glue on the conduits/launch lugs for the other side.Then is is on to sanding and finishing. I also have to work o the connections to the bulk-heads. Again, below is a photo of a how the wire will be laid out. NOTE: The real wires (color) for the battery-switch connection will be switched when I actually wire it all up. I know that the way it is shown currently (no pun intended!), the black and red should be switched. Again, this is just scrap wire to check the layout.

 

[Scott_650]

Andrew - no LiPo batteries? Can you digress from the build for a quick post on why you use conventional 9Vs instead of LiPos? Not in any way a criticism - I’m a total newbee when it comes to avionics bays and electronic deployment - so I’d like to hear your opinion on power sources...

 

[BSNW]

Andrew - no LiPo batteries? Can you digress from the build for a quick post on why you use conventional 9Vs instead of LiPos? Not in any way a criticism - I’m a total newbee when it comes to avionics bays and electronic deployment - so I’d like to hear your opinion on power sources...

Scott-

Thanks for your reply. This is a great question. I do not know that much about LiPo's. I know a couple people who are switching to them. I just know they need a charger and one has to remember to keep them charged properly. I guess I have been going with what I know. Duracell 9volt batteries can be purchased at a local store and the inner cells are spot welded for durability. I have done as many as 14 flights on one battery before I either tossed it or it showed signs of losing power. I kind of see them as an "easy sure thing". Weight is not an issue for me. I guess I would consider them if I was doing DD on much smaller projects. I think LiPo's are great, but I think they are the "new thing".

I also have observed and heard over time (at launches) others having issues with charging, or or ther issues I cant remember. I am totally not saying they are bad. I just have never had a single issue with a good 9V, thus never thought to change it. Besides, I like being able to go to the local hardware store and get a pack of batteries.

Would you be willing to tell me the advanrages and disadvantages of LiPo's? If they are truly a better option, I am all ears.

 

[gheem]

Hello All-

I was beginning a new build of an electronics bay for a custom Mac-Performance kit I got with a little Christmas spending money. When I got about 20% into, it I had the idea of doing a build thread. I don't ever remember seeing build thread for an avionics bay. Often people (me initially) spend a ton of time on the rocket itself but show no love for the avionics bay. For me now, I actually love the avionics bay builds. IMO it is the heart of the rocket. I have even built bays for rockets that were not even built yet!

So, I thought I would do a short build thread on my current project. The purpose is to share ideas and hopefully pass on ideas to other folks. As it is, I learned many of my techniques and ideas from other people!

So here we go!

Andrew

Great thread!! Thank you!!

 

[Terry Habegger]

Hello All-

I was beginning a new build of an electronics bay for a custom Mac-Performance kit I got with a little Christmas spending money. When I got about 20% into, it I had the idea of doing a build thread. I don't ever remember seeing build thread for an avionics bay. Often people (me initially) spend a ton of time on the rocket itself but show no love for the avionics bay. For me now, I actually love the avionics bay builds. IMO it is the heart of the rocket. I have even built bays for rockets that were not even built yet!

So, I thought I would do a short build thread on my current project. The purpose is to share ideas and hopefully pass on ideas to other folks. As it is, I learned many of my techniques and ideas from other people!

So here we go!

Andrew

Thank you
Very timely post.
I am building a front end duel deploy.
You have given me some ideas.
Again thank you.
Terry

Great thread!! Thank you!!

 

[BSNW]

I am glad you like the thread Terry.

Someone asked me a while ago how I line up everything since I do not use a switch band and all my switches are internal (on the sled). I thought I would show some photos of how I do this. I have been doing it this way for some time and it works every time. This is for lining up and drilling the vent holes and the holes for the screws that hold the coupler/bay to the payload sections.

1) The first thing I do is measure the half way point on the coupler. I then slide it in the payload to that mark and trace all the way around the coupler.

 

[BSNW]

Next I put the sled (with the switch on it), onto the all-thread and line up everything "expanded" a though it was "inside" the rocket.....I hope the photo below explains what I mean. This lets me measure (pretty closely) where the switch will be from the bottom of the payload/air-frame.

I then place a ruler from the middle of the switch straight over everything. I then place a mark on the payload. This tells me how far up from the bottom (of the payload) my vents will be.

 

[BSNW]

I now note that measurement.

 

[BSNW]

Now comes the fun part. I take a section of tape and cut it straight on either end. I then wrap it around the payload. Making sure to keep it level or straight all the way around. This is done by placing a tiny pencil mark at the measured point, in my case 8.3cm. I then mark the tape at the point it overlaps. This will give me my circumference.

 

[BSNW]

Pull the tape off and measure the total length. NOTE: I am making 4 vent holes and 4 mounting screws. See below.

 

[Scott_650]

I like the dual purpose vent/switch holes - good idea.

 

[BSNW]

Now take that same piece of tape and wrap it back on the payload....in my case, 8.3cm up from the bottom. This now shows me where to drill my vent holes.

 

[BSNW]

For the payload screw mounts..I measure the midpoint between each vent hole (~4.0cm) and make a mark. I then went 1.5cm down from the vent hole position and marked each.

 

[BSNW]

I then slide the coupler/av-bay into the payload and FIRMLY tape in place. I then drilled all my holes. Everything will line up nicely. Also remember the sled can be adjusted forward and backwards on the all-thread to make sure the screw switch lines up perfectly with the vent holes.

 

[BSNW]

To hold the payload in place, I use inverted 4/40 T-nuts that are epoxied into place on the inside of the coupler. Just make sure NOT to get any epoxy on the screw threads! Also in LOC bays you can use the t-nuts in the regular way as the stiffy couplers are much thicker.



This is how it looks on the outside of the coupler. I have the mounting screw in the coupler until the epoxy sets and so I wont lose them. The other holes of course, are the vent holes.

 

[cwbullet]

I don't think I have ever seen anyone do conduits like that. Neat idea.

 

[Brian Ditmer]

Using some scrap wire, I do a mock of of how the wiring will be laid out. My only gripe with this new altimeter is that I wish the block for the drogue was on the outer end. As it is, I have to cross the main and drogue wires. I know I am OCD. This is the first time I am using the RRC2+. I have a fleet of RRC2 minis and they are getting old. I liked to old style two terminal connection for the power/battery on the older minis. I guess this is fine too. I just don't like change I guess.

I will glue on the conduits/launch lugs for the other side.Then is is on to sanding and finishing. I also have to work o the connections to the bulk-heads. Again, below is a photo of a how the wire will be laid out. NOTE: The real wires (color) for the battery-switch connection will be switched when I actually wire it all up. I know that the way it is shown currently (no pun intended!), the black and red should be switched. Again, this is just scrap wire to check the layout.

View attachment 451535

got a question about that switch. Does that orange-ish film stay on it?

 

[BSNW]

got a question about that switch. Does that orange-ish film stay on it?

Don't really know if it "needs" to stay on. I have always taken mine off. Since the bottom of the switch has always been mounted on a stand-off, I guess it does not matter. The bottom of the switch in my earlier posts, fits nicely into the bottom of another switch stand-off. If you don't do that. I have used nylon standoffs to raise the switch to give it the clearance it needs.

I hope this helps!

 

[BSNW]

So I know it has been some time since I did anything with this thread.

I am picking up where I left off on Post #11. The sled is complete! I took everything apart and primed, sanded and painted everything. Then work got busy and I let it sit on my table. There was also launches to go to so my weekends were filled.

Anyway, today I put in an altimeter and used some bank lights to check everything. It is ready to fly! I like the new RRC2+ too. I also like the new 3D printed switch mounts. I used one side of another one to use as a pedestal to raise the switch up. It all is mounted with 4/40 T-nuts. Actually, everything is mounted with 4/40 T-nuts. Now all I have to do is finish painting the rocket!! Below are some photos of the completed sled. Remember, this is a double sided sled. The back side is a copy of the other side. I don't have zip ties on the battery as this was for testing only. You can also see that I loaded and tested each side one at a time....this is why one side does not have a battery and an altimeter. Anyway I hope you like it. OH!! the Avionics bay lids are painted with high temp grill paint. Makes clean-up easier. This should be it......Thanks, Andrew

 

[BSNW]

Some more shots just for fun.