Madcow 4" fiberglass Super DX3 build thread

I started the build on the e-bay, since I have not seen a lot of photos and how to's on the e-bay, I will be posting pics and how to on the e-bay

I inserte the e-bay in the aft end on the body tube to mark lines using the fin slots.

Here I put the e-bay in th upper portion of the body tube and transfer the lines on the tube, these lines will be use for shear pins for the nose cone and bolts to hold the e-bay to the body tube.

the T nuts are epoxied inside the e-bay for the bolts to screw into. after transfering the lines onto the upper body tube i measured 1 inch from the bottom of the upper body tube and drilled a 1/8" hole through tub and e-bay, then I removed the e-bay and drilled through the 1/8" hole with a 9/64" bit for the T nut. After the epoxy is dried,I put the e-bay back in the body tube and tighten the bolt and drilled the next hole, by doing this you will have a better chance for all the holes to line up. IMPORTANT: you must drill one hole a time or the holes will NOT line up

Its good practice to mark the first hole that you drilled on the body tube and e-bay so you can put things together faster.

one all thread is longer so it will be easy to get the bulk head on the e-bay. I will change out the eye bolts for some forged eye bolts

subscribed!

I went with U bolts, I found these at home depot for $0.95 a pice

this is the biggest motor that I'mm going to us in the DX3, it's a 54/1706, as you can see it's longer then the motor mount tube,the problem is the quick link is too big and touching the moto case, with out spending more money for a longer motor mount tube or a aft end with a taped end for a forged eye bolt, would it be better to tie the cord on the u bolt or put the u bolt thru the lupe hole?

I'd make a loop higher up in the shock cord (maybe 24in past the one you have now). Then, Run the Kevlar through your U bolt and attach both loops together with a quicklink. That way, the quicklink is well away from the motor casing and the cord is easily removable.
I'm liking the build so far!

Alex

I think Alex has a good solution. Effectively extend the u-bolt using a length of kevlar. I used the same concept on my THOR build when I discovered that the quicklink would not fit between an eyebolt and the body tube.

I like the avbay build, I may have to steal the technique (for personal consumption only, I have a prescription, but I don't inhale)

Forget the u-bolt just attach shock to a threaded forward closure.
gp

here I use tape to hold the nose cone on the airframe, then I drilled all three holes for the 4-40 shear pins, the second photo shows the inside the nose cone, i glued in 4-40 T nuts so the shear pins can screw in to.

here I made the bulkhead removable so I can add weight if i need to and to remove the rest of the shear pins after a launch.

Subscribed!

So far for this build, I've been utilizing a lot of new techniques, and learning lots of new information that will come in handy latter when I decide its time to go for my L3 project, until then I'm just having fun.

before I start drilling holes in the bulkhead, I position the blastcaps and wire terminals to make sure they wont be in the way of any thing, then I marked them then I drilled the holes, thenext two photos show every thing bolted on.

here are the electronics that will be going in the DX3, I'll wire it up next weekend

I bought a 2' by 4' sheet of hardwood 1/4" thick, at $10 a sheet this is pricey, but it looks nice, I'll be making the e-bay sled for the DX3, and if I make any mistakes I'll have plenty of wood to make more sleds, I'll post pics when wiring up the e-bay.

I like it!!

Spooks said:

I like it!!

Click to expand...

thanks Spooks

Spooks said:

I like it!!

Click to expand...

thanks Spoks

here I'm testing the wire hookup before i put on a layer of epoxy, this way if there is a problem with the wire hook up, this is the best time to fix the problem.

here is the front and back of the amost done e-bay

the e-bay is complete, here I'm testing the wire hookups and the altimiters to make sure everything is working properly. Now that the e-bay is done its time to build the rest of the Super DX3. I hope this e-bay build thread gave you some ideas on how to do your own or you can use my method, there is no wrong way to do an e-bay. This is what I learned over the years and wanted to share. I will continue to post pics as I bild the DX3, so stay tuned.

I really appreciate the time your taking to document this!

I have my ebay on my workbench where it has sat for a month now just staring at it, occasionally working on it, wondering how can I make this work right!!

Been told by an L3 flyer from this forum I am just over thinking it, so after this and several others and his advice, I think I may have figured it out finally!

Spooks said:

I really appreciate the time your taking to document this!

I have my ebay on my workbench where it has sat for a month now just staring at it, occasionally working on it, wondering how can I make this work right!!

Been told by an L3 flyer from this forum I am just over thinking it, so after this and several others and his advice, I think I may have figured it out finally!

Click to expand...

Not a problem, I've seen some post on e-bays but not in depth from start to finish, this is one of the reasons why I posted my build from start to finish. I glad this build thread gave you some ideas on how to proceed with your e-bay.

almost forgot the static holes for the altimiters, here I put a sheet of paper around the body tube so all the holes are inline with each other and that a hole is at the same point as the two switchs for the altimiters, its important to measure measure measure before you drill

to get the holes to line up perfectly every time, put the e-bay in the body tube and screw in all the shear pins to prevent the e-bay from moving.
dia. times dia. times length times 3.14 gives me 382.0752 cubic inches of air for the e-bay and 1/4" hole per 100 cubic inch. so I need 4 holes at 1/4"
since I'm drilling fiberglass and not want to just drill 1/4 inch hole I started with a smaller drill bit and worked my way up to the 1/4" drill bit