2.56" E-bay

2.56" Blue Ebay

  • Part Number (PN): 10523
  • Qty per pack: 1
  • Weight: 358 g (12.53 oz)
  • Length/Thickness: 8" (20.32 cm)
  • Outer Diameter: 2.531" (6.43 cm)
  • Manufactured by: Always Ready Rocketry
  • Product Specs:
  • Fits 2.56" diameter Blue Tube and LOC tubes and kits.

Hurry! Only 2 Units in Stock

This kit for housing deployment and tracking electronics includes the tubes, 1/4" plywood bulkheads, a plywood mounting sled, nuts, washers, lock washers, eyelets, and threaded rods.

Typical Configuration of The Electronics In The Altimeter Bay

Dual deployment is the term applied to a rocket that ejects two separate recovery devices at different times during the descent of the rocket. The reason is to limit the wind-drift of the rocket, keeping the rocket close to the launch pad. The first (smallest) parachute is ejected by the altimeter at the apogee (peak altitude) point in the trajectory. This is the best time to deploy, because the rocket has no vertical velocity and the stresses on the parachute are smallest at this point. Because the rocket is coming down under a small parachute, it falls relatively fast, and doesn't drift very far if the wind is breezy. However, it is falling to fast to be safe...

That is where the second (LARGE) parachute comes into play. It is ejected out of the rocket when it is much closer to the ground. The altitude is determined by the flyer, but typically it is around 600 feet above ground level. Once the big parachute comes out, the rocket descends nice and slow, minimizing the damage to the rocket and objects on the ground. This two parachute system allows close-to-the-pad recovery, but keeps damage low (none).

The heart of the dual-deployment system is the special altimeter. It fires off the two ejection charges at the correct points in the flight. This dual deployment altimeter is mounted in the ebay of the rocket.

In dual-deploy configuration, you'll need to mount electronics yourself. Below are some pictures of a typical installation of a dual-deployment altimeter in a typical ebay. We recommend the Electronics Mounting Hardware set (not included with this ebay kit) for the installation.

Typical Ebay Configuration

End cap of EbayUnderside of ebay

Frequently Asked Questions

Q. Does this e-bay kit fit into the Aerotech and North Coast Rocketry 2.6" diameter kits?

A. Yes. It fits.

Features of the Avionic/Electroincs Payload Bays

Engine RetainerIn the past, building an electronics bay for your rocket was a chore. Finding all the various hardware, like the: nuts, screw eyes, threaded rods, and correct size metal tubes, meant several trips to various stores. Now you have everything you need in one location!

The convenience of having all the parts you need is a real treat. Instead of a project that could last days, you'll have your avionics bay built in less than a half hour.

Better yet, is if you get one that is made from the super-strong Blue Tube, so it is practically indestructible!

Basically, the payload bay kit is a long tube coupler that is capped off on each end by an extra thick, 1/4" thick plywood bulkhead. Usually one (but sometimes both ends) is removable. To keep it together, two threaded steel rods are passed through both bulkheads and cinched down on each end by a couple of washers and nuts.

The electronic payload is mounted on a plywood base, which is called the "sled." This bed is either epoxied to two brass tubes, or glued to a laser cut brace with holes, which just so happen to fit nicely over the threaded steel rods. Nuts are wound down the threaded rods to hold the sled in place. The sled, and hence the electronic payload, when inserted inside the coupler, is held securely in all directions.

Electronics Bay in FlightAlso on each bulkhead is a large screw eye. You'll attach your shock cords and parachutes to these eyelets. Since everything is attached and tightly cinched down, you can be assured that your rocket will stay together throughout the entire flight!

The only extra work you have to do is to drill your holes in the bulkheads to attach the ejection charge holder and to allow the wires to pass through the bulkhead to the electronic payload. It is a really nice set-up that you'll love because of its simplicity.

The biggest difference between the Madcow brand and the Blue Tube payload bays, besides the actual coupler material, is that the Blue Tube payload bays come with a center spacing ring. With that ring, you can drill holes into the payload bay for air and for a switch access. With the Madcow e-bay, you will need to drill through your rocket's bodytube, then make sure things stay aligned with removable rivets.

Electronics Bay Location
Single vs. Dual Deployment
How Does Dual Deployment Work?

Dual Deployment, in general terms, means that two parachutes are ejected out of the rocket. The first one is small, and is ejected at apogee. The other is large, and is ejected when the rocket is closer to the ground. The advantage is that the rocket falls fast for most of the descent and doesn't drift very far. It is also called "close-to-the-pad" or "close-proximity" recovery.

The key to the system is the electronic brains of the rocket. This electronic payload works by sensing the altitude of the rocket and then sending electricity to two different ejection charges at the appropriate times.

As the rocket takes off, this electronic payload is calculating the altitude of the rocket. When it senses the peak altitude, called apogee, the electronic brain sends electricity to one of the igniters. This igniter sets off a small charge of black powder. That pressurizes one section of the rocket (usually the back end) and spits out the small parachute (called a drogue chute).

While the drogue chute brings down the rocket quickly, the electronic payload is still sensing the altitude of the rocket. When it descends to a pre-programmed height (which you control), it then triggers a second time. This time is ignites another black powder ejection charge which pushes out the main parachute (usually stored in the front part of the rocket). Since the rocket is now closer to the ground, the wind really doesn't have the time to push it downrange too far. So it lands slowly, but much closer to the launch pad. That means you don't have to walk very far to retrieve your rocket.

Tools needed to assemble this kit:
  • Liquid epoxy (5-minute epoxy works fine)
  • Fix-It Epoxy Clay to attach the plywood bed to the brass rails.
  • Drill and drill bit to make holes to attach the ejection charge canisters
Frequently Asked Questions about the Payload Bays

Mount Electronics DVDQ. How do I secure the electronics into my new electronics payload bay?

A. We've created a special DVD that will walk you through the steps required to securely mount your electronics. It will help you gain the confidence to tackle complex rocket projects. Your friends, who thought you were all-thumbs, will be amazed at what you've accomplished on your own. DVD: How To Mount Electronics In An E-bay

Q. Does it matter which parachute is in the front?

A. Not really. But if you put the drogue chute (the smaller one) in the rear of the rocket, you can also use the built-in delay charge of the rocket motor (if your rocket motor has one) to provide extra redundancy. So if the electronics should fail, you would still have a back-up ejection charge from the motor to kick out the drogue chute. Or, visa-versa...

Q. Is there enough room inside the ARR 38mm diameter bay for electronics and batteries with two threaded rods, brass tubes, sled, and misc hardware? That seems like it might be a very tight fit.

A. See the image below. The bay will be tight. But you're a person with above average intelligence, or you wouldn't be reading this FAQ. I'm sure you'll see that a 9V battery (if your electronics requires one) will have to be housed on its side so that it is between the rails. The sled itself is made from aluminum, which is thinner than the 1/4 inch plywood in the larger electronic bays. That helps give you some additional room. Finally, the threaded rods are skinnier, which also gives you a bit more room to play with. The key is that all the basic parts are included in the bay, which is the whole point; to save you time. All you have to do is make your necessary modifications to make everything fit.

38mm Electronics Bay
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Comparison - Electronic Bays
Product P/N I.D. O.D. Length Weight Material Fits Part Price Buy Now!
18mm Altimeter Bay for Foam Nose Cones 10540 -- -- -- -- -- --
Avion Payload Bay Add-On 10200 -- -- -- -- -- --
29mm Ebay Kit 10542 -- -- -- -- -- --
BT-55 Ebay Kit 10543 -- -- -- -- -- --
38mm Blue Ebay 10521 -- 1.504"
-- #10501
BT-60 Ebay Kit 10544 -- -- -- -- -- --
1.9" Ebay Kit for Aerotech Rockets 10545 -- -- -- -- -- --
54mm Blue Ebay 10522 -- 2.133"
-- #10502
2.56" Blue Ebay 10523 -- 2.531"
-- #10503
2.6" Madcow Ebay 10533 -- 2.6"
-- -- -- #11013
75mm Blue Ebay 10524 -- 2.99"
-- #10504
4.0" Madcow Ebay (98mm) 10535 -- 3.9"
-- #11021
98mm Blue Ebay (4.0") 10525 -- 3.9"
-- #10505
5.5" Blue Ebay 10526 -- 5.36"
-- #10506
6.0" Blue Ebay 10527 -- 5.973"
-- #10507
56mm x 10" Clear Tube (BT-70 size Payload Tube) 10165 2.18"
Clear Plastic --
Reviews for the 2.56" Blue Ebay

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