Construction

Stock build for Level 1:

The Horizon is a great kit!  I built it according to the very thorough instructions with a couple of exceptions:

• I did not use the kit supplied eyebolt on the motor mount.  I replaced it with a 1/4" u-bolt from my local hardware store.
• I ordered an extra centering ring and epoxied it just forward of the fins on the motor tube.
• I did not epoxy the rear centering ring to the motor tube until after the tube had been installed in the booster, fins attached, and internal fillets applied to the fin/motor tube joints.
• I replaced the kit supplied nylon shock cord strap and tubular nylon shock cord with a 1/4" tubular  kevlar shock cord (with loops).

Modifications for dual deployment and Level 2:

I knew I wanted to eventually configure the Horizon for dual deployment.  To do this, I chose the LOC 4" avionics bay with extended payload section.  The LOC bay came with all the hardware needed to put the bay together.  I assembled the avionics bay according to the instructions.  However, I installed u-bolts on the end caps in place of the eyebolts.  One leg of the u-bolt went into the center hole of the end cap, and I drilled another hole for the second leg.  I could not find forged or welded eyebolts at my local hardware store, but they did carry u-bolts.  I didn't want to suffer a recovery failure from an opened eyebolt!

I decided to go with the PerfectFlite MAWD for my altimeter since it was able to record flight data in addition to having dual pyro channels.  I installed the MAWD mounting hardware on the plywood sled included with the LOC bay.  I also mounted a 9V battery holder from Commonwealth Displays to the sled. I used an altimeter wiring kit from Dog House Rocketry which included quick disconnect wiring along with terminal blocks.

I drilled holes for the terminal block screws and a pass through hole for the terminal block wiring in the end caps for the avionics bay.  I fastened the terminal blocks using the screws included in the wiring kit.  I passed the terminal block wiring through the drilled holes and attached to the terminal blocks.  I then sealed the holes with a dab of epoxy.  I drilled a hole through the switch band for a keyswitch from Aerocon Systems.  I soldered a wiring connector to the switch then installed it in the hole.  I drilled 3 static ports in the switch band based on size information from the MAWD manual.  Once everything was complete, I installed the altimeter and a battery.  I connected christmas tree bulbs to the terminal blocks and powered up the altimeter.  Once I verified continuity, I covered two of the holes and applied a vacuum to the third hole.  As soon as I let go, I could see the apogee bulb light up followed by the main bulb a couple of seconds later.  Success!

I attached the payload section to the avionics bay and drilled two 1/8" holes for the attachment points.  I removed the payload section and enlarged the holes in the avionics bay to allow a t-nut to be mounted from the inside.  I used a dab of epoxy to fasten the t-nuts to the avionics bay.  Once the epoxy was dry, I re-attached the payload section and installed the 4-40 screws.  Looking good!

Last up was the nose cone.  I drilled a hole in the nose cone shoulder and dropped in a 1/4" nut.  With some minor fiddling, I was able to get the nut threaded onto the end of an eyebolt inserted into the center hole of the nose cone.  I dripped some epoxy into the hole to secure the nut from coming loose.  Next, I placed the nose cone on top of the payload section and marked three equally spaced holes for 2-56 nylon shear pins.  I drilled the first hole, inserted a shear pin, then repeated this sequence for the remaining two screws.  I used a Sharpie to number the holes on both the nose cone shoulder and inside the payload section.