kevinkal
Insatiable Hobbyist
- Joined
- Feb 12, 2016
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I enjoy watching and listening to rockets that whistle loudly after burnout. Of the 4 HPR kits I've built, none whistle. Thus, I decided to add a split fin whistler to my rocket collection. Originally, I was looking for 4" airframes known to whistle such as the 4" BSD Thor and was disappointed to learn that they are no longer in production. In reviewing youtube videos, I could not find consistent whistle results for other split fin designs such as the Frenzy or Darkstar etc. However, I did find that a local club member had excellent whistle from his LOC Athena3, which looks just like a Thor but is just 3.1" diameter. I think the Thor looks good. While I prefer the easier accessibility of 4" diameter rockets, I decided that the 3" Athena3 had what I needed and picked one up from LOC precision.
Here's what came in the bag:
Originally, I thought I would simply keep it stock with motor eject at apogee, and install my Jolly Logic Chute Release. However, I've decided to convert to Dual Deploy with a single altimeter. I've witnessed too many rockets come straight back down at high speeds lately, and told myself that I'd always build in redundancy. This would give me a backup drogue deployment charge, with the Altimeter being the primary drogue charge, and the motor ejection being the backup.
Stock Tube Coupler and 1/4" open bend eyebolt:
I traced circles and cut pairs of altimeter bay bulkheads out of 0.06" G10 Fiberglass.
They're bonded together with Rocketpoxy. The pair of 3/16" through holes spaced 1.375" apart are for the 10-24 threaded rods.
I picked up some 316 stainless stamped Eye Straps to connect the shock cords. The manufacturer didn't give a load rating for these. I suppose their load capability is highly dependent on load direction. However, I did some manual pull tests and they are very strong axially and should be more than sufficient to handle any shock load this 50 oz. rocket might throw at them. The 10-24 threaded rods were cut to 6.875" long and the burrs carefully filed smooth. I debated using 8-32 threaded rod to save some weight, but went with 10-24
I found some very light 1/8" plywood in my stash, and used gorilla glue CA and microballons to build the altimeter sled. It has 2 sides with three 1/4" plywood spacers drilled to slide over the threaded rods. I manually simulated loads in excess of 100g's and the light plywood is more than strong enough.
A screw switch and StratologgerCF mounted with 3mm nylon stand offs and screws.
I simply drilled and tapped the thin and light plywood for 3mm-50 threads and was surprised/happy with the result. Strong and light. I had expected to feel the threaded wood fail when torqueing the fine threaded screws.. but that was not the case at all. Very solid. I scrubbed my plans to put a nylon nut on the backsides of each standoff thread.
I had some nice 350mAh 1S 65-130C LiPo packs with JST connector. They're thin and light at 15g. They should easily provide the 3A of current my 1.1 Ohm ematches draw.
I bonded some 1/4 plywood battery stops forward and aft, and plan to use a Velcro strap to hold the battery down and between the stops. 100 g's on this battery will produce a 3.3 lb load on the plywood stop.. which I tested to well over 10 lbs.
Today I'm planning to glue the altimeter bay tube into the payload tube. I'll then drill Three 1/8" vent hold through the bonded payload/altimeter bay tube, where one hole will lineup with the screw switch.
Here's what came in the bag:
Originally, I thought I would simply keep it stock with motor eject at apogee, and install my Jolly Logic Chute Release. However, I've decided to convert to Dual Deploy with a single altimeter. I've witnessed too many rockets come straight back down at high speeds lately, and told myself that I'd always build in redundancy. This would give me a backup drogue deployment charge, with the Altimeter being the primary drogue charge, and the motor ejection being the backup.
Stock Tube Coupler and 1/4" open bend eyebolt:
I traced circles and cut pairs of altimeter bay bulkheads out of 0.06" G10 Fiberglass.
They're bonded together with Rocketpoxy. The pair of 3/16" through holes spaced 1.375" apart are for the 10-24 threaded rods.
I picked up some 316 stainless stamped Eye Straps to connect the shock cords. The manufacturer didn't give a load rating for these. I suppose their load capability is highly dependent on load direction. However, I did some manual pull tests and they are very strong axially and should be more than sufficient to handle any shock load this 50 oz. rocket might throw at them. The 10-24 threaded rods were cut to 6.875" long and the burrs carefully filed smooth. I debated using 8-32 threaded rod to save some weight, but went with 10-24
I found some very light 1/8" plywood in my stash, and used gorilla glue CA and microballons to build the altimeter sled. It has 2 sides with three 1/4" plywood spacers drilled to slide over the threaded rods. I manually simulated loads in excess of 100g's and the light plywood is more than strong enough.
A screw switch and StratologgerCF mounted with 3mm nylon stand offs and screws.
I simply drilled and tapped the thin and light plywood for 3mm-50 threads and was surprised/happy with the result. Strong and light. I had expected to feel the threaded wood fail when torqueing the fine threaded screws.. but that was not the case at all. Very solid. I scrubbed my plans to put a nylon nut on the backsides of each standoff thread.
I had some nice 350mAh 1S 65-130C LiPo packs with JST connector. They're thin and light at 15g. They should easily provide the 3A of current my 1.1 Ohm ematches draw.
I bonded some 1/4 plywood battery stops forward and aft, and plan to use a Velcro strap to hold the battery down and between the stops. 100 g's on this battery will produce a 3.3 lb load on the plywood stop.. which I tested to well over 10 lbs.
Today I'm planning to glue the altimeter bay tube into the payload tube. I'll then drill Three 1/8" vent hold through the bonded payload/altimeter bay tube, where one hole will lineup with the screw switch.
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