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So... I built my Estes Star Orbiter with the Vander-Burn plywood upgrade, which left a set of balsa fins laying around. I saw someone post on Facebook photos of how theirs got re-kitted on an I200. Not mine, thankfully, and won't ever be mine, probably... maybe.
Anyway, around about that time, I saw that E-Rockets was (is) having a closeout sale on their old heavy wall LT-175 tubes, which are just a hair larger than a 38mm motor mount.
And then I noticed that the yellow tubes that my Aerotech J520 and J350 reloads came in (I just got my L2) are EXACTLY the same dimensions as the LT-175!
So working with what I have, and a few incidentals that I promptly ordered, I came up with this guy, which should hit 10,000ft on an Aerotech I59-P (RMS 38/480 reload):
It's the "Starr Orbiter" because it's more than a Star Orbiter, and I'm from Starr! (See what I did there?)
This is an unusual design that is meant to be lightweight, aerodynamic, cheap to build, and explore several build techniques and material choices that will be new to me.
In case it isn't readily apparent in the above side view, this design uses a forward minimum-diameter retainer, which is a 5/16-18 stainless eye bolt through a 1/4" thick bulkhead.
The design is meant to add to boost the ordinary structural strength of the heavy wall cardboard tubes with an internal structural design: the aft end is held together by the aluminum motor casing, with the thrust pushing against the bulkhead. This in turn will be in direct contact with the piston bulkhead, which will in turn be in contact with the nose cone via two 1/8" dowels.
About that piston: there's another piston inside. It's dual-piston, Russian doll style. An Eggtimer Quark will reside in the aft end of the outer piston, with ejection charges on each side of the bulkheads. The outer BT-60 piston pushes out the drogue parachute, the inner piston pushes out the main parachute. I'll be using Top Flite thin mill X-type parachutes for both (10" and 24"). ASP has the best deal on these that I could find.
Balsa fins (not plywood) will be papered with card stock and finishing epoxy, which I have tested before on one other occasion and was quite impressed with the end result. The epoxy actually soaks into both the paper and the balsa, very little sanding is required for an ultra-smooth end result, and they are so stiff that they clink. All at a fraction of the weight of fiberglass or even plastic.
Stay tuned... I'm starting the build NOW.
Anyway, around about that time, I saw that E-Rockets was (is) having a closeout sale on their old heavy wall LT-175 tubes, which are just a hair larger than a 38mm motor mount.
And then I noticed that the yellow tubes that my Aerotech J520 and J350 reloads came in (I just got my L2) are EXACTLY the same dimensions as the LT-175!
So working with what I have, and a few incidentals that I promptly ordered, I came up with this guy, which should hit 10,000ft on an Aerotech I59-P (RMS 38/480 reload):
It's the "Starr Orbiter" because it's more than a Star Orbiter, and I'm from Starr! (See what I did there?)
This is an unusual design that is meant to be lightweight, aerodynamic, cheap to build, and explore several build techniques and material choices that will be new to me.
In case it isn't readily apparent in the above side view, this design uses a forward minimum-diameter retainer, which is a 5/16-18 stainless eye bolt through a 1/4" thick bulkhead.
The design is meant to add to boost the ordinary structural strength of the heavy wall cardboard tubes with an internal structural design: the aft end is held together by the aluminum motor casing, with the thrust pushing against the bulkhead. This in turn will be in direct contact with the piston bulkhead, which will in turn be in contact with the nose cone via two 1/8" dowels.
About that piston: there's another piston inside. It's dual-piston, Russian doll style. An Eggtimer Quark will reside in the aft end of the outer piston, with ejection charges on each side of the bulkheads. The outer BT-60 piston pushes out the drogue parachute, the inner piston pushes out the main parachute. I'll be using Top Flite thin mill X-type parachutes for both (10" and 24"). ASP has the best deal on these that I could find.
Balsa fins (not plywood) will be papered with card stock and finishing epoxy, which I have tested before on one other occasion and was quite impressed with the end result. The epoxy actually soaks into both the paper and the balsa, very little sanding is required for an ultra-smooth end result, and they are so stiff that they clink. All at a fraction of the weight of fiberglass or even plastic.
Stay tuned... I'm starting the build NOW.