Starr Orbiter to 10,000ft

[jhill9693]

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.

 

[modeltrains]

It's the "Starr Orbiter" because it's more than a Star Orbiter, and I'm from Starr! (See what I did there?)

Unless otherwise informed I would have expected it to be named for the Lucky Starr character in some of Asimov's novels written under pseudonym Paul French..

 

[jhill9693]

All parts weigh in at 403 grams (0.89 pounds), including the altimeter and battery!

 

[cwbullet]

I simmed. asimilar flight on that and it should bust 10K.

 

[cwbullet]

Yup. I simmed it with a standard configuration and av bay, and that motor will go from 9500-10500. It will take a 12K waiver for most launches that have to stay below the 10% margin on the waiver.

 

[smstachwick]

Well that’s a must-see project for me. I hope you have a good videographer assigned for the flight.

 

[heada]

In order to hit 10kft, you'll have to be going M1.5+ How are you going to ensure the nosecone isn't a pile of melted styrene and the fins, which are pretty draggy, don't get ripped off?

 

[Neutronium95]

In order to hit 10kft, you'll have to be going M1.5+ How are you going to ensure the nosecone isn't a pile of melted styrene and the fins, which are pretty draggy, don't get ripped off?

A very low thrust long burn motor can get to high altitudes without going too fast. The H record was recently set on a H 13, and that flight probably barely went supersonic on it's way to 15,257 feet. The I59 is a pretty similar motor, although it has a decent kick off the pad. And I wouldn't even worry about taking a styrene nosecone past the sound barrier, if it was strong enough. Aerodynamic heating only really becomes a concern above Mach 2 or more.

 

[jhill9693]

A very low thrust long burn motor can get to high altitudes without going too fast. The H record was recently set on a H 13, and that flight probably barely went supersonic on it's way to 15,257 feet. The I59 is a pretty similar motor, although it has a decent kick off the pad. And I wouldn't even worry about taking a styrene nosecone past the sound barrier, if it was strong enough. Aerodynamic heating only really becomes a concern above Mach 2 or more.

Top speed for this design sims out at 600mph on the I59.

 

[jhill9693]

Yup. I simmed it with a standard configuration and av bay, and that motor will go from 9500-10500. It will take a 12K waiver for most launches that have to stay below the 10% margin on the waiver.

I’m building this with the GRITS launch next month in mind. Their waiver is 14,000ft. Hopefully the weather cooperates!

 

[jhill9693]

My build didn’t get very far before I realized nearly all of my bulkheads were too small. I’d tried cutting them with hole saws. Bah.

Yesterday I cut new ones with my circle cutter and a little “help” from Bob.

 

[jhill9693]

Today I did a test fit of everything to double check the airframe length and piston position. Everything looks good, and the piston bulkheads are just right.



For an altimeter sled, I used a 2.5” length of paint stirrer. Surprisingly, none of my hardware fit the holes in the Quark PCB. I had to go get M2 screws from the hardware store.



The assembled sled, screw switch, Quark, and 300mah 2S LiPo battery fit easily into a 3” BT-60 coupler.



The charge wells are nothing more than the sawed off nozzle ends of spent 18mm Estes black powder motors, with the insides reamed out with my Dremel. These will be epoxied to the bulkheads.

 

[cwbullet]

I’m building this with the GRITS launch next month in mind. Their waiver is 14,000ft. Hopefully the weather cooperates!

That is a good place to launch it. Be prepared to search.

 

[Brian H.]

I scratch-built an almost identical Star Orbiter rocket using blue tube and G10 fins. 38mm min MD, 23oz dry weight. It hit over 8500' on an I280DM and just shy of 10k with an Aerotech J270.

A GPS tracker in the nosecone is worth it's weight in gold!
I would have lost it without the tracker on every launch with motors as small as an H123 to over 4000'

I call it the Mach Orbiter because it hits over 750mph so easily with a lot of 38mm motors.

I280 launch:

 

[jhill9693]

I scratch-built an almost identical Star Orbiter rocket using blue tube and G10 fins. 38mm min MD, 23oz dry weight. It hit over 8500' on an I280DM and just shy of 10k with an Aerotech J270.

A GPS tracker in the nosecone is worth it's weight in gold!
I would have lost it without the tracker on every launch with motors as small as an H123 to over 4000'

I call it the Mach Orbiter because it hits over 750mph so easily with a lot of 38mm motors.

I280 launch:


View attachment 544256

Love it! Great photo

 

[jhill9693]

Assembled the inner piston. The upper and lower pistons are attached with 1/4” elastic shock cord knotted and glued through the stepped bulkheads.



I had to peel a layer off the 3” BT-60 couplers to get an easy slide through the outer piston.

This is the av bay, upside down. It fits into the bottom of the outer piston. Two small screw eyes (rated 45 lbs each) will attach to a Kevlar harness which will be anchored to the motor retainer screw eye. An access hole for the screw eye will double as a vent for the altimeter.



The upper av bay bulkhead is retained with a 1” strip of Teflon cut from a post office envelope. The strip was folded in half and glued with CA to the bulkhead. The fold was glued in like manner, and then the charge well on top.

 

[jhill9693]

Engine mount assembled. I’m using 1/16” basswood shims to center the 38mm engine mount tube inside the LT-175 airframe.



The rear engine mount tube has the shims spaced so as to provide 1/8” wide wells for the fins, which will go through the airframe wall.

 

[jhill9693]

First pass with Rust-oleum Sandable Filler Primer and 220 grit. Not bad, these were pretty rough after peeling off all the labels and packing tape.

 

[jhill9693]

Cut fin slots last night. Second pass today with more filler primer and 220 grit.

 

[mbeels]

Very cool, are you turning your own nose cone? I may have missed it, but will you have a radio beacon or GPS transmitter in there?

 

[jhill9693]

Very cool, are you turning your own nose cone? I may have missed it, but will you have a radio beacon or GPS transmitter in there?

Yes, gonna try to work up the gumption to do that tomorrow. It will be my first time. I have a drill press and a chisel

I’ve already prepared a small length of BT-50 and an end cap which will go inside the nose and house an Eggfinder Mini GPS tracker.

 

[tsmith1315]

Yes, gonna try to work up the gumption to do that tomorrow. It will be my first time. I have a drill press and a chisel

Cool. There's no doubt that you'll make it work.

My first (fiberglass) was with a hand drill turning it against a bench grinder wheel.

 

[jhill9693]

Here goes nothing!

 

[jhill9693]

Glued a 3/8” oak dowel to stick in the chuck. This will get sawed off and drilled out when finished, or at least that’s the plan. Plans change…

Printed out the nose profile from OpenRocket, then had to enlarge it 5% because it never prints out accurate scale for some reason.

Laid out the profile, kept a negative section from the template for comparison while turning.

 

[mbeels]

Good luck. I've never attempted turning a cone on a drill press, but I've seen people pull it off. So it is possible. Sometimes I've used a sanding block with coarse paper for shaping balsa on the lathe, it seems to work better in some situations.

 

[Handeman]

I did a foam nose cone that way, with a wood dowel as a centering point.

What I learned the hard way; Finish the whole nose cone before removing from the drill press. The chuck will put indents into the wood and if you remove it, you will NEVER get it back in the same place.

 

[tsmith1315]

I'm not a recycle freak, but I despise waste. It's super to see stuff re-used instead of tossed out.

This is a very cool build, and goes together so neatly. Very well made. Too bad the weather wasn't cooperative at GRITS.

Has you flown it yet?

 

[Hobie1dog]

very interesting build, keep the pics coming.

 

[Tumbler]

Very cool! Any updates?