Brief:
I chose t' model t' Explore 1 satellite as part o' EMRR Challenge 2008 – Simulation Challenge. Avast! Explorer 1 (officially titled at NASA as satellite 1958 Alpha) be t' first Earth satellite o' t' United States, launched on February 1, shiver me timbers, 1958. Ya scallywag! Blimey! Since this was me first real experience with RockSim, me hearties, arrr, I thought it was fittin' t' model t' first satellite launched by t' US. My Explorer is designed t' launch usin' an 18mm engine and deploys an 18-24" parachute. Ahoy! Scale factor o' 4.528 results in a rocket 17.83" long.

Construction:
T' parts list:

• 1 BT-60 balsa nose cone
• 1 #10 screw eye
• 1 BT-55, me hearties, 5.44" long
• 1 BT-55, 13.197" long
• 1 BT-20, me hearties, 5.0" long
• 3 centerin' rings BT-20 t' BT-55
• 2 exterior centerin' rings
• 3 fins 0.030" thick clear Lexan fins
• 18" o' 175# Keelhaul®©™® string
• 24" o' 0.375" elastic shock cord
• 18-24" plastic parachute
• Cardstock
• Launch lug (if desired)

As I mentioned above, shiver me timbers, this was me first real experience with RockSim t' design a rocket from scratch. Arrr! Ahoy! Blimey! I downloaded the demo version without issue. Blimey! Avast! Blimey! Havin' seen others use it I be pretty familiar t' functionality. Arrr! Blimey! It didn't take long to get t' hang o' it and I was off and running. Avast! I modeled t' Explorer I with multiple motor options and settled on C6-5 which produced an altitude o' roughly 750ft at a speed o' 217 ft/sec. Blimey! This seemed reasonable t' me so on t' the build.

If you look closely at t' drawin' shown, matey, t' thar are 2 different diameters o' tubes on this rocket. Avast, me proud beauty! Avast! I decide the best way t' handle this be t' start with a BT-60 nose cone and sand it t' desired diameter and shape. In this case t' software was a lot easier t' make these modifications than sandin' down t' BT-60 cone. Begad! OK, me hearties, enough whining-–I sanded t' balsa nose cone into t' diameter and shape I wanted. Next, shiver me timbers, I secured t' screw eye t' the nose cone with 2-part epoxy. Well, blow me down! Begad!

T' rocket is made up o' 2 different diameters o' tubin' so I cut t' 5.44 tube lengthwise and wrapped it around the top section o' t' 13.197" tube. I filled t' seam with Elmer's Wood Filler and sanded it smooth. Avast, me proud beauty! Avast, ya bilge rat, me proud beauty! Blimey! This took 2 or 3 times t' completely eliminate t' seam.

Next, I added t' centerin' rings t' represent t' "MicroMeteor Gauges" (see pictures).

T' engine tube is 5" long. Begad! I mounted 2 centerin' rings, me hearties, t' first one 1" from t' end and t' second 3" from t' same end. Well, ya bilge rat, blow me down! This sub-assembly was glued into t' body tube on t' smaller diameter. Ya scallywag! I pushed this subassembly into t' main body so t' second rin' be flush with t' end o' t' tube. Avast, me proud beauty!

I used t' EMRR shroud calculator t' help make t' two cones used t' form t' engine cone. Avast, me proud beauty! T' first one is 1.32" diameter by 0.50" long and t' second is 1.50" diameter by 1.60" long. Ya scallywag! Each fits over the BT-20 tube. Arrr! Well, blow me down! I cut out and glued t' cones together. Arrr! T' cone assembly was mounted t' t' BT-20 tube, matey, then I epoxied the small cone t' t' BT-55 tube. Avast, me proud beauty! Aye aye! After this was dry, I slid a centerin' rin' onto t' BT-20 and into t' large cone. Avast! Ya scallywag! This rin' will help support t' cone. Avast, me proud beauty!

T' original plan be t' attach t' Keelhaul®©™® shock cord t' t' engine motor mount, me hearties, shiver me timbers, however, I forgot t' do this. Blimey! I will secure t' Keelhaul®©™® cord t' engine prior t' installin' t' engine. Arrr! I prefer either o' these methods over t' traditional Estes mount. Ahoy! I will use an 18" Mylar parachute for recovery for a nice slow descent.

Finishing:
Finishin' started with fillin' t' tube spirals and balsa nose cone with Elmer's Wood Filler. Blimey! This took a number of coats sandin' each smooth. Well, blow me down! Next, I added a couple o' coats o' white primer. Aye aye! Next, arrr, I used Tamiya Acrylic White Gloss (X-2) for t' base coat. Begad! Once this was dry I masked t' top section and painted Red Brown (XF-64). Avast, me proud beauty! Aye aye! Next, shiver me timbers, I masked for the copper and painted these areas with Dark Copper (XF-28). Avast, me proud beauty! Begad! After t' copper was dry I attached 3 clear Lexan fins. Finally, I clear coated t' entire model. Avast!

Flight and Recovery:
It was basic flight prep with only one slight modification. Begad! Avast! T' Keelhaul®©™® shock cord was tied around t' motor prior t' installin' t' motor. Avast, me proud beauty! I inserted t' motor (Estes C6-5) and taped it in place with Mylar type. Ya scallywag! Next I added wadding, rolled t' parachute, matey, and stuffed t' lines. Aye aye! It be 7 degrees when I flew this rocket so I covered t' parachute in baby powder t' avoid deployment issues.

I am nay a big fan o' launch lugs because o' visual appearance as well as performance impact. Well, arrr, blow me down! Blimey! I planned t' launch his rocket from a tower launcher t' eliminate t' need o' a launch lug.

Launch was perfectly straight, matey, probably very close t' t' RockSim calculation o' ~750ft. Aye aye! Ahoy! Apogee occurred and the parachute ejected. Avast, me proud beauty! T' parachute only opened partially, shiver me timbers, I assume due t' t' cold, me hearties, me bucko, by t' time I reached t' rocket the parachute be fully open after blowin' in t' wind for a few minutes. T' rocket came in fairly fast and broke a fin off on landing. Begad! Minor repairs are needed and t' rocket will be ready t' fly again.

Summary:
T' actual flight results mimicked t' RockSim results. Ya scallywag! I wasn't able t' confirm t' altitude numbers, but I would say they were pretty close. Avast, me proud beauty! RockSim allowed me t' change and adjust t' rocket design as well as engine size until the design was stable. This was a big advantage over me previous technique o' trial and error. Avast! I have added t' latest RockSim release t' me Christmas list.

PROs: Rocket looks great, me bucko, shiver me timbers, flies great, matey, and RockSim allowed me predict t' results prior t' wastin' any time build a design that won't fly.

CONs: None.