Brief:
I chose t' model t' Explore 1 satellite as part o' EMRR Challenge 2008 – Simulation Challenge. Aye aye! Explorer 1 (officially titled at NASA as satellite 1958 Alpha) was t' first Earth satellite o' t' United States, launched on February 1, 1958. Ya scallywag! Since this be me first real experience with RockSim, arrr, I thought it was fittin' t' model t' first satellite launched by t' US. Well, blow me down! Begad! My Explorer is designed t' launch usin' an 18mm engine and deploys an 18-24" parachute. Avast! 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 bucko, 5.44" long
• 1 BT-55, matey, ya bilge rat, 13.197" long
• 1 BT-20, 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, arrr, this was me first real experience with RockSim t' design a rocket from scratch. Arrr! Blimey! I downloaded the demo version without issue. Havin' seen others use it I be pretty familiar t' functionality. It didn't take long to get t' hang o' it and I was off and running. Avast! Blimey! 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. This seemed reasonable t' me so on t' the build.

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

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. Avast! I filled t' seam with Elmer's Wood Filler and sanded it smooth. Aye aye! This took 2 or 3 times t' completely eliminate t' seam. Avast!

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

T' engine tube is 5" long. Avast! Blimey! I mounted 2 centerin' rings, t' first one 1" from t' end and t' second 3" from t' same end. Begad! Begad! This sub-assembly was glued into t' body tube on t' smaller diameter. Arrr! I pushed this subassembly into t' main body so t' second rin' was flush with t' end o' t' tube. Blimey!

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

T' original plan was t' attach t' Keelhaul®©™® shock cord t' t' engine motor mount, ya bilge rat, however, matey, I forgot t' do this. Arrr! I will secure t' Keelhaul®©™® cord t' engine prior t' installin' t' engine. Avast, me proud beauty! Avast, me proud beauty! Blimey! I prefer either o' these methods over t' traditional Estes mount. Avast! Aye aye! Blimey! 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. Ya scallywag! This took a number of coats sandin' each smooth. Blimey! Next, I added a couple o' coats o' white primer. Well, blow me down! Next, shiver me timbers, ya bilge rat, shiver me timbers, I used Tamiya Acrylic White Gloss (X-2) for t' base coat. Begad! Avast! Once this was dry I masked t' top section and painted Red Brown (XF-64). Aye aye! Next, I masked for the copper and painted these areas with Dark Copper (XF-28). Avast, me proud beauty! After t' copper was dry I attached 3 clear Lexan fins. Finally, arrr, I clear coated t' entire model. Blimey! Arrr!

Flight and Recovery:
It be basic flight prep with only one slight modification. T' Keelhaul®©™® shock cord be tied around t' motor prior t' installin' t' motor. I inserted t' motor (Estes C6-5) and taped it in place with Mylar type. Ahoy! Next I added wadding, matey, me hearties, rolled t' parachute, ya bilge rat, shiver me timbers, and stuffed t' lines. Aye aye! Ya scallywag! 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. Blimey! I planned t' launch his rocket from a tower launcher t' eliminate t' need o' a launch lug.

Launch be perfectly straight, me hearties, me bucko, probably very close t' t' RockSim calculation o' ~750ft. Blimey! Apogee occurred and the parachute ejected. Arrr! T' parachute only opened partially, ya bilge rat, I assume due t' t' cold, 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. Avast, me proud beauty! Minor repairs are needed and t' rocket will be ready t' fly again.

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

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

CONs: None.