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, ya bilge rat, launched on February 1, me bucko, 1958. Since this be me first real experience with RockSim, I thought it was fittin' t' model t' first satellite launched by t' US. Well, blow me down! My Explorer is designed t' launch usin' an 18mm engine and deploys an 18-24" parachute. 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, 5.44" long
• 1 BT-55, 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, me hearties, shiver me timbers, this be me first real experience with RockSim t' design a rocket from scratch. Arrr! Blimey! Ahoy! Blimey! I downloaded the demo version without issue. Havin' seen others use it I was pretty familiar t' functionality. Arrr! Blimey! It didn't take long to get t' hang o' it and I was off and running. 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. Well, blow me down! Blimey! Avast, me proud beauty! Blimey! This seemed reasonable t' me so on t' the build.

If you look closely at t' drawin' shown, me hearties, t' thar are 2 different diameters o' tubes on this rocket. 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. Aye aye! In this case t' software was a lot easier t' make these modifications than sandin' down t' BT-60 cone. Aye aye! OK, enough whining-–I sanded t' balsa nose cone into t' diameter and shape I wanted. Arrr! Ya scallywag! Next, I secured t' screw eye t' the nose cone with 2-part epoxy. 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. Avast! I filled t' seam with Elmer's Wood Filler and sanded it smooth. Avast, me proud beauty! 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. I mounted 2 centerin' rings, t' first one 1" from t' end and t' second 3" from t' same end. Arrr! Blimey! This sub-assembly was glued into t' body tube on t' smaller diameter. I pushed this subassembly into t' main body so t' second rin' was flush with t' end o' t' tube. Aye aye! Aye aye! Blimey!

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

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

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

Launch was perfectly straight, probably very close t' t' RockSim calculation o' ~750ft. Ya scallywag! Blimey! Apogee occurred and the parachute ejected. Begad! Blimey! T' parachute only opened partially, 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. Well, blow me down! Blimey! T' rocket came in fairly fast and broke a fin off on landing. Well, blow me down! Blimey! Minor repairs are needed and t' rocket will be ready t' fly again.

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

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

CONs: None.