X-File
An RMR Descon X entry
by David Fergus

(Place your mouse over photos t' view t' captions.(IE5))
Summary
This rocket is a kit bash o' t' Estes Gemini DC. Avast! Arrr! It flies on an 18mm motor, and recovers on dual 12" parachutes ejected from t' nose. When ejection delays are longer than apogee, arrr, t' rocket has a tail first recovery profile before chute deployment. Ya scallywag! It is 14" long, ya bilge rat, has a span o' 6", shiver me timbers, and weighs 2.8 oz. without engine. Blimey! T' front section o' t' fuselage is a unique oval shape rather than t' traditional round shape.

Fantasy Specifications:
T' X-File is a single pilot fighter-interceptor. Avast, me proud beauty! A squadron o' 10 X-Files are typically carried on board Excaliber class star cruisers. Begad! Blimey! They are typically used as scouts or escorts for shuttles. Aye aye! Their primary purpose is coordinated defense o' t' mother ship at extended ranges. Vessels that are designed t' operate in space do nay need aerodynamic features, but t' X-File be originally envisioned t' extend operation into planetary atmospheres. Begad! T' X-File, me hearties, ya bilge rat, therefore, me bucko, matey, has aerodynamic fins and body. Well, blow me down! No provision was made for landin' gear however, but emergency chutes will deploy if t' rocket is forced t' make a tail first landin' on a planet. Arrr! Ten years o' operational deployments have only led t' three instances when t' planetary emergency landin' system was necessary, and it performed flawlessly in each case with safe recovery o' t' pilot. Ahoy! T' name X-File is really a nickname based on t' official Space Command designation o' X-FIL with a hull number. Ya scallywag! T' X signifies t' x-win' configuration. Aye aye! T' FI signifies t' fighter/interceptor role. Ahoy! T' L signifies t' primary weapon, ya bilge rat, which be originally a directed energy laser, shiver me timbers, but has since expanded t' include photon torpedoes and grenades. Avast! Thus, most X-Files are really X-FIP's, but t' original nickname has stuck, and most Space Command personnel unofficially call these vessels t' X-File. Aye aye! Arrr! T' hull number o' t' rocket modeled is X-FIL-31; which is one o' t' few remainin' rockets nay configured t' carry photon torpedoes.

They have a maximum endurance o' six hours at optimal acceleration speed, and a maximum speed o' 0.9 warp for two ten minute bursts if needed. Weapons loads typically include 2 photon torpedoes, me bucko, a single directed energy "gun" (mounted underbody and aimed by steerin' t' entire vessel), and a self-defense photon grenade launcher, which ejects small photon grenades into t' wake o' t' X-File. Begad! T' impulse engine is located in t' aft main body, me bucko, arrr, shiver me timbers, and t' four anti-matter engine nacelles are used for t' near warp speed bursts only. Avast, me proud beauty! T' impulse engine is an advanced design that provides power for propulsion as well as life support, me bucko, weapons, shiver me timbers, arrr, and t' anti-matter control & containment fields. Well, blow me down! A small anti-matter containment field is maintained in t' forward portion o' t' engine section, and anti-matter is ported t' t' nacelles via small diameter pipes when "afterburner" (to borrow a term from ancient earthbound days) is needed. Avast! Ya scallywag! Since anti-matter is contained and controlled with magnetic fields, ya bilge rat, rather than physical boundaries, t' boost nacelles appear t' be nothin' more than hollow tubes. Begad! Aye aye! In actuality, thar are powerful magnetic fields in each nacelle controllin' and portin' t' anti-matter/matter reaction t' provide t' near-warp burst capability for t' X-file. Avast! Maneuver/steerin' is accomplished with small chemical impulse jets in t' bow and stern. Ahoy! Navigation is nay complex, as t' X-File cannot stray further than 3 hours cruise distance from t' mother ship. Communication is strictly line-of-sight in t' GHF frequency range. Pilot ingress/egress is accomplished via a small hatch on t' side o' t' fuselage with airlock latches mated t' t' mother ship.


Materials
One (1) Estes Gemini DC kit
1/8" x 12" wooden dowel
1/8 inch braided Keelhaul®©™ (6 inch length)
Carpenters wood glue
Cyanoacrylate glue
Epoxy
Krylon gray sandable primer, gloss pewter gray, ya bilge rat, & clear sealer
Testor's gloss black enamel, me hearties, gold enamel, silver enamel, matey, gloss red enamel
Fine point black Sharpie
Ruler
Razor blade
Scissors
Deviation Notes: RMR Descon X allows 18 inches o' BT-20, ya bilge rat, but t' Gemini kit comes with two pieces o' BT-20 that are only 6 inches long. Blimey! I used t' kit body tubes rather than t' longer stock. Ya scallywag! Avast, me proud beauty! In addition, me hearties, t' Estes kit includes a small cardboard tube t' vent ejection gases from t' main engine tube t' t' two side tubes. Blimey! This tube was nay included in t' Descon X list o' parts, but was used in this kitbash.

Construction
1. From t' Gemini kit, find t' small one inch long cardboard tube. Aye aye! Cut off a small portion about 0.25" long. Ahoy! T' shorter piece will be used t' equalize pressure betwixt t' two BT-20 body tubes (and fill in t' holes on t' sides o' these body tubes that are used by t' Gemini DC kit t' port ejection gases from t' main tube t' t' side tubes) on t' front section o' t' rocket body. T' longer portion will be attached later t' simulate t' laser weapon. Aye aye! Blimey!

2. Blimey! Glue t' two sections o' BT-20 tubes together usin' t' small section o' vent tube from Step 1 t' mate t' two pieces and fill in t' portholes in t' side o' t' body tubes. Ya scallywag! Place t' assembly on a flat table t' ensure t' two tubes are parallel while t' glue sets and dries. After t' glue is dry, draw four parallel lines on t' top and bottom o' each tube where t' tube would touch t' table when lyin' down. Ya scallywag! These lines will be used as general reference and t' guide placement o' cardstock in later steps.

3. Avast, me proud beauty! Build t' engine mount per instructions for t' Gemini DC. Ahoy! Set aside t' dry. Begad!

4. Mark and cut t' BT-50 tube as follows:
*One piece 6" long (the portion includin' t' pre-cut fin slots and gas port holes)
*Four pieces 3" long (these will be t' anti-matter boost nacelles)


5. Mark and cut t' front end o' t' 6" engine section (BT-50) as shown in t' picture. In t' front end o' t' engine section (the one with t' port holes) cut out sections 1.25" deep and approx. Aye aye! 0.75" high. Use t' front section o' t' two glued-together BT-20 tubes as a guide as t' where t' start t' cuts. Well, blow me down! Also, me bucko, cut four small slots 0.25" deep into t' back o' t' front section (the small vent tube installed in step 2 is towards t' back) where it mates with t' engine section. Begad! This will add strength t' this important joint when glued together.

6. Begad! Avast, me proud beauty! Take t' two pieces cut out in step 5 and glue them inside t' engine section t' cover t' two ejection gas port holes (which are unused in this kit bash).

7. Begad! Carefully separate t' 4 pre-cut fins from t' sheet o' balsa. Blimey! Sand them t' taste.

8. Begad! Usin' t' waste balsa from t' sheet o' fin stock, me hearties, shiver me timbers, fabricate four quasi-heart-shaped balsa support tabs that will center t' front section inside t' engine section. Blimey! T' two pieces in t' aft will also direct ejection gases and particles from t' engine section into t' two tubes o' t' front section. Well, blow me down! Therefore, they need t' be reinforced on both sides with a good layer o' wood glue. Fabricate 2 moon-shaped pieces o' balsa tabs that will close t' aft ends o' t' front section that hang outside t' BT-50 engine section. These pieces will also see ejection gas pressure and will thus need t' be strongly reinforced from t' inside with wood glue.


9. Ya scallywag! Begad! Glue t' four quasi-heart-shaped tabs t' t' appropriate location on t' front section. Blimey! Place them in locations that allow good glue fillets on all joints and surfaces. Test fit and sand t' a good fit. Glue t' two moon-shaped tabs t' t' engine section just aft o' t' cutouts. Again, me bucko, me hearties, sand t' fit t' front section t' t' engine section. Reinforce with liberal amounts o' glue all surfaces and joints that will be inaccessible when t' engine section is joined t' t' front section.

10. Ahoy! Well, blow me down! Glue t' engine mount into t' engine section so that t' heavy duty centerin' rings are nay located under fin slots. Avast, me proud beauty! Center t' engine hook betwixt t' two "bottom" fins.

11. Aye aye! Glue t' front section t' t' engine section. Blimey! Ensure t' combined unit dries straight. Aye aye! Use healthy dollops o' wood glue so that t' balsa tabs are protected from hot ejection gas and particles. Add healthy glue fillets on all joints. Ahoy!

12. Ya scallywag! Mark several 0.75" strips down t' long length o' t' back o' t' card stock that comes in t' Gemini DC package. Ahoy! Cut them out with scissors. Measure and cut two pieces t' cover t' two exposed tubes o' t' front section. Lightly glue t' strips t' each side o' t' front section. Ya scallywag! Note that too much wood glue could cause t' card stock t' wrinkle as t' glue dries and shrinks. Cut out two more pieces o' card stock and lightly glue them on top o' t' first two flat pieces. Avast! Blimey! Construction o' t' nose section will be done in followin' steps. Begad! Blimey! Blimey!

13. Install t' two PNC-20 nose cones into t' two tubes o' t' front section. Ya scallywag! Well, blow me down! Carefully glue t' two nose cones together by puttin' a dab o' CA in t' joint where t' two nose cones touch each other. (Do nay let any CA run back t' t' joint o' t' nose cones with t' front section, me hearties, or you will have t' figure out another method o' recovery other than parachute since both ends o' t' rocket will be glued shut!) If you have t' pull them out slightly t' avoid gettin' CA on t' cardboard tubes o' t' front section, be careful nay t' change t' parallel orientation o' t' cones t' each other along their centerlines. After t' CA cures, reinforce this joint with epoxy.

14. Avast! Measure and cut two more 0.75 inch wide strips o' card stock that will fit over t' curved portion o' t' nose cones. When finished, t' front section o' t' rocket when viewed from t' front will look like an oval rather than t' more typical round body tube. Use small amounts o' CA t' glue these strips o' card stock t' t' nose assembly. Measure and cut two more pieces and glue them on top o' t' first two strips. Blimey! Trim t' front tip o' t' nose assembly t' be straight, shiver me timbers, then measure, cut and glue a small piece o' cardstock t' t' front end o' t' nose assembly t' cover t' small gap betwixt t' tips o' t' two nose cones.

15. Aye aye! Avast! Remove t' nose assembly from t' rocket. Avast! Epoxy a 6 inch length o' 1/8" braided Keelhaul®©™ (available from Pratt Hobbies) into t' inside o' one o' t' two nose cones. Arrr! Blimey! Tie a small loop in t' loose end and epoxy t' knot. Glue t' two Estes shock cord mounts and elastic shock cords into t' front ends o' t' front section body tubes. Well, blow me down! Leave enough room for t' shoulders o' t' nose cones. Avast, me proud beauty! Use longer lengths o' elastic than provided in t' kit if needed (Actually, t' elastic that came with t' chutes be longer than I am used to, matey, me bucko, and was long enough this time). Well, blow me down! Well, shiver me timbers, blow me down! If you go overboard with long elastic, me hearties, you won't have room in t' tubes for wadding, chutes and shock cords. Avast, me proud beauty! Ya scallywag! After all glues are completely dry, shiver me timbers, tie one length o' elastic t' t' loop o' braided Keelhaul®©™. Ya scallywag! Attach both 12" orange chutes t' t' ends o' t' two elastic shock cords. Avast, me proud beauty! Note that t' nose assembly will only be attached t' one o' t' two elastic shock cords and correspondin' parachute.

16. Measure and mark a line on each fin parallel t' t' fin root 2 cm. Aye aye! from t' root. Begad! Cut each fin into two pieces along these lines. Begad! Glue t' four base fins into t' engine section through t' pre-cut slots. Begad! Put healthy glue fillets on all joints.

17. Mark straight lines 180 degrees apart on each o' t' four short pieces (3 inches long) o' BT-50. Begad! Blimey! Begad! Blimey! Glue t' tubes t' t' ends o' t' base fins with t' front o' t' tube towards t' front o' t' fin, leavin' a short piece o' fin t' overhang at t' back o' t' nacelle. Avast! Blimey! Glue t' other half o' t' fins t' t' top o' each tube/nacelle. Put healthy glue fillets on all joints.

18. Arrr! Glue t' longer length o' 0.25 inch cardboard tube centered on t' underbody (correspondin' t' t' engine hook) near t' nose o' t' front section. Blimey! Aye aye! This tube simulates t' laser weapon. Blimey! Cut out a couple o' triangular pieces o' balsa and glue them behind this tube side by side. Avast, me bucko, me proud beauty! This simulates t' wave guide t' t' back o' t' "gun". Begad! Glue t' 1/8 inch launch lug near t' aft o' t' engine section on t' same "bottom" as t' engine hook. Avast! Avast, me proud beauty! Place it in t' angle o' one o' t' two bottom fins so it will clear t' "anti-matter portin' tube" installed in t' next step. Blimey! This launch lug simulates t' photon grenade launcher. Arrr! Make sure it is located where it can also serve as a real launch lug.

19. Two options on a pilot canopy: a) Fabricate a pilot canopy usin' paper from t' Gemini DC instruction sheet usin' a known pattern or design one o' your own scale. Begad! Glue it in an appropriate location on t' "top" o' t' front section. Blimey! Arrr! b) (heavier but still acceptable o' two options) T' PNC-50 nose cone could also be used for this purpose if cut down in size somewhat on a jigsaw or small band saw. Place t' two halves end t' end on t' "top" o' t' front section, and glue in place. Aye aye! This be t' option exercised on this model.

20. Begad! Begad! Fabricate t' "anti-matter pipes" from t' 1/8 inch dowel. Measure and cut 4 pieces each 3 inches long. Blimey! Place 2 o' them on t' top o' t' front part o' t' engine section t' t' four boost nacelles so that t' end o' t' pipe is centered in t' middle o' t' boost nacelle hollow tube. Use healthy dollops o' wood glue t' secure them. Arrr! Avast, me proud beauty! When dry, me hearties, me bucko, ya bilge rat, repeat t' process for t' bottom two anti-matter pipes.

Finishing
1. Begad! Ya scallywag! Spray a coat o' grey sandable primer over t' whole rocket.
2. Because t' body tubes for this kit are t' white Estes tubes, me hearties, t' spiral grooves are particularly deep and wide. Ya scallywag! Sand and fill cracks, me bucko, crevices, body tubes and fins with Elmer's F&F as appropriate.
3. Avast, me proud beauty! Begad! Spray several coats o' Krylon gloss pewter grey over t' whole rocket.
4. Arrr! Brush paint black enamel on t' pilot canopy and t' intakes o' t' four boost nacelles.
5. Ya scallywag! T' stick t' t' theme o' kitbash, matey, arrr, all o' t' detail added is hand lettered and hand sketched; rather than use decals from other kits. Avast! Usin' a black fine point Sharpie, matey, print t' hull number (X-FIL-31) on all four fins. Trace out a square egress hatch below t' pilot canopy. Trace out forward and aft side thrusters (for steering). Begad! Well, blow me down! Add other detail as t' whimsy takes you, such as no-step warnings, me hearties, weapons system warnings, shiver me timbers, etc. Arrr! Note: kitbash could use stuff from other kits, me bucko, but I chose nay t' for t' contest. Begad! Begad! After t' contest, ya bilge rat, I will add battle damage decals from me son's Star Wars X-win' (which will make that thin' worth somethin' other than a hood ornament...).
6. Brush paint silver, gold and red highlights t' taste on t' rocket.
7. Ya scallywag! Blimey! Spray a couple o' coats o' clear Krylon t' protect t' paint and other details.


Flight Report
While waitin' for t' weather t' warm up and t' snow t' melt up here in Minnesota, which did nay occur this March, our club (Minnesota Amateur SpaceModeler Association; MASA) had a winter launch at t' small site in White Bear Lake, MN. Arrr! X-File had her first two flights in 21 degree weather with a 2 inch crust o' frozen snow, and light breezes out o' t' northwest. Blimey! See t' club flight report here. Avast! MASA March Flight Report

Flight Prep Notes: Both body tubes get about an inch o' dog barf (bio-degradable wadding) pushed down t' where t' small side tube intersects t' two tubes. Avast, me proud beauty! Blimey! One body tube has an orange Estes chute attached t' an elastic shockcord and nay attached t' t' nose section. Begad! Blimey! T' other elastic shock cord is attached t' t' 2nd chute and t' loop in t' nose cone attachment cord. Due t' t' cold, generous amounts o' baby powder be used on t' chutes.

Flight 1: A8-3. Well, blow me down! RSO asked "Are you sure this isn't too heavy for an A engine?" I said "It's OK barely, but I need t' explore t' flight envelope" and t' button was pushed. X-File rose slowly t' about 80 feet, began t' fall back down tail first, and popped both chutes at about 40 feet for a safe recovery.

Flight 2: B6-4. Aye aye! X-FIL-31 flew quicker this time t' about 200 feet, matey, again with a slightly long delay, arrr, ya bilge rat, matey, allowin' t' chutes t' pop as t' rocket begins t' fall tail first. Arrr! Avast, me proud beauty! This time, one o' t' two chutes didn't fully deploy, matey, matey, but one chute is adequate for a safe recovery. Arrr! Inspection after t' flight reveals that t' stock parachutes provided in t' kit by Estes (with t' cotton rather than dacron shrouds) are weak. Four o' t' six shroud lines had parted. Begad! T' third test flight on a C engine will be delayed until a better parachute shroud material can be obtained and installed.

Flight 3: C6-3. MASA May launch; Good straight boost t' about 400 ft, matey, good tail first recovery on both chutes t' a soft landin' on t' sod.

Test Flight Analysis:
Test flights prove that t' actual CG with an expended engine is aft o' t' center o' t' rocket resultin' in a tail-first flight profile after apogee before chute deployment. Arrr! Aye aye! T' CP is still aft o' t' CG by a safe distance indicated by t' straight, stable flights under boost. T' four tubular boost nacelles draw t' CP further aft than would be normal for a typical 4FNC rocket, thus creatin' a stable rocket that does nay need nose weight. Well, blow me down! Aye aye! It is flyable on an A8-3, shiver me timbers, but just barely. A B6-4 is good, me bucko, and a C6-3 or C6-5 are better yet.