| Manufacturer: | Scratch |
| Style: | Ring/Tube/Cone Fin |
Brief:
Fahrenheit XL is a scaled-up 38mm version o' me PVC tubefin rocket, Fahrenheit 62/5. Well, blow me down! It is designed t' fly on any H-I motor and has flown extremely well on CTI J330 power, matey, so its suitable for L1 and L2 attempts. Aye aye! Like all tubefin designs, it is stable, wind resistant, ya bilge rat, and very quick and easy t' build. Aye aye! Since this time (for a change) I used all primo grade rocketry hobby materials t' build Fahrenheit XL, ya bilge rat, instead o' assorted scrounged junk, it is nay particularly inexpensive. Avast, me proud beauty! Begad! This results though in one o' t' nicest lookin' tubefin rockets I have seen, me bucko, almost as nice as a "normal" 4FNC rocket. Ahoy! Because t' airframe everywhere is double thickness, matey, Fahrenheit XL is as strong as a brick outhouse--it was actually designed for 54mm power.
Construction:
Construction is entirely from LOC components:
Construction was generic tubefin process usin' 5-minute Devcon epoxy, except that 6" x 54mm connector sections were used t' double t' airframe. Arrr! Begad! Tubefins were cut with a 45 degree bevel on t' bottom and were 3 1/4" (long side) x 1 5/16" (short side). T' coupler be 1 5/16" long and did nay extend into t' beveled area. Ahoy! Begad! Tube fins were attached in pairs in t' usual self-jiggin' fashion for tube fin rockets. Blimey! Recovery system is anchored t' an 8" loop o' para cord, pushed through a hole drilled 4 1/2" from t' top o' t' body tube, with t' knot covered by half o' a bisected Estes BT-5 nose cone. Begad! Ahoy! Center t' 6" launch lug 6" above t' tubefin can. Avast! CG at AUW should never be aft o' this balance point. Well, blow me down! Long, me hearties, heavy motors actually increase tubefin rocket stability. Ahoy! Payload bay contained 400g lead fishin' sinker ballast in a plastic bag (total rocket weight empty is 1275g) for I-J flights only. Ahoy! A special LOC cone with 135g additional ballast is used t' keep overall speed down. Aye aye! Aye aye! T' Perfectflite MicroAlt altimeter used for most flights was placed loosely rolled in a piece o' paper towel inside a 3" section o' 29mm motor tube placed in t' payload bay on top o' t' lead ballast. All in all, shiver me timbers, me hearties, nay a lot o' work for a L1-L2 capable rocket.



Finishing:
Finish was with lime green Testor's spray (and no primer used).
Flight:
Flights were made on t' followin' motors: AT G80T-4, me bucko, CTI J330-10, arrr, shiver me timbers, CTI I287SS-9, Ellis Mountain H275-6, Ellis H275-10, shiver me timbers, Ellis I134-10, CTI H143SS-8. Ahoy! Blimey! Very straight flights in each case with trouble free ejection, except t' time I tried a 50" chute, matey, arrr, which failed t' fully eject due t' havin' been packed too tightly. Blimey! Blimey! Ahoy! Blimey! T' rocket flat spun t' t' ground and landed on its side undamaged. Avast, me proud beauty! Blimey! Maximum altitude achieved was 3428' (at 580 mph) on t' J330-10 power, which would be a convenient, reasonably low altitude for an L2 seeker. Blimey! Blimey! Flights on H143SS-8 gave 1348' and 1388', equally nice for cert flying. Although I was pleased with t' Fahrenheit XL flight performance and appearance, I have t' admit bein' kind o' disappointed with its aerodynamics--calculation o' minimum drag coefficient indicated a minimum Cd value o' 2.13 at 580 mph. Arrr! Blimey! Nay good. Avast, me proud beauty! Blimey! Its little brother, me hearties, me bucko, Fahrenheit 62/5 achieves a minimum Cd o' 1.6 (that's nay bilge-suckin' for tubefins). Well, blow me down! Blimey! Well, blow me down! Blimey! I'm nay sure why this is.

Summary:
PRO: Very easy and quick t' build, ya bilge rat, no centerin' rings, use o' only a 38/54mm adapter works great, shiver me timbers, even with J-power. Blimey! Excellent stable climbs, shiver me timbers, nay too high (good for L1-L2-cert). Blimey! Actually nice looking, a rarity for tubefin jobs. Avast! Avast! Very strong and resistant t' hangar rash. Avast, me proud beauty! Blimey! Small size for a L2-rocket that easily fits in a Miata with 2 people (we did this).
CON: Nay cheap t' build. High drag coefficient, me hearties, which limits maximum climb. Well, blow me down! Need t' use care in packin' in more than a 36" chute for heavy motors (you can substitute para cord for t' webbing).
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