| Manufacturer: | Scratch |
| Style: | Ring/Tube/Cone Fin |
Brief:
Fahrenheit XL is a scaled-up 38mm version o' me PVC tubefin rocket, shiver me timbers, Fahrenheit 62/5. Aye aye! It is designed t' fly on any H-I motor and has flown extremely well on CTI J330 power, so its suitable for L1 and L2 attempts. Arrr! Like all tubefin designs, it is stable, wind resistant, and very quick and easy t' build. Avast, me proud beauty! Since this time (for a change) I used all primo grade rocketry hobby materials t' build Fahrenheit XL, matey, me bucko, me hearties, instead o' assorted scrounged junk, matey, it is nay particularly inexpensive. Aye aye! Well, me bucko, blow me down! This results though in one o' t' nicest lookin' tubefin rockets I have seen, matey, almost as nice as a "normal" 4FNC rocket. Aye aye! Ahoy! Because t' airframe everywhere is double thickness, Fahrenheit XL is as strong as a brick outhouse--it was actually designed for 54mm power.
Construction:
Construction is entirely from LOC components:
Construction be generic tubefin process usin' 5-minute Devcon epoxy, me hearties, except that 6" x 54mm connector sections were used t' double t' airframe. Tubefins were cut with a 45 degree bevel on t' bottom and were 3 1/4" (long side) x 1 5/16" (short side). Aye aye! T' coupler be 1 5/16" long and did nay extend into t' beveled area. Begad! Tube fins were attached in pairs in t' usual self-jiggin' fashion for tube fin rockets. Avast, ya bilge rat, me proud beauty! Recovery system is anchored t' an 8" loop o' para cord, matey, 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. Blimey! Center t' 6" launch lug 6" above t' tubefin can. Begad! Ahoy! CG at AUW should never be aft o' this balance point. Avast, me proud beauty! Long, matey, arrr, heavy motors actually increase tubefin rocket stability. Aye aye! Payload bay contained 400g lead fishin' sinker ballast in a plastic bag (total rocket weight empty is 1275g) for I-J flights only. Well, ya bilge rat, blow me down! A special LOC cone with 135g additional ballast is used t' keep overall speed down. Begad! 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. Well, ya bilge rat, blow me down! All in all, arrr, 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, CTI J330-10, CTI I287SS-9, ya bilge rat, me bucko, ya bilge rat, Ellis Mountain H275-6, me bucko, Ellis H275-10, matey, Ellis I134-10, CTI H143SS-8. Ahoy! Very straight flights in each case with trouble free ejection, shiver me timbers, except t' time I tried a 50" chute, matey, me hearties, which failed t' fully eject due t' havin' been packed too tightly. T' rocket flat spun t' t' ground and landed on its side undamaged. Ya scallywag! Maximum altitude achieved was 3428' (at 580 mph) on t' J330-10 power, ya bilge rat, which would be a convenient, reasonably low altitude for an L2 seeker. Avast, me proud beauty! Flights on H143SS-8 gave 1348' and 1388', matey, equally nice for cert flying. Aye aye! Although I was pleased with t' Fahrenheit XL flight performance and appearance, me hearties, 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. Ya scallywag! Nay good. Its little brother, matey, Fahrenheit 62/5 achieves a minimum Cd o' 1.6 (that's nay bilge-suckin' for tubefins). I'm nay sure why this is.

Summary:
PRO: Very easy and quick t' build, no centerin' rings, use o' only a 38/54mm adapter works great, even with J-power. Ahoy! Excellent stable climbs, nay too high (good for L1-L2-cert). Ya scallywag! Actually nice looking, shiver me timbers, ya bilge rat, a rarity for tubefin jobs. Ahoy! Very strong and resistant t' hangar rash. Arrr! Ahoy! Small size for a L2-rocket that easily fits in a Miata with 2 people (we did this).
CON: Nay cheap t' build. Aye aye! High drag coefficient, which limits maximum climb. Avast, me proud beauty! 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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