412 Differences
The BELL 412 Series grew like this: 212 + 2 more blades (bolted another pair with a flex-beam on top of the original pair!)= 412 Classic (useless and non-upgradable to the more powerful/capable DF engine and drivetrain). Better off with a 212! At least then you have a High Inertia Rotor rather than the Low (as in NO) Inertia Rotor of the 412!
412 Classic 'upgraded to 412 SP (SUPER POWER!!!) with slightly better design to stop the airframe cracking up, but still with the old 212's BF engines and inability (due airframe tolerances) to upgrade to DF engines and upgraded powertrain.
412SP then upgraded to HP (HIGH POWER!!-marginally better engine power with later model BF engines - a/c handles better but still only single AFCS). The HP models onward equipped with overtorque warning system (co-pilots always comes on first - go figure!). The HP is easily upgradable to DF engines - becoming in effect the best performing of the 412 series as it works out (with DF engines & associated powertrain upgrade) about 450 lbs on average below the 412 EP basic weight. Changes include strengthened main box, shaft and drivetrain, + upgraded (but more sensitive) Mast torque system (split-type torquemeter replaces the old BF engine/212 Delta Torque type indicator).
Most models now retrofitted to the newer 8 hour digital CVR system - so that the boss can hear everything!
Last Model:
The 412 EP (EXTRA/EXTREME/ENDLESS POWER) now comes standard with the DF engines, Upgraded trannie etc, yaw trim (useless Bell crap), Dual Digital AFCS as opposed to the old single steam-valve-driven item in the Classic/SP/HP - which makes all the difference for decent 3 axis/ 4 axis (SAR models) IFR flight. EP gives you dual digital FD selectors as opposed to the previous single analogue unit. New bells and whistles, twitchier pedal actuator, left/right N2 governor beeper trim (also retrofitted to upgraded DF engined HP models) functions only by tweaking #2 engine up or down a tad and primarily to fix torque splits inherent with the far more lively/twitchy/hotter starting DF FCUs! Better compass system and gyros. If you want you can get the very nice aircon upgrade with the new EPs - but at a 450 lbs penalty - making a DF equipped HP about 900 lbs less in basic airframe weight than the full-option new EP! Future US military variant is supposed to have FADEC, Glass cookpit (can't write it properly or it gets edited out!), improved (possibly Cobra Z) head and blades to replace the old boltontopoftheotherbastard Bell bodge (rather than a single in-plane starflex like the fwoggy machines) and a new quieter and more powerful tail rotor. Still to be seen yet though. Bell should just have taken their best biggest machine ever after the Huey (the 214B) and got Soloy to do a twin engine fit with 4 Burping Blades and and air conditioner!
The joy (!) of the DF-engined aircraft is their ability (with at least 5 to 8 knots of wind) to operate off a helideck at MAUW up to about 42 degrees C. Good enough for most places. The BF engined SP/HP will start to lose HOGE power/load lifting ability above about 34 to 38 degrees. They are noticeably less foregiving! The DF has single-growth crystal Hot-end blades - so has a much spicier top-end/OEI performance when the SH1T does hit the fan! All of the 412 series suffer from crappy pedal performance though in the hover, as that second bolt-on set of blades induces naughty interference to the tail rotor - nasty when the relative wind gets past the beam or the aircraft gets too high in the hover! 4 feet is really the safe max for hovering a 412! It ain't got the manners of the 205 or 212, sadly!
If you can - avoid the airline seat fit - there's nothing like the flexibility of the old troop seats - and customers eventually realize this!
Hope this makes everything as clear as muck!!!
Last edited by Oracle; 11th Sep 2006 at 19:50.
Reason: typos & censoring!