Bell 212
Yes Thud....and only because the Mob required it.....not when left to the Weasels in Redhill....trust me ....heard it from the Horse's Mouth....(really the mouth). From a former Regional Flying Superintendent now retired.
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FlightSafety can do 212 FAA type training in their simulator.
They are also able to offer JAA type ratings (all in simulator) for S76 and B430 simulator but the 212 is/was not currently CAA/JAA approved.
SAS Flight Academy have the only 212 simulator in Europe so you could try them.
The only company in the UK who own and operate 212 is Bristow.
I'd take the bonding......... 3 years will pass real quick and save you a pile of money paying for your own type training.
Hope that helps
They are also able to offer JAA type ratings (all in simulator) for S76 and B430 simulator but the 212 is/was not currently CAA/JAA approved.
SAS Flight Academy have the only 212 simulator in Europe so you could try them.
The only company in the UK who own and operate 212 is Bristow.
I'd take the bonding......... 3 years will pass real quick and save you a pile of money paying for your own type training.
Hope that helps
Can't you buy yourself out of the bond, if necessary ? Save you finding the money up front immediately. Get the training, go in for the three years and if you absolutely hate the place, buy yourself out - worry about finding the money then.
Why pay for the type rating, unless it's a pre-requisite for the job? Cross the bond bridge if and when you get to it! Even if you stay in the job for a short period chances are they'll only slug you a pro-rata bond amount and not the full cost. And as for an FAA B212 type rating, I thought the rotorcraft helicopter type rating covered all small and medium size helicopters (twin and single)??
Vertical fin on AB-212
I can't seem to get the true explanation for this one. Its about AB-212's front vertical fin (fwd of main rotor mast). What is its function. I picked up some theorys that it's a stabilizer, others say it's a de-stabilizer. What is it for?
Last edited by Phoinix; 26th Aug 2012 at 13:24.
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Yes, that fin would destabilize yaw somewhat, but most helos have lots of yaw stability (because the tail rotor behaves like a piece of fin. It produces thrust when yawed that restores the trim. In fact, the tail rotor produces about 4 to 8 times the thrust of an equivilent vertical fin!
More importantly that big forward fin would add dihedral, which is the roll you get when you yaw. IFR handling requirements state that when you put in some pedal to yaw, you must have to put in some opposite roll cyclic to counter the roll that the aircraft naturally has. In other words, some right pedal to produce a few degrees of yaw must produce some right rolling attitude change. This right roll must therefore require the pilot to put in some left cyclic to trim the aircraft level.
That big fin above the roll center would create a roll force above the roll centerline that would create a right roll when a right yaw is put in.
The reason it is there is probably to allow the minimum IFR speed to be reduced somewhat, since the natural dihedral stability of most helicopters vanishes at about 60 to 70 knots. What is Vmin IFR in that 412's flight manual?
More importantly that big forward fin would add dihedral, which is the roll you get when you yaw. IFR handling requirements state that when you put in some pedal to yaw, you must have to put in some opposite roll cyclic to counter the roll that the aircraft naturally has. In other words, some right pedal to produce a few degrees of yaw must produce some right rolling attitude change. This right roll must therefore require the pilot to put in some left cyclic to trim the aircraft level.
That big fin above the roll center would create a roll force above the roll centerline that would create a right roll when a right yaw is put in.
The reason it is there is probably to allow the minimum IFR speed to be reduced somewhat, since the natural dihedral stability of most helicopters vanishes at about 60 to 70 knots. What is Vmin IFR in that 412's flight manual?
We used to have a Bell 212 with Bristows on the North Sea with one of those fins, registration number was G-BIGB, Big B. The fin was there, I believe, because it had originally been registered in the USA, and had been an FAA requirement for IFR. It was subsequently removed, although I do recall seeing other American-registered 212's without the fin.
Vmin IMC for the 212 is 40 kts
Vmin IMC for the 212 is 40 kts
That is it, thanks Nick. That explanes a lot.
So, in general it counteracts that "nose left", when applying right pedal and so, making a heli more stable around the longitudinal axis during turns at lower speeds.
But doesn't the downwash of main rotor somewhat disable the flow around the fin - especialy at lower speeds?
I'm not sure about Vmin IFR on 412, but i will check.
Our AB-212 was built in Italy, and it came with that fin from the factory.
So, in general it counteracts that "nose left", when applying right pedal and so, making a heli more stable around the longitudinal axis during turns at lower speeds.
But doesn't the downwash of main rotor somewhat disable the flow around the fin - especialy at lower speeds?
I'm not sure about Vmin IFR on 412, but i will check.
Our AB-212 was built in Italy, and it came with that fin from the factory.
Last edited by Phoinix; 12th Jun 2004 at 15:05.
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Phoinix, I wasn't clear enough. It counteracts the roll left with right pedal, which is unstable, and not allowed for IFR flight. It does reduce yaw stability, but my guess is there is lots of yaw stability from the basic aircraft layout, so they can give some away to get some dihedral stability.
The rotor downwash is a factor, but might actually help, because the velocity of the combined free stream air and the rotor wash could be even more forceful than the free stream alone.
I'll bet this thing was hung there by trial and error, probably in desparation during the flight test program when the data came out that said the aircraft won't meet the regs. Most of those little fins and fences on wings, tails, tail cones and the like get pasted on as the aircraft is tested, and they are put there by flight test guys who then laugh at the designer's mistakes.
the interplay between testers and designers is fun to watch!
Here is a nice discussion of why dihedral works:
http://members.rogers.com/maxf/ftaf3.pdf
The rotor downwash is a factor, but might actually help, because the velocity of the combined free stream air and the rotor wash could be even more forceful than the free stream alone.
I'll bet this thing was hung there by trial and error, probably in desparation during the flight test program when the data came out that said the aircraft won't meet the regs. Most of those little fins and fences on wings, tails, tail cones and the like get pasted on as the aircraft is tested, and they are put there by flight test guys who then laugh at the designer's mistakes.
the interplay between testers and designers is fun to watch!
Here is a nice discussion of why dihedral works:
http://members.rogers.com/maxf/ftaf3.pdf
Last edited by NickLappos; 12th Jun 2004 at 15:07.
Yes, of course. My bad. I undesrtood it the first time, but had problems expressing that 
BTW: thanks for that refreshing article on dihedral.
BTW: thanks for that refreshing article on dihedral.
Last edited by Phoinix; 13th Jun 2004 at 19:04.
Sez Nick:
Yes, very interesting discussion of fixed-wing dihedral effects.
An airplane with zero dihedral would exhibit very little yaw/roll coupling. Also, airplanes do not have a hinge where the wings and fuselage meet, as the 212 does.
So how does a discussion of dihedral relate to helicopters? Or I guess my question is "how much dihedral does a helicopter rotor have?"
Here is a nice discussion of why dihedral works:
http://members.rogers.com/maxf/ftaf3.pdf
http://members.rogers.com/maxf/ftaf3.pdf
An airplane with zero dihedral would exhibit very little yaw/roll coupling. Also, airplanes do not have a hinge where the wings and fuselage meet, as the 212 does.
So how does a discussion of dihedral relate to helicopters? Or I guess my question is "how much dihedral does a helicopter rotor have?"
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Pprunefan,
Actually, we use the term dihedral to describe the effect (when a yaw makes a roll) and can be measured on airplanes, helicopters and even ships! the paper describes wings but the effect is the same.
For helicopters, lost of stuff happens in the rotor, as you describe, like flaping and stuff. The rotor dsk is also coned just like an airplane's wing, so there is a contribution there as well.
But, helicopters generally have strong dihedral due to the way the rotor behaves when we impose a new wind direction on it. If you can, picture the rotor having been trimmed with the cyclic forward at high speed, so that the disk is level and the nose is down to trim at that speed. Then simply rotate that helicopter a bit to the right, like a right yaw would do. If you look at the rotor from the wind's perspective, where the air meets the disk as the new forward, you can see that the cyclic is now trimmed to the right relative to the airflow, so it has a small roll input. this makes the aircraft roll in the direction of yaw, so-called positive dihedral.
the problem with helicopters is that they fly at very low speeds. By the time you slow to 50 or 40 knots, the small effect I describe above is lost in the mud, and there is little dihedral for small angles of yaw. This is often the problem that sets the low speed Vmimi limit for helicopters. that big fin on the rook probably helps get some traction at low speed to add some roll, and perhaps gets the dihedral effect back at 40 or 50 knots, allowing Vmimi to be set lower. VFR aircraft don't need it, of course, since that dihedral requirement is an instrument thing.
Actually, we use the term dihedral to describe the effect (when a yaw makes a roll) and can be measured on airplanes, helicopters and even ships! the paper describes wings but the effect is the same.
For helicopters, lost of stuff happens in the rotor, as you describe, like flaping and stuff. The rotor dsk is also coned just like an airplane's wing, so there is a contribution there as well.
But, helicopters generally have strong dihedral due to the way the rotor behaves when we impose a new wind direction on it. If you can, picture the rotor having been trimmed with the cyclic forward at high speed, so that the disk is level and the nose is down to trim at that speed. Then simply rotate that helicopter a bit to the right, like a right yaw would do. If you look at the rotor from the wind's perspective, where the air meets the disk as the new forward, you can see that the cyclic is now trimmed to the right relative to the airflow, so it has a small roll input. this makes the aircraft roll in the direction of yaw, so-called positive dihedral.
the problem with helicopters is that they fly at very low speeds. By the time you slow to 50 or 40 knots, the small effect I describe above is lost in the mud, and there is little dihedral for small angles of yaw. This is often the problem that sets the low speed Vmimi limit for helicopters. that big fin on the rook probably helps get some traction at low speed to add some roll, and perhaps gets the dihedral effect back at 40 or 50 knots, allowing Vmimi to be set lower. VFR aircraft don't need it, of course, since that dihedral requirement is an instrument thing.
In my alcohol ravaged brain...remains the thought that the Bell Scas system (FAA rules) required the Dihedral Sail (or Fin) for the IMC kit. The Sperry system and the Sfena system (a real piece of fecal matter) did not require that device. The CAA in its infinite wisdom did not require the installation of the fin. Having flown all the variants...with my usual boxing glove control touch....I could not see any difference in the way the machines handled....unless you had the collective/yaw pedal interconnect that the Bell SCAS system offered. That allowed one's feet to get very idle in that collective movement was linked to the pedals thus TRE's could then keep the aircraft somewhat in trim. The interesting part came during hydraulic's off flight....when the pedals moved opposite of what you expected due to the interconnecting linkage.
Well now Ah'm just totally corn-fused. Maybe Ah'll never understand these helicopter thingees. See, Ah'm jus' a simple ol' country-boy pilot, but Ah takes some eck-sepp-see-ohn to the following statement.
Nick sez:
An airplane wing has a hard and very well defined leading edge over which the air flows. Helicopters have no such device. Once a helicopter rotor is in forward flight it doesn't have any clue as to where "straight ahead" is. Nor does it care. You simply *cannot* fly a rotor "out of trim" like you can a fixed wing. You can fly the fuselage out of trim, but this has absolutely no effect on the wind that the rotor is seeing.
In my aeroplane, if I'm scooting along in cruise and I push on the right rudder, the plane will most assuredly bank immediately and turn to the right. In my helicopter, if I do the same thing the fuselage will merely slew off to the right, the trim ball will slide out to the left, but the helicopter's track across the ground will remain fairly unchanged (banking the rotor is the only way to change direction). In fact, if I persist in pushing the right pedal, the helicopter will perhaps take on a bank to the left, which is how the ship normally behaves when the trim ball is displaced thataway, which is also the opposite of my airplane.
Maybe larger helos with articulated rotor systems behave differently than the small ships I fly. But I have demonstrated this time and time again to the non-believers. They freak out when I do this, fearful as they are (and legitimately so) of mast-bumping as we reduce the hub clearance in the 206. Perhaps they remember all those Cobra accidents that occurred until we learned the importance of diligent attention to yaw-trim in high-speed helicopters with teetering rotors.
If helicopters did indeed have "positive dihedral effect," then pushing on a pedal would cause a bank in that direction. But this does not happen.
What this tells me is that so-called "dihedral effect" in small helicopters is either non-existant or opposite to fixed-wing. Nick evidently agrees with me. In clarifying a previous post where he was talking about the behavior of the "shark fin" attached to the fuselage roof of the Bell 212, he writes:
Roll left with right pedal? Yeah, that's exactly what I've been saying all along. We do not need to be test pilots to witness this. Merely go up in cruise, and perfectly trim the aircraft. Now slightly press on a pedal (your choice- but not too much!), just enough to get the aircraft out of trim. DO NOT MOVE THE CYCLIC. Come back and tell me which way the helicopter banks.
Nick sez:
But, helicopters generally have strong dihedral due to the way the rotor behaves when we impose a new wind direction on it. If you can, picture the rotor having been trimmed with the cyclic forward at high speed, so that the disk is level and the nose is down to trim at that speed. Then simply rotate that helicopter a bit to the right, like a right yaw would do. If you look at the rotor from the wind's perspective, where the air meets the disk as the new forward, you can see that the cyclic is now trimmed to the right relative to the airflow, so it has a small roll input. this makes the aircraft roll in the direction of yaw, so-called positive dihedral.
In my aeroplane, if I'm scooting along in cruise and I push on the right rudder, the plane will most assuredly bank immediately and turn to the right. In my helicopter, if I do the same thing the fuselage will merely slew off to the right, the trim ball will slide out to the left, but the helicopter's track across the ground will remain fairly unchanged (banking the rotor is the only way to change direction). In fact, if I persist in pushing the right pedal, the helicopter will perhaps take on a bank to the left, which is how the ship normally behaves when the trim ball is displaced thataway, which is also the opposite of my airplane.
Maybe larger helos with articulated rotor systems behave differently than the small ships I fly. But I have demonstrated this time and time again to the non-believers. They freak out when I do this, fearful as they are (and legitimately so) of mast-bumping as we reduce the hub clearance in the 206. Perhaps they remember all those Cobra accidents that occurred until we learned the importance of diligent attention to yaw-trim in high-speed helicopters with teetering rotors.
If helicopters did indeed have "positive dihedral effect," then pushing on a pedal would cause a bank in that direction. But this does not happen.
What this tells me is that so-called "dihedral effect" in small helicopters is either non-existant or opposite to fixed-wing. Nick evidently agrees with me. In clarifying a previous post where he was talking about the behavior of the "shark fin" attached to the fuselage roof of the Bell 212, he writes:
Phoinix, I wasn't clear enough. It counteracts the roll left with right pedal, which is unstable, and not allowed for IFR flight.
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PPRUNE Fan,
Don't get hung up on the word trim. That word to me means the place where the stick is put to make the helo stay right where you want it. If you are flying at 80 knots, the cyclic is forward of where it is in a hover, and a bit to the right, in most western helos. If you then push full right pedal so the aircraft flips around in yaw and goes backwards at 80 knots, do you think the aircraft will just stay level in pitch and roll? Of course not. Because the cyclic is in the "wrong" place for the new position, it will cause the aircraft to roll and pitch a lot.
For small angles of yaw, this misplaced cyclic will tend to cause positive dihedral. The effect at very low speeds like 60 knots and below, is small, and easily over shadowed by the effects of the fuselage, horizontal tail and even that fin on the roof. That might be why your experiment in your helo shows no positive dihedral. What helo? What speed? In an S76 at 140 knots, yaw is more powerful that lateral cyclic in creating a bank! In an S-76 at 40 knots, it will not bank, just swap ends.
I don't have the time to answer each of your points, but you are basically incorrect if you think that pushing pedal does not cause a turn, if the wings are level. (This is not the basic subject here, as I contend some bank will happen, and you have to supress it with cyclic). If the ball is out and the wings are level, you are turning, that's why the ball is out! I won't go thru a tome here. If you disgree, then tell us why the ball is not centered.
Don't get hung up on the word trim. That word to me means the place where the stick is put to make the helo stay right where you want it. If you are flying at 80 knots, the cyclic is forward of where it is in a hover, and a bit to the right, in most western helos. If you then push full right pedal so the aircraft flips around in yaw and goes backwards at 80 knots, do you think the aircraft will just stay level in pitch and roll? Of course not. Because the cyclic is in the "wrong" place for the new position, it will cause the aircraft to roll and pitch a lot.
For small angles of yaw, this misplaced cyclic will tend to cause positive dihedral. The effect at very low speeds like 60 knots and below, is small, and easily over shadowed by the effects of the fuselage, horizontal tail and even that fin on the roof. That might be why your experiment in your helo shows no positive dihedral. What helo? What speed? In an S76 at 140 knots, yaw is more powerful that lateral cyclic in creating a bank! In an S-76 at 40 knots, it will not bank, just swap ends.
I don't have the time to answer each of your points, but you are basically incorrect if you think that pushing pedal does not cause a turn, if the wings are level. (This is not the basic subject here, as I contend some bank will happen, and you have to supress it with cyclic). If the ball is out and the wings are level, you are turning, that's why the ball is out! I won't go thru a tome here. If you disgree, then tell us why the ball is not centered.
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BHT-212 IFR
Limitations
1-7. AIRSPEED
VMIN (IFR) - 40 KIAS.
NOTE
Due to control authorities
required for flight at airspeeds
below 40 KIAS, AFCS ATTD mode
should not be utilized except for
ground checks.
VNE (IFR or VFR) - 120 KIAS from sea
level up to and including 3000 feet HD at
8800 pounds (3991.6 kilograms) or less
GW decreasing linearly to VNE of 100 KIAS
at 11,200 pounds (5080.3 kilograms) GW, CG of 132.0 to 142.5.
Refer to OPERATING LIMITATIONS decal figure 1-2 V
decreases 3 KIAS per 1000 feet above 3000
feet HD.
VNE (VFR only)(CG 142.5 to 144.0) - 110
KIAS from sea level up to and Including
3000 feet HD at 10,000 pounds (4536
kilograms) or less GW decreasing linearly
to VNE of 100 KIAS at 11,200 pounds
(5080.3 kilograms) GW, CG of 142.5 to 144.0.
Refer to OPERATING LIMITATIONS
decal, figure 1-2.
VNE decreases 3 KIAS
per 1000 feet above 3000 feet H
VNE (VFR only) doors open or removed -
100 KIAS for any GW. Refer to Type of
Operation.
Maximum airspeed when above maximum
continuous torque (87.5%) is 80 KIAS.
Rev.2 1-5
Limitations
1-7. AIRSPEED
VMIN (IFR) - 40 KIAS.
NOTE
Due to control authorities
required for flight at airspeeds
below 40 KIAS, AFCS ATTD mode
should not be utilized except for
ground checks.
VNE (IFR or VFR) - 120 KIAS from sea
level up to and including 3000 feet HD at
8800 pounds (3991.6 kilograms) or less
GW decreasing linearly to VNE of 100 KIAS
at 11,200 pounds (5080.3 kilograms) GW, CG of 132.0 to 142.5.
Refer to OPERATING LIMITATIONS decal figure 1-2 V
decreases 3 KIAS per 1000 feet above 3000
feet HD.
VNE (VFR only)(CG 142.5 to 144.0) - 110
KIAS from sea level up to and Including
3000 feet HD at 10,000 pounds (4536
kilograms) or less GW decreasing linearly
to VNE of 100 KIAS at 11,200 pounds
(5080.3 kilograms) GW, CG of 142.5 to 144.0.
Refer to OPERATING LIMITATIONS
decal, figure 1-2.
VNE decreases 3 KIAS
per 1000 feet above 3000 feet H
VNE (VFR only) doors open or removed -
100 KIAS for any GW. Refer to Type of
Operation.
Maximum airspeed when above maximum
continuous torque (87.5%) is 80 KIAS.
Rev.2 1-5