Talk:Helicopter

Experimental helicopter by Dr. Boothezaat in 1923

I'm reading through old Time Magazine issues. The March 1923 issue discusses Thomas Edison sending Dr. Boothezaat a congratulations for a test of a helicopter by remaining in the air for 2 min 45 sec at a height of 15 feet. Also see https://time.com/vault/issue/1923-03-03/page/23/. — Preceding unsigned comment added by Noloader (talk • contribs)

New section on transmission design

I noticed that the article does not contain any information on transmission design, which is an important topic for helicopters, so I drafted the following. Since helicopter designs vary so widely, I used words like "usually", "often", and "typically" so it would be clear that not all helicopters share a single design. Please reply with any comments or suggestions. (Note that there is already a subsection within "Saftey" section that discusses transmission safety, see Helicopter#Transmission, but it does not discuss transmission design). Noleander (talk) 15:14, 8 December 2024 (UTC)

Proposed new subsection "Transmission"

The transmission is a mechanical system that transmits power from the engine(s) to the rotors. The transmission is a system of gears, bearings, clutches and shafts that performs several functions (1) Translates the alignment of the drive shaft to match the alignment of the rotor shafts; (2) Reduces the RPM of the drive shaft to the lower RPMs of the rotors; and (3) Enables the engine to engage or disengage from the rotors. For helicopters with tail rotors, the transmission drivetrain forks into two paths: one leading to the main rotor, and one leading to the tail rotor.

The drive shafts of helicopter engines are typically not aligned with the rotor shafts, so the transmission must translate the alignment of the drive shaft to match the shafts of the rotors. Many engine drive shafts are aligned horizontally, yet the main rotor shaft ("mast") is usually vertical, and the tail rotor shaft is often perpendicular to the engine's drive shaft. The transmission contains a series of gears, usually bevel gears, that translate the alignment of the drive shaft to the alignment of the rotor shafts.

The transmission also reduces the RPMs of the engine to the lower RPMs required by the rotors. The output drive shaft of the engine, before any gearing is applied, is typically between 3,000 and 50,000 RPM (turbine engines typically have higher RPM than piston engines). The main rotor typically rotates between 300 to 600 RPM. The tail rotor, if present, usually rotates between 1,000 to 5,000 RPM. (The RPMs of a given model of helicopter are usually fixed — the RPM ranges listed above represent a variety of helicopter models). The transmission contains a series of reduction gears to reduce the engine RPM to the rotor RPMs. Several types of reduction gears may be used, including bevel gears, planetary gears, helical gears, and spur gears. Most transmissions contain several reduction gears: the engine itself may contain reduction gears (often spur gears) between the engine's internal shaft and the output drive shaft; the main rotor may have a reduction gear at its base (typically a planetary gear); and there may be reduction gears at the tail rotor, and on the shaft leading to the tail rotor.

The transmission often includes a clutch, which permits the rotors to engage or disengage from the engine. A clutch is required so the engine can start up and gain speed before taking the load of the rotors. The clutch is also required in the case of engine failure: in that situation, the rotors must disengage from the engine so that the rotors can continue spinning and perform autorotation. Helicopter clutches are usually freewheel clutches relying on centrifugal forces (sprag clutchs are commonly used), but belt drive clutches are also used. Noleander (talk) 15:14, 8 December 2024 (UTC)

This seems very relevant and not an issue to me. You need to pipe a more specific link for transmission in the first sentence, since that is a disambiguation page and not that useful of a link. Regards -Fnlayson (talk) 03:52, 9 December 2024 (UTC)

Thanks for the feedback, I made that change. Noleander (talk) 05:05, 9 December 2024 (UTC)

References

Eastern bias

How did I guess on turning to the History section that yes, the helicopter was in fact an Eastern invention and Europeans just stole the idea from them. 86.12.51.29 (talk) 11:04, 25 May 2025 (UTC)

Semi-protected edit request on 1 December 2025

Change the Hazards section to read:

As with any moving vehicle, unsafe operation could result in loss of control, structural damage, or loss of life. The following is a list of some of the potential hazards for helicopters:

• Vortex ring state is a condition encountered when a rotor system catches up with and disrupts its own wake, changing it from a coherent state into a disordered, turbulent state. For a main rotor system, this hazard is induced by a combination of low airspeed, high power setting, and high descent rate. This has alternatively been referred to as "Power Settling" primarily by the U.S. Navy, and "Settling with Power" by the U.S. Army and subsequently the FAA.
• Retreating blade stall is experienced during high speed flight and is the most common limiting factor of a helicopter's forward speed.
• Ground resonance is a self-reinforcing vibration that occurs when the lead/lag spacing of the blades of an articulated rotor system becomes irregular, causing the center of gravity for the rotor system to become misaligned with its center of rotation.
• Low-G condition is an abrupt change from a positive G-force state to a negative G-force state that results in an unloaded disc and excessive flapping. If excessive cyclic is applied while the disc is unloaded, the main rotor could strike the tail causing catastrophic failure.
• Dynamic rollover occurs when a pivot point is introduced (most often a stuck skid/wheel) and main rotor lift becomes a moment, which rolls the helicopter over rapidly. This is most common when picking up to a hover from an austere landing site and a skid has become stuck, such as in mud or ice, or under a rock, log, or other obstruction.
• Powertrain failures, especially those that occur within the shaded area of the height–velocity diagram.
• Tail rotor (anti-torque system) failures which occur from either a mechanical malfunction of the tail rotor control system, or an aerodynamic loss of tail rotor thrust authority, called "loss of tail-rotor effectiveness" (LTE).
• Brownout in dusty conditions or whiteout in snowy conditions.
• Low rotor RPM, sometimes referred to as Overpitching , occurs if collective pitch is increased--with corresponding increase in the pitch and drag of the rotor blades--when adequate engine power is not available to drive the rotor system at sufficient RPM. The subsequent loss of rotor RPM results in a loss of lift from the main rotor(s), and can also lead to a loss of thrust from the tail rotor (or anti-torque system).
• Rotor overspeed, which can over-stress the rotor hub pitch bearings (brinelling) and, if severe enough, cause blade separation from the aircraft.
• Wire and tree strikes due to low altitude operations and take-offs and landings in remote locations.
• Controlled flight into terrain in which the aircraft is flown into the ground unintentionally due to a lack of situational awareness.
• Mast bumping in some helicopters

The primary change to this entry is the description of Vortex Ring State. Changes are supported on pages 10-11 of the cited source, as well as many others including Heyson (1980), Wagtendonk (1992), the Helicopter Pilot Manual (1998), Varnes et al (1998), FAA-H-2023-21 (2001, 2012, 2019), Leishman (2002), Ahlin and Brown (2005), Prouty (2009), and Mullen and Bernini (2016). All other changes are supported by FAA-H-2023-21. Cptjbcv (talk) 20:38, 1 December 2025 (UTC)

 Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. NotJamestack (✉️|📝) 21:18, 1 December 2025 (UTC)

Was AI used in creating any of this content? cheers. anastrophe, an editor he is. 23:35, 1 December 2025 (UTC)