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Aviation: Rotorcraft

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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)

Semi-protected edit request on 5 February 2024

I want to edit something because it doesn’t seem right and giving wrong information about helicopters. You should have also all the answer to helicopters

}} 86.49.255.40 (talk) 12:32, 5 February 2024 (UTC)[reply]

Semi-protected edit request on 12 June 2024

This edit request has been answered. Set the |answered= or |ans= parameter to no to reactivate your request.

The following phrase, whilst partially correct, is misleading:

"

Most helicopters have a single main rotor, but torque created by its aerodynamic drag must be countered by an opposed torque"

[Suggested Correction]: Aerodynamic drag affects the entire aircraft. Specifically, the aerodynamic drag experienced by the rotor blades is transmitted to the airframe by an equal and opposite 'reaction torque' via the rotor drive shaft and hence the engine mounts. Unlike an automobile engine, in which the. car body cannot rotate in response to this torque, a helicopter is free to rotate around the rotor drive shaft axis. A tail rotor, 'anti-torque rotor', is therefore necessary to establish a balancing (anti-)torque to prevent the airframe from spinning around the rotor axis.

Suggest the text is amended accordingly. 86.26.142.91 (talk) 10:49, 12 June 2024 (UTC)[reply]

Not done: please provide reliable sources that support the change you want to be made. Lightoil (talk) 15:28, 12 June 2024 (UTC)[reply]

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. I drafted the following. I tried to word it so that it was generic ... so 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. Noleander (talk) 15:14, 8 December 2024 (UTC)[reply]

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, clutches, shafts, and other mechanisms. The transmission 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) Supports situations where the engine engages or disengages from the rotors (such as engine start-up, or autorotation after engine failure). For helicopters with tail rotors, the transmission gear chain forks into two paths: one leading to the main rotor, and one leading to the tail rotor.^[1]^[2]^[3]

The transmission must translate the alignment of the drive shaft to match the shafts of the rotors. The drive shafts of helicopter engines are typically not in the same alignment as the rotor shafts. 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.^[4]

The transmission also reduces the RPMs of the engine to the lower RPMs required by the rotors. The 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 the engine and rotors is essentially fixed for a given model of helicopter; the ranges cited above span most models).^[5] 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) at the output end, where the drive shaft emerges; 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 support autorotation. Helicopter clutches are usually freewheel clutches relying on centrifugal forces - most commonly, a sprag clutch is used, but belt drive clutches are also used. Noleander (talk) 15:14, 8 December 2024 (UTC)[reply]

^ Helicopter Flying Handbook, FAA, 2024, Chaper 4 "Helicopter Components, Sections, and Systems" https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook
^ Helicopter Instructor's Handbook, FAA, 2014, ISBN 9781629141442, 1629141445
^ Helicopter Pilot's Manual, Norman Bailey, 2014, Crowood, ISBN 9781847979230, 1847979238
^ Bevel Gear Fundamentals and Applications, Jan Klingelnberg, 2015, Springer Berlin Heidelberg, ISBN 9783662438930, 3662438933
^ Seddon, John; Newman, Simon (2011). Basic Helicopter Aerodynamics. John Wiley and Sons. p. 216. ISBN 978-1-119-99410-7. The rotor is best served by rotating at a constant rotor speed

[1] Helicopter Flying Handbook, FAA, 2024, Chaper 4 "Helicopter Components, Sections, and Systems" https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook

[2] Helicopter Instructor's Handbook, FAA, 2014, ISBN 9781629141442, 1629141445

[3] Helicopter Pilot's Manual, Norman Bailey, 2014, Crowood, ISBN 9781847979230, 1847979238

[4] Bevel Gear Fundamentals and Applications, Jan Klingelnberg, 2015, Springer Berlin Heidelberg, ISBN 9783662438930, 3662438933

[newman-5] Seddon, John; Newman, Simon (2011). Basic Helicopter Aerodynamics. John Wiley and Sons. p. 216. ISBN 978-1-119-99410-7. The rotor is best served by rotating at a constant rotor speed

[1]

[2]

[3]

[4]

[5]

@@ Line 46: / Line 46: @@
 The [[transmission]] is a mechanical system that transmits power from the engine(s) to the rotors.  The transmission is a system of [[gears]], [[clutch]]es, [[shafts]], and other mechanisms.  The transmission 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) Supports situations where the engine engages or disengages from the rotors (such as  engine start-up, or [[autorotation]] after engine failure).  For helicopters with tail rotors, the transmission gear chain forks into two paths: one leading to the main rotor, and one leading to the tail rotor.<ref>''Helicopter Flying Handbook'', FAA, 2024, Chaper 4 "Helicopter Components, Sections, and Systems"  https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook</ref><ref>''Helicopter Instructor's Handbook'', FAA, 2014, ISBN 9781629141442, 1629141445</ref><ref>''Helicopter Pilot's Manual'', Norman Bailey, 2014, Crowood,  ISBN 9781847979230, 1847979238</ref>
-The transmission must translate the alignment of the drive shaft to match the shafts of the rotors.   The drive shafts of helicopter engines are typically not in the same alignment as the rotor shafts.  Many engine drive shafts are aligned horizontally, yet the main rotor shaft 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 gear]]s, that translate the alignment of the drive shaft to the alignment of the rotor shafts.<ref>''Bevel Gear Fundamentals and Applications'', Jan Klingelnberg, 2015, Springer Berlin Heidelberg, ISBN 9783662438930, 3662438933</ref>
+The transmission must translate the alignment of the drive shaft to match the shafts of the rotors.   The drive shafts of helicopter engines are typically not in the same alignment as the rotor shafts.  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 gear]]s, that translate the alignment of the drive shaft to the alignment of the rotor shafts.<ref>''Bevel Gear Fundamentals and Applications'', Jan Klingelnberg, 2015, Springer Berlin Heidelberg, ISBN 9783662438930, 3662438933</ref>
 The transmission also reduces the RPMs of the engine to the lower RPMs required by the rotors.   The drive shaft of the engine, before any gearing is applied, is typically between 3,000 and 50,000 RPM ([[turbine engine]]s typically have higher RPM than [[piston engine]]s).  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 the engine and rotors is essentially fixed for a given model of helicopter; the ranges cited above span most models).<ref name=newman>{{cite book|first1=John|last1=Seddon|first2=Simon|last2=Newman|title=Basic Helicopter Aerodynamics|page=216|publisher=John Wiley and Sons|date=2011|isbn=978-1-119-99410-7|quote=The rotor is best served by rotating at a constant rotor speed}}</ref>     The transmission contains a series of [[reduction gear]]s to reduce the engine RPM to the rotor RPMs.  Several types of reduction gears may be used, including bevel gears, [[planetary gear]]s,  [[helical gear]]s, and [[spur gear]]s.     Most transmissions contain several reduction gears: the engine itself may contain reduction gears (often spur gears) at the output end, where the drive shaft emerges; 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.