helicopter main rotor system

Are you looking for the Helicopter Main Rotor System? Read through for types of helicopter main rotor system. You will also find how to make helicopter rotor blades in the post.

A variant of the tandem is the coaxial rotor helicopter ( Figure 3a ) which has the same principle of operation, but the two main rotors are mounted one above the other on coaxial rotor shafts. This constructive solution was developed by Nicolai Ilich Kamov. Another helicopter type is the synchropter, which use intermeshing blades ( Figure 3b ). This type of helicopter was proposed by Charles Kaman.

types of helicopter main rotor system

Helicopter Main Rotor System

Figure 3.The coaxial rotors (a) and the intermeshing blades (b).

If the two rotors are mounted either side of the fuselage, on pylons or wing tips, the configuration is referred to as side by side ( Figure 4 ).

Figure 4.The side by side rotors.

Another aircraft type that should be mentioned is the autogiro (invented by Huan de la Cievra), which is a hybrid between a helicopter and a fixed wing airplane. It uses a propeller for the forward propulsion and has freely spinning nonpowered main rotor that provides lift.

2. Basics of helicopter aerodynamics

The basic flight regimes of helicopter include hover, climb, descent, and forward flight, and the analysis and study of these flight regimes can be approached by the actuator disk theory, where an infinite number of zero thickness blades support the thrust force generated by the rotation of the blades [1]. The air is assumed to be incompressible and the flow remains in the same direction (one-dimensional), which for most flight conditions is appropriate. The helicopter main rotor generates a vertical force in opposition to the helicopter’s weight and a horizontal propulsive force for forward flight. Also, the main and tail rotors generate the forces and moments to control the attitude and position of the helicopter in three-dimensional space.

2.1. Hovering flight

The cross sections in Figure 5 denote: the plane far upstream of the rotor, where in the hovering case the air velocity is null (section 0–0); the planes just above and below the rotor disk (sections 1–1, and 2–2); the far wake section, denoted by ∞. At the plane of rotor, the velocity through the rotor disk is vi (named the induced velocity) and in the far wake the air velocity is w. For a control volume surrounding the rotor and its wake, as shown in Figure 5 and dS→=n→⋅dSdS→=n→⋅dS the unit normal area vector (the unit normal vector n→n→ is oriented outward the control volume), according to the Reynolds Transport Theorem, for any extensive parameter B, where B = b ⋅ m, the following equation is valid(dBdt)system=∂∂t∭controlvolumeρbdV+∬controlsurface(ρb)V→⋅dS→dBdtsystem=∂∂t∭controlvolumeρbdV+∬controlsurfaceρbV→⋅dS→ E1

Figure 5.The helicopter in hovering flight.

where V→V→ is the local velocity, m is the mass of fluid, and ρ is the fluid density. For a steady flow, the above equation becomes(dBdt)system=∬controlsurface(ρb)V→⋅dS→dBdtsystem=∬controlsurfaceρbV→⋅dS→ E2

The conservation of mass (this case corresponds to B = m and b = 1)(dmdt)system=∬controlsurface(ρ)V→⋅dS→dmdtsystem=∬controlsurfaceρV→⋅dS→ E3

This equation requires the condition that the total amount of mass entering a control volume equals the total amount of mass leaving it. For steady-flow processes, we are not interested in the amount m of mass that flows in or out the control volume, but we are interested in amount of mass flowing per unit time, that is the mass flow rate, ṁ ṁ , well the conservation of fluid mass applied to this finite control volume can be rewritten as−∬surface2ρvidS+∬surface∞ρwdS=0−∬surface2ρvidS+∬surface∞ρwdS=0 E4

Therefore,ρviA=ρwA∞ρviA=ρwA∞ E5

The conservation of fluid momentum (this case corresponds to B=mV→B=mV→ and b=V→b=V→ )(dmV→dt)system=∬controlsurface(ρV→)V→⋅dS→dmV→dtsystem=∬controlsurfaceρV→V→⋅dS→ E6

The principle of conservation of fluid momentum gives the relationship between the rotor thrust and the time rate of change of fluid momentum out of the control volume. The left part of Eq. (6) represent the sum of all forces that operate upon the control volume, namely the helicopter rotor thrust force, T. In projection on rotational axis, Eq. (6) becomesT=w∬surface∞(ρw)dS=wṁ T=w∬surface∞ρwdS=wṁ E7

where ṁ ṁ is the mass flow rate in the control volume.

The conservation of energy (in this case B=E=12mV2B=E=12mV2 and b=12V2b=12V2 )(dEdt)sistem=∬controlsurface(ρ12V2)V→⋅dS→dEdtsistem=∬controlsurfaceρ12V2V→⋅dS→ E8

The work done on the helicopter rotor is equal to the gain in energy of the fluid per unit time, and dE/dt represents the power consumed by the rotor, being equal to T ⋅ vi , therefore,T⋅vi=∬controlsurface(ρ12V2)V→⋅dS→=12w2ṁ T⋅vi=∬controlsurfaceρ12V2V→⋅dS→=12w2ṁ E9

Taking into account that T=ṁ wT=ṁw , we have ṁ wvi=12w2ṁ ṁwvi=12w2ṁ or vi=12wvi=12w .

From the equation of continuity ρviA = ρwA , it follows that A∞=12AA∞=12A and obviously, r∞=R2√r∞=R2 therefore, the ratio of the rotor to the radius of the wake is R/r∞=2–√R/r∞=2 .

Replacing the velocity w in the vena contracta (section ∞) in the expression of thrust force T, it follows thatT=ṁ w=ṁ (2vi)=ρAvi(2vi)=2ρAv2iT=ṁw=ṁ2vi=ρAvi2vi=2ρAvi2 E10

The induced velocity at the plane of the rotor disk is vhover ,vh=vi=TA12ρ−−−−√vh=vi=TA12ρ E11

This expression shows that induced velocity is dependent explicitly on the disk loading T/A, which is an important parameter in the helicopter design.

The power required to hover is the product between thrust T and induced velocity vi ,P=T⋅vi=TTA12ρ−−−−√=T322ρA√P=T⋅vi=TTA12ρ=T322ρA E12

This power, called the ideal power, forms the majority of the power consumed in hover, which is itself a high power-consuming helicopter flight regime.

how to make helicopter rotor blades

Top 10 Luxury Helicopters in the World

Most people have heard of personal and charter jets, but luxury helicopters are the genuine gems. Not only are these aircraft comparatively less expensive, but helicopters can approach places that bulky jets can’t. Having a private or commercial helicopter is expedient, more environment friendly, and a symbol of status. Celebrities including Brad Pitt and Angelina Jolie and Donald Trump own a luxury helicopter, and this slot market has grown considerably in recent years due to demand from the rich.

They are well-appointed with all the newest technology, and interior seating marks that are designed in fine Italian leather upholstery.

Therefore the list of top 10 luxury helicopters is given below:

1. Augusta Westland AW119 Ke Koala:

luxury helicopters

The Koala is chiefly used by law enforcement, but it can easily provide accommodation to a group of corporate directors traveling on business. It has a VIP services quite adequately, with premium leather upholstery and seating for about 6 passengers and 2 operators. The Koala reaches a top speed of 166 mph (267 km/h) and a range of 618 miles (995 km). Price ranges from $1.8 to $3 million.

2. Eurocopter Hermès EC 135:

luxury helicopters

Though this brand of luxury helicopters is not suitable for long distant trips, is has a class apart built. The typical EC 135 will cost you a mere $4.2 million, but the one with the interior design from the best in class designer will cost you up to $6 million. The top speed is 178 mph, but the range is just 395 miles.

3. Augusta Westland AW109 Grand Versace VIP:

luxury helicopters

Augusta Westland teamed up with the Italian fashion house Versace to produce a super luxury interior for this fancier version of the AW109. The top speed is about 177 mph and a range of 599 miles. The mere difference is that all 599 of those miles will be more luxurious for the VIP passengers. Hence, will cost you $6.3 million price tag and the helicopter is fully covered in Versace leather, design and exterior.

4. Eurocopter Mercedes-Benz EC 145:

luxury helicopters

If you’re a Mercedes fan, now you can fly your preferred brand helicopter too. A regular EC 145 costs about $5.5 million, so the Mercedes version is going to cost anywhere around $7 million. But it’s totally worth it. No other Mercedes can go 153 mph while flying 17,000 feet above the ground. It has all the luxury of the famous German sports.

5. Eurocopter EC 175:

luxury helicopters

The EC 175 made its wonderful first appearance at the Paris Air Show in 2009. The chief feature of the EC 175 is that it can hold 16 passengers contentedly inside. The top speed reaches 178 mph (286 km/h), with a range of 345 miles (555 km). It costs whooping $7.9 million.

6. Eurocopter EC 155:

luxury helicopters

This is a luxurious chopper. Its top speed is an impressive 200 mph with a range of 533 miles. It can seat as many as 13 passengers; this spacious EC 155 aircraft will cost you $10 million.

7. Sikorsky S-76C:

luxury helicopters

The Sikorsky S-76C is more generally known as Black Hawk. The massive interior is large sufficient to fit up to a dozen passengers, but the seating occupies 4 passengers in Black Hawk model. It reaches a top speed of 178 mph (286 km/h) and has a range of 473 miles (761 km). It would cost you a $12.95 million.

8. Augusta Westland AW139:

luxury helicopters

The AW139 is appropriate for law enforcement, armed patrol and firefighters. It has a capacity to seat 8 passengers. The AW139 can reach an unbelievable top speed of 193 mph (310 km/h), with a range of 573 miles (922 km). It carries a beautiful interior costing you a hefty $14.5 million.

9. Bell 525 Relentless:

luxury helicopters

Like the Gulfstream 650 jet, the Bell 525 Relentless helicopter isn’t on the market currently. This chopper is going to cost $15 million. They predicted that the seating will be for 16, a top speed of 162 mph, and a range of 460 miles. This bright yellow Relentless with amazing seating will cost you a fortune.

10. Sikorsky S-92 VIP Configuration:

luxury helicopters

The S-92 can safely accommodate 9 passengers in its extensive interior cabin. The prices vary exponentially if you plan on decking the interiors with gold or crystal. The top speed of the S-92 is around 194 mph (312 km/h), with a range of 594 miles (956 km). The prices range from $17 million to $32 million.
Helicopter charter can be the most stress-free travel familiarity you will ever have. Which includes being able to travel outside of airports to reach vital meetings or even other flights in a different airport. Though rich class can afford these luxury helicopters, they are worth the investment.

Leave a Comment