Item 0385

OTHER: Helicopter - Outside - Single (2-seat) - Robinson R-22

Locations of specific Information:

This Web Site:

 

SynchroLite ~ DESIGN: Instrument

DESIGN: Control - Flight - Governor

0584

 

DESIGN: Rotor - Hub - Robinson R-22

UniCopter ~ Weight & Balance

UniCopter ~ DESIGN: Instrument

 

Information on Blade Attachment

SynchroLite ~ Weight & Balance

0752

 

0843

MAKE: Control - Flight - Cyclic

0786

 

OTHER - Helicopters

OTHER: Misc. - Safety

0717

 

MAKE: Power Train

DESIGN: Control - Flight - Swashplate

0358

 

MAKE: Engine

OTHER: Aerodynamic - General

0799

 

Control - Flight -Governor

DESIGN: Control - Flight - Cyclic

DESIGN: Rotor - Disk - Cross Coupling

 

UniCopter_Stability

DESIGN: Rotor - Blade - Composite

DESIGN: Rotor - Disk - Undersling

 

Engine - Turbine

DESIGN: Control - Flight - Collective

DESIGN: ~ Engine - Reciprocating - Lycombing - General Information

Other Web Sites:

Picture of Robinson's R-22 Hub

NTSB ~ Robinson Helicopter Company R22 Loss of Main Rotor Control Accidents, National Transportation Safety Board report PB96-91703, NTSB/SIR 96/03 Have PDF file

Spreadsheet for Calculations of R-22 Weight & Balance

Information on the R-22, (plus others)

Robinson Helicopter Company

Robinson page from U.K.

Flight Manual

The Helicopter Aviation Home Page

 Miscellaneous Information:

Center of blade's mass is 42" from the root and the blade weighs 50 lbs. I think that the center of mass is too far from the root.

Prouty's main book shows the R-22 rotor as having an polar moment of inertia of 86.3 slug ft2.

It has been suggested that one of the reasons for the incorporation of the 2 flapping hinges is the large change in the coning angle between depending on whether the craft is carrying one or two people. [~ from D.K.]

It would appear that the use of 2/3 hinges and delta-3 may have been taken from the Weir W-6. ~ [Source ~ MDD p.248]

Rotor Inertia:

From article 'Designing Rotor Blades' by Martin Hollmann in Dec 2001 ~ Jan 2002 issue of Rotorcraft.

"Another not often known secret in rotor blade design is to incorporate a small amount of tip weight into the blades. In the Sportster blades I use a 2.6 lb steel rod. This tip weight does wonders.

It reduces the coning angle, which increases the performance of a helicopter or gyro.

It increases the inertia of the rotor for better autorotation. The early Robinson R22 helicopter did not have tip weights and pilots complained about poor autorotation (2 seconds to put down the collective for autorotation when the engine stopped) and high control sensitivity. I met Frank Robinson one day and told him about rotor tip weights and asked him why he did not use them on his little helicopter. He said that he simply did not think of it. Two weeks later a bulletin from the Robinson Helicopter Co. came out announcing that all R22 blades would be retrofitted with tip weights."

Portion of article on AVweb.
For complete article see:
http://www.avweb.com/articles/rotorrpm.html

"Helicopters with low-inertia rotor systems are extremely unforgiving of low-rotor rpm. Actually, all rotor systems are unforgiving of low rpm, but a low-inertia system loses rpm faster, which requires the pilot to react quicker to prevent low-rotor rpm from reaching the critical stage.

At this point, many helicopter pilots ask "why not just add some blade tip weights to, say, a Robinson R22 helicopter, to make it into a high-inertia system?"

"It's not as easy as that," says Frank Robinson, the R22's designer. "Rotor blade tip speeds are similar for all helicopters regardless of the size of the machine, because they are all limited by the speed of sound in air. The stored energy of a tip weight is only dependent on tip speed, therefore, a one-pound tip weight added to the 50-foot diameter rotor of a large helicopter would store the same energy as a one-pound tip weight added to the 25-foot diameter R22 rotor. However, the centrifugal force produced by a tip weight is inversely proportional to the rotor diameter, so the one-pound tip weight would produce twice as much centrifugal force in the R22 rotor as it would in the larger helicopter rotor, even though it would not store any more energy. The increased centrifugal loads carried by the blades, the pitch change bearings, and by the rotor hub would all be twice as great. Clearly it is very difficult to engineer a small helicopter with a high-inertia rotor." "

Lu Zuckerman's Concerns about the Robinson

Patents Held:

 

4,449,703

Apparatus for bonding main rotor blades

 

4,223,429

Process for bonding main rotor blades from parts having different coefficients of thermal expansion

 

4,131,391

Rotor hub and oil seal ~ Have hard copy.

 

4,114,843

Control stick assembly

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Last Revised: May 22, 2008