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S-46/VS-300/VS-300A   Helicopter

 VS 300-1

VS-300A NX 28996 in Forward flight with Igor Sikorsky at the controls

Background

 

Igor Sikorsky dreamed of building a helicopter from his youth.  In 1931, he applied for a patent for a single main rotor helicopter which included nearly every feature that would be incorporated in the VS-300.  By 1938, technology had caught up with his dream.  When he was summoned to United Aircraft Headquarters in Hartford, Connecticut to be told that the Sikorsky Division which at that time was building fixed-wing aircraft was being shut down due to a lack of business, he requested that he be allowed to keep his design team together to design a helicopter.  His request was granted along with an initial $30,000 budget.  The VS-300 was America’s first practical helicopter.  It was also the first successful helicopter in the world with a single main rotor and a torque compensating tail rotor

 

VS 300-2 
Sketch of a single main rotor helicopter submitted for a Patent in1931which was granted in 1935.

 

 Some preliminary helicopter design work had already been done by Igor Sikorsky, who was the Engineering Manager, and his associates “off the clock” and they were ready to start work.  The basic VS-300 helicopter looked very similar to the 1930 design.

The VS-300 was designed in the spring of 1939 and built that summer.

 

VS 300-3

VS-300 under construction September 8, 1939

 

 

The first flight version of the VS-300 included a 28 foot diameter main rotor and a 75 hp Lycoming engine.  A 40” single blade tail rotor and rigid 4 wheel landing gear with a full swiveling nose and tail wheels were installed. The VS-300 featured full cyclic main rotor control (pitch and roll) and a single pedal tail rotor control (yaw). Vertical control was provided by a large wheel to the right of the pilot.  The first flight on September 14, 1939 by Igor Sikorsky lasted approximately 10 seconds to a height of a few inches.  The helicopter was tethered to a heavy plate by four cables which allowed the helicopter to move in all directions by dragging the plate.  A ground crew was always present to stabilize the helicopter if the pilot lost control to prevent a roll over.  No helicopter flight training was available, so Igor Sikorsky got “On the Job” training learning with each additional flight.  The design team was not familiar with the fact that a spinning rotor had gyroscopic properties (precession) which required an input 90 degrees in rotation before it became effective.  The VS-300 therefore rolled left when the cyclic stick was pushed forward. The initial pilots, Igor Sikorsky and Serge Gluhareff, had no idea whether the control problems were caused by the helicopter design or pilot technique.

 

VS 300-4

The VS-300 in a stable hover on November 24, 1939

 

Changes to the helicopter were made after every flying day by the Night Crew. Obvious changes since the first flight in the above photo are outrigger main landing gear with full swiveling wheels, the tail wheel moved aft, and dampers have been added to the flapping hinge on the main rotor

Flight of the VS-300 continued with each flight a little longer than the last as the pilots adjusted to this unruly machine until December 9, 1939 when a gust of wind tipped over the VS-300 grinding the rotors into the ground and causing major damage to the VS-300.  This ended the career of the First Configuration.

 

The link below, with a commentary in German, shows rare footage of the earliest VS-300 flights.

https://www.youtube.com/watch?v=Ux8dBNX-rGM

 

The VS-300 was completely redesigned and rebuilt.  A decision was made to abandon cyclic control of the main rotor and adapt a design suggested by I.A. Sikorsky, a draftsman and mathematician, and Michael Buivid, the Chief Engineer, which locked out cyclic control and replace it with two additional horizontal tail rotors. Collective pitch control for vertical control was left on the main rotor.  Prior to flight testing of the second configuration, the helicopter was mounted on a pedestal and operated without the main rotor blades installed.  This allowed fine tuning of the new control system and allowed the pilots to become comfortable with the new system before actual flight.

 


AS 300-5

An early version of the VS-300 second configuration

 

VS-300 Development Timeline

 

 
  • Late 1938:  United Aircraft approved development of a research helicopter
 
 
  • March 12, 1939:  Proposal submitted to United Aircraft to design, construct, and demonstrate a single rotor helicopter with an estimated cost of $60,000.
 
 
  •  September 14, 1939: First flight.
 

 

 

VS 300-6

VS-300 First Flight September 14, 1939

 

 
  • December 9, 1939:  VS-300 severely damaged in a rollover accident.  Helicopter rebuilt with 2 horizontal 40” single blade tail rotors to provided pitch and roll control. Only vertical flight was controlled by main rotor (second configuration)
 
 
  • March 6, 1940: First flight of second configuration.
 
 
  • May 13, 1940:  First flight out of the yard
 
 
  • May 20, 1940:  First public demonstration of the VS-300
 
 
  • July 1940: 90 hp Franklin engine installed to increase power.
 
 
  • April 15, 1941:  U.S.National Endurance Record Set (1 hour, 5 minutes, 14.5 seconds)
 
 
  • April 17, 1941:  First helicopter water landings.
 

 

 

VS 300-7

VS-300 second configuration with heavy duty outriggers

 

  May 6, 1941:  Igor Sikorsky establishes an International Helicopter Endurance Record of 1 hour, 32 minutes, and 26 seconds with the VS-300  

 

 

VS 300 -8

Igor Sikorsky after setting endurance record with VS-300 Second Configuration

 

The link below is to a Paramount Newsreel “He Sits on Air” which includes footage of the endurance record.

http://www.youtube.com/watch?v=1ULvnlGpYfw

 

 
  • June 11, 1941:  Major alterations completed.  Redesignated as the VS-300A.  A single vertical tail with a horizontal rotor mounted on it for longitudinal (pitch) control replaced the 2 horizontal tail rotors on outriggers.  Lateral control (roll) was controlled by cyclic pitch to the main rotor through a swashplate. Both the lifting tail rotor and the anti-torque tail rotor were a 46” two blade design. (third configuration).
 

 

 

VS 300-9

Les Morris hovers the VS-300A Third Configuration with “Bob Sled” nose.

 

 
  • December 8, 1941:  VS-300A. First flight of the fourth and final configuration.  The single horizontal tail rotor was removed and full cyclic pitch control was restored.  A 30 foot diameter main rotor was installed.
 
 
  • December 31, 1941: Hydraulic dampers added to control the lead-lag of main rotor blades. This solved a serious vibration problem.  This was the final major change which allowed flight at speeds of 80 mph.  The helicopter had become a pleasure to fly.
 

 

The link below is to a promotional film from 1943 of Sikorsky Test Pilot Les Morris flying the VS-300A and a helicopter status report by Igor Sikorsky.

 

http://www.youtube.com/watch?v=SEAy2Yx_dY4

 

 
  • October 7, 1943:  Last flight. The VS-300A was presented to Henry Ford at the Edison Museum in Dearborn Michigan.  Total flight time: 102 hours, 34 minutes, and 51 seconds.
 

 

VS 300 -10

Igor Sikorsky flies the VS-300A for the last time October 7, 1943

 

VS 300-11

Igor Sikorsky in cockpit of VS-300A at completion of last flight

 

The link below is a short newsreel of the Sikorsky VS-300A Helicopter at the Henry Ford (Edison) Museum (1943)
http://www.youtube.com/watch?v=LmQ0Hu98Y-k

 

VS 300-12

A Souvenir Postcard carried on last VS-300A flight

 

 

Configuration Features

 

Synopsis of VS-300 Configurations

 

 

 

  September 1939 First Flight Configuration Canted Main Struts  
VS 300-13
   
   
  • 4 Wheel Landing Gear with non-swiveling Mains.
   
  • Full Cyclic Pitch Control
   
  • Single Tail Rotor Pedal
   
  • Short Main Rotor Shaft
   
  • Monocoque Sheet Metal Box Style Tail Boom
   
  • Vertical Tail Fin
   
  • Single Blade Tail Rotor
   
  • Collective Wheel on right side
     
 

 

November 1939 Configuration (Modified 1st Configuration)

  • Full Swiveling Vertical Main Landing with Gear Oleo Struts
  •  T-bar Horizon Reference
  • Dampers in Flapping Hinge
  • Collective Pitch Stick on left side
  • Dual Tail Rotor Pedals
VS 300-14
   
 
 
 
 
 
 
 
 
 
 

 

March 1940 Configuration (2nd Configuration)

  • Cyclic control removed from Main Rotor
  • Collective control remained
  • 2 horizontal rotors mounted on flat outriggers for pitch and roll control
  • Canted Mail Landing Gear from original design reinstalled
  • Tail skids replaced nose and tail wheels
  • Tubular rear fuselage added for strength and ease of modification
VS 300-15
   
 

 

August 1940 Configuration (Strengthened 2nd Configuration)

  • Outriggers strengthened with tubular structure.
  • 2 blades used on all three tail rotors
VS 300-16
   
 

 

April 1941 Amphibious  2nd Configuration

  • Short Rubber Main Floats
  • Tail Float
  • Basketball Nose Bumper
VS 300 -17
   
 

 

August 1941 Configuration (3rd Configuration)

  • Single horizontal tail rotor for pitch control
  • Lateral Azimuthal Control restored to main rotor
  • Longer Main Rotor Shaft

VS 300-18
   
 

 

December 1941 Configuration (4th Configuration)

  • Round Fabric nose and single sheet of fabric on rear fuselage
  • Full Azimuthal control (Lateral and Pitch restored to main rotor
  • Hydraulic Dampers on lead-lag of  main rotor blades
VS 300-19
   
 
   

 

VS-300 Helicopter Design

The VS-300 was designed as a research vehicle which was easily modified based on test results.  Although the VS-300 is described as having four configurations it was in fact modified every night after a test flight. A ”Lessons Learned” meeting was held by the design team after each flight and decisions were made on what to try next.  By the end of the VS-300 development program only the pilot seat, 2 main landing gear wheels, main transmission box, central fuselage framework, and gas tank remained from the original VS-300.  The picture below shows the VS-300 on the day of the first flight.  Visible in this picture is the single tail rotor pedal and the Collective control wheel, similar to the trim controls on the flying boats, on the right side of the helicopter.  The cables from the top of the main rotor to the blades prevented the blades from drooping too much when the blades were not turning.

 

VS 300 -20

VS-300 on the day of the first flight, September 14, 1939

 

The picture below dated November 13, 1939 shows a much modified main landing gear with swiveling wheels, dual tail rotor pedals, dampers on the main rotor flapping hinge, and a “T” bar to provide a horizon reference are noticeable changes from the first flight configuration.

 

 

VS 300 -21
VS-300 in hangar on November 13, 1939

 

Cyclic control for a helicopter was an unknown area in 1939.  Juan de la Cierva had attempted to use it on the Autogiro but abandoned it after an unexplained accident. After a VS-300 accident in December 1939, cyclic control was abandoned by the Sikorsky design team.  It was not returned until the Summer of 1941, when lateral control was returned to the main rotor in the 3rd configuration.  The gyroscopic qualities of a spinning rotor were still not understood and acceptable control was obtained by experimentation rather the mathematical calculations.  Control inputs to the stationary swashplate were incrementally moved until moving the cyclic stick left rolled the helicopter left.  Once lateral control was satisfactory, the 4th configuration was constructed returning full Azimuthal control (pitch and roll control) with the first flight on December 8, 1941.  Flights with this configuration encountered a “Wobble” when accelerating.  This issue was resolved on December 31, 1941when Igor directed the crew to reinstall dampers, previously used to control blade flapping, in a horizontal position to dampen lead and lag blade movement.  This was the “Silver Bullet” and resulted in a smooth flying machine.  As a historical note, the XR-4 helicopter with full Azimuthal flight controls made its First Flight on January 14, 1942, two weeks after control problems were solved on the VS-300A.

 

Engine

Power was supplied by a 75 hp (at 3200 rpm) Lycoming O-145-C3 air-cooled four cylinder horizontally opposed engine.  The engine was installed with the propeller shaft pointed aft and connected to the main gear box by a series of six V-belts. Tension on the belts was provided by engaging an idler pulley.  In July, 1940 the engine was replaced with a 90 hp (at 2,500 rpm) Franklin 4AC-199-E air cooled four cylinder horizontally opposed engine to provide additional power. In April, 1941 an upgraded 4AC-199 engine with 90 hp at 2680 rpm and 100 hp at 3050 rpm was installed.

 

 

VS 300 -22

Franklin 90 hp model 4AC-199-E (O-200-1) engine

 

Cooling Fan

 

The engine was cooled by a “squirrel cage“, V-belt driven, cooling fan in a sheet metal enclosure mounted above the engine which forced cooling air down across the cylinder cooling fins.

 

Starter and Battery

 

In order to save weight the battery was removed from the VS-300 after the first flight.  Then the starter was also removed. A handle was installed on the starter and it was held in place to start the engine and then removed.  Later the engine was started by a rotary shaft attached to the lower pulley on the engine.  After engine start, the rotor was spun-up by hand and then the idler pulley was engaged to tension the 6 drive belts. A bungee cord maintained tension on the idler pulley.

 

 
VS 300 -23Battery Cart alongside VS-300 

 

 

 

 

 

 

 

 

  VS 300 -24

  Late model Start Cart with start adapter

 

 

        

 Landing Gear

The original landing gear consisted of 2 main landing gear with diagonal struts and swiveling front and rear wheels.  This was soon replaced by vertical oleo struts with swiveling wheels on the main landing gear and a nose wheel.  As development progressed diagonal main landing gear was reinstalled and eventually the nose and tail wheel were removed with only a tail skid remaining on the final version.

 

Fuselage

The original forward fuselage structure framework was constructed almost entirely of 4130 chrome-molybdenum steel thin wall tubing with the aft fuselage an aluminum box structure.  In the second configuration the aft structure.was changed to steel thin wall tubing for strength and easy modification.

 

VS 300 -25

VS-300A Main Rotor Head

 

Drivetrain

A Dural Pulley was attached to the propeller shaft on the Franklin 90 hp engine which was connected to a larger  Dural Pulley by 6 V-belts (Gates Vulcco Ropes) for the first rpm reduction of 1.76:1. Shafting from the upper pulley went forward to the main gearbox which contained spiral bevel gears from the rear end (differential) of a Mack truck.  This was the second rpm reduction of 5.9:1 to obtain the correct main rotor rpm.  A rear shaft ran aft and powered the anti-torque tail rotor and the horizontal rotors on earlier versions by V-belt drive.  The upper pulley also contained a free-wheeling unit to allow autorotation in the event of engine failure (No autorotations were attempted with the VS-300).

 

VS 300 -26

NOTE: RPMs Presented are Nominal for Illustration Purposes.

VS-300 Second Configuration Drive Train Schematic

 

The Gates Vulco Ropes identified in the illustration were a Gates proprietary design V-belt with concave sides.  When the belt was under tension the torque flattened the belt for full contact with the pulley.

 

Main Rotor Blades

The main rotor blade had a spruce wooden spar extending from root to tip.  The leading edge consisted of lamination of spruce, balsa, and mahogany.  A high speed (since rotor tip speeds are over 254 mph (374 ft./sec) symmetrical NACA 0012 airfoil was used.  This airfoil had a stable center of pressure and the feathering axis and chordwise center of gravity were collocated making it ideal for a rotating wing.

 

 

 

VS 300 -27

VS-300 Main Rotor Blade before covering – First Flight design

VS 300-29

Later design with wire trailing edge

 

 

Tail Rotor Blades

The tail rotor blades were all wood. The spar was made of maple, with poplar ribs and birch veneer pockets

 

VS 300 -29

VS-300A Tail Rotor Blades

 

VS-300 Flight Simulator

In 1938 Michael Buivid and Bob Labensky designed and fabricated the first helicopter simulator.  The configuration of the simulator changed daily and proved to be a valuable tool in predicting pilot’s ergonomic requirements and reactions to tilting fore and aft and laterally, and rotation for directional control.

 

VS 300 -30

Michael Buivid, Igor Sikorsky, Bob Labensky, and Michael Gluharefff with the VS-300 Simulator

 

Rotor Blade Test Unit

The rotor blade test rig was built to measure the lift and torque required to drive various blade designs.

 

VS 300 -31

1939 Single Blade Rotor Lift and Torque Test Rig

 

 

General Arrangement Drawing

 

vs-300 -3x

VS-300A 3-view Drawing

 

Mission Systems

 

Cargo Carriers

The VS-300 utilized a wicker basket to carry various items to demonstrate the controllability of the helicopter.

On the VS-300A a converted metal bicycle basket replaced the wicker basket.

 

 

VS 300 -33
VS-300 Wicker Basket Cargo Carrier 

VS 300 -34
  VS-300A Metal Wire Basket
 

                                           
                      

Amphibious Floats

The VS-300 was originally equipped with 2 Hot Dog floats, a tail float, and a basketball for a nose bumper. 

 

VS 300 -35

VS-300 with short pneumatic rubber floats

 

Further along in the program the VS-300A was equipped with longer Hot Dog floats which eliminated the need for the tail float and nose bumper.

 

VS 300 -36

VS-300A with long floats picking up a suitcase

 

 

 

 

General Characteristics and Performance VS-300A

 

PERFORMANCE

Standard Day, Sea Level

Maximum speed (Vne)

60 mph  52.1 kts   96.6 km/hr

Cruise speed

35 mph  30.4 kts   56.3 km/hr

Range

53  miles                    85.3km

Service ceiling

100 ft                        30.48 m

 

WEIGHTS

 

Maximum takeoff gross weight

1,325 lbs        601 kg

Weight empty

1,041 lbs   472.19 kg

Maximum fuel load

14.7 gal       55.65 ltr

 

GENERAL DATA

 

Crew seating capacity

1

 

POWERPLANT RATINGS

Standard Day at Sea Level

Franklin model 4AC-199-E (O-200-1)

100hp         73.55 kw

 

AIRCRAFT DIMENSIONS

 

Main rotor diameter (blade tip circle)

30’ 2”            9.14 m

Tail rotor diameter (blade tip circle)

7’ 0”              2.13 m

Fuselage length

27’ 11”          8.23 m

Length over-all (including rotors)

33’ 5”          10.06 m

Height over-all

8’ 10”            2.44 m

Main landing gear tread

12' 5"             3.66 m

 

Production History

 

Only one VS-300 was built. Although the configuration changed constantly during development the only change to the designation was to reidentify it to the VS-300A in the 3rd and 4th configurations.

 

Additional Information:

 

The link below is to a video: Recollections of a Pioneer, narrated by Igor Sikorsky’s son Sergei, which contains excellent vintage movies of the VS-300 and also some famous words from Igor.

http://www.youtube.com/watch?v=RmlY8-2OuhQ&list=UUTJoP1HY16QwaGyTJATWMLw&index=31

 

September 1999  Sikorsky Archives News  “60 Years Ago A Vision Flew”

http://www.sikorskyarchives.com/news3/index.html

 

Anything A Horse Can Do.  The Story of the Helicopter

H. F. Gregory (1944) ISBN-10: 1430497505

 

The Story of the VS-300.  The Aircraft that Launched an Industry

Harry Pember   Igor I. Sikorsky Historical Archives

 

Pioneerinng the Helicopter

Charles Lester. “Les” Morris (1945

 

 

NOTE: Links in this document to websites outside the Archives site are provided to supplement the information provided.  A reference to these sites does not constitute an endorsement nor a confirmation of the historical accuracy of the information by the Igor I. Sikorsky Historical Archives, Inc.

 

 

Prepared by Vinny Devine

January 2013

 

 

 

for Additional reading see NEWSLETTER JULY 2013
and
NEWSLETTER JULY 2012

 

 

 

last update MARCH 4, 2014

 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
 
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