The UH-IX is a new, experimental high performance helicopter utilizing the latest in electronic control systems and stabilization.
Features include a state-of-the-art electronic instrument console; an on-board computer that regulates and monitors ships systems as well as providing pilot commands for special functions; automatic pitch control/engine power for RPM equilibrium including synchronization of anti-torque pitch unless directly controlled by the pilot.
Also employed is a new VLW (very light weight) piston engine molded woth a super strength, super light material, still classified by the military, which rivals the weight/thrust ratio of most torboshaft engines. Mounted vertically, the engine is coupled to the main rotor shaft through a custom/direct drive transmission system with a 10 to 1 reduction ratio.
The rotor assembly consists of semi-rigid blades and a hub articulation system that is electronically of semi-rigid blades and a hub articulation system that is electronically adjustable through varying flight conditions. The effect of this system is to reduce drag by 40 to 60 per cent and increase foward potential subststantially.
Structurally based on Bell Helicopters' UH-1 series, the UH-1X fudelage is made of a carbon-fiber material and molded for optimum aero-dynamic characteristics and low weight.
The streamlined interior seats one pilot in front with room for one passenger or co-operator directly behind. The main controls are incorporated into one stick, a revolutionary and conventional helicopters.
While this arrangement offers some new problems for novices and experieced pilots, it also provides a few advantages necessary for the UH-1X configuration. It allows for solo flight, enabling the single pilot to control the craft while at the same time control the on-board computer, radio or weapons controls. The fuselage is vunerable to weapons fire although the material has an elasticity component which can resist or deflect hits better than metal exteriors.
The Weapon System includes rockets that can be armed in sets of four and fired at one-second intervals. Two machine guns are mounted on either side of the fuselage and the fire in tandem. Maximum rocket supply is sixteen and the guns have 2000 rounds each. The UH-1X was not specifically designed as a military aircraft. Its high speed and long range is useful for reconnaissance or rescue and its armaments provide adequate defense capability.
The UH-1X reperesents a step in a new direction in helicopter flight design and control.
The physics of flight are the same for fixed wing and rotary wing aircraft but the helicopter introduces some complex problems over airplanes. In the first
place, airplanes are inherently stable whereas helicopters are inherently unstable. As a result planes require less constant controlling than do
helicopters. Both the wing of an airplane and the rotor blade of a helicopter
are 'airfoils" and interact with the air in the same way through the
'Bernouli' effect. Briefly describe the effect of the curvature of
a wing causing a higher air pressure area below the wing and a low pressure
area above, producing lift, as the wing moves through the air. A fixed-wing
craft requires forward thrust to producd lift. A helicopter blade achieves
forward thrust by spinning on a stationary axis thus producing lift only in
a direction parallel to the axis, or vertical thrust. The amount of lift dependson the 'angle of the airfoil' the angle of the blade to the relative wind. The angle of attack is proportional to the pitch of the rotor blade which is controlled by the pilot, greater pitch producing more lift. At the same time, as pitch increases, sodoes drag since more blade surface is presented to the airflow, and consequently, more power is required to maintain the rotor RPM.
The relationship between pitch and RPM is perhaps the most imortant considerationin operating a helicopter. Another factor in a rotary-wing system is the torque reaction of the spinning rotor on the fuselage. The torque of the turning rotor exerts an equal and opposite force on the body of the craft causing it to turn opposite to the blades unless counteracted by another force,in this case the tail, or anti-torque, rotor blades. The tail rotor provides thrust in a direction opposite the torque reaction, thus equalizing the force and stabilizing the heading of the craft. Further, the thrust of the tail rotor is controllable by the pilot providing direction control. This is possible because over compenstaion of the torque effect will turn the fuselage in the direction of the spinning blades and a thrust less than the force of torque will allow the fuselage to turn against the rotor direction.
Four main control systems are found in conventional helicopters. These are the cyclic stick, the collective pitch contol, the throttle and the anti-torque
(or rudder) pedals. The collective pitch control, or simply, collective, increases or decreases the pitch of all blades equally. The collective is the primary vertical thrust control. Normally, pulling up on the collective stick
will produce lift and lowering it will decrease lift. As mentioned above, as ptich increases, so does rotor drag, reqiring an increase in engine power to maintain RPM. In many helicopters, this synchronization is provided auto-
matically by a link between the collective and the throttle.
The throttle controls engine power and RPM directly. It is usually located on the collective stick to aid in the coordination of pitch and RPM.
The anti-torque pedcals control the pitch of the tail rotor blades, providing torque compenstation and directional control. Normally these are conventional rudder pedals. Finally, the cyclic stick is the main direction control which determines the attitude of the rotor system. Basically, when the plane of the spinning rotor disc is horizontal, all the thrust produced is directed upward, perpendicular to the plane and parallel to the rotor shaft. By moving the cyclic stick in any direction away from center (or neutral) the plane of the rotor, in essence, tilts in the same direction, thereby dividing the thrust between the vertical and tfhe direction of tilt. For example,moving the cyclic forward will cause forward thrust to a degree which is equal to the amount of rotot deviation from the horizontal. At the same time the attitude of the fuselage will change o the same degree (in forward flight, a nose-down condition). Also, a cyclic change will change the "angle of attack" set by the collective pitch control, which will affect RPM and thereby, torque reaction.
This illistrates an essential characteristic of helicopter controls. Any change in one of the controls will, in most cases, require some adjustment in the other controls. This is why helicopters must be "flown"; at all times.
In conclusion, the four main control systems can be thought of in general as follows:
The cyclic controls the direction and attitude of the helicopter. The collective controls the amount of thrust produced by the rotor blades in the direction set by the cyclic stick. The throttle directly controls engine power output and RPM. The anti-torque pedals control torque compenstation and directional contol to maintain heading.
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THE UH-IX CONTROL SYSTEM
========================
The Super Huey Control System can be diveded into two main components. The control stick and the computer keyboard.
The UH-IX keyboard design is based on the Apple II computers with primary switches for on/off (key 1), the engine starter button (key 2), rotor clutch engage(key 3) and engine off/cut power (key 4). The remainder of the keyboard is used to enter commands and data to the on-board computers, or fly under keyboard control.
The control stick is a new approach to helicopter control, housing all four of the normal control devices into a single unit. The stick itself is not dissimilar to a video game controller (called a "Joystick") incorporating an 8-postion pivoting hand-grip and a single activation switch (or fire button).
The UH-1X Control operates in two modes: the cyclicmode, wherein the stick acts almost preciselylike a normal helicopter cyclic control stick,and the collective mode, wherein the stick affects blade pitch angle and the throttle.
The cyclic mode is in effect when the fire button is not depressed and the collective mode engages wshen the fire button is depressed.
The schematic illustrates the function of the UH-1X control stick. A geographical convention will beused to indicate the direction of stick move-
ment. For example, pushing the stick forward, or away from the pilot, will be designated as North, and pulling back on the stick or toward the pilot, will be designated as South.
The inner circle describes the four operations of the collective mode which is engaged by prfessing the fire button. Pushing the stick Northj will decrease the pitch angle of the rotor blades, thus reducing lift/thrust to a point of
O angle of attack or no lift. Pulling back South will result in a blade pitch angle increase producing more lift/thrust. Pushing the stick West will in-
crease the throttle opening producing more engine power and a higher RPM.
A push to the East will close the throttle gradually, reducing power.
The Fire Button is used to switch from cyclic to collective mode unless weapons
are activated.
The outer circle describes the function of the stick when in cyclic mode (the fire button is NOT despressed) A North movement of the stick will tilt the rotor forward resulting in forward thrust. Moving the stick South tilts the
rotor back to counter the forward thrust,thus slowing the craft. If held long enough, the helicopter will come to a stop supplying only vertical thrust for
hovering. East or West stick movements will result in a hard banking turn in the same direction. Stabilizers will level the ship as soon as the stick is
returned to center. Northeast/Southeast stick will change the heding to the right through use of the anti-torque, or tail, rotor. Northwest/Southwest
will produce a change to the left. Small course corrections should be made with the rudders and significant turns should be handled by banking the ship left or right. With exception of hard bank left/right turns, all other control changes
are designed to "set and hold" in both cyclic and collective mode. This means
any change in flight attitude by the control stick will be continuous until an
opposite control maneuver is executed by the pilot to the same degree.
For example,pushing the stick to the northwest will lessen tail rotor thrust thus allowing the fuselage to begin turning to the left. The longer the stick is held in that direction, the greater the reduction in tail-rotor thrust. Re-
turning the stick to center will not eliminate this change. The pilot most move the stick to the northeast to begin counteracting the thrust change which
will bring the level of anti-torque effect back to neutral to reestablish a straight-ahead attitude. Similarly an increase in lift produced by moving the
stick south, in the collective mode, will build vertical thrust which will
remain the same until the collective is lowered (stick north) reducing lift. If the lift is not enough to overcome the weight of the helicopter, then it begin to descend (this is how landings are accomplished). Only experience will
allow the pilot to discover the precise points of equilibrium required to achieve the desired maneuver.
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INSTRUMENTS
===========
1 - FRE - VHF Omnidirectional rnge transmission from a local station or base
used by the navigation computer to set a heading to the transmitting
station.
2 - NAV - Compass heading computed from the VCR Transmission (1) The COR
Command may be used to copy this heading to the automatic course setting
(2) or the NAV heading may be followed manually.
3 - RAD - Radar is activated by entering combat mode (LAR Command). This read-
out then gives the line-of-sight range of the radar trace from the heli-
copter (multiple traces are resolved to the closest target).
4 - ARM - Numbers 1 2 3 4 are lighted indicating which rockets are in launch
tubes (1 to all 4 are selectable). The indicator lights below the numbers
show which rockets are armed and ready to fire.
5 - HOM - A homing device may be dropped using the HOM Command. The heading
to return to the drop spot is then transmitted and displayed here. The
homing device has a range of 20 miles.
6 -RES - This displays the transmitted heading of a homing device used by
ground personnel to be located. This readout will activate (and take
precedence) when in range.
7 - INDICATOR LIGHTS - Routine automatic systems check will light the
appropriate indicator if a malfunction is found in anhy electornic system.
The pilot has no control over such malfunctions and should return to base
for repairs.
8 - FUL - Fuel gauge
9 - OIL - Oil pressure gauge. Optimum reading is center mark.
10- TMP - Engine temperature gauge. Normal cruise reading is center mark.
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COMPUTER CONTROL
================
Operation Press key Note
---------- --------- -------
Computer ON/OFF 1 *
Engine Starter button 2 *
Rotor clutch engage 3 *
Engine Off/Cut power 4 *
--> * NOTE- See Take-Off & Flight Procedures
=======================
KEYBOARD OPERATION ONLY
=======================
Operation Press key
--------- ---------
To select the keyboard operation /
Deacrease lift ;
Increase lift p
Increase throttle W
Decrease throttle Q
Increase foward thrust A
Decrease foward thrust Z
Bank left Left cursor
Bank right Right cursor
Return to level flight Space bar
Left rudder <
Right rudder >
Fire Space bar
Select joystick /
============================
ON-BOARD COMPUTER COMMANDS:
============================
To enter command mode press the ESC. key this prepares the keyboard for entry of three letter on board computer commands.
To abort command entry press the ESC. key and enter the correct command.
=================
COMPUTER COMMANDS
=================
ABT - Abort the current mission. End assignment and stop all activity
ACS - Set automatic course correction. When prompted by SET, enter compass heading. ACS works only when there is no manual control input.
ASN - Select a new assignment,and enter one of the following
INS - Flight instruction
EXP - Exploratory mission
COM - Combat
RSC - Rescue Mission
CLM - Displays current climatic conditions including temperature, humidity, air
density and pressure, and barometric reading.
DST - Calculate line-of-sight distance from take-off point.
GTK - Displays map grid for ground tracking based on Homing signal.
HOM - Drops a homeing device that transmits directional signal to the navigation computer.
LAR - Load and arm rockets. At the load prompt, enter numbers 1-4 to select
the number of rockets loaded into the tubes. At the ARM prompt, enter numbers 1-4 to arm the rockets. The fire button is then engaged for firing.
MAC - Activate machine guns.
POW - Turn on power
SAF - Send coordinates when landing or during emergency.
RAD - Turn on radar tracking without engaging weapons.
TRK - Displays grid for radar tracking and targeting.
VOR - Activate VHF Omnidirectional Range reception for navigation.
VSI - Display vertical speed reading.
XXX - Cancel previous command input. (not available on immediate action commands.)
================================================
STANDARD TAKE-OFF, FLIGHT AND LANDING PROCEDURES
================================================
1- Turn on the computer (1) Enter ASN to select an assignment. Enter three-
letter designation for mission. Standby for computer collating.
2 - Enter POW command to turn on power.
3 - Start the engine (2) Increase Throttle tobring engine RPM to 1600-1700.
4 - Engage Rotot clutch (3) Wait for rotor RPM to reach engine RPM, Monitor
Oil pressure gauge and Carburetor gauge for normal operating levels. Also
watch for high or low temperature levels.
5- Increase throttle to build RPM to take-off speed (3000-3100 engine, 300-310
rotor).
NOTE: If helicopter has been previously operated, make sure collective
pitch is at FULL LOW before increasing throttle.
6 - With engine at proper RPM begin to increase pitch with the control stick
(collective South). As lift is attained watch for wind drift and stability.
Control position and heading with Rudder control cycle (cyclic NW,NE,SW,SE)
Continue to control pitch angle as necessary to obtain smooth vertical
movement. Equalize lift to attain a stationary hover at 20-30 feet.
7 - Select heading with the rudder control and begin moving the control stick
in cyclic mode, forward (cyclic North). As some airspeed is achieved, add
more collective pitch to go into a climbing forward attitude. Forward
cyclic will increase RPM due to a throttle link. It is most important to
hold RPM at a constant rate during cyclic/collective adjustments. Also,
forward cyclic will tilt the fuselage forward toward bringing the nose
down. Hold the ship at the proper attitude with some back cyclic mod-
ification. Increase forward thrust and airspeed with the collective con-
trol rather than further cyclic control to maintain attitude but monitor
the degree of pitch and manifold pressure to stay at safe levels. Keep
in mind that holding the control stick too long in any position will
result in over-controlling. Make adjustments small and gradual to achieve
a steady and controlled rate of change.
8 - Bring airspeed to between 70 and 90 knots and continue climbing to at
least 500 feet, a minimum altitude from which to make an autorotative
landing in the event of engine failure.
9 - Once desired altitude is reached, decrease collective to a point of equilibrium to enter straight-and-level-flight.
10 - Once in straight-and-level flight, maintain altitude and airspeed with cyclic and collective control and hold your course with the rudders.
11 - To return to base, enter a full 180 turn wuth cyclic West or East.
Watch the compass to follow your heading through the turn. Slightly
before reaching your desired return heading bring the control stick back to the center and begin leveling off.
12 - Begin the descent by gradually decreasing pitch. As altitude begins to fall, maintain airspeed with the cyclic control. Keep the rate of descent constant by collective adjustments. As the altitude reaches 100 feet, slowly begin to increase collective pitch to reduce vertical speed. Just before touchdown, add some degree of pitch increase to cushion the landingand once on the ground immediately decrease the pitch angle to the FULL LOW position.
13 - Cut the engine and power (4). The rotor clutch will disengage and gradually slow down to a complete stop.
