This document contains information provided by Manny Osias, a former YS-11 pilot for Aboitiz One airline and current DC-9 First Officer for Cebu Pacific airlines in the Philippines. Many thanks for his assistance!
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FLIGHT CHARACHTERISTICS:
These figures are based on a 320 nm flight:
Airport elevation 75 ft MSL
Temperature 30 deg.
Average takeoff weight: 54,000 lbs.
Fuel: 6,500 lbs and 60 gals of Water Methanol
Taxi: Throttle position is moved from idle to approximately 1/2 the throttle range. Once the plane starts rolling, you can pull the throttles back to 1/4 position throttle range. Steering is done through a tiller on the Captain's side, with average to fairly light pressure because the steering is hydraulically boosted. The flight controls are locked in the neutral position by a mechanical lock.
There are no condition levers as in the Kingair (which I also flew). The YS-11 has a "high pressure fuel cock" similar in principle to a jet's "fuel levers" It has the following positions: OFF - fuel valves closed, ON - fuel valves open, fuel can be introduced into the engines, and HIGH STOP LOCK WITHDRAWAL - a position that manually retracts a safety lock in the propeller mechanism. None of these positions affects engine speed (N2) as in the case of the Kingair's condition levers.
The YS-11 also has no prop pitch levers, nor does it have a prop RPM gauge. The propellers are "hydromatic" and blade angle (pitch) changes are dependent on power settings - constant speed type. The pilots have no control over the actual blade angle pitch. The airplane does have a "low stop" lever which withdraws a low speed mechanical lock in the propeller mechanism and allows the blade angle to be set to 0 degrees during landings (called "ground fine pitch), with the throttle at full idle. The engine has no reverse thrust and relies on the drag created by the 0 degree pitch spinning propeller and wheel brakes to decelerate for landing. The low speed lock prevents the propeller from going into the "ground fine pitch" range during flight (doing so would be disastrous!) The ground fine pitch ranges from 0-13 degrees below the low stop lock. Above the low stop lock, "a flight fine pitch" of 14 deg. is the minimum blade angle with the throttles at the idle position. Cruise blade angle is approximately 27 degrees. The low stop lock lever automatically advances to the high position when the throttles are advanced for takeoff. However, it must be manually placed in the low position during landing, as soon as all three wheels are firmly on the runway.
The RPM gauge in the cockpit measures "engine" speed rpm - N2 turbine. During taxi, normal engine speed is approximately 12000 RPM and the fuel flow ranging from 350-500 lbs per hour per engine.
TAKEOFF:
There are two types: WET - utilizing Water Methanol boost, and DRY - without Water Methanol boost. Procedures usually call for a Wet takeoff when the takeoff weight exceeds 48,000 lbs or when operating out of runways less than 6000 ft long. It is possible to do DRY takeoffs if the runway is long enough (around 9000 ft.) even at high takeoff weights, however, this isn't recommended. Flap setting for a "wet" takeoff is 10 deg. Flap setting for a "dry" takeoff is 15 deg. During a wet takeoff, the engine speed is 15000 RPM with a TGT of 860 deg Centigrade. For a dry takeoff, you get 15000 RPM with a TGT of 820 deg Centigrade. Take note, your only indication of the power difference between a WET and DRY takeoff is the TGT. However, a WET takeoff will give you 3,060 SHP, while a DRY takeoff will give you 2,400 SHP. During a wet takeoff, Water Methanol is sprayed directly into the combustion chamber once the engine speed passes 14000 RPM. Fuel flow during takeoff is approximately 1600 lbs/engine.
Rotate speed is 105 knots for a MTOW takeoff, with a pitch angle of 8 degrees nose up. Initial climb rate is 1000 fpm. Once the gear and flaps are retracted, the water methanol system is turned off, and climb power is set at 14500 RPM with a TGT of around 790-800 deg centigrade, fuel flow around 1100-1200 lbs/engine. Pitch attitude is around 8 degrees with an initial climb rate of 1000 fpm. Throttle position is approximately 3/4. The YS-11 is somewhat underpowered. average climbe rate is around 500 fpm. At 12,000 ft, you get a measly 100 fpm. Although the manual lists a service ceiling of 25,000 feet, the highest I ever got in a YS-11 is 14,000 ft. This was in an empty airplane with very little fuel!
The YS-11 is a very gentle & docile airplane in a stall. It remains wings level and just noses over slowly. It stalls clean at 85 knots and 74 knots in approach configuration (gears down flaps 35).
Feelwise, the YS-11 is a fairly heavy airplane and the control responses are quite sluggish. The flight controls are not hydraulically boosted, only aided by "control tabs" which move in the opposite direction of the primary control surface. For example, if the elevator moves down, the control tab moves up, thereby helping relieve control pressures by aerodynamically pushing the primary control surface in the proper position and angle. Control feel for the YS-11 100/200 series seems heavier than for the 500 series aircraft.
It's difficult to say anything about actual flight characteristics of the YS-11 because each one has a "unique" charachteristic. Most YS-11's would "drop" onto the runway once you reduced the power, meaning most of the time, you actually landed with a little power. I have flown some airplanes, though, that seemed to stay in the air forever, even with the throttle at flight idle. Each plane is rigged differently, even from the factory. 100% consistency is impossible and this accounts for each airplane having a unique "personality." It's the same with the DC-9's I fly now. Some are "sinkers" while others are "floaters."
You'll have to wait a while for the flight model comparison, because I haven't flown your YS-11 in quite some time. I'll get back to you as soon as I can though, with any information that might be helpful.
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Normal cruise altitudes for the YS-11 are between 9,000 to 15,000 ft. Standard temperature here is 30 deg centigrade (ISA +15).
Can you e-mail me your postal address where can send diagrams? I have detailed drawings of the YS-11 panel. I tried scanning them, but the scans came out unclear. Also, the file size isquite large. Sending them to you by regular post might be better. I'll get you the pictures as soon as I can.
The ADI/Flight director is a standard "crossbar" type, much like the ones on other airplanes, with the usual heading/pitch, NavLoc, Approach & Back Course modes. It is important to note that these modes affect the FLIGHT DIRECTOR CROSSBAR only and are completely independent of the autopilot modes and operation.
The autopilot is very basic. Pitch & rate of climb are adjusted by a "pitch" wheel. Aircraft attitude (& rate of climb) are directly proportional to the pitch wheel displacement (forward movement causes the nose to go down and vice-versa). Altitude is held by "zeroing" the pitch wheel. There is no "altitude hold" function. There is a turn knob which controls the airplane's angle of bank. The turn knob displacement (left & right) is directly proportional to the bank angle. Maximum bank angle is 30 degrees using this knob. There is a heading select toggle switch (on/off) which allows the aircraft to be turned using the heading bug on the "Pictorial Deviation Indicator" or PDI (which is similar to an HSI). When turning the aircraft using the heading bug, bank angles are limited to 25 degrees. Turn knob inputs override the heading select mode. Other modes are: NavLoc (which captures radials set on the PDI), approach (ILS coupled) and back course (like NavLoc, but corrects for reverse sensing). There is no autothrottle system.
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Hello! In response to your question about the blade angle and low stop lock of the YS-11, when you advance the throttle to a point where the propeller blade angle will increase above 13 degrees, the low stop lock is AUTOMATICALLY disengaged, allowing the blade angle to increase. The low stop lock is AUTOMATICALLY disengaged (low stop lever moves full forward) when the throttles are increased into the takeoff range (the associated low stop lock lights extinguish). On landing, The low stop lever must be MANUALLY engaged (lever pulled to the aft position. As I mentioned in a previous e-mail, I managed to go flying in a YS-11A-100 test flight recently, so I have a better, more accurate description of the flight characteristics for you. Prior to this, my last flight in a YS-11 was 6 years ago. Here are my notes of things I have not mentioned to you previously:
There is a tendency to "nose up" when the flaps are extended during approach but this is easily controlled. A strong nose up tendency is experienced when the flaps are retracted ona "balked" landing or missed approach. Use of the trim tabs is required to keep the yoke forces tolerable during missed approaches.
There is no change in attitude during landing gear extension/retraction.
At low speed, an increase in engine power while retracting the flaps causes a nose up trend. While extending the flaps at low speed, there is a trend to nose down and bank to the right (right wing low), however, these are easily controlled.
During engine out operations, at speeds at or above Vmc, it is possible to fly the airplane without using the trim. At speeds below 120 knots with the rudder deflected approximately 10 degrees, rudder buffeting occurs.
STALLS DURING LEVEL FLIGHT
Impending stall is noted by vibration of the airplane (shaking) due to buffeting of the tail. The vibration is evident in any configuration and increases as the speed decreases.
The approaching stall is noted by an increase in a "nose down" tendency. A yoke force of approximately 80 lbs is needed to keep the nose up in order to stall the airplane. A change in configuration (flaps and/or landing gear extension/retraction) does not change this characteristic
There is a strong tendency to roll to the right (right wing low) during the stall. This is most apparent at high flap settings and high engine power. In some cases, a control wheel deflection of up to 60 degrees is required to counter the rolling tendency. Configuration changes do not affect this rolling tendency.
There is almost no yawing tendency during the stall, even during single engine operation stalls.
During Accelerated stalls ( stalling while turning or pulling up), the nose down and roll tendency is much greater than during normal stalls. Both opposite aileron and rudder deflection is required to counter the roll to the right.
SINGLE ENGINE TAKEOFF
On an engine failure at or above V1, when the torque pressure of the failed engine goes below 45 psi, the propeller will auto-feather. Yaw and roll tendencies are easily heavy, but the airplane can be controlled without using trim. Flap retraction may be doneat 400 ft AGL.
CRUISE
Normal cruising altitudes are between 10,000 to 15,000 ft. using the engine parameters I gave you in the previous e-mail.
HOLDING
Holding is done in clean configuration (flaps retracted) between 140 to 150 knots. For maximum endurance and fuel savings, the holding is done at 130 knots.
NORMAL DESCENT
Engine speed is set at 11,000 rpm with a troque pressure of 60 psi. Descent speed is 170 knots with a rate of descent between 1,200 to 1,400 ft/min.
CRUISE DESCENT
Engine speed set at 14,200 rpm. With a descent speed of 240 knots, the descent rate is between 1,200 to 1,700 ft/min.
EMERGENCY DESCENT
High speed - Flaps and landing gear retracted, torque pressure set at 60 psi, descent speed at 244 knots (Vmo), descent rate is between 2,400 to 3,000 ft/min.
Low speed - Flaps 35, landing gear extended, torque pressure set at 60 psi, descent speed of 135 knots, descent rate between 2,200 to 2,800 ft/min.
LANDING
Joining the traffic pattern downwind, speed is 140 knots and flaps are extended to 10 deg. Turning base, extend the landing gear. When the landing gear indicator shows the gears fully extended, lower the flaps to 20 deg. and begin a gradual descent. Turn to final approach at approximately 600 ft. and lower the flaps to 35 deg at 110 knots. Slow to Vref over the runway threshold. Close the throttles fully just before touchdown (aircraft attitude is between 3 to 5 deg nose up) and when all the wheels, are on the ground, pull the low stop lever to the GROUND (full aft) position. On crosswind landings, a 5% increase in airspeed is added to the calculated Vref speed.
Regards,
Manny
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Engine Start Sequence - The real YS-11
A brief description:
Starter Master Switch:
Start position: electrical power is supplied to the starting system
Safe: no electrical power is supplied to the starting system
Blowout: Power is supplied to the Starter motor, but ignitor is not energized (used for elimination of unused fuel in the engine)
Engine Select Switch:
1: electrical power is supplied to the LEFT HAND starting system
OFF: no power is supplied to either system
2: electrical power is supplied to the RIGHT HAND starting system
Start Push button switch:
Used to commence the start. When pushed (ON position), the starter motor begins operation (cranks the engine). The button will remain depressed until 30 seconds have elapsed or the engine reaches 4,500 RPM, whichever comes first.
Relight Switch:
Used when starting the engine without using the starter motor - like in-flight re-starts. ON position provides continuous ignition.
Starting Motor indicator lights:
illuminates when the starter motor is in operation
Ignition indicator lights:
illuminates when the relight switch is turned on
Normally, startups are powered by an external power source, however, in case a start has to be made using the internal battery, the procedure is as follows:
1. All non essential electrical items are turned off. Normall only the anti-collision light and one fuel pump is turned on.
2. Start master switch to START position, Engine Select switch to "2" position (right engine). Propeller Startup area is cleared by Maintenance personnell.
3. Push the start Button and wait for 1200 to 1500 RPM, then move the High Pressure cock form FUEL OFF to "FUEL ON"
4. Monitor the engine gauges for abnormalities while waiting for the starter button to pop out.
5. When the Start push button pops out, and the indications remain relatively stable for 5 seconds, turn on the remaining #2 fuel pump & #2 (RIGHT hand) generator and check the #2 ammeter.
6. If the meter indicates greater than 200 amps, wait until the reading drops below 200 amps before starting the #1 (LEFT hand) engine.
7. When the amp load indication on the #2 generator goes below 200 amps, leave the #2 generator ON, move the ENGINE SELECT SWITCH to the #1 position (LEFT hand engine), all the #1 engine fuel pumps and Start that engine using the same procedure described above.
Simple isn't it?
In effect, after starting the #2 engine, #2 generator power is used to energize the #1 ignition system instead of the battery (called a Cross-generator start). The Ammeter load indicated after starting the #2 engine means that the internal battery is re-charging. The internal battery system consists of two (2) 24 volt Nickel Cadmium (NiCad) rated at 22 Ampere-hours (AH) located in the left & right engine nacelles, connected in parallel with the DC bus through a 200 Ampere limiter and battery relay. The YS-11 also has a 24 volt 1AH RESERVE battery located on the right wall of the belly cargo bay connected to a Crash (emergency DC) bus.
