The goal of this text is to provide a comprehensive set of 'operating strategies', in plain English free from V speed jargon, for simulating the Handley Page Herald 200 within FS2002. They provide an insight into the role of pilot flying (PF) in an aircraft powered by early series Rolls Royce Dart engines during the classic era. Today with turbine overhaul facilities everywhere, forty-five extra years of experience, and some engine modifications along the way, higher rpm limits apply. This is all about experiencing the first decade or so of turbo prop engine operations.
Some aspects of Rolls Royce Dart operation conducted manually by the flight crew have been omitted, combined, or automated because they would be undertaken by pilot not flying (PNF). Unfortunately the accuracy of the simulation is further constrained by the capabilities of FS2002.
Contrary to popular opinion FS2002 does not contain 'a turboprop flight model'. It just contains a flight model for one particular concept of turboprop engine, (the P&W PT-6A). This third generation turboprop engine allows the pilot to vary airscrew rpm independently from fuel flow. First generation turboprop engines like the Rolls Royce Dart lacked that capability. The power and thrust output of early generation turboprops can be simulated correctly within FS2002, but pilot inputs cannot.
Aircraft powered by the Rolls Royce Dart have power levers, which control both fuel flow and engine rpm together. This can be simulated in FS2002, but only at the expense of suffering inaccurate rpm output as a consequence of the rpm linking to fuel flow. When flying a Dart engined aircraft in FS2002 never attempt to change engine rpm, prop rpm, or prop pitch with keyboard inputs or joystick buttons which emulate such keyboard inputs. Dart rpm must be controlled using the joystick throttle alone.
The Rolls Royce Dart is not flat rated. As it climbs through the atmosphere, and air density falls, the power produced falls in step. In FS2002 the turbine rpm will also fall in step. This is not realistic, but it is the price you have to pay for elimination of the non-existent rpm levers whilst maintaining realistic power (and thrust) output.
The engines are tough, and only significant abuse in flight would cause them to fail. In the commercial world however aircrew must operate to much more restrictive engine limits, imposed by the engine manufacturer and airline, which ensure that the engines need maintenance as infrequently as possible. Turbine overhauls are very expensive.
Unlike a piston engine, the power that a turboprop produces varies considerably with outside air temperature. Many later turboprop engines had automatic temp trim to take care of the problem, but the Rolls Royce Dart, which has been in airline service since 1949 does not. Pilot Not Flying will take care of most of the manual temp trimming with the temp trimming switches. In FS2002 acting as Pilot Flying you must limit Turbine Gas Temperature (TGT) using your joystick throttle. If you never fly with real weather, or with high temperatures selected from the weather menu, this may not be much of an issue, but you will never really get the most from this flight model if you do not explore Dart operation in high temperatures.
Here is a phase-by-phase strategy guide for simulating the role of pilot flying in a Herald 200 within the limitations of FS2002.
OPERATING STRATEGIES.
1) The take off
The Dart 527 has water methanol injection. Invented in Germany during WW2 it was originally a means of adding war emergency power to piston engines. When employed with turboprop engines its usage is rather different. Whilst it always adds some extra power, its purpose is to restore the rated power of the engine in high outside air temperatures, but only for the duration of the take off. In principle it allows the gasses to enter the most critical parts of the engine at higher temperatures, because it provides additional cooling. It is not a form of reheat or rocket boost.
It is standard operating procedure to use it when available. Selection of water methanol injection for take off has therefore been automated in FS2002. The injectors will operate as the TGT exceeds the normal limits. The TGT does not fall. The point is to allow it to be higher.
When you make a wet take off the TGT can rise safely to 825C. Whether TGT ever gets near 825C will depend on the outside air temperature (OAT). The OAT will have to be high for the wet limit to be breached, but this may happen outside the temperate climate of Northern Europe. In a temperate climate you will almost always be able to use full throttle for a wet take off but 825C is the limit, not a target. At sea level you will obtain about 1,870 SHP at full power lever advance, but less at altitude. Water methanol injection 'cancels' high outside temperatures, but as deployed in the Dart 527 it does not significantly compensate for thin air on high runways.
Some airlines fly from A to B. Others fly A - B - C - D without refuelling or topping up the water methanol tanks at B and C. You have enough water methanol for one, or perhaps two, wet take offs and one go around. On a bus stop route one or two of the three take offs will have to be made dry.
Without the benefit of water methanol injection the TGT limit is only 795C. When performing a dry take off with an OAT above freezing, always advance your joystick throttle much more carefully to temp trim the engines to less than 795C. It is a limit not a target. You will only be able to apply full throttle during a dry take off if the outside air is very cold.
The lower the engine limits the less power you can generate and the longer the take off run. If flying for a bus stop airline, from runways at normal daytime temperatures, choose which of the runways at A, B and C will be favoured with wet take offs with care. Practice dry take offs at < 795C in high OATs as well as wet take offs at < 825C, but make sure the runway is long enough for the prevailing temperature.
After take off make sure you do not exceed 110 KIAS until the noise abatement phase is completed. After noise abatement retract the flaps and only then allow the aircraft to accelerate to 120 KIAS.
2) The climb
Since you do not have enough water methanol to use during the climb, (water is very heavy and the airline would rather fill seats), all your climbs have to be made in dry power. Even if you made a wet take off you must get the TGT back to < 770C after the take off. The injectors stop of their own accord. If it is cold enough outside the TGT may already be below 770C.
It would be perfectly safe to climb the aircraft all the way to cruising level at full throttle and 795C. The engines would however need frequent expensive overhauls and you would soon need to look for alternative employment. As soon as you have complied with the noise abatement rules in force you must reduce to a profit maximising rpm setting and observe a lower TGT limit.
Until the end of noise abatement flight safety and excessive engine wear have been the only considerations, but now you must also take into account fuel economy. From this point onwards achieving the target RPM for fuel economy has priority over engine wear considerations unless the TGT limit may be breached. Breaching of the TGT limit implies that your pursuit of fuel economy is costing too much in engine wear.
Reduce to 13,800 rpm, but if TGT exceeds 745C you must reduce further.
As you climb the amount of oxygen in the air reduces and the engine produces less and less power. In FS2002 you must gradually advance the throttle to sustain 13,800 rpm, but eventually air density will be too low to sustain 13,800 rpm in FS2002 at full throttle.
This altitude is the lowest cruising altitude consistent with sustained economic operation of the aircraft, but unless you are flying a very short stage you will always want to climb higher. Thereafter in FS2002 you climb at full throttle and in FS2002 rpm will fall steadily. Whenever Dart 527 engine revolutions fall below 13,000 rpm you must limit TGT to no more than 715C.
You will be climbing with less than maximum continuous climb power. Consequently you must now reduce your rate of climb so that you can continue to maintain 120 KIAS. Although the loss of rpm is a function of the limitations of FS2002, the accompanying loss of power as you climb into less dense air is entirely real.
3) The cruise
Whilst a Dart 527 would not fail within the duration of a single flight, even if run continuously and dry at 850 C and 15,000 rpm, some aspects of the Rolls Royce guarantee concerning time between overhauls became void in the classic era if the aircraft was cruised continuously at more than 13,300 rpm. Designated 'normal cruise power' by the engine manufacturer this sets 'maximum cruise power' as far as the airline is concerned.
When conducting maximum cruise at > 13,000 rpm you are also limited to 745C TGT. In hot air max cruise may have to be conducted at less than 13,300 rpm. Hot air is associated with low altitudes. To cruise at maximum cruise power you must climb high enough to find cold enough air.
There is a profit maximising altitude for maximum cruise. It varies from day to day and place to place, but if expressed as a flight level it is usually close to FL160. It is the level at which you can set 13,300 rpm at the lowest possible TGT. It is much easier to find in FS2002, than in real life, as it will be the highest altitude at which you can sustain 13,300rpm. That combination produces the guaranteed maximum cruising speed.
In the case of the Herald 200 that is 239 KTAS (@ FL150). You will burn about 1600lbs of AVTUR per hour to achieve that.
In common with most turbine engined aircraft application of normal cruise power may accelerate the aircraft beyond its safe structural limit. The Herald has neither a Machmeter nor a barber pole ASI. Up to FL150 you must not exceed 206 KIAS as a result of applying more than economical cruise power. At high altitude transonic shock could destroy the aircraft. By the time you reach FL230 you are limited to a maximum of 174 KIAS. As a result of these transonic shock issues operation of the Herald above FL150 was rare. It is however entirely possible to climb to the structural limit of the pressure cabin at FL230. You just have to be very careful indeed to restrain your airspeed to no more than 174 KIAS during the eventual descent.
Structural integrity aside you should only apply maximum cruise power if absolutely necessary, to make up time and get back on schedule. Otherwise you should operate the aircraft using the economical cruise power setting.
For the Herald 200 this is 12,600 rpm. In principle fuel economy will suffer, but the savings in engine wear more than make up for the extra fuel burned. This condition is economical cruise. Since it is conducted below 13,000 rpm you are limited to 715C TGT. You will burn about 1300lbs of AVTUR per hour in economical cruise power.
Since rpm is the primary operating parameter in Dart engined aircraft the rpm gauge in the Herald 200 is designed to make setting maximum and economical cruise easy. In both cases the idea is to make the two needles form a single needle. Diametrically opposed to create a long single needle at maximum cruise (13,300) and overlaid to create a short single needle at economical cruise (12,600).
Practice this.
As these aircraft aged they were relegated to shorter and shorter stages until it was not worth climbing to FL150 to cruise. High altitude economical cruise was still 12,600 rpm, but old equipment needs nursing and on short hops at low level it may be sensible to cruise at only 12,000 rpm. Below 12,000 rpm specific fuel consumption is so high that it becomes impossible to make a profit. This therefore represents the lowest rpm you can sensibly apply for cruise.
If you suffer an engine failure, airline policy and the manufacturers guarantee on the other engine are of no consequence. In emergency you may divert with up to 15,000 rpm and up to 850C TGT applied to the good engine for as long as you need. It will have to be removed and overhauled after landing, but so what.
4) Descent
Reducing to less than 12,000 rpm for the duration of the descent is OK because you minimise fuel burn by staying high as long as possible. A cruise descent at say 12,000 rpm wastes fuel. Descend fast and late if ATC will allow, but make sure you make the mandatory levels in the standard arrival. Remember that you must not exceed 206 KIAS at any time and that the restrictions are much more severe when descending above FL150.
In descent your attention must also turn to the PSI gauges. You must sustain sufficient power lever advance to avoid the yellow arc at the low end of the PSI range. If the needle enters that arc you will not have enough power to maintain pressurisation of the cabin, or to run the de-icing systems.
Once you are low enough to depressurise the cabin, and also have an outside air temperature above 5C, you may reduce power into the yellow PSI range, but in everyday operation it should not be necessary.
5) Approach
The Herald was eclipsed by the Fokker Friendship which offered greater structural integrity in all configurations. The Herald is limited to 171 KIAS with the gear down and just 124 KIAS with any flap extended. If you are used to flying swept wing jets in FS2002, or simple flight dynamics with no structural limits in them, the idea that flaps cannot be used as air brakes in real life may come as a shock.
The low structural integrity of the Herald forces you to plan ahead for the descent and approach.
When flying turbine engined aircraft always aim for a stable powered approach. Use the rpm gauge to make one short needle at 11,550 rpm. Set this rpm before you enter the holding pattern, (up to thirty minutes before landing), and do not attempt to change it until two mile final.
Unless subjected to speed control by ATC do not play around with the power levers during the approach.
A couple of minutes before you intercept a 3 degree glide path, extend the gear. When you are below 124 KIAS extend full flap (F8 key). You are now ready to begin the final descent to land. In a Herald never begin the descent on the glideslope at more than 124 KIAS, or without full flap.
Practice flying the approach making one short needle at 11,550 rpm until you have learned to extend the gear at just the right moment to bleed your speed through 124 KIAS about 30 seconds before Glideslope intercept.
Depending on the strength of the headwind you may need to add or subtract a sliver of power over the last two miles (last 600 feet) of the descent, but sometimes the same power setting will be good for the last thirty minutes of the flight. If you do need to vary power from 11,550 rpm, after you are cleared for the approach, make slow small changes, to hold the 3 degree glide path, and achieve your reference speed.
The lighter you are the lower your reference speed. The reference speed for max landing weight is stated in the handling notes. It reduces with the square root of the landing weight. You must calculate your reference speed at the airfield boundary carefully and then flare to a lower speed before mainwheel contact if you wish to emulate the real short field performance of the Herald 200.
Always use the abbreviated pilot's handling notes, called by pressing F10 and selecting the reference tab, from take off to landing, until you have accumulated enough hours in the Herald 200 to know them off by heart. That way you will have a realistic flight simulation experience, the aircraft will remain under control, and you will not suffer structural failure.
Do not attempt VFR approaches or visual circuits in turbine engined aircraft until you have mastered the stable approach technique in that aircraft type. When you are finally ready to attempt an unstable visual approach give yourself lots of room. Never attempt to fly a visual approach in FS2002 with a zoom setting of less than 1.0 as human perspective will be so distorted that you will find it impossible to judge the glide path and will always wind up with a rushed approach.
6) Landing
When you land, the Dart has another trick up its sleeve. If you have the throttles sufficiently retarded microswitches in the main gear will detect weight on the wheels and will withdraw the flight fine stop lock from the airscrew shaft. The airscrews will fine to zero degrees (ground fine pitch) and will become pure air brakes even though the props are still turning.
This has nothing to do with reverse pitch or reverse thrust. They are not pushing any air forward, just adding drag. However since the effect is almost instant it is enough to ensure that the Herald does not need reverse pitch. The aircraft will slow almost as quickly in ground fine pitch. Raise the flaps (no restriction as there is no reverse thrust to hammer them), and when below 55 knots start to add wheel braking as required.
To exit ground fine pitch simply advance the throttles, but remember ground fine pitch will not invoke if you forget to retard the throttles after landing.
7) On the ground
This flight model does not attempt to replicate Rolls Royce Dart 'ground condition' operations in full. The rpm gauges will over read on the ground. Nevertheless ground pitch settings including ground fine pitch are simulated by alternative means and the net thrust produced versus joystick throttle position is 'realistic' during ground handling. Unlike the real aircraft you can switch from ground to flight condition simply by advancing the throttle.
8) In flight
Use the abbreviated handling notes Herald_ref.txt. Press the F10 key and then select the reference tab. Use them as a phase-by-phase and step-by-step checklist. When you open and close the handling notes they will remember where you left off, just like a flip chart check list. These in flight handling notes are in addition to any start up, pre flight and shut down check list which you may alias from the checklists tab.
Now you know enough to take on the challenge of flying, and then mastering, the Herald as a unique aircraft, with its own distinct limitations and characteristics, instead of just watch the computer fly yet another generic aircraft. I hope you find it to be an excellent introduction to flying turbine powered aircraft, just as many real world pilots have over the past forty-two years.
