From the archives: Leighton Collins flies a Lear 24

“8.8 Club” – from the May 1967 edition of Air Facts

By: Leighton Collins

When the small jets came along invitations to ride in them were far and few between, and invitations to fly them were almost non-existent. There was, of course, good reason for this. It is easy to go broke handing out free rides in airplanes. Every pilot wants an airplane, but somehow or other only the ones who can pay for them ever seem to buy them. The salesman who survives soon learns this and concentrates his demonstrating on those who can buy if they want to. Not unsurprisingly, one of the jet salesman’s first questions was always, “Who do you fly for?” The bigger the corporation the faster things moved.

They had the additional problem of having an airplane it takes ten hours and a week’s ground school to learn to fly, unless you’re already a jet pilot.

This may be a bit oversimplified, but at least it led to a reappraisal at Lear Jet: in order to sell flying of any kind people have to have a chance to find out what it’s like. How else are they going to know whether they want to participate in it or not? They must have known at Lear, as well as elsewhere, that many a time already the boss has asked his chief pilot, “What about these small jets?” Knowing nothing about jets and having a smooth running operational and maintenance set up with one or more piston airplanes why disturb the status quo? In shaking their head on the jet questions some of these pilots might even have had secret doubts as to whether they could fly a jet, aside from the questions of whether they would like that type of operation. Why swap something sure for something unknown? There has been more than one case of a company pilot talking his employer into buying a DC-3 rather than a small jet. The latest one was only last week.

A Bargain

Air Facts cover 1967
This article first appeared in the May 1967 issue of Air Facts.

They hit on the idea of the 8.8 Club at Lear Jet, which solves many problems, not only for them but for a lot of people. It is a Jet Flight Familiarization Course for professional pilots. The 8.8 means you’ve flown 8 miles high at .8 the speed of sound at that altitude, or at Mach .8 as they say it. A lifetime membership in the Club is $350 and for this you get all necessary training materials, a full day’s ground school, and, on the second day, an hour on the left side in a Lear Jet. During this hour you take off, cruise, and land, thus flying one side of a triangular cross country. Then you get in the back and watch two other applicants fly the other sides. Classes start every Tuesday (Lear Jet Corp., P. O. Box 1280, Wichita, Kansas 67201) with a 7:40 pick-up at the Diamond Motel, which is near the Lear plant. You pay your own transportation and lodgings expenses. Classes are limited to six, this because the rest of the time the training staff and equipment are tied up with pilots who come in for a Lear Jet rating, which entails a week of ground school and ten hours’ flight time.

In the initial invitation mailing to pilots of corporation aircraft the only mistake Lear Jet made was in saying nothing about the size of the corporation, so when one came to Air Facts, Inc., we bunted and slid for first, winding up on the front row in the first course. It is doubtful that they’d be sticky about this professional pilot business. What they are probably trying to say is that they are looking for a multi-engine pilot with instrument proficiency. The latter would be more important than total time, since it is almost impossible to fly one of these except pretty much by instruments.

Arithmetic

School started on time, and it was a sprint all the way through. First and continuing emphasis was put on the fact that the jet airplane flies in accordance with the same basic principles as any other airplane and the main thing to be learned is the variations in these principles as applied to the jets. You need to know the variations in order to understand the techniques. Time and again, Bob Berry, the first instructor up, would say, “So, this is another variation.” They stress, too, the need for flying with much more precision than most non-jet pilots are used to. This is because with the piston airplane, flying “off the numbers” a bit may make really very little difference in over-all results. With the jets, though, stray only a little from the proper speed and the proper power and the penalties in performance are high. 10 kts excess speed in an approach, for instance, adds 1000’ to the landing distance.

By noon, the following is what we had tucked away as essential information in our forthcoming and eagerly anticipated joust with the jet.

Turbine

The jet engine is basically a very simple thing. The compressor, located in the forward part of the engine, packs several tons of air per minute into the combustion chambers behind it, fuel is pumped in, there is continuous ignition from the heat of compression, and the hot air blows out the open rear end of the combustion chamber or chambers, at a great rate. As it goes out, it passes through a small windmill, or turbine, which recaptures some of the energy and sends it back to the compressor by direct shaft, to turn the compressor. Otherwise the accelerated hot air and products of combustion just go. The jet engine, then, produces thrust by accelerating a mass of air, the net thrust being equal to the mass of gas times the change in velocity through the engine.

Push

The current method of measuring this acceleration or thrust output of the engine is by a couple of EPR (pronounced eper) gauges at the top of the engine-gauge instrument stack on the panel. EPR means engine pressure ratio. It is the ratio between the engine inlet pressure and the engine exhaust pressure. On each take-off the proper EPR is picked off a chart or table from the operating manual, which takes temperature, and pressure altitude into consideration. When early in the take-off run, you EPR needles go to the bug which has been set for this take-off then you know the engines are producing the thrust on which your takeoff calculations have been based. The jet engines are so smooth and quiet (in the cockpit) that without this information you’d have not much way of knowing if one of them were, say, 10% below par. In the Lear Jet the EPR gauges are monitored (by the copilot) in the take-off and initial climb, but not much attention is paid to them after that.

Why Faster

One of the major differences between flying with a non-super-charged piston engine and a jet lies in the thrust performance. With the piston engine, the thrust starts at a maximum with the airplane standing still and then declines rather rapidly as the speed increases. This explains why the piston airplane gets off better. At some point the line describing the declining thrust of the piston-propeller power combination crosses the ascending drag line of the aircraft (as the speed increases) and that determines the top speed of the aircraft.

Lear Jet 24
The Lear 24 was the first Lear Jet that really proved to be practical for business travel.

In contrast to having less thrust the faster you go, the jet engine has almost constant thrust the faster you go. At the start of the take-off the thrust is less than that of a comparable piston engine with propeller, but as the airplane accelerates the jet reacts to the increase in ram pressure very markedly. The kick in the power performance comes towards the last of the take-off run. And from there on the drag of the airplane goes on up due to increased speed, but the thrust does not diminish and the airplane’s drag line and the engine’s near horizontal thrust line cross at a much higher speed than is the case with the piston airplane, consequently the jet has a higher top speed.

5 Seconds

Meanwhile a mental note that it takes a jet engine awhile to spin up, consequently from an idle r.p.m. to full power might be a too long time if you got too slow in an approach. This is one of the reasons they like a flat, dragged-in approach, with full flaps and the gear down, well out, so that a reasonable high percentage of power can be used. Tied to this is the fact that you don’t really get much thrust until you go past about 80% r.p.m. Or, in other words, about half the thrust available comes in the last 20% of the throttle position. So “adding a little power” when you’re in a lower power range is likely to be mighty little.

En Route

In cruising flight you watch the exhaust temperature gauges to see that your campfire is burning normally and set your power with the throttle and tachometer, much as if you had a fixed pitch prop (which, in a way, is what you have). The tach is scaled in percentages of r.p.m., to get away from large numbers, such as 18,500 r.p.m. wide open. Take-off is with approximately 100% r.p.m. (adjusted as necessary to get the posted EPR), climb is with from 90-98% r.p.m., and cruise is usually with 92% r.p.m. In a descent you seldom use less than a 70% setting. It is very easy to set up any desired % of r.p.m. The tach has a large hand for the big numbers and a small hand and separate scale up in one corner of the face which runs from 0-10. To set 92% power put the big hand on 9 and then go to the small one and put in on 2, all with the throttle.

Woah

While jet aircraft are well streamlined, they aren’t mysteriously so and to understand that they go so fast only because of sheer power all you have to do is reduce power from say, 92% r.p.m. in level flight, to 70% r.p.m. It really leans you forward in the seat. For this reason, surprisingly, the jet is not a slippery thing to get down. The throttle alone is quite a speed brake. But don’t go closing the throttles or opening them too rapidly at high altitude or the fuel metering system will get out of step with the varying mixture requirements and you can get a flame-out.

The Take-Off

The jet’s wing is thin, so as to get low drag at high speed. Then wings operate at higher angles of attack for maximum lift than thicker wings. This explains the high nose attitude and climb attitude of the airplane as you rotate on take-off and then climb out. The take-off in a jet is as much a race to get power, from the increased ram effect on the thrust output of the engine, as it is to get the proper take-off speed, called Vr, or velocity at which to rotate. Vr is calculated for each take-off and it varies according to the weight of the airplane. It is one of those things which it is necessary to be precise about. Rotate too soon and the airplane simply won’t fly nor will it accelerate from there on to flying speed because of the high drag of the wing at the high angle needed for take-off. So there’s just no such thing as pulling one off. You run up to Vr with it level on the runway (no back pressure on the wheel at all) and when you hit Vr, rotate to the climb attitude and it simply goes from right there straight up your climb path, still accelerating. On the other hand, running past Vr before rotating can also lead to trouble because it moves the rotation point so far down the runway and gives such a high initial climb airspeed that the initial climb path can be pretty flat. Precision, then. Get to Vr and Go. Not before. Not afterward. Right on Vr. Do this and you’ll soon be looking at 6000 f.p.m. on the rate of climb. Take-off flaps of 20° are always used, otherwise you’re not likely to take-off at all. Precision, then, also in the check list phase.

The Law

The Lear Jet is certificated under FAR Part 25, which means that not only will it really go on one engine but a pilot will be in violation if he flies it under any conditions under which it won’t go. This is the Part under which the airlines operate and it involves the Balanced Runway concept. For each take-off a V1 speed is computed. What they’re thinking about is really length, but you can’t measure distance in an airplane as easily as speed. So V1 is used. It means a speed to which you can run on this take-off, considering weight of the airplane, temperature (which affects jet engine thrust greatly), pressure altitude, wind, and 1) either shut an engine off and stop in the remaining runway available, or 2) let it run on up to Vr on the other engine and go out with 35’ over the end of the runway. If the runway is not long enough to meet these requirements then you’ve got to lighten your load until it is, or wait for a lower temperature, or more wind. It is, you might say, against the law to operate otherwise in an airplane carrying a Part 25 Certification and handbook to match.

The Back Side

Lear 24 cockpit
An advanced cockpit, for the time…

The need for precise speed control in the jets comes out in another of those variations. The jet’s thin wing flies at such high angles at low speed and the drag is so high that the airplane just hasn’t enough power even to fly level in these extreme situations. At the low airspeeds the jet engine has lost its ram benefits so it is at a disadvantage. This isn’t a stall situation, but something which comes well before a stall: you’re too slow and hold your attitude and gun it and keep on going down. In these situations you’d better have some altitude to trade for speed, say a thousand feet or so, and think in terms of nosing down because power alone isn’t going to do anything for you. In the piston airplane, in contrast, too slow and gunning it increases the airflow of the propeller slipstream over the wing, thus creating more lift. Also, at the low airplane speed the propeller thrust of the piston engine is greater than at any higher speed. Neither of these things are working for you when in too slow flight you “gun” a jet. So you fly a jet like you do a glider, you nose down for More. But you need room, extra room in which to nose down, so the premium goes to maintaining a speed which won’t let you get into this jam. There is a back-up for the airspeed indicator and your arithmetic on this in the form of an angle of attack indicator on the panel, near the top in easy view. It has no numbers―just three large pie-shaped segments, green, yellow, red, so it is easy to tell at a glance whether you are as far in the green as you should be. The needle is always in the green when the proper climb and approach reference speeds are used.

High or Else

Another of those variations which has to be understood thoroughly concerns range. All the old ideas have to go pretty well out the window. Flying at maximum L/D ratio speed, leaning, using relatively high m.p. and low r.p.m. either don’t exist or don’t work as well on the jet. The overriding consideration is not airplane drag but engine efficiency, and there’s no way to lean—that’s handled automatically all the time by the fuel metering system.

To get anywhere in a jet you’ve got to spend as little time as possible below 35-40,000’. Up there is where the only favorable m.p.g. figures are obtainable. Or miles per pound, rather. It’s a machine whose element is thin air (and high speed). Even on a trip as short as 250 miles it pays to go right on up, even though you’re going to fly level only a few minutes before starting down. In case of a critical fuel situation, the procedure would be to stay high until almost where you’re going, then extend the spoilers and come down fast and steep (the spoilers permit descents of as much as 6,000 f.p.m.). This would keep the time at low altitude at a minimum. In normal operating, descents are started from 100 to 120 miles out as this fits into traffic control better, but it isn’t the way to get down on the least fuel.

This thing of flying high, always high, doesn’t sink in immediately. Looking at a few consumption figures helps the process though. It takes 10 lbs per minute to taxi on one engine. In a properly managed climb to 41,000’ about 800 lbs of fuel are used. Normal, as distinguished from maximum permissible cruise at 41,000’, calls for around 1150 lbs/hr for both engines, flying at Mach .77 and with 92% r.p.m., or at around 508 m.p.h. An odd figure: taxying on one engine its fuel flow indicator reads 550-600 lbs/hr, so you might say these engines require the same fuel for cruising at 41,000’ as they do to taxy!

Dropping down to 20,000’ and holding a Mach .77 cruise, the fuel consumption would go from your 1100 at 41,000 to around 1700 lbs/hr, so you can’t afford 20,000 even. But what if you had to stay low? Or need more convincing. Holding at 5,000’, throttled way back, the least you could stay up on would be 1600 lbs/hr. Cruising at 5000 would require 2000 lbs/hr, so if you took off and flew at 5000 you’d go only a bit over half as far as you’d go if you went on up to 41,000’ and 1100 lbs/hr. So, you learn to Think High.

The jets have such an abundance of power at high speed that they can fly into the sound barrier in level flight. As the speed of sound is approached shock waves begin to form at the leading edge of the wing and tail surfaces and just a little faster a standing wave can form about two-thirds of the way back on the wing and next thing you know your airplane is shaking like a wet dog and is almost uncontrollable due to heavy control forces. This situation introduces the term Mach Number, which is the speed of sound at any given temperature. At sea level Mach 1 is about 750 m.p.h. At 40,000’ it is about 600 m.p.h. Mach number is still an airspeed, and you get your reading on it off the airspeed indicator. In a sense Mach number is just a speed limit, one which varies. In the Lear Jet you start off climbing with, say, 250 kts. indicated. There’s a rim over on the left side of the airspeed face which is movable and has Mach numbers printed on it, with a special mark at .82, which is as close as you want to fly the Lear Jet (each jet has a slightly different Mach limit) to Mach 1. As you climb up with your airspeed needle on 250 the Mach scale moves slowly counter clockwise, and finally at about 20,000 feet .7 is almost under the end of the airspeed needle. From there on you climb at Mach .7 and since the temperature and consequently the speed of sound is decreasing as you go up you are observing a lowering speed limit and flying at gradually reduced airspeeds in your climb. When you level off you have to reduce power immediately to about 92% r.p.m. otherwise you’ll bump into the Mach .82 speed limit and get a warning horn. Normal cruise is at Mach .77.

Buffet Corner

Pilots by Lear
Going for a ride in a brand new jet? Sign them up.

In the early days of the large airline jets (way back, 10 years ago!) they got into trouble in what might be called Buffet Corner. Two things happen as you go up: 1) the true airspeed needs to be decreased to keep below the limiting Mach number for the airplane, and 2) the stall speed is creeping up behind you. With the big ones heavily loaded the pilots would sometime climb them up to an altitude, around 38,000’, and level off to cruise at their limiting Mach number without realizing that they were also flying quite near their stall speed. If the airplane hit a bump, resulting in a stall buffet, they’d think they were too slow and speed up and hit the shock wave effect, and nose down even more in an effort to get out of what they thought was a stall. Or they might get a little too fast and in correctly recognizing the situation slow too much and get into the stall buffet, and slow still more, not recognizing what they’d backed into. The cure was not to go so high when so heavy, and to avoid maneuvering in Buffet Corner. This hasn’t anything to do with a jet’s ceiling. Most any of them will fly much higher than the point at which the line for their limiting Mach number crosses the line indicating their stall speed. With the smaller jets, with their better power/weight ratios than the big ones have, their operational ceiling, due to pressurization limits selected, is usually well below an altitude at which they’d find the Buffet Corner. In the Lear Jet, for instance, Buffet Corner would be at around 54,000’. The operational ceiling is 45,000’ because that is as high as they can maintain a cabin pressure of 10,000’ with the 9.2 lbs. per sq. in. pressure differential which the cabin is designed for.

The Great Out-of-doors

In flying so much at around 40,000’ the pilot needs to know the facts of life about his environmental situation up there. Before take-off in the Lear Jet you set the altitude you’re going to and the barometric pressure into the cabin control system, and from there on everything is automatic. You don’t know you’ve left the ground at first, for up to 22,800’ the cabin stays at sea level pressure. By 30,000’ it has gone to 3000’ altitude, and at 41,000’ it holds at 7000’. All the comforts of home, then. Even the cabin temperature remains constant. But nature isn’t far away―just the thickness of a thin metal skin reinforced with a series of steel banks and a few inches of insulating material. At 40,000’ the OAT is likely to be around—60°F and there’s not enough oxygen in the air for a person to retain consciousness for more than a few seconds. For this, precautions and procedures. Cabin pressurization will remain normal on one engine, either one. At 25,000’ going up, the pilot hangs his oxygen mask around his neck, operation of which he’s included in his check list originally. At 25,000’ with a depressurization he could take his time about getting down, but at 40,000’ he’d just have time to slap on his mask, flip the spoiler switch, put the gear down, and enter a steep descent. In all, it might take him two minutes to get down to 25,000 and that is about as long as the emergency oxygen system would make it possible to retain consciousness at 40,000’. At any time the cabin altitude reaches 10,000’ a warning horn sounds, and at 14,000’ cabin altitude airline-type hand-held oxygen masks fall out of the ceiling in front of the passengers. All they need to know is to put the cup over their nose and mouth and pull a lanyard which falls down the mask, which turns the oxygen flow on.

Sleepy Time

The afternoon program reflected the fact that the Jet Flight Familiarization Course is a compression of a week’s course into one day, a course designed for someone who is going to get a rating on the airplane and be competent as Pilot in Command. A big part of the week’s ground school is consumed in getting a full understanding of structures, the hydraulic systems, flight controls, fuel system, electrical system, and instrumentation. Consequently, in the compression, these subjects occupied the same percentage of the time available, and this was the heavy going. Suffice to say, while much of the concentrated technical data presented was not usable for one who was not going to get checked out but was going to get just one crack at a take-off, climb, cruise, descend, and land profile, it did serve to bring into sharp focus how much there is to know about the machine and how important it would be to know all there is to know about its mechanisms.

Better Know

For instance, the Environmental System, new to most pilots, would need to be understood fully―every switch, every indicator, every warning signal, every alternate arrangement, every circuit breaker, fast and without thinking. Environmental System? It includes the refrigeration system, the heating system, the temperature control system which has both automatic and manual mode, the windshield defog system, which includes a windshield alcohol backup system for the outside hot air system, the pressurization system with its indicator and automatic and also manual control, and, finally, the oxygen system. Why is it important to really know every detail, and be able to do things “with your eyes shut?” One ex-Lear pilot, careless with his checklist, took off with the pressurization switch on Manual. At 5000’ he had the cabin about 5000’ below sea level, and realizing something was amiss opened an emergency dump valve, resulting in an unfriendly attitude on the part of the then President of Lear Jet, who was aboard.

and so on . . .

Lear Jet 24 cockpit
The sloped nose sometimes caused pilots to land in a very high attitude.

Then, there’s the electrical system, with both AC and DC and a primary and secondary inverter with a jillion switches, the fuel transfer system with all sorts of pumps and valves, the hydraulic system—and so on. A week might be too short a time for all of this for a lot of pilots. But through even the brief form the image of the airplane grew and grew. There’s a back-up for almost everything (with appropriate switch and procedure). For instance, the horizontal stabilizer is normally operated by an electric motor controlled by a four-way button on top of the left control wheel horn (the button moves sidewise to trim laterally). If this system fails there is another motor with an independent wiring system with its separate switch which can be used. And so on, through a back-up hydraulic system for flap control, a separate battery to power the second back-up artificial horizon in front of the pilot. In the end you wonder how it is possible to get into this small airplane, as jets go, everything it has to have and have enough room and weight allowance left for a reasonable amount of fuel and any payload at all. But it has all these things and flies twice as high and twice as fast and climbs three times as fast as the most advanced piston airplanes. One can only look up to it, literally and figuratively.

New

Ground school wound up with a session on high altitude weather, how to check it, and the procedures to be used in dealing with it. It is different, all right. The explanation begins with the regions of the atmosphere. First there’s the troposphere, which extends up to about 33,000’ and contains most of the moisture and weather. This is the one we all know about, or at least get our weather experience from. The next region is the tropopause, which may top out at anywhere from 64,000’ to as low as 28,000’, depending on the latitude and time of year. In this region the temperature remains constant as you go on up. One of the jet pilot’s first weather inquiries is “Where’s the trop?” He wants to know that because this is the region in which the jet stream meanders, with its winds of from 50 to 300 kts, with more turbulence above its core than below, and more on its north side than south. It is located, usually, by looking at the 300 mb chart (30,000’ level approximately). If the top of the trop is low enough a westbound pilot may be able to fly in the third layer, the stratosphere, where the winds are moderate, the air smooth, and there is no weather except an occasional isolated thunderhead which coasted on up into it. And so on, through the clear air turbulence associated with the jet stream, haze layers aloft which are not visible from the ground but which put you on instruments and out of which you can’t see the ground, the constant pressure charts (on which, something new, are Isotachs: dotted lines along which lie points of equal wind speed), and Constant Pressure Prog charts.

Der Tag

The day on which you first fly a 500 m.p.h. plus airplane you’re likely to wake up early, and, for instance, start studying the large blueprint you have of the instrument panel layout. But there wasn’t too much time as the after-breakfast pick-up time for Flight 1, to which we’d been assigned, was 6:45. Bob Berry, ground and flight instructor and ex-military jet pilot, who would be in charge of this flight had gotten up even earlier, for on arrival at the briefing room he already had projected on the screen the flight log for the exercise: Wichita-Omaha. Switch pilots on the ground there. Omaha-Springfield, Mo. Coffee and switch pilots again. Then Wichita. The ground speed on each leg, fuel consumption for taxying, take-off and climb, and in cruise and descent for each leg had been carefully computed. He also had a copy of the 300 m.b. chart on which he’d based his plan. Balanced field length for the first take-off would be 4600’.

He also carried the three of us through a walk-around inspection of the airplane, and it is a thorough one. Condition of leading edges, tires, all cowling fasteners, fuel caps and fuel vents (near the tail), static vents, a look into both ends of the engines for any evidence of blade damage from any ingested bolts and nuts with which most any airport abounds, control surface conditions, and so on. Including fuel sump drains and a final check that the oxygen bottle was turned on.

The question of who would fly what leg came up and during all the bowing we suggested that the holder of lowest license number pick the leg he wanted, and so on. Jack Chastain, who flies a Twin Beech for Petrolite Corp., in St. Louis beamed in agreement, but he didn’t get the second leg like he wanted because he was born, aeronautically, just a bit too late. So he took the first leg, and Armando Sanchez, of Flight Proficiency at Ft. Worth, the third. We wanted the second leg to see what the first man up had trouble with. The third leg would have been even better from this standpoint, but we were eager. Also aboard, as an observer, was Arnold Lewis of The Wichita Eagle. He flies publisher Marcellus Murdock’s Baron occasionally.

Ten Minutes

Jack got the full treatment on the checklist, as this was the first flight of the day, and it is really something. A pilot could fly an airplane like this and take care of maybe one or two discrepancies without too much trouble, but that is about all he could spare time for. So it becomes necessary to check that everything is working and all the switches are set properly. It goes on and on, and with background music, for there’s one tone for the gear up warning, another for the stall warner (which also shakes the stick and puts a bit of forward pressure on it), still another for the cabin pressurization warning, and a fourth for something else. Then all warning systems and lights have to be checked, fuel pump operation, all twelve items on the backlighted annunciator panel such as left engine ice, right engine ice, and unaccustomed items like hydraulic pressure and emergency air pressure. All trim motors and back up motors are checked, trim set, cabin climate control indicators and controls set and tested, and so on again. Even operation of the small generator down in the main-wheel hubs which is part of the anti-skid braking system is checked!

Round One

Lear Jet spoiler
To go down and slow down, spoilers help a lot.

Jack finally taxied out and took off on an IFR flight plan to Omaha and 45 minutes from fire-up we were on the ground there, 220 n. about. That doesn’t sound like 500 m.p.h. but it is the old story of speed not coming into its own except in the long stretches. Jack really laid it on at Omaha, this being about his fifth landing in a Lear Jet. His company has looked at several jets and decided not to do anything for the time being. Jack’s preference seems to be the Lear jet. When he asked his boss for the $350 for the Familiarization course the first answer was no, that all he’d do would be to go down to Wichita and come back drooling more than ever. But he was finally given permission to do so, and he had a good start on it by the time he started climbing out of the left seat at Omaha.

Easy Start

Since this stop was little more than an elongated touch & go, our check list was an abbreviated one. The active being only a short distance away, Bob told us to start up the engine which Jack had shut down taxying in (all taxying is done with only one engine, to save fuel). It is incredible how nicely those engines start. The starter switch is simply moved to the start position, the r.p.m. gauge starts moving up, and when it reaches about 6% r.p.m. the throttle is moved forward to the idle detent. This triggers the fuel injection and ignition system. The next thing to watch, as the r.p.m. builds slowly on up, is the exhaust temperature gauge. With ignition it jumps rapidly through 2, 3, 4, and on up to about 600° where it stabilizes. When the r.p.m. reaches about 15% the starter switch is moved to the off position and from there on you’re ready to go, done by moving the throttle over to the right from behind the idle detent position and advancing the throttle as needed. If the exhaust temperature goes on up during the starting cycle, to around 900° you shut the starter off and put the throttle in cut-off position. This is called a hot start, i.e. it is too hot for the engine to stand. It is caused sometimes by starting up with the airplane tailed into a good wind, but usually the cause is a weak battery. Even though the engine is in process of starting as the r.p.m. is increasing from 6% to 15% it isn’t yet developing enough power to do all of its own compressing, so the services of the starter must continue during this acceleration. If the battery is too weak for the starter to contribute its necessary part then the mixture gets all off and the temperatures go beyond the limits of the metal used in the turbine and other parts. But our start involved none of this. Otherwise a battery cart might have been needed, except in this case the other engine never had been shut down so we already had extra power.

Taxying in the Lear Jet is done with the rudder pedals, but in name only because they aren’t hooked to the nose wheel and there’s no “slip-stream” on the rudder. You have to remember to hold a small button on the left control wheel horn down. That turns on the power steering and makes your rudder pedals work for steering purposes. We needed a short turn at first. To turn short it is necessary to reach forward to a toggle switch on the instrument panel and hold it down. With that one the turn can be short radius indeed and the boost is too quick to do ordinary taxying with it. So after the short part of the turn you go back to the regular more docile “power steering” button.

T/O Data Card

By the time we got to the runway and not quite stopped Bob had the IFR clearance to Springfield, and at some point had put a revised Take Off Data Card on a clip on the instrument panel. Jack Chastain had used a V1 of 120 kts, Vr of 132, and V2 of 131 at Wichita. We were now some 1200 lbs. lighter, so our speeds had been revised to V1 104, Vr 119, V2 120. The temp was shown as 60° and EPR 2.25

Being cleared for an immediate take-off we kept rolling and started moving up the throttles as soon as it was pointing down the runway. We remember asking Bob if there was any way of over-revving and he said no and that he’d take care of the power as soon as we were off. We’re not sure, but think just before rotation he throttled back a bit to keep the EPR at 2.25

As you start your roll it is necessary to keep the steering button on the wheel down until you get to about 60 kts, otherwise you can’t keep it straight as the rudder is not effective until then. Meanwhile Bob had shut off the yaw damper, saying that he’d turn it back on as soon as we were airborne.

Real Action

When you’re watching, either from the right front seat as we did once at Grand Rapids with Ed McCready flying, or from the cabin, the take-off in the Lear Jet is a very spirited but at the same time slightly long drawn out affair. When you’re doing it yourself, though, it all seems mighty quick. Before we knew it we had 60 (everything is in knots) and had to let the steering button up. Soon after that we got a glimpse of 100 on the airspeed. Right after that Bob called out Vr and we rotated. It doesn’t lift off in the usual sense but just starts going where it’s pointed, which is really steeply up. It is not difficult to keep the airplane straight in the take-off run, and you’ve hardly gotten the gear up when you’re going through 200 kts. The flaps are raised at 1500’, power is reduced to 90% r.p.m., and 200 kts. held to 6000’. At 6000 you go to 95% r.p.m. and hold 250 kts. At 10,000’ the r.p.m. is increased to 98% and the speed to 300 kts, and this is held until March .7 gets under the tip of the airspeed needle and then you keep it at Mach .7 the rest of the way up. While we raised the gear and flaps and made the power and speed adjustments indicated, and found it surprisingly easy to do these things, don’t get the impression that this was all on the casual side. Being a bit light we were climbing nearly 7,000 f.p.m. during this time! Also on the way we had begun to experiment timidly with the nose-up nose-down trim button, which is really a primary flight control because you just don’t fly this with the elevators, the control forces are too high for precise control.

So Far, So Good

Meanwhile, during the minute and a half to 10,000’, Omaha departure control had pawned us off on Chicago Center. Shortly Chicago passed us on to Kansas City Center. Bob was doing the talking and negotiating and we were concentrating on attitude and airspeed and 147°. Actually we were in no trouble and not really under a lot of pressure. It is easier than most airplanes to keep on a desired airspeed, and it is also easier to keep on a heading. With the yaw damper on, whatever it has in the way of Dutch roll characteristics is converted largely into roll, but it is quite slow to turn any with a wing down moderately. At one point we were wondering if its slowness to change heading in a shallow bank was not caused by the yaw damper, but that isn’t so. The yaw damper just senses and stops high rates of yaw. Low rates, as in a turn, it doesn’t react to at all. So it is not the same thing as P/C at all. It makes no effort to level a wing in a turn.

At 33,000’ we got confused by the altimeter hands and thought we were going through 23,000. It was at about this point that Bob asked if we wanted to see what the last 2% r.p.m. would do for climb, and with that he moved the % from 98 to 100. It really gave it a strong push, adding another 1000 f.p.m. to the climb. By this time we had the Mach .7 mark intercept the tip of the airspeed needle and were holding .7.

Meanwhile something else easy was developing. At the speed at which this airplane flies, even in a climb, drift correction angles are small, so it being so easy to hold on a heading it is also easy to keep the omni needle centered. And if a cut is needed, it shouldn’t be more than a couple of degrees, otherwise you’re sure to run through.

Initiation

First thing we knew we were at 41,000’ and with the airplane levelled (all this is done entirely by instruments) and trimmed and with Bob putting the % r.p.m. up a bit past 92% he announced that we were now all here and thereby 8.8 Club members, since we were flying 8 miles high at .8 the speed of sound.

Down, Now?

Only a few minutes after that the omni changed to From over Kansas City omni, Bob reported, and in another minute or so got a clearance to start our descent for Springfield. Descent? We hadn’t quite gotten squared away yet on holding altitude properly in cruising flight. But down we started. 80% r.p.m. About 3000 f.p.m. down. The airspeed needle got up to about the 250 mark at around 25,000’ and we cast off from the Mach .7 we’d been holding down to there. Since we had a 75 kt. tailwind component our starting down 130 miles out wasn’t quite soon enough, so Bob suggested at one point that we have a go at the spoilers. With our 250 kts. they gave us about 7000 f.p.m. down and not really very much shake.

By the time we neared Springfield omni we were down to enroute minimum and they cleared us for a back course ILS. This is easy with the PN-101 (hooked in this case to Wilcox omnis, with a Bayside standby) as you simply set the bug on the front course heading and correct towards the needle as you would in a front course approach.

Our clearance was also for a circling approach, so after crossing the field at 500’ with 150 kts. and 20° flaps we made a square pattern using the tics on the flat faced DG to put the landing runway heading under. The Lear is also easy in speed control at the pattern speeds, so we were soon around and on final, gear down and were calling for full flaps, and had it pretty well trimmed and stabilized at our computed threshold reference speed of 123 kts plus 5 for half the gust velocity, with about 80% r.p.m.

On the Canvas

Then our trouble started, and where we’d expected it, what with nearly 1000 lbs of fuel out there in each tip tank. We never did get it stopped rolling from side to side, all, of course, from over controlling. The trick is, right after using some aileron to pick a wing up, you center the wheel and let the wing coast up and be ready to use a bit of opposite aileron if need be to stop the wing at level. But there’s a difference in knowing and doing, and all we had time to do was know.

The final difficulty was in finding the ground. The nose cone slopes down so steeply that you get the feeling that you’re surely going to land nosewheel-first unless you get the nose pointed up at least a little bit. Result, almost everybody at first flares too high and thinks they are in a level attitude when in fact they are making a quite nose-up approach. Bob kept telling us, “Get it lower. Get it lower.” We’re not sure exactly what happened or what part Bob played, but we landed farther along than we expected, never did get the lateral oscillation stopped, landed, not too hard, on the right main dual-wheel, and that fine gear took care of the rest. Those wonderful brakes―no matter how hard you push the wheels won’t skid. The small generator and its computer down in the hub reduce the pressure in the brake cylinder as necessary to keep the wheel braking but not coming to a stop and sliding.

What Happened?

The time/distance/fuel profile of our flight had been 12 minutes climbing to 41,000’, level flight at 41,000’ 5 minutes, descent 21 minutes, total 38 minutes. We had climbed for 80 miles, flown level for 45, and descended for 130 miles, total distance 255 n. The fuel: 800 lbs to climb to 41,000’, 115 lbs to fly level, 300 lbs to get down, total 1215 lbs for the 38 minutes and 255 miles. The slow part of the flight seemed to be the descent, which, of course, it was, at least in minutes.

From this you can see, since the level flight part was so short, how it would be on a long flight at 41,000’. Starting with everything full, i.e. 1200 lbs in each wing, 1160 lbs in each tip tank, and 1375 lbs. in the two tanks in the back end of the fuselage, with a short taxy and prompt clearance, you’d get off with about 6,000 lbs of fuel. Since the up and down part, judging from this flight, would require 1215 lbs, that would leave you 4,785 lbs to use for cruising, holding, and alternate. Or in other words, after 3 hours level at 41,000 you’d like to start down in order to keep a little money in the bank. Used to thinking in terms of 7 hours’ fuel this sounds a bit short to us, but in miles it is considerably more range than we’re used to, so the thing to do is to think in terms of what really counts, which, of course, is the miles.

Really Impressive

After Armando Sanchez made his landing at Wichita, which we thought a little wilder than ours (but our newspaper friend Lewis said not), Bob took it around once from the right side to demonstrate an ILS with the autopilot and coupler, a missed approach with an engine out, and a maximum braking landing. The autopilot part we’ll skip as it is a little embarrassing what these computer can do. But on the other items a lot could be said. Especially about FAR Part 25. The Lear Jet will sure sell you on that one. Bob crossed the middle marker with 200’ and held his Vt (Velocity, threshold) speed right on down to where it was time to start his flare. This was with only one engine running, at about 5% more than normal r.p.m. Applying full power to the operating engine (the other one was idling) he “rotated,” retracted the gear, raised the flaps to 20° and at 150 kts put the flaps up. From the time he started his go-round until he had 2000 f.p.m. rate of climb is less than it takes to tell it. You’d never worry about this one going on one engine.

In his landing, he got stabilized in a flat approach, gear and flaps down, fairly high power and the airspeed right on the computed Vt of 120 kts. plus 5 for half the gust velocity. Even in demonstrating a short field landing no compromise is ever made on speeds. Mainly he just had it, not any slower than normal, but with the numbers on the runway coming right at him, i.e. moving neither higher or lower on the windshield. The touchdown, preceded by only a slight increase in the approach attitude and followed by spoilers up once on the ground, was in the first 100’ of the runway, which was impressive enough, but you should see what anti-skid brakes do for this airplane. It is almost as if the tires were digging into the concrete―a powerful, smooth stop. He made the first turn-off on 19, which scales on the Jeppesen approach plate about 1800’. Wind was about 20 kts, weight about 10,000 lbs.

Sold

In all, we were greatly enthused about our experience, because we felt that within the usual 10-hour check-out period we could learn to fly this airplane. We might need to go through the week’s ground school twice, but not the flying part. A lot of it is much easier than we’d expected. The lateral control difficulty we had expected, but it has a way of disappearing all of a sudden with a little practice. The landing should be mainly a question of getting used to the optical illusion that down-slanting nose gives us first.

Like most people who fly privately to-day, we assume that we will never have a jet, in fact would be willing to bet on it. Still, in a Turbo Twin Comanche, on only 15 g.p.h., we can cruise blithely along at three times the altitude and three times the speed our Cardinal had. Not to mention having an extra engine. Is it reasonable to assume that this is the end point of progress in general aviation aircraft performance? No. On the next go-round the factor may not be three, but there are surely many, many new pilots to-day who, as improbably as it may seem, will wind up flying twice as high and twice as fast as they do now. And it may come faster than before, because the twice as high and twice as fast is already in production whereas it hadn’t even been invented before.

As mentioned at first, the purpose of the Jet Flight Familiarization Course was to sell jet flying, not Lear Jets. In the lectures they mentioned Lear Jet only rarely as compared to our many interpretative references. But as you can tell, they’ve really got themselves a show horse in the Model 24. And it’s sure worth $350 to ride it around the ring once. Better think about it. Classes start every Tuesday, early.

8 Comments

  • Wow, a trip down memory lane.

    I flew many times as an experimentor in NASA 701, the Learjet shown in the photo. Back in the 1970s NASA Ames Research Center in the San Francisco bay area operated 2 Learjets, 701 and 705. They were called platform aircraft, which were not flight test vehicles but they carried instruments and experiments. My recollection is that 705 had a special window and it was mostly used to fly astronomy telescopes at very high altitudes. 701 was more the general purpose aircraft and the one I flew in most of the time.

    My own experiments as a PhD student had to do with fluid mechanics studies in reduced gravity. I also performed experiments for other folks who either weren’t medically qualified to fly or didn’t want to do it. I jumped at any chance to fly and have logged thousands of “0g” parabolas in the NASA Learjets as well as the infamous “Vomit Comet”. More fun than you should be allowed to have with your clothes on.

    The NASA crews were outstanding, all were former military and test pilots. They absolutely loved to fly the types of experiments that I did because they got to really fly the airplane as opposed to the astronomy missions where their job was to fly as high and smoothly as possible.

    So many stories, here’s 2 quickies, I believe the statute of limitations is long since passed. On one flight the crew had a bet that they could do an aileron roll while flying the parabolic arc required for 0g. So the co-pilot laid down on the floor, all the seats were out except the rear bench where I was sitting, and the idea was to go ballistic and then roll the aircraft around the co-pilot. They did it almost perfectly. I have it on video but no idea where the film is.

    Another time a new pilot in training managed to overshoot the entry to each parabola and pull some negative g. No big deal except it threw hydraulic oil out the tank vents for both engines and both pumps failed. We ended up with no hydraulics which meant no flaps or brakes. No worries, they set it down perfectly on the long runway at Moffett Field then kept the nose off the ground for as long as possible, turned off at the NASA taxiway, and rolled to a stop right in front of the NASA hangar. The whole tail of the aircraft was covered in hydraulic oil.

    Then there was the time the pilot decided to do a roll right after taking off as we were turning to depart. That earned a reprimand since too many people saw it.

    OK, I’ll shut up now but damn, those were good times.

  • What a great story. Very much enjoyed. I once flew with an old timer that was around when the 24 was first introduced and he had some amazing stories to tell about his time flying it and some other early corporate jets. He helped me get checked out in a new King Air before he passed away. Good stuff.

  • The change in metrics is phenomenal! What one has to understand about systems, speeds, and other physics verses a prop are mind boggling. Totally different! I found it all fascinating. I’ll only be a little Cessna driver the rest of my days, but have even more appreciation for this type of aircraft and those aviators who fly them. The average person really has no clue. Thanks for sharing this article again.

  • Bruce Webbon, the video rolling around the guy in zero g’s would be incredible to see. Hope you are able to find it and post it. Sounds like way too much fun. LOL.

    • Unfortunately those Learjet flights were done back in the mid-70s, long before digital video. The film I mentioned was from a small movie camera that was hard mounted looking forward in the cabin. One of my experiments was mounted on a pallet that was released from a cradle on the floor so it would free float during a parabola. That would reduce the g level on the experiment by about 2 orders of magnitude. I would then get a call from the crew to replace it in the cradle by hand before they started the pullout. That was a bit of a chore since it weighed about 125 lbs. NASA and the space program were a lot more wild and wooly back then. Safety was always a concern but we depended a lot more on competence and common sense than on written rules and procedures.

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