Project Briefing -- The Air Scout Copyright 1999 by Doyle Hunt huntdoyl@smtp.lmn.usace.army.mil Disclaimer: The views expressed herein are those of the author, and do not necessarily reflect those of the publishers, authors, or players of The Morrow Project. The information herein, while based upon real-life equipment, should NOT be used for the purpose of real-life aviation! Do NOT try this at home! Credit Where It's Due: Auto-gyros are rather uncommon in real life, and information about them is even rarer. A significant part of this document is adapted from the article "Learning to Fly a Gyroplane" by J. Patrick O'Leary, published in the March 1997 issue of Kitplanes magazine. This document you're (hopefully) reading is intended as not-for-profit background material for use by players of the Morrow Project role-playing game, and is not intended as a challenge to Mr. O'Leary's copyright for his original article, despite the fact that the information gleaned from his article is used without his permission and without payment. Technical Data Correction This article does not include the technical data on the Air Scout which was published in the game manual (TM 1-1). However, I will note here one discrepancy in the published data. In the Third Edition of the manual, the tabular data on the Air Scout lists the landing gear as "fixed skids, with inflatable float pads" (paraphrased, since I don't have access to my manual as I write this). This description is incorrect. As stated by Kevin Dockery, the landing gear of the Air Scout consists of a fixed (non-retractable) tricycle landing gear, as on a small airplane. The various drawings of the Air Scout show the correct landing gear configuration. A Mechanical Overview of the Air Scout The Air Scout is the Morrow Project's most common air asset. It is a two-seat auto-gyro with fixed landing gear, designed to be broken down into six theoretically man-portable parts for storage and ground transport. The six subassemblies are as follows: 1. Cockpit 2. Tail Boom 3. Tail Assembly 4. Power Plant 5. Left "Wing" 6. Right "Wing" In actual practice, it's a little bit more complex. The rotors themselves must be removed from the rotor hub, increasing the total number of separate parts to eight. The pusher propeller should also be removed for storage, but it's not strictly essential. Landing gear may be removed as well, but again is not essential. If the landing gear is removed, both rear wheels are connected to a single strut, which flexes like a leaf spring. Some of the parts have a very odd shape, which makes carrying them rather difficult. For example, the cockpit section is approximately seven feet long, two feet wide, and three feet tall, not counting the forward landing gear. If someone is to carry it, probably the best way would be to remove the canopy, and carry the two pieces upside down, overhead, rather like portaging a canoe. One person could carry the canopy, but two would be required for the cockpit "tub", because the seat location makes it difficult to balance the load on one man's shoulders. Since the Air Scout doesn't have to be carried very far, only from its storage site to its launch-return site, that's not a particular problem, but be advised that assembly is hardly a one-man job in any event. Actual assembly is rather straightforward. Begin with the tail boom and the cockpit sections. These are bolted together with interrupted- thread bolts, meaning that it only takes a one-half turn of each bolt to tightly secure it in place. Because of the configuration of these parts, it is necessary to have someone hold the tail boom up off the ground at the rear while it rests on its two landing gear at the front. Another person has to hold the rear end of the cockpit in line with the tail boom, while the front end of it rests on its single landing gear. A third person then bolts the two subassemblies together. Alternately, the two subassemblies may use any kind of available cribbing to block it into place, allowing a single person to perform this stage, but with some increase in the time required. Once these two modules are assembled, the control lines for the rudder and landing gear brakes are connected at the rear of the cockpit. The tail assembly us added next, including final linkup of the rudder control lines. Unlike an airplane, there is no elevator control, only a fixed horizontal stabilizer. The power plant assembly is then lifted into place and bolted down. Access panels on the sides of this module allow one to reach in to connect the rotor control lines and the engine controls. Be advised that it is difficult for one man to perform this part of the assembly process. This section includes the fusion pack and a high-torque electric motor to turn the propeller, with a power takeoff for the main rotor, and is actually even heavier than the cockpit section, although somewhat more compact. Lifting it into place and aligning it properly is best handled as a two-man job. The access panels also allow the pilot to reach lubrication and inspection points when performing maintenance. At this point, the propeller and main rotor blades are attached. The propeller simply slides into place, with a key-way on the shaft to keep it from slipping, and a hub is screwed down over it. The hub is threaded so that the motion of the propeller tends to tighten the hub. The rotor blades themselves are bolted on, with a total of seven bolts per rotor. These bolts are not interrupted screw types, but instead are fully threaded, using crown nuts. The ends of the bolts are drilled to accept cotter pins, which interlock with the crown nuts to keep them from coming loose. The wings are attached last. The term "wings" is actually a misnomer. Although they do have a somewhat aerodynamic shape, the provide very little lift, and actually function more as weapons planks. The Air Scout will fly perfectly well without them, at the cost of going unarmed. There are two electrical connections for each wing, one for the Stoner's electrical trigger assembly, and one for the missile ignition/release. These have differently-shaped plugs, so that one can't accidentally connect the missiles to the machine gun trigger. Disassembly is basically a reverse of the process. Air-mobile Sardines The cockpit of the Air Scout is not the most comfortable of accommodations. Small air crewmen are definitely preferred! The pilot, who sits in the forward seat, as a total volume of four feet long, two feet wide, and two feet tall in which to shoehorn himself. He shares this space with the control panel. Luckily the controls of an auto-gyro don't require a lot of movement, because there's not a whole lot of space between the pilot's knees for side-to-side movement of the stick. He obviously sits in a semi-reclined position, a lot like an F-16 fighter pilot. The observer is in no better shape. His space is three feet long, three feet tall, and two feet wide, and he has the same controls, except he has the radio in his panel while the pilot has the Autonav. He sits a bit more upright than the pilot, and has to, in order to see directly forward over the pilot's head. In both cases, it sounds like the crew are squeezed in pretty tightly, and they are. But for comparison purposes, the rear seat occupant has about as much room as the pilot of a Cessna 162. Balance is an important criterion for loading an Air Scout. If only one person will be aboard, he has to use the front seat. The occupant of the rear seat, being closer to the center of gravity, has less effect on balance. The cockpit is hinged to one side, and in order to open or close it while someone is aboard, the occupants have to lean toward the right to avoid being clonked on the head by the rim of the canopy. There is absolutely NO accessible internal storage capacity. The occupants shouldn't be able to carry much more than side-arms, and would even have to remove their web gear in order to sit comfortably. If you don't believe me, you try sitting with a canteen poking you in the kidneys for a few hours. Certainly there is no room under the seats. However, that does not mean that there is no internal capacity at all. By folding the rear seat forward, a small storage space becomes accessible in the forward section of the tail boom assembly, directly under the power plant. In the original Air Scout, this was used for fuel tankage, but since a fusion plant doesn't need gasoline, that tankage was removed, but the space remains. This is enough for two people to put their personal issue, assuming they have a reasonable weapon selection. An added benefit is that this storage location is directly below the center of gravity, and has no effect on the craft's balance. However, there is still an upper limit on just how much weight can be carried. I don't have accurate figures for the Air Scout, since I can find no real-world equivalent, but for most auto-gyros of comparable size, six hundred pounds total seems to be an upper limit. For simplicity, assume two people plus their personal and weapons issue will always fit, but nothing else. Control Systems Like most auto-gyros, the Air Scout's controls look like a cross between a helicopter and a normal aircraft, but with a few extras which don't appear on either one. Taking a look at each control in turn will illustrate the differences as well as the similarities. The most obvious control is the cyclic stick. It looks very much like a helicopter's or fighter aircraft's directional control, except for the squeeze lever that looks like a motorcycle or bicycle brake lever, and the switches on top. The controls are laid out for a right-handed pilot. Let's look at the switches first. There are three of them. One is a push-to-talk switch for the radio, and it's located to fall under the pilot's right thumb when the stick is held normally. On the opposite side of the top of the stick, and fitted with a flip-up cover for safety, is the missile firing switch. Using it requires that the pilot move his thumb towards his knuckles (to the right side of the stick) to use, so it requires a deliberate action. The third switch is a trigger for the Stoners, also equipped with a safety. It is placed exactly as a pistol's trigger, where it falls comfortably under the pilot's index finger. One pull of the trigger gives one burst from the Stoners, with both firing at the same time. A light touch can give shorter bursts, but longer bursts are not possible. Like a fighter aircraft, the stick is used for directional control. Move it left to turn left, right to turn right, forward to descend, and backwards to go up. The stick is designed to hold its position when released, and is not center-loaded to return to a neutral position when released. This allows the pilot to let go temporarily (to adjust a radio, for example) without interrupting the maneuver in progress. The rotor, unlike a helicopter's rotor, has a fixed angle of attack relative to the rotor hub. This makes the mechanical linkage much simpler. Also unlike a helicopter, the Air Scout's rotor is angled backwards relative to the fuselage. This is because an auto-gyro generates its lift due to airflow moving UPWARDS through the rotor, and forward movement of the craft is what generates the air flow. Adjustments to the rotor's angle of attack are accomplished by rocking the entire rotor forward or back, moving the rotor mast in proportion to the cyclic stick. A yoke attached to the front of the mast tilts the rotor hub from side to side for banking into a turn. As for that squeeze lever on the cyclic, it controls the power takeoff for the rotor. It's called a pre-rotator. Squeezing the lever engages the rotor clutch, and diverts some power to the rotor to increase its revolutions to the minimum required for takeoff. It is not used at any other time, and is pretty much out of the way when it's not in use. Like an airplane, throttle control is handled by a lever on the control panel. Forward to advance the throttle, backwards to slow the engine. Strictly speaking, for an electric motor it's not really a throttle, but rather a resistor, but the terminology is familiar to pilots and has been retained. Under the pilot's feet are rudder pedals. Again, they work just like on an airplane. Push the left pedal to turn the nose to the left without banking, push the right pedal to turn the nose right. Rudder pedals are not used to turn the aircraft, but instead are used to counteract cross-winds and rotor torque to keep the Air Scout's nose pointed in the direction the plane is flying. On the ground, the rudder pedals also steer the nose gear. Pushing both pedals at once activates the landing gear brakes. To avoid accidental activation of the brakes during takeoff, activation of the brakes requires pushing the pedals down with the toes, causing the pedals to pivot like a car's accelerator pedal. On the left side of the cockpit are two hand cranks that look a lot like window cranks. These are the trim controls. They are used to account for unbalanced loads. Properly trimmed, the Air Scout will hold a level flight profile with the pilot's hands off the stick and feet of the pedals. The control panel includes an air speed gauge, an artificial horizon indicator, radio, and other gauges that any pilot would recognize. There is also a rotor RPM indicator. The radio is a Morrow Project AN/PRC-70, not a normal flight radio. Prewar, an Air Scout pilot would have trouble talking to a normal control tower. Also missing is a transponder. The control panel contains an Autonav, just like any other Morrow Project vehicle, but there are a few quirks to using it. The Autonav is an inertial system, not satellite navigation. It accepts input from the vehicle's own sensors, but it is not as precise as GPS or even LORAN. In the Air Scout, it is tied directly into the airspeed gauge and compass, but as any pilot knows, speed and direction through the air do NOT correspond to ground speed and direction. The longer a flight extends, the farther off the Autonav will be. This is one reason for the 12-hour limit on flight time. Each time the Air Scout lands, the pilot must re-calibrate his position. One hundred fifty years after the Really Big War, calibration of an Autonav after a flight may not even be possible, if the pilot cannot recognize the landmarks shown on the Autonav's maps, and doesn't have a ground-based Autonav to compare it to. Dead reckoning may be more accurate. Flying the Air Scout In the prewar world, according to the Federal Aviation Administration, getting a license to fly an auto-gyro requires a Class 3 medical certificate, passing a written test, 20 hours of flight instruction (15 of which must be in an auto-gyro, 3 hours of cross-country, 3 hours in takeoffs and landings totaling at least ten examples of each, 3 hours of flight test preparation); and 20 hours of solo practice. Someone who already has a private pilot's license at the time only requires 10 hours of solo practice, but still has to meet all of the other requirements. It seems reasonable to assume that the Morrow Project would require similar flight instruction, for safety's sake if nothing else. Takeoffs are relatively simple. The engine is started. The control and rotor locks are released, and the pre-rotator is engaged. That's the official name of the squeeze lever on the cyclic stick. That transmits power to the rotor. In order to generate lift, the Air Scout's rotor has to be turning at least 300 RPM. At first, the pilot must allow some slippage in the pre-rotator clutch, until the rotor reaches about 80 RPM. At that point, the pre-rotator can be fully engaged. Engaging the clutch fully before this point will impart torque to the system which will damage the rotor. When the rotor reaches 100 RPM, the cyclic stick is moved halfway back to its rear stop. At 125 RPM, the cyclic is moved all the way back to its stop. The propeller is still idling at this point, and the pilot is still standing on the brakes. No forward movement. At 150 RPM, the brakes are released, the throttle engaged, and the Air Scout begins to roll forward. Power is added gradually until the rotor reaches 200 RPM. Deliberate forward movement before this point will cause a greater airflow than the rotor can handle, causing it to flex or flap, causing damage not only to the rotor itself, but also to the propeller, since the rotor's up-and-down movement will cause the two to intersect. Once rotor speed increases to 300 RPM, the pre-rotator can be released, but watch to make sure that the rotor speed STAYS above 300 when you do, or you may have to re-engage the pre-rotator and increase the length of you takeoff roll to compensate. This sounds like a lot of work, and it is, but it's all over very quickly because of the Air Scout's slow takeoff speed and short takeoff roll. Any time you have a turning part, you impart torque. In an auto- gyro, torque during takeoff runs is counteracted by the airflow over the rudder (which must be held slightly to one side during the takeoff) and by the landing gear (the nose wheel steers with the rudder). In flight, the rotor is not powered, and so imparts a lot less torque to the aircraft. The small amount of torque due to friction is easily taken care of by the rudder as well. The cyclic is held all the way back during takeoff, and if the pilot isn't careful, the Air Scout will try to take off too soon, and "mush" back onto the runway, or even rock backwards off of its nose wheel and smack the bottom of the tail assembly onto the runway. A small idler wheel added to the bottom of the tail assembly may prevent some damage, but the basic Air Scout doesn't come with one. The Air Scout is allowed to take off by itself, so to speak. This means that once the auto-gyro reaches a speed at which enough lift is generated, it will take off without any additional control input from the pilot. This is about 50 miles per hour for most auto-gyros, and the Air Scout is no exception. This is also the best speed for maximum rate of climb, which is about 700 feet per minute. This brings up an important point. Although the takeoff roll for the Air Scout is very short, if there is an obstacle even 50 feet high at the end of the runway, you'd better plan on having extra room. The horizontal distance required to ascend 50 feet is a whopping 315 feet from the wheels-up point at 50 miles per hour forward speed, at the Air Scout's BEST rate of climb. Climbing and descending are accomplished less with the cyclic than with airspeed. The cyclic is adjusted to maintain altitude, but if the cyclic is not moved, increasing the throttle will cause the Air Scout to climb as well as accelerate. This is important, because an auto-gyro tends to maintain a nearly level attitude during all maneuvers, with only the rotor itself moving significantly. It's easy for a pilot familiar with other types of aircraft to over-control and induce oscillations that can lead to a crash. A very light touch is needed with the controls, and although the craft will maneuver at least as quickly as, say, a Piper Cub, it seems to do it more slowly because there is less sensation of motion to the pilot. A loss of forward motion can cause the rotor so stall. This type of accident occurs when the throttle is cut back too far, or the pilot tries to climb too quickly, or from several other mistakes. It is almost always recoverable, if there is sufficient altitude. Bringing the cyclic back to takeoff configuration, adding throttle, and allowing some altitude loss are usually enough. Adding power to the rotor may also be a possible temporary cure, but can cause torque effects to spin the fuselage as well. A beneficial quirk of the auto-gyro is that since it is constantly in auto-rotation, it can trade altitude for lift if necessary. Another problem is caused by pitching the nose too far down. This causes the airflow through the rotor to reverse, causing the craft to lose ALL lift. The rotor will break up before you can recover from it, and the craft WILL crash. Period. Landing is the only part of the flight that is not performed in a level attitude. To land, the nose is dropped (not too far) and power is reduced, gradually. Given the possibility of airflow reversal, it had BETTER be gradually. It is possible to do a complete power-off landing, but with a glide slope of about 4:1, only slightly better than a brick, so while safe enough, it certainly LOOKS scary, especially from inside the cockpit! When only a few feet off the runway, the craft is leveled off ("flared"), and the Air Scout settles in nicely. Or it bounces if you misjudged your altitude. Even though the craft may have a forward speed of 30 miles per hour when the flare is performed, after the flare, the ground speed is next to nothing. In a head wind, the landing roll may even be backwards! It's a very good idea to put the brakes on as soon as all three wheels are down. Armament The Air Scout auto-gyro is lightly armed at best. Armament consists of two rockets and two Stoner machine guns. The two rockets are fired together, and cannot be fired one at a time. These are the same rockets that were once used in the Huey helicopter rocket pods. They are notoriously inaccurate, having no guidance whatsoever. The pilot merely points the Air Scout in the right direction and flips the switch. The rockets will then fly more-or-less straight to the target. In actual fact, the rockets should be slightly more accurate when fired from the Air Scout than when fired from the Huey, because with the upward airflow through the rotor, the Air Scout will not "down-draft" the missiles and blow them off-course. The Stoner machine guns are housed in streamlined pods. They each have one 105-round disintegrating linked belt of 7.62 NATO ammunition, which is stored in a helical magazine. The helical magazine is merely a tube made with a rectangular cross-section large enough to hold the ammo, wound in an elongated spiral like a coil spring around the weapon. This is required because the box that the belt usually comes in will not fit inside the pod. New belts are fed in at the front of the gun pod, at the end of the magazine. An access panel near the gun's receiver allows the armorer to chamber the first round of the belt when it is first loaded. A chute on the side of the pod allows empty brass to be ejected to the side. One gun is mounted upside down to allow the ejected cartridges to be ejected outward from both guns, otherwise one of them would eject its brass toward the fuselage, but the helical magazine prevents the unusual mounting from causing feed problems. The machine guns are fitted with electric triggers, connected to the firing switch on the cyclic sticks in the cockpit. For ease of retrofitting a replacement gun, the electric trigger consists of a solenoid mechanism attached to a normal machine-gun trigger. Each pull of the trigger fires a ten-round burst (five rounds for the last burst when the belt runs out). Enterprising pilots may be able to make up slightly longer belts to get an extra few rounds (no more than 15 per pod) because of the length of the magazine, but doing so increases the chance that the guns will jam. These are not chain guns, and if there is a misfire, the gun will not fire at all until the pilot lands and clears the jam by hand. However, if one gun does jam, the other will still fire. Conclusion Hopefully, the information provided will give players and Project Directors enough information to realistically and effectively use the Air Scout. Although I have already expressed my preferences in a previous post for using a more modern alternate aircraft, specifically a small two- seat helicopter, that personal preference does not invalidate the Air Scout as a viable air asset for the Morrow Project. Hopefully it's even more viable now.