Fighting Air Command Pilot's Notes for Stampe SV-4c N901AC
by Randy Wilson
These are my pilots notes for the Stampe SV-4c, which was the dual-control light biplane used by F.A.C. (Fighting Air Command) pilots who were getting ready to fly the WWI replica planes. Again, I have not had time to reformat this into HTML, so please excuse the old format for now.
Introduction The following notes and observations are intended to aid other Fighting Air Command pilots in checking out safely in this aircraft as well as providing information to those just interested in this plane. Operating procedures and flight characteristics for this aircraft have been determined from study of existing manuals and many hours of operation from both grass and pavement, in both the single and dual configuration. This is a revision and update of previous notes for this aircraft. General Information This aircraft is a two-place, production French military trainer built in 1948, although its design dates back to the early 1930's. It has an all wood structure and was used as an aerobatic trainer by many air forces well into the 1950's and even later. The engine is a four cylinder inverted air-cooled inline Renault 4P03 engine of 145 horsepower. The aircraft has very light controls and is really very easy and a pleasure to fly. It is fitted with mechanical wheel brakes, which operate in an unusual fashion, and a full-swivel, non-steerable tailwheel, and it can be operated with care from paved runways. Its lightness does, however, make it a handful in a gusty crosswind, especially on pavement. There being no electrical system, starting is by on-board compressed air or hand. Preflight Refer to the Cockpit Layout diagrams and Aircraft Data Table during the following discussion. The aircraft normally drips some oil near the left main wheel when not flown for a while, so don't be alarmed by this. After a normal preflight inspection of the exterior of the plane, including the flying and landing wires, turn the fuel on by pushing the fuel on/off rod forward in either the front or back cockpit. With the mags off, pull the prop through about 6 blades to check for any oil in the cylinders. Check the fuel quantity by looking at the sight gauge to the left under the upper wing center section, or climb up and visually check the fuel level in the tank in the upper wing center section. Open the left engine cowl to check the oil reservoir. A dipstick is attached to the screwed-in cap with markings in liters, a liter being a little more than a quart. I would have at least 5 liters for any extended flying, and at least 4 under any circumstances. The book says that the engine uses a quart an hour at cruise, so expect it to use oil. Use 60 weight non-detergent unless otherwise advised. If 60 weight is not available, 50 weight may be used, but do not use detergent oil. While the left cowling is open, check for any unusual oil leakage. The air valve for the starter should be open, i.e. turned fully counter clockwise. Open the right engine cowl and check for any fuel or oil leaks. If all is normal, and the engine is cold, pump up fuel pressure to 60 on the externally mounted gauge by actuating the push/pull knob on the fuel pump on the right rear of the engine. You can operate the pump and see the fuel pressure gauge from the right side of the engine. If the engine is warm and the pressure is at least 20, don't pump it up. Close the engine cowlings. Check that the belts and cushions in the front cockpit are secure and that the front mag switch is on BOTH. If you are going to use the air starter, check the air pressure gauge on the left in the front cockpit. Minimum pressure for a start is about 8. Also check that the small valve is closed (full clockwise) and the larger round valve is open (full counter-clockwise). Finally, the toggle switch marked Contact Passenger should be in the Branche position, as this enables the rear mag switch. Due to leaks in the air system, the starter usually will not hold a charge for more than a day. Startup If the engine is cold, after having pumped up the fuel pressure and ensuring that the mags are off, pump the throttle two or three times, then pull the engine through 5 or 6 blades, to prime it. Now on into the rear cockpit. The large lever to the right of the rear seat is for seat height adjustment. Take your weight off the seat, depress the button on top, and move the lever up or down. In the front cockpit the seat adjustment is the large round knob on the floor. Turning it adjusts the front seat height. To adjust the rear rudder pedals, pull up on the small black knob on the floor on the OPPOSITE side of the pedal you wish to adjust. Release the knob and let the pedal click into a detente. Note that there are stirrups on the rudder bars to keep your feet from falling off them while inverted. DON'T MASH THE STIRRUPS DOWN. Put your feet in them. I plan to remove these stirrups as soon as possible, as they are always getting mashed. The aerobatic harness includes a crotch strap and there is a second, separate safety belt that looks like it belongs on a stagecoach harness. Set the parking brake by pulling back on the brake lever and engaging the locking pawl. If there is enough air pressure in the reservoir, you can use the air starter. The air starter handle is on the far right side of the rear instrument panel. With the mags on and throttle cracked, pull the safety catch down and pull the air starter handle out a short ways. Let go of the safety, and use both hands to gently but firmly pull the air starter handle out until the prop spins and the engine fires. If the prop does not turn and the gauge shows adequate air pressure, reposition the prop to the normal hand starting position and try again. Also make sure that the air starter does not spin the engine backwards, which it can do occasionally. If the engine is hot when you try to start it, turn the fuel and mags off, open the throttle and pull the prop backwards through at least 12 blades. Be careful, as the engine has kicked back when hot even with the mags off. Turn the fuel and mags on, reset the throttle to open a bit and try a start. If the air system is depleted, the engine can be propped fairly easily, but the compression is fairly high and the prop very light, so use care. Being a French engine, you will note that it turns backwards from American ones. Again, if the engine is hot, you will have to back it up to get it unflooded. Once the engine starts, check for oil pressure, which is a little slow to come up. All of the gauges have minimum, maximum and normal ranges marked. See the Data Table for more details. Taxiing The Stampe has a hand brake lever which actuates both main wheel brakes together. This brake lever should be used very sparingly while moving, to prevent a nose-over. In normal operations, use it only as a parking brake or when running up. Since the plane has a rudder bar, there are no brake pedals for each side, but each wheel can be braked individually by pressing the rudder bar past full rudder on that side. The brakes are actuated by cables and can be a bit grabby, so be careful at first. Again, as practice for the WWI replicas, try to operate the Stampe as though it did not have brakes. The tailwheel is full swiveling and not connected to the rudder, so airflow is necessary past the rudder to steer, but the aircraft handles very easily. In a strong crosswind, however, taxiing can be very difficult. Visibility from the rear cockpit is better than in any of the WWI replicas. Runup The engine is fairly closely cowled, so try to point into the wind for runup or any prolonged idling. The oil temperature gauge is mounted outside and left of the front cockpit. If the weather is cold, be sure that the engine has had a chance to warm up. Set the parking brake or use chocks for runup. Use about 1500 rpm for runup or whatever the brakes will hold and check both mags. If the engine is very hot, you will note some mag roughness, so as soon as possible, try to let the engine cool some. Check the elevator trim on the left side of the rear cockpit. I normally fly with it most of the way forward, between 4 and 5. Takeoff If everything is normal, release the brake handle and slowly apply full throttle. Due to the direction the engine turns, you will need to add left rudder to correct for torque. The tail will come up almost immediately, and the controls are so light, be careful not to over lift the tail and put the prop into the ground. Also remember that the ailerons are both light and effective, even at low speeds, so don't over control there, either, as there is not much wingtip clearance to the ground. Climb out at 100 kph indicated with full throttle until you are at pattern altitude, then reduce power. I think that the airspeed indicators are running a little slow, so I will try to use the work "indicated" when I mean what I see on the instrument, as opposed to what the books say. Don't climb out too steeply on hot days, as this will worsen the engine cooling. About 1850 rpm seems like a good cruise setting once you have reached your altitude. Control Responses As I have already mentioned, the Stampe has very light, nicely balanced and effective controls. New pilots will have more problems with over control and will need to be careful at first on takeoff and landing. Don't, however, be afraid to use a lot of rudder, as it is necessary to keep you straight on takeoff. Air Work The book says the plane stalls at 65 kph (40 mph), and the indicated speed is less than that. The stall is definite with some buffet, and recovery is quick. In loops or slow rolls, the engine quits as soon as it is inverted, as there is no inverted oil system and the inverted fuel system has been disabled. Aerobatics are not generally authorized, but if this happens, retard the throttle, fly on through the maneuver, and the engine should pick up again in a few seconds. Don't pump the throttle, as this may flood the engine and delay a restart. Erect spins are comfortable and recovery normal. The emergency spin recovery technique works fine. A good coordination exercise is a series of wingovers, where the changing attitude and airspeed require constant smooth changes in the control inputs. If you get the nose too high, the engine may quit here, also. This will normally be demonstrated during checkout. Landing There is really only one problem in landing the Stampe, and that is getting it slowed down enough. On a normal approach, I would try to be no faster than 80 kph indicated on short final. If the wind is very light, you may even have to slip in at that speed, as the plane will float a long way if not slowed down. First landings should be full stalled three-point ones. In preparation for landing the WWI replicas, however, we will than practice power-off, tail-low wheel landings, as this is the technique used in the tailskid aircraft. The replicas do not float anything like the Stampe, but this practice gets you really used to seat of the pants, heads out of the cockpit landings. Remember, don't plan on using the hand brake lever to help slow down on landing, as this can cause a nose-over. If brakes are absolutely necessary, apply them very, very carefully and use as little as possible. Holding the throttle firmly closed during roll out will reduce the engine idle to a minimum and help slow the plane. You will also find that once the tailwheel is down on grass, the plane will slow fairly rapidly. Shutdown If the engine is hot, say above 75 degrees C, point it into the wind and let it cool down at around 800 rpm for a minute or two before shutting down. This will also make restarting easier. To shutdown the engine, turn off the mag switch and slowly open the throttle all the way. When the prop stops, close the throttle. Shut off the gas if the plane won't be flying again soon. There is an idle cutoff control, but it sticks and could cause your engine to die with the throttle closed, so we aren't using it, and it has been safetied off. The inverted fuel system lever has also been safetied off, as it will flood the engine if used in non-inverted flight. Also, what looks like a mixture lever next to the throttle, is for altitude compensation only, and can not be used to kill the engine. You might note that it can be moved forward only when the throttle is forward. Miscellaneous As originally configured, the instructor sat in the front cockpit and operated the engine starting controls. These have since been moved to the back cockpit in this aircraft, to make solo flight easier. This also explains the presence of the Contact Passenger switch in the front cockpit, which can disable the rear or student's mag switch if necessary. The mag switch handle is actually a key which can be removed when in the off position. These keys are normally left in the aircraft. Don't loose them! An engine fire extinguisher system was originally fitted but the extinguisher has since been removed. The controls for the system are located just below the air starter handle in the rear cockpit. The fuel tank is located in the upper wing center section. If a ladder is not available, it is possible to refuel by carefully standing on the longeron on the side of the front cockpit and having the fuel hose handed up over the front of the wing. We have copies of the original airframe and engine manuals for the Stampe, in French of course, if anyone wants to learn more about the aircraft. I also have some other documents which give the history of the type, again in French. Please check with me for access to any of the above. Aircraft Data Table The following Data Table has been compiled from the Stampe Technical Manual and other published sources. The original specifications are in metric units, matching the markings of the instruments. American units are also listed where possible. Fuel Pressure Minimum 200 gr/cm2 (2.85 psi) Normal 225 " (3.20 psi) Maximum 250 " (3.55 psi) Fuel grade - 80/87 octane or higher Fuel capacity - 90 liters (23.76 gallons) Fuel consumption at 2100 rpm - 32 lit/hr (8.4 gal/hr) Oil Pressure Minimum 2 kg/cm2 (28.4 psi) Normal 3 " (42.6 psi) Maximum 3.5 " (49.7 psi) Oil consumption at cruise - 1 lit/hr (1 qt/hr) Oil Temperature At Cruise 60 degrees C Full Throttle 75 " Maximum 90 " Engine Speed Normal Maximum 2400 rpm Red Line 2520 " Starter Air Pressure Minimum Summer 8 kg/cm2 (114 psi) Minimum Winter 20 " (284 psi) Weights for N901AC Empty Weight 1195 lb. (includes engine oil) Gross Weight 1700 lb.
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