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Lat/Lon: 29.30° N 98.47° W

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L13 Preflight and flight data

- STUDENT'S GLIDER PILOT FLIGHT TRAINING - Flight Instruction: $40.00 per Hour *
Motorglider/SelLaunch endorsement: (Grob 109 for Instruction or Demo rides)

Blanik L-13 Flight Characteristics

Ground Handling, Preflight and Flight- Blanik L13

 

Specifications

Limitations

Performance

Span

16.2m

Vne

136 Knots

Min sink

1.4 Kt@42kts

Length

 8.4m

max rough air

78 Knots

Best L/D

1 : 28

Height

2.09m

max winch

65 Knots

Stall clean

32 Knots

Wing area

19.15m²

max tow

76 Knots

 

 

Aspect ratio

13.7

Empty weight

292kg

Max AUW

500 kg

  • Assembly / disassembly is different. The front spars are vertical pins and checked in preflight by pulling on the wing fairing so that the securing safety pin is visible. The drag spar pin is different in that it is horizontal. See that the springs holding the wing fairing remain strong enough to minimize any slack in the fairing.
  • Control cable wear may be a bit more pronounced due to interior rubbing of the cables. It is important to check the cables for excessive wear by utilizing the starboard inspection port located approximately at mid-fuselage.
  • Check the control linkages in the tail. Keep in mind that the horizontal stabilizer is folded up for transportation and storage. Accessing the pins to facilitate this is through the tail cone. There are two schools of thought: #1) Insure that the horizontal pins are in place and then wire the tail cone in place thereby insuring that no one has pulled the pins, or #2) Leave the tail cone with just a removable clip so that every preflight inspection of the ship will be able to easily access the area to ascertain the status of the pins. What ever way is chosen, consistency is the key. If the ship is landed out have at least two people check this area upon re-assembly. This tail cone is weak structurally as it is only a cover. Due to the critical control linkages inside, if the cone is dented, check to see that no damage has been done to mechanisms within the empennage.
  • See that the rear seat pads are secured if flying the ship solo as the loose seat cushion is more prone to jamming the controls than the 2-33.
  • Be aware that it is possible for the front seat belts to be looped inadvertently around the rudder pedals of the rear seat due to their proximity and exposure to one another.
  • It is mandatory that the static / electric bond leads are in place between the structure and control surfaces as required by the type certificate.
  • Since the structural strength of the Blanik L-13 lies in its skin integrity, dents in the fuselage, and especially the riveted top and bottom fuselage ridges, will likely seriously weaken the ship therefore making it unairworthy until repaired.
  • Utilize the ground handling bar as the empennage of the L-13 is subject to weakening with excessive handling. The L-13 tail wheel is not only weak, but rolling the ship over the ground puts a lot of stress on the empennage. Also, it is easy to catch the elevator on ground objects unless the tail is lifted.
  • Be aware that in loading the L-13 with a "heavy" person in the front seat, the nose may dip. Upon recovering, the tail may "slam" back down to the ground. Again, the L-13 tail wheel assembly is even weaker than that of the SGS 2-33 and is not made to take such impacts.
  • In preflighting the canopy, see that no one has pulled the canopy jettisoning lever. It is possible that the lever has been pulled separating the securing wires but the lever can still give the appearance that the canopy is secure.
  • The canopy is more fragile than that on the SGS 2-33 as it is longer. In the open position, depending on which wing is down while preparing to load or while performing the pre-takeoff checklist, it is prone to slamming shut. Be advised that in shutting the canopy, it has a very sharp edge. Whether the pilot is shutting the canopy under control, or the wind is blowing it shut, do NOT throw your fingers underneath the canopy rail as you could have them cut or even chopped off!
  • Insure that the canopy is secure as the pilot is not able to check by sight alone. The canopy guide pins are sharp as well, and must be properly placed in the receiving wells for the canopy to be secured, fore and aft .
  • Do not handle the canopy by the "cut-out" ventilation windows. The plexiglass canopy will crack as well as the "megaplex" rails ... and they are expensive ! Again, do NOT allow anyone to handle the canopy by use of the vent windows...you'll crack the plexiglass!
  • You not only will check for proper main tire inflation, but you must also check for oleo shock inflation.
  • Note that the minimum weight of the solo pilot (in front) is approximately 150# (higher than the average SGS 2-33).
  • Weight-and-Balance (W&B) is referenced a different way ... in terms of mean aerodynamic chord (MAC).
  • With the L-13 tailwheel (rather than the SGS 2-33 front skid), the aircraft is subject to "windvaning". That is, upon completion of landing rollout or before takeoff, the ship can turn into the wind with no control input. The uncalled for turn during windvaning may lead to contact with other aircraft on the flight line or adjacent ground objects / people.

Blanik L-13 Flight Characteristics

The first thing to remember is that the Blanik is a tail-dragger as opposed to the SGS 2-33 which starts from rest upon its nose. Rather than pulling back on the stick or ensuring that the stick is full aft at the start of the take-off roll, the stick should be placed somewhere forward of neutral to unweight the tail and achieve a close-to-zero pitch angle as soon as possible. (Remember also that the tail wheel assembly, or small skid, is not especially strong thus the reason to "unweight" the tail as soon as aerodynamics allow it).
  • On takeoff, like the SGS 2-33, try to keep a relatively flat pitch until flying speed is reached. At this point, a slight aft movement of the stick will allow the L-13 to achieve flight without a lot of movement from the stick. This technique is much more important in the L-13 because it is more pitch sensitive. This will also minimize either "ballooning" high due to too much stick movement, or "struggling" due to insufficient flying speed when outside of ground effect.
  • With the fact that the L-13 is relatively pitch sensitive and coupled with the front control stick being so long, I recommend flying with your forearm resting on your right thigh even if it means grasping the stick a few inches from the top. In this way you will not be so tempted to over control and set up pilot induced oscillations (PIO) as your arm will be stabilized.
  • While the L-13 does have a front pad as a skid, it is not as durable nor meant to be used as extensively as that on the SGS 2-33. If you do inadvertently contact the ground with the nose skid, move the stick aft so that the tail is lowered and weight comes off the nose ASAP.
  • Upon landing, excessive use of the brake or some combination of brake and above normal loading in the forward seat may bring the nose to the ground upon the skid. Some aft movement of the stick should accompany brake application. In recovering from any nose down attitude, do not pull back on the stick so rapidly as to drive the tail down to the ground.
  • Like the SGS 2-33, shoot for a touchdown with only a slight nose high (or tail-down) attitude ... but not so much that the ship either 2-points or touches tail first. Contact with the ground should be always made with the main gear first.
  • Use of spoilers and wheel brake requires more thinking ahead of the aircraft as the two controls are separate but operated by the left hand. If landing with full spoilers the continued aerodynamic braking through the entire landing roll may lead to undershooting the desired point-of-rest if your hand drops to the wheel brake too soon. On the other hand, removal of spoilers too soon after landing and before much airspeed loss will lead to the aircraft "popping" back off the ground and leaving too slow an airspeed to provide for a soft secondary touchdown.
  • The L-13 brake is not as effective as the SGS 2-33 brake/nose skid combination. The L-13 brake should always be tested at the early determined point behind another aircraft, object, or person. Of course the L-13 skid is available for emergency braking, or the option of a ground-loop would be better than smacking something else! [It is not sound operating procedure to "float" down the runway expecting the wheel brake to stop the aircraft!]
  • The prelanding checklist now has new items ... gear and flaps! While the L-13 can be landed with the gear in the "up" position, the gear oleo shock is not effective when the gear is in this position. Resulting high axle loads if landed in this configuration on a hard and/or rough field could cause damage. This retractable gear is good for practice (for transition to high performance ships) as the L/D is not effectively improved when the gear is in the "up" position. Unless the flaps are greased and worked frequently, it will take a "circus strongman" to operate them! Nonetheless, their position should always be checked as there is some lowering of stall speed (about 2 knots) with full flap use; and an airspeed limitation with their extension.
  • The presence of flaps does mean that one additional airspeed restriction must be obeyed ... the top end of the white arc on the airspeed indicator is the maximum flap extended speed of 60 knots.
  • Blanik spoilers are more effective than the SGS 2-33A in providing a steep glide path; should it be desired. However, slipping the L-13 is not quite as effective as it is in the SGS 2-33 although it can be done. In slipping the Blanik proper airspeed control is essential due to the Blanik's stall characteristics. Therefore it is preferred to control glide path in the L-13 with only spoiler use. It is also not recommended to slip the L-13 with spoilers or flaps extended.
  • Unlike the SGS 2-33, the L-13 has a noticeable increase in stall speed (3-6Kts) with spoiler application as well as a requirement to adjust pitch to simply maintain airspeed caused by spoiler drag. With spoiler application be prepared to simultaneously lower the nose for the maintenance of your desired approach airspeed.
  • At high speed the L-13 can be noisier than even the SGS 2-33. There can be quite a few rattles in the 90-100 knot speed range, especially if the tail bushings are a bit worn.
  • The Design Maneuvering Speed is 78 knots with a Never Exceed Speed of 136 knots. The Maximum Aero-Tow Speed is 76 knots ... Winch Launch at 65 knots. Stall speed without flaps extended is 32 knots ... and with flaps extended at 30 knots. Calm air approach speeds without flaps in the L-13 should still range from 50-55 knots; and a sound 55 knots if full spoilers are to be deployed.
  • On aerotow the Blanik develops slack line easier because it is aerodynamically cleaner. Pay closer attention to the tow plane. In addition, the tow plane sight picture is different in the Blanik due to the lower canopy, flatter tow angle, and the lack of a vertically mounted pitot mast than that of the SGS 2-33.
  • Become familiar with the instrument and control locations as they are quite different than that of the SGS 2-33.
  • At tow release you must verify that the tow line has released before beginning any movement away from the tow plane. Blanik releases do have a tendency to report a detente in the release mechanism upon pulling the release handle; thereby giving a sense of false tow line release. Relatedly, be sure that the tow ring is properly seated before takeoff.
  • Although the Blanik is approved for certain aerobatic maneuvers, do not attempt aerobatic flight without instruction! Aerobatics are not approved in club ships except for spins during instructional sessions. Again, self taught aerobatics are dangerous!
  • The Blanik presents a "different" sight picture to the PIC in turns due to the forward sweep of the wings. Transition pilots may initially have excess pitch down in turns and gain airspeed during ground reference maneuvering.
  • The roll rate in the L-13 is better than that of the SGS 2-33; although the Blanik roll rate is not as relatively sensate as its pitch control.
  • Rudder effectiveness is very good due to the size of the vertical stabilizer and rudder combination. The rudder is effective enough to demand proper use or else slips and skids will easily result.
  • Due to the definite stall break characteristics of the Blanik, coordinated flight and proper airspeed must be maintained in the pattern, especially in the base and final legs of the approach. The Blanik is less tolerant of "sloppy" coordination due to its capability to stall break.
  • The L-13 is an "honest" aircraft when it comes to stalls. All of the signs of impending stall are present (getting quieter from airspeed loss, controls getting sloppy, control buffet). At the stall the Blanik exhibits a well defined stall break from any attitude, unlike that of the S.S. 2-33. However, the L-13 gives less time from warning signals to stall, in addition to the break. [This is due to less wing dihedral wash-out]. I stress that the L-13 will stall with less apparent pitch than the S.S. 2-33.
  • Stalls lead to spins in the Blanik if prompt and proper stall recovery is not undertaken!

The Blanik can enter a spin from any one of three conditions of flight:

  From a straight ahead stall, rudder application at the time of stall will develop a spin in the direction of the rudder application;

  A turning stall will tend to lead to a spin in the direction that the aircraft "falls out"; and,

  A cross-control stall entry is a good example of why pitch is to be used first (before aileron or even rudder) in a turning stall recovery. The Blanik will spin in the direction opposite to applied aileron at the point of stall.

Spins can be simple (spinning only) or bi-modal (spinning and pitching). Be prepared for steep descent angles (as much as 70 degrees down). The rate of spin is approximately 3.5 seconds/revolution with a loss of altitude of 320 feet/revolution.

  • The crosswind capability of the Blanik is listed as 10 knots, that is a little lower than the S.S. 2-33.
  • In securing the Blanik, do not use the tip points as the major support, but rather the mid-wing tie down rings.

In summary, the Blanik is an excellent sailplane for intermediate and advanced training. Due to its characteristics, this ship is actually a better ship for transition to high performance fiberglass aircraft than some two-place glass ships. Due to its stall characteristics, it provides a better platform for stall and spin awareness and demands a higher degree of coordination for the aforementioned reason.

 

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*Flight Instruction $38/hour *
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