Flying C-152 Patterns Cessna's way
Last week (9-7-99)I failed a checkride at a certified Cessna Agency in a C-152. I was surprised to find out that with judicious use of initial trim setting for takeoff and power, it is Cessna's standard instructional procedure to negate any use of trim. The C-152 can be leveled from climb at 80 knots just by a reduction in power to 2200 rpm. No trim necessary. The abeam the numbers reduction of power to 1600 and the first ten degrees of flaps gives an approach speed of 70 knots and power at 1500. No trim necessary. The addition of flaps in the turns gives sufficient lift/drag to make this one power setting applicable for the whole descent. The base turn is accompanied by the second notch of flaps. Result is an approach speed of 65-knots. No trim necessary. The full flap condition is applied in the turn to final and the speed drops to 60 knots for the final approach. Keep 60-knots into the roundout and flare at 54 knot by keeping the nose slightly below the end of the runway. By letting students see where they are going we keep them from being frightened..
Insult was added to injury when I found that the C-172N could be flown and landed the same way. according to Cessna I have been flying their aircraft incorrectly for over 30-years. Even my first instructor, who became a factory representative for Cessna, taught me incorrectly by emphasizing the use of trim. This old-dog has learned a new trick. Oh, lordy, I have seen the error of my ways and have a ton of repenting to do. Where was Arenias when I needed him?
Transcript of most of the C-152 checkride is on Page 4. Instructors learn much more….
About the Cessna 152
C-152 Information
You should be warned about flying in a different kind of aircraft. There is just enough difference in a C-152 to create stress and interfere with your thought processes. The engineering of the C-152 is similar to the 150 except that where maximum flaps are only 30 degrees a 1/2 turn of trim seems sufficient for each 10 degrees of flap. After landing and flaps up, the aircraft is properly trimmed for climb. The C-150 is trimmed for level. Your use of the trim may produce a different result.
Cessna in a 152 Owners Advisory Letter has indicated that a C-152 which is run at full rich will result in a 40% increase in consumption along with a 70 minute reduction in flight time. The same figures would probably apply to other Cessnas.
Get a complete breakdown of how a C-150 and C-152 differ. Trim, flaps, electrical, and speeds. Go up and review all the airwork in a strange aircraft before doing any landings. --C-152 Use 10-degrees flap for both short and soft field takeoff..
Calibrating C-152 trim
C-152 to get 1500 you need to reduce to 1600 (similar to C-172's 1700). At altitude and imaginary numbers, power to 1600, hold altitude and heading until reaching 60 knots. Now quickly trim for hands-off but be sure to keep track of how much is required. Do the same for each 10 degrees of flap as you descend. Trim is added or put on by moving the wheel top down to bottom. Trim is taken off by moving The trim bottom to top. The best way to remember the trim setting is to predicate the movement of the trim from a constant power setting. You may need to do this a couple of times. You are trying to index the flap-trim ratios required to maintain 60 knots. Once you have developed a stabilized procedure for maintaining 60 knots you should be home free.
We will begin from level cruise and reduce power to 1500 while holding heading and altitude. The Airplane will decelerate and the rpm will fall to 1300. We will experiment with the number of trim turns and find that it takes to five turns to descend at 60 knots hands-off. When descent is about to commence at 60 knots we will put in 10 degrees of flaps,. Apply slight forward pressure with our thumb to maintain 609 knots and then take off one turn of trim. We will repeat this again twice more with additional 10 degrees of flaps so that we will have 30 degrees of flaps and will have removed three of the five initial turns of trim.
After doing this on a constant heading, we will make left and right 90 degree turns and then put in flaps to 20-degrees and trimming for 60-knot descent hands-off and making left and right 90 degree turns. Now we will put in the full 30-degrees of flaps and record the trim change required for the 60-knot final approach. The entire process will be repeated again from the beginning with right and left 90-degree turns. Once this is determined we will repeat the process from the beginning to confirm our settings.
For the go-around we will find that the addition of power and removal of flaps will have the aircraft trimmed for a relatively low speed climb. Take off one turn of trim for a 70 to 80 knot climb. At the application of power you must anticipate with right rudder to hold the nose in line with the runway. Forward pressure with the hand (Not just the thumb) is required to avoid an abrupt pitching up and to allow the aircraft to accelerate. At 70 knots relax the forward pressure and allow the number to seek its trimmed attitude and airspeed. Remove trim for the climb speed you desire. At the peak of our climb we want to 'calibrate' the trim required in transitioning from the climb to level cruise as it will exist with the power reduced. This will take several tries.
The last step in our calibration is to determine just where the trim is set when we add full power and remove the flaps. The aircraft should be trimmed somewhere between level flight and Vy climb. We will determine the amount of trim required and use that as one of the trim setting changes we make during the go-around in anticipation of climbing at Vy. Once the calibration is completed we have determined the landing procedure that will enable us to anticipate the power, flap and trim settings required for the standard stabilized approach.
CESSNA 152
From 6t climb
LEVEL OFF 2 TRIM UP
DESCENT
CH-1700 RPM
10 DEGREES FLAPS 1/2 UP TRIM
20 DEGREES FLAPS 1/2 UP TRIM
30 DEGREES FLAPS 1/2 UP TRIM
Short Field Takeoff:
Flaps set at 10 degrees. Release brakes and accelerate on the runway centerline. At 54 KIAS, the nose of the aircraft is raised smoothly and quickly to Vx pitch attitude - maintain 54 KIAS.
Establish normal climb 70-80 KIAS and retract the flaps. Since the Vy speed will vary with weight, it might be better to use the lower 70 KIAS when solo and 80 with two aboard. An old FAA manual once said that flap retraction should be made only after passing through 200'.
C-152
Short field
Brakes locked, full power, 10 degrees flap
Vx is 54 kts for best angle
Retract flaps at 60 kts and get Vy of 67 kts
The C152 take-off distance decreases by 10% for every ts of headwind component
Soft Field Takeoff:
Flaps set at 10 degrees. Elevator control to full nose up position. As the nose of the aircraft comes up to Vy pitch attitude, release elevator pressure as necessary to Maintain a maximum nose high attitude just short of dragging the tail. Level close to Vy airspeed before attempting to climb out of ground effect. Fly as close to the ground as you can. This will maximize your effective engine power and speed up acceleration. Ground effect ceases at 1/2 wing span altitude. With a 32' wingspan you have 16' of ground effect. The wing is already over 5' above the ground. Any altitude of the wheels over 11' will degrade aircraft performance. Stay low, accelerate and then climb.
If necessary, establish climb at 54 KIAS to clear any obstacles. If not, normal climb 70 - 80 KIAS based on weight. The FAA test does not include both a soft-short field requirement so the recommendation for airspeeds is good. In the FAA PTS guide you should accelerate to the 70 - 80 KIAS before climbing.
Retract flaps once clear of obstacles or when normal climb speed is established. 200' is former FAA recommendation before flap retraction.
Spins
In less that two turns you can recover just by letting go of the controls. beyond two turns to the left you must make a normal spin recovery. It is possible to tell which rudder will effect a spin recovery by deciding which rudder is harder to push.
Traffic Pattern.
Normal climb airspeed (67-70 KIAS) should be maintained as should full power.
Opposite the proposed touchdown point on the runway, apply carb. heat, then reduce power to approximately 1600 RPM Plane will decelerate to 60 knots and 1500 rpm. Trim for hands-off.
Apply 10 degrees flap and trim the aircraft for a 60 KIAS glide. in the 1990s you should not leave pattern altitude until turning base. Noise abatement procedure suggests not leaving pattern altitude until turning base. Try to keep the neighbors happy.
Turn base leg when runway numbers are at a 45-degree angle behind wing. This point may vary with wind conditions. The deceleration of Cessnas when the power is reduced to settle at 1500 RPM and altitude and heading are maintained the 45 degree or "key" position is nearly automatic. The "key" position has been dropped as a term by the FAA. The quickness used to go though the procedures should be faster as winds become stronger.
Bring the flaps to a 20-degree position, and retrim the aircraft to maintain 70 KIAS. The base leg is where you decide to widen out, square your pattern or angle toward the runway as a first choice. Second choice would be putting in additional flaps if high. After these decisions have been tried then change power. You should try to keep as many "constants" in your approaches as you can.
Lead the turn to final so as to roll out on the extended centerline. Accuracy in final alignment is directly related to how well the downwind was flown according to wind conditions. Even slight crosswinds on the ground must be considered as being stronger at altitude. Never exceed a 30-degree bank in the pattern. Standardized 30-degree banks will allow you to make all your turns more accurately. A 30-degree bank only increases the G force by .15. A shallower bank extends the "blind" time in the turn.
Apply full flaps (30 degrees) as needed and establish 60 KIAS glide. (trim as needed) The normal Cessna landing is made with full flaps. Full flaps improve landing accuracy. Crosswind or strong gusty winds are the only justification for using minimal flaps. C-152s can be slipped with flaps according to the POH.
About 1970 the FAA came out with a recommendation that power off landings not be considered "normal" Many instances of inability to re-apply power were occurring. The FAA now recommends that power be maintained into the actual flare and only be taken off at actual touchdown. Plan your approaches with the understanding that power will be applied. Then if power is lost, the removal of flaps will allow a safe power off landing.
I recently was shown that Cessna designed the C-152 so that it could be climbed at 70-75 knots at full power, leveled off at pattern altitude without the use of trim merely by reducing the power to 2200 rpm. This gave a downwind of 80 knots. (I thought it was inconsiderate of faster aircraft.) Abeam the numbers the descent could begin just by reducing power to 1500 and flaps added to make the aircraft fly at 70 knots at 1500 rpm. No trim necessary. The next ten degrees of flap could be added during the base turn and the speed become 65 knots. Full flaps added during the turn to final would give an approach speed of 60 knots. Further power changes were used to adjust the approach slope.
The landing and flare began at 60 knots and slowed to 54 knots. The nose was held relatively flat so that the student could see the runway. Nose up was limited so that the student could see the end of the runway. My ability to fly a heading was not done well at all. I flew well to the right. There was a LOC approach reciprocal to the selected heading which
I thought justified my misdirection. Apparently not.
Steep turns are performed at 80 knots with power added during the turn to maintain the 80 knot airspeed. I did not do well on the steep turns until I did them at cruise. Power off stalls are only performed with full flaps as though landing. The stall break must be fully developed before recovery.
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