Distance Wires - Height Wires 75 Ft.
50 Ft.
25 Ft.
2000 1900 1800 Runway Timing Light Figure 5 - FIXED GRID From information obtained by any of the above methods in the previous section, the observed data may be plotted as in figure 6. This figure is usually included in the final report as is the corrected takeoff data.
35 T
OBSERVED TAKE OFF DATA 30 _Type Aircraft & No.
Gross Weight (Seconda) 25 20 Power Settings Configuration IAS at 50' TAS at 50° 100 HEIGHT ABOVE RUNWAY (It) Las at TAS at 1 5 TIME Wind Component 10 Along Runway Temperature Baron. Press.
5 Type Runvay 500 1000 1500 DISTANCE ALONG BUNWAI, (It) Figure 6 - CORRECTED TAKEOFF DATA
4. All takeoff performance data are corrected to sea level standard conditions and zero wind unless otherwise specified. A minimum of six takeoffs should be made and measured. Each test may be made using the appropriate speed over the obstacle.
(c) For simple airplanes equipped with reciprocating sea level engines, an acceptable data correction process to produce the takeoff distance for standard sea level no wind conditions is presented in figure 7.
TAKEOFF DISTANCE - SEGMENT METHOD (ACCELERATION SEGMENT) Target Speed at 50 ft. Vsa KCAS 75 Indicated Pressure Altitude, ft. 3750 (recorded] Calibrated Pressure altitude, ft. 3750 [this example assumes that there is no difference between ind. And cal.] Obs. OAT, deg F [recorded] Std lamp @ Alt,, teg F (line 2) 46 [59 - 00356616 * line 2] Density Altitude @ line 2 and line 3, It. 5187 I((1-6.87535 * 10* * line2$361 × (518.688 / (line 3 + 459.7)) 0335 - 11/(6.87535 * 105) Density @ line 5 0.00212126 10.0023769 * 1-(6.87535 * 10** line 2) *2565 Density Ratio 0.89241259 [line 6/0.002377] Sq root of density ratio in line 7 0.9447 (line 7) "3g 9 Obs. Comp. WindVelocity (+ head - tail), knots 3.00 [record] 10 Accelerate Airspeed for Test Cond. (TA5) 79.39 [V50/line 7] 50° speed corrected for alt Accelerate Ground Spd. for Test Cond. (TAS) 76.39 [line 10-Line 9] 50' speed corrected for alt. And wind Equivalent Altitude @ line 2 and line 3, ft 4267 (line 2-(0.36* (line 2-line 8)| 13 R/C @ Vse @ line 12, ft/min 450 [look up on equivalent alt, climb performance chart] 14 R/C@ Ya @S.. It/min 495 [look up on equivalent alt. climb performance chart] 15 Accelerate Run Power Corr. 0.91 [line 13/ine 14] 16 VSE AIR/V50 GND 1,04 [line 10/ine 11] 17 Accelerate Run Wind Corr. 1.07 [line 16) 83 18 Accelerate Run Density Corr. = line 7 0.89 [just the density ratio from line 7] 19 Observed Accelerate Dist. to Speed @ line 11, ft. 820 frecord) 20 Corr. S.L.. Accelerate Dist. to Vso, ft 714 [line 19 * line 18 * line 17 * line 15] 31 Average S.L. Accelerate Distance, ft 755 [average from total runs] climb segment 22 Via Speed @ 50 ft. std. S..., knots 97 [look up on climb chart!
23 R/C @ Vso and std. S.., ft/min 495 | [line 14] 24 Horizontal Distance from Lift-off to 50 ft 789 [¡50 it (line 22 * 1.69 * 60)/line 23)| S.L. Total Distance from Start to 50 ft, ft 1544 [line 21 + line 24] ground distance to 50' speed + horizontal component (distance) to climb 50' taken from climb chart Notes:
This chart is for sea level, std. Day takeoff distance to 50° Aircraft configuration, flaps and weight, should be specified
3. Landing gear is assumed down until after 50' point - if its determined that retracting the gear would significantly increase drag and therefore takeoff distance - a caution should be included in the handbook.
Figure 7 - DETERMINATION OF STANDARD S.L. TAKEOFF DISTANCE SEGMENT
METHOD (ACCELERATION SEGMENT) 9
1. The Takeoff Distance Segment Method (figure 7) is a simplified method to collect takeoff distance data to a 50-foot obstacle clearance height. This method is appropriate for simple airplanes because it is conservative and it does not require any elevation instrumentation to determine the 50-foot point. This method sums the ground acceleration, without any climb, to the point where the target obstacle cl earance speed is achieved, with the horizontal distance to climb 50 feet.
2. A simple way to understand the takeoff distance segment method is to understand it in terms of work/energy. The total distance is the sum of the work/energy required to accelerate to the obstacle clearance speed without any climb and the work/energy required for a steady climb of 50 feet (out of ground effect). The data for the climb segment should be based on the data reduction used for climb testing. Airplanes with fixed pitch props should use the equivalent altitude method, whereas airplanes with constant speed propellers should use the density altitude method. Radio calls can allow ground observers to mark distances to planned liftoff and obstacle clearance speeds. This figure presumes the test to have been conducted within the +5/-1 percent weight tolerance of § 23.21, and that correction of off-standard weight is not necessary. For the same type of airplane, an acceptable method of determining the approximate effects of altitude and temperature upon takeoff distance is presented in figure 8.
-6.87535 * 10* Determination of Takeoff Distance to 50 ft at Given Altitude and Temperature [recorded [ this example assumes that there is no difference between ind. and cal. ] recorded 00356616 * line 21 59 - I (1 - 6.87535 * 10* • line 2) 52881 * (518.688 / ( line 3 + 459.7 )) 6235 - 11/ I 0.0023769 * ( 1- ((6.87535 * 10* ) * line 2) I line 6 / 0.002377 1 I (line 7) 0.5 g line 2 - (0.36 * ( line 2 - line 5)) 1 indicated corrected for instrument error ] [ look up on equivalent alt. climb performance chart ] [ line 13 / line 14] [ from the chart shown in fig. 71 [ line 14 / ( line 13 * line 7)] • (50 * 60 * line 10) / ( line 13 * line 7 * line 12)) [ line 15 + line 16] 3750 3750 68 46 5187 0.002121 0.892413 0.9447 4267 76 450 495 0.91 755 931 568 1498 calibrate Pressure Artude f Temperature, deg F St'd temp @ Altp, deg F (line 2) Density Altitude @ line 2 and line 3, ft Density @ line 5 Density Ratio Sq. root of density ratio in line 7 Equivalent Altitude @ line 2 and line 3, ft Vso- Calibrated Airspeed, knots R/C @ Vso @ line 9, ft/min R/C @ Vso @ S.L., ft/min Accelerate Run Power Corr. Distance to accelerate to Vso @ S.L.Std Distance to Accelerate to Vso at line 1 and line Distance to Climb to 50 ft Total Distance from Start to 50 ft.
10 11 12 Figure 8 - DETERMINATION OF TAKEOFF DISTANCE TO 50 FEET AT GIVEN ALTITUDE
AND TEMPERATURE 11
3. The correction process of figures 7 and 8 presume the acceleration distance to vary inversely as the excess thrust that exists at the 50-foot speed, rather than inversely with the “effective acceleration” which generally corresponds with a speed approximately 30 percent lower.
This simplifying assumption enables use of the airplane's climb performance ratio as an approximate correction factor for the effect of altitude and temperature upon acceleration distance, and thereby avoids the need for thrust computations. However, the process is not considered to be valid for extrapolating performance to gross weights or wind conditions, which differ significantly from those of the test.
4. This method calculates total takeoff di stance and not a ground run distance.
Part 23 does not require any ground distance data for small airplanes; however, it would be helpful to the pilot to include the ground distance numbers that are determined using this method. The ground distance for sea level, standard day conditions at gross weight could be provided with correction factors for increasing altitude and temperature.
(d) Glossary of Terms :
H p - Pressure Altitude OAT - Outside Air Temperature H D - Density Altitude σ - (sigma) Density Ratio H e - Equivalent Altitude α - Runway Slope, in Degrees R/C GU - Rate of Climb, Gear Up b - Wingspan E - Oswald Efficiency Factor g - Gravitational Constant (.6 may be assumed in the absence of analysis or test)
c. Climb .
(1) Regulations Reference . Sections 23.65 and 23.1587.
(2) Discussion . Section 23.65 requires the determination of climb performance, which exceeds a minimum standard. When AC 23-8B was published, it no longer included the previously longstanding equivalent altitude method of reducing climb data for fixed pitch propeller airplanes.
The elimination of the equivalent altitude method of reducing climb data leaves no practical method for simple airplanes with fixed pitch propellers to reduce climb data.
• The density altitude m ethod of climb data reduction for constant speed propeller airplanes is still embodied in AC 23-8B.
• For sm all airplanes, simplified me thods are acceptable as follows:
(a) Equivalent Altitude .
1. Data reduction procedures using the equivalent altitude method are an acceptable means of compliance for small airplanes with fixed pitch propellers. This method is described in National Advisory Committee for Aeronautics (NACA) Report 297. The data reduction form shown in figure 9 may be employed. This method is applicable to both saw tooth and continuous climb data sets. Full throttle operation is required for valid results.
Climbs - Equivalent Altitude Method Wing Span, b 33.30 Oswold Efficiency Factor, e 0.80 Indicated Pressure Altitude 3750 [recorded] 2 Calibrated Pressure Altitude 3750 [this example assumes that there is no difference between ind. And cal.] OAT. CAT, deg F 68 [recorded OAT. CAT, deg C 20 [from A/S calibration charts] Indicated Airspeed 68 recorded Calibrated Airspeed 70 [from A/S calibration charts] Observed R/C, ft/min 442 [altitude delta / time (minutes)] Std temp @ Alti, deg F (line 2) 46 [59 - .00356616 * line 2] ABS OAT, deg RI 528 [459.7 + line 3] 10 ABS Std. Temp., deg R 505.24 [518.688 - (.00358616* line 2] 11 Temperature correction 1.04 [line 9 / line 10] 12 Density Altitude @ line 2 and line 3 5.187 (1-6.87535 * 10* * line 2) 32561 * (518.688 / (line 3 + 459.7)1:231 - 1]/(-6.57535 * 10* 13 14 Density @ line 12 (1 / Sq. root density ratio) at line 12 0.002121 1.1096 11/(518.888 (1= (8.87535 * 10) * line 2) 82581) / (line 3 + 459.688) °3 0.0023769 * (1-(6.87536 * 104) * line 2) 4.28411 15 Test airplane wt. 1745 [recorded] 16 Weight Correction 0.99 WSTD/line 15] 17 18 Dynamic Pressure True Airspeed 13.81 78 [line 8 + Line 14] 10.5 + line 13 ‡ (line 17 + 1.467)?l 19 Calculation Factor 38471 ¡line 18 ‡ pie + e ‡ b'] 20 Ind. Drag @ Test Wgt 79 [line 15'/ line 19) 21 Del Di due to Wgt -1.35 line 20 ‡ (line 16' - 1.0)] 22 R/C corr. For Wgt and Temp. 488 [line 7 ÷ line 11)/line 16] 23 Del R/C due to del Di -5.36 [(line 21 = line 17 + 88)/W.l 24 Equivalent Altitude 4267 [line 2 - (0.36 ÷ (line 2 - line 12)] 25 R/C [Std. Atm. @ Alt. line 24] ft/min 471 [line 22 - line 23] Standard Day R/C Expanded to Approximate Effects of Altitude and Temperature Example is for 5000 ft at ISA plus 20 degrees C Pressure Altitude 5000 OAI SI deg C 5.15 [(line 1 + (-0.002) + 15.15] OAT S, deg F 41.27 [(line 9 + line 2) / 5) + 32] 4 OAT, deg C 25.15 [This is line 2 plus or minus the temperature value selected. For this example it is +20] OAT, deg F 77 [(9 + line 4) / 5) + 32] ABS OAT SI deg R 501 [line 3 + 459.7] 7 ABS OAT, deg R 537 [line 5 + 459.7] Temp. correction: Pressure Ratio 0.871714 0.93 11- (6.87535 + 10) + line 2) 2587 [line 6 / line 7] 10 Density @ Alt, and OAT in lines 1 and 0.001933 [line 9 ÷ 0.002377 ‡ line 10] 11 Alt. density @ Alt, and OAT in lines 1 and 7280 [Look up from std. Atmosphere tables.] 12 Equivalent Altitude 5821 [Go to the std. Day climb performance plot and use the performance at 5821 ft for the Performance at 5000 ft and 20 deg C above ISA (warmer day)] Expand for the Approximate Effects of Weight: (This is optional for airplanes under 6000 pounds unless they have a turbine engine) 13 Density Ratio 0.813272 [line 11 / 0.002377] 14 1 / (sq root density ratio) 1.108874 [1 / (line 14) °3] 15 Airplane Weight, Selected 1500 [self-explanatory] 16 Weight Correction 1.15 [Gross Weight / Line 16 selected weight] 17 _ V, mph 61.00 [recommended climb speed] 18 19 20 Draginduced @ Selected Weight Dynamic Pressure TAS 104.36 67.64 7.74 [line 18 ÷ line 15] Tine 16' / (3.14 *b? * e * line 20)] 10.5 + line 11 + (line 18 " 1.467"] 21 22 Del Drag Due to Weight Delta Rate of Climb, ft/min 34.45 96.44 I(2 / (3.14 ‡ b' + e + line 11 + (line 19 + 1.487) + (1.737) = (line 18) / 1730) ‡ 80] [line 21 ÷ (line 17) - 1)] Figure 9 - DATA REDUCTION FORM CLIMBS - EQUIVALENT ALTITUDE METHOD 13
2. The essential limitation to this method is that the correction to the observed climb for power, when the outside air temperature is not standard, is predicated upon the assumption that all engine controls are fixed. That is, no correction for variation in throttle setting, mixture, carburetor heat, etc., is made, and a climb at any part throttle setting is corrected for that throttle setting but not to full throttle. This method is referred to as the “equivalent altitude method” since it employs a correction to climb performance test data for atmospheric temperature variations from “standard” which indicates that the performance obtained under any atmospheric temperature and pressure may be obtained at some “equivalent altitude” in the standard atmosphere. The “equivalent altitude” may for the purposes of this AC be expressed as the “pressure” altitude plus 0.36 times the algebraic difference between the “density” altitude and the observed “pressure” altitude (“equivalent” altitude will always lie between the “pressure” altitude and the “density” altitude). As mentioned above, when climb performance is referred to “equivalent” altitude, no further correction for the effect of power changes needs to be made, and the final climb obtained thereby is that which would be obtained in the “standard atmosphere” at a height equal to the “equivalent” altitude when the power plant is operated as it was in the actual test.
(b) Density Altitude . Data reduction procedures using the density altitude method are an acceptable method of compliance for small airplanes with constant speed propellers. This method is outlined in AC 23-8B. The data reduction form shown in figure 10 may be employed.
This method also is applicable to both saw tooth and continuous climb data sets.
FORM ACE-1762 DEPARTMENT OF COMMERCE FORMERLY FAF-17 CLIMB CORRECTION - SHEET 1 CIVIL AERONAUTICS ADMINISTRATION (1-2-47)
AIRPLANE ENGINE PROPELLER PAGE
MODEL MODEL MODEL STD. WT. RATING RPM BLADE PROV. WT. METO RPM WING AREA GEAR RATIO NO. BLADES REPORT NO.
SPAN "E" MIN. OCTANE TYPE "F" ENG. COWL FLAP OPENING CRIT. ALT. DIA FLIGHT NO.
(RATED) CONFIGURATION CRIT. ALT.
(TEST) NO. ITEM CLIMB CLIMB CLIMB CLIMB CLIMB NO. NO. NO. NO. NO.
INDICATED AIRSPEED (MPH)
TRUE INDICATED AIRSPEED (MPH) VP/PO TRUE SPEED = (2) /13) (MPH)
TIME (MIN) OBSERVED CLIMB (FT.)
7 OBSERVED RATE OF CLIMB R/C (FT./MIN.)
AVERAGE PRESSURE ALTITUDE Ho (FT.)
OBSERVED OUTSIDE AIR TEMP. (°F) 10 ABSOLUTE OBS. OUTSIDE AIR TEMP. (°F) 11 STANDARD AIR TEMP. AT ALT. (8) (°F) 12 ABS. STAND. AIR TEMP. AT ALT. (8) (°F) 13 DENSITY ALTITUDE HD (FT.)
14 STAND. AIR TEMP. AT ALT. HD (13) (°F) 15 ABS. STAND. AIR TEMP. AT HO (13) (°F) 16 OBSERVED CARB. AIR TEMP. (°F) 17 ABSOLUTE CARB. AIR TEMP. (°F) 18 CARB. HEAT RISE = (16) - (9) (°F) 19 OBSERVED ENGINE RPM (RPM) 20 OBSERVED MANIFOLD PRESSURE (in. Hg) 21 ACTUAL WEIGHT (LBS.)
Figure 10 - DATA REDUCTION FORM CLIMBS - DENSITY ALTITUDE METHOD (SHEET 1 OF 2) 15
FORM ACE-1762 FORMERLY FAF-17 (1-2-47) CLIMB CORRECTION - SHEET 2 NO. ITEM CLIMB NO. CLIMB NO. CLIMB NO. CLIMB NO. CLIMB NO.
22 ABS. OUTSIDE AIR TEMPERATURE _ (10) ABS. STAND. AIR TEMP. (Hp) 23 ABS. STD. AIR TEMP. (H) = 17) ABS. CARB. AIR TEMP 24 ABS. STD. AIR TEMP. AT Ho V ABS. STD. AIR TEMP. AT HD + CAHR - V (15) + (18) 25 WT. TO BE CORRECTED TO (WE) ACTUAL WEIGHT 26 (WT. TO BE CORRECTED TO? -1-5-1 (ACTUAL WEIGHT)?
27 ENGINE POWER FROM POWER CURVE (HP) 28 ACTUAL BRAKE HORSEPOWER = (27) X (23) (HP) 29 STD. BHP ATTAINABLE AT HO (HP) 30 BHP OBTAINABLE AT HD = (29) X (24) (HP)
ACTUAL RATE OF CLIMB OF TEST AT TEST 31 WT. & STANDARD COND. = (7) X (22) (FT./MIN.)
32 n - PROPULSIVE EFFICIENCY 33 BHPA CHANGE - ACTUAL TO THAT AT HD = [(30) - (28)] 34 THP A CHANGE-ACTUAL TO THAT AT HD = (32) X 1HP) 35 INDUCED POWER REQ. _ AT TEST WT. (HPRI) 3.013eb? × (3) × (2) (21)? (HP)
INCREMENT OF INDUCED POWER 36 REQUIRED CHANGE-FROM TEST WT. TO FINAL WT. AT CONSTANT SPEED = - (35) X (26) (HP)
THP CHANGE DUE TO HP CHANGES OF 37 (34) + (36) AT FINAL WT. = (34) + (36) (HP)
R/C CHANGE DUE TO HP CHANGES 38 OF (37) A T FINAL WT. = (37) x 33,000 (FT./MIN.)
39 TEST R/C COR. TO WF = (31) X (25) (FT./MIN.)
40 FINAL R/C AT WF + HD(STAND) = (38) + (39) (FT./MIN.)
Figure 10 - DATA REDUCTION FORM CLIMBS - DENSITY ALTITUDE METHOD (SHEET 2 OF 2) 16
(c) Engine Power Correction . These methods make no direct engine power corrections for the difference between calibrated and rated power. The determination of the "equivalent" altitude empirically adjusts the data to allow for atmospheric effects on power for fixed pitch propeller installations. If further corrections for engine power (differences between calibrated and rated power) are desired, the following process may be utilized for either the equivalent or density altitude method:
1 . The airplane climbs because a surplu s of power is available in accordance with the relationship, R C BHP Wpe x=× ×η 33000 where, R C = rate of climb, feet/minimum ηp = propulsive efficiency (.75 ma y be used for constant speed propellers and .65 for fixed pitch propellers if no better value is known) BHPex = excess brake horsepower available W = aircraft weight, pounds
2 . To develop a power correction, the above equation is solved for,
() ( )BHP R C Wex p=× ÷ × η 33000
where, R C = sea level rate of climb developed in flight test W = airplane approved gross weight
Also, BHP BHP BHPex avail req= −
where, BHPavail = maximum power available at sea level at the manifold pressure and engine rpm, which can be achieved.
BHPreq = power required for level f light at the climb speed.
The power correction must be applied to the BHPavail term. For example, the calibrated engine produces 101 percent rated power, then the BHPavail must be reduced by 1 percent.
Therefore, ()BHP BHP CORR BHPex avail reqcorr =− −
where, BHPexcorr = excess power remaining following the power correction power correction to available power CORR =
18 Using the corrected excess power, resolve the original equation to obtain the corrected rate of climb,
R C BHP Wcorr pe x corr=× × ÷η 33000
(d) Data Requirements . In order to provide AFM data showing the effect of altitude and temperature as required by § 23.1587, a sufficient number of climbs through a range of speeds must be completed allowing rate of climb to be plotted against equivalent or density altitude (whichever is appropriate). This relationship is then used to produce the AFM performance information. It is also necessary to perform climbs at different speeds in order to determine the best rate of climb speed Vy.
d. Landing .
(1) Regulations Reference : Sections 23.75 and 23.1587.
(2) Discussion .
(a) Measurement Methods . Section 23.75 requires the measurement of the distance required to land over a 50-foot obstacle and come to a stop. The methods described for takeoff measurement are equally applicable for landing performance measurements.
(b) Data Reduction . A number of ways exist to correct the test data obtained above to standard conditions at sea level. One method that has been used is shown in figure 11. These forms are oriented for reduction of test data obtained by photographic methods but may be adapted to other data collection methods.
TITLE PAGE PREPARED BY DATE REPORT NO.
CHECKED BY DATE MODEL
CORRECTION OF LANDING DATA TO STANDARD CONDITIONS LANDING NUMBER 1 4 1 W† = TEST WEIGHT (LBS.)
2 W$ = WEIGHT TO BE CORRECTED TO (LBS.)
W¡/Ws = (1) / (2) 4 Hp = PRESSURE ALTITUDE @ GROUND DURING TEST (FT.)
OAT = TEMPERATURE AT GROUND DURING TEST (°F) HD = DENSITY ALTITUDE (FT.)
7 p = DENSITY @ (4) + (5) (SLUGS/FT.)
8 PF = DENSITY TO BE CORRECTED TO (SLUGS/FT.)
9 (7)/ 8) 10 TA = AIR TIME FROM 50 FT. TO GROUND (CAMERA DATA) (SEC) 11 Vwo = OBSERVED WIND VELOCITY (FT/SEC.)
*12 VWH = 1.376 (11) = WIND VELOCITY AT 50 FT. (FT./SEC.)
13 VHO = OBSERVED VELOCITY @ 50 FT. (CAMERA DATA) (FT./SEC.)
14 VH = (12) + (13) = TRUE AIRSPEED AT 50 FT. (FT./SEC.)
15 Vco = OBSERVED CONTACT VELOCITY (CAMERA DATA) (FT./SEC.)
16 VCA = (11) = (115) = TRUE AIRSPEED AT CONTACT (FT./SEC.)
17 VCA/VCO = (16) / (15) 18 (VCA/Vco) 1.85 = (17) 1:85 = WIND CORRECTION FOR GROUND RUN 19 VVH = OBSERVED VERTICAL VELOCITY @ 50 FT. (CAMERA DATA) (FT./SEC.)
20 1.210 (14) + (16) 21 .00575 (14) x (20)
(19) 22 1.185 (10) 1/7 * Assuming VWH = Vwo Figure 11 - DATA REDUCTION FORM - CORRECTION OF LANDING DATA TO STANDARD CONDITIONS (SHEET 1 OF 2) 19