Laboratory 1
Climb Performance
Gregory R. Whitney
David Hughling
TA: Eduardo Gildin
September 24, 2001
University of Texas at Austin
ASE 167M
Abstract
The climb performance of a Beechcraft Bonanza A-36 was investigated with the use of the CAT II simulator at the University of Texas at Austin. The climb performance was determined by recording the airspeed and rate-of-climb at several altitudes between ground level and 6000 ft. The effects of the flaps on the lift and drag characteristics were also studied. It was found that the Bonanza had the fastest rate of climb at approximately 84 knots which produced a maximum rate of climb of 650 ft/min. The maximum flight path angle was calculated to be 6.5 degrees.
Table of Contents
Objectives………………………………………………………………………….
Procedure…………………………………………………………………………..
Discussion…………………………………………………………………………
Experiment Data/Test Results……………………………………………………..
Conclusions…………………………………………………………………………
Recommendations………………………………………………………………….
Reference…………………………………………………………………………...
Appendix A………………………………………………………………………...
Objectives
The objectives of the experiment were to:
1. Learn the relationships between pitch, flight path angle, power, flaps, airspeed and trim.
2. Determine the flight parameters for the best rate-of-climb and the best angle-of-climb.
Procedure
Once the pre-flight checklist was complete, maximum power was applied and the plane entered a climb to 2000 ft at a climb-rate of 800 ft/min and a speed of 100 knots. At 2000 ft, speed was increased to 120 knots and a vertical airspeed of 850 ft/min was maintained until 3000 ft was attained. At 3000 ft, the engine was reduced to 2300 RPM and airspeed was adjusted to 80 knots. Airspeed was maintained at 80 knots until the altimeter read 6000 ft. At 6000 ft, the plane was slowed to 70 knots and a climb-rate of 350 ft/min was achieved. Once 6000 ft was reached, power was adjusted so that the airspeed was stable at 175 knots. The power settings were then adjusted for less power until the airplane was flying at a suitable flaps extension speed. Flaps were lowered and the reaction of the airplane was noted. After the airplane had settled into straight and level flight, the airplane was put into an increasingly sharper descent up until the final flaring maneuver just prior to touchdown. During various altitudes, the current airspeed and rate-of-climb was recorded for later analysis. For a detailed list of the procedures, see page 25 of the lab manual.
Discussion
The two objectives of this experiment were to determine the relationships between pitch, flight path angle, power, flaps, airspeed, and to determine the parameters that would give the maximum flight path angle and the maximum rate of climb.
During the lab, we engaged the flaps, changed power settings as well as changed the pitch of the aircraft by deflecting the elevators. We found that as the pitch of the aircraft was increased, the airspeed decreased unless more power was applied. As the pitch increased, the airplane’s rate of climb increased as long as there was enough airspeed to keep the airplane from stalling. We did not experience any stalls. To determine the effects of the flaps, the flaps were engaged at 6000 ft. The airplane did two things. The pitch increased, and the speed decreased. The flaps not only increased the lift of the aircraft, they created more drag and therefore decreased the airspeed. In order to compensate for the increase in pitch, the nose had to be pushed down in order to maintain a zero rate-of-climb.
The trim of the aircraft enables the pilot to relax pressure on the yoke. Since the airplane will require a constant elevator deflection for a steady climb rate, the pilot would have to maintain the elevator’s position for the duration of the flight. In order to make life easier for the pilot, small tabs, called trim tabs, are deflected which allow the elevators to be at their rest position while still producing the required moment for a certain maneuver.
The maximum rate-of-climb and the maximum flight path angle were determined by fitting a second order polynomial to the data. Matlab was used in order to find the coefficients of the polynomial which is shown below:
(1)
Once the coefficients were found, the maximum rate-of-climb was calculated from the following equation:
(2)
Solve for v and plug back into Eq[1]. V was found to be 84 knots and max R/C was calculated to be 650 ft/min. The maximum flight path angle was also calculated from Eq[1].
(3)
The derivative of Eq[3] was calculated to be
(4)
To find max gamma, we solved for v and plugged it back into Eq[3]. The maximum flight path angle was found to be 6.5 degrees.
Experimental Data/Test Results
The following figure shows the flight profile for the experiment. The flight consisted of take-off and a climb to 6000 ft. A small cruise time was required in order to study the effect of the flaps on the flight characteristics of the airplane. The flight was concluded with a descent and landing.
Figure 1: Flight Profile for Lab Experiment. Flight plan included take-off, cruise, and descent.
The rate-of-climb and the airspeed of the aircraft for the portion of the flight up to 6000 ft are located in the following table
Table 1: Rate of Climb for Given Airspeed
Rate of Climb (ft/min) / Airspeed (knots)800 / 100
850 / 120
350 / 80
350 / 70
0 / 175
These data show that as airspeed decreases, the rate-of-climb will decrease unless the airplane is in straight-and-level flight. In other words, if the flight path angle is greater than zero, the airplane must go faster in order to climb faster.
The next figure is a plot of the rate-of-climb versus the airspeed of the aircraft. The data were fitted with a second order polynomial and the maximum rate of climb and the maximum flight path angle were calculated from the equation of the curve fit.
Figure 2: Rate-of-climb vs. airspeed. The equation of the quadratic curve fit is present in the figure as well as the points of maximum flight path angle and maximum rate-of-climb
Conclusions
The final conclusions are as follows:
1. There is a maximum flight path angle at which the Bonanza should fly in order to achieve the desired altitude in the shortest amount of distance. The maximum flight path angle is 6.5 degrees.
2. There is a maximum rate-of-climb at which the Bonanza should fly in order to achieve the desired altitude in the shortest amount of time. The maximum rate-of-climb is 650 ft/min.
3. Flaps increase lift, decrease airspeed, and cause a positive pitch rate on the aircraft. When engaging the flaps, the pilot must be prepared so as to counteract the positive pitch rate with a downward deflection of the elevators. Flaps are primarily used for landings because they allow the airplane to travel at slower speeds which are usually favorable for landings.
Recommendations
The only recommendations for this lab are as follows:
1. Test fly the aircraft before attempting to fly a strict flight plan because the simulator is extremely sensitive and takes a few minutes to get used to.
2. Determine what the best power settings are for each maneuver. Some of the maneuvers could not be accomplished with the prescribed power settings.
References
ASE 167M lab manual, Fall 2001 pp23-25.
Appendix A
Test Apparatus/Instrumentation
The simulator used during this experiment was a CAT II running Microsoft Flight Simulator 2000. The simulator is that of a Beechcraft Bonanza A-36.
Sample Calculations
The following is a sample calculation for the maximum rate-of-climb:
The following is a sample calculation for the maximum flight path angle: