Bu 131 Jungmann Spins Report

INTERNATIONAL TEST PILOT SCHOOL

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SPINS PERFORMANCE REPORT

ON

BÜCKER BÜ 131 JUNGMANN

BY

MAJ ROSLIMIZAL BIN KAMAROZAMAN RMAF

ITPS STUDENT

PREPARED FOR

CIVIL AVIATION AUTHORITY OF BORA-BORA

REPORT NO FTD090909

REVIEWED BY

MR GIORGIO CLEMENTI (ITPS PRESIDENT)

DATED

27 SEPTEMBER 2009


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SECTION 1. INTRODUCTION 1.1 BACKGROUND

The International Test Pilot School (ITPS) has been contracted to evaluate

the spinning characteristics of the Bücker BÜ-131 Jungmann aircraft. The request was originated by the Civil Aviation Authority of Bora-Bora which received an application from their local company to manufacture the subject aircraft. 1.2 PURPOSE OF THE TEST

The purpose of the test was to evaluate the spinning characteristics of the Bücker BÜ-131 Jungmann aircraft as an aerobatic aircraft against FAR Part 23 requirements for certification purposes.

1.3 MISSION DESCRIPTION

A local company of Bora-Bora was intended to manufacture an exact replica of Bücker BÜ-131 Jungmann as an aerobatic aircraft. 1.4 SCOPE AND CONDITIONS RELEVANT TO THE TEST 1.4.1 TEST AIRCRAFT

The test aircraft was the Bücker BÜ-131 Jungmann called C-FLAE owned by Mr Larry Ernewein. It was a two seat, bi-plane, wooden aircraft that built by the owner himself. The aircraft has a Tigre IVB, 4 in-line inverted cylinder piston engine with maximum of 150 hp. The empty weight was 1,050 lbs and maximum take-off weight was 1,650 lbs. The load factor of the aircraft was limited to +6g and -3g, while never exceed speed, VNE was 178 KIAS.

The weight and centre of gravity (CofG) of the aircraft during the test was

presented in Table I below and the weight and balance together with CoG position sheet was presented in Annex A.


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Flight Test Weight (lbs) Test CofG (In aft of datum)

First 1,557 22.18

Second 1,568 22.23

Table I. Aircraft Test Weight and Centre of Gravity

1.4.2 TEST VENUE

The test flights were took-off from the London International Airport, Ontario, Canada. The test was carried out at 5,000 of QNE, west of London. 1.4.3 TEST TEAM COMPOSITION

The ITPS Test Team consists of the following members:

a. Major Roslimizal bin Kamarozaman – Team Leader. b. Major Bruno Beeckmans – Project Test Pilot. c. Major Samsuri bin Abu Bakar – Engineer. d. Andrei Moise – Engineer.

1.4.4 TEST SCHEDULE AND TEST CONDITION In total, 6 sorties of flight test which accumulated 6.0 flight hours have been performed. The first 3 sorties were carried out as demonstration flight for the test team members. This allows the test team members to have an experience as well as better perspective of the spinning characteristics of the aircraft before 3 sorties of data flight. However, since the PFDR was found inoperative during the first data flight, only 2 data flights were investigated and analyzed. The overview of the flight programs that have been conducted was presented in Annex B.


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1.4.5 TEST TECHNIQUE 1.4.5.1 ERECT SPINS The aircraft was flown at stabilized altitude of 5,000 feet. The airspeed then was reduced gradually until aircraft experience normal stall condition. Rudder input was applied to the desired spin direction. Simultaneously, the control stick was pulled to fully aft position. As a result, the aircraft’s wing at desired spin direction fell and the aircraft officially entered the incipient spin phase. Approximately after 1 turn, the aircraft finally stabilized in fully develop spin phase. At selected number of turns, opposite rudder input was applied and followed by neutralization of the control stick. This action was called as a standard spin recovery technique. Approximately after 0.5 to 1 turn of recovery phase, the aircraft was observed safely recovered. However, for certification purposes, multiple recovery techniques were evaluated as presented in Table II below:

Test Points

Spin Entry Technique Spin Recovery Technique

1 Left rudder input, control stick fully aft

Standard spin recovery technique, 4 turns - right rudder - neutralized control stick

2 Right rudder input, control stick fully aft

Standard spin recovery technique, 4 turns - left rudder - neutralized control stick


2 turns - aileron against turn direction 4 turns - aileron neutral 5 turns - recovery


2 turns - aileron with turn direction 4 turns - aileron neutral 5 turns - recovery


3 turns - elevator neutral +1sec - rudder against - recovery


3 turns - controls release 4 turns - recovery

Table II. Type of spinning entry and recovery carried out


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The above test points were then reflected in the Test Card as attached in Annex C. 1.4.5.2 INVERTED SPINS The aircraft was flown at stabilized altitude of 5,000 feet. The aircraft was then positioned in inverted flight while gradually reducing the airspeed. Right before stall, left rudder input was applied and at the same time the control stick was push forward. The aircraft was then turned to the right in inverted condition. After 3 turns in fully develop phase, recovery phase was started by applying right rudder input and the control stick was released in neutral position. The inverted spins test point was also reflected in the Test Card attached in Annex C as Test Point 7. 1.4.6 TEST INSTRUMENTATIONS

In order to collect the spins data, KUTTA Personal Flight Data Recorder (PFDR) has been utilized. 1.4.7 REFERENCES The following documents have been referred during the conduct of the spinning assessment:

a. FAR Part 23

b. ITPS Stability and Control Manual.


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SECTION 2. RESULTS The results of the spinning flight test were presented in tabulated format in Annex D. In addition, the spin rate, roll rate, yaw rate, pitch rate and acceleration during the spin of first and second flight were presented in graphical format Annex E. The spin rate was obtained through application of this equation:

Spin rate, ω = √(Roll rate, p)2 + (Pitch rate, q)2 + (Yaw rate, r)2 Overall, the spinning characteristics from both flights have shown a similar

pattern in spin rate, roll rate, yaw rate, pitch rate and acceleration during the spinning as shown in Figure E1, E2, E3, E4 and E5 respectively. The data gathered proved that this aircraft portrayed predictable spin characteristics in every spin. 2.1 TEST POINT 1 – NORMAL SPIN TO THE LEFT

Test Point 1 was a standard spin exercise to the left with normal spin entry and recovery. The aircraft was stabilized at predetermined altitude of 5,000 feet. The airspeed was gradually bled until the aircraft reach the buffet condition. Prior to stall, the pilot applied full left rudder and pulled the stick aft simultaneously. The aircraft smoothly entered the incipient phase within 1 turn without any oscillation. The fully developed spin phase was observed stable with average spin rate recorded was 190 deg/sec for the first flight and 210 deg/sec for the second flight. The maximum load factor for both flights was +1.58g and maximum airspeed during the spin was between 52 to 55 KIAS which met the FAR Sec. 23.221, Paragraph C (2) requirement. The spin rate was stable and there was no extreme oscillatory motion during the fully developed spin phase. These criteria were met the FAR Sec. 23.221, Paragraph C (4) requirement. The normal recovery process was initiated right after 4 fully developed spin by applying right rudder and followed by centralization of the control stick. The aircraft was managed to recover within ½ turn in 2 seconds after initiation of the recovery actions with total height lost of 1,200 feet. Throughout any of the spin phase, it was observed that there was no tendency to enter the unrecoverable spin which met the FAR Sec. 23.221, Paragraph C (4) requirement. Therefore it was concluded an average aerobatic pilot will not encounter any difficulty to exercise the spin and able to exit the spin with the normal recovery procedures.


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2.2 TEST POINT 2 – NORMAL SPIN TO THE RIGHT

Test Point 2 was a standard spin exercise to the right with normal spin entry and recovery. Average spin rate recorded was 175 deg/sec for the first flight and 220 deg/sec for the second flight. The aircraft was managed to recover within 0.8 turn in 2 seconds after initiation of the recovery actions. The average airspeed during the spinning was between 50 to 70 KIAS while the highest acceleration during the spinning was +1.86g. 2.3 TEST POINT 3 – AILERON INPUT AGAINST SPIN DIRECTION

Test Point 3 was carried out with normal spin entry. Aileron input against spin direction was applied to simulate misapplication recovery method by any average pilot. Practically, it was observed that once input (aileron against spin direction) has been made, the spin rate was increased. However, the data from the PFDR revealed that there was no significant increase of the spin rate as shown in Figure E1. Instead, the yaw rate was drastically increased approximately 45% as shown in Figure E3. Meanwhile, the average roll rate was found dropped to 0 as presented in Figure E2.

The phenomena of increasing in yaw rate and decreasing in roll rate has

maintained the average spin rate to the normal rate. Even though with misapplication of aileron control, the aircraft was found still controllable and recovery is easy to obtain with normal recovery method. Recovery was made within 1 turn in 2 seconds. The average airspeed during the spinning was between 50 to 60 KIAS while the highest acceleration during the spinning was +1.43g. 2.4 TEST POINT 4 – AILERON INPUT WITH SPIN DIRECTION

Test Point 4 was carried out with normal spin entry. Aileron input to the spin direction was applied to simulate misapplication recovery method by any average pilot. Practically, it was observed that once input (aileron with spin direction) has been made, the spin rate was slightly increased. However, the data from the PFDR revealed that there was no significant increase of the spin rate as shown in Figure E1. Instead, the roll rate was found slightly increased as shown in Figure E2. Again, the aircraft was also found controllable and recovery is easy to obtain with normal recovery method. Recovery was made within 1 turn in 2 seconds. The average airspeed during the spinning was between 48 to 52 KIAS while the highest acceleration during the spinning was +2.17g.


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2.5 TEST POINT 5 – RUDDER INPUT AGAINST SPIN DIRECTION

Test Point 5 was carried out with normal spin entry. During recovery, the recovery aileron was released to neutral position while applying rudder input against the spin direction. Practically, there was no significant different observed compared to the normal recovery method. The aircraft was recovered within 0.5 turn in 1 second. The average airspeed during the spinning was between 58 to 64 KIAS while the highest acceleration during the spinning was +1.84g.

2.6 TEST POINT 6 – ALL CONTROLS RELEASE

Test Point 6 was carried out with normal spin entry. All controls were released for recovery to simulate pilot in disorientation or incapacitation. Practically, it was observed that the aircraft was reluctant to remain in spin condition. Once the controls were released, the aircraft tend to recover by itself. Through PFDR data, the aircraft was found recovered within 0.6 turn in 2.5 seconds. The average airspeed during the spinning was between 46 to 64 KIAS while the highest acceleration during the spinning was +1.45g. 2.7 TEST POINT 7 – INVERTED SPINS

Test Point 7 was carried out with normal inverted spin entry and recovery. Average roll rate and yaw rate during inverted spin was low compare to erect spin as shown in Figure E2 and E3 respectively. This resultant in lower spin rate as well, as shown in Figure E1. The aircraft was managed to recover within 0.5 turn in 1.5 seconds after initiation of the recovery actions. The average airspeed during the spinning was between 72 to 80 KIAS while the highest acceleration during the spinning was -2.20g.


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SECTION 3. CONCLUSION Based on flight tests that have been carried out, the Bücker BÜ-131 Jungmann can be categorized as an aerobatic aircraft. The insipient phase was predictable, standard and smooth as well as the recovery phase. The fully develop spin phase was stable with airspeed during the spinning was never exceeded the VMO of 178 KIAS and the acceleration during the spinning was never exceeded the design load factor of +6g and -4g. Despite of any misapplication of flight control, the aircraft remained controllable and the recovery phase was easy to obtain even with no action at all. There was no special recovery method to be developed for this aircraft to recover from the spinning condition. In case of the average skill pilot inadvertently enter the spin and in worst case scenario inadvertently apply any of flight control input, the aircraft still can be recovered just by releasing all flight controls and pull up once the spin stopped. The aircraft was found reluctant to remain in spinning condition and the recovery phase was found never exceeded 1.5 turns in any case.

Unfortunately, due to time constraint and operational limitations, the following requirements requested by the FAR Part 23 (in aerobatic category) have not been demonstrated:

a. Spin up to and including 6 turns spin with no more than additional 1.5 turns of recovery phase as requested in FAR Part 23, Subpart B, Sec. 23.221, Paragraph C (1). b. Spin with various power control setting and the aircraft must be impossible to obtain unrecoverable spins as requested in FAR Part 23, Subpart B, Sec. 23.221, Paragraph C (3). Despite of above, the flight test scope has concluded that the Bücker BÜ-

131 Jungmann met the FAR Part 23, Subpart B, Sec. 23.221, Paragraph C requirements.


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SECTION 4. RECOMMENDATION Even though the test flights were successfully conducted, the data gathered was not sufficient to be used for certification purposes. Therefore, it was recommended that a full spin matrix test is to be performed. The spin matrix test should cover the following: a. Spin up to and including 6 turns spin with no more than additional

1.5 turns of recovery phase. b. Spin with various power control setting.

c. Repeated spins to the left/right for all test points. d. Spin demonstration in most aft CofG condition. e. Spins demonstration in most forward CofG condition.

f. Power on at the spin entry. g. Power left on during the spin.

ANNEXES: A. Weight and Balance with Centre of Gravity Sheet. B. Spinning Flight Test Program. C. Spinning Test Card. D. Tabulated Spinning Flight Test Result. E. Graphical Spinning Flight Test Result.


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ANNEX A: WEIGHT AND BALANCE WITH CENTRE OF GRAVITY SHEET OF C-FLAE

Item W [lbs] W [kg] Arm MomentBasic airplane 1,050 18.3 19,194Pilot 165 75 57.1 9,441Copilot 187 85 28.3 5,303Seat 3 0 0 0.0 0Seat 4 0 0 0.0 0Seat 5 0 0 0.0 0Seat 6 0 0 0.0 0Oil 13 6 -4.7 -62Baggage 1 0 0 3.5 0Baggage 2 0 0 82.3 0Payload 366 166

ZFW 1,416 642

Fuel 141 64 5 663Total 1,557 22.18 34,539CG Limitation (17.3 - 24.8)

TAKE-OFF, FIRST FLIGHT

Item W [lbs] W [kg] Arm MomentBasic airplane 1,050 18.3 19,194Pilot 165 75 57.1 9,441Copilot 198 90 28.3 5,615Seat 3 0 0 0.0 0Seat 4 0 0 0.0 0Seat 5 0 0 0.0 0Seat 6 0 0 0.0 0Oil 13 6 -4.7 -62Baggage 1 0 0 3.5 0Baggage 2 0 0 82.3 0Payload 377 171

ZFW 1,427 647

Fuel 141 64 5 663Total 1,568 22.23 34,851CG Limitation (17.3 - 24.8)

TAKE-OFF, SECOND FLIGHT


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ANNEX B: SPINNING FLIGHT TEST PROGRAM

Date Mission Aircraft Pilot Co-Pilot FTE

Choke-out

time

ZULU

Take-off time

ZULU

Landing time

ZULU

Choke-in time

ZULUFlight Hours

09-Sep-09Erect and Inverted Spin

Demo Flight

BU 131 Jungmann -C-

FLAELarry Rosli Nil 1250 1256 1355 1404 0:59


Demo Flight

BU 131 Jungmann -C-

FLAELarry Samsuri Nil 1437 1443 1541 1546 0:58


Demo Flight

BU 131 Jungmann -C-

FLAELarry Andrei Nil 1625 1631 1733 1738 1:02

09-Sep-09Erect and Inverted Spin Data

Flight

BU 131 Jungmann -C-

FLAELarry Rosli Nil 2021 2028 2125 2131 0:57


Flight

BU 131 Jungmann -C-

FLAELarry Samsuri Nil 1223 1231 1331 1338 1:00


Flight

BU 131 Jungmann -C-

FLAELarry Andrei Nil 1548 1553 1650 1654 0:57


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ANNEX C: SPINNING TEST CARD

TPSpin to

doVi

EntryVi

Spin FuelAlt

StartAltEnd Profile

1 4LEFT

4 turns - recover

2 3RIGHT

3 turns - recover

35

LEFT

2 turns - aileron against4 turns - aileron neutral5 turns - recovery

45

LEFT

2 turns - aileron with4 turns - aileron neutral5 turns - recovery

54

LEFT

3 turns - elevator neutral+1sec - rudder against - recovery

64

LEFT

3 turns - controls release4 turns - recovery

TP Spin to do

Vi

EntryVi

SpinFuel Alt

StartAltEnd

Profile

73

RIGHT Inverted Spins

Landing TimeTake-off Time

Flight Setup Stabilize at 5,000 ft AGL. Bail out min 2,000 ft AGL

Take-off Weight

Bü-131 Jungmann

Larry

Aircraft Type

Pilot Andrei, Rosli, Sam

Date

FTE

C of G

Sept 2009

Recovery condition

Flight Setup Stabilize at 5,000 ft AGL. Bail out min 2,000 ft AGL

FT Technique

TEST CARD 2: INVERTED SPINS

Enter inverted stall and prepare to spin. Entry: PCL idle, push stick forward, apply left rudder.

Recovery: PCL idle, apply opposi te rudder, nuetral ize stick.

TEST CARD 1: ERECT SPINS

FT TechniqueAfter stabilization, trim at 1.3Vs, decelerate 1 kts/sec until Vs.

Standard Entry: PCL idle, pull stick aft, apply left or right rudder.Standard Recovery: PCL idle, apply opposite rudder, neutralize stick.

Recovery condition remarks


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ANNEX D: TABULATED SPINNING FLIGHT TEST RESULT

FIRST FLIGHT (SAMSURI)

TP Type of

Input No of Turns

Turn Direction

Average Roll

Rate, p (deg/sec)

Average Pitch

Rate, q (deg/sec)

Average Yaw

Rate, r (deg/sec)

Average Spins

Rate, Ω (deg/sec)

Average Airspeed During Spin

(KIAS)

Type of Recovery

No of Turns to Recover

Elapse Time to Recover

(sec)

Acceleration During Spin

(g)

1 Normal erect spins

4 Left 25 160 100 190 55 Normal 0.5 1 +1.57


3 Right 50 150 80 175 70 Normal 0.3 0.5 +1.61


5 Left 0 130 150 240 50

Aileron against the turn, then

neutral and recover

0.7 2 +1.22


5 Left 80 180 100 220 52

Aileron with the turn,

then neutral and recover

1.0 2 +1.96


4 Left 15 190 75 220 58

Elevator neutral, rudder

against the turn

0.3 1 +1.84


4 Left 20 160 15 160 64 Controls

release and recover

0.5 2 +1.15

7 Normal inverted

spins 3 Right 10 130 60 125 80 Normal 0.5 1 -2.20


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SECOND FLIGHT (ANDREI)

TP Type of

Input No of Turns

Turn Direction

Average Roll

Rate, p (deg/sec)

Average Pitch

Rate, q (deg/sec)

Average Yaw

Rate, r (deg/sec)

Average Spins

Rate, Ω (deg/sec)

Average Airspeed During Spin

(KIAS)

Type of Recovery

No of Turns to Recover

Elapse Time to Recover

(sec)

Acceleration During Spin

(g)


4 Left 55 175 100 210 52 Normal 1 2 +1.58


3 Right 75 170 95 220 50 Normal 0.8 2 +1.86


5 Left 0 165 140 200 60

Aileron against the turn, then

neutral and recover

1 1.5 +1.43


5 Left 55 175 75 200 48

Aileron with the turn,

then neutral and recover

0.6 1.5 +2.17


4 Left 20 205 90 225 64

Elevator neutral, rudder

against the turn

0.5 1 +1.77


4 Left 0 120 40 140 46 Controls

release and recover

0.6 2.5 +1.45

7 Normal inverted

spins 3 Right 10 120 75 150 72 Normal 0.5 1.5 -2.00


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ANNEX E: GRAPHICAL SPINNING FLIGHT TEST RESULT

Registration: C-FLAE Date: 10 Sept 2009

Configuration: N/A Gross weight range: 1,568 – 1,557 Lbs CoG: 22.18 – 22.23 in aft of datum Method: TP1 – TP6 = Normal Erect Spins

TP7 = Inverted Spins

0

50

100

150

200

250

300

0 1 2 3 4 5 6 7 8

Angular Rate (deg/s)

Test Points

Figure E1: Spin Rate vs. Testpoints

1st flight, 10 lbs lighter 2nd flight


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0

10

20

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7 8


Test Points

Figure E2: Roll Rate vs. Testpoints



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0

20

40

60

80

100

120

140

160

0 1 2 3 4 5 6 7 8


Test Points

Figure E3: Yaw Rate vs. Testpoints



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0

50

100

150

200

250

0 1 2 3 4 5 6 7 8


Test Points

Figure E4: Pitch Rate vs. Testpoints



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-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0 1 2 3 4 5 6 7 8

Acceleration (g)

Test Points

Figure E5: Acceleration vs. Testpoints


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Bu 131 Jungmann Spins Report

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