28 SEP 2009

DEPARTMENT OF THE AIR FORCE

HEADQUARTERS AIR FORCE CIVIL ENGINEER SUPPORT AGENCY

28 SEP 2009

FROM: AFCESA/CEO

139 Barnes Drive, Suite 1

Tyndall AFB, FL 32403-5319

SUBJECT: Engineering Technical Letter (ETL) 09-1: Airfield Planning and Design

Criteria for Unmanned Aircraft Systems (UAS)

1. Purpose. This ETL provides guidance and criteria for planning and designing airfields that support operations of Department of Defense (DOD) UAS presently fielded or will be fielded by 2012.

2. Application: All DOD organizations responsible for planning and design of airfield pavements.

2.1.

Authority: Air Force policy directive (AFPD) 32-10, Air Force Installations and

Facilities.

2.2.

Coordination:

•

Major command (MAJCOM) pavement engineers

•

HQ Air Force Center for Engineering and the Environment (AFCEE/TD)

•

HQ Air Force Flight Standards Agency (AFSSA/A3A, AFSSA/A3I)

•

HQ Air Combat Command (ACC/A3YU, ACC/A8U1)

•

UAS system program offices (SPO) and program executive offices (PEO)

2.3. Effective Date: Immediately. This ETL will remain in effect until these findings are incorporated into joint-Service pavement doctrine and similar technical guidance.

2.4. Intended Users:

•

Air Force Prime BEEF and RED HORSE units.

•

Army Corps of Engineers.

•

Navy NAVFAC offices and Seabee units, and Marine Corps combat engineer units.

•

Construction contractors building and expanding DOD airfields.

•

Other organizations responsible for airfield construction.

3.

References.

3.1. Air Force:

•

Technical Manual 1Q-4(R)A-2-DB-1, 22 April 2008, Version 07.12.001,

RAC#7, Global Hawk Technical Orders , 303d AESG/LG, WPAFB, OH 45433,

DSN 785-3473.

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

•

Flight Manual TO 1Q-1(M)B-1, MQ-1B and RQ-1B Systems , 1 November

2003, Change 8, 22 January 2007, Det 3, 658 AESS, 16761 Via Del Campo

Court, San Diego, CA 92127.

•

Flight Manual TO 1Q-9(M)A-1, USAF Series MQ-9A Aircraft , 20 February

2007, Change 1 – 30 April 2007, Det 3, 658 AESS, 16761 Via Del Campo

Court, San Diego, CA 92127.

•

Engineering Technical Letter (ETL) 08-6, Design of Surface Drainage

Facilities , 5 February 2008, HQ AFCESA, Tyndall AFB, FL 32403, http://www.wbdg.org/ccb/browse_cat.php?o=33&c=125

3.2. Navy:

•

A1-MQ8BA-NFM-000, NATOPS Flight Manual, Navy Model MQ-8B,

Unmanned Aerial Vehicle , Program Executive Office - Unmanned Aviation &

Strike Weapons, PEO (U&W) PMA-266, Multi-Mission Tactical Unmanned Air

Systems, 22707 Cedar Point Road, Building 3261, Patuxent River, Maryland

20670-1547.

3.3. Army:

•

Engineering and Construction Bulletin (ECB) 2008-15, Design of Surface

Drainage Facilities , 22 April 2008, Directorate of Civil Works, Washington

D.C., http://www.wbdg.org/ccb/browse_cat.php?o=31&c=214

•

Technical Manual (TM) 9-5895-XXX-10, Operator’s Manual for Shadow 200

TUAV System with RQ-7B Air Vehicle , 27 August 2004, US Army Aviation and Missile Command, ATTN: Unmanned Aerial Vehicle System, ATTN:

SFAE-AV-UAV, Redstone Arsenal, AL 35898.

•

Unified Facilities Criteria (UFC) 3-230-06A, Subsurface Drainage , 16 January

2004, http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

3.4. Joint:

•

Pavement-Transportation Computer Aided Structural Engineering (PCASE)

• design and evaluation computer program, http://www.pcase.com/

UFC ,

• http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

UFC , http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

4. Acronyms.

ACN – Aircraft Classification Number

ASC/658 AESG – Aeronautical Systems Center, 658 Aeronautical Systems Group

CBR

DOD

ETL

– California Bearing Ratio

– Department of Defense

– Engineering Technical Letter

2

GCS

GDT

– ground control station

– ground data terminal k – modulus of subgrade reaction

NAVFAC

PCASE pci

PCN

PGCS

PGDT

– Naval Facilities Engineering Command

– Pavement-Transportation Computer Aided Structural Design and

Evaluation

– pound per cubic inch

– Pavement Classification Number

– portable ground control station

– portable ground data terminal

– Priority Improved Management Effort - Base Engineer Emergency Prime BEEF

Force psi psig

RCR

– pound per square inch

– pound per square inch gauge

– Runway Condition Rating

RED HORSE– – Rapid Engineers Deployable Heavy Operations Repair Squadron

Engineers

TALS – Tactical Automated Landing System

TDP

UAS

– touchdown point

– unmanned aircraft systems

UPS – uninterruptible power supply

5. Definitions.

5.1.

Pass.

The movement of an aircraft over a specific spot or location on a pavement feature.

5.2.

Sun Screen . A cover to protect aircraft from the sun’s ultraviolet rays.

6. Aircraft Characteristics. Table 1 lists aircraft covered in this ETL. Tables 2 through

7 list each aircraft’s dimension, weight, and operational characteristics.

Table 1. Aircraft by Service

Service Aircraft

RQ-4A/B Global Hawk

Air Force

Army

MQ-9A Reaper

RQ-1B/MQ-1B Predator

RQ-7B Shadow 200

MQ-1C ERMP Warrior

Navy/Marine Corps

MQ-8B Fire Scout

RQ-4B Global Hawk

3

Table 2. RQ-4 Global Hawk

(See Figures 1 through 4)

RQ-4A RQ-4B

Wing Span (ft)

Length (ft)

Height (ft)

Vertical Clearance (in)

Tread (ft)

Wheel Base (ft)

Pivot Point (ft)

Aircraft Turning Radius (ft)

Controlling Gear

180° Turn (ft)

Basic Empty Gross Weight (lbs)

Basic Mission Take-Off Weight (lbs)

Basic Mission Landing Weight (lbs)

Max Landing Gross Weight (lbs)

Take-Off Distance, Ground Roll (ft)

Take-Off Distance, to 50-ft (ft)

116.2

44.4

15.2

19.5

10.6

14.8

75

67

Main

133

3,500

4,300

11,900

26,750

12,900

26,500

130.9

47.6

15.4

21.1

15.4

20.7

97

20.65

31.24

Main

15,317

32,190

16,325

32,250

4,800

5,800

Landing Distance, Ground Roll (ft)

Landing Distance, from 50-ft (ft)

Assembly Configuration

% of Gross Load on Assembly

8,000

See Note

Twin Tricycle

88.5% on Main

7,800

See Note

Single Tricycle

89.5% on Main

Tire Pressure, Nose Gear (at Max T/O weight) 88-98 psig 109-119 psig

Tire Pressure, Main Gear (at Max T/O weight) 201-206 psig 289-299 psig

Note: Not applicable since block 10 (RQ-4A) typically flares between 45 ft (Above

Ground Level [AGL]) to 55 ft (AGL) over the runway. The flare initiation altitude is a function of sink rate. Mission planners build landing approach for a 4.5 degree glide slope (with engine on) and 5.25 degree (engine out). They survey the area for terrain and obstacle clearance required to safely fly on the glide slope autonomously.

4

Wing Span (ft)

Length (ft)

Height (ft)


Tread (ft)

Wheel Base (ft)

Pivot Point (ft)


Table 3. MQ-9A Reaper

(See Figure 5)

66

36.2

11.8

20

12

10.2

32 to inside wing tip

98 to outside wing tip;

71 to outside wheel

Main Controlling Gear

180° Turn (ft)







196

4,900

10,500

8,500

10,500

3,450

3,600





Tire Pressure, Nose Gear (at Max T/O weight)

Tire Pressure, Main Gear (at Max T/O weight)

4,375

5,000

Single Tricycle

90% on Main (assumed)

80 psig

170 psig

5

Wing Span (ft)

Length (ft)

Height (ft)


Table 4. RQ-1B/MQ-1B Predator

(See Figures 6 and 7)

48.7

(MQ-1B Block 10 &15 is 55.25)

27.0

6.9

5.3

Tread (ft)

Wheel Base (ft)

Pivot Point (ft)

9.1

10.2

TBD


Controlling Gear

180° Turn (ft)


TBD

Main

196

1,680

(1,760 with Ice Protect System)

2,250 Basic Mission Take-Off Weight (lbs)







TBD

TBD

1,800

2,500

1,150

1,700



Single Tricycle


Tire Pressure, Nose Gear (at Max T/O weight) 45±2 psig

Tire Pressure, Main Gear (at Max T/O weight) 50±2 psig

6

Table 5. MQ-1C ERMP Warrior

Wing Span (ft)

Length (ft)

Height (ft)


Tread (in)

Wheel Base (in)

Pivot Point (ft)


Controlling Gear

180° Turn (ft)









56.3

27.5

(29 with Alpha Probe attached)

9.9 - Level

(10.32 - for uneven surfaces, allow for an additional 5 inches)

TBD

TBD

TBD

TBD

97.5

Main

TBD

TBD

2,250

TBD

3,200

TBD

TBD

TBD

1,700



Single Tricycle

Tire Pressure, Nose Gear (at Max T/O weight) 45±5 psig


Tire Pressure, Main Gear (at Max T/O weight) 50±5 psig

7

Wing Span (ft)

Length (ft)

Height (ft)


Tread (in)

Wheel Base (in)

Pivot Point (ft)


Table 6. RQ-7B Shadow 200

14

11.33

3.2

TBD

TBD

TBD

TBD

TBD

Controlling Gear

180° Turn (ft)










Main

TBD

TBD

TBD

TBD

TBD

TBD

TBD

252 to 257

370 to 375

Single Tricycle

% of Gross Load on Assembly 95% on Main (assumed)

Tire Pressure, Nose Gear (at Max T/O weight) TBD

Tire Pressure, Main Gear (at Max T/O weight) 35+1 psig

8

Table 7. MQ-8B Fire Scout

(See Figure 8)

Max Length (Main rotor Spread, tail rotor vertical) (ft)

Length (nose to tail, main rotor folded over tail, tail rotor vertical) (ft)

31.67

23.25

Length (nose to tail rotor horizontal)(ft)

Width (outer diameter of skid tubes) (ft)

24.73

6.2

Height of main rotor blades (ground to flat rotor disc) (ft) 8.92

Height of vertical stabilizer antenna (ft) 9.75

Main rotor diameter (ft) 27.71

Tail rotor diameter (ft) 4.25

Ground clearance (fuselage, Water Line to ground) (in) 21

Ground clearance (tail skid) (ft)

Turning Radius in tow (ft)

3.25

20

Maximum gross take-off weight (lbs)

Maximum towing weight (lbs)



3,150

3,150

2,029

Skid tubes

5.2. Aircraft Classification Numbers.

The International Civil Aviation Organization

(ICAO) has developed and adopted a standardized method of reporting pavement strength for conventional rigid and flexible pavements. The procedure is known as the Aircraft Classification Number/Pavement Classification Number (ACN/PCN). The

ACN is a number that expresses the effect an aircraft will have on a pavement. The

PCN is a number that expresses the capability of a pavement to support aircraft operations. The ICAO manual specifies that the bearing strength of a pavement intended for aircraft of mass greater than 5,700 kg (12,500 lbs) shall be made available using the ACN/PCN method. Therefore, the Global Hawk is the only UAS aircraft that will be included. Figures 9 and 10 are ACN relationships for the Global

Hawk on flexible and rigid pavements respectively.

9

Figure 1. RQ-4A Global Hawk Dimensions

10

*(Diameter)

Figure 2. RQ-4A Clearances and Turning Radii

11

Figure 3. RQ-4B Dimensions

12

FEET MINIMUM

TURNING WIDTH

*RADII

Figure 4. RQ-4B Clearances and Turning Radii

13

Figure 5. Dimensions of MQ-9A Reaper

14

Figure 6. Dimensions of RQ-1 B Predator

15

Figure 7. Dimensions of the MQ-1B Predator

16

Figure 8. Dimensions of the MQ-8B Fire Scout

17

RQ4-B GLOBAL HAWK

15

14

13

12

11

10

9

8

7

6

15

A

20 25 30

Aircraft Gross Weight, (kips) Flexible Pavement

35

Load (kips)

15.3 MIN

32.3 MAX

ACN Value for each Flexible Subgrade Category (CBR, %)

A (> 13) B (>=8 - <=13) C (>=4 - <8) D (< 4)

6.5

13.7

6.5

13.7

6.5

13.7

6.5

13.7

Figure 9. ACN for RQ4-B Global Hawk on Flexible Pavement

18

RQ4-B GLOBAL HAWK

15

14

13

12

11

10

9

8

7

6

15

A

20 25 30

Aircraft Gross Weight, (kips) Rigid Pavement

35

Load (kips)

15.3 MIN

32.3 MAX

A (> 400)

ACN Value for each Rigid Subgrade Category (k, pci)

B (>=200 - <=400) C (>=100 - <200) D (< 100)

6.9

14.8

6.9

14.8

6.9

14.8

6.9

14.8

Figure 10. ACN for RQ4-B Global Hawk on Rigid Pavement

19

6. Dimensional Criteria. This section presents design considerations for UAS airfields.

These criteria are provided as a supplement to the criteria given in UFC 3-260-01,

Airfield and Heliport Planning and Design .

6.1. Runway and Overrun Descriptions.

Criteria presented in UFC 3-260-01 will be used. Only exceptions for UAS will be identified herein. The Global Hawk requires a

Class B airfield as defined in UFC 3-260-01. The Reaper, Predator, and ERMP require a Class A airfield, with some noted exceptions due to support equipment that must be in close proximity to the airfield. Criteria for the Shadow 200 and the Fire

Scout are included in this ETL.

6.1.1. Global Hawk. Takeoff distances are a function of the engine thrust, runway slope, runway condition rating, takeoff gross weight, temperature and pressure altitude and wind. Landing distances depend on brake rate, gross weight, temperature and pressure altitude, runway condition rating, runway slope, spoilers, and wind. Runway length requirements for the RQ-4A Global Hawk can be calculated from the following figures. Figure 11 gives the density ratio as a function of the temperature and pressure altitude at the runway site. Figures 12 to 15 give the landing distance as a function of density ratio, wind, and runway slope. Takeoff distances are shown in Figure 16 as a function of density ratio, wind, and runway slope. Performance data for the RQ-4B is being developed and not available.

Example of calculation of runway length requirements for RQ-4A Global Hawk:

Given:

Pressure Altitude = 4,000 ft.

Average high temperature for warmest month = 89º F

Gross Weight of Aircraft = 26,500 lbs

Wind= 0 knots

Runway Slope= 1% uphill

Brake Rate= 8 ft/sec

Runway Condition Rating = 15 (wet)

From:

Figure 11 – Density Ratio = 0.81

Figure 13 – Corrected landing distance - touchdown waypoint to stop =

9,400 ft.

Figure 16 – Corrected takeoff ground run = 5,000 ft.

Runway length requirement would be 10,000 ft. This could be shortened since the aircraft will not likely land at maximum weight.

20

Runway width requirements are related to navigation quality, which is a rating of signal strength as determined by system site selection and communications personnel. The theoretical runway width requirements for operations at various navigational quality values are shown in Table 8. For operations from a typical

150-foot-wide runway, the minimum required navigation quality is 17. (Note: A navigational quality of 17 is always considered the minimum for takeoffs, regardless of the actual runway width.) As the widest runway likely to be encountered is 300 feet, a minimum navigational quality of 15 would be required for landings. When navigation quality values are degraded to less than required for the available runway width, an alternate landing site, such as a dry lakebed or unoccupied auxiliary airfield, should be identified as a safe alternative.

Table 8. Theoretical Runway Width Requirements

Navigation Quality

Theoretical Runway Width (ft)

Requirements

18 148

17 148

16 208

15 268

14 328

13 388

12 448

Another exception to the Class B runway requirements is the longitudinal slope.

Runway slope limits apply to constant slope runways. The slope on downhill runways could match or exceed the flare sink rate, causing excessive flare distance and possible runway departure. The slope on uphill runways could limit flare distance, causing a hard landing. For takeoffs and landings, the maximum uphill slope is 1.0%. For landings, the maximum downhill slope limits vary with gross weight, ranging from 0.25% to 0.5% with decreasing gross weight, as indicated in Figures 12 thru 14.

21

Figure 11. Density Ratio from Temperature and Pressure Altitude

22

Figure 12. RQ-4 Landing Distance for 4 Ft/Sec Brake Rate

23


24


25

Figure 15. RQ-4 Landing Distance for 12 Ft/Sec Brake Rate with Override Selected

26

Figure 16. RQ-4 Takeoff Ground Run

27

6.1.2. Reaper, Predator and ERMP. Runway and overrun requirements for the

Reaper and Predator will conform to those of an Air Force Class A runway and the ERMP to those of an Army Class A runway as described in UFC 3-260-01.

6.1.2.1.

Reaper. Takeoff and landing figures for the MQ-9A Reaper are referenced to a Standard Day. A Standard Day is at a temperature of 59º F

(15º C). Figures 17 and 18 give the takeoff ground roll and correction for runway slope for a Standard Day. Figures 19 and 20 are for a takeoff ground roll for a Standard Day plus 30 °F. Figures 21 and 22 give landing distances and correction for runway slope for the MQ-9A.

Example of Runway Length calculation for MQ-9A Reaper:

Given:




Wind= 0 knots



From:

Figure 19 STD+30ºF (59ºF+30ºF=89ºF) Takeoff Ground Run= 5,600 ft.

Figure 20 Ground Roll with slope= 6,250 ft.

Figure 21 Landing Ground Roll = 4,950 ft.

Figure 22 Corrected Landing Ground Roll for Slope = 4,000 ft.

Runway length requirement would be 6,500 ft.

6.1.2.2. Predator. Takeoff and Landing figures for the RQ-1B/MQ-1B Predator are shown in Figures 23 to 26 with corrections for runway slope and Runway

Condition Rating (RCR).

Example of runway length requirement for MQ-1B Predator:

Given:




Wind= 0 knots



28

From:

Figure 11- Density Ratio = 0.81

Figure 23 Takeoff Ground Run = 3,600 ft.

Figure 24 Takeoff Ground Run with slope correction= 4,200 ft.

Figure 25 Landing Ground Roll = 1,360 ft.

Figure 26 Landing Ground Roll with corrections for Slope and RCR= 1,600 ft.

Runway Length requirement = 4,500 ft.

Note: For assistance with conditions other than those covered in Tables 17 through 27, contact:

ASC/658 AESG

Area B, Bldg 11

WPAFB, OH 45433

(937) 904-4536

PSS.MQ-9@wpafb.af.mil

6.1.2.3. ERMP. Performance data for the ERMP has not been developed.

Runway length and width requirements are 4,500 feet by 100 feet and should follow the criteria for a Class A Army airfield.

6.1.3.

Shadow 200. The launch and recovery site requires a clear, flat area, large enough for the required landing touchdown dispersion and runway length and width. The overall site consists of a rectangular area at least 450 feet long and

164 feet wide. In addition to the main rectangular area, an additional area on either side of the operating strip called the net run-out area is required. Each net run-out area is 100 feet long and 50 feet wide. This makes the operating surface with net run-out areas at least 650 feet long and 50 feet wide. The maximum length of the rectangular area is 1080 feet and the maximum length of the operating surface is 1280 feet (see Figures 27 and 28). The site should be aligned with the prevailing wind direction. Maximum permitted tail wind during landing is 5 knots. The overall site length includes at least 100 feet of rollout space beyond the barrier net. The rollout space shall be provided to permit air vehicle net arrestment without any obstacles or ruts larger than 2 inches in size.

The minimum overall site length may be reduced to 650 feet if the grade (slope) along the runway centerline is near zero. The runway direction slope may not exceed ± 1.7% grade within the entire runway and rollout space. The slope perpendicular to runway direction must also fall within the ± 1.7% grade. Typical layouts for the long field and short field are shown in Figures 27 and 28. In addition to runway dimension and grade restrictions, obstacle /terrain clearances must also be observed. Figures 29 and 30 describe the required clearances. All obstacle and terrain height restrictions are measured relative to the touchdown point (TDP) elevation.

29

6.1.4. Fire Scout. The Fire Scout is designed to be launched from a ship or from land. The Fire Scout can utilize any cleared area to launch and recover. The limited-use helipad (50 ft by 50 ft) described in UFC 3-260-01 is acceptable for this aircraft. Line of site in any launch and recovery area to the UHF/VHF antennas connected to the ground control station is mandatory. Performance and clearance requirements are being developed.

6.2.

Clear Zones, Accident Potential Zones, and Imaginary Surfaces.

The clearance and grade requirements for runways that support the UAS outlined in this ETL shall follow the requirements in UFC 3-260-01. For the Reaper and Predator, support infrastructure includes ground control stations (GCS), satellite communication links, ground data terminals (GDT), and associated equipment such as HVAC systems and generators. The GDT provides a line-of-sight communication link from the GCS to the aircraft and may create sighting issues requiring the need to apply for a permissible deviation per Attachment 14 of UFC 3-260-01.

30

Figure 17. MQ-9 Predator Takeoff Ground Roll for STD Day

31

Figure 18. Corrections for Runway Slope for MQ-9 on STD

32

Figure 19. Takeoff Ground Roll for MQ-9 on STD +30º F

33

Figure 20. Runway Slope Corrections for MQ-9 on STD + 30ºF

34

Figure 21. Landing Ground Roll for MQ-9.

35

Figure 22. Runway Slope Corrections for MQ-9 Landing Ground Roll

36

Figure 23. RQ-1B/MQ-1B Predator Takeoff Ground Run

37

Figure 24. RQ-1B/MQ-1B Runway Slope Correction on Takeoff Ground Roll

38

Figure 25. RQ-1B/MQ-1B Landing Ground Roll

39

Figure 26. RQ-1B/MQ-1B Landing Ground Roll Corrections for Slope and RCR

40

Figure 27. Shadow 200 Launch and Recovery Site (Long Field)

* The approach-direction distance from runway edge to TDP may be reduced from 160 ft to

100 ft if the approach terrain is of an appropriate grade. This will reduce the overall length from

710 ft to 650 ft and the runway length from 510 ft to 450 ft. See paragraph 6.1.3 for specific requirements. There is no limitation on the maximum approach-direction distance from runway edge to TDP.

Figure 28. Shadow 200 Launch and Recovery Site (Short Field)

41

From Figure 30 in this Region

Figure 29. Shadow Lateral Obstacle Clearances

42

Figure 30. Shadow Approach Obstacle Clearances

6.3. Taxiways and Aprons. The widths and turning radius of taxiways should conform to the Class B requirements for the Global Hawk and the Class A requirements for the Reaper, Predator, and ERMP.

6.3.1.

Global Hawk. Parking areas for the RQ-4A Global Hawk should be designed with dimensions shown in Figure 31. Layouts for the tie-downs for the

RQ-4A are shown in Figure 32. Parking areas for the RQ-4B Global Hawk should conform to dimensions shown in Figure 33. Locations for tie-downs on the

RQ-4B are shown in Figure 34 but specific dimensions for the tie-down point have not been provided. Tie-downs should be designed to resist an uplift force equal to the rated capacity of the tie down chain (i.e., typically 10,000 pounds).

Special apron areas for hot refueling or arming/disarming are not required for the

Global Hawk.

6.3.2.

Reaper and Predator. These UAS are typically parked under sun screens during daytime and in hangars at night and during severe weather, negating the need for tie-downs. As discussed in paragraph 6.2, support infrastructure for these systems must be sited in accordance with UFC 3-260-01.

43

Figure 31. Parking Area Dimensions for RQ-4A Global Hawk

44

Figure 32. Tie-Down Layout for the RQ-4A Global Hawk

45

Figure 33. Parking Area Dimensions for RQ-4B Global Hawk

46

Figure 34. Locations for Tie-Downs for RQ-4B Global Hawk

47

7. Structural Design Criteria.

7.1. Procedures for the structural design of airfields to support the UAS are presented in this section. These criteria are submitted as a supplement to that given in UFC 3-260-02, Pavement Design for Airfields . The proliferation of UAS throughout the DOD resulted in requiring the criteria to be updated to include these aircraft.

7.2. Procedures and requirements for site investigation; base, subbase, and subgrade; frost design; and stabilization should follow those outlined in UFC 3-260-

02. It is expected that the Global Hawk, Reaper, Predator, and ERMP will only operate on surfaced pavements. Design curves for both flexible and rigid pavements for the Global Hawk are shown in Figures 35 and 36. Designs for all other aircraft should follow the minimum thickness requirements for both rigid and flexible pavements as outlined in UFC 3-260-02. The PCASE program is recommended for detail design, but manual designs are as follows:

7.2.1. Flexible Pavement Example for Global Hawk:

Given:

Design Subgrade CBR – 6 percent

Aircraft Load – 32,250 pounds

Aircraft Pass Level – 10,000 passes

Enter Figure 35 at 6 CBR. Go vertically to the aircraft load of 32,250 pounds.

Go horizontally to 10,000 passes, then go vertically to read a 10.5-inch design thickness requirement.

From Table 8-5 of UFC 3-260-02, the minimum surface thickness is 4 inches over a 100 CBR base course and 5 inches over an 80 CBR base course.

Design with a 100 CBR base course would be:

4 inches of asphalt surface course

6.5 inches of 100 CBR base course

Compacted subgrade

Design with an 80 CBR base course would be:

5 inches of asphalt surface course

6.0 inches of 80 CBR base course (Minimum base thickness controls.)

Compacted subgrade

48

RQ4-B GLOBAL HAWK (Traffic Area A)

CBR

10 1 100

100

32250 lb s

25000 lbs

16000 lb s

100

Pa sse s

100

0 P ass es

100

00

Pas ses

10

1 10

Thickness, in

100

1

Figure 35. Flexible Pavement Design Curve for the RQ4-B Global Hawk

7.2.2. Rigid Pavement Design Example.

Given:

Design Flexural Strength of PCC – 640 psi

Design Modulus of Subgrade Reaction, k – 25 pci

Design Aircraft Load – 32,250 pounds

Design Pass Level – 10,000 passes

Traffic Area – A

Enter Figure 36 at a flexural strength of 640 psi. Move horizontally to k value of 25 pci. Move vertically to the aircraft load of 32,250 pounds. Move horizontally to the pass level of 10,000. Move vertically to Traffic Area A, then move horizontally to read a required design thickness of 8.5 inches.

The design would be 8.5 inches of PCC over a minimum of 4 inches of aggregate base course or that to meet minimum thickness for drainage layers as shown in UFC 3-230-06A, Subsurface Drainage .

49

RQ4-B GLOBAL HAWK (Traffic Area A)

1400

1300

1200

1100

1000

900

800

700

600

500

400

0

5

0

0

K

32

25

0 lb s

2

5

0

K

1

0

0

K

2

5

K s

25

00

0 lb

00 lb s

160

5 10 15 20 25

Traffic Area A

100 Passes

1000 Passes

10000 Passes

30 35

18

40

20

12

14

16

8

10

4

6

0

2

Figure 36. Rigid Pavement Design Curve for the RQ4-B Global Hawk

8. Point of Contact. Recommendations for improvements to this ETL are encouraged and should be furnished to the Pavements Engineer, HQ AFCESA/CEOA, 139 Barnes

Drive, Suite 1, Tyndall AFB, FL 32408-5319, DSN 523-6439, Commercial (850) 283-

6439, e-mail AFCESAReachbackCenter@tyndall.af.mil

.

LESLIE C. MARTIN, Colonel, USAF 1 Atch

Chief, Operations and Programs Support Division 1. Distribution List

50

DISTRIBUTION LIST

SPECIAL INTEREST ORGANIZATIONS

Information Handling Services

15 Inverness Way East

Englewood, CO 80150

(1) Construction Criteria Base

National Institute of Bldg Sciences

Washington, DC 20005

(1)

Atch 1

(1 of 1)

28 SEP 2009

RQ4-B GLOBAL HAWK

RQ4-B GLOBAL HAWK

Related documents

Products

Support

28 SEP 2009

RQ4-B GLOBAL HAWK

RQ4-B GLOBAL HAWK

Related documents

Add this document to collection(s)

Add this document to saved

Suggest us how to improve StudyLib