Purpose Amphibian Aircraft

1Sai Vinay Sandapeta, 2Sai Kiran Parre, 3A Sai Nikhil, 4Mariyada Vamshi Krishna Reddy, 5Saniya Moinuddin 1UG Student, 2UG Student, 3UG Student, 4UG Student, 5UG Student 1Department of Aeronautical Engineering, 1Insitute of Aeronautical Engineering, Hyderabad, India

Abstract : In this paper, we describe the conceptual design of an Amphibian aircraft which is capable of the multi-purpose missions (i.e. Passenger mission and Air-Sea Rescue mission). The aircraft is to be based and operated out of Juhu Airport (ICAO Code: VAJJ) in Mumbai. As India has more than 200 lakes, reservoirs, and ponds, several of which have the potential to be utilized for operation of amphibian aircraft. So, amphibious aircraft can be used as air transport services which could extensively improve connectivity between the islands and the mainland as they have a minimum of infrastructure requirement.

IndexTerms - Amphibian aircraft, Conceptual Design, Aircraft Design , FAR23 COMMUTER Aircraft.

1. INTRODUCTION An amphibious aircraft can be defined as an aircraft that can take off and land on either land or water. There are historically two classes of amphibious aircraft: flying boats and floatplanes. a. Pure Floatplane: A pure floatplane is defined as an aircraft which can only take off/land from/on water and derives its flotation from discrete floats. b. Amphibious Floatplane: An amphibious floatplane is defined as in ‘a’ above but is equipped with wheels to enable it to take off/ land from/on land in addition to water. (See in Fig 1)

Fig 1: Amphibious Floatplane c. Pure Flying boat: A pure flying boat is defined as an aircraft which can only take off/land from/on water and derives its flotation from a specially configured fuselage. d. Amphibious Flying boat: An amphibious flying boat is defined as in 'c’ above but is equipped with wheels to enable it to take off/land from/on land in addition to water. (See in Fig 2)

Fig 2: Amphibious Flying boat

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In the general aviation (GA) field, amphibian aircrafts have always occupied a small but important niche in the marketplace, used primarily for operations into and out of remote areas where lakes were more plentiful than airports. India has more than 200 lakes, reservoirs and ponds, several of which have the potential to be utilized for operation of amphibian aircraft. Several cities along India’s coastline and in the Lakshadweep and Andaman and Nicobar Islands do not have access to much airport infrastructure. Air transport services could extensively improve connectivity between the islands and the mainland. Since the coast and the islands have access to large bodies of water, amphibious aircraft can be used as they have a minimum of infrastructure requirement. Aside from civilian operations, the scope of military applications is also immense for an amphibious aircraft such as Air-Sea Rescue (ASR) and littoral warfare operations. Today, most such aircraft tend to be ‘floatplanes’, aircraft originally designed for land operation to which have been added rather large floats to replace the conventional wheeled undercarriage. Such aircraft are usually considerably slower in flight and more limited in performance than their original designs due to the added weight and drag of the floats. In attempts to get better overall performance, a few specialty aircraft have been designed as amphibians with a hull fuselage. However, the compromises required to allow both land and water operations have still resulted in added weight and complexity, and a lower cruise speed than conventional land-based aircraft designs.

2. PROBLEM STATEMENT To design of an amphibian aircraft which is capable of multiple missions, viz., Passenger mission (Pax) and Air-Sea Rescue (ASR) mission. The aircraft is to be based and operated out of Juhu Airport (ICAO Code: VAJJ) in Mumbai. The Pax mission would involve two daily return flights to Pavana Lake (Ref. Fig 3). The ASR mission would involve a three hour search over the off- shore rigs located in the DCS Block and Panna-Bassein Blocks of Bombay High Oilfield (Ref. Fig 4).

Fig 3: Passenger mission (Pax) mission Fig 4: Air-Sea Rescue (ASR) mission

3. REQUIREMENTS These are requirements identified as per missions which follows as :

Table 1. Requirements

S.No Critical Requirement Desired Feature

1. Airport ICAO CODE VAJJ

2. DESIGN CODE FAR 23 COMMUTER

3. Payload weight 1225kgs

4. Seat Configuration 13

5. Loiter time 60 mins

6. Operational limit Sea State 04

7. Endurance 180 mins

8. Service Ceiling FL 100

9. Atmosphere Indian Reference Atmosphere

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3.1 Airport ICAO CODE : VAJJ Table 2. Airport ICAO CODE

Airport type CIVIL

Temperature (F) 86

Wind speed 6

Runway distance 1,143m

From this we estimate the max landing and takeoff distances.

3.2 Design Code : FAR 23 COMMUTER From this we can limit the design to certain parameters for aerodynamics, propulsion, structure and stability & control. Such as Engine : TURBOPROP

3.3 Payload weight : 1225kgs This is max. Payload weight estimated from Requirements which is about 1225 kgs ( see Table 1). So from we can estimate the max. take-off weight of aircraft.

3.4 Seat Configuration : 13 This is max seat configuration estimated from Requirements which is about 13 ( see Table 1). so from this we can estimate the cabin size .

3.5 Loiter time : 60 mins This is Loiter time given in Requirements ( see Table 1) , so from this we can estimate the fuel capacity.

3.6 Operational Limit : Sea State 04 The WMO sea state code largely adopts the 'wind sea' definition of the Douglas Sea Scale. The following is table representing it : ( see Table 3) . So, sea state 04, wave height = 0.5- 1.25 m from this we can estimate the hull design.

Table 3. Douglas Sea Scale

3.7 Endurance: 180 mins This is max endurance given in Requirements (see Table 1) , so from this we can estimate the fuel consumption.

3.8 Service Ceiling: FL100 The height at which a particular type of aircraft can sustain a max rate of climb. FL= Flight Level

1FL = 100 ft So, FL100 = 10,000ft From , this we must estimate the max rate of climb.

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3.9 Atmosphere: Indian Reference Atmosphere For the purpose of aircraft performance the average Indian reference atmosphere is taken as: 1. Ref temp for take-off and landing: ISA+20 2. Sea level mean temp: ISA+15 3. Upper air operating temp: ISA+15 4. Lapse rate: 6.50C/Km from SL to 16 Km 5. Temp at 16 Km: -740C 6. Lapse rate from 16 Km to 20 Km: - 2.50C/Km 7. Mean sea level pressure: 1005 hPa

4. MISSION PROFILES There two missions considered for design i.e.; pax mission and asr mission profiles are shown in below figures. (see fig 5 and fig 6 respectively).

Fig 5: Passen ger mission (Pax) Mission Profile Fig 6: Air-Sea Rescue (ASR) Mission Profile

5. INFORMATION RETRIEVAL Here, the surveys of various existing amphibian aircrafts are considered to have working out statistics in order to bring trend functions to plot various graphs to get various parameters. Following the tables made of some amphibian aircrafts that meet the given missions. Table 4 : Comparison of Various Amphibian aircrafts Aircraft specifications Beriev Be-12 Beriev Be-200 Altair PBY-5A Seastar CD-2 JRF-5 Goose Crew 2 2 10 1 3 Passengers Capacity 0 44 0 12 7 Wingspan 29.84 m (97 ft 11 in) 32.8 m (107 ft 7 in) 31.70 mt (104 ft 0 in) 17.74 m (58 ft 2 in) 14.94 m (49 ft 0 in) Wing area 99.0 sq m 117.4 sq m 130 sq m 30.6 sq m 34.9 sq m Empty weight 24,000 kg (52,800 lb) 27,600 kg (60,850 lb) 9,485 kg (20,910 lb) 2,900 kg (6,393 lb) 2,466 kg (5,425 lb) Max. takeoff weight 36,000 kg (79,200 lb) 41,000kg (90,390 lb) 16,066 kg (35,420 lb) 4,600 kg (10,141 lb) 3,636 kg (8,000 lb) Powerplant Selected 2 Turbo Props 2 Turbo Fans 2 Piston Engines 2 Turbo Props 2 Piston Engines Maximum speed 530 km/h (330 mph) 700 km/h (435 mph) 314km/h (196 mph) 335 km/h (208mph) 324 km/h (301 mph) Range 3300 km (1800 nmi) 2100 km (1134 nmi) 4030 km (2176 nmi) 1741 km (940 nmi) 1,030 km (557 nmi) Service ceiling 8000 m (26,247 ft) 8,000 ft (26,246 ft) 4000 m(15,800 ft) 4500 m (14,800 ft) 6,494 m (21,300 ft) Wing loading 298 kg/sq m 235 kg/sq m 123.6 kg/sq m 95 kg/sq m 104 kg/sq m Airfoil NACA 23020 TsAGI 16% NACA 21 NACA 23018 NACA 23015 R/C 15.2m/s 17m/s 5.1 m/s 6.6m/s 5.6 m/s Aspect ratio 8.9 9.1 7.73 10.3 6.4 Length 30.11 m (98 ft 9 in) 32 m (105 ft) 19.46 m (63 ft 10 in) 12.70 m (41 ft 8 in) 11.74 m (38 ft 6 in)

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Height 7.94 m (26 ft 1 in) 8.9 m (29 ft 2 in) 6.15 m (21 ft 1 in) 4.83 m (15 ft 10 in) 4.93 m (16 ft 2 in) cruise speed 473 km/h (356 mph) 560 km/ h (348 mph) 201 km/h (125 mph) 333 km/h (207 mph) 308 km/h (191mph) Endurance 3 hours 4 hours 31 hrs 45 min. 9 hours 12 min 6 hours Seaworthiness sea state 02 sea state 02 sea state 03 sea state 03 sea state 03 Purpose Maritime patrol PAX & ASR Maritime patrol & ASR PAX PAX

Table 5 : Comparison of Various Amphibian aircrafts

Aircraft specifications RD-3 Dolphin G-44 HU-16B Shin Meiwa Us-1A Shin Meiwa Us-2 Crew 2 1 6 9 11 Passengers Capacity 6 4 10 20 20 Wingspan 18 m (60 ft) 12.19 m (40 ft 0 in) 29.47 m (96 ft 8 in) 33.15 m (108 ft 9 in) 33.15 m (108 ft 9 in) Wing area 59.2 sq m 22.8 sq m 96.2 sq m 135.8 sq m 135.8 sq m Empty weight 3,068 kg (6,764 lb) 1,470 kg (3,240 lb) 10,401 kg (22,883 lb) 23,300 kg (51,367 lb) 25,630 kg (56,504 lb) Max. takeoff weight 4,415kg (9,734lb) 2,041 kg (4497 lb) 17,045 kg (37,500 lb) 45,000 kg (99,200 lb) 47,700 kg (94,799 lb) Powerplant Selected 2 Piston Engines 2 Piston Engine 2 Piston Engines 4 Turbo Props 4 Turbo Props Maximum speed 240 km/h (149mph) 246km/h (153 mph) 380 km/h (236 mph) 511 km/h (318 mph) 560 km0h (348 mph) Range 1,114 km (601 nmi) 1,481 km (799 nmi) 4,589 km (2,478 nmi) 3,817 km (2,060 nmi) 4,700 km (2538 nmi) Service ceiling 4,600 m (15,100 ft) 4,500 m (14,600 ft) 6,550 m (21,500 ft) 7,195 m (23,600 ft) 7,195 m (23,606 ft) Wing loading 80 kg/sq m 65 kg/sq m 105 kg/sq m 173kg/sq m 190 kg/sq m Airfoil Clark Y (18%) NACA 23015 NACA 23017 NACA 63A221 NACA 63A221 R/C 4.097 m/s 3.6 24 m/s 8.1 m/s 11.8 m/s Aspect ratio 5.47 6.5 9.02 8.09 8.09 Length 13.79 m (45 ft 3 in) 9.47 m (31 ft 1 in) 19.16 m (62 ft 10 in) 33.46 m (109 ft) 33.46 m (109 ft 9 in) Height 4.62 m (15 ft 2 in) 3.48 m (11 ft 5 in) 7.88 m (25 ft 10 in) 9.95 m (32 ft 7 in) 9.8 m (32 ft 2 in) cruise speed 169 km/h (105mph) 222km/h (138mph) 200km/h (124mph) 426 km/h (318mph) 480 km/h (298mph) Endurance 7 hours 7 hours 17.4 hours 26 hours 10 hours Seaworthiness sea state 03 sea state 03 sea state 03 sea state 05 sea state 05 Purpose PAX & ASR PAX ASR ASR ASR

6. CONFIGURATION SELECTION From above Survey we would conclude the configuration that meet or exceeds given requirements in the problem statement. So, the conceptual configurations as follows ( see Table 6.1 ,Table 6.2, Table 6.3 and Table 6.4). Table 6.1: Conceptual Configuration 1

Aircraft Type Flying Boat Wing Configuration Gull wing Wing Position Parasol Wing

Tail Configuration Conventional

Engine Turboprop

Configuration Number of Engines 2

Engine Location Wing (puller)

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Table 6.2 : Conceptual Configuration 2

Aircraft Type Flying Boat

Wing Configuration Gull wing

Wing Position High Wing

Tail Configuration T-Tail

Engine Turboprop

Configuration Number of Engines 2

Engine Location Wing (puller)

Table 6.3 : Conceptual Configuration 3

Aircraft Type Floatplane Wing Configuration Gull wing

Wing Position High Wing

Tail Configuration Conventional Engine Turboprop

Configuration

Number of Engines 2

Engine Location Wing (puller)

Table 6.4 : Conceptual Configuration 4

Aircraft Type Floatplane

Wing Configuration Gull wing

Wing Position Parasol wing

Tail Configuration T-tail Engine Turboprop

Configuration

Number of Engines 2 Engine Location Wing (puller)

By design-down selection, we have as following (see Table 6 ), design-down selection is the conceptual selection where ranking decides the best suitability of concept to problem statement requirements.

0 - If it doesn't meet the requirement 1- If it meets the requirement but not much than other concept 2- If it meets the requirement

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Table 6 : Ranking for Configuration Selection

Requirements 1 concept 2 concept 3 concept 4 concept

Airport ICAO CODE 2 2 2 2

DESIGN CODE 2 1 1 0

Payload weight 2 1 1 0

Seat Configuration 2 2 1 1

Loiter time 2 0 0 0

Operational limit 2 1 1 0

Endurance 2 1 1 0

Service Ceiling 2 1 1 1

Atmosphere 2 2 2 2

Ranking 18 11 9 6

So, Conceptual Configuration 1 meets the requirement as per design-down selection method done using ranking of weight age.

7. CONCEPTUAL IDEA AND GENERAL VIEWS

Fig 7 : Conceptual Idea and General Views

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8. WEIGHT ESTIMATIONS

Table 7 : Weight Estimation

ퟐ Aircraft Empty Weight Takeoff Weight 퐗 = 퐥퐨퐠⁡(푾푬) 퐘 = 퐥퐨퐠⁡(푾푶푻) 푿 푿풀

Beriev Be-12 52800 79200 4.7226 4.8987 22.3029 23.1346

Beriev Be-200 Altair 60850 90390 4.7842 4.9561 22.8885 23.7110

PBY-5A 20,910 35,420 4.3203 4.5492 18.6650 19.6539

Seastar CD-2 6,393 10,141 3.8057 4.0060 14.4834 15.2456

JRF-5 Goose 5,425 8,000 3.7343 3.9030 13.9450 14.5750

RD-3 Dolphin 6,764 9,734 3.8302 3.9882 14.6704 15.2756

G-44 3,240 4497 3.5105 3.6529 12.3236 12.8235

HU-16B 22,883 37,500 4.3595 4.5740 19.0052 19.9403

Shin Meiwa Us-1 51,367 99,200 4.7106 4.9965 22.1898 23.5365

Shin Meiwa Us-2 56,504 94,799 4.7520 4.9767 22.5815 23.6493

TOTAL 42.5299 44.5013 183.0553 191.5453

Fig 8 : Iterations for Take off weight

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Calculated values ; Take-off weight = 17810 lb Empty weight = 11559 lb Fuel weight = 3561.36 lb Where meets the design code of FAR 23 where in the commuter category , the max. take-off weight is limited to 19,000 lb.

9. INITIAL SIZING The concept of “Similar airplanes” as introduced here is generally valid for the subsonic airplanes. i. From the data collection on similar airplanes, the wing loading (W/S) is chosen as 100kg/sq.m. Then, S = W / (W /S) ie W/S=100kg/sq.m. So, S= 80.78 sq.m ii. From data collection on similar airplanes the aspect ratio (A) of the wing is chosen, ie A =10.Consequently, the wing span (b) is given by: b = (S × A)1/2, then b=28.42m iii. Wing taper ratio is the ratio between the tip chord and the centerline root chord which is chosen as 0.4 based on the most wings of low sweep have a taper ratio of about 0.4-0.5.So, Root Chord length = 4.06 m and Tip Chord length = 1.62 m.

iv. We have equation from data collected lo g(퐿) = −8.8403 + ⁡2.2632log⁡(푊푂푇 , At 푊푂푇 = 17810⁡lb. Therefore, L=12.023m v. Similar procedure is validated for calculating Ground to the Top of the Wing , H=4.83 m vi. From the data collection on similar airplanes, we obtain angle of incidence as 6 degrees. vii. Flap Area , 푆푓=0.2 × S = 0.2 × 80.78 = 16.16 sq.m viii. Wing Sweep, At this stage an unswept wing is chosen, ᴧ=0. ix. Wing location, the high wing location is chosen such airplanes. x. Cabin size , for such 13 seater airplane the cabin size can be noticed as width= 4.2 m , height = 2.8 m xi. So, the fuselage maximum outer dimensions can be chosen as height = 4.8 m , width = 4.4 m. xii. From the data collection we chosen 푆ℎ푡/푆=0.25 and 푆푒/푆ℎ푡=0.30 , based on above figure we chosen Aspect Ratio= 6 and Taper ratio = 0.3. So , HT area = 20.20sq.m , Elevator area = 6.06 sq.m. H. Tail Span , 푏ℎ푡= 11m. H. Tail Root Chord, 퐶푟ℎ푡 =2.8m and H.Tail Tip Chord , 푐푡ℎ푡= 0.8 m xiii. From the data collection we chosen 푆푣푡/푆=0.20 and 푆푟/푆푣푡=0.35 , based on above figure we chosen Aspect Ratio= 1.5 and Taper ratio = 0.4. So , VT area = 16.16 sq.m , Rudder area = 5.66sq.m. V. Tail Span , 푏푣푡= 4.4m V. Tail Root Chord, 퐶푟푣푡 =2.2m and V.Tail Tip Chord , 푐푡푣푡=1.8m 10. ALTERNATIVE MISSIONS AND APPLICATIONS Other missions which can be applicable by this Amphibian aircraft , where it had more advantage than a ship, Conventional Fixed Wing and Helicopter. Here, the comparative study of these vehicles with Amphibian aircraft shown below.

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11. CONCLUSION Conceptually designed aircraft was successfully meet all the design requirements taken by the problem statement . It was picked out of four different configurations that represent current industry of amphibious transport aircraft. The aircraft is capable to complete all required missions specified by problem statement and capable of having two configurations: passenger version and a ASR variant. The aircraft designed would be capable of operating out of Juhu Airport (ICAO Code: VAJJ) in Mumbai. The Pax mission would be involved two daily return flights to Pavana Lake (Ref. Fig 2.1.a) & the ASR mission would be involved a three hour search over the off-shore rigs located in the DCS Block and Panna-Bassein Blocks of Bombay High Oilfield which is met by the currently designed multipurpose amphibian aircraft.

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