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BRF Project: Design a UAV/Drone

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ramana
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BRF Project: Design a UAV/Drone

Postby ramana » 03 Sep 2017 04:32

I would like to start a BRF project for the conceptual design of a UAV of the Predator class.
The study should include concepts, sizing and finally drawing sketches.
The hardware should be all available in India. No imports.
And not trolling. If you want you can remark in Off Topic thread in GDF.

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Re: BRF Project: Design a UAV/Drone

Postby RCase » 03 Sep 2017 04:53

ramana wrote:I would like to start a BRF project for the conceptual design of a UAV of the Predator class.
The study should include concepts, sizing and finally drawing sketches.
The hardware should be all available in India. No imports.
And not trolling. If you want you can remark in Off Topic thread in GDF.

Why the restriction on 'No imports'? I can understand no CKD kits. However, in this day and age it is about design and development leveraging existing sub-systems, using off-the shelf systems. Even in programming, there is tons of code that can be assembled together to build an application really quickly.

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Re: BRF Project: Design a UAV/Drone

Postby ramana » 03 Sep 2017 04:57

If you import why not import while thing and do scredrivergiri.
How do you learn?

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 03 Sep 2017 09:44

I cannot do all that. But my suggestion is to mount Garrett HAL turborpop engines 500-750hp on Rustom -2. Rustom is already big enough for such modications and engines are lighter than Piston engines. Accept loiter time reduction from 36 hours to 12 hours, till the fuel capacity can be increased by drop tanks.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 05 Sep 2017 10:48

Gyan,

1. What is the typical TWR for a MALE recce UAV? With 2700 kgs of AUW, what should be Rustom's thrust requirement?
2. What are you designing your UAV for: fast to altitude and position, but smaller loiter time. Or, slow to climb and reach area of interest, but with longer loiter time? YOU CAN'T HAVE BOTH. For the first, go with a turboprop. For the second, go with the diesels like what ADE is doing.

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Re: BRF Project: Design a UAV/Drone

Postby JayS » 05 Sep 2017 11:11

Gyan wrote:I cannot do all that. But my suggestion is to mount Garrett HAL turborpop engines 500-750hp on Rustom -2. Rustom is already big enough for such modications and engines are lighter than Piston engines. Accept loiter time reduction from 36 hours to 12 hours, till the fuel capacity can be increased by drop tanks.


Very rough calculations - for say a 3000kg MALE with say 20 L/D ratio - for lift of 3000kgf drag should be 150kgf so engine should be of thrust 150kgf i.e. 1.5kN. If the aircraft is to fly at say 120m/s in cruise that gives power of ~240 hp. Add some margin.

500-750hp is too high value.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 05 Sep 2017 11:25

Jay, please check your PM

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Re: BRF Project: Design a UAV/Drone

Postby JayS » 05 Sep 2017 14:08

Indranil wrote:Jay, please check your PM

You missed this I suppose..?

viewtopic.php?f=24&t=6643&start=760#p2207534

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 06 Sep 2017 00:03

Critical to all aeronautical application is the Engine and more importantly the BFSC (Brake Fuel Consumption)
https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

The predator MQ-1 and IAI Heron and NAL Hansa use a ~73KW ROTAX 914 engine (Horizontally opposed 1200cc displacement) that weighs 78Kg (with electric starter, carburetors, fuel pump, air filters and oil system) and consumes ~18.3 L/Hr @73 KW of Unleaded Gasoline 91 Octane or shows a BFSC of 0.203Kg/KW/Hr . The thrust to weight ratio of that Rotax engine is (said to be) significantly superior to all competing engines in that range, infact the ROTAX sells more engines in that range than all the competition combined.
https://en.wikipedia.org/wiki/Rotax_914

Thinking out the box to get a advantage over the ROTAX I scoped out the 1.3L DDIS Fiat Diesel engine which is 70 KW engine (half the cars in India use this engine and is an engine known for its efficiency on road) also for comparison which has similar characteristics as the ROTAX since I assumed that the fuel efficiency of diesels are superior The FIAT 1.3L DDIS weighs 148Kg and consumes 14Kg/Hr of Diesel at Mean Sea Level from my calculations using BFSC numbers of 0.23kg/KW/Hr. So the brilliant plan to use a diesel engine was a flop even before I started unless of course someone tells us that sea level rated diesels will perform better at +8000m where the MALE will operate. It appears from the BFSC data that diesel have much higher weights nearly 2 times greater than comparable Petrol engines with the same Power output and worse the BFSC numbers are not that much superior either in fact appear to be mostly worse unless ofcourse you are looking at some very large maritime engines.

So researching on petrol engines equivalent to the ROTAX using an automobile gasoline engine so I looked at the Swift Petrol engine which is the M13A which displaces 1.3 L (1,328 cc) VVT which develops 68KW and weighs perhaps 70 Kg but don't have the BFSC data or maps yet... but I think that hte M13A may be a good fit. however M13A is not flight rated as yet. Someone else can dig out the exact Weight and BFSC data.

So as far as I am concerned there is very little option but to use ROTAX 914 or the new ROTAX 915 engine (Its a multijet fuel injected with FADEC) or equivalent "indigenous" gasoline engine similar to M13A or the Tata Revotron 1.2L and flight rate it.
Last edited by tandav on 06 Sep 2017 11:02, edited 2 times in total.

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 06 Sep 2017 00:40

I know 500hp-750hp is way excessive. I read the specifications of Reaper on wiki but the problem is that we don't have indigenous 200hp - 300hp diesels. Automotive diesels are heavy and turning them into aeronautical diesels is non trivial task. The weight of Ruston-2 has shot up by more than Twice therefore we need diesels of 230hp each and after making allowances for deraiting of diesels at high altitude around 275-300hp. Even then UAV will have poor performance at high altitude above 18000feet while we need 41000 feet. Also slower UAV will be easier to kill. Hence, I am sacrificing loiter time to allow the UAV To take off with payload and weapons, fly higher and faster, which it cannot do presently.

Hence:-
Empty weight 2100kg-2500kg
Fuel 1500 kg for half the loiter time
Sensor payload 500kg-800kg
Weapons 250kg-500kg or drop tanks of same weight

MTOW 4200-5000kg

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 06 Sep 2017 00:54

Indranil wrote:Gyan,

1. What is the typical TWR for a MALE recce UAV? With 2700 kgs of AUW, what should be Rustom's thrust requirement?
2. What are you designing your UAV for: fast to altitude and position, but smaller loiter time. Or, slow to climb and reach area of interest, but with longer loiter time? YOU CAN'T HAVE BOTH. For the first, go with a turboprop. For the second, go with the diesels like what ADE is doing.


ADE Is unable to get their UAV/Rustom-2 to take off with reasonable fuel or with any Sensors. They have been lying for 5 years about non existent problem of actuators. Their empty weight is more than envisaged AUW. Hence to cut the loop of slow iterative improvements, go turboprop. Turborpop engines will be lighter and will not add to weight inspite of being 2-4 times more powerful than pistons. We have fully ready UAV, screw in indigenous turboprop engines, and the bloody thing will atleast fly with sensors and payload. What's the point of loiter time with zero fuel and zero sensors?

AUW of 2700kg is only targeted, not achieved and AUW 2700kg also presumes that weapon load is zero and their will be no weight increase/overshoot in sensors or fuel. I think AUW of 2700kg is still over optimistic and it would be quicker to target 5000kg as Rustom-2 already has the size/wing. Hansa & Saras also failed due to failure to do "deep" corrective surgery or reboot.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 01:15

I don't think your information is correct. Rustom-2 was planned to weigh in around 1800 kg. Currently, its AUW is about 2700 kgs. They already had the roadmap to decrease the weight by 240 kgs. Having heavier but more powerful diesel engines, and more fuel is going to push the AUW to 2700 which is a very realistic target. Hence, I was very happy to read the weight target.

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Re: BRF Project: Design a UAV/Drone

Postby ramana » 06 Sep 2017 02:04

Indranil, Are there flight certified diesel engines which give the required power?

What exactly are the Rustom-2 parameters:
Weight, wing span, aerofoil.

Here are Heron parameters:

General characteristics
Crew: two on ground
Length: 8.5 m (27 ft 10 in)
Wingspan: 16.60 m (54 ft 5 in)
Height: ()
Max. takeoff weight: 1,150 kg (2,530 lb)
Powerplant: 1 × Rotax 914, 86 kW (115 hp)

Performance
Maximum speed: 207 km/h (113 knots, 130 mph)
Range: 350 km (189 nm, 217 mi)
Service ceiling: 10,000 m (32,800 ft)
Rate of climb: 150 m/min (492 ft/min)
Wing loading: 89 kg/m² (18.2 lb/ft²)

Endurance: 52 hours[32]
Payload: 250 kg (550 lb)



Predator

General characteristics
Crew: none on-board
Length: 27 ft (8.22 m)
Wingspan: 48.7 ft (14.8 m); MQ-1B Block 10/15: 55.25 ft (16.84 m))
Height: 6.9 ft (2.1 m)
Wing area: 123.3 sq ft[118] (11.5 m2)
Aspect ratio: 19.0
Empty weight: 1,130 lb[117] (512 kg)
Loaded weight: 2,250 lb (1,020 kg)
Max. takeoff weight: 2,250 lb[117] (1,020 kg)
Powerplant: 1 × Rotax 914F turbocharged four-cylinder engine, 115 hp[117] (86 kW) (4.8 kW redundant/6.4hp)

Performance
Maximum speed: 135 mph (117 knots, 217 km/h)
Cruise speed: 81–103 mph (70–90 knots, 130–165 km/h)
Stall speed: 62 mph (54 knots, 100 km/h) dependent on aircraft weight
Range: 675 nmi (675 mi or 1,100 km) [119]
Endurance: 24 hours[1]
Service ceiling: 25,000 ft[117] (7,620 m)

Armament

Hardpoints: 2 and provisions to carry combinations of: Missiles: * 2 × AGM-114 Hellfire (MQ-1B)
4 × AIM-92 Stinger (MQ-1B)
6 × AGM-176 Griffin air-to-surface missiles[120]


Avionics

ASIP-1C
AN/AAS-52 Multi-Spectral Targeting System
AN/ZPQ-1 Synthetic Aperture Radar (early airframes only)

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 02:08

tandav wrote:Critical to all aeronautical application is the Engine and more importantly the BFSC (Brake Fuel Consumption)
https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

The predator MQ-1 and IAI Heron and NAL Hansa use a ~73KW ROTAX 914 engine (Horizontally opposed 1200cc displacement) that weighs 78Kg (with electric starter, carburetors, fuel pump, air filters and oil system) and consumes ~18.3 L/Hr @73 KW of Unleaded Gasoline 91 Octane or shows a BFSC of 0.203g/KW/Hr . The thrust to weight ratio of that Rotax engine is (said to be) significantly superior to all competing engines in that range, infact the ROTAX sells more engines in that range than all the competition combined.
https://en.wikipedia.org/wiki/Rotax_914

Thinking out the box to get a advantage over the ROTAX I scoped out the 1.3L DDIS Fiat Diesel engine which is 70 KW engine (half the cars in India use this engine and is an engine known for its efficiency on road) also for comparison which has similar characteristics as the ROTAX since I assumed that the fuel efficiency of diesels are superior The FIAT 1.3L DDIS weighs 148Kg and consumes 14Kg/Hr of Diesel at Mean Sea Level from my calculations using BFSC numbers. So the brilliant plan to use a diesel engine was a flop even before I started unless of course someone tells us that sea level rated diesels will perform better at +8000m where the MALE will operate. It appears from the BFSC data that diesel have much higher weights nearly 2 times greater than comparable Petrol engines with the same Power output and worse the BFSC numbers are not that much superior either in fact appear to be mostly worse unless ofcourse you are looking at some very large maritime engines.

So researching on petrol engines equivalent to the ROTAX using an automobile gasoline engine so I looked at the Swift Petrol engine which is the M13A which displaces 1.3 L (1,328 cc) VVT which develops 68KW and weighs perhaps 70 Kg but don't have the BFSC data or maps yet... but I think that hte M13A may be a good fit. however M13A is not flight rated as yet. Someone else can dig out the exact Weight and BFSC data.

So as far as I am concerned there is very little option but to use the ROTAX 914 or the new ROTAX 915 engine (Its a multijet fuel injected with FADEC).

Diesels will always be heavier. But the SFC is the lure. Diamond which makes its aircraft with both the gasoline and the diesel engine says that the later is 46% more fuel efficient! Now that number may be inflated. But the increased speed and climb-rate are not. In fact none of the other manufacturers trying the diesel out contradict the fuel efficiency of the diesels.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 02:10

ramana wrote:Indranil, Are there flight certified diesel engines which give the required power?

Yes, multiple of them. I don't know why VRDE is developing one. :D
ramana wrote:What exactly are the Rustom-2 parameters:
Weight, wing span, aerofoil.

Will get you these later.

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 06 Sep 2017 10:05

Indranil wrote:
tandav wrote:Critical to all aeronautical application is the Engine and more importantly the BFSC (Brake Fuel Consumption)
https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

The predator MQ-1 and IAI Heron and NAL Hansa use a ~73KW ROTAX 914 engine (Horizontally opposed 1200cc displacement) that weighs 78Kg (with .... snipped

Diesels will always be heavier. But the SFC is the lure. Diamond which makes its aircraft with both the gasoline and the diesel engine says that the later is 46% more fuel efficient! Now that number may be inflated. But the increased speed and climb-rate are not. In fact none of the other manufacturers trying the diesel out contradict the fuel efficiency of the diesels.


Any data that backs up above statement. The SFC of the best automobile diesel Audi TDI is still 0.200 kg/KW/hr for the 100HP/70 KW engines that are required but the weight is nearly 2 times more. The ROTAX 914 SFC is similar at 0.2 Kg/KW/Hr.

The AE300 diesel engine mentioned is rated at 125 KW peak and 125KW@60%=75KW Continuous. AE300 gives a specific fuel consumption of 19*0.84/(60%*125) = 0.2128kg/KW/Hr at 60% cruise and 0.2352 Kg/KW/Hr at max power, ref below
https://en.wikipedia.org/wiki/Austro_Engine_E4
Displacement : 1990cc
Dry Weight : 186 kg
Power output: 168 hp (125 kW) (maximum takeoff and continuous power) at up to 2,300 RPM
Specific power: 1.38 hp/cu in (62.80 kW/l)
Fuel consumption: 35 l/h (9.25 US gal/h) at 100% power, and 19 l/h (5.02 US gal/h) at 60% power

As I see the Rotax914 beats the AE300 diesel in both SFC and in weight. There is something fundamentally problematic for diesels in aerospace. Also note that a heavier engine means heavier support gear and everything balloons from there. Choosing a diesel as the powerpack dooms your UAV simply because Gasoline has a higher specific 48000 Kj/Kg as compared to diesel which is 44800 KJ/Kg.
http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 06 Sep 2017 11:18

Diesels are not only heavier but they inherently generate more vibrations hence require stronger airframe.

Diesels also have serious derating after 18000feet.

Diesel also turns viscous in cold envoirment of high altitude further decreasing engine efficiency.

That's the reason Predator and Heron went turboprop when AUW crossed seriously above 1000kg.

There is NO aerospace diesel in 200hp category in "extensive use" anywhere in the world.

Why not simply follow tried and trusted path rather than continue minor tinkering with pistons. Diesel theory is sound but is not in General use anywhere in the world.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 12:00

tandav wrote:
Indranil wrote:Diesels will always be heavier. But the SFC is the lure. Diamond which makes its aircraft with both the gasoline and the diesel engine says that the later is 46% more fuel efficient! Now that number may be inflated. But the increased speed and climb-rate are not. In fact none of the other manufacturers trying the diesel out contradict the fuel efficiency of the diesels.


Any data that backs up above statement. The SFC of the best automobile diesel Audi TDI is still 0.200 kg/KW/hr for the 100HP/70 KW engines that are required but the weight is nearly 2 times more. The ROTAX 914 SFC is similar at 0.2 Kg/KW/Hr.

The AE300 diesel engine mentioned is rated at 125 KW peak and 125KW@60%=75KW Continuous. AE300 gives a specific fuel consumption of 19*0.84/(60%*125) = 0.2128kg/KW/Hr at 60% cruise and 0.2352 Kg/KW/Hr at max power, ref below
https://en.wikipedia.org/wiki/Austro_Engine_E4
Displacement : 1990cc
Dry Weight : 186 kg
Power output: 168 hp (125 kW) (maximum takeoff and continuous power) at up to 2,300 RPM
Specific power: 1.38 hp/cu in (62.80 kW/l)
Fuel consumption: 35 l/h (9.25 US gal/h) at 100% power, and 19 l/h (5.02 US gal/h) at 60% power

As I see the Rotax914 beats the AE300 diesel in both SFC and in weight. There is something fundamentally problematic for diesels in aerospace. Also note that a heavier engine means heavier support gear and everything balloons from there. Choosing a diesel as the powerpack dooms your UAV simply because Gasoline has a higher specific 48000 Kj/Kg as compared to diesel which is 44800 KJ/Kg.
http://www.engineeringtoolbox.com/fuels-higher-calorific-values-d_169.html

You have to check your numbers boss.

Diamond doesn't agree with you for the DA-42 NGs,
Diamond claims the Austro is a hefty 46 per cent less thirsty than its gasoline rivals.


Cessna does not agree with you for its for its 182 Skyhawk
Final performance figures include an improved range of 963 nautical miles, an increase of 78 nautical miles over original estimates and a 50 percent improvement over the gasoline-powered Skyhawk, a takeoff distance of 1,320 feet and a max climb rate of 767 feet per minute. Max speed is 134 knots.


EPS doesn't agree with you for its modified Cirrus SR-22
The Graflight V-8 diesel claims the highest fuel efficiency of any general aviation powerplant, 15 percent more fuel-efficient than any other diesel aircraft engine, and nearly 50 percent more efficient than avgas engines with comparable horsepower.


Also, none of these planes required structural modification except for the engine mounts.

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 06 Sep 2017 20:55

Indranil wrote:

You have to check your numbers boss.

Diamond doesn't agree with you for the DA-42 NGs,
Diamond claims the Austro is a hefty 46 per cent less thirsty than its gasoline rivals.


Cessna does not agree with you for its for its 182 Skyhawk
Final performance figures include an improved range of 963 nautical miles, an increase of 78 nautical miles over original estimates and a 50 percent improvement over the gasoline-powered Skyhawk, a takeoff distance of 1,320 feet and a max climb rate of 767 feet per minute. Max speed is 134 knots.


EPS doesn't agree with you for its modified Cirrus SR-22
The Graflight V-8 diesel claims the highest fuel efficiency of any general aviation powerplant, 15 percent more fuel-efficient than any other diesel aircraft engine, and nearly 50 percent more efficient than avgas engines with comparable horsepower.


Also, none of these planes required structural modification except for the engine mounts.


None of the links have any data/numbers on SFC... So no check can be done on the oft believed but yet unproven superior SFC of the diesels.

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 06 Sep 2017 22:38

Also no reference about 200hp+ diesels
No reference to high altitude requirements
No specific statement that no modification was required for using heavier diesels

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 22:48

These are charts for 350 hp class engines.
Image

[url]This is DeltaHawks engine specs (180 hp class)[/url]
Image
Fuel Consumption – 180 hp

Idle: Less than 0.3 gallons per hour
65% Power: 6.2 gallons per hour
75% Power: 8.0 gallons per hour
Initial Testing: 35-40% increased fuel economy when compared to other competing gasoline engines.


The Austro engines are actually more efficient than the Delta Hawk engines. Actually, the AE330s were quick stitch. The AE440s are their first clean sheet designs.
Clean Sky’s goal is to demonstrate reductions of 30% in sfc, 40% in carbon-dioxide and 50% in nitrogen-oxide emissions in the EC120’s turbine engine. A 30% reduction in direct operating cost and a doubling of range with the same fuel are also targets. The AE440 has a weight-to-power ratio of 0.8 kg/kw (1.3 lb./hp) and a fuel consumption of 235 g/kwh (0.386 lb./hp-hr.) at takeoff power. (This is the worst condition for SFC. In the best case, they are gunning for 200 g/kwh (which I take with a grain of salt)).

So, the two SFC leaders (Austro and EPS) are trying to get to the 200 g/kwh from the current 230-250 g/kwh mark.

I noticed that all diesel engine manufacturers plot power against volume rather than power against weight. Helps them by 15% automatically. :wink:

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 22:49

Gyan wrote:Also no reference about 200hp+ diesels
No reference to high altitude requirements
No specific statement that no modification was required for using heavier diesels

A little bit of Google searching before posting wouldn't hurt, would it?

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 06 Sep 2017 23:42

I am not disputing the point of SFC at all. In fact I had posted similar links in the other concurrent thread on UAVs. This thread was about design and I was arguing that go with indigenous turboprops, accept loiter time of 12 hours instead of 48 hours and benefit by more AUW, faster speed, higher altitude rather struggling with imported 200hp diesels.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 06 Sep 2017 23:52

I will correct myself here. I took 0.200 kg/kWH as the SFC of the 914.

By the way, this is the fuel consumption chart from Rotax for the 914. Link

Image

So at 65%, 75% and 100% power the SFCs are 276 g/kWH, 279 g/kWH and 290 g/kWH. So, the current diesels at 235 g/kWH are obviously more fuel efficient.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 07 Sep 2017 00:18

Gyan wrote:I am not disputing the point of SFC at all. In fact I had posted similar links in the other concurrent thread on UAVs. This thread was about design and I was arguing that go with indigenous turboprops, accept loiter time of 12 hours instead of 48 hours and benefit by more AUW, faster speed, higher altitude rather struggling with imported 200hp diesels.

Turboprops don't give you higher loiter time magically.

First, you have to figure out your power requirement. JayS and I tried to tell you that the power requirements of a 2700 kg recce MALE UAV is about 350 to 400 HP for TO and about 250-325 HP for loiter. At that point, the turboprops are not fuel efficient. By the way, the endurance of Rustom II is above 24 hours.

If your power requirements were that of 400 HP and higher, then the turboprops would be more efficient. But for that, you are talking of a 4500-5000 kg UAV like the Predator-B or Eitan.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 07 Sep 2017 04:34



One should realize that these guys are not fools. If it would have been so easy to say that a diesel engine is doomed to fail, or why not a turboprop, then they would have figured it out quite easily.

By the way, Gyan, you might get a turboprop if they go for the single engine twin boom configuration, because they would need a 400 hp engine.

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 07 Sep 2017 10:04

Indranil wrote:I will correct myself here. I took 0.200 kg/kWH as the SFC of the 914.

By the way, this is the fuel consumption chart from Rotax for the 914. Link

Image

So at 65%, 75% and 100% power the SFCs are 276 g/kWH, 279 g/kWH and 290 g/kWH. So, the current diesels at 235 g/kWH are obviously more fuel efficient.


Quite a damning indictment of to my thesis of superior SFC for the Rotax 914 (from the manufacturer no less), I guess open source data such as wikipedia is not as trust worthy. At 18.3 L/Hr the Rotax914 only develops 47.8 KW which gives an SFC of 282g/KWHr as per the manufacturer.
http://www.rotech.ca/rotax-power-torque-fuel

Indranil : The ESA comparison data given below is not certified by a neutral third party like ESA or FAA. Is there a database of certified SFC data of various engines?
http://eps.aero/the-eps-engine/fuel-consumption/

From an ecosystem perspective: India must have the ability to independently conduct SFC tests for engines via our own ESA/FAA equivalent... China is apparently fast becoming/aiming to become the global certification leader and want to surpass ESA/FAA in this regard. Already most of the new certifications are being done by European ESA rather than the US FAA (FAA certification is considered more bureaucratic, inconsistent and expensive and is beholden to vested interests/incumbents).

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 07 Sep 2017 11:30

So we establish that the prime mover will be ~100 KW, 200g/KWHr diesel running on diesel fuel and not jet fuel since the deployment will be with the army for tactical missions over uncontested space?

Transmission : CVT since the loads are light.
Propeller: Variable Pitch Pusher
Single fuselage system
V-Cant inverted tail fins with small wheels at the bottom edge to reduce requirement to haul in the wheels
single retractable nose wheel

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Re: BRF Project: Design a UAV/Drone

Postby Gyan » 07 Sep 2017 12:37

I think that both myself and Indranil are not far away from each other on facts and even in our arguments. I am not denying that diesel engines theoretically have better SFC but I am raising a different argument that we should go for turboprop to cut the Gordian knot of iterative developments and weight increase.

For instance going for turboprop may not be a solution for Nishant (at present) therefore we have developed a better rotary engine, not that any orders are forthcoming from army even then. With Saras, as we were already using Turboprop, therefore the only solution was to go for higher power turboprop with weight saving in airframe. Hence in both these cases, paradigm change solution was not available.

But with Rustom-2, a paradign change solution is avaialbe. Diesels are problematic and wiki gives a nice summary on it at https://en.wikipedia.org/wiki/Aircraft_diesel_engine

I have also posted some links in my other post at viewtopic.php?f=3&t=2906&start=2000#p2206891

But the problem is that we are trying to ‘import” a high quality Titanium manual typewriter while the world has moved on to computers (like Eitan & Reaper turboprop UAVs in same size category). It is all the more stupid as we have indigenous turboprop while the piston engines will have to be imported. There are loiter time benefits but altitude & speed limitations on piston engine powered UAVs.

Now the original targeted figures seemed to be :-

AUW 1800kg
Empty Weight 750kg (with 115hp Avgas engine) (As predator has empty weigh of 500kg, therefore theoretically possible)
Fuel 500kg
Sensor Payload 350kg
Weapons 200kg

What they seem to have got is :-

AUW 2700kg
Empty Weight 1850kg (extraordinary weight overshoot of 200%?? which is practically unheard off)
Fuel 500kg (with 115hp Avgas engine)
Sensor payload 350 kg (theoretical as Sensor payload has still not been mounted and there might be weight increase there also)
Weapons Nil

Therefore the UAV is hardly capable of flying. They can hardly get it up in air for few minutes with minimal fuel. The same thing happened with HANSA.

The future proposal seem to be to use 180hp (preferable 200hp) diesel engine. Now, if we look at powerpack weight (engine, transmission, fuel injection system, cooling, de-icing, shaft, propeller etc) as a whole then thumb rule is that there will be weight increase of 120kgx2=240kg. I am leaving out airframe strengthening and fuel capacity increase required.

AUW 2950kg
Empty weight 2100kg
Fuel 500kg
Sensor payload 350 kg (theoretical as Sensor payload has still not been mounted and there might be weight increase)
Weapons Nil

Now this iteration will allow us to use “imported” engines and our UAV might get off the ground but with serious limitations of

Speed around 250km/hr
Ceiling around 18000 feet thereafter increasing difficulty above that (Remember kargill heights and Tibetan Plateau is at 20,000 feet to 15,000 feet)
Weapan payload Nil
Loiter time 24 hours
Limited electrical supply for electronics/avionics/radar

Now the solution I am submitting is using turboprop engines 500hp-750hp (which is the concept the whole of the world has adopted);-

AUW 4000kg to 6000kg (Airframe is already big enough)
Empty Weight 1850 kg plus additional wing tanks in fuselage & wings, airframe strengthening, plus increased weight of turboprop engine, add 500-700kg, say total 2500kg
Fuel 1500kg
Sensor payload 350-750 kg (provides for Sensor payload weight increase)
Weapons 200-500kg (provides for possible combat UAV configuration)
Wing tanks 200-500kg (to increase range in future)

Our UAV will have ample reserve power for increased AUW, electronics and electrical supply definitely get off the ground but with limitations of loiter time

Speed around 500km/hr instead of 250km/hr (makes it difficult to shoot down)
Ceiling around 35000 feet and upto 50,000-60,000 feet possible (can be used in Himalayas which is our primary are of interest in forseeable future)
Weapon payload available, so are fuel tanks for increased range and loiter time
Better electrical supply for electronics/avionics/radar
Loiter time 12-15 hours initially but as we improve the loiter time will increase.

Now my conspiracy theory:- The GSQRs on the basis of which that Rutom-2 was designed emphasizing loiter time are outdated and difficult to achieve. The UAV if inducted will only be suitable for plains and hilly regions but not mountains. But we are continuing ploughing the same line in order to allow import of Israeli turboprop UAVs. Rather than going for easy fix. Same thing happened with Catapult launched Nishant, which never got serious orders even thought Catapult was already outdated concept and we continue to import Billions of dollars of Searcher Israeli UAVs without catapult launch off course.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 08 Sep 2017 01:57

Actually, I don't agree at all :D .

Recce UAV's primary requirement is endurance. There are two requirements MALE and HALE. HALE should be turbofan powered. A MALE recce UAV should not weight more than 1700-1800 kgs. For that, I need 250 odd HPs. Why would I go for the turboprop in that regime? They are significantly less efficient than reciprocating engines in that regime. My biggest criticism of Rustom 2 is that it weighs 2700 kgs to carry 350 kgs of equipment for 24 hours. Are our subsystems that

UCAV's priority is expediency and payload. That's where I would go for a turboprop. Such a UCAV will have a AUW of near 5 Tons with a payload of 0.5-1 Ton and an endurance of 6-10 hours.

I would never mix them into a one size fits none situation.

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Re: BRF Project: Design a UAV/Drone

Postby ramana » 08 Sep 2017 02:07

Two questions:
What is HALE?
2) Where are Rustom -2 specs?
Why is the AUW 2700 kgs for the R-2?

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 08 Sep 2017 04:07

ramana wrote:Two questions:
What is HALE?
2) Where are Rustom -2 specs?
Why is the AUW 2700 kgs for the R-2?

1. HALE: High Altitude Long Endurance
2. Length :10.1, wingspan 20.6. If you watch the video that I shared, you will realize why Rustom II is overweight. They have built it to a civilian planes safety specifications. Structural limit od 1.5 times. Sink rate of 10 - 15 feet per second. They are revisiting all that. Also our Indian subsystems are much heavier.

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 12 Sep 2017 08:22

Indranil wrote:I will correct myself here. I took 0.200 kg/kWH as the SFC of the 914.

By the way, this is the fuel consumption chart from Rotax for the 914. Link

Image

So at 65%, 75% and 100% power the SFCs are 276 g/kWH, 279 g/kWH and 290 g/kWH. So, the current diesels at 235 g/kWH are obviously more fuel efficient.


Data suggests that the A good 75 KW diesel is about ~140 Kg and has an SFC of 220g/KWH as compared to 75KW Rotax 914 which is about 80Kg and has an SFC of 290g/KWH. So while developing 75 KW gasoline engine consumes 75KWx(290-220)g/Hr more than the diesel = 5.25 Kg/Hr .

The heavier diesel engine and its mounts and struts and anti vibration fairing etc will result in a plane perhaps 80-100Kg heavier than a comparable gasoline powered UAV all other things held equal (payload). Assuming a 90 Kg heavier plane diesel the implies that Fuel weight that can be carried is 90 Kg less which is equivalent to a (90Kg/5.25Kg/Hr)=17 Hr of flight time difference. Which means if the UAV is mission designed to fly for more than 17 Hrs the diesel is preferable and if it is designed to fly less than 17Hrs then gasoline will be preferable.

The MQ-1 Predator has a reported endurance of 40 Hrs max and the Heron around 50 Hrs max. A typical mission would be around ~30 Hrs.

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 12 Sep 2017 22:48

Yes there is a sweet spot for everything. At 50 HP range, a wankel engine is most efficient. There is no one size fits all.

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 14 Sep 2017 16:39

Can we list all the subsystems that needed for the integration?

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 14 Sep 2017 17:09

Something is black in lentils

https://en.wikipedia.org/wiki/General_Atomics_MQ-1C_Gray_Eagle

Says the MQ-1C gray Eagle (upgrade of the MQ-1) MQ-1C uses a 160 HP ~ 120 KW Thielert Centurion Diesel which has Mercedes lineage. Apparently the MQ-1C faces operational issues across all sub systems.

Interestingly Continental Engines and Thielert Centurion has been acquired by China's AVIC subsidiary Tecnify Motors.
https://en.wikipedia.org/wiki/Thielert_Centurion
https://en.wikipedia.org/wiki/Continental_Motors,_Inc.

AVIC manufactures and sells internationally a MALE called Wing Loong potentially powered by the Thielert-Centurion (100 HP turbocharged engine no other details available)
https://en.wikipedia.org/wiki/CAIG_Wing_Loong
http://www.airforce-technology.com/projects/wing-loong-unmanned-aerial-vehicle-uav/

WIng Loong is an interesting UAV with weight of 1000 Kg and Payload of 200 Kg (100 Kg Armament and/or 100 Kg Sensors)

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 14 Sep 2017 17:16

Interestingly the MQ-1C Gray Eagle has a Fuel capacity of 390 + 200 in centerline... given that the fuel consumption is 0.2Kg/KW we are looking at 24 Kg/Hr fuel consumption = 16 Hr @ 390 Kg and 24Hr @ 590 Kg Fuel load... which is far smaller than the reported endurance of 40-50 Hrs.

It implies that either the fuel capacity is larger or the engine is operating at ~40% power during loiter phase... which is efficiency wise a tradeoff...

I suspect the larger engines allows the UAV to takeoff with heavier payload. Any ideas??

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 14 Sep 2017 20:46

Indranil wrote:These are charts for 350 hp class engines.
Image
...snipped

The Austro engines are actually more efficient than the Delta Hawk engines. Actually, the AE330s were quick stitch. The AE440s are their first clean sheet designs.
Clean Sky’s goal is to demonstrate reductions of 30% in sfc, 40% in carbon-dioxide and 50% in nitrogen-oxide emissions in the EC120’s turbine engine. A 30% reduction in direct operating cost and a doubling of range with the same fuel are also targets. The AE440 has a weight-to-power ratio of 0.8 kg/kw (1.3 lb./hp) and a fuel consumption of 235 g/kwh (0.386 lb./hp-hr.) at takeoff power. (This is the worst condition for SFC. In the best case, they are gunning for 200 g/kwh (which I take with a grain of salt)).


So, the two SFC leaders (Austro and EPS) are trying to get to the 200 g/kwh from the current 230-250 g/kwh mark.

I noticed that all diesel engine manufacturers plot power against volume rather than power against weight. Helps them by 15% automatically. :wink:

EPS Graph above suggests that the EPS 350 HP engine is achieving 0.166Kg/KWHr (nearly linear across the power range) : reading off the curve 6.8 gallons/Hr @ 160 BHP ~120KW, 1 US gal = 3.7854 L , JP8 1 L=0.77 Kg SFC then is = (6.8gal/hr*3.7854L/gal*0.77Kg/L)/(160HP*0.746KW/HP)=0.166kg/kwhr

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Re: BRF Project: Design a UAV/Drone

Postby Indranil » 15 Sep 2017 19:45

tandav wrote:Interestingly the MQ-1C Gray Eagle has a Fuel capacity of 390 + 200 in centerline... given that the fuel consumption is 0.2Kg/KW we are looking at 24 Kg/Hr fuel consumption = 16 Hr @ 390 Kg and 24Hr @ 590 Kg Fuel load... which is far smaller than the reported endurance of 40-50 Hrs.

It implies that either the fuel capacity is larger or the engine is operating at ~40% power during loiter phase... which is efficiency wise a tradeoff...

I suspect the larger engines allows the UAV to takeoff with heavier payload. Any ideas??

The cruise power is significantly less than 100% power. Typically about 70% after the initial climb. But it decreases as the aircraft burns fuel and becomes lighter. You can find the L/D ratio of the UAV. At cruise, it will typically be between 25-30 for MALE UAVs. From there, you can calculate the power and fuel requirements.

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Re: BRF Project: Design a UAV/Drone

Postby tandav » 27 Oct 2017 07:36

geeth wrote:^^Link is directing me to your Linkedin A/c


This is the link of interest
http://www.popularmechanics.com/military/aviation/news/a28100/darpa-factory-in-a-can-drones/


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