UAV and the environment

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Environmental impact

PredatorB_1.jpg

Environmental impact

There is a rapidly growing awareness of the need for all of us to be more conscious of the environmental impact of our activities and to reduce our use of fossil fuels.

From The Financial Times, 12 July, 2005. From The Financial Times, 12 July 2005.

A responsible environmental approach is also a good business approach, echoing the maxim “waste not, want not” and supporting the GE drive to be more environmentally conscious.

From The Financial Times, 28 September, 2005. From The Financial Times, 28 July 2005.

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Relative environmental impact of a manned aircraft and an Unmanned Air Vehicle

Raw materials usage on building and materials disposal on decommissioning:

a manned Cessna Skylane requires at least 860 Kg of raw materials to build
a UAV with a 10 Kg payload only requires 34 kg of raw materials to build

From the “Metro”, 21 September, 2005

For every kilogram of AVGAS aviation fuel used, an aircraft engine produces:

2.891 Kg of CO₂ +
1.124 Kg of H₂O +
0.019 Kg of NO_x

Fuel usage for every 100 Km flown:

a manned Cessna Skylane will use 15.20 Kg of AVGAS
a UAV with a 10 Kg payload will use 1.65 Kg of AVGAS

For a geophysical survey of a 100 Km by 100 Km region, at a line spacing of 100 m:

a manned Cessna Skylane will create 43,942 Kg of CO₂
a UAV with a 10 Kg payload will create 4,770 Kg of CO₂

NOISE LEVELS	manned Cessna 402 – REF 52	calculated for small UAV
cruising at 1,000 feet	72.2 dB	62.6 dB
climbing at 1,000 feet	76.5 dB	66.9 dB
Background noise level = 42 … 52 dB: primarily waves on the beach near the test area. Anything above 85 dB is considered harmful. Noise power is doubled for each extra 3 dB.

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Fuel usage comparison

Maynard Hill’s TAM5 UAV. From http://tam.plannet21.com/ “sm cutout TAM5.jpg.

Cessna Skylane manned light plane. From www.cessna.com.

	parameter	Small UAV Typical specifications $ 35,000	Manned aircraft Cessna Skylane $ 268,750
weight	Dry (no PL, in Kg)	~34	860
	Max fuelled (Kg)	~81	1,406
	Max payload (Kg)	10	91=load + 182=pilot
operational	Fuel type	methanol / Avgas100	Avgas 100 or 100LL
	Fuel capacity Kg,L	40 Kg / 49 L	273 Kg / 333 L
	Max range (Km)	2,400	1,793
	Max flight time (Hr)	30 at 80 Kph	11.8 at 152 Kph
	Fuel used: g / Km	16.5	152
	CO₂ gen in L / Km	35	463
	Max speed Kph	145	276
	Stall speed Kph	50	91
	Impact of accident: KE = 0.5mv²	KE = 0.5x91x50x50 = 114 KJ	KE= 0.5x1243x91x91 = 5,145 KJ

Note that the UAV could fly on either methanol of ethanol. Ethanol can be produced from sugar cane. However, the main problem with both methanol and ethanol, is that the energy density of both is about 70% that of Avgas 100.
The density of Avgas 100 LL, is taken to be that of petroleum = 0.82 Kg / litre.
In the event of an impending crash, planes dump fuel to try to avoid a fire after the crash: the less fuel carried, the less the environmental impact of a fuel dump.

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