PEM Fuel Cell for a RC Aircraft

By: Rebekah Achtenberg

Background-The Plane

Sig Kadet RC Aircraft

Replaced the lithium-polymer battery pack with a Proton Exchange Membrane (PEM) fuel cell stack.

Background-The Motor

Motor Data Maximum Power:

1500W Efficient Operating

Current: 30-50A, 65A max 15 second

Propeller Data 14 x 7

Fuel Cell in UAV

In 2006, first fully fuel cell powered UAV

500W of total power

Fuel Cell Stack 30V, 32 cells,

18.9lbs (8.6kg) Wingspan

21.6ft(6.58m) Length

7.8ft(2.38m)

Initial Concerns

Weight distribution Fuel cells weigh more

than a lithium-polymer battery pack

Hydrogen tank and compressors are also required

Area available for fuel cells and hydrogen storage

Materials used have a lower strength than commonly used materials

Polarization Graph

Use maximum power from engine and the maximum current to find an initial voltage needed

Use polarization chart to figure out the area of cell needed and how many cells are needed

Hydrogen Storage Calculation Used an equivalent 2-stroke 5 oz. RC Engine

Nitromethane was fuel, mf =0.17kg Stoichiometric Reaction

a= 0.75, b= 1, c= 1.5, and d= 3.32

HC =-709kJ/mol QHV= 10920kJ/kg, HC (H2)=120.97MJ/kg Energy within gas tank=1.83MJ

Since FC System is 2 times more efficient than a gas engine, only half of the energy needs to be used

Mass H2 =0.91MJ/120.97=0.0075kg

RRpp hnhn RRpp hnhn RRpp hnhn

Hydrogen Storage

Specifications Hydrogen Storage

Capacity: 9g Diameter:6.4cm(2.5

in) Length:18.2cm(7.2i

n) 2.2lbs (1kg) Rated Discharge:

50W

Compressor System

2 Parker BTC miniature diaphragm pumps Run on 6V O.4lbs each

1/4in. Tygon PVC tubing

CL 0.1623 0.3245 0.4604 0.5563 0.6521 0.7479 0.8438 0.9396 1.0354 1.1312 1.2271 1.2783 1.3296 1.3535 1.3863 1.3651

V∞ [mph] V∞ [ft/s] q [lbf/ft2] -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13

0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

5.0000 7.3333 0.0639 0.0828 0.1657 0.2350 0.2839 0.3328 0.3817 0.4306 0.4795 0.5284 0.5773 0.6262 0.6524 0.6785 0.6907 0.7074 0.6966

10.0000 14.6667 0.2557 0.3313 0.6626 0.9401 1.1357 1.3316 1.5273 1.7230 1.9187 2.1144 2.3100 2.5057 2.6105 2.7152 2.7639 2.8308 2.7875

15.0000 22.0000 0.5752 0.7454 1.4909 2.1152 2.5554 2.9955 3.4357 3.8759 4.3161 4.7563 5.1965 5.6367 5.8722 6.1078 6.2173 6.3680 6.2706

20.0000 29.3333 1.0226 1.3252 2.6505 3.7604 4.5430 5.3254 6.1080 6.8906 7.6732 8.4558 9.2383 10.0209 10.4398 10.8586 11.0532 11.3211 11.1480

25.0000 36.6667 1.5979 2.0707 4.1413 5.8756 7.0984 8.3214 9.5443 10.7671 11.9900 13.2128 14.4357 15.6586 16.3130 16.9675 17.2716 17.6902 17.4197

30.0000 44.0000 2.3009 2.9818 5.9635 8.4608 10.2217 11.9824 13.7433 15.5041 17.2650 19.0259 20.7867 22.5476 23.4900 24.4324 24.8703 25.4731 25.0836

35.0000 51.3333 3.1318 4.0585 8.1170 11.5161 13.9129 16.3095 18.7062 21.1030 23.4997 25.8965 28.2932 30.6900 31.9727 33.2554 33.8515 34.6719 34.1418

40.0000 58.6667 4.0906 5.3009 10.6018 15.0415 18.1719 21.3026 24.4332 27.5637 30.6942 33.8247 36.9552 40.0857 41.7611 43.4365 44.2151 45.2867 44.5942

Lift Calculations

Power Calculations

Power [W]

V∞

[mph] V∞ [ft/s] hpr -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13

0.0000 0.0000 0 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

5.0000 7.3333 0.01 31.4201 29.5031 31.4449 35.1733 40.2940 47.6876 57.1077 68.7964 82.8805 98.8494 116.5685 131.2275 147.2337 161.6267 181.0539 196.7015

10.0000 14.6667 0.173 14.0929 13.1946 14.0929 15.8176 18.1863 21.6065 25.9641 31.3711 37.8862 45.2731 53.4697 60.2507 67.6549 74.3129 83.2996 90.5380

15.0000 22.0000 0.2496 31.8240 29.7533 31.8508 35.8782 41.4095 49.3960 59.5716 72.1976 87.4112 104.6606 123.8006 139.6353 156.9250 172.4722 193.4574 210.3598

20.0000 29.3333 0.3189 57.2490 53.3958 57.2989 64.7929 75.0854 89.9466 108.8811 132.3752 160.6845 192.7818 228.3972 257.8619 290.0343 318.9641 358.0130 389.4646

25.0000 36.6667 0.3785 45.3911 42.2272 45.4321 51.5854 60.0367 72.2393 87.7866 107.0777 130.3226 156.6779 185.9218 210.1155 236.5324 260.2869 292.3501 318.1752

30.0000 44.0000 0.4381 130.6514 121.2084 130.7737 149.1391 174.3630 210.7831 257.1860 314.7628 384.1400 462.8007 550.0830 622.2921 701.1368 772.0349 867.7316 944.8100

35.0000 51.3333 0.4901 175.2721 162.1183 175.4425 201.0247 236.1605 286.8922 351.5294 431.7315 528.3710 637.9421 759.5226 860.1068 969.9341 1068.6922 1201.9937 1309.3606

40.0000 58.6667 0.538 233.9930 215.7323 234.2295 269.7442 318.5216 388.9499 478.6827 590.0234 724.1834 876.2957 1045.0802 1184.7163 1337.1844 1474.2856 1659.3417 1808.3940

Results and Suggestions

For a Sig Kadet RC aircraft, using fuel cells alone does not work. Weight of additional fuel cell system is main reason for

failure Using a battery in combination with a fuel cell

Only need battery for takeoff and landing Use a more efficient propeller

The more efficient the propeller, the less work the system needs to do

Redesign of aircraft to be more suited for fuel cell use i.e. The fuel cell UAV was specifically designed for fuel cells

and the design of the fuselage and wings accounted for this

Economic Concerns

Fuel cells are extremely expensive and not as widely available

Hydrogen Storage is also costly Lithium polymer batteries are readily

available and comparatively inexpensive.

Any Questions?