Sport Aviation of the Future. Possible Concepts for Future Sport Aircraft Using Different Environmental Friendly Propulsion Concepts Patrick Berry Fluid and Mechatronic Systems

Introduction  A new generation of sport aircraft will require radical changes to the propulsion system  Why?  In the future fossile fuel will be scarce or at least limited and too expensive  Fossile fuel is bad for the environment and might also be prohibited to use in the future because of its environmental impact  So what are the options?!  1) Use bio fuels  2) Go electric ICAS 2010

Introduction  This study will focus on electric propulsion and what this means for the design and use of such aircraft  Different power sources like the sun, batteries and fuel cells will be covered ICAS 2010

Solar powered aircraft  Sources of inspiration:  Human powered aircraft ICAS 2010 Gossamer Albatross Daedalus (MIT)

Solar powered aircraft  Sources of inspiration:  Solar powered aircraft ICAS 2010 Powered configuration Configured as a glider Solair 2

Questions  Is it possible to design something like this which is commercially viable?  …. and to which category do we certify it?  Is there a market?  Will the market accept it? ICAS 2010

Solar powered aircraft  The Sun peaks at 1000 W/m2 (in summertime, at noon on a clear day)  An average of 800 W/m2 can be expected (in southern Europe)  This indicates flight times around 7 hrs on pure solar power  But the aircraft won´t be able to take-off and climb on solar power, so it needs to be a hybrid using batteries to assist  Batteries are an additional dead weight which needs to be minimised, so we are looking for a battery with high energy density (Wh/kg) ICAS 2010

Battery trends in energy density

Quinetic Zephyr using Li-S (350 Wh/kg) Endurance: 2 weeks ICAS 2010

Solar powered aircraft  Affordable solar cells are in the range of 15-20% in efficiency. We need to work with the most efficient ones in order to reduce size, weight and stay reasonable in cost  Essential to minimise losses in the overall power chain ICAS 2010

Solar powered aircraft  How would you use such a plane?  Due to its low power-to-weight ratio it´s more suitable as a powered glider, i.e. a glider with self launch capability ICAS 2010

Specification for a solar powered aircraft  Average solar radiation = 800 W/m2  Max. sink rate in glider configuration: less than 0.7 m/s  Cruise speed in solar powered mode: 20% higher than stall speed  The aircraft shall be a hybrid, i.e. battery power for take-off and climb, solar power for cruise  Min. climb speed: 2m/s  Single seater or two seater  Pilot or passenger weight: 90 kg (+7 kg for parachute)  Certification: CS 22, motorgliders ICAS 2010

Typical sizing diagram for solar powered flight ICAS 2010

Solar powered aircraft  Two configurations are presented: 1.Conventional layout 2.Canard configuration ICAS 2010

Linköpings universitet Sid 17 ConventionalSingle-seaterTwo seater Overall length (m) Span (m) A23 S (m2) Empty weight (kg) Battery weight (kg)36 (Li-ion) 25 (Li-S)66 (Li-ion) 42 (Li-S) Pilot+parachute (kg) MTOW (kg) Max shaft power (kW) (T-off, climb) 816 Solar shaft power (kW) (cruise) Propeller dia. (m)22 Cruise speed (km/h) (L/D)max33 Endurance (h)6.9 Climb rate (m/s) ICAS 2010

CanardSingle-seaterTwo seater Overall length (m)7.48 Span (m) A18 S (m2) Empty weight (kg) Battery weight (kg)36 (Li-ion) 24 (Li-S)66 (Li-ion) 39 (Li-S) Pilot+parachute (kg) MTOW (kg) Max shaft power (kW) (T-off, climb) 816 Solar shaft power (kW) (Cruise) Propeller dia. (m)22 Cruise speed (km/h)8076 (L/D)max3335 Endurance (h)6.9 Climb rate (m/s) ICAS 2010

Typical V-n diagram for a solar powered aircraft ICAS 2010

Problem areas  Requires skilled pilot due to lack of excess power  Solar cell integration on wing and stabilizer  Solar cell integration requires stiff surfaces (brittle cells)  Solar cells need to be embedded for low drag (without too much energy losses)  Aircraft limited in use as to where and when you can operate it  Big question= Maintenance of solar cells!! ICAS 2010

Problem areas ICAS 2010

Battery powered aircraft  Source of inspiration: PC Aero Electra One ICAS 2010

Battery powered aircraft  Battery powered aircraft are based on the sun powered configurations shown previously  Main difference: Wing loading can be increased since sun power is eliminated (saves weight)  Since battery weight will be even more dominant in this case, we need to decrease structure weight as much as possible (wing essentially)  No sun power means no need for non-tapered wings any more, i.e. weight potential  Aspect ratio can be reduced (weight saver), which means somewhat reduced soaring performance, ICAS 2010

Specification for a battery powered aircraft  Maximize range/endurance  Min. cruise speed : 20% higher than stall speed  Min. climb speed: 2m/s  Single seater or two seater  Pilot or passenger weight: 90 kg (+7 kg for parachute)  Certification: CS 22, motorgliders Linköpings universitet Sid 26 ICAS 2010

ConventionalSingle-seaterTwo seater Overall length (m)7.68 Span (m) A15 S (m2) Empty weight (kg) Battery weight (kg)76 (Li-ion) 76 (Li-S)155 (Li-ion) 155 (Li-S) Pilot+parachute (kg) MTOW (kg) Max shaft power (kW)1225 Propeller dia. (m)22 Min. cruise speed (km/h)84 (L/D)max2627 Endurance (h) Climb rate (m/s)21.8 Max cruise speed (km/h) Linköpings universitet Sid 29 ICAS 2010

CanardSingle-seaterTwo seater Overall length (m)7.68 Span (m) A13 S (m2)917.7 Empty weight (kg)97183 Battery weight (kg)76 (Li-ion) 76(Li-S)155 (Li-ion) 155 (Li-S) Pilot+parachute (kg) MTOW (kg) Max shaft power (kW)1225 Propeller dia. (m)22 Min. cruise speed (km/h)92 (L/D)max2830 Endurance (h) Climb rate (m/s) Max cruise speed (km/h) Linköpings universitet Sid 30 ICAS 2010

Pros and cons  Battery powered aircraft are probably the easiest way to replace current combustion engine types (except for bio fuels)  Battery powered aircraft have power to spare, thus easier to fly, require ”normal skilled pilots”  Might be more interesting for the market since range of speed is greater  Big pro = existing infrastructure!  Limited use in terms of over the year useage  Batteries don´t work that good in a cold environment ICAS 2010

Fuel cell powered aircraft  Source of inspiration: Linköpings universitet Sid 32 DLR Antares ICAS 2010

Fuel cell powered aircraft compared to battery powered ICAS 2010

Fuel cell powered aircraft  The DLR Antares is a derivative of an existing aircraft. It carries two external wing pods. One is the hydrogen tank the other is the fuel cell  In a blank paper design you would probably try to integrate the tank and fuel cell more  One big problem is to house the large pressurised tank (45 MPa), needs to be placed close to the C of G  Suggestion: place it in the main spar! ICAS 2010

Fuel cell powered aircraft  The fuel cell powered aircraft concepts are based on the battery powered concepts previously shown  Same specification  Battery weight exchanged for fuel cell + tank weight  Only differrence is in endurance ICAS 2010

ConventionalSingle-seaterTwo seater Overall length (m)7.68 Span (m) A15 S (m2) Empty weight (kg) Battery weight (kg)76 (Li-ion) (Fuel cell)155 (Li-ion) (Fuel cell) Pilot+parachute (kg) MTOW (kg) Max shaft power (kW)1225 Propeller dia. (m)22 Min. cruise speed (km/h)84 (L/D)max2627 Endurance (h) Climb rate (m/s)21.8 Max. cruise speed (km/h) Linköpings universitet Sid 36 ICAS 2010

CanardSingle-seaterTwo seater Overall length (m)7.68 Span (m) A13 S (m2)917.7 Empty weight (kg)97183 Battery weight (kg)76 (Li-ion) (Fuel cell)155 (Li-ion) (Fuel cell) Pilot+parachute (kg) MTOW (kg) Max shaft power (kW)1225 Propeller dia. (m)22 Min. cruise speed (km/h)92 (L/D)max2830 Endurance (h) Climb rate (m/s) Max. cruise speed (km/h) Linköpings universitet Sid 37 ICAS 2010

Pros and cons  Technology seems promising  Still in early development stage, not mature  Lack of infrastructure!!  Use is limited by the same reason as battery powered aircraft:  Gas performance degrade with lower temperature ICAS 2010

How we prepared the study  We used an in-house design program, which we rearranged  The rearrangement included:  Adding solar power model  Adding electric motor model  Adding battery model  Adding fuel cell model  Rearranged weight equations in weight module  The electric motor model and weight equations were trimmed against published Solair 2 data  We benchmarked against existing aircraft in the category and found good relevence Linköpings universitet Sid 39 ICAS 2010

Conclusions  This study has shown that it´s quite possible to design electric aircraft with different power sources, even using today´s technology  The ability to design light and with low drag is emphazised more than ever  ”Green aircraft” won´t be any high speed machines  Live ”green”= eat ”slow food”  Fly ”green”= fly slowly  Will the market accept slow flight?  Personal view: the market might digest battery powered aircraft in the very near future, but the other variants will probably have to wait for a while ICAS 2010

Questions? ICAS 2010