Your SlideShare is downloading. ×
SSA 2012—Electric Gliders
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×

Introducing the official SlideShare app

Stunning, full-screen experience for iPhone and Android

Text the download link to your phone

Standard text messaging rates apply

SSA 2012—Electric Gliders

5,056
views

Published on

Presentation at the 2012 Soaring Society of America convention on electric-powered sailplanes by David Nadler and Robert Mudd

Presentation at the 2012 Soaring Society of America convention on electric-powered sailplanes by David Nadler and Robert Mudd

Published in: Sports, Technology, Business

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
5,056
On Slideshare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
0
Comments
0
Likes
1
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Electric Gliders Dave Nadler “YO Electric” Robert MuddSSA 2012 Convention Slide 1
  • 2. Why Power a Glider ?• The Promise of Freedom ! From Tows, Landouts, Crews…• Motor Penalties: • Weight • Cost and Complexity and Maintenance • Decision Altitudes Higher (stop Soaring to Land): Plan for motor out and not running situation• Compromises for Different Missions• Touring Motorgliders vs. Performance MGs (electrics are not for Touring)SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 2
  • 3. Why Electric ? Gas Problems...• Reliability (* Jonas De Rese PhD thesis at Delft University) • Both for the self-launching and sustainer engines, 30 % of the pilots have had an engine failure after having performed a successful test run at the beginning of the flight. • 30 % of the pilots indicate that some kind of damage was done to the aircraft as a result of having and operating an engine.• Operational and Maintenance Difficulties: • Air-start time, difficulty, sink rate prior starting • Vibration, noise, heat, fuel, drive belts, etc.SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 3
  • 4. Electric Advantages• Reliable – electric motors usually start ! Safety still precludes air-start without field.• Fast air-start (Antares ~ 10 seconds)• Typically automated systems - easy• Low sink rate “engine out not running” (no cooling radiator) – lower decision height• Low vibration and heat – low maintenance• Negligible density altitude effect• Plenty of disadvantages too !SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 4
  • 5. Electric Power Issue: Batteries● Every battery is a trade-off: ● Energy density ● Cost ● Lifetime – Cycles, years ● Max discharge current ● Weight ● Safety ● Memory effects ● Temperature requirements● Battery Care and Feeding: Balancing, heating, cooling Significant complexity & cost.SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 5
  • 6. Energy Density of Batteries• Gasoline: 13 Kw*hr/lb, relative efficiency of gas/electric drive (.93/.15) or equivalent: ~ 2 kw*hr/lb effective energy• SAFT Lion 300 w*hr/lb as used in Antares*, around 1/7th effective energy/weight of gas• Nissan Leaf battery about the same, Kokam Lion about 90%.• Electric motor weight makes up only a bit...• Experimental batteries heading > 1kw*hr/lb Not yet real...SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 6
  • 7. Enough Math: Glider Issues• The energy you need to climb depends on aircraft weight; same for sustainer or SL.• After you start a gas sustainer, you may spend a long time climbing to get high enough before crossing the woods home.• Level flight takes much less power than climb• Battery is ~2/3 of e-propulsion weight & cost• Why make a e-sustainer ? Batteries need enough energy for a climb ! A powerful electric motor is inexpensive. If youre going to spend weight/cost for batteries, might as well make a self-launch.SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 7
  • 8. Real Performance• Distance in level flight specs sound great, But With full charge, and you will need to climb... • Cruise range specified as level / sawtooth Antares 20E example 76 / 103 nm • Youre low in the boondocks: Climb 3000 ft using ~1/3 of battery power, then cruise 70nm sawtooth using ~2/3 battery. • Published numbers assume you had a full- charge (ie took a tow to launch)• So far, no electrics for long-distance cruising: self-launch+reserve or sustainer only !SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 8
  • 9. Lange Antares 20E and 23E• High-end of glider performance and cost • Antares 20E: 56:1 Max L/D, >800 fpm climb-rate Typical 9000+ foot climb, >7500 at max gross • Antares 23E: 60:1 at 78 knots, ultimate for WGC Higher weight, lower climb altitude and rate• >70 delivered (> total of all other electrics)SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 9
  • 10. Taurus Electro 15m Side-by-Side• Compared to pure glider, gas or electric adds 50% to price.• With recommended optional larger battery: – 50 lbs heavier than gas-powered – Stated climb 6500 ft, or cruise ~ 1 hour• Big cockpit, easy to taxiSSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 10
  • 11. FES Configuration• Simpler than pylon, retrofit existing planes ?• No pylon drag engine not running, instant on• Drawbacks: Drag from prop (prop plus disturbed flow on fuselage), prop diameter• Retrofit Issues – Maybe not... • Weight of non-lifting parts may preclude retrofit • Structural complexity (batt), Round nose• Possibly a good solution for moderate performance sailplanes. Currently available on LAK-17B and Silent.SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 11
  • 12. Alisport Silent Electro (LAK FES)• Nose-mounted propeller 13.5m self-launch• Compared to unpowered glider, about: – 50% more expensive (less difference after trailer, instruments, and options) – 25% heavier (160kg-205kg electric-190kg gas)• Climb 5900 ft, or cruise 80 nmSSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 12
  • 13. LAK-17B FES• Contemporary 15/18-meter glider• Climb 3600 ft, or cruise 62 nm• Only adds 80 lbs over pure sailplane !• See the LAK-17B in the exhibit hallSSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 13
  • 14. Who Knows This Glider ?SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 14
  • 15. Have Aliens Invaded ?SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 15
  • 16. Who Knows This Glider ?SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 16
  • 17. What happened here ?SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 17
  • 18. 6000 km range ?SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 18
  • 19. Who Knows This One ?SSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 19
  • 20. Questions To Ask before buying...• Climb altitude at your weight ?• Cruise range sawtooth and level ?• Battery lifetime ?• Measured performance, power & glide ?• Make sure range meets your needs !• Number planes delivered to customers ?• Flight Trial available ?• Customer referencesSSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 20
  • 21. A List of Electric Gliders• Eric Raymonds SunSeeker, SunSeeker II• Lange Antares 20E and 23E, Schempp-Hirth Arcus E• Pipstrel Taurus electro G2, Apis E• Silent electric (original and FES)• LAK 17B FES• Waiex E• Experimentals: Pipistrel G4, Icaré II, eGenius, Solar Impulse, Lange H2 and H3, Lazair ESSA 2012 Convention Electric Gliders © Dave Nadler "YO“ 2012 Slide 21