Jump to content
Main menu
Main menu
move to sidebar
hide
Navigation
Main page
Contents
Current events
Random article
About Wikipedia
Contact us
Donate
Contribute
Help
Learn to edit
Community portal
Recent changes
Upload file
Languages
Search
Search
Appearance
Create account
Log in
Personal tools
Create account
Log in
Pages for logged out editors
learn more
Contributions
Talk
Download as PDF
English
Tools
Tools
move to sidebar
hide
Actions
General
Upload file
Special pages
Printable version
Get shortened URL
Download QR code
Appearance
move to sidebar
hide
Contra-rotating propellers
Download as PDF
Contra-rotating_propellers.pdf
Download
