Possible Clues:

• Idler struggling with gravity first, it has no power to fly
• It may require several drafts
• Cover fitted in German plane
• Flying machine without engine
• Might Reg turn around the cover without a motor?
• German taking cover from aircraft
• Is the girl about to get the editor back without the aid of an engine?
• Girdle for silent flier
• It's taken off to get rid of a leg without the help of a motor
• Grand being on top, and on Queen's aircraft