PPRuNe Forums - View Single Post - Why is there such a big difference in design philosophy of a prop vs. jet aircraft re
Old 15th Feb 2009, 16:13
  #6 (permalink)  
Bullethead
 
Join Date: Nov 1999
Location: East side of OZ
Posts: 624
Received 0 Likes on 0 Posts
The 707 had tail anti-icing,
The B707-338s I flew didn't have it yet the C130Hs I flew had wing, tailplane, rudder and engine thermal anti-ice. Hot bleed air, and turning it all on was like losing an engine it used so much bleed air.

The significant design difference between most turbo prop aircraft and most, if not all, swept wing jet aircraft is that the the turbo props have a fixed tailplane and an elevator whereas the jets have a movable tailplane and an elevator.

Because the jets have this feature where the whole tailplane is moved when trimming in pitch the problem of high incidence on the tailplane is avoided and so therefore the problem of tailplane stalling. Ice will still build up on the tailplane but because the whole tailplane moves when trimming the aircraft you still have adequate pitch control and so no requirement for tailplane anti-icing.

On the B707, full elevator deflection was equivalent to about four units of pitch trim and there were more than twelve units of pitch trim available. A very powerful control.

Regards,
BH.
Bullethead is offline