B-17 Tail Structure

Does anybody know the reason why they changed the empennage on the early B-17s?
I was watching the History Channel earlier today and wondered why they added the
heavy strake to the tail. I admit the early B-17s looked like the tail would
come off if stressed too much. Did this actually happen or was it a
controllability issue for engine-out situations?


--
Mortimer Schnerd, RN


http://www.mortimerschnerd.com

In article ,
"Mortimer Schnerd, RN" wrote:

Does anybody know the reason why they changed the empennage on the early
B-17s?
I was watching the History Channel earlier today and wondered why they added
the
heavy strake to the tail. I admit the early B-17s looked like the tail would
come off if stressed too much. Did this actually happen or was it a
controllability issue for engine-out situations?


A lot of the change came from adding the tail-gun position.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

Does anybody know the reason why they changed the empennage on the early
B-17s?

For greater directional stability and to strengthen the vertical tail. I think
the larger tail was first tried on later production B307s and then retrofitted
to the earlier 307s before being used in B-17F production.

CB

Subject: B-17 Tail Structure
From: (Jinxx1)
Date: 11/14/03 3:12 PM Pacific Standard Time
Message-id:

Does anybody know the reason why they changed the empennage on the early
B-17s?

For greater directional stability and to strengthen the vertical tail. I
think
the larger tail was first tried on later production B307s and then
retrofitted
to the earlier 307s before being used in B-17F production.

CB



Some guys I spoke to during the war who flew both the early andthe later
B-17's claimed that the earlier models just didn't have enough rudder.


Arthur Kramer
344th BG 494th BS
England, France, Belgium, Holland, Germany
Visit my WW II B-26 website at:
http://www.coastcomp.com/artkramer

"Mortimer Schnerd, RN" wrote in message Does anybody know the reason why
they changed the empennage on the early B-17s?

The change was made, starting with the E-Model, to improve stability at
high altitude.

Well, the tail did have to get bigger to add a rear gunner:
the very early models were tail-gun-less.
I couldn't say off hand if there were other issues.

"Mortimer Schnerd, RN" wrote in message
. ..
Does anybody know the reason why they changed the empennage on the early
B-17s?
I was watching the History Channel earlier today and wondered why they
added the
heavy strake to the tail. I admit the early B-17s looked like the tail
would
come off if stressed too much. Did this actually happen or was it a
controllability issue for engine-out situations?

The 307 had the same vertical tail as the early B-17s. A 307 was lost
in the late 1930s during a demo flight for KLM. The cause was traced
back to rudder lock - at very low airspeeds and high rudder deflection,
the hinge moment of the rudder could reverse. As a result, the pilot
couldn't center the rudder. It was found in wind tunnel testing that
the addition of a dorsal fin would prevent this. The dorsal fin would
shed a vortex, preventing rudder lock. The 307s were retrofitted with a
dorsal fin and the B-17s got one too.

After the crash, KLM vowed to never buy a Boeing product. They finally
broke this vow when they bought 747s.