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Boxwing
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Joined: Sun Jan 16, 2022 7:09 pm

Horizontal Stabiliser Angle of the Bristol 188

Sun Apr 24, 2022 3:08 pm

Hello,

I was reading about the Concorde and somehow ended up learning about the Bristol 188. While looking at pictures, I realised that the horizontal stabiliser had quite a downward angle. It is quite visible in this pictures:



Would somebody have more information why this is? The forces (as much as drag) generated due to such a design seem counterintuitive to me. Every help is appreciated.

Best,
Boxwing
 
zanl188
Posts: 4051
Joined: Sat Oct 21, 2006 9:05 pm

Re: Horizontal Stabiliser Angle of the Bristol 188

Sun Apr 24, 2022 4:55 pm

I don't know much about the 188. However I will suggest to you that the horizontal stab is probably trimmable. Perhaps the angle you see in the pictures is just where the stab was the last time the aircraft was powered down.
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 1:01 am

I think the OP might be referring to the significant anhedral, not the pitch angle of the stabiliser. At a guess, that would be to keep it out of the engine exhaust.
 
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Francoflier
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Joined: Wed Oct 31, 2001 12:27 pm

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 2:10 am

The whole stab was moveable. You can see on the few inflight pictures available online that it didn't have this angle while flying.
This was likely its ground/parked position, or just where it eventually came to a rest when hydraulic pressure was lost.

I suspect the broad supersonic range of speed it was meant to operate at necessitated large pitch authority, especially for things such as Mach tuck and other weird stuff that happens when going that fast with 'primitive' (i.e. pre-supercomputer) aerodynamic designs.
 
Yikes!
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Joined: Sat Oct 13, 2001 4:51 pm

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 2:24 am

Starlionblue wrote:
...At a guess, that would be to keep it out of the engine exhaust.


Agree.
 
DH106
Posts: 726
Joined: Wed Jun 15, 2005 5:32 pm

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 6:04 am

Starlionblue wrote:
I think the OP might be referring to the significant anhedral, not the pitch angle of the stabiliser. At a guess, that would be to keep it out of the engine exhaust.


Just for clarity - the tailplane is mounted high on top of the fin as a 'T' tail and has no (discernible) anhedral. Is it possible you're looking at the main gear struts here (like I did initially! :? )?
 
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Buyantukhaa
Posts: 2347
Joined: Thu May 13, 2004 5:33 am

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 9:31 am

DH106 wrote:
Starlionblue wrote:
I think the OP might be referring to the significant anhedral, not the pitch angle of the stabiliser. At a guess, that would be to keep it out of the engine exhaust.


Just for clarity - the tailplane is mounted high on top of the fin as a 'T' tail and has no (discernible) anhedral. Is it possible you're looking at the main gear struts here (like I did initially! :? )?

Indeed:
Image
 
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Starlionblue
Posts: 21266
Joined: Fri Feb 27, 2004 9:54 pm

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 9:58 am

DH106 wrote:
Starlionblue wrote:
I think the OP might be referring to the significant anhedral, not the pitch angle of the stabiliser. At a guess, that would be to keep it out of the engine exhaust.


Just for clarity - the tailplane is mounted high on top of the fin as a 'T' tail and has no (discernible) anhedral. Is it possible you're looking at the main gear struts here (like I did initially! :? )?


Aaaah!

Yes I see it now!

Extra shame points for me since I have actually seen this exhibit in real life... :rotfl: :rotfl: :rotfl:
 
kalvado
Posts: 3790
Joined: Wed Mar 01, 2006 4:29 am

Re: Horizontal Stabiliser Angle of the Bristol 188

Mon Apr 25, 2022 11:30 am

Isn't tail mounted stabilizer supposed to have negative AoA in level flight in all planes? It is due to stability considerations, what would happen if wing stalls at high AoA, center of gravity vs center of lift, and wing stalls first or stabilizer stalls first, etc.
Nose mounted stabilizer may be lifting one, but that opens can of worms with stability.

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