real B1900, why on earth all the stabilizers??

[Guest pez_man]

Hi folks! I've been driving around in my B1900 for a couple of days now, a FANTASTIC plane! As I've been panning around it in spotview looking at the great exterior, I've been thinking about all the extra wings at the rear of the plane. First you have the ordinary hstab, then the small extra fins going down from it, plus a lower set of hstab looking wings PLUS the "learjet" style fins at the bottom, I hope you get what I mean! It seems that it must be some kind of serious aerodynamic problems with the a/c when it needs all this extra stuff, or?? Does anyone out there know the story behind it? I'm just curious! rgrds/fredrik granfors

[CF104 0]

Hi Fredrik,Without digging into it in depth I would have to say the extra stabilizers were due to the added fuselage area affecting directional stability. They do appear to be after thoughts making me believe they were added during flight testing. Otherwise, I think they would have just enlarged the V and H stabs. Anyone out there with early photos of the 1900 prototype?JohnBoeing 727/737 & Lockheed C-130 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

[Guest pez_man]

Hi again!I've been nosing around the pprune-forums searching for some answers about this, and apparently beechcraft wanted to use as much parts from the king air 350 as possible, so apparently it's the king air tail that's used, thus the need for extra stabilization due to the extra fuselage length, just as you suggested John... Some pilots seems a bit p/o about this costhunt, since a lot of other 350-parts are used in the b1900 that aren't working very well with the larger b1900 and its harder use use as an airliner... Perhaps some rw b1900 pilot could chime in here?? :-) cheers!/fredrik

[Qavion 19]

"thus the need for extra stabilization due to the extra fuselage length,"Interesting.... The 747SP had it's Stabilizer/Rudder surface area increased because of the reduction in fuselage length.Can both be right?Cheers.Ian.

[brucek 38]

Less leverage from the Center Of Lift?Hi Ian- good to "see" you!Bruce.

[Guest ricecake]

Kind of a shot in the dark here but I

[CF104 0]

Hi Evan,You're right in respect to the 2 lower inverted V ventral fins regarding deep stalls and T tails. These were required due to the current FAA certification rules concerning FAR part 23 and deep stall recovery/controlability. It's much the same as the newer Lear family of buisiness jets with the inverted V stabs.The smaller fins are for directional stability and really wouldn't have much effect getting you out of a deep tail stall.As far as needing more V and H stab surface due to fuselage area, It's much the same as why a lot of float planes require extra fins when floats are installed, ie. Twin Otter, Single Otter, Cessnas with the added ventral fin etc..... The floats add more surface erea and the aircraft needs the extra fins for directional stability.As for the 747SP, the larger fin was required because of the reduction in moment with the shorter fuselage.JohnBoeing 727/737 & Lockheed C-130 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

[Qavion 19]

Thanks, John... Makes sense now. I read "length" instead of "area" (I think Fredrik did, too?).Cheers.Ian.

[Guest pez_man]

Yes I did, but it all seems a bit clearer now, thanks a lot!rgrdsfredrik