lockheed Jetstar pitch trim

[stilton]

This aircraft had a unique (as far as I know) pitch trim system. The entire vertical fin 'tilted' forward and back thereby adjusting the fixed horizontal stab.

Never seen this before or since on any aircraft, anyone know the reason (s) why Lockheed designed it this way ?

[dixi188]

Don't know why Lockheed did it that way, but it may have been to allow an available, but large, actuator to be fitted in the rear fuselage.

Another type that has this is the Mooney light singles, if I remember correctly.

Cheers.

[con-pilot]

Never seen this before or since on any aircraft, anyone know the reason (s) why Lockheed designed it this way ?

I believe that I was told why it was designed that way in initial school, but for the life of me I cannot remember why. Sorry.

There were some other different designed systems on the Jetstar as well. There was a 'Mach trim' system separate from the auto-pilot system that you turned on before takeoff and off on shut down, I don't why that was either. Also, I don't believe that there was a standard door/stair design either.

Now the most interesting design concept, well to me anyway, was the leading slats. They had to deploy for takeoff, but if they failed to extend on landing there was no speed penalty. If V-Ref was 115 kts with slats, it was still 115 kts with no slats. Even with the slats the Jetstar loved runways. Same with the speed brake under the tail of the aircraft, dang near useless.

However, I loved flying the Jetstar. One of the nicest flying aircraft I ever had the pleasure to fly.

[411A]

One of the nicest flying aircraft I ever had the pleasure to fly.

Certainly true, after all...it's a Lockheed... very well designed.
Speaking of the particular design, I was told, many years ago, by a Lockheed senior design engineer on the JetStar....it was designed so that a pilot, who had only flown a twin Beech before, could slide right on into the LHS, and feel right at home.
IE: fine handling qualities, quite unlike the LearJet, which came just a bit later.
But, you had to understand the systems, for best results.
Yes, the original JetStar sucked up fuel like a big Hoover, but with the Garrett engines, a very good performer.
Built like a tank (with chem-milled wing skins, similar to the Sabreliner), but flew like a much lighter airplane.
Also, seem to remember...you had to test the mach trim system prior to each takeoff, and if interrupted mid way through the test, and forgot about it...on takeoff the stab would trim nose up, unexectedly.
This would get your attention, in a hurry.

[glhcarl]

This aircraft had a unique (as far as I know) pitch trim system. The entire vertical fin 'tilted' forward and back thereby adjusting the fixed horizontal stab.

Never seen this before or since on any aircraft, anyone know the reason (s) why Lockheed designed it this way?

I think you will find that the same type pitch trim system was used on the Lockheed XF-90, which was also a Kelly Johnson design. It was simple and effective, which Kelly liked.