stabilizers versus elevators

[zhopalu]

why do some airplanes have an elevator (with a trim tab), while others have a horizontal stabilizer that is used to trim the elevator forces? size of the airplane is surely not the deciding factor because i know of both light & heavy class of aircraft that have a stabilizer, at the same time there are medium class aircraft that do not have a stabilizer but just an elevator with a trim tab. any answers?

 

[trafficinsight]

Designer liked the way it looked

 

[///AMG]

Higher speed aircraft typically use all moving stabilators in place of elevators, especially aircraft designed to fly in the transonic/supersonic range. I believe the F-86 was one of the first aircraft designed with this feature, for this exact purpose. Then again, I guess the Piper Cherokee family would kind of counter this point, so maybe it just depends.

 

[trafficinsight]

In the Cherokee's case it was all parts count

 

[Zondaracer]

As AMG pointed out, a stabilator doesn't jam up in super sonic flight like an elevator... But on your non-trans/super sonic aircraft like Pipers, a stabilator is easier to balance, reducing chance of flutter, and reducing the force input required.

http://en.m.wikipedia.org/wiki/Stabilator

 

[Cessnaflyer]

Since there is more surface area you can shrink the chord and the span at least that's what the Beech engineer told me about using them for the Sports and Sundowners.

 

[cmill]

Because some engineer wanted us to think extra long and hard about it, when he really just flipped a coin to decide.

 

[trafficinsight]

Seriously, the whole Cherokee stabilator is only like 12 parts.

 

[Roger Roger]

Seriously, the whole Cherokee stabilator is only like 12 parts.

A friend of mine recently had one apart to replace a cracked skin. He showed me the insides. I was like...."that's it?!?"

 

[trafficinsight]

It's then that you realize those beads stamped into the skin are actually important

 

[HVYMETALDRVR]

Engineers call it TLAR... That Looks About Right...

 

[Roger Roger]

It's then that you realize those beads stamped into the skin are actually important

Aileron on the Cherokee Six has 10 pieces not counting the hinges. 2 ribs, one spar, a 3 piece pushrod attach point, 2 doublers, the skin, and the counterweight.

 

[trafficinsight]

From what I remember the Cherokee had around half the number of parts the Commanche did. They built them in parallel for a few years with the Cherokees being built in Vero Beach and the Commanches being built in Lock Haven. Then a flood destroyed the Lock Haven plant and that was the end of the Commanche.

 

[mshunter]

There is the increased drag factor of having a trimtab hanging out in the breeze. There is a reason that some Reno racers change the incidence on the tail. But if you get something capable of cruising in the mach you also have a better way of not worrying about the shockwave making the elevator useless. Think about the mods done to the Bell X1. Yeager found out that the elevator was useless above a certain speed. The farther back that shockwave goes the less effective the elevator becomes.

 

[zhopalu]

Thanks for the response folks. While the reason for having it on high speed aircraft is understood, I know of at least one slow moving aircraft (Dornier 228) that has a stabilizer.

 

[Mike H]

I was once told that one reason they went with the stabilator in the Cherokee was that it allowed them to build a somewhat shorter fuselage than if they'd gone with a traditional stabilizer/elevator combination