vertical stabilizer

C

cheezyflier

Charter Member
it's one of those questions i have been meaning to ask for years but only remember when i'm not here.

some stabilizers are straight up, some on an angle is there a purpose for the angle besides that it looks cool?
 
cheezyflier said:
it's one of those questions i have been meaning to ask for years but only remember when i'm not here.

some stabilizers are straight up, some on an angle is there a purpose for the angle besides that it looks cool?
Click to expand...

Cheezy, a vertical stabilizer is use for yaw stability it works with the rudder (moving part or the vertical stabilizer) and elevators or stab. The old Beech Bonanzas used a combination elevator/rudder system with its two angled stab-a-lators. They worked as both a rudder and elevators.

It was later abandoned by Beech in favor of the traditional vertical stab and elevator combination due to control problems in certain conditions.

You will find some aircraft, such as the F-4 Phantom that have downward angled elevators and a vertical rudder/stabilizers combination.

I hope this helps you.
 
I think angled horizontal stabilizers are to get them out of disturbed airflow? Maybe add a little extra yaw stability without increasing the vertical stabilizer size?

As for vertical stabilizers... maybe extra pitch stability? Stealth?

I really don't know. I'm having fun hypothesizing though. Maybe some in the know will come along and let me know how wrong I am. :icon_lol:
 
this is what i mean:

tails.jpg


see the differences? are they for looks or do they have some purpose ?
 
If I remember correctly, an elliptical airfoil shape minimizes drag. However, design and ease of construction are often an overriding factor for this. A close approximation is often good enough, and allows for certain "stylistic" design choices. Once again, I am not sure. I'm hoping an aerospace engineer will speak up. :mixedsmi: (I also think at transonic or supersonic speeds, an overall swept back design is preferable!)
 
Couple of reasons (CPL recently so I still remember lol!)

-Streamlining
-Looks cool
-But mainly because it shifts the effective location of the rudder aft, lengthening the moment arm between the aircraft's CoG and the rudder allowing rudder effectiveness to be maintained at more rearward CoG locations. This means it is both safer in general and allows the rear CoG limit to be further aft (more weight can be put in the back!)

Hope this answers your question!
 
Whitehawk said:
Couple of reasons (CPL recently so I still remember lol!)

-Streamlining
-Looks cool
-But mainly because it shifts the effective location of the rudder aft, lengthening the moment arm between the aircraft's CoG and the rudder allowing rudder effectiveness to be maintained at more rearward CoG locations. This means it is both safer in general and allows the rear CoG limit to be further aft (more weight can be put in the back!)

Hope this answers your question!
Click to expand...

Much more elegant than my answer :)
 
Cheezy,
Compare the pic below to the pic I posted in my "Vintage Seaplane Shot" thread further down the page. This is the XPB2Y-1 prototype with mini-fins retrofitted to the original tail to fix the yaw stability problem, didn't work so they went to the twin vertical stab design used on the production aircraft. The increased dihedral angle of the horizontal stabs probably helped as well. Good example of how design problems get worked out in prototype versions.

Consolidated_XPB2Y-1_1938.jpg
 
Cratermaker said:
If I remember correctly, an elliptical airfoil shape minimizes drag. However, design and ease of construction are often an overriding factor for this. A close approximation is often good enough, and allows for certain "stylistic" design choices. Once again, I am not sure. I'm hoping an aerospace engineer will speak up. :mixedsmi: (I also think at transonic or supersonic speeds, an overall swept back design is preferable!)
Click to expand...

Then I offer you Dan Raymer's notation regarding tail design:

http://www.adac.aero/Documents/Raymer_Annotations/4.5_Tail_Geometry_and_Arrangment.pdf

[FONT=Trebuchet MS, Arial, Helvetica]Dan Raymer's book "Aircraft Design: A Conceptual Approach" is the textbook for many aircraft design capstone undergraduate courses. It covers almost all aspects of conceptual design, including initial sizing, configuration layout, aerodynamics, propulsion, stability & control, mass properties, and structures and materials. [/FONT]

The complete Annotations can be found at http://www.adac.aero/index.htm
-just click on the "Raymer Annotations" button at the top of the page.

Rob
 
On T-tailed planes, sweeping the fin/rudder places the horizontal stabs/elevators further aft, with the benifits discribed by Whitehawk.
Look at the MiG-15 for example.
 
Also size and area had 'some' effect on speed, so air racers would have smaller rudders, but if you raked them back too extreme, they lost their 'bite' in the air, rushing the wind 'over' the top of the 'rudder' zone. Wittman was talking on this in some interviews long ago, back around his racing days. He could look at a rudder and tell you how efficient it was.



Rudders are a bit tricky to design into an aircraft, from what all I have gathered..

Another wierd one, (speaking of tilted vertical stabilizers), the first Stealth fighter had rudders almost meeting at the top. This was for deflecting radar into the sky. But they were useless for flight from the airflow over the crafts body, causing one crash in a prototype. They were then switched outward, like a V tail, as like a Bonanza.


The Bellanca Super Viking or Viking had a HUGE tail area (rudder) which started nearly where the baggage area was, up to the tip. You can always find a Viking in a group of planes. The biggest rudder around on small planes. The reason was so that it wouldnt spin. They wanted to get rid of the tripple rudders, and their trademark was 'no spins'.


Bill
 
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