2 Tails better than 1

[untitled]

Salaam

Me Again.....
Any of you guys aerodynamics gurus ?

I want to know what effect on a airframe does have having 2 engines and 2 vertical stabilizers?

I know F/A 18, F-22, F-15, F-14, Mig 29, Su27 family (with exception of Su 34 .... i might be wrong) are all aircraft with the above features, all having excellent maneuverability, range and agility.......... The only exception to these rules seem to be the Mig 25/31 and SR 71 (and YF-12 its fighter equivalent).

Then we see a broad range of performance in aircraft with single vertical stabilizers and twin engines. This range starts from good (F4 Phantom, Mig 19, Su 15, jaguar) .... To bad (Tornado, A -5 Vigilante, F-111)... I know the Tornado F1 is a fighter but it is sad it lacks the agility of a true fighter.

Can anyone elaborate ???

Thanks

 

[x_man]

Well ,not an aerodynamicist but will add my two bobs worth here...

Before we venture into two tails, the obvious question that comes to ones mind is why even one tail or what’s the function of a tail??…Well it provides stability and used to control yaw by mean of a rudder (which is generally located at the rear end of the stabilizer...)

If you have observes, tails come in all shapes and sizes…e.g. very high, very short , single, twin, three or even four tails, H-shaped ( A-10) , V shaped ( F-117), T-tail , E-tail etc etc…..No matter what’s the shape or number , their basic function remains ( almost) the same…to provide direction stability and control yaw..

Why two tails…well there can be million reasons…each aircraft is different from other due to its design, role and requirements….The reason to incorporate the twin tails can be :-

1. Basically, due to structural reasons---i.e. weight/strength ratios sometimes it is easier to satisfy this requirement with two tails-increase direction control in low airspeed..

2. Reduction in overall aircraft height...

3. Instead of using one enormous tail, it would be appropriate to use two small tails in case of an engine out on takeoff or flight….If you have noticed, F-15,F-14, F-18, SR-71, Mig -29/25 , their engines are well separated from each other….imagine the yaw or the directional problems in case of one engine failure….These aircrafts would be difficult to control with one tail ( or rudder..)

4. Considerations while keeping in mind an aircrafts’ spin characteristics….. F-15,F-14, F-18 etc are capable of reaching extreme angles of attacks where a single tail would be blanketed by the fuselage.

5. Redundancy /survivability ( e.g. in case of A-10, survivability through redundancy was a significant design issue because A-10 was supposed to operate at low altitudes due to its role... It was designed to lose a significant chunk of tail, or have control cables to one side shot out, and still be flyable…)

6. Twin tales also have to do with shedding vortices from the wing root that single tail would be ineffective due the surrounding airflow.

So you see that one can go on and on while considering the effects of single or twin or three tails but in the end it all comes down to the aircrafts role that actually dictates its design requirements…

You have also mentioned about reduced manoeuvrability of A-5, F-111 etc…Well again role dictates this trait as well…For obvious reasons, the Air superiority fighters are always more agile than bombers or ground attack fighters…I don’t think it needs any further explanation…

 

[untitled]

thanks x man

we see another example ..

The F-35 and Yak 141 ....... Both single engined but having two vertical stabilizers

 

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X man F-111 was originally designed as a fighter .........
but could not compete with Phantom ..... only then did the American Navy start work on the F-14.

 

[zavis2003]

two tails are good coz aik dum kat b jay tou tou pilot dosry hala skay