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Eurofighter double vertical stabilizers


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What was the reason behind resignation from double vertical stabilizers on Eurofighter?

 

Some EF prototypes had double stabilizers. And final EF has somewhat restricted high AoA regime due to having single vertical stab.

Plus double canted stabs will give smaller radar reflection from the side.

Even drag of one bigger and wider stabilizer could be bigger.

 

It was due to financial reasons or there was some aerodynamics behind this decision?

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It would be interesting to know why the final version went with the single stabilizer but for aesthetic reasons, I prefer the form and shape it is currently.

Prettiest design of modern jet fighter from my perspective.

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And final EF has somewhat restricted high AoA regime due to having single vertical stab.

Interesting, haven't heard that so far. How exactly is the EF limited in AoA?

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Interesting, haven't heard that so far. How exactly is the EF limited in AoA?

 

 

As far as I understand it, the location of the canards is far enough forward compared to the wing that they don't generate your typical delta wing vortexes all that efficiently, unlike e.g. the Rafale. That means that at high AoA the wing isn't as efficient as other designs in generating lift, making the aircraft AoA-limited kind of like the Viper (but probably better than that).

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All F-16, EF, Rafale, Gripen are somewhat limited in max AoA available due to single vertical stabilizer which is in fuselage shadow when AoA is greater than some 25-35°.

(Unlike i.e. Hornet, F-15, Su-27, F-22, F-35 with wide double vertical stabilizers remaining controllable at much greater AoAs.)

 

 

EF - unlike the others - at the initial stage of development has double stabilizers, idk what was the reason of abandoning that solution later on, except for financial reasons.


Edited by bies
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/-----------------------/-----------------------------/--------------------------/

Ok, I've received the answer somewhere else.

It was due to financial reasons. Messerschmitt-Bölkow-Blohm developed tail section with double vertical stabilizers allowing extreme AoA capabilities but due to financial cuts modified Tornado tail section had been used.

 

Other than that Germans wanted pure air to air platform when the British wanted multirole and they were less interested in extreme agility.

/-----------------/-----------------/------------------/

 

This decision was first explored on the ACA / EAP.

 

Warton (BAE) did extensive trade studies on one versus two tails in 1982 and felt the performance benefit to the ACA configuration was minimal and outweighed by additional weight and compexity. High alpha capability was an MBB obsession and not a major concern for BAE or the RAF.

 

For EAP the initial plan was MBB doing centre fuselage and vertical tails, and AIT the rear fuselage, but then BAE had to take these over when the other partner nations cut funding and went with largely Tornado rear fuselage including a single Tornado fin. It worked well enough on EAP.

 

When EFA design was finalised, two versus one tails was re-examined again, but the same conclusion was reached as before. For the given requirements, low drag and weight and adequate stability was the right solution.


Edited by bies
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/-----------------------/-----------------------------/--------------------------/

Ok, I've received the answer somewhere else.

It was due to financial reasons. Messerschmitt-Bölkow-Blohm developed tail section with double vertical stabilizers allowing extreme AoA capabilities but due to financial cuts modified Tornado tail section had been used.

 

Other than that Germans wanted pure air to air platform when the British wanted multirole and they were less interested in extreme agility.

/-----------------/-----------------/------------------/

Interesting, thanks :thumbup:

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There would also be a slight weight penalty too, as the double stabs would not be half the length of the single, but a bit more. Also, instead of a single mounting point, you'd have two mounting points, requiring two areas of the airframe with extra strength and reinforcement.

 

As beneficial as high angle of attack flight would be to a fighter, I think the stealth benefits would be of greater interest... but then maybe it's not that big a difference in RCS to be a big consideration. Especially since the RCS isn't the same from all aspects.

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The original TKF proposal from MBB had a single fin and convetional delta wings. This baseline was enhanced as a result of wind tunnel tests introducing the cranked delta and twin fins, along with many detail changes concerning fuselage and intake shaping, foreplane planform and the introduction of vary cowls on the intake lips.

 

For the EAP technology demonstrator the single fin was indeed owed to budgetary constraints after Germany and Iraly pulled out of the ACA which was based on the TKF configuration. The eventual omission of the twin fins was first and foremost owed to the added structural weight and the return to plain deltas was owed to ease of manufacturing and a supposedly lower RCS (whatever the actual difference was). IMO the original configuration was aerodynamically superior and it's no coincidence that the proposed aerodynamic modification kit (AMK) introduces wing apec strakes or LEX to partially mitigate the longitudinal/directional stability issues of the current configuration at higher AoAs. The Typhoon has indeed a very modest AoA limit which limits its nose pointing authority and maneuverability at low speeds. Right now the FCS imposed AoA limit also constraints the aircraft's ITR performance as the AoA limit is below CL max.

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  • 2 weeks later...
Its not just financial costs, they found when they used the airbrake the airflow between twin stabs required them to be significantly stronger and thus heavier at a time when the program was desperate to reduce the weight of the project.

 

And now they have the problem that the wake turbulences of the airbrake adersely impact fin fatigue. The solution would have been foreplane detrim, split flaperon and/or rudder for braking.

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  • 6 months later...

Mainly due to budget cuts. The Eurofighter was designed during the Cold War to defeat the Soviet MiG-29 and Su-27 in dogfights over Europe in 1990s.

 

When the Eastern Bloc collapsed and the mighty Soviet military machine crumbled, the threat disappeared. Nobody was interested in investing in a super maneuverable dogfighter anymore because there was no one to dogfight with.
The Eurofighter itself was supposed to enter service in the mid-1990s, but after the collapse of the USSR, resources were drastically reduced and the plane entered service only a decade later in pains and stripped of the most radical ideas, there were even thrust-vectored tailless designs considered.

(Like F-22, the cheaper variant of the two, with cheaper engines, without many originally designed systems, trading additional mass increase for lower cost and cutting original order from 700 to some 190 planes, barely saving the program at all)

 

The biggest opponent in the history of Eurofighter (also the F-22) was the collapse of the USSR and the disappearance of the capable enemy, which they could possibly fight.


Edited by Berserk
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No double tail thus no very high AoA regime, no thrust vectoring, mechanical radar antenna instead of E-scan, no IRST for german fighters, various Praetorian DASS features missing in different series, i'm mentioning a only few features speaking from memory. I've read some interesing book about the whole Eurofighter developement program, but it was years ago and what I remembered after 1990 were constant budget cuts, delays, restrictions, withdrawing from various costly solutions, limiting the number of planes, even more delays, especially the German side seemed to be counting money. At one point, the entire program was in question at all. After the Soviets collapsed and the danger was gone Germany were engaged in reunification process, not in some costly military projects of smaller importance.

 

Meanwhile, air combat was changing, as Eurofighter's design began in early 1980s it was not entirely clear that beyound visual range combat would become so reliable and dominant so quickly with the introduction of the AIM-120 missiles and rapid computer technology advances. A classic, very high-performance maneuver fighter with only a slight reduction of radar reflection was still being designed. That's why even what left will surely be very interesting fighter in the DCS.

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Some perspective and context needs to be added to your perception.

1.) The twin fins are not the primary reason for the aircraft's limited AoA performance, but could have helped.

2.) TVC was not a requirement at all, so it wasn't cut.

3.) M-Scan was a sensible choice at that time, as the AESA technology wasn't mature and utterly expensive. That the aircraft still lacks such a system in 2021 is without doubt a serious drawback.

4.) The incremental build up of capabilities is common practise in all military aircraft programmes, so the lack of certain DASS elements in earlier aircraft was not owed to cuts or omissions.

5.) The lack of PIRATE on German or Austrian aircraft is the politically owed decision of these nations, but the sensor is available.

 

Actual cuts comprised airframe structural strength, nuclear hardening requirements relaxion, cancelatiin of several AG weapons and 1500 l drop tanks, limiting the use of FO databusses, omission of a maintenance datalink and IR signature reduction measures for the EJ200. There were more ambitous plans about the scope of the DASS fit (incl. a fin tip pod mounting additional equipment) and the budget for national equipment on top of the baseline configuration. There might have been other things, but those you have listed are not among them.

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The twin fins of the demonstrator were more likely dropped for other (very good) reasons.

 

The main thing which interests me about the earlier Eurofighter plans was the greater variety of 1990s armament (including unguided air-to-ground weapons) that never saw service because the Cold-War ended. If the original timeline had taken place we would've seen rockets (and some other fun systems) that became outdated by the time the Eurofighter entered service in any numbers. They'd be nice to have for a 'late Cold War' scenario based on the environment it was actually designed primarily for (i.e. 1990s Europe)... but iron bombs and rockets might be too much to wish for.

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On 3/19/2021 at 9:59 PM, Spectre11 said:

Some perspective and context needs to be added to your perception.

1.) The twin fins are not the primary reason for the aircraft's limited AoA performance, but could have helped.

2.) TVC was not a requirement at all, so it wasn't cut.

3.) M-Scan was a sensible choice at that time, as the AESA technology wasn't mature and utterly expensive. That the aircraft still lacks such a system in 2021 is without doubt a serious drawback.

4.) The incremental build up of capabilities is common practise in all military aircraft programmes, so the lack of certain DASS elements in earlier aircraft was not owed to cuts or omissions.

5.) The lack of PIRATE on German or Austrian aircraft is the politically owed decision of these nations, but the sensor is available.

 

Actual cuts comprised airframe structural strength, nuclear hardening requirements relaxion, cancelatiin of several AG weapons and 1500 l drop tanks, limiting the use of FO databusses, omission of a maintenance datalink and IR signature reduction measures for the EJ200. There were more ambitous plans about the scope of the DASS fit (incl. a fin tip pod mounting additional equipment) and the budget for national equipment on top of the baseline configuration. There might have been other things, but those you have listed are not among them.

 

Airframe structural strength? In what way?

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