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CDGIAD
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Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 8:51 pm

Does anybody know why no airliner with a V tail was ever built?
Only a few general aviation aircrafts have V Tail like the Beechcraft Bonanza.

V tail have one less part, in the era of weight saving
Obsession why aren't there more planes like that?
 
WN732
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Re: Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 9:31 pm

V-Tails can be temperamental. It was found that fuselages had to be extended longer than the conventional airplane design normally allowed. Otherwise they could be subject to "snaking." It was found that the advantage/disadvantage was moot and the added cost of design plus the possible need for a more fortified and longer structure would outweigh any weight and parts savings.

The Bonanza proved that it was doable but it did come with abundant cost. V Tailed Bonanzas were more susceptible to inflight overstress breakups than their conventional partners.
 
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ClipperYankee
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Re: Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 9:53 pm

I used to work at a Beechcraft parts dealer and shipped many a kit for strengthening V-tail Bonanzas back in they day when the model was in crisis.
We used to joke with the Beech people in Kansas about marketing a V-tail King Air and our parts rep there would get a good chuckle out of it. Since a few small airlines used King Airs (and probably still do), there's your V-tail airliner.
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GalaxyFlyer
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Re: Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 10:14 pm

Simple answer:: airliners are twins, tris or quads and each requires a powerful rudder for the OEI case. Imagine the Vmcg and Vmca for a V-tail B777?


Gf
 
nagpaw
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Re: Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 10:46 pm

How about the Beech Model 34 "Twin-Quad?"

https://en.wikipedia.org/wiki/Beechcraft_Model_34
 
GalaxyFlyer
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Re: Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 10:50 pm

Right, a failed old Part 23 or, at best, CAR 4b piston Beech of which one was built and it crashed.
 
nagpaw
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Re: Why no commercial aircraft with V-tail ?

Thu Oct 31, 2019 11:11 pm

Just trying to stimulate conversation, GalxyFlyer. I see you're not interested. Never mind. :smile:
 
GalaxyFlyer
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 12:27 am

The conversation is technical by nature, how to design a certifiable, aerodynamically sound airliner. It’s subject to a rather clear cut answer, then what conversation are you looking for? I’m interested enough to provide an answer proven to be correct over the last 70 years.

GF
 
UA735WL
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 12:41 am

I know that the rigging for a V-tail Bonanza is more complicated than that of a conventional tail airplane. I suppose in this day and age of fly-by-wire and independent control surfaces that particular problem could be mitigated. I suspect the reason the V-tail never took off was complexity, from both a control and structural standpoint.
"One test is worth a thousand expert opinions" -Tex Johnston
 
aklrno
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 12:49 am

Lots of military aircraft have angled tails but they have two special cases not required by civilian aircraft. The angled tails have reduced radar cross sections and fit better in the hangar deck of an aircraft carrier. Rather than ask why they don't have a v tail, maybe ask why they should have one.
 
26point2
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 1:57 am

GalaxyFlyer wrote:
Simple answer:: airliners are twins, tris or quads and each requires a powerful rudder for the OEI case. Imagine the Vmcg and Vmca for a V-tail B777?


Gf


The Fouga CM 170 Magistar wasn’t an airliner but it was a twin jet with v tail.
 
WN732
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 1:59 am

26point2 wrote:
GalaxyFlyer wrote:
Simple answer:: airliners are twins, tris or quads and each requires a powerful rudder for the OEI case. Imagine the Vmcg and Vmca for a V-tail B777?


Gf


The Fouga CM 170 Magistar wasn’t an airliner but it was a twin jet with v tail.


The thrust is almost centralized in one spot. On an airliner there would be a ton of yaw from one side.
 
nagpaw
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 2:26 am

GalaxyFlyer wrote:
The conversation is technical by nature, how to design a certifiable, aerodynamically sound airliner. It’s subject to a rather clear cut answer, then what conversation are you looking for? I’m interested enough to provide an answer proven to be correct over the last 70 years.


The OP asked "Does anybody know why no airliner with a V tail was ever built?" Well, there was a v-tailed airliner built: the Beechcraft Model 34. The "Twin Quad" was apparently an adequate airplane but was another victim of postwar market saturation. There's no mention of poor OEI handling qualities that I can find.

So what's stopping someone from producing a similarly-sized design today? There is apparently some way to fly a multiengined airliner with a v-tail. Said "airliner" doesn't have to be the size of a 777. :cheerful:

Edit: Hmm. I just reloaded the page and few answers showed up that I wasn't seeing before, specifically post #2 which eloquently answers my question. Ah, well. :lol:
 
GalaxyFlyer
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 3:04 am

It’s inefficient, simpler, more powerful controls can be designed when they do ONE task (yaw or pitch) control. The F-18 uses the rudders via the FBW to increase pitch authority for rotation off the ship at low speeds.

GF
 
reltney
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 3:46 am

WN732 wrote:
V-Tails can be temperamental. It was found that fuselages had to be extended longer than the conventional airplane design normally allowed. Otherwise they could be subject to "snaking." It was found that the advantage/disadvantage was moot and the added cost of design plus the possible need for a more fortified and longer structure would outweigh any weight and parts savings.

The Bonanza proved that it was doable but it did come with abundant cost. V Tailed Bonanzas were more susceptible to inflight overstress breakups than their conventional partners.



????? Extended longer than normally allowed????.......there are rules for what’s normally allowed...????.........NOT
Its your choice of words that makes it sound funny. A better way is saying it is Vtails have different design criteria which might not make it a suitable canidate for an airliner...

The V tail is just as strong as any other. The bonanza suffered from “improvements” to the orginal design....the “tail Mod” isn’t required for the first v tails. What happened after the first bonanza model 35 was Beechcraft kept adding area to the tail in front of the tail spar in the V35B/C/E and so forth..... It came to the point more fixed surface area was in front of the spar than behind. You can visually see the engineering and stress issues..Not an issue unless you pulled way to hard on the wheel... well, Beechcraft didn’t. To get the point, a V35B literally crashed in our backyard because the pilot overstressed it when he became “disoriented “ in the weather and pulled too hard.. i learned lots with the NTSB in our garage...

The V tail Bonanza is a GREAT plane and fly them all the time. I have flown the Fouga and do hiG maneuvers including loops, tailslides and racing. That tail isn’t coming off and it flies great on one engine.... well, even more underpowered but totally controllable...



If you want to know weak, the T-Tail is known for weakness...


Cheers..
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Rifitto
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 3:50 am

There is the Cirrus SF50 , a very light V-tail jet ,over 150 already in service with +400 still to deliver
https://www.youtube.com/watch?v=0rp6vFgviFs
 
SkyVoice
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 5:43 am

The Wikipedia article for the Beechcraft Bonanza states that Turner Airlines (which later became Lake Central) began service with three V-tail Bonanzas. Also, Central Airlines, which was headquartered in Ft. Worth and flew from 1949 to 1967, started off with eleven model A35 Bonanzas. So, the Beechcraft Bonanza Model 35 already served as your commercial aircraft with a V-tail. There are pics of Central Airlines Bonanzas on several websites.

https://en.wikipedia.org/wiki/Beechcraft_Bonanza#Civil
https://en.wikipedia.org/wiki/Central_Airlines#Fleet
"Blessed is he who can laugh at himself, for he shall never cease to be amused."
 
crobak
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 11:28 am

I’d guess that for the OEI case a v-tail will cause problems. Physically speaking with a v-tail you’ll always waste some chunk of energy through having the rudders also acting as elevators and vice versa. That’s offset by having to deal with less drag in straight and level flight but in case of one engine failing (on a conventional twin) you have will end up not only using the rudder for that but also constantly lose energy by unwanted elevator input that comes with it. That means losing energy by compensating unwanted pitching components while just trying to counter the yaw. Guess the required stronger (thus heavier) engines to counter that make it unworthy from an economical point of view
 
Reddevil556
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 12:57 pm

“Fork tailed doctor killer” I believe is the industry nickname for the Bonanza.
Jumped out of: C130H, C130J, C17A, C212, CH47, and UH60. Bucket list: C160, A400, C2
 
reltney
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 1:48 pm

crobak wrote:
I’d guess that for the OEI case a v-tail will cause problems. Physically speaking with a v-tail you’ll always waste some chunk of energy through having the rudders also acting as elevators and vice versa. That’s offset by having to deal with less drag in straight and level flight but in case of one engine failing (on a conventional twin) you have will end up not only using the rudder for that but also constantly lose energy by unwanted elevator input that comes with it. That means losing energy by compensating unwanted pitching components while just trying to counter the yaw. Guess the required stronger (thus heavier) engines to counter that make it unworthy from an economical point of view



I see your mind working and it’s great but it really is not as much as you think. When a twin looses an engine or asymmetric thrust , you have to displace the rudder which creates drag. On a V tail, you will see one ruddervator displaced way more than the other. In fact the opposite ruddervator hardly looks out of place but it is. I have rigged the controls on a V tail a few times. Foga and Bonanza. You get the same area drag from the flight control displacement. It is best described as induced drag. Is V tail induced drag greater than rudder only induced drag? You would need lab work and each plane is different. My bet is they are different but not to far at all from each other. It’s a great discussion.

This is a cool way to look at fin area for a V tail. Look at a Side profile view of the plane. Measure the area from that flat side view and multiply x2. That’s your vertical area. You want horizontal area? Look at a view from the top.

F-18 uses the ruddervator to aid in pitch control and ultimately rudder control. Northrop/McDonnell Douglas thought it was worth the drag.

Cheers
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OUTLAW KNIVES.

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keesje
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 2:38 pm

I saw some V tailed A310 sized windtunnel models long ago, but can't find pictures. Apparently it wasn't a very good idea.

Interestingly, it used to be faster, easier and cheaper to cut a wingtunnel model of e.g. such V tail, stick it to an existing fuselage and get decent feedback on what happens under different angles, speeds, etc., then doing extensive CFD modelling and verification / in-fighting on results by a lot of expensive guys. It think that's still the case. :biggrin:

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CALTECH
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 4:07 pm

Future of V ?

Image

Image

Close to a V
Image

Image

Image

Image

Image

Image

Image

Image
You are here.
 
crobak
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Re: Why no commercial aircraft with V-tail ?

Fri Nov 01, 2019 6:05 pm

reltney wrote:

I see your mind working and it’s great but it really is not as much as you think. When a twin looses an engine or asymmetric thrust , you have to displace the rudder which creates drag. On a V tail, you will see one ruddervator displaced way more than the other. In fact the opposite ruddervator hardly looks out of place but it is. I have rigged the controls on a V tail a few times. Foga and Bonanza. You get the same area drag from the flight control displacement. It is best described as induced drag. Is V tail induced drag greater than rudder only induced drag? You would need lab work and each plane is different. My bet is they are different but not to far at all from each other. It’s a great discussion.

This is a cool way to look at fin area for a V tail. Look at a Side profile view of the plane. Measure the area from that flat side view and multiply x2. That’s your vertical area. You want horizontal area? Look at a view from the top.

F-18 uses the ruddervator to aid in pitch control and ultimately rudder control. Northrop/McDonnell Douglas thought it was worth the drag.

Cheers




Thank you for using such kind words to tell me that from your point of view I’m wrong. That’s how forum discussions should be like! :)
Anyway - let me elaborate a little on what I meant. Maybe I’m still wrong but from an engineering point of view I don’t think i actually am:

You’ll have an engine failure in a conventional twin. To keep straight and level flight you’ll need to apply a certain amount of rudder to counter the induced yaw. We do that by applying a force F=moment•arm. The arm is a given since we can’t change the location of the fin so we’ll have to take care of the yawing moment we’ll need to create.

Ideally our moment acts along the longitudinal axis (around the yawing axis if you want) only. On a conventional tail we achieve that by only using the rudder because it’s not angled but parallel to the yawing axis (more or less. It induces some unwanted forces because it is placed higher than the center of gravity but that’s another story).

Now you take the same plane and throw a v-tail on it. Let’s assume it will have a fin spread of 90 degrees (so 45 deg each off the yaw axis). You need the same force F=m•a to be induced. You haven’t changed „a“ since the AC is the same. To induce the same moment as the conventional tail you’ll have to have a surface thrown into the airstream which is 1/cos(45) = 1.4 times the surface needed when you have a conventional rudder acting in pure parallel to the yawing axis.

If that is sufficient to disregard the design? I have no clue ;) The fact that the F-18 uses its angled fins to aid in pitch control actually supports my thesis that angled fins in all flight regimes induce significant (sometimes wanted, sometimes unwanted but for sure efficiency degrading) side effects.

Cheers

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