Tg 747-300
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Ventral And Dorsal Fins.

Tue Jul 25, 2006 10:26 am

Hi,

Just been reading about aircraft stability, and the reasons for using dorsal and ventral fins. They are installed to increase directional stability at high sideslip angles.
That makes me wondering. What desides if you instal only a dorsal, only ventral or both.

AFIK most commercial airliners uses the dorsal fin only, while some smaller jets like the Lear-jet etc. also uses the ventral fin.

Is the ventral fin installed when the regular fin and dorsal fin is not enough to produce the required stability? Is there airplanes with ventral fins but without dorsal fins?

Also, the 731,732 does not have a dorsal fin, but all other 737's do. Why is that. Did the original 737 have some other stabilizing means that couldn't be carried over to the classics and NG's?

tg 747-300
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Starlionblue
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 11:14 am

Quoting Tg 747-300 (Thread starter):
What desides if you instal only a dorsal, only ventral or both.

On the A-4, they added ventral fins after a few pilots took a swim. The plane was unstable after cat shots and tended to yaw violently.

Quoting Tg 747-300 (Thread starter):
Is there airplanes with ventral fins but without dorsal fins?

Not as far as I know, but I'm sure someone has built one. There's more space upwards. Downwards you have to think of ground clearance.

Quoting Tg 747-300 (Thread starter):
Also, the 731,732 does not have a dorsal fin, but all other 737's do.

Sure they do. The big thing at the end with the rudder attached to it.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Tg 747-300
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 11:54 am

Quoting Starlionblue (Reply 1):
Also, the 731,732 does not have a dorsal fin, but all other 737's do.

Sure they do. The big thing at the end with the rudder attached to it

737-200 tail

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737-300 tail

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To me it looks like the 737-300 has some kind of a dorsal fin while the -200 don't. or is it just that the -300 has a biger or more noticable dorsal fin with a more "square" look. ?

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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 1:00 pm

Not to be pedantic, but I'm curious what differentiates between a dorsal fin and a vertical stabilizer? Is it the rudder? If a dorsal fin had a rudder, would it be called a vstab instead?

A ventral fin is easy to see and define. But what makes a dorsal fin a fin? If a plane (like the A-4) always had a "leading edge extension" on the vstab, was it called a dorsal fin? Or does the name only apply to add-ons after the fact, like on the 737?

Quoting Starlionblue (Reply 1):
On the A-4, they added ventral fins after a few pilots took a swim.

Did you mean A-4? As in Skyhawk? I never seen an A-4 that had a ventral fin. The only USN planes with ventral fins that I can think of (off the top of my head) would be the F-8 and the F-14.
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aeroweanie
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 1:19 pm

Dorsal fins are typically added to prevent "rudder lock". Rudder lock is a decrease in the rudder hinge moment that can happen at large yaw angles. This was first brought to light by the crash of a Boeing 307 on a demo flight on March 18, 1939. The aircraft had one engine shut down to demonstrate engine-out characteristics. Full rudder was applied to counter the yawing moment. The rudder locked over at full deflection and couldn't be centered. This caused the airplane to go into spin and crash.

Ventral fins are added for added directional stability and/or to reduce the drag of an upswept rear fuselage. Dual ventral fins were added to these Hawkers to counteract the destabilizing effect of the forward canoe:


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Photo © Mark Abbott
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Photo © AirNikon



A single ventral fin was added to this GIIB to counteract the destabilizing effect of the dorsal pod:


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Photo © Jarrod Wilkening
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Photo © Ralph Duenas - Airplanespotters



The use of ventral fins to reduce the drag due to fuselage upsweep was pioneered on the Short Belfast:


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Photo © Jorgos Tsambikakis / Travel-Images
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Photo © David Townsend - WorldAirImages



The ventral fins were added by BLR to the Beech Duke to reduce drag due to the fuselage upsweep:


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Photo © Derek Ferguson
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Photo © Vladimir Kostritsa



Raisbeck offers a dual aft body strake kit for the Beech King Air. This both improves directional stability and reduces drag. It is required on King Airs that carry the CATPASS pod, due to its destabilizing effect (second picture):


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Photo © Colin Hines
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Photo © Richard Austen



"Beagle Ears" were used on the Sikorsky H-53 to reduce the drag of the upswept rear fuselage:


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Photo © Gary Stedman
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Photo © Peter Unmuth-VAP



The ventral fins on Learjet 31s, 45s, 55s and 60s were added to cause a nose down pitching moment at stall:


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Photo © Harri Koskinen
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Photo © Piotr Biskupski

 
DH106
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 2:53 pm

Ventral fins are also sometimes added to improve spin recovery characteristics where the tailplane may 'mask' the fin and rudder with upwards moving air from the tailplane, reducing the efficiency of the fin/rudder. The ventral position is below the tailplane and thus in this scenario is in 'clean' air.
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 8:43 pm

Quoting Tg 747-300 (Reply 2):
To me it looks like the 737-300 has some kind of a dorsal fin while the -200 don't. or is it just that the -300 has a biger or more noticable dorsal fin with a more "square" look. ?

The thing you show in the pic is a fin, AKA vertical stabilizer. The little extension at the front of the 733 fin simply extends the shape.

Quoting Tg 747-300 (Reply 2):

Quoting Starlionblue (Reply 1):
On the A-4, they added ventral fins after a few pilots took a swim.

Did you mean A-4? As in Skyhawk? I never seen an A-4 that had a ventral fin. The only USN planes with ventral fins that I can think of (off the top of my head) would be the F-8 and the F-14.

Brainfart. I meant the F-8 Crusader.
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Tg 747-300
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 9:13 pm

Quoting Starlionblue (Reply 6):
The thing you show in the pic is a fin, AKA vertical stabilizer. The little extension at the front of the 733 fin simply extends the shape.

That was suprising, always been under the impression that the extension on the -300 was a dorsal fin.

Then could somebody please point out in a picture what a dorsal fin looks like?

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Starlionblue
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 9:26 pm

Quoting Tg 747-300 (Reply 7):
Quoting Starlionblue (Reply 6):
The thing you show in the pic is a fin, AKA vertical stabilizer. The little extension at the front of the 733 fin simply extends the shape.

That was suprising, always been under the impression that the extension on the -300 was a dorsal fin.

Then could somebody please point out in a picture what a dorsal fin looks like?

Oh dear. "Dorsal" means "on the back". So any fin on the top of the plane is a dorsal fin.

The thing you are referring to (front extension to the fin) is part of the dorsal fin (AKA vertical stabilizer) and has to do with stability. My guess is that since the 737Classics have more powerful engines than the 737Jurassics they need more lateral stability for engine out situations. Thus the enlarged fin.
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Tg 747-300
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 9:38 pm

Quoting Starlionblue (Reply 8):
Oh dear. "Dorsal" means "on the back". So any fin on the top of the plane is a dorsal fin

Seems like I've learning something new all the time (which is great  Silly)

I looked up in my JAA "Principles of Flight". They describe and highlight the dorsal fin as an area similar to what i was refering to on the -300. So I guess thats where I got my ideea from. "The dorsal fin is located in front of the main fin, while the ventral is located below."

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Jetlagged
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 10:04 pm

The 737 Classic has increased side area ahead of the aerodynamic centre due to the CFM56 engines, hence the need to increase the fin area for directional stability. The 737 Classic had a slightly longer tail arm than the 737 Original, which also helps directional stability.

Directional control in the event of an engine failure comes primarily from the rudder, although the increased fin area will help too.

The 737 type of fin extension used to be known as a fin fillet in the good old days.

Sometimes ventral fins are added at the insistence of the certifying authority, as happened in the case of the 707 and the UK CAA, as I recall.

I had wondered about those Learjet fins. Nice to know the reason they are fitted.
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 11:29 pm

Quoting Tg 747-300 (Reply 9):
I looked up in my JAA "Principles of Flight". They describe and highlight the dorsal fin as an area similar to what i was refering to on the -300. So I guess thats where I got my ideea from. "The dorsal fin is located in front of the main fin, while the ventral is located below."

I see the confusion. The JAA's definition of fin is pretty arbitrary, not to mention flawed, in my humble opinion. But who am I to argue?  Wink
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474218
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RE: Ventral And Dorsal Fins.

Tue Jul 25, 2006 11:46 pm

Quoting Starlionblue (Reply 8):
Oh dear. "Dorsal" means "on the back". So any fin on the top of the plane is a dorsal fin.

The actual name for fin on top of and aircraft is the "VERTICAL STABILIZER". A dorsal fin can be described as a fairing that extends the vertical stabilizer further forward on the fuselage. A couple of reasons for adding a dorsal fin could be added to increase stability or reduce buffeting. The following site shows a dorsal fin added to a Piper Cherokee, just forward of the vertical stabilizer.
http://www.planetools.com/NEWIACdorsalfin.htm
 
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 12:25 am

Quoting 474218 (Reply 12):
Quoting Starlionblue (Reply 8):
Oh dear. "Dorsal" means "on the back". So any fin on the top of the plane is a dorsal fin.

The actual name for fin on top of and aircraft is the "VERTICAL STABILIZER". A dorsal fin can be described as a fairing that extends the vertical stabilizer further forward on the fuselage. A couple of reasons for adding a dorsal fin could be added to increase stability or reduce buffeting. The following site shows a dorsal fin added to a Piper Cherokee, just forward of the vertical stabilizer.
http://www.planetools.com/NEWIACdors...n.htm

It's all semantics. Plenty of sources call the vertical stabilizer "fin".

But I would agree that many manufacturers will call it "dorsal fin". That's fine, as long as everyone is clear on what we are talking about. Which obviously is not the case.  Wink
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HAWK21M
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 12:43 am

Quoting Tg 747-300 (Thread starter):
Also, the 731,732 does not have a dorsal fin, but all other 737's do.

The B731/2 too have a Dorsal Fin,Except its not long as the Later versions.
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 12:44 am

Quoting 474218 (Reply 12):
The actual name for fin on top of and aircraft is the "VERTICAL STABILIZER"

Only if you are an American.  Smile In the UK, for example, it's traditionally known simply as the fin. All other types of fin need some qualifying adjective, like ventral.

We also still have things called tailplanes too. None of this horizontal stabiliser nonsense.  Wink

Not sure when this style of redundant verbage started, but I'd guess NASA had something to do with it. EVA for a "space-walk" is bad enough, until you remember it stands for "extra-vehicular activity".

Anyway, if you want to use these long words for precision, it should really be a directional stabiliser, not a vertical stabiliser.
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 12:55 am

Quoting Tg 747-300 (Reply 2):
To me it looks like the 737-300 has some kind of a dorsal fin while the -200 don't. or is it just that the -300 has a biger or more noticable dorsal fin with a more "square" look. ?

It may be semantics, but you are correct. The extension to the 737-300/-400/-500 vertical stabilizer is a dorsal fin.

The 707-100 did have a ventral fin; was not required on the -300.
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 1:01 am

Quoting Jetlagged (Reply 15):
Anyway, if you want to use these long words for precision, it should really be a directional stabiliser, not a vertical stabiliser.

Isn't the horizontal one also directional?  yes 
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DH106
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 1:40 am

Quoting Miamiair (Reply 16):
The 707-100 did have a ventral fin; was not required on the -300.

All -400 series (Conway powered) have a the larger sized ventral fin, and -100/720 aircraft have a smaller fin. I think some -300s do have the smaller fin also. Perhaps it was fitted if the certifying authority of the country of the original buyer required it.
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 7:35 am

Quoting DH106 (Reply 18):
All -400 series (Conway powered) have a the larger sized ventral fin, and -100/720 aircraft have a smaller fin. I think some -300s do have the smaller fin also. Perhaps it was fitted if the certifying authority of the country of the original buyer required it.

Having said the above, all the series '-300s' I can find pictures of on A.Net with a ventral fin seem to be -400 series masquerading as -300's

Serial nos: 17607,17608,17626,17682,17930,18084 - they're all labelled as -3xx series, but clearly have the -400 type trailing nose gear door, what look like Conway engines and the said ventral fin. What say our experts?
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 4:31 pm

Quoting Jetlagged (Reply 15):
Only if you are an American

Out here its Reffered to as the Vertical Stablizer too.What caused the B737-300 & Beyond to add a Longer Dorsal fin.

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Buyantukhaa
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 8:21 pm

More ventral fins:


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Photo © Ian Older



At the second one you can clearly see at what (maximum) pitch angle it could take off.

King of ventral fins must be the Super Crusader though:



How on earth did that work??? It may have been able to take off only from carriers, or did they fold up?
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vzlet
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RE: Ventral And Dorsal Fins.

Wed Jul 26, 2006 8:42 pm

Quoting BuyantUkhaa (Reply 21):
or did they fold up?

They folded, and looked like a second pair of horizontal stabilizers.

Another plane with a folding ventral fin is the Flogger:

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texfly101
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RE: Ventral And Dorsal Fins.

Thu Jul 27, 2006 6:21 am

Probably one of the most interesting of the dorsal and ventral control surface investigations, particularly at high angles of attack and high mach, where the effects become very apparent as to directional control and stability, is the 1950's NASA X-15 research project. The aircraft had a removable ventral fin that was investigated for on and off, and measured control stability transients in its regime of flight. For anyone who is interested, Jay Miller's book, "The X-Planes" (Aerofax) is a good read regarding this as is Jenkins "Hypersonic! The Story of the North American X-15".
Just to add in other examples of ventral fins, look at the F-16, F-104, and B707. usually, any airplane that has rudder blanking at high AOA will have a ventral fin for added stability. Add in fuselage area or stores area ahead of the COP and you usually need added longitudinal control surfaces behind the COP. A lot of times, this area is designed in the beginning as every designer knows how airplanes get bigger with time.
 
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RE: Ventral And Dorsal Fins.

Thu Jul 27, 2006 8:13 am

Quoting Texfly101 (Reply 23):
usually, any airplane that has rudder blanking at high AOA will have a ventral fin for added stability.

Chuck Yeager would have had an easier time if rudder blanking had been better known in 1974.  Wink
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RE: Ventral And Dorsal Fins.

Thu Jul 27, 2006 11:24 am

Quoting Tg 747-300 (Reply 7):
Then could somebody please point out in a picture what a dorsal fin looks like?

The words 'dorsal' and 'ventral' come from aquatic animals, dorsal fins on top and ventrals below. Sharks, fish, whales, etc all have them. No, when the plane flips over the parts don't change their names.  Smile

Not just on fuselages, certain hypersonic vehicle have them elsewhere like X-43 have them integrated together, dorsal and ventral and rudder all-in-one (white section in the back):

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RE: Ventral And Dorsal Fins.

Thu Jul 27, 2006 1:21 pm

Quoting Starlionblue (Reply 24):
Chuck Yeager would have had an easier time if rudder blanking had been better known in 1974

I think you might be referring to his flight in 1963 in the NF-104. That flight was in a specially configured, rocket assisted F-104 that was set up to enter the flight regime where aerodynamic controls are not possible at over 100,000 ft. So it used reactive jets to control attitude. He went too far over the top in a higher than called for AOA and then ended up in an unrecoverable upside down flat spin where he ejected from the aircraft. While the F-104 has suffered from its share of stability concerns, just ask the Germans, that accident was actually due to a departure from the planned flight path. No dorsal fin, which the F-104 has, is effective at 100,000+ ft...in 1974, he was 1 year from retiring...or at least thats what he tells me.. Smile (just being a know it all wiseass)
 
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RE: Ventral And Dorsal Fins.

Thu Jul 27, 2006 9:15 pm

Quoting Starlionblue (Reply 24):
Quoting Texfly101 (Reply 23):
usually, any airplane that has rudder blanking at high AOA will have a ventral fin for added stability.

Chuck Yeager would have had an easier time if rudder blanking had been better known in 1974.

Of course I meant 1947. Oops. Texfly101, I am referring to the X-1. They had to trim the tailplane since the elevator was completely blanked at high speeds.
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Jetlagged
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RE: Ventral And Dorsal Fins.

Sun Jul 30, 2006 6:27 am

Quoting Starlionblue (Reply 17):
Isn't the horizontal one also directional?

Strictly speaking it should be the longitudinal stabiliser. As in longitudinal and directional stability. I still prefer tailplane.

Quoting HAWK21M (Reply 20):
Out here its Reffered to as the Vertical Stablizer too.

Only because your Boeing aircraft manuals are written in American  Smile
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BoeingOnFinal
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RE: Ventral And Dorsal Fins.

Tue Aug 01, 2006 10:14 pm

Described above, ventral fins are added to reduse drag of a non sweep fuselage.

What is the difference between a sweep (swept?) and non sweep fuselage?
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RE: Ventral And Dorsal Fins.

Tue Aug 01, 2006 11:43 pm

Quoting Jetlagged (Reply 28):
Only because your Boeing aircraft manuals are written in American

What Makes you think I was talking BOEING.  biggrin 
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IFIXCF6
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RE: Ventral And Dorsal Fins.

Wed Aug 02, 2006 10:12 am

You people would have fun with "cockpit" vs. "flightdeck"  stirthepot 

Quote:
Only because your Boeing aircraft manuals are written in American

I'm reminded of a book of engineering that a friend found at a garage sale. It was written in or about 1922, it is British, and refers to the aircraft "vessel" and "turning flaps". It has a note: "The use of foreign terms, such as fuselage and aileron in the English language cannot be too strongly condemed."
I got a laugh from that!
 
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HAWK21M
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RE: Ventral And Dorsal Fins.

Wed Aug 02, 2006 1:15 pm

Quoting IFIXCF6 (Reply 31):
You people would have fun with "cockpit" vs. "flightdeck"

And to add "Control Cabin"  Smile
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Jetlagged
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 12:33 am

Quoting IFIXCF6 (Reply 31):
I'm reminded of a book of engineering that a friend found at a garage sale. It was written in or about 1922, it is British, and refers to the aircraft "vessel" and "turning flaps". It has a note: "The use of foreign terms, such as fuselage and aileron in the English language cannot be too strongly condemed."
I got a laugh from that!

Me too, but that's an odd ball as French terms like aileron and longeron must have been pretty well established by 1922. "Vessel" sounds quaint, but Americans often refer to aircraft, especially military, as ships. As in "two ship formation".

Actually it's the French who are most notoriously defensive of corruption of their language. Aviation French is no exception. I was amazed to find that the French for elevator is gouverne de profondeur, which literally translates as depth control!

I was only commenting on the replacement of established aviation terms (e.g. tailplane) with more verbose new ones (horizontal stabiliser). That's eight syllables instead of two  Smile

Quoting IFIXCF6 (Reply 31):
You people would have fun with "cockpit" vs. "flightdeck"

Not really, because a flightdeck is used for a multi-crew side-by-side control position, whereas cockpit usually refers to a small single seat control position. Maybe on the A380 it should be called "The Bridge". Big grin
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Areopagus
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 3:05 am

Quoting Tg 747-300 (Thread starter):
Is there airplanes with ventral fins but without dorsal fins?

The first prototype XP-56 Black Bullet, depending on what you make of the dorsal spine. http://www.wpafb.af.mil/museum/research/p56.htm

Quoting Lehpron (Reply 25):
The words 'dorsal' and 'ventral' come from aquatic animals, dorsal fins on top and ventrals below. Sharks, fish, whales, etc all have them.

Exactly so. I don't think ichthyologists would let you get away with calling a slight extension of the caudal fin a "dorsal fin". (Indeed, they would frown on calling the caudal fin a dorsal fin.) I think it is an abuse of language to call a fillet a fin, when it's just an enlargement of an existing fin.
 
OldAeroGuy
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 3:21 am

Quoting DH106 (Reply 18):
All -400 series (Conway powered) have a the larger sized ventral fin, and -100/720 aircraft have a smaller fin. I think some -300s do have the smaller fin also. Perhaps it was fitted if the certifying authority of the country of the original buyer required it.



Quoting DH106 (Reply 19):
Having said the above, all the series '-300s' I can find pictures of on A.Net with a ventral fin seem to be -400 series masquerading as -300's

Serial nos: 17607,17608,17626,17682,17930,18084 - they're all labelled as -3xx series, but clearly have the -400 type trailing nose gear door, what look like Conway engines and the said ventral fin. What say our experts?

The 707 series ventral fins were there as ground over-rotation protectors to prevent the type of takeoff rotation stall that caused a Comet accident. They were not added to increase directional stability.
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Jetlagged
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 4:31 am

Quoting OldAeroGuy (Reply 35):
The 707 series ventral fins were there as ground over-rotation protectors to prevent the type of takeoff rotation stall that caused a Comet accident. They were not added to increase directional stability.

That may be true, but you can be sure that the ventral fin area was part of the directional stability calculations.

[Edited 2006-08-02 21:35:08]
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OldAeroGuy
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 6:58 am

Quoting Jetlagged (Reply 36):
That may be true, but you can be sure that the ventral fin area was part of the directional stability calculations.

You have to determine what the directional stability is based on the airplane configuration, but the ventral fin was not required for the 707's to have a certified level of directional stability.
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DH106
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 7:08 am

Quoting OldAeroGuy (Reply 35):
The 707 series ventral fins were there as ground over-rotation protectors to prevent the type of takeoff rotation stall that caused a Comet accident. They were not added to increase directional stability.

So - are you saying that the fin was required for British certification?
If so - why don't the -300's on the British register have them?
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OldAeroGuy
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RE: Ventral And Dorsal Fins.

Thu Aug 03, 2006 11:53 pm

Quoting DH106 (Reply 38):
So - are you saying that the fin was required for British certification?

No, a safe airplane has no national boundaries. Minimum unstick speed is a requirement for all Cert agencies.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
DH106
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RE: Ventral And Dorsal Fins.

Fri Aug 04, 2006 1:43 am

Quoting OldAeroGuy (Reply 39):
No, a safe airplane has no national boundaries. Minimum unstick speed is a requirement for all Cert agencies.

Granted, and nice cliché - but why then wasn't the fin fitted to ALL 707's?
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HAWK21M
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RE: Ventral And Dorsal Fins.

Fri Aug 04, 2006 4:44 pm

Quoting Jetlagged (Reply 33):
Not really, because a flightdeck is used for a multi-crew side-by-side control position, whereas cockpit usually refers to a small single seat control position. Maybe on the A380 it should be called "The Bridge".


Whats the Seating Capacity of the A380 to warrant that name.
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Jetlagged
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RE: Ventral And Dorsal Fins.

Fri Aug 04, 2006 10:11 pm

It's called "the bridge" on a ship regardless of the ship's size, so long as the structure spans the ship (hence the name of course). If not it's usually called a wheelhouse. The A380 will carry more pax than many ships, but wheelhouse doesn't sound quite so good, and it is full width (of the nose at least).  Smile
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lehpron
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RE: Ventral And Dorsal Fins.

Sun Aug 06, 2006 2:56 am

Quoting OldAeroGuy (Reply 39):
No, a safe airplane has no national boundaries

Which is why we see many russian airliners for domestic flights within the USA.  Smile
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Starlionblue
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RE: Ventral And Dorsal Fins.

Sun Aug 06, 2006 4:21 am

Quoting Lehpron (Reply 43):
Quoting OldAeroGuy (Reply 39):
No, a safe airplane has no national boundaries

Which is why we see many russian airliners for domestic flights within the USA.

Good one. Still, it is more a perception and operational cost issue than a safety issue.
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ptrjong
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RE: Ventral And Dorsal Fins.

Sun Aug 06, 2006 5:56 am

Quoting Jetlagged (Reply 15):
Only if you are an American. In the UK, for example, it's traditionally known simply as the fin. All other types of fin need some qualifying adjective, like ventral.

We also still have things called tailplanes too. None of this horizontal stabiliser nonsense.

Not sure when this style of redundant verbage started, but I'd guess NASA had something to do with it. EVA for a "space-walk" is bad enough, until you remember it stands for "extra-vehicular activity".

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chimborazo
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RE: Ventral And Dorsal Fins.

Mon Sep 03, 2012 2:23 pm

Quoting Starlionblue (Reply 13):
Quoting 474218 (Reply 12):
Quoting Starlionblue (Reply 8):
Oh dear. "Dorsal" means "on the back". So any fin on the top of the plane is a dorsal fin.

The actual name for fin on top of and aircraft is the "VERTICAL STABILIZER". A dorsal fin can be described as a fairing that extends the vertical stabilizer further forward on the fuselage. A couple of reasons for adding a dorsal fin could be added to increase stability or reduce buffeting. The following site shows a dorsal fin added to a Piper Cherokee, just forward of the vertical stabilizer.
http://www.planetools.com/NEWIACdors...n.htm

It's all semantics. Plenty of sources call the vertical stabilizer "fin".

Yep.

In the "Building the Biggest" doc on the A-380 the uber-camp guy (who is prettly funny) in charge of the the big thing sticking out of the top of the arse-end of the plane is the VTP engineer. Vertical Tail Plane. He also uses the word "fin" when describing it. Is he- and therefore Airbus- using wrong terminology because he doesn't call it by the "actual" (Boeing?) description?  

There can be more than one name for the same thing and they can all be correct...

As someone else suggested, the vertical stabiliser suggests a part designed to stabilise in the vertical plane, ie what the horizontal tailplane actually does. In that sense it would perhaps be better to call it "stabiliser that is vertical" or something. Or "lateral stabiliser" if you want to describe what it actually does.

But we don't need to because we know that a fin, a vertical tail plane, a vertical stabiliser etc are all the same thing!  
 
Viscount724
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RE: Ventral And Dorsal Fins.

Mon Sep 03, 2012 9:36 pm

In case others haven't noticed, Reply 46 reactivated a 6-year-old thread.

Just a suggestion, but when a years-old thread is reactivated, it would be helpful to mention that. Might avoid someone replying to a thread that he/she may have already replied to when the subject was first discussed, but may have forgotten.

How do people even find 6-year-old threads?  
 
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Jetlagged
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RE: Ventral And Dorsal Fins.

Tue Sep 04, 2012 4:43 pm

Quoting Viscount724 (Reply 47):
How do people even find 6-year-old threads?

The weird and wonderful A.net search function. It doesn't sort the posts it finds by date so you can easily dig up a very old thread and reply to it without realising just how old it is. A caution message that you've opened a very old thread might help.

If it's an old thread you've contributed to, like this one for me, it's a nostalgic trip down memory lane.
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LH707330
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RE: Ventral And Dorsal Fins.

Wed Sep 05, 2012 4:34 am

Quoting DH106 (Reply 19):

Serial nos: 17607,17608,17626,17682,17930,18084 - they're all labelled as -3xx series, but clearly have the -400 type trailing nose gear door, what look like Conway engines and the said ventral fin. What say our experts?

The -300 and the -400 are pretty much identical except for the engines. The trailing door was changed sometime in 1963/4 IIRC for all models. Most of the earlier -300 and -400 have the spade door while a lot of the -300B have the new one. Read this article for a more detailed description.

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