DeskPilot
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Canoes On The Convair CV-990

Thu Sep 02, 2004 12:40 pm

I assume that the canoes located on top of the wing hid/streamlined the flap extension mechanism. Correct ?


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Photo © Bob Garrard



Anyone know why Convair chose to place this on top of the wing ? Was this a benefit to the "ramp rats" in that there was less items to hit your head on under the wing ?

Are there any other types that used this approach ?
By the way, is there anyone on board who knows how to fly a plane?
 
L-188
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 12:42 pm

The Germans did a lot of work on those surfaces during WWII, I want to say they called the Kurchmann Carrots but don't hold me to that.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
OPNLguy
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 12:58 pm

That aircraft was slightly before my time, but I seem to recall reading somewhere that the 990 was so fast, they had to put these things on the winds to dissipate the shock waves, or for some other related aerodynamic purpose. (Someone correct me if my recollection is faulty). I believe they also held fuel...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
DeskPilot
Topic Author
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 1:02 pm

Some history of its demise. Note the lack of range ("..was unable to fly across the USA with a full payload..")

"...The CV-990, originaly developed as the CV660 but re-numbered
for sales promotion purposes, was flewn for the first time on
January 1961, the intercontinental version being known as the
Coronado.

Continual development problems delayed deliveries. Trials revealed
the need for modifications, including the addition of Krueger-
type flaps on the leading edge between the fuselage and inner pylons
to increase elevator effectiveness. The outer pylons were shortened
by moving the engines back some 720 mm (29 in.), to eradicate excessive
vibration, but when flight trail were resumed on April 20, 1961,
serious drag manifest itself, and it was discovered that the CV990
was unable to meet its speed 990 km/h (620 m.p.h.) maximum crusing and
range guarantees, and was unable to fly across the USA with a full payload.

The CV-990 differs from the CV-880 in having a longer fuselage, greater
wing chord and area, more fuel and anti-shock bodies on the wing
trailing edge.

The Convair CV-990 was ordered by Swissair, Scandinavian Airlines
System SAS, Real Aerovias/Varig and American Airlines. Several
air-carriers had both the CV-880 and CV-990 in their fleets but due
to ecconomical reasons they were later faded.

Spantax SA, a Spanish Charter Company became a major operator of the
Convair CV990A Coronado...."


By the way, is there anyone on board who knows how to fly a plane?
 
lorm
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 1:10 pm

These bumps or canoes were also known as Whitcomb bumps ,which reduced the intensity and drag of shockwaves.
Brick Windows
 
OPNLguy
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 1:12 pm

ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
JetMechMD80
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 7:00 pm

They were called anti-shock bodies, and they also held fuel in them.
"I get along great with nobody"~ Billy Idol
 
lorm
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 7:18 pm

I am really not sure where the Whitcomb designation fits in, (designer?) but yes the 990 was tested up to mach .98

NM.... http://www.fact-index.com/w/wh/whitcomb_area_rule.html

Yes lazy, ready to sleep! Eat your heart out, all you need to know on Whitcomb bumps.

[Edited 2004-09-02 12:34:24]
Brick Windows
 
FBU 4EVER!
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 7:57 pm

These "Küchemann Carrots" were a 1950's solution to high speed/compressibility problems and they first appeared on the British Handley Page Victor bomber.
The Soviets also designed bombers with this feature.In these cases the carrots also functioned as wheel wells.
"Luck and superstition wins all the time"!
 
QantasA332
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RE: Canoes On The Convair CV-990

Thu Sep 02, 2004 8:03 pm

(Richard) Whitcomb was a NASA/NACA engineer who did a lot of work in many different areas of aerodynamics and aircraft design. Some of his most well-known contributions to modern aircraft design are the winglet and the aforementioned area rule -related developments, to name just two. He was quite an excellent engineer...

Cheers,
QantasA332
 
broke
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RE: Canoes On The Convair CV-990

Fri Sep 03, 2004 10:18 pm

The fairings on the trailing edge of the 990's wing are called Whitcomb Shock Bodies. They are intended improve the transonic drag of the airplane and are a form of area rule. As a note, the Shock Bodies on the 990 predate those on the Victor, as they were added to the Victor after production of the airplane was finished.
The Victor is the only airplane that I know off that employs a crescent wing shape. If you look are the wing from above, you would see that the wing sweep decreases as you go further out on the wing. A compromise to get a higher critical Mach number and have reasonable approach and take off speeds.
 
Mr Spaceman
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RE: Canoes On The Convair CV-990

Sat Sep 04, 2004 3:14 am

Hi guys.

Here's a photo that shows a red fuel cap (I guess that's what it is Big grin) on one of the Convair CV-990-30-6's Whitcomb Shock Bodies.


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Photo © Charles Falk



Here's a nice aerial view of a Coronado .....


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Photo © Markus Herzig



Here's a Convair 990-30-5.


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Photo © Johan Ljungdahl



Here's the Handley Page Victor K.2 with it's anti-shock bodies visible.


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Photo © Simon Thomas
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Photo © Tom Everitt



Regarding fuel, I always liked the "Slipper Tanks" on the De Havilland DH-106 Comet 4C. They make the jet airliner look FAST!


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Photo © Eduard Marmet




Chris  Smile
"Just a minute while I re-invent myself"
 
ba97
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RE: Canoes On The Convair CV-990

Sun Sep 05, 2004 11:24 am

Are the slipper tanks basically extra wing fuel tanks? If so, I throw a question out- How come other planes do not do it for greater range? I suspect storing fuel inside is easier than outside on a wing and having a ground crew trained to put on/take off tanks is expensive...did I just answer my question?
there is economy class, business class, first class...then Concorde..pure class
 
prebennorholm
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RE: Canoes On The Convair CV-990

Thu Sep 09, 2004 7:17 am

Ba97, the DH-106 went through a tremendous development as more powerful engines became available. While the Comet 1 could hardly match the performance of a small RJ today, then the Comot 4 became a much heavier and much more capable plane.

Still the wing didn't change all that much. Fuel capacity became a limiting factor. Most dramatic wing change was a substantially changed leading edge profile to improve take-off performance - introduced on the Comet 3 if I remember correctly.

In order to just be able to cross the pond with reduced payload a minimum change Comet 4C version was produced with those slipper tanks.

The Comet 4C would have been a better plane without those slipper tanks. But that would have cost a lot of money and time for redesigning the wing. That could have been feasible if the Comet at that time - the late fifties - had been looking into a bright future. But more modern designs were already being tested or were well advanced on the drawing board.

And about the Whitcomb bodies: Already in the 70'es the airline companies discovered that they don't sell Mach numbers to their passengers. They sell travel at competitive prices.

That effectively ended the "speed rush". Speed settled down at M=0.80 to 0.84, and slightly slower on short haul.

That is more obvious today than even before as the airlines let the passengers stand for hours in check-in queues to be able to save two bucks on handling costs (especially the LCCs). And get away with it.
Always keep your number of landings equal to your number of take-offs
 
SlamClick
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RE: Canoes On The Convair CV-990

Thu Sep 09, 2004 11:17 am

Bear something in mind guys. It is my observation that life in the jet routes moved at about M .76 in the 1980's and at about M .80 now. So if you build a plane that will fly at point nine eight it will just get stuck in traffic.

Add to this, my company blocks flights at about ten minutes longer than it actually takes to fly them on a good day. What is the point of going faster?

I have a really nice fast sports car and I feel that I personally own the mountain roads between here and the ocean. It is true until I come up behind a motor home or a Volvo. Same principle for fast airplanes. Okay if there are only a few. Not good when there are more than a few, but not enough to raise the bar.

BTW Why do they bother putting rearview mirrors on Volvos?
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
aloges
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RE: Canoes On The Convair CV-990

Sun Sep 12, 2004 5:03 am

Thanks for the replies, folks! I read through them, and they're much appreciated - you learn a thing or two on this website every day! Big grin

"BTW Why do they bother putting rearview mirrors on Volvos?"

So the driver can see the poor mad guy crawling behind him and laugh his you-know-what off?  Big grin
Don't cry because it's over, smile because it happened.

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