Vought F7U Cutlass

[KJ_Lesnick]

Something I don't understand about the F7U is this: The design (either the XF7U-1 or F7U-1) ended up considerably lighter than the variants that entered carrier service

Yet the wing area was the same and the nose-gear was jacked up that high.  Admittedly, I could sort of understand the big wing as it would have been able to fly even higher and would have probably been able to land even slower.  

Still, the nose-gear makes little sense to me as the plane at a lighter weight would have a lower takeoff and landing speed

[rickshaw]

The nose gear was required to increase the incidence of the wing for take off.  It was also done on the F-4 Phantom.  The higher the incidence the better the airflow at low speeds and hence greater lift.  The F-8 Crusader did the same thing but with a variable incidence wing.

[KJ_Lesnick]

The nose gear was required to increase the incidence of the wing for take off.

It needed it even when the weight was down to 16,000 or 18,000 pounds?  Sure it makes sense when the weight increased to 24,000 pounds...

[rickshaw]

The nose gear was required to increase the incidence of the wing for take off.

It needed it even when the weight was down to 16,000 or 18,000 pounds?  Sure it makes sense when the weight increased to 24,000 pounds...

OK, Kendra/Robynne/etc, let me ask, if the issue is airflow and optimising aerodynamics, do you think that weight makes a difference?

Then there is the question of training.  Do you think they would teach the pilots two ways of flying or one way of flying?

[sandiego89]

.

It needed it even when the weight was down to 16,000 or 18,000 pounds?  Sure it makes sense when the weight increased to 24,000 pounds...
[/quote]

Regardless of the weight, the Cutlass needed every trick available including the long nose gear needed for the required high angle of attack- it was overweight, underpowerred, long spool up time, and was flying off smallish carriers.     

[The Rat]

When it comes to the crappy performance of the 'Gutless Cutlass', and the various methods that were tried to wring something usable out of it, there are only two words needed: Westinghouse engines. 

[Daryl J.]

A patient of mine worked on the Cutlass and felt its chief weakness was the power plants.   I asked about the nose gear and his opinion was that it was indeed bad but not like the engines.   They would lose up to 1/3 of the aircraft  per flight.   At one point, if I recall correctly, they flew the Cutlass ashore and refused to fly them back aboard.   He was pretty clear, however, with better engines, it would have been an amazing machine for its time.

Unfortunately, he lives some 200 miles away now otherwise I'd cross check the above with him and try find out more.   

[rickshaw]

When it comes to the crappy performance of the 'Gutless Cutlass', and the various methods that were tried to wring something usable out of it, there are only two words needed: Westinghouse engines. 

Why settle for second-best when Rolls Royce are two perfectly respectfully better words that are available? 

[PR19_Kit]

When it comes to the crappy performance of the 'Gutless Cutlass', and the various methods that were tried to wring something usable out of it, there are only two words needed: Westinghouse engines. 

Why settle for second-best when Rolls Royce are two perfectly respectfully better words that are available? 

'Not invented Here' perhaps? 

[rickshaw]

When it comes to the crappy performance of the 'Gutless Cutlass', and the various methods that were tried to wring something usable out of it, there are only two words needed: Westinghouse engines. 

Why settle for second-best when Rolls Royce are two perfectly respectfully better words that are available? 

'Not invented Here' perhaps? 

Thats three words, Kit.   

[KJ_Lesnick]

sandiego89

Regardless of the weight, the Cutlass needed every trick available including the long nose gear needed for the required high angle of attack- it was overweight, underpowerred, long spool up time, and was flying off smallish carriers.

It wasn't overweight as initially conceptualized and was not underpowered at that point either.

It became underpowered and overweight as it got heavier... early on it was positively light.   I did some checking and the weights were even lighter than I thought.  If you compare the figures with the fact that the wing was the same size you get some real feather-light wing-loading figures.

Here are some figures for comparison...

I: XF7U-1

Weights
→ OEW: 9,565 lbs
→ Gross: 14,505 lbs
→ Maximum: 16,840 lbs*¹

Thrust
→ Dry Power: 2 x 3,700 lbf
→ Afterburning: 2 x 4,900 lbf

T/W Ratios
→ Maximum (Dry/AB): 0.4394/0.5819
→ Gross (Dry/AB): 0.5102/0.6756
→ Combat*² (Dry/AB): 0.5291/0.7822

Fuel Fraction
→ 34.0572%*¹

Aerodynamics
→ Aspect Ratio: 3.0143
→ Wing Loading (Maximum): 33.9516 lbs/ft²
→ Wing Loading (Gross): 29.244 lbs/ft²
→ Wing Loading (Combat*²): 25.2601 lbs/ft²

II: F7U-3M

Weights
→ OEW: 18,210 lbs
→ Gross: 26,840 lbs
→ Maximum: 31,643 lbs

Thrust
→ J46 Dry Thrust: 4,800
→ J46 Afterburning: 6,100 - 6,365 lbs *³

T/W Ratios
→ Maximum (Afterburner): 0.3856 - 0.4023
→ Maximum (Dry): 0.3034
→ Gross (Afterburner): 0.4545 - 0.4732
→ Gross (Dry): 0.3577
→ Combat*² (Afterburner): 0.5228 - 0.5455
→ Combat*² (Dry): 0.4113

Fuel Fraction
→ 32.1535%*¹

Aerodynamics
→ Aspect Ratio: 3.1723
→ Wing Loading (Maximum): 63.7964 lbs/ft²
→ Wing Loading (Gross): 54.1129 lbs/ft[/sup]2[/sup]
→ Wing Loading (Combat*²): 47.0524 lbs/ft²


III: Notes
*¹: It's the specified maximum load: I'm unsure if the plane carried drop tanks at this stage, but I did read about an F7U-1 that crashed with a 250 gallon tank; fuel fraction on the F7U-1 is based on the use of AvGas which is 6.02 lbs/gal; the F7U-3 on JP-5 which is 6.84 lbs/gal
*²: At the time I think the Navy used 60% as a combat weight figure, despite the fact that now 50% is used
*³: Based on listed thrust figures for the J34/J46 and afterburner figures, as well as proportional increases produced by other J34 and J46 variants respectively

[jcf]

As usual reality aint' so simple.

The Westinghouse 24C/J34 was actually a very successful early axial design, it was
based on the 1942 designed Westinghouse 19A 'Yankee' the first all US design, and
when designed in 1944-45 it's power output was impressive for a 24" diameter
engine. It served well for the life of the McDonnell Banshee and was OK in
the early versions of the F3D. The problem was that aircraft designs rapidly
got bigger and heavier and there was no growth room in the basic J34 design, so as
aircraft got heavier it's output didn't increase proportionally.
As to using a R-R engine in place of the J34, good luck fitting their big centrifugal engines
of the period into an airframe designed around a 24" diameter engine. 

The big flops were the all-new design J40 and the J34 based, with added Rolls-Royce tech
BTW, J46. The J40 failure for one had a huge impact as several aircraft had been designed
around it's promised performance.

As to the original question, paper numbers produced during the design phase in that era
are largely informed guesses, while based on available data, experience and utilizing empirical
methods, they were still guesses and targets they hoped to meet.

[JayBee]

How about this for an idea, it appeared in FSM some time ago but I have no idea who to credit it to.

[Chris707]

Vought also considered more conventional layouts for what became the F7U:



The V-346B, closer to a swept wing Pirate than what ended up being built as the Cutlass

[PR19_Kit]

How about this for an idea, it appeared in FSM some time ago but I have no idea who to credit it to.4

I like the look of that JayBee, take one Cutlass, mix in a bit of Tomcat, spray grey and white, and bingo!