Lemonade out of Lemons: Making Bad Aircraft Good

[KJ_Lesnick]

I posted a thread about this awhile back and I was thinking of designs that had a lot of potential if only a few changes were made

One I can think of is the F7U-1: The most basic changes that would have made the most sense would have been

• Design the main-landing gears so they were perpendicular with the wing: It basically gave more control surface leverage and didn't require a variable position set-up
  
• Use a simpler arrester hook that as mounted from the bottom rather than the top: I'm not sure why they had the more complicated arrester gear set-up
  
• Reshape the nose as on the F7U-2: I'm unsure why they didn't realize they'd have visibility problems (unless they didn't factor in AoA)
  

Other things that would have been useful would have been to use smaller chord slats (not sure by how much) but it would lower the required AoA on the ground, and in turn shortened the nose-gear leg.  The only problem I could see would be that it could conceivably eliminate a great quality the F7U had -- it wouldn't stall when slats were out (the F7U-3 would most certainly stall when they were in; the F7U-1 wouldn't because it lacked control power), much like the Me-163B.

[rickshaw]

What the entire F7U series required most were new engines.   Their aerodynamics weren't great for a carrier aircraft either.  The reason why they need to extend their noseleg was because deltas require a high AoA when taking off or a long runway to build up speed.   Without either, there is insufficient airflow over the wing for them to work properly at lower speeds.

[KJ_Lesnick]

rickshaw,

Their aerodynamics weren't great for a carrier aircraft either.  The reason why they need to extend their noseleg was because deltas require a high AoA when taking off or a long runway to build up speed.

Yes, but the F4D had a lower aspect ratio and didn't require as big a nose-gear.  Part of it had to do with the slats.

What the entire F7U series required most were new engines.

The weight creeped up a lot...   

[rickshaw]

rickshaw,

Their aerodynamics weren't great for a carrier aircraft either.  The reason why they need to extend their noseleg was because deltas require a high AoA when taking off or a long runway to build up speed.

Yes, but the F4D had a lower aspect ratio and didn't require as big a nose-gear.  Part of it had to do with the slats.

Slats were one solution.  The F4D also had a better engine than the F7.  More reliable and less prone to stalls.    The F4D still however required increased AoA at take off, hence the extending noseleg.  Blown flags/wings would be the ultimate solution to generating lift at low speeds.

What the entire F7U series required most were new engines.

The weight creeped up a lot...
[/quote]

Weight was not it though.  Their engines were crap from the start.   They'd have been better off putting some Avons in them.

[Rheged]

Reading the thread title puts me in mind of an entry in the Carlisle Canal Engine Shed daybook.  In the section of the book devoted to possible repairs and improvements for individual engines, someone had written:-

"The whistle of engine 60079 needs attention.............................. it needs jacked up and a new locomotive installed underneath it"

There are limits even to the production of lemonade!!! 

[Weaver]

rickshaw,

Their aerodynamics weren't great for a carrier aircraft either.  The reason why they need to extend their noseleg was because deltas require a high AoA when taking off or a long runway to build up speed.

Yes, but the F4D had a lower aspect ratio and didn't require as big a nose-gear.  Part of it had to do with the slats.

Slats were one solution.  The F4D also had a better engine than the F7.  More reliable and less prone to stalls.    The F4D still however required increased AoA at take off, hence the extending noseleg.  Blown flags/wings would be the ultimate solution to generating lift at low speeds.

What the entire F7U series required most were new engines.

The weight creeped up a lot...

Weight was not it though.  Their engines were crap from the start.   They'd have been better off putting some Avons in them.
[/quote]

That'd mean a major redesign: the Avon is nearly 8 inches wider than the J46.

[sandiego89]

The F7U's nose-gear was already high enough, I'd say the telescoping feature wasn't needed as it was used only for catapults -- if the catapult can fling you into the air fast, I see little point...
[

The telescoping nose was needed, or it would not have been put on there.  The Cutlass needed every trick in the book to get airborne from the WWII era aircraft carriers.  Remember it was underpowered, heavy, and was being catapulted with early hydraulic (and some steam) catapults with limited stroke length and power.  Speed at the end of the stroke is only one factor.   You need to account for airspeed, weight, power, height above water, atmospheric conditions, acceleration, drag, angle of attack (lift), wind, etc. A Cutlass launched nose level would have run out of several things rather quickly at the end of the stroke if it was not at the proper angle of attack.   

[KJ_Lesnick]

I was thinking about a couple of things, which were presented by several members

Engines: I don't recall any significant problems with the J34's in terms of reliability (at least above any other engine), and seemed to do fine on the F2H, and even the F3D (though it was underpowered).  The afterburner proposal seemed largely to do with the Solar company dawdling around.  It seems there's probably some wisdom in having the engine manufacture be responsible for designing the afterburner the engine is to use.  There were other domestic engines such as the J35 and J47 which both would have added some extra thrust, despite being somewhat larger in diameter.  As for the foreign engines, I'm not sure how keen we would have been in buying the Avon (which was running first).

Nose-Up Attitude: While part of the reason for the nose-up attitude had to do with the basic wing cross-section, part of it with the low aspect-ratio, part of it with the slats, and for catapult-shots, the extending gear strut.  I don't know how many degrees nose-up the F7U sits, but the XF5U seemed to be pretty high up.  I'm curious how they compare.

Aerodynamics: I remember something about the F7U being designed with a thicker wing with almost no camber for some reason.  I'm curious if using a more cambered foil like the F-86 would have allowed the aircraft to get through Mach 1 in a dive without excessive trim-control problems.  It seems like it would have produced more lift at zero-alpha, and might have helped out the design.

Other: The F7U had a lot of gadgets including

• A strange arrester hook mounted up top instead of from below: Originally it was aimed at dealing with pitching-movements, but it eventually included the ability to jettison the whole hook for some reason.  As time went on, it was repositioned down below
  
• A main-landing gear arrangement who's wheels would be angled back for landing on the deck, and taxiing to avoid pitching back into the water, and being aimed forward (perpendicular to the frame) allowing more elevator control.  The F7U-3 had a simpler gear design that eliminated this, and was simply perpendicular and seemed less complicated.
  

Among others, and the problem is excessive complexity could serve to add a lot of weight to the plane, which was a problem.

[PR19_Kit]

Nose-Up Attitude: While part of the reason for the nose-up attitude had to do with the basic wing cross-section, part of it with the low aspect-ratio, part of it with the slats, and for catapult-shots, the extending gear strut.  I don't know how many degrees nose-up the F7U sits, but the XF5U seemed to be pretty high up.  I'm curious how they compare.

I think you may have the cause and effect the wrong way round concerning the nose gear strut. It was tall because it NEEDED to be to produce the nose high angle.

As for the ground angle of the two types, see below.

XF5U-1 = 21 deg

F7U-3 = 13 deg

That wasn't the result of delving deep into Chance Vaught's corporate archives, just 5 mins spent with graphics software and two good side views of the two types.

[KJ_Lesnick]

I think you may have the cause and effect the wrong way round concerning the nose gear strut. It was tall because it NEEDED to be to produce the nose high angle.

I was just addressing the issues.  I know they were out of somewhat out of sequence.

As for the ground angle of the two types, see below.

XF5U-1 = 21 deg

F7U-3 = 13 deg

Then why was the F7U a problem?

[PR19_Kit]

I think you may have the As for the ground angle of the two types, see below.

XF5U-1 = 21 deg

F7U-3 = 13 deg

Then why was the F7U a problem?

The Flying Pancake can't be compared to anything else, it used a totally different aerodynamic concept and used the enormous propwash over the almost square wing to produce high lift  at very low speeds. The Cutlass was meant to be supersonic.

You may as well compare an airship with an F-104.

[KJ_Lesnick]

The Flying Pancake can't be compared to anything else, it used a totally different aerodynamic concept and used the enormous propwash over the almost square wing to produce high lift  at very low speeds. The Cutlass was meant to be supersonic.

So AoA on landing?

[rickshaw]

The Flying Pancake can't be compared to anything else, it used a totally different aerodynamic concept and used the enormous propwash over the almost square wing to produce high lift  at very low speeds. The Cutlass was meant to be supersonic.

So AoA on landing?

Take off, more likely.  The Cutlass like most tail-less/delta winged aircraft had problems gaining sufficient lift during take off.   

[PR19_Kit]

The Flying Pancake can't be compared to anything else, it used a totally different aerodynamic concept and used the enormous propwash over the almost square wing to produce high lift  at very low speeds. The Cutlass was meant to be supersonic.

So AoA on landing?

How would ANYone know? The Pancake never flew!

[jcf]

The Flying Pancake can't be compared to anything else, it used a totally different aerodynamic concept and used the enormous propwash over the almost square wing to produce high lift  at very low speeds. The Cutlass was meant to be supersonic.

So AoA on landing?

How would ANYone know? The Pancake never flew!

The V-173 Zimmer's Skimmer did fly, and proved the concept.

https://oldmachinepress.com/2017/01/20/vought-v-173-flying-pancake-zimmers-skimmer/