Hawker P.1121 Question

[Zen9]

OK lets have a proper look
P1121 Air superiority strike aircraft
Length: 69ft 1"
Span: 37ft
Wing area: 474sqft
Weight: Gross 42,000lb
Speed: Sea Level mach 1.3, at 36,000ft mach 2.35
Powerplant: Gyron 25,000lb

P1121 two seater strike aircraft
Length: 67ft 8"
Span: 37ft
Wing Area: 474sqft
Weight: Gross 50,710lb
Speed: Sea Level mach 1.3, above 36,000ft mach 2.2
Powerplant: Olympus OL.21R for 29,000lb in reheat.

At max load 106lb per sqft

F4K
Length: 57ft 7"
Span: 38ft 4"
Wing Area: 530sqft
Weight: Gross 56,000lb

At max load 105.7lb per sqft

So in terms of wing loading the difference is slight at maximum permissible load on a RN carrier....though strictly the P1121 strike is well under that weight limit.

What is needed is TO and L speeds.....

 

[SsgtC]

OK lets have a proper look
P1121 Air superiority strike aircraft
Length: 69ft 1"
Span: 37ft
Wing area: 474sqft
Weight: Gross 42,000lb
Speed: Sea Level mach 1.3, at 36,000ft mach 2.35
Powerplant: Gyron 25,000lb

P1121 two seater strike aircraft
Length: 67ft 8"
Span: 37ft
Wing Area: 474sqft
Weight: Gross 50,710lb
Speed: Sea Level mach 1.3, above 36,000ft mach 2.2
Powerplant: Olympus OL.21R for 29,000lb in reheat.

At max load 106lb per sqft

F4K
Length: 57ft 7"
Span: 38ft 4"
Wing Area: 530sqft
Weight: Gross 56,000lb

At max load 105.7lb per sqft

So in terms of wing loading the difference is slight at maximum permissible load on a RN carrier....though strictly the P1121 strike is well under that weight limit.

What is needed is TO and L speeds.....

It's not just the wing loading, though that does play a part. It's the low speed handling characteristics. Carrier based aircraft need to be able to take off an trap back on the carrier at the lowest speeds possible. And they also need to have excellent handling characteristics at low speed. If the P.1121 has a higher takeoff speed than what the carrier, the wind over the deck and the catapults can provide then the plane isn't suited. It needs to generate more lift at low speed, which means a bigger wing.

As designed, the P.1121 was unsuitable for carrier operations. But what intrigues me about it, is that it was early enough in it's design cycle that I think it could have been developed into an outstanding carrier based fighter.

 

[KokkenKunten]

So in terms of wing loading the difference is slight at maximum permissible load on a RN carrier....though strictly the P1121 strike is well under that weight limit.

Those figures are meaningless and selective.

You're completely neglecting the fact that the FG.1 has 12,000lb more installed thrust, a wing designed from the outset for carrier operation and with the additional modifications of drooping ailerons, enlarged leading edge flaps, along with a slotted tailplane and increased flap and leading edge blowing to enable operation from an Audacious class.

 

[Zen9]

It's not just the wing loading, though that does play a part. It's the low speed handling characteristics. Carrier based aircraft need to be able to take off an trap back on the carrier at the lowest speeds possible. And they also need to have excellent handling characteristics at low speed. If the P.1121 has a higher takeoff speed than what the carrier, the wind over the deck and the catapults can provide then the plane isn't suited. It needs to generate more lift at low speed, which means a bigger wing.

As designed, the P.1121 was unsuitable for carrier operations. But what intrigues me about it, is that it was early enough in it's design cycle that I think it could have been developed into an outstanding carrier based fighter.

So if you have the figures do let us know.
Otherwise you are making as much an assumption as those who dare to ponder it's suitability for carrier operations.

mk 13 arrestor gear 101kts for 36,000lb plus 25kts WOD = 126kts @ 36KLB variations of this approximately 1kts = 1,000lb

Recovery @ fuel fraction of 10% internal fuel with all stores....?
fuel total 1,500gal = 12,000lb ergo 150gal = 1,200lb
GW inclusibe of shoes = 1,650lb
strike = 1,750lb ( Red Beard)
So only 100lb difference between one nuclear store and 4 Red Top.

2 by 300gal drop tank = 450lb + 2,400lb = 2,850lb therefor 5,700lb
2 by 200gal drop tank = 400lb + 1,600lb = 2,000lb therefor 4,000lb
Drop tanks Empty total 850lb
Total weight minus empty drop tanks 50,710lb - 8,000lb = 42,710
total weight minus 90% internal fuel = 31,910lb

At 31,910lb landing speed can be approximately 101kts + 25kts WOD + (4KLB less than 36KLB = 4kts) 121kts
Alternatively the carrier can slow by 4kts to 21kts or can land with a 4kts natural wind from astern.

But without the aircraft figures this is pure speculation. We need CLMax figure.
However the use of autothrottle and BLC could cut landing speed by 9kts

 

[Zen9]

Those figures are meaningless and selective.

You're completely neglecting the fact that the FG.1 has 12,000lb more installed thrust, a wing designed from the outset for carrier operation and with the additional modifications of drooping ailerons, enlarged leading edge flaps, along with a slotted tailplane and increased flap and leading edge blowing to enable operation from an Audacious class.

So the most logical design variant is the one with blow and droop like the F4K.

However.....F4K has a high empty weight of 31,000lb
A product of using two engines among other things.
I'd also be careful about certain assumptions, the F4 has a higher leading edge sweep angle.
Though to be fair the tail surfaces pick up lift and thrust in that position.

 

[KokkenKunten]

So the most logical design variant is the one with blow and droop like the F4K.

However.....F4K has a high empty weight of 31,000lb
A product of using two engines among other things.
I'd also be careful about certain assumptions, the F4 has a higher leading edge sweep angle.
Though to be fair the tail surfaces pick up lift and thrust in that position.

No. The most logical design variant would be one which isn't P.1121.

The FG.1 does indeed have a higher empty weight, however, this is apropos of absolutely nothing. I'm aware of precisely no aircraft ever operating at their empty weight - much less doing so from a carrier.

A product of common sense, amongst other things.

T/W ratio is what you should be considering which, under all scenarios, vastly favours the Phantom.

Telling me that the leading edge of the FG.1 wing is swept at a greater angle than that of the P.1121 is utterly irrelevant - all characteristics of an aerofoil must be considered to generate meaningful data concerning lift / drag coefficient.

Perhaps you can explain what you mean by "...to be fair the tail surfaces pick up lift and thrust in that position" & what calculations / datum you've used to reach that conclusion. I'd particularly like to see how you've concluded that the horizontal stabilisers produce thrust.

It seems that only one of us is making 'certain assumptions' here, and it certainly isn't me.

 

[Zen9]

So first off, you could keep the attitude.
This thread is a musing on the P1121, and it's quite acceptable to ponder it's navalisation however far from the basic design that goes.

Secondly you are right that thrust to weight ratio is important and that the P1121 is lower than a F4K, though higher than a Buccaneer or Sea Vixen I might note.

Thirdly you also right that the specifics of the wing are key, however a general rule of thumb is that the more sweep back, the higher the flying speed for a given aircraft.
In the case of the F4 this is actually a Delta, though not a 60 degree one if memory serves and that comes with some benefits and some costs.
I might note that someone claims the P1121 wing is the same a Hunter, I suspect that is quite an assumption.

As for the tail configuration....I remember reading this yonks ago, but digging out the reference is no small task.

Anyway if someone has the TO & L speeds predicted for the P1121....they are holding it back.

 

[KokkenKunten]

So first off, you could keep the attitude.
This thread is a musing on the P1121, and it's quite acceptable to ponder it's navalisation however far from the basic design that goes.

Secondly you are right that thrust to weight ratio is important and that the P1121 is lower than a F4K, though higher than a Buccaneer or Sea Vixen I might note.

Thirdly you also right that the specifics of the wing are key, however a general rule of thumb is that the more sweep back, the higher the flying speed for a given aircraft.
In the case of the F4 this is actually a Delta, though not a 60 degree one if memory serves and that comes with some benefits and some costs.
I might note that someone claims the P1121 wing is the same a Hunter, I suspect that is quite an assumption.

As for the tail configuration....I remember reading this yonks ago, but digging out the reference is no small task.

Anyway if someone has the TO & L speeds predicted for the P1121....they are holding it back.

It strikes me as strange (and not at all helpful) that we live in a time where a firm rebuttal based upon fact might be considered 'attitude'. Nonetheless, I'll keep my 'attitude' if you can stop posting erroneous assumptions which aren't supported by that which is known, along with accepting when you're wrong without obfuscation.

Any iteration of P.1121 modified - by which, we mean 'fundamentally redesigned' - to allow operation from ANY carrier (much less the Audacious class) will be so different as to no longer BE P.1121, and certainly would not be categorised by the manufacturer with that nomenclature.

The reason we're discussing T/W is primarily because you chose to include selected weights - more than a few of which are incorrect, as I've already stated. Regardless, none of this changes by one iota, the fact that the P.1121 wing is wholly unsuited for carrier operations. As you've seen fit to bring both Buccaneer and Sea Vixen to the discussion as exemplars, let us remember that even Buccaneer (max weight off the cat - 56,000lb) has a bigger wing - which was specifically designed for carrier operations and has full BLC, whilst Sea Vixen (max weight off the cat - 47,000lb) is basically one giant flying surface. T/W, as important as it may be, is not the primary consideration here - wing design and size are.

And by the way, no - one "claims the P1121 wing is the same (as) a Hunter". It was me who brought this up in respect of the aerodynamic design principles (and structure, for that matter), and the exact phrase I used was "fundamentally based on that of the Hunter". If you take a moment to check, the veracity of this statement is borne out by virtually every authoritative piece I've ever seen on P.1121.

I'f you honestly believe that a tail plane actively produces thrust, you'll forgive me for thinking we won't be able to have any meaningful discussion about wing design or aerodynamics in the more general sense.

 

[Zen9]

Firstly you may request what you like.

Any iteration of P.1121 modified - by which, we mean 'fundamentally redesigned' - to allow operation from ANY carrier (much less the Audacious class) will be so different as to no longer BE P.1121, and certainly would not be categorised by the manufacturer with that nomenclature.

You are suggesting that the entirety of the P1121 design would need complete redesign there.
What I'm suggesting is this mostly confines itself to the wing and tail, in it's need for blow and droop on the wing leading edge.and likely some blow over tail and fin.

What weights are incorrect?

Wing area for the Buccaneer is 508.5sqft or about 34sqft more than the P1121. Considering the wingloading this is not that different.

The tail on the F4 picks up lift and thrust from the engine exhaust, I'm fairly sure that's what I've read.
It doesn't generate thrust on it's own, which I'm pretty sure I haven't said....."Though to be fair the tail surfaces pick up lift and thrust in that position." rather implies it gets something from it's location, above and behind the engine nozzles.

 

[SsgtC]

The tail on the F4 picks up lift and thrust from the engine exhaust, I'm fairly sure that's what I've read.
It doesn't generate thrust on it's own, which I'm pretty sure I haven't said....."Though to be fair the tail surfaces pick up lift and thrust in that position." rather implies it gets something from it's location, above and behind the engine nozzles.

Not really accurate. The tail surfaces do not "pick up thrust." Thrust is only generated by the engines. I believe you may be getting some terms incorrect. You're saying "thrust" when what you're meaning is "airflow." Two very different things.

At any rate, no the horizontal tail generates no lift for the aircraft. IIRC, it's actually designed to be essential neutral, neither generating lift nor reducing lift. All fighters from the 1950s on have had "all moving" tailplanes. Meaning the entire thing will either swivel from side to side for yaw or up and down for pitch. Having the horizontal stabiliser generate lift would actually be constantly forcing the aircraft into a nose down orientation. Why? Because the tail would now be trying to pick up the ass end of the plane. That would cause some...interesting...effects.

 

[riggerrob]

I disagree that F4K’s horizontal tail produces lift.

First off, lifting tails were extremely rare back in the Phantom’s day. Most airplanes are stabilized by opposing forces: the centre of gravity is slightly forward of the centre of lift so tries to force the nose down. Meanwhile the horizontal tail produces an equal and opposite nose-up force. This only works if the tail pushes the aft end DOWN.
Modern fighters can only do that with the centre of gravity well aft. An aft C. of G. makes them more efficient and more maneuverable. The down side is that an aft C. of G. makes them so unstable, that they need full-time auto-pilots the reduce the work load for pilots. If the C. of G. is too far aft, they never recover from stalls or spins.

Secondly, F4K has a slotted horizontal tail. Slots smooth airflow over the BOTTOM of the horizontal tail, meaning MORE downward force generated by the tail.
Thirdly, American sailors complained about F4K after-burners warping deck plates, but Brits never complained about warped tailplanes. Photos of F4K after-burners - just before the catapult flings them off the deck - show the flames hitting the deck but still well below tailplanes.

 

[Zen9]

Well if anything could make me regret a passing comment in favour of the F4, then the sight of this hijacking a thread considering the reasonable proposition of could the P1121 be navalised is certainly it.

 

[The Wooksta!]

P.1121 was indeed looked at for the naval strike role, a two seat side by side version with folded wing was drawn by J D Mills 15 April 1958.

The Gyron was ruled out as an engine for any production version due to unsolvable problems with the intake - an engine was run repeatedly with a dummy intake and despite modifications, constant problems with surging occurred - the RAE suggested that the engine was too sensitive to disrupted airflow - so HSA opted for the Olympus instead. However, production of that engine was some time away and an aircraft without an engine is just a heap of spare parts, so construction slowed then finally stopped.

I strongly recommend "Hawker P.1103 & P.1121: Camm's Last Fighter Projects" by Paul Martell-Mead and Barrie Hygate. Blue Envoy Press ISBN 978-0-9561951-5-9

 

[Zen9]

I dimly recall reading they got huge surges on the Gyron, but the author was using the figures to suggest just how powerful the Gyron was, something like 29,000lb of thrust..?

When my budgets permit that book is on my list of 'to get' items.

 

[The Wooksta!]

I'd also recommend Barrie Hygate's "British Experimental Jet Aircraft", as there's a good section on P.1121 with 72nd plans (used to do the Maintrack 72nd vacform kit in the 90s - it's currently available from Whirlybird. Nice kit). However, it's like rocking horse shite to find.

Derek Wood's "Project Cancelled" is also worth a read, but he was a right wing aviation journalist and it's quite a biased book.

 

[Lord Wyclif]

I’ve a brilliant way of resolving these disagreements. Let’s kill of the RN Carrier Force and use imaginary airfields to launch TSR2 sorties.

 

[Zen9]

I’ve a brilliant way of resolving these disagreements. Let’s kill of the RN Carrier Force and use imaginary airfields to launch TSR2 sorties.

I have a soft spot for the sort of giant Bomber destroyer types a.k.a Red Barrel, Delta Scorpion, and Tu-22 Fiddler.

 

[Zen9]

I'm in luck! Digging through my papers I was rather interested to revisit a certain paper on AW.406 in search of the resources for a proper debate on an 'ideal' RN CV compatible aircraft.....
So I came across the source for my previous statement.

Technical Memorandum No. Aero 797
June 1963 (likely declassified by 2013)
Comparison of the four types of naval interceptor to meet the AW.406 Requirement
By J.R. Collingborn
(my bold)

"In the case of aircraft 'A', 'C', and 'D', the two propulsive engines are assumed to be installed side by side in the rear fuselage, with propelling nozzles in the low position below the tail unit and forward of the fuselage extreme rear, (again as on the Phantom). Compared with nozzles located at the rear of the fuselage this arrangement has the dual advantage that it increases the contribution of the engine thrust to lift at take-off and during the transonic acceleration, and also provides surface area behind the nozzles to pick up post-exit thrust at supersonic speeds."

It's possible that while the F4 might not actually achieve that, this is the source of my dimly remembered knowledge that drove my comment.
Perhaps someone with good knowledge of the F4 aerodynamics could confirm or deny that?

 

[tomo pauk]

...
"In the case of aircraft 'A', 'C', and 'D', the two propulsive engines are assumed to be installed side by side in the rear fuselage, with propelling nozzles in the low position below the tail unit and forward of the fuselage extreme rear, (again as on the Phantom). Compared with nozzles located at the rear of the fuselage this arrangement has the dual advantage that it increases the contribution of the engine thrust to lift at take-off and during the transonic acceleration, and also provides surface area behind the nozzles to pick up post-exit thrust at supersonic speeds."

It's possible that while the F4 might not actually achieve that, this is the source of my dimly remembered knowledge that drove my comment.
Perhaps someone with good knowledge of the F4 aerodynamics could confirm or deny that?

Neat find.
Until the expert(s) chime in, here is my take: the fuselage surface next to the exit works as a 'fulcrum' that exhaust gasses are 'supporting'? So the exhaust gasses, exiting partilally in all directons, will try and accelerate the fuselage, and with it the complete aircraft.

 

[SsgtC]

Neat find.
Until the expert(s) chime in, here is my take: the fuselage surface next to the exit works as a 'fulcrum' that exhaust gasses are 'supporting'? So the exhaust gasses, exiting partilally in all directons, will try and accelerate the fuselage, and with it the complete aircraft.

Yeah, that's kinda how I read it. That the upper fuselage helped to direct the thrust down and aft. Kind of like a primitive, unmoving form of thrust vectoring.