SR.177 Could it have been a success?

[uk 75]

I admit to hating this aircraft as being underarmed and hopelessly compromised by its rocket engine. It was obsolete before it flew and yet the similar but more sensible F104 Starfighter went on to become NATO's standard interceptor and strike aircraft from Canada to Turkey.
I know the SR177 has many fans (as many as P1121?) so I am willing to listen to how it could have succeeded.

 

[Rule of cool]

Remove the rocket and replace the Gyron Jr with a Spey and make sure it has the hardpoints to carry 6,0000lbs worth of bombs.

 

[Scott Kenny]

How did the SR177 end up so far "behind" the F104?

Development of both started about the same time in 1952. But the F104 had a J79 and no rocket, while the SR177 had a Gyron Jr with roughly the same power as the J79 plus a rocket.

As to operational success, I'd start with missiles that were as simple and reliable as Sidewinders.

 

[Michel Van]

So far i know the Germans wanted the SR.177
and were developing a rocket engine for it: the P111 kerolox, high pressure, staged combustion cycle.

SR.177 was victim of infamous the 1957 Defence White Paper, which called for crewed combat aircraft to be replaced by missiles.
after that rotten paper was out, the OR.337 was cancelled
while SR.177 prototype was 90% completed at Saunders-Roe

and then came the Germans.
They were furious because they needed the SR.177 as backbone for there Airforce
The Germans wanted the Rolls-Royce RB.153 engine instead the Gyron Jr, also they demanded SR.177 as a strike fighter instead.
Saunders-Roe start hasty modification on SR.177

in mean time were political in-fighting about SR.177, between the Minister of Supply Aubrey Jones and
Baron Duncan Sandys, the moron behind the infamous the 1957 Defence White Paper.
While Heinkel preparing to manufacture the SR.177 locally under licence,
Japan show also interest on SR.177 if get build.

and here went everything wrong, i don't by wrong translation or miss understanding...
the Germans demanded the arrangements to be between governments, instead of between the germans and Saunders-Roe.

In December 1957 the Germans step out SR.177 program and buy the F-104G (G for Germany) instead.

 

[Archibald]

A couple issues about a rocket on a plane is a) the crazy propellant consumption and b) finding a viable oxidizer. The latter is an almost impossible issue to solve.
-LOX is a deep cryogen, and that sucks for a fighter plane.
-H2O2 is liquid at room temperature, but potentially unstable and explosive.
-N2O is mild cryogen but performance sucks (and it need high pressure tankage, plus Virgin 2007 blast that killed 3 people).
-N2O4 is a toxic bastard, corrosive demon.

And that's it, no more reasonable option. The French SEPR rocket packs went with N2O4, and it worked well enough for Mirage IIIS. NF-104A bit the bullet and went with H2O2, but paid a price (corrosion and explosions). Others tried LOX.

Unless one try mixing a few of the above. Easier said than done ! But recently one very smart engineer fine-tuned a mix of LOX and N2O, calling it nytrox. No longer a deep cryogen like LOX, still with better performance than N2O.

 

[zen]

I admit to hating this aircraft as being underarmed and hopelessly compromised by its rocket engine. It was obsolete before it flew and yet the similar but more sensible F104 Starfighter went on to become NATO's standard interceptor and strike aircraft from Canada to Turkey.
I know the SR177 has many fans (as many as P1121?) so I am willing to listen to how it could have succeeded.

Personally it's just a airplane, so passions be only roused over esthetics. The looks.
So I don't understand the hatred.

In the context of the times and it's potential flexibility. It's what was on the table for a light Fighter Attack type system for both RAF and FAA from a domestic source that was funded.
That's it.
No passions really.

And as a compromised type, using jet only with large internal fuel tankage, maybe a different engine. It's......
good enough.

Not ideal.
But it's what was on the table.

So I don't understand that the near religious hostility to this alternative.

 

[Michel Van]

Why was so interest to equip interceptors with rocket engine in 1950s ?

The 1950s jet-engines were not so powerful as today ones
and they need interceptors be fast at high altitude, something you can make with rocket engine
what let to Saunders-Ro SR.53 and SR.177, Avro 720, SNCASO SO.9000, Republic XF-91 and SNCASE SE.212

but in same time came improvement in jet-engines and aerodynamics
what let to F-104, Mirage III, English Electric Lightning who could make the mission without rocket engine.

I guess at some point they would build SR.177 without rocket engine but better Jet-engine and more fuel.

 

[Scott Kenny]

Why was so interest to equip interceptors with rocket engine in 1950s ?

The 1950s jet-engines were not so powerful as today ones
and they need interceptors be fast at high altitude, something you can make with rocket engine
what let to Saunders-Ro SR.53 and SR.177, Avro 720, SNCASO SO.9000, Republic XF-91 and SNCASE SE.212

but in same time came improvement in jet-engines and aerodynamics
what let to F-104, Mirage III, English Electric Lightning who could make the mission without rocket engine.

I guess at some point they would build SR.177 without rocket engine but better Jet-engine and more fuel.

And yet the F-104 had the same climb performance that the SR177 was supposed to have.

And the F-104 was designed at exactly the same time as the SR177...

 

[Michel Van]

And yet the F-104 had the same climb performance that the SR177 was supposed to have.
And the F-104 was designed at exactly the same time as the SR177...

That difference between the British Gyron Jr and US General Electric J79 turbojet engine,
while SR.177 weight 11696 kg, was weight of F-104 9365 kg
Also play Clarence L. "Kelly" Johnson a mayor part here, special in the Design and construction of F-104.

 

[Scott Kenny]

That difference between the British Gyron Jr and US General Electric J79 turbojet engine,
while SR.177 weight 11696 kg, was weight of F-104 9365 kg

SR177 with the rocket running had almost 50% more thrust than the F-104 (both jets in afterburner).
SR177 14k+10k
F104 ~16k.

Yet the F-104 is 24 seconds faster to 12km! It's only above 12km/40k that the SR177 finally makes up altitude and catches up to the F-104 somewhere around 16 or 17km.

Also play Clarence L. "Kelly" Johnson a mayor part here, special in the Design and construction of F-104.

Yes, it probably doesn't help the SR177 when the Patrol Saint of Aircraft Engineers is working for the other team. But I'd argue that's mostly in the fine detail work to get the aerodynamic trim worked out so that the plane has as little drag as possible. Which shows up at altitude when the SR177 has a huge horsepower advantage.

 

[pathology_doc]

The rocket keeps running at an altitude where the jet has simply given up. That's the advantage of hybrid power.

I'd start with missiles that were as simple and reliable as Sidewinders.

We'll never know just how good Firestreak was, since it was never fired in anger. In favour of Firestreak is that the warhead is 50lb at a time when early Sidewinders still had 10lb, and I don't think any Sidewinder ever went above 25lb in all the years Firestreak was in service. Firestreak at release has five times the warhead (never less than two times) for a little over twice the all-up weight.

 

[zen]

Yet the F-104 is 24 seconds faster to 12km! It's only above 12km/40k that the SR177

Based on what?

 

[Scott Kenny]

The rocket keeps running at an altitude where the jet has simply given up. That's the advantage of hybrid power.

Exactly, but even with such a huge power advantage at altitude, it's just barely catching the F-104 at somewhere around 16-17km (I don't have time-to-height tables with equal heights for the two types).

Based on what?

The time-to-altitude tables on wiki. The F-104 holds FIA record number 9104, for a 99.90sec time to reach 12km. Saro estimates for the SR177 had it reaching 12km in 123sec.

We'll never know just how good Firestreak was, since it was never fired in anger. In favour of Firestreak is that the warhead is 50lb at a time when early Sidewinders still had 10lb, and I don't think any Sidewinder ever went above 25lb in all the years Firestreak was in service. Firestreak at release has five times the warhead (never less than two times) for a little over twice the all-up weight.

Much bigger, much heavier support systems needed in the aircraft, though.

Remember, Sidewinder is the original APKWS. It started life as a guidance pack for a Zuni rocket!

 

[PMN1]

As has been said.....remove the rocket part........making it look like the F-16 may help...

 

[Rule of cool]

As has been said.....remove the rocket part........making it look like the F-16 may help...

Obviously the cooler it looks the better it will be, that just stands to reason!

 

[pathology_doc]

The F-104 holds FIA record number 9104, for a 99.90sec time to reach 12km. Saro estimates for the SR177 had it reaching 12km in 123sec.

Stock or stripped race config?

 

[red admiral]

In favour of Firestreak is that the warhead is 50lb at a time when early Sidewinders still had 10lb, and I don't think any Sidewinder ever went above 25lb in all the years Firestreak was in service. Firestreak at release has five times the warhead (never less than two times) for a little over twice the all-up weight.

The UK AAMs had a larger warhead at this point because their miss distance was greater. The larger warhead didn't make them more lethal. Have a look in Forbat's Vickers Guided Weapons for more detail - this was a really big driver for Red Dean and Red Hebe.

 

[Zoo Tycoon]

The UK AAMs had a larger warhead at this point because their miss distance was greater. The larger warhead didn't make them more lethal. Have a look in Forbat's Vickers Guided Weapons for more detail - this was a really big driver for Red Dean and Red Hebe.

My 101 course in guided weapons design, admittedly from the mid eighties, said starting with the customer requirements for the size of the defended airspace/likely threats, you first run a study of the preferred (or competing) guidance systems to assess the (probabilistic) miss distance. This defines the warhead size. The proportion of the guidance system installed in the flight vehicle and the warhead are the flight vehicle payload and hence all other aspects of the missile itself, propulsion, aero, actuation are then sized appropriately.

In a way the brilliance of Sidewinder was they adopted another approach, ie keep the guidance package and warhead small enough to fit on the nose of a 3inch rocket… whatever it takes, and keep the project running long enough to evolve, by learn/redesign to become a highly effective system.

Nowadays the pre project modelling can be preformed to a standard beyond the dreams of the chaps in the 50-60’s it’s all optimised to really minimal sizes so the Sidewinder approach is sadly obsolete. However maybe we’re seeing a similar thing going on with low cost drones.

 

[Scott Kenny]

Stock or stripped race config?

Valid question, but it sounds like it was a stock F-104C. May not have been carrying sidewinders for that flight, however.

 

[Zoo Tycoon]

SR177 with the rocket running had almost 50% more thrust than the F-104 (both jets in afterburner).
SR177 14k+10k
F104 ~16k.

Yet the F-104 is 24 seconds faster to 12km! It's only above 12km/40k that the SR177 finally makes up altitude and catches up to the F-104 somewhere around 16 or 17km.

Not a valid comparison, the SR177 performance includes the carriage of weapons, weapon systems, maximum operating range fuel, while the F104 performance was for a special flight condition optimised for getting a record in that it didn’t match any of the SR177 configuration.

https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1015&context=aerosp

 

[pathology_doc]

starting with the customer requirements for the size of the defended airspace/likely threats, you first run a study of the preferred (or competing) guidance systems to assess the (probabilistic) miss distance. This defines the warhead size.

IIRC the basic threat the British AAMs were designed around was the Tu-4, an aircraft the British knew very well because (a) it was a ripoff of an allied nation's aircraft and (b) they themselves operated it as the Washington.

Per Ron Westrum's Sidewinder: Creative missile development at China Lake, the Sidewinder team were left rather disturbed after one of their early test articles blew a massive hole in the wing of a B-17 drone but failed to shoot the aircraft down (the control team were able to fly it back to a landing). Someone told the team leader "Don't worry, they don't build them this tough any more."

I would imagine the B-29 was an even tougher proposition than the -17, though.

 

[starviking]

The UK AAMs had a larger warhead at this point because their miss distance was greater. The larger warhead didn't make them more lethal. Have a look in Forbat's Vickers Guided Weapons for more detail - this was a really big driver for Red Dean and Red Hebe.

But I also recall from a thread somewhere on the forum that the US kill metric for AAMs was mission kill, the UK target destroyed.

In that case US and UK lethality is going to be different, with the UK missiles being more capable, if they’re ‘on target’, than the US ones.

 

[Rule of cool]

It's not as if the US AAMs were a story of unbridled success. The Falcon was a total dud, and the USAF was basically bailed out by buying USN missiles and fighters and even then these weren't the wonder weapons the Aim9L became 15 years later. Sure the Aim9B was better than the Aim4 and Aim7 in Vietnam, but this was a very low bar indeed, its not as if a ~9% success rate in combat is anything other than a problem.

Nor should the Firestreak be compared to the Aim9, it is a much bigger missiles akin to the Matra 530 and Aim7 Sparrow, neither covering themselves in glory in fighter vs fighter combat in the 60s.

 

[Scott Kenny]

Nor should the Firestreak be compared to the Aim9, it is a much bigger missiles akin to the Matra 530 and Aim7 Sparrow, neither covering themselves in glory in fighter vs fighter combat in the 60s.

It's a 6-10km range missile that is IR guided.

That's Falcon or Sidewinder, not Sparrow.

 

[Rule of cool]

I don’t buy that, missile (like aircraft) range is the most variable thing on earth, even comparing apples to apples is difficult. Also I said the Firestreak approaches (not matches) the contemporary R530 and Sparrow.

While the contemporary Aim7D had an aerodynamic range of 44km at 40,000’ apparently the seeker range was only 15km. The maximum range of the Aim9B was 4.8km, so I struggle to believe the 20% smaller Aim4 had double the range despite the smaller warhead and lack of proximity fuse.

The bigger and 10% slower R530 appears to have a 20km max range, however like the sparrow and sidewinder max figures these are in ideal conditions.

The Firestreak’s 6-10km range is comfortably double the 9b, and I suspect the Aim4c/d. A Firestreak armed fighter can do things a sidewinder and falcon armed fighter cannot, in theory of course as we know what happened in practice.

 

[pathology_doc]

I don’t buy that, missile (like aircraft) range is the most variable thing on earth, even comparing apples to apples is difficult. Also I said the Firestreak approaches (not matches) the contemporary R530 and Sparrow.

While the contemporary Aim7D had an aerodynamic range of 44km at 40,000’ apparently the seeker range was only 15km. The maximum range of the Aim9B was 4.8km, so I struggle to believe the 20% smaller Aim4 had double the range despite the smaller warhead and lack of proximity fuse.

The bigger and 10% slower R530 appears to have a 20km max range, however like the sparrow and sidewinder max figures these are in ideal conditions.

The Firestreak’s 6-10km range is comfortably double the 9b, and I suspect the Aim4c/d. A Firestreak armed fighter can do things a sidewinder and falcon armed fighter cannot, in theory of course as we know what happened in practice.

A defence of the Falcon, by its intended user flying the intended launch aircraft:

View: https://youtu.be/jzi-SFqEScY?si=t2jVeRKts4XbCo6_
See the comments.