1945-1950 All Weather Close Air Support Jet

[Pellson]

The USAF fixed the the three main problems with the Canberra - poor vision, poor air brakes and the bomb bay doors

I assume poor-vision had to do with the weird cockpit set-up; I'm unsure what kind of air-brakes the Canberra had to begin with; and I honestly have no idea what problems existed with the Canberra's bay...

Invariably also the original Canberra would have benefited from Martins take on the cockpit arrangements. However, it was at the time envisaged by the Air Staff that the Navigator/Bombardier shouldn't be disturbed unnecessarily by any interfering reality ongoing outside of any tactical aircraft, hence the ubiquitous "coal hole" present not only on the later British Canberras but also on the Sea Vixen. That said - the pilots view was at least as good in the Canberra B(I).8 as in the B-57B.
While the B(I).8 had a definite need to put the pilot offset (to allow the nav/bombardier to crawl forward to his nav station), the PR.9 could very well have relocated the pilot to a central position as the navigator in that case was permanently seated on a bang seat all in front of the pilot compartment. I guess that keeping the pilot at left was more of a minimal change subject when modifying the B(I).8 to the PR.9.

The brakes on the Canberra was a set of "fingers" being extended up and down from the wing. The can be seen on this pic:



It is somewhat unfair to say that the original airbrakes were ineffective - they worked brilliantly in landing situations when the issue is to modify the lift of the wing. However, in CAS/intruder flying, the main issue is to be able to manouver violently but controlled at high speeds and low altitudes and the "fingers" didn't really suffice in controlling sudden wishes to bleed off airspeed. To improve that situation, Martin added large "barn door brakes" on the sides of the rear fuselage, operating them in conjunction with the fingers. It did give handling improvements but it should be noted that the B(I).8 did work very well in a similar role as the B-57B but with only the finger brakes.

The bomb bay doors as such wasn't a problem by themselves being  a bog standard solution very similar to much later designs, f.i the B-52. However, Martin had already designed a rotating bomb door, very similar to the solution on later Buccaneer but without the fuel tank option, and as that door lessened the drag when on final bomb run, a higher airspeed could be maintained without losing accuracy - or higher accuracy could be obtained by keeping the original Canberra bomb run airspeed. Clearly a better solution already being readily available - but the original Canberra setup did work and was not flawed in any way.

All above said - the ultimate tactical Canberra was very likely the B-57G even if I personally, being somewhat inclined to prefer European engineering, would have liked to say something else. My personal take in the issue - from a whif perspective - is starting from the PR.9, thinning the wings, stabilisators and fin somewhat to reduce drag (otherwise an issue on the broad chord PR.9 wing) but then clipping the wings substantially, basically all the way to the ailerons. The shorter wing span in combination with the broader chord should give a wing with at least the same lift as the B(I).8/B-57G but with a somewhat better roll rate. naturally, I'd carry over the extensive armament pylon package from the B-57 as well as the cannon installation in the outer wing. Then guns themselves, however, would naturally have been 30mm ADEN:s.
Also, I'd keep over the 200-series Avon engine from the PR.9, possibly however switching to an Avon 207 rather than the original 206 as the 207 worked very well in the Hunter FGA.9 in similar roles and also was slightly punchier at lower altitudes.
In order to stay firmly british, naturally I'd keep the cockpit arrangements with the nav/bombardier still buried in the nose coal hoe from the PR.9. However, rather than cameras in the swinging nose section, I'd install a proper dual mode radar set, combining TFR and target search-and-track and also an A-6 TRAM-ball (which, in a whif world, very well could have been developed in UK just for this "Super Canberra"), perhaps at a later stage combined with a fixed FLIR system allowing the nav/bombardier to "own" the TRAM regardless of pilot visual needs.

Ah, well, that was firmly offtopic..

[rickshaw]

Interesting points, Pellson.   I'll just add that the problem with the Canberra's bomb bay doors was that they caused considerable drag when opened.  In fact according to some pilots, they were better at being air brakes than the "fingers" were!  They also couldn't be opened at higher speeds, which in particular caused problems with the LABS bombing system.   The Martin rotary bomb bay on the otherhand had fewer limitations.

The "fingers" were considered marginal, at best according to some accounts but as you note, the RAF stuck with them throughout the aircraft's career.

[Weaver]

My understanding is that the Canberra B(I).8 pilot sat right at the back of the cockpit area with the navigator sat sideways in front of him, the latter moving to the nose for bomb-aiming. I don't think he had access to an ejection seat. In the PR.9, the nav sat facing forward with the nose full of his control panel rather than bomb-aiming equipment & window, so he could have an ejection seat (you can see the outlined blow-off panel on the nose of PR.9s ahead of the pilot's windscreen).

[Pellson]

Brian, "airbrakes" have most often two functions:
1: to disturb airflow over the wing in order to increase sink rate in a controlled way and
2: to physically "brake" the aircraft in mid-air, i.e. rapidly bleed off speed.

The fingers worked according to first hand information from Canberra pilots very well in function 1 but not at all as well in function 2 above. As you said, for 2 you could use the bomb bay door (subject to speed limitations, of course).

My understanding is that the Canberra B(I).8 pilot sat right at the back of the cockpit area with the navigator sat sideways in front of him, the latter moving to the nose for bomb-aiming. I don't think he had access to an ejection seat. In the PR.9, the nav sat facing forward with the nose full of his control panel rather than bomb-aiming equipment & window, so he could have an ejection seat (you can see the outlined blow-off panel on the nose of PR.9s ahead of the pilot's windscreen).

Basically all true. The nav/bombardier in the B(I).8 sat on a fixed (no-bang) seat right by the side of the pilot, against the same pressure bulkhead but lower in the airframe. if things went solidly tits up, he was supposed to crawl forward and jump through the entrance hatch while the pilot always had a bang seat. Not entirely satisfactory in relation to the normal operating altitude..
When navigating, the nav/bombardier could crawl forward under his instrument panel to a mid-nose station where he had a folding seat and sat by a smallish table facing left. He could also crawl all the way up front to lie in a prone position in the glass nose, that however not normally being used operationally as the tactical behaviour of the B(I).8 was to leave the aiming to the pilot, using a sight unit on his dashboard.

As for Canberras and bang seats, there is, somewhere on the internet, a very interesting tale of a systems operator who when his Canberra B2 (I think) cartwheeled on landing, got more or less accidentally ejected and survived despite the seat being firmly not zero/zero in any way, due to the fact that the upward motion was counteracted by a downward motion in the cartwheeling sequnce, resulting in the lucky chap basically being dropped off on the lawn as the machine disintegrated. A bit like that flight attendant in the haystack, you know..

...and now we've REALLY gone offtopic..

[KJ_Lesnick]

rickshaw

Kendra/Robynn, Jon has already answered your question about the term "intruder".

And I was simply responding to his statement.

I am unsure why you claim the Canberra has a "weird cockpit setup".

Mostly it being off to the side instead of on the centerline

Interesting points, Pellson.   I'll just add that the problem with the Canberra's bomb bay doors was that they caused considerable drag when opened.  In fact according to some pilots, they were better at being air brakes than the "fingers" were!

I'm wondering if any pilots just opened the bomb-bay doors as a braking solution...


sandiego89

Douglas F3D Skynight meets most of your criteria.

True, as did the F-89 actually...

A major conflict with your desires in that time frame is with avionics.  You express desire for a small A-4 sized aircraft, but want all weather avionics.  Those vacuum tube days required large avionics bays, and large radar dish sizes, and a second crewmember to turn all those knobs- all driving up the size of the aircraft.

That is a good point.  I'd already assumed there would be a second crew-member.

How big did the radar have to be for the job and how much space did the avionics bay take-up?  I'm just curious if the aircraft's size could be kept somewhere between the A-4 and the B-57


Pellson

It is somewhat unfair to say that the original airbrakes were ineffective - they worked brilliantly in landing situations when the issue is to modify the lift of the wing. However, in CAS/intruder flying, the main issue is to be able to manouver violently but controlled at high speeds and low altitudes and the "fingers" didn't really suffice in controlling sudden wishes to bleed off airspeed. To improve that situation, Martin added large "barn door brakes" on the sides of the rear fuselage, operating them in conjunction with the fingers.

They had two different types of brakes?

Martin had already designed a rotating bomb door, very similar to the solution on later Buccaneer but without the fuel tank option, and as that door lessened the drag when on final bomb run, a higher airspeed could be maintained without losing accuracy - or higher accuracy could be obtained by keeping the original Canberra bomb run airspeed.

The accuracy was done by having the bombs in the airflow?


Everybody

What was the requirement for the range?

[Weaver]

Basically all true. The nav/bombardier in the B(I).8 sat on a fixed (no-bang) seat right by the side of the pilot, against the same pressure bulkhead but lower in the airframe. if things went solidly tits up, he was supposed to crawl forward and jump through the entrance hatch while the pilot always had a bang seat. Not entirely satisfactory in relation to the normal operating altitude..

Pretty poor really, considering that both back seaters in the B.2 had bang seats. You'd have thought from the example of the Sea Vixen that the nav's seat against the bulkhead could have been a bang seat thereby giving him a chance of getting out during take-off and landing at least...

[PR19_Kit]

Basically all true. The nav/bombardier in the B(I).8 sat on a fixed (no-bang) seat right by the side of the pilot, against the same pressure bulkhead but lower in the airframe. if things went solidly tits up, he was supposed to crawl forward and jump through the entrance hatch while the pilot always had a bang seat. Not entirely satisfactory in relation to the normal operating altitude..

Pretty poor really, considering that both back seaters in the B.2 had bang seats. You'd have thought from the example of the Sea Vixen that the nav's seat against the bulkhead could have been a bang seat thereby giving him a chance of getting out during take-off and landing at least...

I thought that too, and the Nav was next to the pilot just as the two rear crew members on the B2 and B6 were so there shouldn't have been a problem in getting out. Perhaps that was decided by the same gawp that decreed that the back seaters in V bombers were expendable.....

[Weaver]

Basically all true. The nav/bombardier in the B(I).8 sat on a fixed (no-bang) seat right by the side of the pilot, against the same pressure bulkhead but lower in the airframe. if things went solidly tits up, he was supposed to crawl forward and jump through the entrance hatch while the pilot always had a bang seat. Not entirely satisfactory in relation to the normal operating altitude..

Pretty poor really, considering that both back seaters in the B.2 had bang seats. You'd have thought from the example of the Sea Vixen that the nav's seat against the bulkhead could have been a bang seat thereby giving him a chance of getting out during take-off and landing at least...

I thought that too, and the Nav was next to the pilot just as the two rear crew members on the B2 and B6 were so there shouldn't have been a problem in getting out. Perhaps that was decided by the same gawp that decreed that the back seaters in V bombers were expendable.....

Well they wern't expendable, just cheap: Avro had a whole ejection system designed for them (seen it in the Woodford Heritage Centre), but the RAF/MoD decided it was too expensive....

[sandiego89]

rickshaw


sandiego89

Douglas F3D Skynight meets most of your criteria.

True, as did the F-89 actually...

A major conflict with your desires in that time frame is with avionics.  You express desire for a small A-4 sized aircraft, but want all weather avionics.  Those vacuum tube days required large avionics bays, and large radar dish sizes, and a second crewmember to turn all those knobs- all driving up the size of the aircraft.

That is a good point.  I'd already assumed there would be a second crew-member.

How big did the radar have to be for the job and how much space did the avionics bay take-up?  I'm just curious if the aircraft's size could be kept somewhere between the A-4 and the B-57

During your proposed time frame an air to ground radar and associated avionics bay would have been large.  Air to ground radars were still very new, as more compact multi-mode radars were still a decade or so away. A potential radar for your proposed aircraft would be the U.K. H2S, or the  US improved version as the H2X. http://en.wikipedia.org/wiki/H2X  One application for the H2X was to replace the belly turret on a Privateer with the the antenna, so that gives a rough size for just the antenna- around 24 inches, which may not sound like much, but with the dish and the support structure this really prevents something like this being in a slender nose like an A-4.  Remember small nosed aircraft like the A-4, F-5, Mirage etc have always had challenges incorporating a radar in their later versions.  The small radars on fighter aircraft, like the early Sabre, crusaders etc, were simplier gun laying and ranging radars and had a much smaller dish.  Air to ground radars require a larger antenna, usually a dish shaped.

The avionics to support such a radar require an avionics rack inside the fuselage.  Multiple cables, black boxes etc.  I do not have the exact cubic feet requirements, look up some aircraft cutaaways to give you ideas.  Think in the size of a few large suitcases.  Rather heavy also.   

The radar operator requires a seat and a display console. Usually inside the aircraft as early dispalys required dark areas to see the scope, or a hood. Again more size and weight.

Radar design is quite complex with different wavelengths, antenna shapes etc dictating what you need.  To summarize it, given your time frame and the desire for an all weather ground mapping radar you are going to end up with an larger aircraft- getting to a canberra sized pretty quickly. If you decide to forget the all weather ground mapping radar, you can get much smaller easily.  A tradeoff.

Just rying to keep it realisitc- hope this helps.  -Dave           

[Pellson]

Pellson

It is somewhat unfair to say that the original airbrakes were ineffective - they worked brilliantly in landing situations when the issue is to modify the lift of the wing. However, in CAS/intruder flying, the main issue is to be able to manouver violently but controlled at high speeds and low altitudes and the "fingers" didn't really suffice in controlling sudden wishes to bleed off airspeed. To improve that situation, Martin added large "barn door brakes" on the sides of the rear fuselage, operating them in conjunction with the fingers.

They had two different types of brakes?

Yep. Hydraulically tied together so that they always operated together.

Martin had already designed a rotating bomb door, very similar to the solution on later Buccaneer but without the fuel tank option, and as that door lessened the drag when on final bomb run, a higher airspeed could be maintained without losing accuracy - or higher accuracy could be obtained by keeping the original Canberra bomb run airspeed.

The accuracy was done by having the bombs in the airflow?

Nah, mostly by the reduced vibration, bumpiness and increased controllability resulting from the lesser drag and less violent turbulence following from the less deep hole in the belly with the rotating bomb door.

[KJ_Lesnick]

sandiego89

You make very good points so I have some questions based around three questions

I: Range & Payload

A. The specification called for a 4,000 pound payload to be carried 475 nm: Did this presume a heavier payload carried further, or a lighter payload carried greater distances?

II: Radar

A.) The SCR-720 was 29 inches in diameter correct?
B.) What radar was to be used by the XB-51 and B-57?

[sandiego89]

sandiego89

You make very good points so I have some questions based around three questions

I: Range & Payload

A. The specification called for a 4,000 pound payload to be carried 475 nm: Did this presume a heavier payload carried further, or a lighter payload carried greater distances?

II: Radar

A.) The SCR-720 was 29 inches in diameter correct?
B.) What radar was to be used by the XB-51 and B-57?

Sorry, I do not have all those answers on the top of my head, but you should be able to find those with a little reasearch.  Range/payload requirements often had multiple variables: heavy load a shorter range, and a lighter load a longer range. 

[KJ_Lesnick]

sandiego89

Sorry, I do not have all those answers on the top of my head, but you should be able to find those with a little reasearch.

Actually that was with research...

Range/payload requirements often had multiple variables: heavy load a shorter range, and a lighter load a longer range.

So 475 with 4,000 was the maximum needed?