Canberra GR.22

[Hawkeye]

I think you should consider placing your "extra" engines inside of the existing ones. Get those engines too far out and the chances of loss of control because of asymmetrical thrust during engine failure becomes an issue. The alternative would be to increase the size or cord of the tail/rudder. A beefier main gear is also prudent, maybe add a second wheel to each strut. Maybe a tandem affair like used on the TSR 2, otherwise you'll have to bulge the upper wing to expand the landing gear well for side by side wheels.

Paint scheme? Over all white maybe?

[AeroplaneDriver]

As close the centerline as those extra engines are I wouldnt think there would be a control problem with a single failure.  Loning both on one side wold obviously be more of an issue, but as Hawk says, a bit bigger rudder should make everything work out.

But then again, you know all of this Simon, so I'll just shut up now.   

[John Howling Mouse]

How do you like that Olfa circle cutter, Betty?  Been thinking about getting one.  Is it pretty good in styrene too (up to about 4mm thick)?

[SimonR]

How do you like that Olfa circle cutter, Alan?  Been thinking about getting one.  Is it pretty good in styrene too (up to about 4mm thick)?

Alan? The Olfa cutter is very good - it's the only practical tool for cutting circles. It would certainly cut 4mm styrene but it would take patience to get a good result. But kitbashing teaches patience if nothing else...

[SimonR]

I think you should consider placing your "extra" engines inside of the existing ones. Get those engines too far out and the chances of loss of control because of asymmetrical thrust during engine failure becomes an issue. The alternative would be to increase the size or cord of the tail/rudder. A beefier main gear is also prudent, maybe add a second wheel to each strut. Maybe a tandem affair like used on the TSR 2, otherwise you'll have to bulge the upper wing to expand the landing gear well for side by side wheels.

Paint scheme? Over all white maybe?

I like your vertical stab chord and gear suggestions, I'll see if I have time...

The four engined Canberra would actually be better in an asymmetric thrust condition than the two engined original. The single engine handling of the Canberra was very difficult as, in order to retain rudder authority in the yaw axis, thrust on the remaining good engine was limited to 50% - giving 25% of the usual available thrust. Obviously, in low speed or heavy weight regimes this is usually a death sentence - the IAF has lost a lot of Canberras this way.

However, in my four engine version we'd still have a full operational engine on the side with the failed engine. That means we'd need a smaller thrust reduction on the other two engines to maintain rudder authority than the two engined version.

Here's a four engine Canberra with engine 3 out:

1 2 3 4

O O X O

Say the Avon RA.7 has 7,400lbf and the maximum thrust asymmetry the airframe can tolerate is 3,200lbf (working from the 50% throttle reduction SOP in the real Canberra). In the four engine version we still have 7,400 from the remaining good engine (4) on that side. On the other side with the two good engines (1 & 2) we have 14,800. But if we want a maximum asymmetry of 3,200lbf then we want about 10,600lbf from 1 & 2 combined - about 70% thrust on 1 & 2 if we keep 4 on 100%. The total thrust available in a 3 engine configuration is 18,000lbf (7,400lbf from 4 at 100% and 10,600lbf from 1 & 2 combined at 70%). This is about 60% of the normal thrust available; far better than the 25% available in the original 2 engine variant.

Colour scheme will be all over Desert Pink I think and Op. Telic markings.

[Weaver]

Facinating build Simon - looks really promising.


Another problem with mounting the extra engines further inboard would be jetwash interaction with the tailplanes.

[John Howling Mouse]

How do you like that Olfa circle cutter, Alan?  Been thinking about getting one.  Is it pretty good in styrene too (up to about 4mm thick)?

Alan? The Olfa cutter is very good - it's the only practical tool for cutting circles. It would certainly cut 4mm styrene but it would take patience to get a good result. But kitbashing teaches patience if nothing else...

Oh, sorry, Betty, I went back and fixed the post.

[SimonR]

Filled, sanded and panel lines rescribed. The stretch is complete!

[Brian da Basher]

Nice work on the fuselage stretch, Simon! It almost looks like the kit came that way! I wish my mods looked so natural.

Brian da Basher

[SimonR]

A major project milestone - the fuselage is complete!



I've added extra Nimrod MRA.4 style vertical stabs and various bumps and antennae - satcom, ecm, lrmts, rwr, etc.

On to the wings and engines - this thing is turning out pretty big...

[Hawkeye]

One of the principle reasons the BAC Lighting was so successful was it engine configuration. Having the engines on the centerline one above the other meant that no asymmetrical thrust resulted when an engine lost power. Even an F-14 experiences a sudden yaw issue when an engine loses power...remember the crash in the movie "Top Gun"?

I was on a C-130 mission when we lost propeller pitch control, we immediately shut the offending engine down and flew the rest of the mission. The pilot had to adjust both power and trim to keep the aircraft from yawing into the bad engine. On landing it too presented a minor inconvenience when we had to reverse pitch to stop on the short field. Same thing occurred on a KC-135 returning from Thule Greenland. The pilot had a hell of a time keeping the aircraft from yawing into the dead #1 engine. What made it worse we were fighting a heavy cross wind.

Keeping the engines as close as possible to the center line of the airframe is preferred. Thats why aircraft such as the Beechcraft Starship had such good engine out performance, they were as close to the centerline as possible. The Nimrod with its engines buried in the wing roots had better asymmetrical handling in comparison to the 707.

Even light twins such as the Do-28 has its engines up forward and as close as possible. Having a greater distance between the source of the thrust and the rudder also helps negate asymmetrical forces through greater leverage.

Part of making a what-if design is more than just making it plausible, one has to make one believe it is in fact real. Love your "classic" multi tail fin setup found on many British designs.

Keep up the great work!

[Brian da Basher]

That's coming along great, Simon! I really like what you've done with the tail and the canopy and the very cool clear nose!

I'm really looking forward to your next update!

Brian da Basher

[SimonR]

That's coming along great, Simon! I really like what you've done with the tail and the canopy and the very cool clear nose!

Sorry to disappoint BdB but the nose will be getting painted - I presumed that by the time the Gentlemens' Bomber got to its 22nd iteration it would have some sort of terrain following radar in the nose to replace the sextant, astrolabe and vellum charts that were the normal Canberra nav kit.

The next job is to cut the wings up, I have to make 8 fairly large cuts and if I get any of them wrong the project is probably over...

[The Rat]

... and if I get any of them wrong the project is probably over...

Like Hell it is! You will see this project through Sir, or some very peeved gentlemen will visit you in the middle of the night! 

[SimonR]

Careful preparation needed for the wing cutting exercise.



Razor saws are fine up to a point but when you're ready for real precision and subtlety every kitbasher needs a 1500W table saw.



Fifteen very noisy and dusty minutes later all 8 cuts are done.



Here's the completed wing parts, I just need to assemble them now.