jet flying boats

[steelpillow]

Was browsing this wonderful thread at Secret Projects:

http://www.secretprojects.co.uk/forum/index.php/topic,645.0.html

and I thought, how do you keep the sea spray out of the jet engine intakes? D'oh! Of course! Shield them with a canard foreplane!

So here's Fairey Aviation going back to its roots as a supplier of Naval aircraft, not long after its Delta 2 broke the world airspeed record at over 1,000 mph:

[ericr]

a lot of whiff potential, e.g. for a Rafale (M version, of course) 

[RAFF-35]

That could look really pretty in real plastic 

[Tophe]

Unusual and (so): nice!

[Joe C-P]

This would be interesting to see in a wind tunnel.

But whiffing cares nothing for physics, so build that baby! 

[steelpillow]

This would be interesting to see in a wind tunnel.

That is the best bit. Why do you think Fairey chose a delta foreplane? As the angle of attack increases, its airflow quickly becomes dominated by the classic delta-wing vortex pattern. Airflow approaching the inlets is actually held downwards by the inboard walls of the vortices and smooth flow in the central region of the foreplane is maintained. Only the outer sections get the full vortex treatment. Note how the inlets are positioned inboard of the vortex zone to maximise the benefit of this effect. The foreplane is in effect unstallable and smooth airflow to the engines is assured at all angles of attack. Check out the intake location on the Convair F2Y Sea Dart if you want to know where best to put it on a tailless delta.

The practical issue is that the foreplane needs to be high-mounted so that pushes the inlets even higher. An annoying thing for the average landplane but it plays neatly into the hands of the seaplane designer. Look at the competition in the Secret Projects discussion (you have to join to see the piccies), most have inlets in silly places where either spray will flood the engines or the timidly-swept wing will starve them at high AoA when they are needed most. But by the time anybody started putting canards in front of delta wings, Convair's Sea Dart was just a memory and the era of the jet flying boat long gone.

Except, of course, for an obscure Admiralty requirement addressed by Fairey. The idea was to deploy a flotilla of high-performance warplanes in defence of islands and other Commonwealth territories which had had their runways trashed. By dispersing them and their support bases around suitable harbours, the high vulnerability, high cost and leisurely deployability of a large capital aircraft carrier could be overcome.

The support bases were a key part part of the weapon system and were containerised for fast air-freight delivery. They could even be pushed out the back of a Hercy bird, air-dropped into the waters of the harbour so no runway would be needed.

Would have come in handy during the Falklands campaign.

[steelpillow]

 A later refinement included the conical leading edges which had been introduced on the Convair F-102 production version, F-106 and B-58, along with better area-ruling, modernised canopy. a 1ft fuselage stretch to increase fuel capacity also necessitating a redesigned and slightly taller fin, and an uprated Avon with larger-diameter afterburner nozzle.

The conical leading edge sits inside the Mach cone of the leading edge root and, rather surprisingly, actually improves lift/drag ratio in supersonic cruise leading to greater range. It also improves low-speed handling. In the UK this last aspect happens to infringe on a 1909 patent by J.W. Dunne (as do all Rogallo deltas too). I'd love to find out when that patent lapsed as, although Dunne's company was formally wound up in 1919, the patent was in his own name and he did occasionally dabble in aeronautics after that.

Oh, I nearly forgot - The revised Fairey Delta Seaplane: