[Enthalpy]

Two airmen died fighting wild fires yesterday in Greece as their Canadair water bomber touched bush
  bbc around 0:20
Tribute to the heroes.

The record of these water bombers is disastrous. The job is perilous and these planes stone-old. Yesterday's CL-215 has piston engines in star arrangement like the super-Constellation had, before the Caravelle and Comet introduced more reliable jet engines. Some countries who bought the CL-215 and turboprop CL-415 have lost every second one, with two people on board every time. The planes aren't produced any more and have no equivalent presently.

I proposed a design, with remote control, water scooping in flight, water ejection to exit stalling, hydrogen fuel cells for day-long flight, and more, there
  scienceforums
A smaller company can live from selling 100-200 planes. Europe observes this need, worse every summer.

Meanwhile, can the Canadair CL-215 and CL-415 get a retrofit?

I believe it has hydraulic control surfaces, then a remote control must be feasible. When I proposed it for heavy equipment at Fukushima, it was done in very few days.

Water ejection at high pressure to the bottom rear lifts and accelerates the plane to exit stalling even near the ground, but only with water left. By the way, I don't see the control surfaces move during yesterday's crash, as if they or the pilot were out of function, and the collision with bush a mere consequence.

Scooping in flight brings less to the existing Canadair flying boats but would help much other designs used as water bombers.

Hydrogen tanks, fuel cells from the Toyota Mirai and electric motors would improve the CL-215 and CL-415's reliability, let them fly for a day, reduce the maintenance. A plane typically needs several mechanics hours per flight hour, a hydrogen car few days per year.

I'd replace all hydraulic actuators by electric ones for reliability and reduced maintenance. Maybe some certification administrations accept it more easily at an unmanned plane. The CL-215 and CL-415 would pioneer this evolution wanted at all airliners.

[Enthalpy]

Everyone knew it but me: De Havilland Canada will produce the DHC-515, follower of the CL-415. Indonesia and six European countries want 28 planes.

Pictures show a CL-415 for which DHC acquired the rights. DHC and newspapers tell "important upgrades increase the functionality and effectiveness" without details: replace the now unavailable components, or more?

Certification announced for 2025, first deliveries in 2026, tag 35Musd
  fr.wiki - dehavilland

[Enthalpy]

I suggested to eject the water by pressure like a water rocket to lift and accelerate the plane if stalling, and to eject the last water ton faster
  28 Nov 2010 - 23 Jun 2017 (on saposjoint, later on scienceforums)
Here I develop the forced water ejection for regular operation too, without stalling, for new plane designs and as a retrofit.

The relative air speed apparently disperses the water at dropping. Forced ejection with 42m/s component to the rear would avoid that, letting drop from higher faster safer overflight. It takes only 9bar in the water tanks, more in the air tanks: trivial with fiber composites. Spread over 2s, the acceleration is 0.6g, twice as much as a take-off, less than turbulence or a sharp turn. Done every time, it would prevent some stalls without human decision.

Begin with <42m/s rear component, end with >42m/s, then the water reaches a smaller zone from a longer ejection sequence. The vertical component can vary too.

Orientable nozzles achieve that, several fixed nozzles too. Hardware should regulate the speed and the throughput independently.

I suppose ejection to one side is too dangerous, but spreading to both sides symmetrically seems feasible. One common valve for symmetrical nozzles is software-proof. The pilot could orient safely the overflight of mountainous terrain, independently of the fire orientation.

In a refined and desirable version, a touchscreen displays the terrain and the flames (from visible, amplified light, infrared, radar, UV... fused imagers). The scooper-dropper operator draws a target zone in the last seconds, and software deduces what nozzles open when, in what direction and by how much.

I strongly advocate the remote control of water bombers. The touchscreen control needs fast transmissions then.

==========

As they serve less in Winter, some European water bomber could then be based in the southern hemisphere: Chile (summer), south Africa... Australia please check, it must be the rainy season then.

Marc Schaefer, aka Enthalpy

[Enthalpy]

Hydrogen and fuel cells fly a DHC-615 for 12h easily, in continuous firefighting operation. Successive remote control teams bring the endurance, one scooper-dropper operator manages several airplanes.

I keep the turbines' 2× 1 775kW, which take 32 cells from the Toyota Mirai weighing 1824kg, or 838kg more than the turbines.

Mean 2/3 (no reason) of the shaft power over 12h are 102GJ. At 98%×61% efficiency, this consumes 600 kmol H₂: 1210 kg plus as much for the tanks totaling 17.0 m³.

4 ellipsoids, D=1.6m L=3.34m, hoist the hydrogen. The nacelles are slightly slimmer than the two original ones for piston engines (which are inboard like the turbines) and are nicely profiled. The fuel cells spread to adjust the center-of-mass. Alas, the electric motors need gears hence maintenance to be lighter than gas turbines.

I spread the power over 4 propellers and motors since they're cheap. More propeller area improves the traction at low speed and also the lift by blowing the whole Fowler flap width; struts can reinforce the wing. It combats also flow separation at the outboard flapless leading edge. Redundancy improves, more so with (aluminium) electric cables between the nacelles.

Mass estimates may come some day. In Quechua, the past is visible hence in front, and the future is in the back.

Marc Schaefer, aka Enthalpy