Hydraulic accumulators withstand pressures up to 3000psi, however their volume is only 50 cubic inches. They are located in the aft stab bay.
I would recommend the hydraulic reservoirs. They could easily withstand pressures over 50 psi as they are normally pressurised with bleed air. They are also fitted with an over pressure relief valve that goes off at 90psi. You could mount them directly above an open flame.
The left and right system reservoirs have volumes of 12.6 gallons and the centre system reservoir has a volume of 26 gallons. The left and right reservoirs are located in each respective engine pylon and the center one is in the right hand wheel well.
Ideal boilers for your steam engine.
Are there any hills or cliffs on your island? You could build a header tank to feed the boiler. Static pressure calculations determines each foot provides 0.43psi, therefore to supply 50psi you would require a header height of 116 feet.
Last edited by winglit; 24th Sep 2014 at 00:20.