The engine driven pump (so far as I can determine at this stage) was the correct one for the engine but I don't know how much extra fuel it was physically capable of delivering. It remains untouched until I can find a suitable rebuild facility to run it up and measure its output. We can accurately measure the fuel capacity of the three tanks and the fuel lines plus duration of the runs can be fairly well established from the recording of the radio traffic though we can't say how long the engine was idling before the first recorded transmission.
Now here's a curve ball for you. The system wasn't gravity at all fed. Fuel was siphoned from the main tank into a swirl pot with its own boost pump and from there into a second, auxilliary tank in the bottom of the hull - again with a boost pump - then into the engine. Because all the breather plumbing was thin-wall steel pipe it's long gone so we can't be sure how it was set up.
Both boost pumps were cobbled into the same electrical supply. The boat was set up in 66 with only the lower pump but when the second was added in place of the fuel filter they just lashed it into the same relay. K7 had no on board power generating equipment and so relied on a pair of batteries - condition unknown, as well as their state of charge.
It's entirely possible that the fuel system is the culprit.
Bill - your last point regarding pump power and battery condition started me thinking as to how we might estimate the former and any potential effects on battery voltage.
The method I've used to assess this might seem obscure - and possibly tenuous - but here goes (for those not interested in technicalities, please go to the next post!)
The Orpheus had a specific fuel consumption (s.f.c.) of 1.06 (i.e. 1lb of thrust for 1 hour required 1.06lb of fuel). The Orpheus was running at max. + 10% = 5225lb.
Fuel consumption per minute was therefore 5225x1.06/60 = 92.3 lb/min i.e. 11.5 gall/min (assuming 1 gall. kerosene = 8lb).
I then took a look at my model jet engines (see below) and did the same calculation. Interestingly, their s.f.c. is not that far removed from the Orpheus being 1.35. Each engine produces 38lb max. thrust and to achieve this requires a pump power of 80 Watts.
Armed with this data it was then possible to calculate the total pump power required by the Orpheus on the basis of the relative thrusts corrected by the relative s.f.c's multiplied by 80.
Total Pump Power = (5225/38) x (1.06/1.35) x 80 = 8640W or 8.64kW. If the batteries were connected in series to give 2 x 12V = 24V (consistent with aero' systems at that time on 24V), the current drain would be 8640/24 = 360A.
Now in all this I'm making a pretty coarse assumption that the relative efficiencies of the Orpheus' pump(s) and my small ones are the same (??) but it does suggest that there are some mighty big currents being taken from those batteries. It also must have been some relay that was switching it --------!
So to the effects on Jan 4th. If, indeed, flame-out occurred at the end of the first run this could have been due to loading/partial discharge of the batteries reducing voltage, or, the relay could have dropped out altogether due to low voltage, thus terminating fuel flow.
I am sure you are also aware that there is an in-between situation in relay operation where a making/braking
oscillation can occur caused by the battery voltage being loaded, the relay breaks, the voltage recovers, the relay makes - and so on. This would not necessarily have caused the engine to flame-out, but would certainly have reduced fuel flow and thereby, engine thrust --------.
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