Print

[Renaud Dudon]

I think you're absolutely right. The E2b engine was fitted on a very large number of aircraft, so it seems logical that each manufacturer had to adapt its accessories.

The Grand Raid PL8 undoubtedly needed an additional water supply, which required some adaptation by the Levasseur workshops. And you're right that this builder was more of a craftsman than an assembly-line manufacturer. That's why it's so difficult to obtain standard data for this aircraft builder. For an example, you may have read my topic on the PL8's alferium propeller...

From memory, it seems to me that the manual only recommends the position of a possible feeder.

[Ric Gillespie]

From memory, it seems to me that the manual only recommends the position of a possible feeder.

The feeder has to be on top of the engine and the filler port for the water reservoir has to be at the highest point, which is where we see it in the photos.

[Renaud Dudon]

I would be interested to know what it says about the cooling system, especially if there is reference to a "nurse tank".

D'accord Ric, i will see if i could find some free time this week end to find this kind of informations if mentioned ! 

[Renaud Dudon]

Hello Ric,

I've started translating the pages about the cooling system. There are some interesting data. I hope to make progress by the end of the week.

As for what interests you most, I've already attached the interesting part:

page 36:

“No high point in the piping installation without possible release of air and steam (on the ground, in ascent or in horizontal flight).

The radiator (or feeder) must be loaded on top of the cylinders, both in climbing and horizontal flight.

Water outlet pipes with a minimum internal diameter of 34 mm must run upwards to the radiator (or feeder) in both climb and horizontal flight. (...)”

This passage tells us that it was not unusual to proceed with a water tank on top of the cylinders ("nourrice"), as the cold and hot water stream pipes had to be placed and routed in a way that favored fluid dynamics, circulation and the evacuation of steam in the event of overheating.

I was also able to check that the capacity of the water jackets was 19 liters for a total of 26 liters including the piping (not counting the radiators? I don't know for sure...).

A comment in the manual also states that in the event of a water shortage, the operating time without abnormal overheating is only a few minutes...

In your opinion, what is the capacity of the 'feeder' on the cylinder tops ?  Judging by the proportions, I'd say between 120 and 140 liters.

LTM

[Ric Gillespie]

Thanks Renaud.  This is very useful.

“No high point in the piping installation without possible release of air and steam (on the ground, in ascent or in horizontal flight).

The radiator (or feeder) must be loaded on top of the cylinders, both in climbing and horizontal flight.

Water outlet pipes with a minimum internal diameter of 34 mm must run upwards to the radiator (or feeder) in both climb and horizontal flight. (...)”

This passage tells us that it was not unusual to proceed with a water tank on top of the cylinders ("nourrice"), as the cold and hot water stream pipes had to be placed and routed in a way that favored fluid dynamics, circulation and the evacuation of steam in the event of overheating.

Agreed.

I was also able to check that the capacity of the water jackets was 19 liters for a total of 26 liters including the piping (not counting the radiators? I don't know for sure...).

A comment in the manual also states that in the event of a water shortage, the operating time without abnormal overheating is only a few minutes...

The question is, in the case of l'Oiseau Blanc, how long is a few minutes? That logically depends on the power setting (how much heat are the cylinders generating?); outside air temperature (the colder the better) and, primarily, how fast it's losing coolant.  Witnesses in the town of St. Mary's saw the plane "on fire" (trailing steam mistaken for smoke) headed west across St. Mary's Bay and last seen in the vicinity of Red Head on the eastern coast of the Cape Shore peninsula.  That's a distance of 14 miles.  From Red Head to Gull Pond is 8 miles, for a total of 22 miles.  At l'Oiseau Blanc's cruising speed of 100 mph, that would take 13 minutes – call it 15 minutes with a headwind.   

In your opinion, what is the capacity of the 'feeder' on the cylinder tops ?  Judging by the proportions, I'd say between 120 and 140 liters.

It's an important point.  The trail of steam suggests the pipe delivering hot water to one of the radiators burst. With one of the radiators still working, the cylinders are still being cooled to some degree until the coolant is exhausted.  How fast coolant is lost depends on the water pressure and the diameter of the failed pipe.  Once the water in the reservoir is depleted the engine will overheat until it eventually seizes.  We don't have enough data to quantify the time between the failure of the pipe and engine seizure, so we're left with a gut guess.  Is 15 minutes a reasonable ?

[Renaud Dudon]

Ric, It's a coincidence, but when my father and I looked at the engine manual and I asked him about it, he said 15-20 minutes, at most, at low revs.

The optimum revs with the propeller and 'réducteur' is around 1230 rpm for an engine rpm of 1800 max. We can expect 650 revs at reduced throttle (idle is around 400 from what I understand).


Optimum oil operating temperature is 70°C. Without a water [edit: high] pressurization system, water overheating and boiling can be estimated at 100-110°C. 30°C margin is not much.

How long? My instinct is that 15 minutes is achievable. In any case, if I'd been Nungesser, I'd have tried to reduce the revolutions, lengthen my descent, steady, as far as i could and bring my bird to the ground as soon as possible.

Edit: but you've got the point: that is gut guess... no scientific demonstration here...