(No error) Both Wobble pump and electrical fuel pump ?

[fjacobsen]

The DCS has both the wobble pump on the right side and an electrical fuel pump oprated by a switch on the left side under the pitch trim wheel.

 

Shouldn´t it have been only either the wobble pump or the electrical pump ?

 

Quote from RL manual:

 

4

Fuel pumps

.—On Bendix-Stromberg carburettor installations an electric booster pump, operated by a switch on the left-hand

side of the cockpit, is fitted in the lower main tank. On early aircraft this pump is not fitted, but a hand wobble pump is

provided instead, just forward of the remote contactor.

[fjacobsen]

Anyone ?

 

According to all the docs I have been bale to find, the woble pump where on the early mk IX, whereas the electrical pump on later mk IX's - never both !

[Krupi]

That is what I have read as well :huh:

[blue_six]

I thought the same – surely it would have one or the other, but not both. Turns out I was wrong. Goblin researched this a while back, drawing upon the Monforton Spitfire e-book mentioned here: https://forums.eagle.ru/showthread.php?t=176679&highlight=ebook&page=9. It turns out all three configurations are possible. Here's what he found, quoted from Spitfire pilot’s notes, 3rd edition, dated September 1946, Air Pub 1565J, P & L—P.N.

 

 

“On early a/c with Bendix-Stromberg carburettor installation where no electric booster fuel pump was fitted, a hand operated wobble pump is provided to ensure good fuel flow is established when switching between the main fuel tank and the auxiliary slipper (drop) tank and back again. Later on when electric fuel pumps were installed, the wobble pump was retained as a backup and to save the batteries during engine start up. Late production a/c relied on the electric fuel pumps alone and did not have this pump installed."

[Krupi]

Awesome, embarrassingly I have that book and don't recall reading it :doh::lol:

 

So I guess Mk XVI didn't have the wobble pump. :D

Edited December 18, 2016 by Krupi

[fjacobsen]

Super research :)

[Roblex]

I am still a bit uncertain about when the fuel pump should be used. The official DCS training says to make sure the fuel pump is turned off when starting the engine. Chucks unofficial manual says to turn on the fuel pump above 15K. The actual RAF manual tells you to turn on the fuel pump during the pre-start checks.

 

Is there a reason why I should not turn on the fuel pump while starting the engine? I read something somewhere about avoiding the fuel pump flattening the battery which makes some sense but once the engine is running does it do any harm to turn on the fuel pump and leave it on?

[Sokol1_br]

PN - pag 18 - right - say this:

 

(iii) Use of the booster pump(s)

(a) The main tanks booster pump should be switched ON for take-off and landing and at all times when these tanks are in use in flight.

(b) The rear fuselage tanks... (Not applicable in game).

 

PN - Pg 19 - right

 

"(iii) Switch ON the main tanks booster pump for 30 seconds (or operate the hand wobble pump for that period) then switch it OFF and set the idle cut-off control forward to the RUN position"

 

PN _ pag 20 - left

 

"(viii) Check that the fuel pressure warning light does not come on then switch ON the main tanks booster pump (if fitted).

Edited December 22, 2016 by Sokol1_br

[blue_six]

Hi Roblex, the confusion here is traceable back to some loose terminology in the DCS Flight Manual. When the FM says to have the "fuel boost valve" turned OFF, what they are actually referring to is the fuel tank pressure cock, found below the instrument panel on the right hand side. They are not talking about the fuel boost pump. As Sokol1_br notes, the fuel boost pump can be switched ON briefly instead of using the wobble pump during the start-up sequence, but must be switched OFF again before start-up. Once the engine is running and adequate fuel pressure is confirmed, the boost pump should be switched ON again, and left on for the remainder of the flight. Again, the FM is weak in this regard.

Edited December 22, 2016 by blue_six
Said PM, meant FM

[Andy1966]

Hi All,

I'll ask my question here as it fuel system related. I'm not really clear on the function of the fuel tank pressure cock. Is it to pressurize the slipper? (which we don't have yet, but is coming), or the internal tanks? is it boost pressure? I've read the manual but might have missed it. I'm getting to the point I'm burning a full fuel load now and I was just wondering.

thanks

[blue_six]

In its description of the fuel system, the RAF Pilot's Notes for the aircraft indicate that the "blister" auxiliary fuel tanks feed the engine direct, rather than being plumbed through the two main tanks. The two main tanks, just ahead of the cockpit, can be pressurized at altitude if needed. This is controlled by the fuel tank pressure cock. The source of the pressure is the oil separator on the aircraft's vacuum system.

[Pilot909]

honestly i always start up using the electrical pump. WAY WAY faster.

[Sokol1_br]

Ki-Gass primer require only 2 pumps (ambient temp 20C).

 

Propeller Pitch lever and Carburator Air Intake can be leaved untouched that don't impedes start engine, taxi and take-off.

 

BTW - I am not saying that this is wrong, just that not use then don't has collateral effect - unless maybe for "P.N. followers" . :D

Edited December 24, 2016 by Sokol1_br