Two questions on trim settings (fuel & elevator)

[johncantwell]

G’day again guys,

First off, I am making real progress with the Vanguard and have fallen in love with its looks (the white/silver Demonstrator livery is delightful -- nice one, Garry) and her quirky but fascinating operation (brilliant panel, Fraser). My engine start-up is now smooth (after some stuffing about initially) and I’ve even down to details like fuel trim settings during the climb according to the trim chart. Still working on the Autopilot, but I’ll get there. It’s all good.
Now, two trim related questions (fuel and elevator):

(1) Step 13 of the Start checklist in the Manual, referring to HP Cocks, it says “ 500 LP RPM – MOVE TO INITIAL OPEN POSITION”. OK, I understand that this is a position somewhere between 0-100 percent, and I notice that the RAPID START cheat sets the HP cocks around 34 percent initially, but is there an optimum setting or one I calculate? Does it matter? The engine starts whether I set it on 30 or 80 or any number in between.

(2) The TAXI checklist calls for setting the ELEVATOR TRIM. I can’t find where I calculate this and by experiment found that somewhere around + 2.5 produces a reasonable outcome. Can anyone point me to the appropriate table or suggest suitable weight/trim settings?

Oh, I just thought of one more question:
What is the appropriate ACCELERATION HEIGHT (Ha)? I used 500 ft but is there a standard or calculate Ha value?

Any assistance would be greatly appreciated. I haven’t enjoyed learning a new aircraft (payware included) for a very long time.

Cheers
John
Canberra/Australia

[DaveB]

Hi John

Chuffed that you're enjoying one of Vickers finest ;-) I'll try and answer your questions as well as I can..

Ha.. I think what you're using (500ft) is as good as anything. I have the Merchantman checklist in front of me and while it mentions (After Takeoff) Ha.. flaps - Climb.. TGT's - Check.. it doesn't actually state what value Ha is! The next milestone would be 'Climb at 1500ft QFE' where you'd expect flaps to be UP (or before/as you hit 200kts). ;-)

Fuel trim and HP cocks..
On the real girl, you'd note the ambient temp airport altitude and take your trim setting from the chart kept on the flightdeck. I think Fraser has gone for 35% on quick start to put it into the correct ballpark. As long as your tgt's stay within specified boundaries.. you're ok ;-)

Elevator trim would depend on weight (and I suppose runway length) and I can't remember how Fraser set this up. It should go 'blue' tick on the interactive checklist when it's 'in the zone'.

A lot of answer there and looking at it, I'm not sure how much help it will have been I'm dashing against the clock here so if there is something still you're not sure of or happy with.. give us another shout and I'll get back to this when I can (or Fraser will jump in with an explanation of how he programmed the gauges) ;-)

ATB

DaveB :tab:

[Viscount Cornbank]

Hi John,

Dave had largely answered your queries, just to add to that, Ha is generally 400ft AAL ( 400ft QFE ), unless obstacle clearance is critical.

The 34% fuel trim position corresponds basically to the minimum fuel when the cock is opened. It goes right down to zero trim on the real one but I couldn't squeeze all the numbers in legibly and the chart never calls for a figure below that if I remember rightly :think:

As Dave says, when the tick is blue on the checklist the trim is correctly set, it varies with weight ;-)

cheers

Fraser

[DaveB]

Tks for that Fraser

ATB

DaveB :tab:

[johncantwell]

Great, thanks for the replies Dave and Fraser. I'm enjoying a bit of leave from work right now so I intend to give the lovely lady lots of attention today.

Cheers
John