[simpits-tech] LVDT's Anyone ? (New Projects)

[Rick Davis]

----- Original Message ----- 
From: "Roy Coates" <roy at flightlab.liv.ac.uk>
To: "Simulator Cockpit Builder's List" <simpits-tech at simpits.org>
Sent: Wednesday, July 01, 2009 11:46 PM
Subject: Re: [simpits-tech] LVDT's Anyone ? (New Projects)


> On Wed, 1 Jul 2009, Rick Davis wrote:
>
>> One thing you may be able to clear up, because I've been told this but 
>> don't
>> know how much credence to apply to it, that the Concord actually flew by
>> shifting fuel (weight) from forward to rear, and right wing to left wing?
>> Any truth to that? Theory being that it flew so fast ailerons were
>> ineffective (or prone to being blown to bits) so when you turn the Yoke
>> left, pumps transfer fuel from the right wing to the left wing.
>>
>> Sounds bizaar, but possible?
>
>
> I think that would take far too long. However...
>
> "the centre of gravity (CoG) on Concorde it critical to it being able to
> maintain supersonic speeds and also fly successfully at low speeds. The
> centre of lift of the aircraft, when flying at Mach2, can move by some 6
> feet. On a traditional subsonic aircraft the control surfaces (or entire
> tailplane) would be moved to trim the aircraft correctly, but on Concorde
> this would be unacceptable due to the drag it would cause and also leave
> very little movement left to control the aircraft.
>
> The way the change in the centre of lift from the wings is trimmed out on
> Concorde is to compensate by moving the weight distribution, or CoG, by
> pumping fuel from the forward trim tanks to the rear trim tanks and vice
> versa. The trim tanks make up around 33 tons of fuel that can be moved
> around the aircraft. (the main tanks hold 95 tons).
>
> Before take off and during the acceleration through Mach1 to an eventual
> Mach 2, fuel is pumped out of the forward trim tanks to the rear trim
> tanks and the collector tanks in the wings. Around 20 tons of fuel is
> moved in the process and results in a rearward shift of the CoG by 6ft (2
> meters.)
>
> At the end of the Cruise during the deceleration fuel is pumped forward to
> the wing transfer and even the forward trim tanks is necessary thus moving
> the CofG forward again as the centre of lift moves reward. Once on the
> ground it is standard practice to then pump more fule into the forward
> trim tanks to correctly balance the aircraft, so it can be unloaded
> without any stability problems and the chance of it becoming a
> "tailsitter"
>
> The Movement of fuel also provides additional benefits at lower speeds: By
> making the aircraft rearward heavy during take off and landing, this
> causes the elevons control surfaces to move downwards to counteract this
> weight and in so doing so increases the camber of the wing generating more
> lift at slower speeds. Another feature is the ability to move fuel across
> the aircraft between tanks 1 and 4. This allows the aircraft roll trim to
> be set without having slightly different deflection on the elevons, which
> again adds drag and reduces performance.
>
> The full transfers on Concorde are carried out by the flight engineer from
> his fuel control panel. On Concorde this is one of the most important and
> time consuming jobs for the engineer. The panel allows the engineer to set
> up the transfers to be carried out automatically and stop when the
> relevant quantities of fuel have been moved to the correct tanks."

Well Mr. Coates,

I certainly found your Co"G" spot! (sorry)

That was a wonderful breif on the workings of that bird. Thank you. You 
should post that to Wikki. I guess what I heard was right (although lacking 
the detail)

Concorde was an incredible machine no doubt. I was also told it had 6 
computers, could fly on two, but if two went down it would just find the 
closest place to land in it's limited list of available airports.  I don't 
think the Pilots really had a lot of control over this aircraft. If there 
were no computers for example, you are dead. It wont fly that way except 
tumbling straight down. Basically an upper atmosphere missile with wings. 
The prep time to get this thing in the air is reported to be huge. I have 
seen pictures looking forward to the cabin. The station on the right is the 
fuel transfer module??? Looks like the bloody Space Shuttle! Maybe more room 
in the Space Shuttle.

I'll have to try it now. Got my interest piqued.

Paris to NY. Nonstop. (I hope)

:)

R