[jhb] Re: Which Speed?
- From: "bones" <bones@xxxxxxx>
- To: <jhb@xxxxxxxxxxxxx>
- Date: Sun, 1 Jul 2007 17:17:13 +0100
If it is overweight with just full fuel and no payload then he's either got
fuel capacity wrong or the Max AUW.
bones
-----Original Message-----
From: jhb-bounce@xxxxxxxxxxxxx [mailto:jhb-bounce@xxxxxxxxxxxxx] On Behalf
Of Gerry Winskill
Sent: 01 July 2007 16:32
To: jhb@xxxxxxxxxxxxx
Subject: [jhb] Re: Which Speed?
That was the first and obvious route I tried to take. To my surprise the
FSX Payload Settins menu just has a single Staion 1 slot and that
contained a default value of zero. Which didn't leave much scope for
reduction. A check on a Default A321 shows it has a six slot variation
capabillity, with a Default total passenger load of 14340 lbs. At least
the A350 designer hasn't just used a default model, as many do.
Gerry Winskill
bones wrote:
>Surely it would have been better to reduce passenger payload? Or was
>the aircraft over MAUW with no pax on board?
>
>bones
>
>-----Original Message-----
>From: jhb-bounce@xxxxxxxxxxxxx [mailto:jhb-bounce@xxxxxxxxxxxxx] On
>Behalf Of Gerry Winskill
>Sent: 01 July 2007 13:50
>To: jhb@xxxxxxxxxxxxx
>Subject: [jhb] Re: Which Speed?
>
>
>Definitely!
>I've just made one change to the aircraft.cfg. If full fuel loaded it
>exceeds MTOW, so I've reduced the centre tank capacity to correct.
>
>Gerry Winskill
>
>Alex Barrett wrote:
>
>
>
>>Gerry,
>>
>>I was always taught that a general figure for Vr would be 1.1 x the
>>aircrafts stall speed with flaps retracted.
>>
>>I actually downloaded the A350 yesterday and have started doing a
>>repaint for it, but haven't yet flown it. In your opinion is it a
>>"goer" as they say?
>>
>>Alex
>>
>>
>>Gerry Winskill wrote:
>>
>>
>>
>>>Having decided not to make assumptions about Vr, I ran a series of
>>>tests, at max and minimum takeoff weights, to find the takeoff speeds
>>>at the various permissable flap settings. I ran the tests hands off,
>>>with elevators trimmed up at 60%. I've got decent rpeatabillity,
>>>so..... I know it's nowhere as simple as a linear relationship but is
>>>there a reasonable difference I can apply to the takeoff speeds, to
>>>get to Vr?
>>>
>>>V1 and V2 are not, I guess, capable of being arrived at by rule of
>>>thumb.
>>>
>>>Gerry Winskill
>>>
>>>Gerry Winskill wrote:
>>>
>>>
>>>
>>>>A couple of days ago I downloaded the FSX version of the wide bodied
>>>>Airbus A350. It looks good and flies well.
>>>>
>>>>One advantage of the Airbus familly, to users of Fsim, is that
>>>>commonality of panels etc is a real aircraft feature. That left me
>>>>needing to modify the Vspeed gauge, to reflect the A350's weights
>>>>and V numbers. I've not managed to unearth any V number data but
>>>>weights and performance are available, from the Confidential sale
>>>>contract conditions that have found their way onto the Net..
>>>>
>>>>For Vr I'm assuming that the numbers won't be far off those for the
>>>>rest of the familly.
>>>>
>>>>Producing Vref data should be straightforward, since all I have to
>>>>do is determine the dirty stall speed, at the same altitude and with
>>>>zero wind, for a set of All Up Weights. Only it wasn't
>>>>straightforward. The aircraft.cfg gives the dirty stall speed as 124
>>>>kias, without reference to any weight. In fact there seems to be no
>>>>Aircraft.cfg facillity for varying stall speed with weight.
>>>>
>>>>The difference between the stall speeds I determined and the
>>>>Aircraft.cfg figure were big, to enormous! At Max Permissable
>>>>Landing Weight of 400,000 lbs it stalled at an indicated 99 kias,
>>>>with the Stall Warning following a few knots below that. At the
>>>>bottom end of the weights, with just the minimum permissable fuel
>>>>reserves, it stalled at 80 kias.
>>>>
>>>>As if that isn't bad enough there was a discrepancy between the AIS
>>>>/ Map indicated speeds and the Ground Speed recorded in my Checks
>>>>gauge. When ASI read 99 the GS was 110. With ASI at 80, GS was 88.
>>>>
>>>>Where does that leave me? It seems reasonable to take the actual
>>>>stall speeds recorded, as the route to calculating the Vref figures
>>>>for the simulated aircraft, but should I use the ASI or the higher
>>>>GS figures?
>>>>
>>>>In passing, the figures for dirty stall speed in most of the
>>>>aircraft I fly seem to be higher than the actual speed at which the
>>>>stall occurs. Which explains why I can seldom hold off enough to get
>>>>the Stall Warning klaxon to sound, when landing. Which makes it seem
>>>>likely that the actual stall speed data is held somewhere other than
>>>>the Aircraft.cfg. The fact that there is an actual variation of
>>>>stall speed with weight seems to bear this out, since that ain't
>>>>possible from the data held i the Aircraft.cfg. This is a serious
>>>>limitation of FSX and its predecessors, since lapses of
>>>>concentration allowing the speed to fall to the stall don't produce
>>>>the wake up effects of a real life lapse!
>>>>
>>>>Gerry Winskill
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>--
>>Alex Barrett
>>Turbine Sound Studios
>>(+44) 0121 288 3195
>>alex@xxxxxxxxxxxxxxxxxxxxxxx http://www.turbinesoundstudios.com
>>
>>
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