Classic British Flight Sim

Well hello !

Tweak Aircraft for FSX...

http://www.tweakfs.com/store/product_in ... d1486c19ca

I'm thinking of getting this to see if I can remedy what I perceive as niggles and irritations in some recently purchased aircraft. For example, the well-liked ( by me anyway ) Virtavia Lincoln goes too fast at even moderate throttle ( as does their B-29, incidentally ) and also has a slight tail-down attitude at normal cruising speed. There are certain other aircraft that have trim problems as us recent Razbam customers have found out to our cost.

So...has anyone used this utility ?

Deafening silence....I think that's a grand total of....um...... zero so far, Paul.

At US$17, it must be worth a try?

Haven't used it, but it looks like there's a 30 day free demo. Let us know how you get on

I've never used this app before, but I just downloaded the demo. This is just my 2 cents on this but I think you'd be just as well off using Notepad and the FSX SDK. Here is a link to the FSX SDK. http://msdn.microsoft.com/en-us/library/cc526949.aspx
Below is a screenie of TweakFS in action. It shows you how to edit an entry but the little 'help' window only tells you (word for word) what is stated in the FSX SDK regarding the variable that you're wanting to edit. Hope this helps.

It helps very much, Brian. Thanks ! I was going to try it out today, but ended up doing other computery things. I really would like to get the Lincoln flying level - I'm sure its something to do with the C of G which, in the fuel and payload manager menu, appears to be way aft of where it should be.

Hi Paul

What the CoG is doing in the fuel/payload window may not tell the whole story. When you say 'flying level'.. what are you seeing happen? The tanks are all equidistant and the crew are there or thereabouts (though we know that small variations in crew placement can make models do odd things in FSX)

EDIT: Just had another quick look Paul. It seems directionally stable but flies with a 2deg nose up attitude. I honestly don't know how accurate that is (pitch) so it's impossible to comment. It does seem sensitive to trim.. perhaps too sensitive. It's difficult to get it to sit at a given altitude without changing RPM and/or throttle and even then, it's either up or down. The AP keeps it nailed but I tend not to use AP's on this type of aircraft. It seems impossible to 'fly out' that nose up attitude. The best I've seen is 1deg up before it overspeeds. 1deg is neither here nor there. I just flew this with full tanks but minus bomb load

ATB
DaveB

Dave, it seems the Lincoln always flies slightly tail down/nose up, even when it's at maximum speed ( 316 knots ! ), with the AP 'altitude hold' selected - in this case, 10,000 ft. The artificial horizon shows it to be flying slightly nose down ( as you would expect at that speed ) but the external model is slightly nose up. As you decrease speed towards the recommended 145 kts cruising speed, the nose-up attitude increases. Even when passing 200 Kts, with the bomb bay empty, the tail and mid-upper gunners AWOL and the bombardier's weight adjusted to 9000 lbs, it still flying nose up.

Any recommendations or thoughts would be appreciated.

EDIT: Just read your edit in the post above.

It's been a while since I've fiddled with this sort of thing but from memory.. the values needed to set the models cruise/altitude are set in the airfile. Values can be changed in the cfg to tweak this slightly but from experience, any fiddling in the cfg can have adverse affects at other areas of the flight envelope. If the airfile has been setup correctly, one might expect the aircraft to have maybe a 1deg nose-up attitude.. no more than 2 (I'd have thought) when flying at it's 'set' cruise speed and altitude. Cruise speeds are often quoted as GS rather than IAS so it's easy for the plot to go horribly wrong. I wouldn't expect Virtavia to make this sort of error though

EDIT: You could try adjusting the Cruise_Lift_Scalar Paul.. memory man strikes again

ATB
Dave

I've just been experimenting with my current WIP project as I was getting about 4° nose up in cruise, & the only way I've found so far is to alter the Cl vs AoA curve in the air file, this does then need a corresponding change to the Cm vs AoA curve. One then may also need to change the empty weight C of G position to then have sufficient trim for the various C of G position changes with load/fuel etc. Might also need to change the centre of lift value if its listed in the air file.
This is where in real life the designers choice of aerofoil can make or break the aircraft. In FS it seems a bit more simplified, but again its the creators choice of curve that does likewise! Jerry Beckwiths FDWB ( & I suppose Airwrench) tries to create curves for various known sections, but not sure how accurate they are.
Real life curves & data are available on the web, & most I think are calculated results - clever these aero boys!

Not a lot of help maybe, but thats my offering, if it helps at all - look at a Whitley & its attitude!
Keith

I'd sooner not look at a Whitley at all thanks

Trying to determine exactly what's happening in the few shots I've found of a Lincoln flying (or any aircraft for that matter) is difficult but it does appear to have a slight nose-up attitude. Of more concern is the over-sensitive trim which makes hand flying a chore.. you're either pulling back on the stick or pushing it forward. Without any fiddling.. this is definitely an AP girl!

ATB
DaveB