waterline of FS9 float planes in FSX

[George de Tuncq]

The older Fairchilds and Travel Airs on floats tend to sink in FSX. They float with the floats either slightly below the surface or awash.

For 1930's bush flying they are wonderful planes but the illusion of reality gets pretty bent when they sink so low in the water.

Is there a fix?

[spad54]

Not planned as of now, sorry

[Tom Constantine]

It's a contact points/center of gravity issue. Theoretically it can be fixed but it would take someone smarter than me with knowledge of contact points to tell you how.

[George de Tuncq]

I was hoping it was going to be simple, there I go again!

When you hit the "Y" key and enter slew mode the plane jumps to the correct waterline. I know the plane is not really displacing water to float so it has a basis for knowing where it should rest.

I am willing to play with the contact points and experiment. Which contact points are involved?

I thought that there would be two lines of identical numbers for the two floats but that is not so because I don't see two lines that match.

If someone would be so kind as to aim me in the right direction I will diddle the numbers and see if I can learn how to do it.

[Tom Constantine]

I'm pretty sure float contact points are type 4. Beyond that I am uneducated.

[leylandspurr]

Sadly I'm a very poor amateur in such matters, but, for what it's worth........

Here's an example of the usual breakdown of contact points. Note the first point position is zero rather than one!

//0 Class
//1 Longitudinal Position (feet)
//2 Lateral Position (feet)
//3 Vertical Position (feet)
//4 Impact Damage Threshold (Feet Per Minute)
//5 Brake Map (0=None, 1=Left, 2=Right)
//6 Wheel Radius (feet)
//7 Steer Angle (degrees)
//8 Static Compression (feet) (0 if rigid)
//9 Max/Static Compression Ratio
//10 Damping Ratio (0=Undamped, 1=Critically Damped)
//11 Extension Time (seconds)
//12 Retraction Time (seconds)
//13 Sound Type

This is an example from one I've played with, The Short Scion twin-floater (for conversion from FS9 to FSX);

//point.0 = 4, -7, -4.25, -7.5, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
//point.1 = 4, -7, 4.25, -7.5, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
//point.2 = 4, 4.5, -4.25, -8.6, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
//point.3 = 4, 4.5, 4.25, -8.6, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
point.0 = 4, -7, -4.25, -8.25, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
point.1 = 4, -7, 4.25, -8.25, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
point.2 = 4, 4.5, -4.25, -8.95, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0
point.3 = 4, 4.5, 4.25, -8.95, 1970, 0, 0, 0, 0.5, 2.5, 0.39, 0, 0, 0, 0, 0

Note the class (floats) is "4" in point postion zero and, as far as I can figure (I'm just a "simple Geordie lad", after all), the four contact points (zero to three) are of postions near the front and near the back of each of the twin floats. Minus and plus showing the distances left or right, fore or aft and above or below the centre of gravity. Obviously a single-hulled seaplane with wing tip floats would be rather different in layout but the principles remain the same.

You may, or may not, need to alter the centre of gravity height or static pitch (the angle the aeroplane adopts at rest) if these are also "off", best to catch the pause button just as the sim launches and take an outside view then watch what happens as you 'unpause' - if the plane 'kicks' or noses up or down then the the static pitch or CofG height are off compared with the contact points (which relate to what you see after the aircraft becomes active). The following are from a different aircraft to the Scion, which didn't need adjustment in this area.

//static_pitch = 14.360
static_pitch = 8.360
//static_cg_height = 5.900
static_cg_height = 6.050

In these examples you can see that I've disabled but retained the original settings with "//" so that I can always remember where I started from (essential with my memory!).

One problem I've found with all "ported over" floaters in FSX, is that there is a 'kick' or change in water attitude during the take off and landing runs, so you have to achieve an acceptable compromise to cover the appearance in all modes (again best seen from an outside view). The Scion example (above) was a frustrating one and I never achieved anything I thought acceptable. So, best of luck, we need more vintage floaters!!!

Leyland

[George de Tuncq]

Many thanks for the useful information. I am glad to hear that Scots keep busy with worthwhile activities during the long, dark and snowy winters.

Another member pointed me to the SDK's for both FS9 and FSX. Thankfully the information on contact points is the same for both sims. Again it is information that leads to patient slow manipulation of the numbers. I will never again lack for something to do. The slow process of making a change in the cfg, getting the sim back up, reloading the airplane, watching the result and repeating the process gives me more reason than ever to admire and thank the ones among us who do this for our pleasure.

And so to work, thanks again.

[leylandspurr]

Hi George,
My machine (a dual core AMD processor) will cope with FSX running minimised, while I 'doctor' and save the altered config, then just 'reset' the flight. Not that slow, but pursuit of perfection can lead to 'repetitive strain injury' (to both mind and body) - be warned!
The above doesn't work with some kinds of alterations, but "aircraft.cfg" and the ".air" file both can be altered 'on the fly' in this way.
Not much else to do around here when you get a winter like the one we just had - totally unused to snow that lasts and lasts (living by the sea, it's supposed to melt away very quickly).
Have to say I enjoy playing with cfg files (must be a masochist?). Scientific logic dictates you take big(ish) alterations, trying to get results either way from the ideal, then start refining with ever-decreasing-sized alterations.
Have fun (that's what we are supposed to be doing).
Leyland

[hurricane91]

Jan 25, 2010 17:48:51 GMT -5 George de Tuncq said:

The older Fairchilds and Travel Airs on floats tend to sink in FSX. They float with the floats either slightly below the surface or awash.

Which models are you working with?

[hurricane91]

If you are working with the Fairchild 71, I chaned the contact values in mine as follows;

point.0= 4, 6.719, 5.175, -9.000,
point.1= 4, 6.719, -5.175, -9.000,
point.2= 4,-12.120, 5.175, -6.700,
point.3= 4,-12.120,- 5.175, -6.700,

These values assume a full default loadout and were the only changes made. The photos show the aircraft at rest and where the contacts are now placed.
As Leyland said, there is a compromise to this, and keep in mind that I am not an expert by any means.

[George de Tuncq]

Leyland and Hurricane -- I was away all of March and didn't think about the waterline issue until today and so just found your posts. Thanks for the cfg mods for the 71, I will steal them with many thanks.

At my leisure (when is that?) I will tackle the Travel Air 6000 A & B. I have them floating right but they refuse to take off now so I will play with the cg. It will probably go slowly since it looks like winter is finally going to end here near San Francisco and I will stir outside.

George