# Contact Points Question

This is from the C208 contact points:

point.0 = 1, -2.3, 0, -4.18, 750, 0, 0.5, 22, 0.21, 3, 0.5, 0, 0, 0, 0, 0
point.1 = 1, -15.8, -6, -4.14, 2000, 1, 0.5, 0, 0.26, 3, 0.5, 0, 0, 2, 0, 0
point.2 = 1, -15.8, 6, -4.14, 2000, 2, 0.5, 0, 0.26, 3, 0.5, 0, 0, 3, 0, 0
point.3 = 17, 1, 0, 1.7, 1, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0
point.4 = 2, -13.7, -26.2, 5.7, 350, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0
point.5 = 2, -13.7, 26.2, 5.7, 350, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.6 = 2, -36.83, 0, 2, 750, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0
point.7 = 2, -39.8, 0, 12, 350, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0

In the first parameter, I know that “1” is a wheel and “2” is a scrape point. What the heck is a “17”???

So nobody knows what a type “17” contact point is?

17 is not listed in the SDK docs, but the 14th parameter maybe gives a clue. 7 in that position is the sound ID of Aux1 Scrape. So maybe just another type of scrape point.

https://docs.flightsimulator.com/html/index.htm#t=Content_Configuration%2FSimObjects%2FAircraft_SimO%2FFlight_Model_Definition.htm

I’ve read through all of that and I still have the FS9 SDK documentation too. I’m just wondering if it actually means something, or if it’s a typo from Asobo.

If I interpret the numbers correctly, it is located in front of the propeller. Or maybe it is the propeller? The engines.cfg for the C208 says
`Engine.0 = 0.3, 0, 1`
so the
`point.3 = 17, 1, 0, 1.7, 1, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0`
is 0.7 feet in front of it, and 0.7 feet above. In case the engine position means the center of gravity of the engine, it could well be that the propeller axis is 0.7 feel higher. Does not seem likely, though, the PT6 is pretty symmetric around the axis. Maybe the Engine.0 position is the bottom of the engine? Although why the sim would need to know that I can’t imagine.

By the way, while discussing contact points, it is really unbelievable how fragile the simulator is if you get some contact point values “wrong” when iterating the development of a new aircraft.

And of course there is no message or log file actually telling what is wrong, it just crashes. Or hangs. Or throws your aircraft up to 275000 feet (or whatever the maximum was).

Infuriating. I am developing a seaplane and getting the contact points right to enable landing on water is annoyingly slow when you have to restart the simulator every now and then. It seems that even if the actual seaplane in question had no wheels, you need to lie that the MSFS aircraft has wheels anyway, otherwise it crashes or hangs when you land on water.