C172 float version not being able to take-off

[BrianW 124]

1 hour ago, NorwegianAviator said:

However, there are some aspects about the takeoff process that doesn't quite feel right to me

So I don't have XP12 yet, but "feel" is a key word.  Finding the proper attitude on the step in a real floatplane is something that is mostly done by feel.  When on the step you can sense the acceleration and deceleration to find the sweet spot.  Something our desktop sims can't do.

 

On 9/11/2022 at 5:25 PM, Murmur said:

Keep in mind the default weight in the C172 floatplane in XP is wrong, it's 2500lbs whereas the real aircraft MTOW is around 2200lbs, so you should use 2200lbs as max weight.

Do you have a source for this?  I've never seen floats cause a decrease in MTOW.  They do significantly reduce useful load though, especially in something like a 172.  I suppose if the floats were smaller it could be a buoyancy limitation, but the 172XP I learned in had a MTOW if 2550 regardless if it was on wheels or floats.

[Murmur 3,940]

7 minutes ago, BrianW said:

Do you have a source for this?  I've never seen floats cause a decrease in MTOW.  They do significantly reduce useful load though, especially in something like a 172.  I suppose if the floats were smaller it could be a buoyancy limitation, but the 172XP I learned in had a MTOW if 2550 regardless if it was on wheels or floats.

I found this C172P floatplane manual:

https://www.airtreknorth.com/uploads/4/7/2/4/4724302/cessna-172p-poh-section-9-supplement-float_plane_supplement_rv2.pdf

It says 2200 lbs MTOW whereas the standard C172P should have 2400 lbs MTOW.

They have a 160BHP engine though, so the 180BHP C172 modeled in XP12 might have a different MTOW indeed.

I couldn't find any C172 floatplane on the FAA TCDS with a MTOW above 2200 lbs, but there are a lot of TCDS for all the different C172 versions so I might have missed it!

 

[BrianW 124]

Interesting, it does look like a buoyancy limitation.  Those are EDO 2000 floats, I didn't realize that was what the default conversion used.  The FAA requires each float support 90 percent of the gross weight.  Our 172XP has EDO 2440s, so no limitation.  

[blingthinger 648]

I'm also finding that crosswinds will make it interesting. If I let the wind turn the nose upwind completely first, while at a standstill on the water, all is stable and am able to get off the water more quickly. Even 4-5 kts is enough to make me really work for it when skimming along at 40kias. 

This is so awesome.

[blingthinger 648]

Haven't confirmed this theory as I'm not at the computer, but I think the reason the skittishness happens with crosswind is because the floats are hitting the small (but still 3d) waves at non-90deg angles.