2790s on an early 180?

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Blakey
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2790s on an early 180?

Post by Blakey » Wed Oct 05, 2016 4:04 pm

I have a 1957 180A and I am looking for a set of amphibs. Has anyone ever seen an early 180 on 2790s? I'd like to have the bit more flotation than the 2700s give.
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PilotDAR
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Re: 2790s on an early 180?

Post by PilotDAR » Fri Oct 07, 2016 7:38 pm

I would expect that that combination would not meet the design requirements for approval for performance and gross weight. Even a 180 on 2705's is close to not being approvable. It is for this reason that many 182's which are converted to amphibs end up with a power and gross weight increase STC, and really become a different plane.
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Greysierra
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Re: 2790s on an early 180?

Post by Greysierra » Mon Oct 31, 2016 7:31 am

We run a 1977 180K on Edo 2960 straight floats in the summer.

Having said that, this aircraft also has Kenmore Air Harbor STCs that allow a gross weight increase to 3190lbs and a O-520-KAH1 Continental Engine.

Not sure if that helps.
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PilotDAR
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Re: 2790s on an early 180?

Post by PilotDAR » Mon Oct 31, 2016 6:13 pm

A 180 with a gross weight increase, and 520, is a near 185. Not quite, but close. Fine, if that's what you want to do, those are good mods, but there can be a couple of lesser known gotchas:

If the plane also has a STOL kit, which is pretty common with those mods (and a darn good idea), it may not have been evaluated for fuel flow at very high AoA. the STOL kit allows the plane to achieve higher AoA than the engine/airframe STC was intended to handle. With no fuel pumps and header tank, engine stumbling is possible, I've done it a couple of times during testing on these mods. My first experience with this (anticipated) was in a carburtetted 520 185 on wheels, and was very exciting!

If the fin is not changed, you'll probably have the low dorsal fin of the 180 (though I think some of the very last 180's made had the higher 185 dorsal fin). The difference is the greater susceptibility to rudder lock at very high AoA and yaw. Flyable, but not as pleasant in that condition.

The heavy 180/182/185 on amphibs also glides differently, and some training and practice to an actual landing on both land and water is a good idea.

For those considering mods to 180 series Cessnas, there are a lot of good ones out there, but your should know the implications, particularly of mix and match. The book "Cessna, Wings for the World" by Thompson is a very worthwhile read.
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Wyatt Earp
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Re: 2790s on an early 180?

Post by Wyatt Earp » Tue Nov 01, 2016 10:01 pm

2790's or 2960's are not approved on the early 180's as per the type certificate due to the length of the floats.
There was a company that had a STC but it involved installing their rudder trim mod , which is not available any more
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