C180 Performance-Kenmore GW STC

[superchamp]

Anyone here have any experience in C180's on floats with the Kenmore 3190 upgross kit, and 0470 motor. There are some out there with 1200+ pounds useful on floats, but wondering how they do getting it off the water. The one I've seen has PK3000's. Do they perform or is it legally useful load but practically useless? To me this mod makes it a 185 but with a smaller motor.

 

[twinjim]

kenmore stc

the stc is a farse! its a little metal plate that goes over an inspection hole which does nothing. i have this plate on my 180 float plane. save your money and load up plane as you wish. the only catch when we were 3500lbs
at 4000ft on the long lake, you have to get plane over hard on one float and yank full flaps to get off. its like an auto fuel stc. its only a sticker which makes the lawyers happy.

 

[mvivion]

If I recall correctly, though, this GW increase also requires the big dorsal fin, correct??? That's a yaw stability issue, so be careful with that.

MTV

 

[superchamp]

The one I looked at was a '74 J that had the 185 dorsal fin, this makes it legal at 3190 on wheels and floats. I think the dorsal fin can only be put on 71-76 models. After that the 180 came with the 185 dorsal fin. The only floats included on the STC up to 3190 are 2960's or Aerocets. Interestingly enough, its my understanding that on floats, only the gusset plate (or inspection whole cover) is required to go to 3190, and the 185 dorsal fin is NOT required. A 135 operator here has a '72 180 with the Kenmore upgross (plates installed) but NOT the dorsal fin. He is legal to 3190 on his Aerocet floats - Aeorcet has a " piggy back" STC on the Kenmore mod. If he takes his floats off, he is back to the regular gross weight. I would agree, that for the most part it is to keep you legal at higher weights, probably doesn't do a lot structurally for the plane. I could see this as a nice mod on a late model 180 with a PPonk motor. I also know it is fairly expensive mod, at least with the dorsal fin.

 

[aktango58]

twinjim,

It looks like a hokey STC, but it isn't!

Sit back and watch the horizontal Stabilizer on a full float plane on take-off that does not have this mod, then watch one with...

Or fly one...

Or look at a Horizontal Stabilizer after 6,000 hours compared to one that had the mod early in it's day.

the forces, including landing, will cause cracking in the front plate of the stabilizer, hence the .040 or .041 plate installed with a particular rivet pattern. Even though I could not get the gross Wt. increase, (early models not eligible), I put a front plate on my bird. It made the elevator more responsive.

Many would not feel it, but I flew the bird every day, so had a good feel for it.

As far as performance, Edo and Aerocett out perform the others off the water so much, that to even bring up the big Aqua and PK's in the same group is incorrect.

The mod is not a performance mod, but a strength mod. There is one operator here that flew 180's for years with stock engines and 3190 gross.

 

[180Marty]

Is this hole you guys are talking about between the brackets holding the top of the jackscrews?

 

[twinjim]

weight increase

I find it still hard to believe that this plate makes any difference. I don't remember exactly which hole it went over, however remember at the time laughing about it, like it could really play any significance, and felt duked, that i went through all that trouble and cash for that. I'm not an engineer but blessed with common sense. I don't think you could possibly feel the difference aktango58. Anybody else have some experience with this??

 

[mvivion]

Well, take a look at the modification to the V-Tail Bonanzas to improve their safety record. Doesn't look like much, but it apparently makes a LOT of difference. Sometimes, structural improvements may not look too impressive, but...

MTV

 

[aalexander]

Re: weight increase

I'm not an engineer but blessed with common sense.

So, what do you know about the specific problem which is addressed by the addition of the plate, what, specifically are the stresses involved and how has your "common sense" determined that the plate does not in fact resolve the problem?

Doesn't look like much, but it apparently makes a LOT of difference. Sometimes, structural improvements may not look too impressive, but...

This is true, Mike. If I understand correctly, the way they stopped wings from coming off of Electras was to remove metal from the structure. Changed the harmonics of the wing which was the problem. Obviously, common sense shows that this was wrong, because if you have wings breaking off of airplanes anyone with a lick of sense can tell you that you have to add to the structure to make it stronger. But then, the wings did stop falling off of Electras.

 

[m wittler]

As thee old saying goes "Your only as strong as your weakest link" !!

 

[twinjim]

weight increase

maybe your right?

 

[StewartB]

Late to the discussion, but here's some info. I have the Kenmore mod on my '75 180J. The 3190# gross weight increase requires the addition of a doubler on the stabilizer spar. That is consistent for G, H, J, and K models. The addition of the larger 185-style dorsal is required on all G and H models and also on J and K model landplanes. The J and K factory seaplane models were factory equipped with the big tail. All models also require the non-linear rudder centering spring when operating on floats. Again, the J and K factory seaplanes already had it.

Superchamp, your friend with the '72 airplane is incorrect. His H model is not STC compliant without the big dorsal in any gear configuration. The implied exemption from the big dorsal on J and K seaplanes was because they already were equipped that way. The STC has a supplement that specifies the large dorsal addition on all G and H airplanes and J and K landplanes.

You asked about performance? At 3190# and with stock power, the 180 is capable but sluggish. More horsepower helps but the limiting factor is the tail. At 3190 the elevator is not very effective at slow speeds. Brakes are alarmingly weak at that gross weight as well. If you want to operate heavy, make sure you have adequate room to do so safely. The plane flies fine but climb is slower and the ground/water requirements for leaving and returning are considerably greater than when flying at mid-weight or even at the old 2800# gross. And then there's the 2960 heel dragging issue! Skywagon water performance is all about trim. That's true at any weight.

Stewart

 

[superchamp]

Thanks for the late reply Stewart. I already bought a 73 182 with a Pponk motor, and had the seplanes west kit and Aerocet's installed. Only about 15 hours on it so far, as the ice only went out a few weeks ago, but so far it is very nice plane, and very capable of hauling good size loads of the water. Also exceptionally fast for a float plane.

 

[StewartB]

And the important question..........does wifey like it?

What's the useful and gross on a floated 182?

Stewart

 

[superchamp]

The wife and kids love the room and visibility, all the glass in back is nice for kids. The 4 inches extra cabin width over the 180/185 is nice. Kick back with the auto pilot on, put the Disney channel on XM radio, and the kids are content. On 73 and newer 182's on Aerocets with the Seaplane West kit, with a bigger motor and certain props, your legal gross goes to 3150 or 3350, depending on the motor. Actually even stock 470 powered 73 or newer go to 3150, and the 520 and 550 powered go to 3350, again there is a list of props that qualify. This upgross STC requires a strap on the spar, which went on mine when I had them put the wing extensions on, and a beef up on the strut. The upgross STC does not require extensions. The STC is supposed to be final this summer, as they were just wrapping up the flight testing with the FAA. When finalized I pay a few bucks to have the paperwork, and I am good to go. I'm not sure how the final STC will read, whether it will be just IO 520 or will include O520(Pponk). If it includes O520, I will have about 1300 useful on floats, if not I will have 1100 useful. Until final STC issue I have 900 useful (2950 gross). I know its still cool out, but it doesn't appear that 1200 pounds is any problem off the water. Still seeing 1000 fpm at that weight, and about 135 mph at 24 squared. This is with a 82 inch 3 blade Mac. Big floats are really nice with all the wind we've been having this spring. So far, I'm very happy.

 

[StewartB]

Very cool. Congratulations.

What will you do during the winter months? Fly it or pickle it? That thing would be a rocket ship on tires!

Stewart

 

[superchamp]

I flew it 3 hours on wheels with wheel pants before I had the SW kit and floats installed. It seemed to run in the low to mid 150 mph range. This was before extensions, so don't know if they will speed it up or slow it down. As for winter flying, I will fly my snowmobile for a while. Our northern MN winters the last few years have been such a SOB with cold, snow and lots of slush, that ski flying has been a real battle. Maybe I'll put the wheels on and fly somewhere warm for a week. If I still miss ski flying in a few years maybe I'll buy a small beat up 2 seat something taildragger and just leave the ski's on it year round. I won't miss trying to keep a runway frozen down on lake, keeping the plane blocked up out of the rising slush, scraping snow and ice off a plane stored outside in the winter, and prying frozen wing covers on and off in sub zero temps, I know that for sure. My winter flying from here on forward will involve rolling a plane out of a hangar. 15 years of fighting mother nature and she beat me soundly.

 

[storied180]

Late to the discussion, but here's some info. I have the Kenmore mod on my '75 180J. The 3190# gross weight increase requires the addition of a doubler on the stabilizer spar. That is consistent for G, H, J, and K models. The addition of the larger 185-style dorsal is required on all G and H models and also on J and K model landplanes. The J and K factory seaplane models were factory equipped with the big tail. All models also require the non-linear rudder centering spring when operating on floats. Again, the J and K factory seaplanes already had it.

Superchamp, your friend with the '72 airplane is incorrect. His H model is not STC compliant without the big dorsal in any gear configuration. The implied exemption from the big dorsal on J and K seaplanes was because they already were equipped that way. The STC has a supplement that specifies the large dorsal addition on all G and H airplanes and J and K landplanes.

You asked about performance? At 3190# and with stock power, the 180 is capable but sluggish. More horsepower helps but the limiting factor is the tail. At 3190 the elevator is not very effective at slow speeds. Brakes are alarmingly weak at that gross weight as well. If you want to operate heavy, make sure you have adequate room to do so safely. The plane flies fine but climb is slower and the ground/water requirements for leaving and returning are considerably greater than when flying at mid-weight or even at the old 2800# gross. And then there's the 2960 heel dragging issue! Skywagon water performance is all about trim. That's true at any weight.

Stewart

would it be 3190 with WingX, or more?

1977 180K big dorsal IO-520. i have wing x, doing the kenmore doubler now

 

[mvivion]

It may be helpful to look to the origin of the Kenmore mod. They had a small fleet of later model 180s that were operated as on demand and scheduled air taxis, as well as some flight training. Kenmore is based on the north end of a very large lake, and most of their destinations are also on fairly large water bodies. The gross weight increase gave them the option of carrying more weight on those daily trips…..meaning more $$$. But, as long as the mod was STC’d they’d have been fools not to have made more $$ from sales.
And BTW, while P-Ponk has got most of the attention regarding power increases in 180s, it’s worth noting that Kenmore had an O-520 mod long before P Ponk did. Again, designed for their fleet. Back in 1984, I got a quote from them to replace the TBO O-470 in my 66 H model with their kit.

 

[stewartb]

would it be 3190 with WingX, or more?

1977 180K big dorsal IO-520. i have wing x, doing the kenmore doubler now

3190.