172 'R' (160HP) to 'S' (180 HP)

[Victorian]

On the 'N' reg:

Is it possible to convert a 172 'R' model (160HP) to an 'S' (180 HP) simply by replacing the engine?

Does anyone here have any experience of this? What are the snags?

The 160HP 'R' always seemed a bit of a Cinderella in the training environment (2 Americans on board, hot n' high), but perfect for my mostly solo long distance touring. Would a converted aircraft have identical characteristics to a genuine 'S', or are there potential 'gotchas'?

Any advice welcome.

[ETOPS]

Hi Victorian

I just Googled C172 180hp STC and got this site..


C-172 Air Plains 180 HP Model R (http://www.airplains.com/index.php/parts/engine-conversion?id=83)

Looks like a performance boost as opposed to a new donkey.

[thing]

Can't help you but those extra 20 hp make a lot of difference. We have a 160 and a 180, the 180 also has the Horton STOL kit. It gets off the ground even on the grottiest grass strip in no time with a climb rate of about 1300fpm one up.

[localflighteast]

I must be in a minority . our school flies both the r and s models.
I find the s model more fuel hungry and not much else. I just find the balance feels wrong. More power but not the useful kind, it just feels like you have to fight it all the time.

[thing]

Our 180 is an M.

[PA28181]

I have flown the US-Army version of the 172 the "T-41 Mescalero" this has 210hp engine & VP prop & balloon tyres. (Las-Vegas North Terminal)

[maehhh]

At my flight school we used to have a 180hp S model and a 160hp R modell... both airplines reasonably new and IFR equipped. To be honest with you I happily went for the R whenever I could. Except for a minor difference in climb speed everything felt smoother in the R. It was even quicker in cruise... :ok:

[Silvaire1]

I have flown the US-Army version of the 172 the "T-41 Mescalero" this has 210hp engine & VP prop & balloon tyres. (Las-Vegas North Terminal)

Also built in France as the Reims Rocket. I flew one recently.

The FAA Type Certificate Data Sheet describes out what can be done within its constraints of the approved Type. STC's then add another set of possibilities. Will take a fair bit of research.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/724e90061c5bf3b1862576260063e599/$FILE/3A12.pdf

[Big Pistons Forever]

The mod only involves changing the prop and the induction air box. The big advantage is the extra 150 lbs of useful load. The R models are so heavy they are basically 3 place airplanes. The hp upgrade makes them much more useful.

[India Four Two]

The mod only involves changing the prop and the induction air box.


I'm confused (not difficult these days!). Does this mean that Cessna de-rated the engine by installing a finer pitch prop? Why would they do that?

And how does changing the prop allow an increased gross weight?

[Victorian]

Thanks for all those helpful replies chaps.

I agree about the 'R' being a 3 place plane, especially hot n' high where the 3rd place is for a dog!

However I've also found the 'S' harsh, heavy and no better in the cruise which is where I spend most of my time. So it will be interesting to see how this conversion pans out.

I'll report back.

[overandout]

I upgraded from Continental 0-300-D 145 hp to Lycoming 0-360-A4M 180 hp.
Enormous difference. Speed up from 95kts to 115 kts fuel now 33 ltr/hr. climb 1000 ft per min 18 mins to 10,000ft
Was the Air Plains conversion. Excellent kit . Highly recommended

[localflighteast]

its actually kind of nice to hear people agreeing that the S model is "harsh and heavy" (fantastic way of describing it)
I thought it was just me. I constantly feel that I'm wrestling the S model rather than flying it.

I'm fairly certain that our S model only has an extra 100 pound useful load as well.

[mary meagher]

While you're at it, stick a hook on the tail as well, then there will be a ready market for a useful glider tug!

When it comes to a classic frame that happily upgrades to a bigger, bigger and yet bigger horse up front, consider the J3 cub, that used to fly around with its cylinders protruding, back in the 1930's. Beef up the frame, stick on some flaps, add a 90 hp, you've got a Supercub! Used in the military for artillery spotting, one actually BROUGHT DOWN A MESSERSCHMIDT during WWII.

Add some more hp, 150 engine, beautifully balanced aircraft to fly, useful in so many many ways, take off and land using a rough short field, fly with floats, skis, tundra tyres, land on a levee or a sand bar or a beach, pull a banner, remove the cowling and doors, and fly in the open air! And then beef up the frame a bit more, soup up the Lycoming to 180, and that darling Piper will pull up a glider with 22 meter wingspan and a couple of heavy chaps, to say nothing of a turbo handy get-you-home engine hiding in the trapdoors on the rear fus...I really really miss my Piper Cub.

If anybody still wants to learn to fly a real aeroplane, GOFER is now used for training at White Waltham.

[Big Pistons Forever]

I'm confused (not difficult these days!). Does this mean that Cessna de-rated the engine by installing a finer pitch prop? Why would they do that?

And how does changing the prop allow an increased gross weight?

When Cessna restarted the C 172 line in 1996 the engine was changed from the previously used 160 hp carburated O 320 engine to the fuel injected IO 360. This bigger engine is normally rated for 180 hp. However to keep it the same as the old models the prop was pitched so that it would only develop 160 hp. Since the same 2400 lbs gross weight of the legacy airplanes was retained, performance stayed the same.

The problem is the new models fancy interiors and other design changes to make the aircraft safer, added weight. Thus the payload was significantly less than the legacy models. When customers started complaining Cessna decided to restore the engine to 180 hp and up the gross weight to 2550 lbs. The C 172 S now carries the same payload as an old 1980's vintage 160 hp P model C 172, but burns 1.5 gallons per hour more. Isn't progress wonderful :ugh:

[mary meagher]

Yep, power to weight ration, can't beat a Super Cub!

Stalling speed about 35 mph....

[India Four Two]

and up the gross weight to 2550 lbs.

BPF,
Thanks for the background info. Was the gross weight increase just a paperwork exercise or did they have to beef anything up?

[Big Pistons Forever]

BPF,
Thanks for the background info. Was the gross weight increase just a paperwork exercise or did they have to beef anything up?

Totally paperwork.

[VP-F__]

You could always look at adding a tuned exhaust