Real TAS in a 180hp C-172

DKirkpatrick

DKirkpatrick

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DKirkpatrick
Hello. Looking at a C-172 w 180hp conversion, constant speed prop. Airframe is '62 to '64... can't remember. It's had a cuff wing and flap gaps put on it.
Anybody know what kinds of TAS to expect in this airplane?

thanks alot

dan
 
A modern C172 with 180hp shows a book speed at 112-119 kt TAS at 65-75% power at 8000 feet, standard conditions. About the same as my Traveler. But real life speeds may be a bit slower. I can usually outrun most C-172s in cruise.
 
chemgeek said:
A modern C172 with 180hp shows a book speed at 112-119 kt TAS at 65-75% power at 8000 feet, standard conditions. About the same as my Traveler. But real life speeds may be a bit slower. I can usually outrun most C-172s in cruise.
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The late model ones will absolutely do book performance when they are actually flown by the book. I haven't flown one in quite some time but I remember verifying the performance every time I flew one cross country.

Unfortunately, what the late model airplanes will do may not be what the airplane in question will do. It has some mods and the wing is different, all of which will be a factor.
 
what you want is a 172RG baby.
Mv5dCk0.gif

:D
 
Kenny Phillips said:
110 kts indicated. Early 172s are pretty draggy.
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Wow ... it would be humbling to have one of them Light Sport experimentals go slipping by ... :p

... of course you do have the back seat along with the higher fuel burn! :D
 
The 172N 180 I used to rent here would true out somewhere between 110 and 120.. at least according to the utilities thing on the 650..

What you got though was a very impressive climb rate..!

My absolute disdain for the Skyhawk is well known on this forum but I actually really enjoyed flying this particular example, it was dialed in just right it was a real pleasure to fly
 
On topic - depends on the power setting, altitude... can they send a copy of the appropriate page in the POH that show the table?
Off topic - those AV-30s look nice!
 
I can do 125/130 TAS in my ‘77 180HP. We have the flap gap seal mod and the wheel pants on.
 

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Almost 600 hours in a G model w/ the 180hp fixed pitch, gap seals, and a horton STOL kit and I think my average groundspeed in the Garmin 530 was something like 117 knots.

It also was afaik the only 172 I’ve ever heard of making it in to the flight levels.
 
ktup-flyer said:
You have everything you need to calculate TAS in that picture.
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I get TAS = 110.6
Which is why I traded my C-172n/180 for a faster plane.
The only thing I miss about the 172 is the useful load. It came as a surprise to me that I could not just put four people and luggage in the Bonanza and go like I could in the 172. (As long as the luggage wasn't to drastic).
 
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Common for Tach to read 100 RPM low.

Often ignored when setting Cruise Power.

Hence your % power would be higher.

Hand held tach will help here.
 
Magman said:
Common for Tach to read 100 RPM low.

Often ignored when setting Cruise Power.

Hence your % power would be higher.

Hand held tach will help here.
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Yep. Ours (the club) has a little placard that it reads 100 RPM low. I didn't realize until your post that was due to the 180HP conversion.
 
Sorry if I wasn’t more specific.

The Tach error is unrelated to the conversion.


As mechanical Tachs age they tend to read lower.

Oddly; doing a PB on an Aerobatic I found one of the few Tach that read high.


Not only will an incorrect Tach affect your Airspeed but since most folks use

the recording feature for Mx it will also impact time for ADs , o/h etc.

by a little.
 
I made a lookup table to determine TAS in flight. It is very easy to use even when bouncing around in turbulence. I actually have made 2. The first one was for my Cherokee 140, then I made another one for my Mooney. Here is a discussion on how to do it. There is a lot of information about how fuel consumption varies with TAS, but you don't need to know that to create a table of TAS. Hope this helps. Have fun!

https://airfactsjournal.com/2014/02/knowing-true-airspeed-fuel-management/
 
Look out ya'll.... somebody gonna come along in this thread and argue you can't possibly get a TAS of xxx knots and suggest you fly four legs at 90 degree headings and somehow use GS to calculate your TAS... just sayin...
 
TAS = IAS + 2% per 1000' MSL. This will get you within a knot or two almost always at non oxygen altitudes. Or you could spin the whiz wheel to get it down to the exact knots.
 
68 172 with Alcon conversion(180hp/csp) with flap gap seals and power flow exhaust. 125kts/145mph TAS 6-8 thousand feet at 70% power(23/2300 or 22/2400). Be sure to get aux tanks since you will burn 10 gph which will cut down on your range despite the extra speed. 600 nm very doable non stop with 60 gal fuel. Anything further, I take the bonanza 100gal. with tips. The Cessna satisfies 80% of my flying, is half the expense to own. Ivae owned both for 15yrs, but just sold the bonanza, PS, I’ve seen some 172/180hp that did not get that speed, but if one wants speed, don’t get a 172, only if you want a practical, comfortable, easily to maintain aircraft that performs well at higher altitudes.
 
Eldorado — that's probably very similar to this airplane. And all the aforementioned reasons are a good way to sum up why I want one. This one doesn't have the pants on, but has a cuff wing and flap gap seals... constant speed prop.
Thanks all for the input
dan
 
Our club has a 1976 C-172N with the 180 hp conversion. Fixed pitch prop. I plan for 114 knots.
 
I think the raptor was supposed to be 250+ true so I don’t think it’s out of line to get 200 or so out of a 172. Maybe add some gap seals and some extra cooling hoses
 
MrAnderson said:
I think the raptor was supposed to be 250+ true so I don’t think it’s out of line to get 200 or so out of a 172. Maybe add some gap seals and some extra cooling hoses
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And ballast.
 
MrAnderson said:
I don’t think it’s out of line to get 200 or so out of a 172. Maybe add some gap seals and some extra cooling hoses
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Good coat of wax and some nice pinstripes and you will have to watch out for speed restrictions under 10k'.
 
1) The 180 is the engine the Skyhawk always should have had. So much nicer than the standard 150 hp

2) I don't go that much / if any faster in the 180 hp version, but but benefit is that it increases the load so much I can actually carry 4 adults and luggage, and it climbs much better. For short field and/or grass, I much prefer the 180 version.

3) I'd recommend to anyone buying a Skyhawk that if they have the option to get a 180 version, take it.

4) I wasn't aware there was an option of putting a CS prop on a Skyhawk. Is that true?
 
WDD said:
I don't go that much / if any faster in the 180 hp version, but but benefit is that it increases the load so much I can actually carry 4 adults and luggage, and it climbs much better.
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A big plus is that the extra power lets you climb at a higher airspeed, keeping the engine nice and cool. I cruise-climb at 500 fpm all the way up to cruising altitude, indicating 105-110 knots down low, and maybe 90-95 KIAS at 10,000'.

For short field and/or grass, I much prefer the 180 version.
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Yup.

I'd recommend to anyone buying a Skyhawk that if they have the option to get a 180 version, take it.
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Double yup.

I wasn't aware there was an option of putting a CS prop on a Skyhawk. Is that true?
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I believe that was only with the Avcon conversion, no longer available.
 
I have a C175B with a MASA 180 hp conversion with constant speed. Trues out at 122 knots 8K feet. No wheel pants, 700 on the mains and 600 on the nose. The real advantage is the rate of climb.
 
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