Real TAS in a 180hp C-172

Discussion in 'Cleared for the Approach' started by DKirkpatrick, Feb 5, 2021.

  1. DKirkpatrick

    DKirkpatrick Pre-takeoff checklist

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    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
     
  2. Kenny Phillips

    Kenny Phillips En-Route

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    110 kts indicated. Early 172s are pretty draggy.
     
  3. chemgeek

    chemgeek Pattern Altitude

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    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.
     
  4. Cloudhound

    Cloudhound Pre-Flight

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    I see 120kt at cruise in an '02 172SP, fixed pitch.


    upload_2021-2-5_15-47-51.png
     
  5. mondtster

    mondtster En-Route

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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.
     
  6. hindsight2020

    hindsight2020 Final Approach

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    what you want is a 172RG baby.
    [​IMG]
    :D
     
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  7. Daleandee

    Daleandee Cleared for Takeoff

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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
     
  8. Tantalum

    Tantalum Final Approach

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    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
     
  9. ktup-flyer

    ktup-flyer En-Route

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    Less slow, but still slow.
    IMG_1565 copy.jpg
     
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  10. asicer

    asicer Final Approach

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    Too bad you don't have a picture of the AV30's TAS.
     
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  11. ktup-flyer

    ktup-flyer En-Route

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    You have everything you need to calculate TAS in that picture.
     
  12. asicer

    asicer Final Approach

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    What??!? I have to brain??!? :)
     
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  13. Sluggo63

    Sluggo63 Cleared for Takeoff

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    "SUPPLEMENTAL" is spelled incorrectly. ;)
     
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  14. ktup-flyer

    ktup-flyer En-Route

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    I just put them in ;) Placard came with the airplane lol
     
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  15. Deelee

    Deelee Cleared for Takeoff

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    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!
     
  16. ARFlyer

    ARFlyer En-Route

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    I can do 125/130 TAS in my ‘77 180HP. We have the flap gap seal mod and the wheel pants on.
     

    Attached Files:

  17. Pilawt

    Pilawt Final Approach

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    Same here. '78 172N, 180 hp, fixed prop, factory wheel & brake fairings, flap gap seal, Maple Leaf exhaust fairing.
     
  18. DavidWhite

    DavidWhite Final Approach PoA Supporter

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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.
     
  19. JOhnH

    JOhnH Touchdown! Greaser!

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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).
     
    Last edited: Feb 6, 2021
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  20. MauleSkinner

    MauleSkinner Final Approach

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    ...but you learned to stay out of thunderstorms?:eek:
     
  21. asicer

    asicer Final Approach

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    Well that's odd. I get something different:
    Screenshot.png
     
  22. Magman

    Magman Pre-takeoff checklist

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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.
     
  23. BrianNC

    BrianNC En-Route

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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.
     
  24. Magman

    Magman Pre-takeoff checklist

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    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.
     
  25. JOhnH

    JOhnH Touchdown! Greaser!

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    Oops, you are right. That's what I get when I use 6 Centigrade too. I originally used Fahrenheit because that is how my OAT sensor reads.
     
  26. hindsight2020

    hindsight2020 Final Approach

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    How does one fly a mag heading on that setup?
     
  27. kayoh190

    kayoh190 Administrator Management Council Member PoA Supporter

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    Mag heading? Dude, why would I do that? There's a magenta line right *there*. :p
     
  28. William Pete Hodges

    William Pete Hodges Pre-takeoff checklist

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    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/
     
  29. Deelee

    Deelee Cleared for Takeoff

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    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...
     
  30. chemgeek

    chemgeek Pattern Altitude

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    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.
     
  31. DavidWhite

    DavidWhite Final Approach PoA Supporter

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    I think I was a few hundred miles from the nearest cloud!
     
  32. Eldorado

    Eldorado Pre-takeoff checklist

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    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.
     
  33. DKirkpatrick

    DKirkpatrick Pre-takeoff checklist

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    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
     
  34. Ghery

    Ghery Touchdown! Greaser!

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    Our club has a 1976 C-172N with the 180 hp conversion. Fixed pitch prop. I plan for 114 knots.
     
  35. MrAnderson

    MrAnderson Pre-Flight

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    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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  36. jsstevens

    jsstevens Final Approach PoA Supporter

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    And ballast.
     
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  37. Deelee

    Deelee Cleared for Takeoff

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    Good coat of wax and some nice pinstripes and you will have to watch out for speed restrictions under 10k'.
     
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  38. WDD

    WDD Pattern Altitude

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    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?
     
  39. Pilawt

    Pilawt Final Approach

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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'.

    Yup.

    Double yup.

    I believe that was only with the Avcon conversion, no longer available.
     
  40. RangeRider

    RangeRider Pre-Flight

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    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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