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The Continental O-300-powered C172s ("H" model in particular)

This is yet another little romantic piece about a a type/variant of aircraft I have flown this year. It’s about the very early Cessna 172s with the 145-hp O-300 engine. These are getting rather rare in Europe, at least on the rental scene.

Yesterday, I have flown a beautiful 1970 Reims-built Cessna 172H, with that smooth 6-cylinder engine. Just sweet!

Here it is:

I just like the looks of it. Personally, I prefer these “modern-look” 172s over the classic, straight tail ones and even more so over the swept-tail fastback ones. (I know, these have a few advantages, but I still prefer the the G and H and K models).

Puerly rationally speaking, there is very little speaking for these O-300 172s over the O-320-ones. The O-300:

  • has a bit less power
  • tends to leak oil
  • is heavier than the O-320
  • means two more cylinders to maintain and replace
  • uses a tiny bit more fuel than the 150-hp O-320
  • tends to make carb ice much more than the O-320

…but still, they fly and sound so beautifully!

It’s similar to the 150 vs. the 152… there is very little about the 150 which is “better” than the 152. Yet, 150s have so much more “soul” than 152s… IMHO.

An interesting point about these Continental-powered 172s is that they were produced both in Wichita and in Reims, but whilst Wichita switched to the Lycoming O-320 already in 1968 (“I” model), Reims continued to build the “H” model with the Continental engine (itself being license-built by Rolls-Royce, of course) and then the “K” model until the end of 1970, and only later in 1971 switched to the “L” model with the O-320. Hence, these Reims-built 172Hs are some of the “youngest” O-300-powered 172s out there in the world.

Funnily enough, the POH for this 1970 Reims-built 172H here is for both the Lycoming and the Continental versions of the 1970 model year.

I will show some of the features of these O-300-powered aircraft, to serve as a little intro for those who have so far only flown the Lycoming ones (the M, N and P models are the most common ones in the European rental/flying school/aeroclub scene).

First of all, the O-300 172s can easily be identified by the dual exhaust vs. the single exhaust on ones with a Lycoming engine

Note: for noise reduction, some of these aircraft have had a Gomolzig muffler installed, which does away with the dual exhaust sticking out of the bottom of the cowling.
See here for an example:

Here is a look into the engine compartment. Through the oil inspection hatch, you can only see the very rear of the engine, but not the cylinders. As with other Continental engines, you have an oil filler port which is separate from the dipstick port.

All the Continental-powered 172s (except for the very last Reims-built ones) still have the steel-spring main landing gear (as opposed to the tubular steel one in later models), which make smooth landings a little bit more difficult.

(For who is into these details, here is a photo of one of those very rare Reims-built “K” versions, still with the O-300, but already with the tubular-steel landing gear:)

If you look closely at the two above photos, this 172 I flew also does not have the original wheel pants (“spats” in BE). From the factory, the F172Hs still had the 1960s-style wheel pants, not the “racy” looking ones installed here (used in 1971-1974), so these must have been fitted at a later stage, I assume.

W&B-wise, these 172Hs are a bit limited as far as useful load is concerned. As I said, the O-300 engine is a bit heavier than the O-320. MTOW of the F172H is 1043kg. The empty weight of this aircraft here (which admittedly, has a a load of nice avionics installed) is 703kg, so that leaves you with only 340kgs of useful load. In other words, flying with 4 on board is practically impossible. If you fill up the tanks (144 litres usable), then it’s a 2-seater plus baggage rather than a 3-seater. (In contrast, most M, N, and P models are 660-690kgs empty. The very early 172s tend to be even noticeably lighter, but they also tend to not be equipped quite as well).

Moving to the cockpit now, this is the (highly upgraded) panel of this 1970 F172H:

As you can see, it includes:
-all new instrument panel and placards
-new yoke
-modern avionics, including a GTN750 and an STEC autopilot.

This one even has traffic and some kind of weather gear on board:

The interior has also been very nicely redone:

Here are a few more differences between the “older” and the “later” models…
The 172H still has the old style, non-gated flap selector:

But also, you can see, this example here has later been fitted with a digital flap position indicator. Flaps go down to 40 degrees (this was the case until the 1980 model year).

The lights and pitot heat switches are of the push-pull type. Not a problem.

The original airspeed indicator on these old Cessnas had MPH on the primary (= outer) scale, and knots on the inner scale only. This catches out some pilots transitioning from later models:

The engine instruments are on the far right in all Cessna 172s up to the 1975 model year, which is far from ideal. It’s hard to read the RPM gauge properly, due to parallax error. Having a carb temp gauge is useful in these O-300-powered Cessnas, I guess.

That’s about all there is to know when coming from an M/N/P model. Let’s go flying! Takeoff cceleration and climb rates are as you would expect with 145 hp. These aircraft also cruise a bit slower than the later versions. Expect 95 KIAS, max 100 KIAS if you push it a bit. That’s at low level and in low temperatures. So let’s call that 100 KTAS, whilst burning about 32 litres. (It can take ehtanol-free mogas, just like the later Lycoming-carburetted ones, N model excluded).

But boy, the 6-cylinder engine makes it “feel” nice! Here’s a little clip taken in flight and during taxi, which maybe gives an idea how nice it sounds:

Oh, since this flight was out of Bonn-Hangelar (EDKB), I’ll add a couple of shots of the city of Cologne and of Cologne-Bonn airport (EDDK)…

And this is Bonn-Hangelar (EDKB), located south of the city of Cologne, with its infamous “precision traffic circuit.” (Nowadys, enforcement is not as bad as it was 4-5 years ago):

But the problem is obvious: to the north, you have the CTR of EDDK. Hence, the circuit is to the south, but it’s full of built-up areas there, so the downwind invariably has to be over these built-up residential areas. They want to you aim at speficic buildings/landmarks in order to at least try to minimize the noise for most of the people.

EDKB is very busy place (one of the very busies of all German GA airfields), but it’s also a bit weird in many regards, and I also find it little “friendly”. Lots of politics there, lots of do’s and don’ts, and not an awful lot of good atmosphere. No instrument approaches either, and not even any runway lighting. Well, you can’t have everything, I guess.

Final for 29:

Anyway, I really liked this O-300-powered F172H. As long as:

  • you don’t have to take care of the maintenance
  • you don’t need a huge amount of performance

…it’s a wonderful plane for VFR bimbling and shortish cross-countries. Anyone on the forum fly a 172H?

If you are interested and broadly located in the Cologne or Bonn areas, this one here is beautiful and available for rent (no club dues) at EDKB at a competitive price. See (they also have “N” and “P” model 172s as well as an Archer III).

Last Edited by boscomantico at 19 Nov 21:18
Frankfurt (EDFE, EDFC, EDFZ), Germany

I have flown them and agree they are smoother – Richard Collins claimed they had the best quality build of the 172 series, at least of the US production series. That is a very nice example.

Unless they have been carefully looked after, these 50 year plus Cessnas can have corrosion issues in the wings. Many have been left out for decades. One of the advantages of tube and fabric of similar vintage, like Tigger’s broom, the regular recovering every 20 years or so ensures airframes are inspected, everywhere.

Enstone (EGTN), Oxford (EGTK)

Of course, they all are vintage aircraft and must be treated as such.

One (possibly minor) aspect is that allegedly, all Reims-built Cessnas have been „corrosion-proofed“ by the factory, whereas in Wichita, this has become standard only after the restart in 1996. What I never quite understood is how much of an effect some one-off anti-corrosion treatment done some 50 years ago can have on the condition of an airframe 50 years later. I guess you can still have perfect ones from the US as well as destroyed ones from France. But anyway, when in doubt, a 50-year old Reims-built airframe is probably a better bet than a 50-year old Wichita-built one.

Last Edited by boscomantico at 20 Nov 12:21
Frankfurt (EDFE, EDFC, EDFZ), Germany

For the optics, I do like the short legged slant tail fastbacks best (B and C models). Here is our 172B in direct comparison to a 172D.

The nicest feature of these legacy 172s are their manual flaps. It took Cessna some time to develop a real practical electric flap system. They went to a variety of toggle switches and some have a nasty lag (the flap motor keeps on running several seconds after the toggle is set back to neutral. I know this behviour of one F172F and one C172G).

boscomantico wrote:

All the Continental-powered 172s (except for the very last Reims-built ones) still have the steel-spring main landing gear (as opposed to the tubular steel one in later models), which make smooth landings a little bit more difficult.

That’s not the only reason. There was only the 1969/70 k-model with the tubular spring gear and the old (classic NACA 2412) airfoil. With 1971 Cessna introduced the larger nose radius to the NACA 2412 with the so-called “chamber lift wing”. That has a much bigger influence on landing characteristics than the gear design. On top of that, the width of the gear was increased with the tubular gear springs. But the main effect of the smoother landings in later models are aerodynamic, especially in comparison to the early models with round wing tips.

Inside the sky.
EDXE, EDXF, Germany

We have an F172M (1975) that has been with our club at ESME since 1979. A couple of years ago we did a total renovation (engine, paint, interior) where they removed and inspected and painted everything. It is a Reims model and they found zero corrosion.

It went from this (1975):

To this (2008)

To this (2017):

Last Edited by Dimme at 20 Nov 12:49

mh wrote:

For the optics, I do like the short legged slant tail fastbacks best (B and C models). Here is our 172B in direct comparison to a 172D.

I’m with you on that… although my choice would be a 170B, which is almost a 172.

Very nice to read a write up on the simple but timeless 172s and learn that 0-300s were used a little longer for French production while the test of plane stayed in parallel. The O-300 engine is remarkably smooth. I understand they changed US production to Lycomings in ‘68 because by then they’d decided that the Cardinal needed an upgrade to 180HP but had already made purchase commitments for 150 HP Lycoming engines.

It makes me smile to see newer style 172s, even though they may indeed be almost 50 years old, referred to as vintage aircraft. Anything from the 70s on is late model to me – I call my ‘71 my ’new plane’

boscomantico wrote:

What I never quite understood is how much of an effect some one-off anti-corrosion treatment done some 50 years ago can have on the condition of an airframe 50 years later

It’s not so much one-off as it is ‘forever’ (almost). An internally epoxy primed structure painted in production 50 years ago can look brand new internally. Zinc chromate as used on circa-1960 Comanches is not quite so good, but almost – it has a dramatic effect compared with bare aluminum. I also have a set of 1946 zinc chromated wings hanging on my hangar wall which look pretty good with fabric stripped.

Last Edited by Silvaire at 20 Nov 15:28

In these years Reims Aviation also built the 210hp FR172 which is way more capable and more fun than the 145hp F172 you described.
It features a nice 6 cylinder Conti IO360 engine which gives the Reims Rocket outstanding performance capabilities. You can easily and legally do a 4 adults, full tanks (196 L), take off from a 400m strip. ;-)

United Kingdom

Of course there is the Reims Rocket (and the similar, US-built Hawk XP, too).
A bit of a different beast, indeed. If I were in the market to buy a 172 for myself, it would indeed likely be a Reims Rocket, and not a “regular” 172, to get better IFR capability. But the latter is still the lowest-cost option to get 6-cylinder smoothness in an SEP.

We have a thread on the hot rod 172s here.

Do you fly / operate / own one? If yes, would you add some interesting input (possibly to the other thread)? @chflyer has a beautiful Hawk XP, and @Fenland_Flyer too, I believe.

Last Edited by boscomantico at 22 Nov 09:09
Frankfurt (EDFE, EDFC, EDFZ), Germany

Flight International 23 July 1970

“Free Ford Capri given with this aircraft“

Last Edited by cessnatraveller at 22 Nov 09:37
United Kingdom

Strangely a good Ford Capri today may be worth more than a Hawk XP!

Enstone (EGTN), Oxford (EGTK)
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