C150 vs C152

[Okavango]

Hi. I'm in an unfortunate situation where both the school 152's have been taken for their annual inspections at the same time, and we have a temporary C150 in the meantime (added to which I'm also waiting for a slot for my QXC!!). To put it bluntly, it seems a bit of a dog. The ASI is calibrated in mph and it seemed to be giving a cruise of about 70-75kts (equivalent) at 2200 rpm on the first flight I had in it. Is this normal variation? I thought the performance would be similar to a 152 (of which so far I've flown 3 and all seemed to perform almost identically) though this seems markedly slower at the same power.

[julian_storey]

Years since I flew one, but so far as I recall - one of the only differences is the flap selection.

In the 150 you have an up and down selector whereas in the 152, you have the rather better arrangement with the switch in the gate thing.

I seem to recall that they fly about the same.

[cpl4hire]

Its an old Plane and probably is a bit of a dog but dont forget the "getting it on the step" dodge.
ie. Level out at your cruising altitude but leave full power set for a few seconds so you accelerate to slightly faster than your normal cruise speed. Then reduce power to Cruise RPM (2300?) and re-trim for level flight.
You should find the 150 is flying level, rather than staggering around the sky in a slightly nose up attitude. It should "feel" a lot better.

Rgds

[dont overfil]

There are many different versions of C150s. Engine and propeller differences are what you are seeing. Read the manual for the particular aircraft, it may have a climb prop which may require as much as 2400rpm for the cruise. It should cruise at about the same speed as a C152, within about 10MPH.
There can be different flap deployment methods, a big lever, a hold down electric switch or a set and forget like the 152.
Most have 40 degrees flap with which you should use caution 'till you know what to expect.
It may also have different stall characteristics due to wing section, tail and tip design.
The list goes on. Read the manual.
The early straight tail ones were particularly nice.
DO.

[Pilot DAR]

The 152 does have a few more horsepower than the 150, and often a somewhat more coarse pitch propeller, so a little faster cruise can be expected. In a 150, 2200 RPM is on the slow side for cruise power. 2400-2500 will get you better results, particularly if you are leaning. The mixture distribution is more even at 2450+-, than at engine speeds faster or slower.

70kts does sound a little slow though. It could be that the prop on the 150 is pitched to a very low blade angle, for better climb. There are also wing adjustment cams, whose position can slightly affect cruise speed. I presuppose that the engine maintence is adequate. The O-200 is a fine engine if well cared for, but low cylinder compression can be a problem, and it will reduce power output. The O-200 is very unhappy running on 100LL, and this was another reason for the change to the O-235, which was very happy on leaded fuel. The 80/87 of the "old" days ran very well in O-200's. Though 80/87 was permitted to contain lead, it rarely did, so lead fouling was not a problem in the O-200, until 80/87 was no longer available. When 80/87 became difficult to obtain, and 100/130 became the "norm", the O-200's suffered terribly.

The flaps are different between the types, not in the selector (the few 1977 150's had the same "preselect" flap control as the 152's), but in the angle. All 150's have 40 degrees of flaps available, all 152's have only 30 degrees. That last 10 degrees is very noticable for short field work. The problem is that the aircraft is easily able to land into a runway too short to takeoff later. It also makes full flap overshoots a little challenging, though contrary to what you will regularly read here, a 150 will safely climb away with full flaps. I think that Cessna changed their thinking to no longer optimize short field performance, and more tend toward simpler trainer type performance.

Another difference between the types is that most if not all 152's are 24 volt electrical system. The O-200 engine was not available with a 24 volt starter and alternator.

You can play around with getting on the step, but the affect is much less noticable on the 150/152, than on other types. It's not a bad Idea, but not a big help either.

I hope this helps, enjoy the 150

Pilot DAR

[Pace]

PilotDar

I can remember flying two 150s one had an 80 hp unit the other a 130 hp unit.

The one was like an old dog the other like a bat out of hell.

Pace

[EchoMike]

(Single paragraph caused by unresolved obscure browser problem.) 150 is 100 hp, if older cylinders fitted, timing is retarded to 24 degrees BTDC, you'll lose about 3 or 4 hp which you really won't notice anyway. Later cylinders timing is 28 degrees BTDC, the AD note doesn't apply, you get all 100 (thundering) horsepower. 152 is Lycoming of 108 or 110 hp (depends on year), 28 volt electrics, flaps limited to 30 degrees. 70 lbs increase in MTOW. Overall performance is about the same between 150 and 152. Your 70 to 75 kts airspeed seems slow, go ahead and flog it a little, the O-200 likes to be run hard, 75% power all day long and it will lap it up. Variations: base engine is 100 hp O-200 on ALL USA 150s (there's no 80 hp option), 108/110 on all 152s. Rheims 150 (FR150) sometimes had a somewhat problematic Rolls-Royce O-240 of 135 hp (under license from Continental), few parts available any more, and they're expensive if you can find them. STCs for the 150 include 150, 160 and even 180 HP Lycomings, for the 152, there is a "Sparrow Hawk" conversion (prop & pistons) which takes it to 125 hp. If your airplane is really only going 70-75 Kts at cruise, either open the throttle some more or look for problems, cruise at 2,500 ft MSL on a 150 is right about 100 to 105 mph, or 90 KIAS. Check the ASI calibration, read the POH for 75% power at different altitudes. Best Regards, Echo Mike N150EM

[Pilot DAR]

EchoMike is right on....

[SFCC]

EchoMike is indeed right on.
cpl4hire is talking utter bohoolicks. Just like most other people that have never spent enough time reading their books.

[Put1992]

Apart from the ASI being in MPH as opposed to knots (you've still got the inner scale), and the flap selection being a bit different (it's more easier doing circuits in the 152 than the 150) there isn't a considerable difference. 152's with long range tanks obviously make a bit of a change when your taking flight planning into consideration.

Cheers

[First_Principal]

I get 85-90 KIAS out of my 150 but tend to run it at 2400 rpm or a little above most of the time. Rarely would I use much less than this, so I'm with the others, try pushing it a bit more - if you're in doubt it may be worth getting the RPM gauge checked out with one of those handheld digital strobe meters, some gauges can be out by 100 rpm or more without you being particularly aware of it. So while 2200 is quite low (for a 150) already you could find it's actually running at 2100 or even less. I wonder what it indicates when you do a static check? If you look it up for the particular prop you have etc you should be able to get a reasonably accurate idea of your expected static RPM and see if it differs much from that.

FWIW the 152 I fly doesn't perhaps appear to work quite as hard as the 150 but in practice there's not an enormous difference in route times between them.

[Pace]

For all you could ever want to know on the Cessna 150 series follow this link

Cessna 150 - Wikipedia, the free encyclopedia

Pace

[Okavango]

Thanks

Thanks to all who provided advice, your notes gave me confidence to set off on my qualifying cross country which I completed today. I tried the higher power setting and performance was just as you describe - it seemed to be just shy of 100 mph at 2400rpm in cruise. I've let the school instructors know as seemingly they had been flying it with power settings as per a C152.

[Final 3 Greens]

Okavango

The RR/Continental engine in the 150 can collect carb ice more than the Lycoming in the 152.

You may wish to do your FREDA checks very regularly and consider leaving the carb heat on for 30-60 seconds.

If the engine runs rough, keep the carb heat on, it will clear the ice causing the rough running.

Of course discuss the above with your instructor.

[Lost man standing]

Sorry, have to challenge Pilot DAR on the full-flap go around in a Cessna 150.

It might be that technically, this is possible, although I have never heard of anyone managing it. What it is not is safe! I have tried and failed myself, and know of at least one experienced instructor ending up in a field due to a fuse blowing on the flaps during a PFL. Unable to retract the aircraft would not climb away.

[Pilot DAR]

With due respect to the lost man standing, I cannot agree that the full flap go around is not safely possible. I agree that they require care, but if proper flying is executed, it can be safely done. I have done it at night, when my flap fuse blew (changing it in the dark while going around, seemed like a bad idea). I have also purposefully taken off with full flaps a number of times with no difficulty. I certainly am not suggesting others do this, but for those who would like to flame me, I will draw attention to the fact that the flight manual contains recommended flap settings, but no prohibited flap settings, I also own the plane, and planned well ahead (large frozen lake - no obstructions).

A full flap overshoot is a required design compliance element, and I am required to demonstrate that the aircraft can still do it after some aerodynamic modifications (installation of wheel skis). The text of the standard is as follows:

3.596.
(c) Balked landing conditions. The steady angle of climb at sea level shall be at least 1:30 with:
(1) Takeoff power on all engines,
(2) Landing gear extended,
(3) Wing flaps in the landing position.
If rapid retraction is possible with safety without loss of altitude and without requiring sudden changes of angle of attack or exceptional skill on the part of the pilot, wing flaps may be retracted.

If I can't make the plane safely do this, I do not approve the modification. My personal criteria is that rapid retraction is not possible, if the fuse could have just blown. It gets flown away full flaps. I do not retract the flaps at all, until I have seen a sustained climb. I'm not saying it's a great climb, but it will do it. I've even had mechanical Cessna flaps fail down! (broken flap track on floatplane) By the way, a 1:30 climb is pathetic.

There are other operations in which flap settings exceeding the flight manual recommended settings will produce results better that the recommended flap settings. Climb is not one of those.

I shall take the opportunity to glance off the comment about instructors as a measure of skill in piloting: There are good pilots, not so good pilots, and instructors. Instructors can be in either of the former catagories. I do not consider an aspect of an aircraft's handling or performance good or bad based upon the opinion expressed by an instructor, just because they are an instructor. I will listen to the opinion of a pilot's license holder with a lot of time on type, and experience on similar types. Instructors are a vitally important element of aviation, but not always the final stop for knowledge and wisdom.

There is no reason that you, as a pilot under instruction, or solo, when way up high, where it is extra safe, would not try a full flap go around, just to see how the plane flies that way. (hint, it's slow flight at full power)Things fail.... You may as well practice!

I hope that reassures you a little.

Pilot DAR

[Lost man standing]

Either you misread my post, or your definition of "safe" is somewhat different from mine. Assuming that the requirements were the same when the 150 was designed as they are now and it therefore complies, it can barely do so and only when in good condition. It certainly isn't easy to achieve any climb at all in a typical, battered, abused airframe with 40° flap. It is therefore not a good idea to suggest it is safe in a forum frequented by pilots of a variety of experience levels.

An instructor who has run the flying school which owns the aircraft for several years is probably about as good at flying a 150 as anyone. If he can't fly away in an area with no especially steep terrain, I reckon it isn't a safe manoeuvre!

[Mark1234]

I suspect the issue may well be to do with how slow one is willing to fly - in this day and age we are taught to fly with such fear of the edge of the performance envelope that most pilots aren't willing to get within a country mile of the low speed end of things. You'd have to be going pretty slow to climb with full flap.

PilotDAR what sort of airspeed are you using for a full flap climb?

Incidentally, I was given to believe (again by a crusty old instructor type) that the reason for the 30degree flap limit on later aircraft was to permit increased MTOW while still allowing the full flap climb requirements to be met.

Practically I've noticed little difference between the 150/152, other than I can't turn final in my customary (very high) position in the 152 without sailing past the numbers at a great height... that last 10degrees makes a big difference.

[Pilot DAR]

The information given to Mark1234 sounds the same as that I have heard, the 152 has a lesser flap limit due to less than adequate climb performance at gross weight with 40 degrees of flap. The 152 seems to have a propeller optimized more for cruise than climb. I have taken off 152's from runways where they struggled out where a 150 in the same runway had no difficulty, in otherwise very similar operating conditions. I have not done a detailed comparison of performance data though.

The airspeed required to obtain a climb in a 150 with full flaps will be very close to stall warning speed.

"Safe" is a very challenging thing to measure. Hence my pasting in the wording of the standard which would be applied to the 150, both back then, and now. The current standard's wording for the same requirement is:

523.77 Balked Landing

(a) [Each normal, utility, and aerobatic category reciprocating engine-powered aeroplane of 6,000 pounds or less maximum weight must be able to maintain a steady gradient of climb at sea level of at least 3.3 percent with:
(1) [Takeoff power on each engine;
(2) [The landing gear extended;
(3) [ The wing flaps in the landing position, except that if the flaps may safely be retracted in two seconds or less without loss of altitude and without sudden changes of angle of attack, they may be retracted; and
[(4) A climb speed equal to VREF, as defined in 523.73(a).

Vref would be about 1.3 times stalling speed in that configuration. Still pretty slow. The reference to skill still applies by a reference from a preceding paragraph. Thus the reference to airspeed for climb is the only difference between the two standards.

The earlier (previous post's) standard (CAR3) is the wording which would apply to the designs of both the 150 and the 152, though at the time that the 152 design was being validated by Cessna the newer wording would have been available (and for certain Cessna would know it well) so Cessna would have have compliance with the newer standard in their mind too.

The challenge is deciding what "without requiring.... exceptional skill on the part of the pilot" really means. That is where we are measuring "safe" as objectively as possible. The later standard does add one more condition, which reduces the demonstration pilot's opportunity to use his/her exceptional skill so as to show "safe" compliance of the aircraft. It is understood that the demonstration pilot's recent experience performing such flying, might give that pilot exceptional skills in that aircraft type. This is to be discounted by the pilot who performs the certification evaluation flying.

So how sloppy is that pilot to be to be fair to both sides? I know that I'm doing it very fairly when I pilot an aircraft type which I've never flown before, and show compliance with a requirement. If I've never flown that type before, I'm certain that I do not have exceptional skill in it. When Flying Cessnas, I have to be more cautious, as I've flown many types before. I try to be a tiny bit careless, and see if the plane bites me. If it's a trainer type, more careless.

During a Transport Canada approved flight test for the purpose of confirming the proper repair of a flying club 172, I purposefully took off with full flaps (only 30 in that model). I did re-land it before I left the runway. The instructor who accompanied me (for insurance reasons) was apparently very surprised this was possible at all. Later in that flight he asked me to demonstrate a roll to him. I would not. I later learned that he was the club safety officer, and second most "experienced" instructor. This was a larger club with more than 25 aircraft. I was reminded that instructors don't know everything.

During a recent flight test in a multi engine aircraft with external modifications, I simply could not make it climb as required (one only one engine) by the prevailing standard. I tried for more than 30 minutes. It did not pass the flight test.

So I return to my previous statement: Up high, in a safe environment, put the plane into slow flight, apply full power, and see if you can make it climb. If you cannot, question the airworthiness of the aircraft. It sounds like Lost Pilot Standing is already questioning the airworthiness of aircraft he flies, with terms such as "condition", "battered" and "abused". I assure you that these terms would not apply at all to the "typical" Canadian Cessna 150 I have seen and flown. Honestly, if the aircraft is not "airworthy" as measured by the standards of maintenance of the airframe, engine, and propeller manufacturer's respective publications, it might not perform as required by the design standards. This is one of the many very good reasons to assure that the aircraft you fly has been correctly maintained.

I would agree that a flying instructor who owns the flying school, and the Cessna 150 they are flying would generally be extended credit as a compotent pilot. As a compotent pilot, I presume that they are flying an aircraft which they have found to be airworthy. That said, with level terrain, I would wonder why that pilot could not accomplish something which the design standard says must be possible (and I have done). I am not in a position to speculate. Aircraft stick flaps, I would hope that intructors are training students what to do when it happens, so as to make the best use of the aircraft capabiltiy demonstrated during certification, which was required for exactly that circumstance.

"Safe", airborne in a battered and abused aircraft? Perhaps not so much...

Pilot DAR

[Old Fella]

Full Flap Go-Around

I regularly fly a very well maintained C150 Aerobat and I would not recommend anyone to attempt a go-around with full flap if it can possibly be avoided. With only 100 HP and the drag 40 degree flap generates climb is extremely limited. Wings level and land straight ahead would be my preference in almost every case. I have witnessed an unintentional attempt to go-around with full flap. The aircraft had to be flown level with incremental reduction of flap until sufficient airspeed to climb was attained. That was with about half full fuel tanks and two lightweight POB.