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150 performance

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Posted

My wife got a rude awakening to Cessna 150 T.O. performance on grass, max gross and relatively warm (75F) yesterday.

However the take off distances (ground run and 50' obstacle clearance) is almost twice what the (rather lacking) POH is predicting.

Have any of you have a similar experience (150L performance even poorer than the poor performance indicated in the table)?  Instructor (that was flying with her) indicates that this is typical of a 150.  Static run up is good (O-200) and 600 hrs SMO.  Actually amazed that these birds don't event have performance charts, just a cheezy interpolation table.

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Posted (edited)

My experience in this area is pretty extensive. As a manufacturer test pilot for 30 years I made a living flying demos to show flight manual performance. The manufacturers all have to stand by the performance, and demonstrate it to the FAA (or an internal FAA designated engineer) so it has to be close to the truth.

Most of the aircraft I have checked are pretty close, but since takeoff run is the sum of a dozen factors, it is the most easy measurement to get wrong. Think of the constituent parts: Prop condition and thrust, engine power production, rpm gauge accuracy, wing cleanliness, airspeed system calibration, tire pressure, surface hardness, grass depth. And with the slight climb angle, the biggest error could be the 50 reading, based on a cranky altimeter with 10' markings.

You can bet that the flight manual is based on everything being factory new and perfect, and so the performance is ideal. If the prop has a few dings and an eroded leading edge that has been sanded for a few years, it can be easily 5% less than factory thrust. Run down each factor with similar degradation, and it is not hard to get big errors.

I note that the dry grass run for a 150 at 1000', 75 degrees zero wind off dry grass would be 1660 feet over a 50' obstacle. Did it take them 3300 feet?

150takeoff.jpg

Edited by nlappos

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Posted

Yes

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Posted (edited)

I agree with all that Nick said about the test pilots.  You wont do any better than that.

I flew a 150 off of a 2600 ft concrete strip for years - In worst of Missouri summer conditions, with a passenger, never used more than half of runway.  100 foot Oak tree at one end, and power lines at other end.  There are several ways to do a takeoff.  The difference between solo takeoff and 2-persons is a lot, but not as much as in a Kitfox or Avid.

BTW:  Flew several 150s, and all of them would remain flying with ASI dropping from 40 to "0", just got to ease into AOA and power settings to get that slow flight maneuver.  EDMO

Edited by EDMO

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Posted

What I do find curious is that this L model has an obstacle clearance speed of 70 MPH while previous versions was 58.  Charts appear unchanged however.  Anyone know why this is?

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Posted

What I do find curious is that this L model has an obstacle clearance speed of 70 MPH while previous versions was 58.  Charts appear unchanged however.  Anyone know why this is?

The last one I flew was a K model - I have a manual somewhere, but don't remember model - Don't think I read one since about early 1960s.  EDMO

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Posted

When I was first getting my license I remember the 150 never performing all that great with 2 people. It's a old heavy plane with a small motor and seeing 400fpm on climb was normal. You gotta remember it's old , tired and meant for building hours and cruising around . Anyone who flies knows that if you put 2 adults in any plane fly off a grass strip with hot and humid conditions it's going to perform way more different. When I had my last biannual it was in a 152 and after flying my avid for a year the 152 felt like it was never getting off the ground but it did and at climb out it settled into it's 400 fpm climb . Old airplanes are like old cars , you cant expect them to perform like the new versions that are lighter and more efficient. Now for me if it took 3300ft to get off the ground with 2 people on board in grass I would've probably stopped my take off attempt about half way down the runway . I've never seen a 150 take that long even with full fuel and a couple heavy weights on board . Just my 2 cents but hell in real life it's probably only a 1/4 cent . Just remember in any airplane if a take off or landing doesn't feel right there's nothing wrong with aborting the attempt and trying again . 

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Posted (edited)

When I was first getting my license I remember the 150 never performing all that great with 2 people. It's a old heavy plane with a small motor and seeing 400fpm on climb was normal. You gotta remember it's old , tired and meant for building hours and cruising around . Anyone who flies knows that if you put 2 adults in any plane fly off a grass strip with hot and humid conditions it's going to perform way more different. When I had my last biannual it was in a 152 and after flying my avid for a year the 152 felt like it was never getting off the ground but it did and at climb out it settled into it's 400 fpm climb . Old airplanes are like old cars , you cant expect them to perform like the new versions that are lighter and more efficient. Now for me if it took 3300ft to get off the ground with 2 people on board in grass I would've probably stopped my take off attempt about half way down the runway . I've never seen a 150 take that long even with full fuel and a couple heavy weights on board . Just my 2 cents but hell in real life it's probably only a 1/4 cent . Just remember in any airplane if a take off or landing doesn't feel right there's nothing wrong with aborting the attempt and trying again . 

I agree with what you said about old airplanes, but just to correct the dialog:  I think they were talking about 3300 feet to clear 50 ft. obstacle and not the takeoff run.  But even that is far worse than what I have experienced in any of the 150 planes in our summer heat and humidity.   Not sure what their DA is, but most of our airports here are only about 130 to 150 msl.  EDMO

Edited by EDMO

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Posted

When I was first getting my license I remember the 150 never performing all that great with 2 people. It's a old heavy plane with a small motor and seeing 400fpm on climb was normal. You gotta remember it's old , tired and meant for building hours and cruising around . Anyone who flies knows that if you put 2 adults in any plane fly off a grass strip with hot and humid conditions it's going to perform way more different. When I had my last biannual it was in a 152 and after flying my avid for a year the 152 felt like it was never getting off the ground but it did and at climb out it settled into it's 400 fpm climb . Old airplanes are like old cars , you cant expect them to perform like the new versions that are lighter and more efficient. Now for me if it took 3300ft to get off the ground with 2 people on board in grass I would've probably stopped my take off attempt about half way down the runway . I've never seen a 150 take that long even with full fuel and a couple heavy weights on board . Just my 2 cents but hell in real life it's probably only a 1/4 cent . Just remember in any airplane if a take off or landing doesn't feel right there's nothing wrong with aborting the attempt and trying again . 

I agree with what you said about old airplanes, but just to correct the dialog:  I think they were talking about 3300 feet to clear 50 ft. obstacle and not the takeoff run.  But even that is far worse than what I have experienced in any of the 150 planes in our summer heat and humidity.   Not sure what their DA is, but most of our airports here are only about 130 to 150 msl.  EDMO

You are right 3300ft over a 50ft obstacle still seems like a long distance. I'm in Florida and at around 100 msl . With the hot air and humidity I still haven't flown a 150 that had that low of a performance. 

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Posted (edited)

When I was first getting my license I remember the 150 never performing all that great with 2 people. It's a old heavy plane with a small motor and seeing 400fpm on climb was normal. You gotta remember it's old , tired and meant for building hours and cruising around . Anyone who flies knows that if you put 2 adults in any plane fly off a grass strip with hot and humid conditions it's going to perform way more different. When I had my last biannual it was in a 152 and after flying my avid for a year the 152 felt like it was never getting off the ground but it did and at climb out it settled into it's 400 fpm climb . Old airplanes are like old cars , you cant expect them to perform like the new versions that are lighter and more efficient. Now for me if it took 3300ft to get off the ground with 2 people on board in grass I would've probably stopped my take off attempt about half way down the runway . I've never seen a 150 take that long even with full fuel and a couple heavy weights on board . Just my 2 cents but hell in real life it's probably only a 1/4 cent . Just remember in any airplane if a take off or landing doesn't feel right there's nothing wrong with aborting the attempt and trying again . 

I agree with what you said about old airplanes, but just to correct the dialog:  I think they were talking about 3300 feet to clear 50 ft. obstacle and not the takeoff run.  But even that is far worse than what I have experienced in any of the 150 planes in our summer heat and humidity.   Not sure what their DA is, but most of our airports here are only about 130 to 150 msl.  EDMO

You are right 3300ft over a 50ft obstacle still seems like a long distance. I'm in Florida and at around 100 msl . With the hot air and humidity I still haven't flown a 150 that had that low of a performance. 

The "experts" can argue all day, but holding in ground effect to get a little more speed will let you grab a little altitude quicker, rather than just mushing along trying to climb too soon.   "Cropduster takeoff"!   It don't matter what altitude you might have one minute out with best angle of climb if you cant clear an obstacle at the end of the runway.   EDMO

Edited by EDMO
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Posted

There's a guy at Zephyrhills that does a lot of touch n gos with his champ . Sometimes he holds it in ground effect and sometimes he pops it up . When stays in ground effect a little longer and gets his speed up he definitely climbs out better.

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Posted

I tried to find the video, but wasn't able to.  There was one of those Hitler videos with the English subtitles where he says all kinds of different goofy things.  In the one I looked for, he was arguing for the merits of the zoom climb on takeoff.  JImChuk

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Posted

150 Performance is an Oxymoron.

 

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Posted (edited)

I tried to find the video, but wasn't able to.  There was one of those Hitler videos with the English subtitles where he says all kinds of different goofy things.  In the one I looked for, he was arguing for the merits of the zoom climb on takeoff.  JImChuk

I think the Adolph video was the one I watched to learn that takeoff!   V2 takeoff was better tho!   ;<)    But it could have been one hot summer day when the Navion pilot I was riding with left the ground effect too slow and we mushed into the trees at the end of the runway and clipped some leaves as we barely made it over them - That got my attention!   EDMO

Edited by EDMO
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