Cessna 150L -> Cessna 150M; Is it 4 knots faster? If so, why?

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docmirror

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Title says it all. Presume I am Cessna stoopid - cuz I am Cessna stoopid. Always like the 150, but I don't know squat about them. The book say the M model is 4 knots faster. Don't know why. :confused:
 
The marketing department said they needed more speed, so the printers changed the numbers. :D
The words "speed" and "Cessna 150" shouldn't be used in the same sentence, unless it leads to a punch line. :D

docmirror said:
Title says it all. Presume I am Cessna stoopid - cuz I am Cessna stoopid. Always like the 150, but I don't know squat about them. The book say the M model is 4 knots faster. Don't know why. :confused:
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N747JB said:
The marketing department said they needed more speed, so the printers changed the numbers. :D
The words "speed" and "Cessna 150" shouldn't be used in the same sentence, unless it leads to a punch line. :D
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Hey, I can get 120 knots in my 150.....in a steep descent. About the only thing that makes a 150 go faster is by reducing drag by putting on the wheel pants.
 
What about the flap and gap seals?

Seriously, the two plane models look identical to me.
 
Magic dust. Best way to make a 150/152 faster is to sell it and buy a Cherokee.
 
Put wheels pants on and do a 150/150hp swap
 
I know the L was faster than the K by a little bit thanks to a new airfoil, but I wasn't aware of any changes between the L and M to gain speed.
 
I've purchased the STC to do the gap seals on my Socata Tampico. The word from people who have done it is that it does almost nothing for speed. Maybe a knot or two. It DOES help with rate of climb. Most who have installed it on the TB9 agree that it adds 100-150 FPM to the climb rate.

In a way it does make you fly faster. Less time climbing at the lower climb speed means that your average speed for any given trip goes up...
 
Mike5250 said:
Do you know what speeds it will get with 150hp?
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Not worth the effort IMO. The only reason a bigger engine would make sense would be for towing gliders. Otherwise it will be by far cheaper to just buy a faster airplane.
 
Adding HP rarely results in greater speeds, although adding almost 40 HP might! Extra HP shows up in improved climb perfomance. Speed improvements come from drag reduction and you are (mostly) stuck with what came from the engineer's design.
 
JB1842 said:
I've looked at the gap seals. Not sure if it's worth the cost.
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Gap seals help with control crispness. We had all of them on our Pathfinder (Cherokee 235) and they also seemed to help a bit with improved stabilator authority. If they added any speed, it was minor.

For added speed, you need airframe enhancements, like wing/fuselage fairings, and wheel pants. It also helps to remove protrusions, like jelly jar beacon lights.

The mods on our Pathfinder cost the original owner $20K, and netted maybe 12 knots. On a 150, there would be no way to justify the expense.
 
Jay Honeck said:
Gap seals help with control crispness. We had all of them on our Pathfinder (Cherokee 235) and they also seemed to help a bit with improved stabilator authority. If they added any speed, it was minor.

For added speed, you need airframe enhancements, like wing/fuselage fairings, and wheel pants. It also helps to remove protrusions, like jelly jar beacon lights.

The mods on our Pathfinder cost the original owner $20K, and netted maybe 12 knots. On a 150, there would be no way to justify the expense.
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That's my feeling as well. Rather spend the money on new radios, interior, and gas.
 
Well, we're far enough in to this thread now to declare it dead. I guess the book just lied better for the M than it did for the L model. Or, maybe they changed the parameters of the flight test for cruise speed.

It's a sad fact that even with a conforming engine and prop, and a plane in rig that it won't meet book value.
 
docmirror said:
Well, we're far enough in to this thread now to declare it dead. I guess the book just lied better for the M than it did for the L model. Or, maybe they changed the parameters of the flight test for cruise speed.

It's a sad fact that even with a conforming engine and prop, and a plane in rig that it won't meet book value.
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Someone hit the wrong button on the typewriter.
 
docmirror said:
Seriously, the two plane models look identical to me.
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Cessna goosed the advertised cruise speeds (which were always suspect anyway) on several models when they swapped those draggy, squared-off longboat wheel fairings for the more rounded fairings that cover more of the tires (trap doors needed to put air in the tires), and brake covers. The 150 got those in '74. If no wheel fairings, no difference. The 150M might even be a tad slower with the bigger vertical tail.

cessna_150l_1971.jpg


cessna_150m_1975.jpg


Grum.Man said:
I know the L was faster than the K by a little bit thanks to a new airfoil, but I wasn't aware of any changes between the L and M to gain speed.
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What new airfoil? The 150/152 and 207 were the only strutted Cessnas that never got the recontoured leading edge. They flight-tested a 150 with the new airfoil, but for some reason a 2-turn spin now took 13 turns to recover. So they just left the 150 airfoil well enough alone and never bothered to investigate it further. As to the 207, there was not enough volume to justify the flight test investment.
 
All Cessna speed mods on almost all models average out to $1000/knot. And half of them don't work. :)
 
Mike5250 said:
Do you know what speeds it will get with 150hp?
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No idea, but I'd imagine that about the most you could do to squeeze speed out.

The guys I know that have done it were for climb performance and one who made it into a sea plane.
 
Pilawt said:
Cessna goosed the advertised cruise speeds (which were always suspect anyway) on several models when they swapped those draggy, squared-off longboat wheel fairings for the more rounded fairings that cover more of the tires (trap doors needed to put air in the tires), and brake covers. The 150 got those in '74. If no wheel fairings, no difference. The 150M might even be a tad slower with the bigger vertical tail.
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I see it! Also note that some of the 150L models have a tapered up wing tip, and some have the slight droop tip. Don't know what's going on there, it doesn't seem to follow any year.

So, ideally for a speedy 150 I would want a taildragger L with the droop tips, and later M wheel pants. If I'm lucky, it would have flap and gap seals already installed.

Thanks!
 
I know a retired dentist who just put a 180 hp in his 150. Already has long range tip tanks. My buddy flew with him two weeks ago and said it was weird cruising mid-way through the yellow arc. But the real difference was they climbed at full gross, 1000 FPM all the way up to 5000'.

Now, the Sparrowhawk conversion on the 152 will get you speed, but we're not talking 152s.
 
IIRC the 150hp/150 would go a couple knots faster than a 160hp/172
 
I've flown the 150HP 150/152 variant (can't remember which one it was). Doesn't go any faster but it sure climbs like a bat out of hell.

Usually putting a big engine on the same airframe yields similar results. It takes a lot of HP to overcome the additional drag of the higher speed. You usually can get better results casting an eye towards reducing the drag.

You've still got a plane that gets bird strikes from the rear :)
 
docmirror said:
I see it! Also note that some of the 150L models have a tapered up wing tip, and some have the slight droop tip. Don't know what's going on there, it doesn't seem to follow any year.
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The factory droop tips (cosmetic only; no discernable effect on handling or performance) came with the "Commuter" option package and were optional on others. There are a few aftermarket tips out there, too.
 
The bestus cheapest way to make a 600cc motorcycle faster is to sell it buy a 1000cc motorcycle. I'd bet it is the same with cars, trucks, boats and aircraft. :)
 
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etemplet said:
The bestus cheapest way to make a 600cc motorcycle faster is to sell it buy a 1000cc motorcycle. I'd bet it is the same with cars, trucks, boats and aircraft. :)
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Kind of, until you get in the Experimental world where you can modify at will. The key to speed in a plane is drag profile, and as with any performance endeavor, there is an exponential curve to increase in speed and cost/effort to attain it.

Since power required goes up by the square of the speed, the obvious thing is to approach it from the drag end. High wing loading is the result, but you pay for it in runway performance or complexity and weight in extraordinary high lift devices which cost power, power costs fuel which costs more weight...

So that's why we operate mostly in the speed range we do, all in all it's the most efficient and reasonable profile to operate in without getting into really sketchy landing scenarios. The first time you put a race wing Midget Mustang on at 90, you feel extremely vulnerable.
 
The only way I know of to increase the IAS of a Cessna 150 is to put a hole in the static line to create a static leak. :rofl:
 
John Collins said:
The only way I know of to increase the IAS of a Cessna 150 is to put a hole in the static line to create a static leak. :rofl:
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Lets say a 150 uses 90hp to go 90kts, when you give it 145hp you should gain about 6.5kts.
 
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