Aggressive stall characteristics, C150

Vector said:
Please educate as you are clearly in depth
Click to expand...
The bushing into the rear wing spar attach on the fuselage has the bolt hole drilled off center.
This means that as you rotate that bushing, you change where in the fitting the attach bolt goes. This in turn changes the height of the aft spar attach point relative to the fuselage changing the angle of incidence. Let's say you have a heavy right wing. You would rotate the bushing in that wing so that the hole is as low as it will go. This will bring the trailing edge down, increasing that wing's angle of incidence and in theory making it less wing heavy. It's a real pain in the neck though as its a split bushing and the 2 halves are really hard to get to and you have to make sure you rotate them in synch.
On the flaps, your fault is in thinking that the flap track is what limits flap travel. It's not. Travel limits are set by limit switches and you should never use the full track as you'll start bending and breaking stuff if you run the flaps all the way to either end of the track. There is plenty of extra slot on bit the up and the down to allow for manufacturing and repair tolerances in individual flaps. The flap rigging I refer to is most often done by simply adjusting the rod end(s) on one flap to make it sit up or down farther than the other one. It's often used as a field shortcut around then painful process of adjusting wing incidence, however doing so can induce a roll and/or yaw when flaps are extended. It's not really an approved procedure on the cessnas, however it's THE way it's done on the Cherokee family (they also make it very easy by using opposite threaded rod ends at both ends of the flap pushrod, so you just rotate the pushrod to shorten or lengthen it. The Cherokee is my favorite airplane in the world to rig because it's so dang easy).
Hopefully this was all illuminating as it can be sort of hard to communicate the intricacies via typing on a phone.
If not, you're more than welcome to drop by my shop during annual season and I'll give you an in person demonstration.
 

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I'd give really thorough preflight. The kind that if it were you, the doctor would be putting on latex gloves and telling you "this may hurt a little bit."

If it came up clean, I'd chalk it up to a heavy wing or bad/improper rigging.
 
It's been about 8 years since I've flown a 150, but I remember the 150 wanting to drop a wing during stalls all the time.
 
Roger Roger said:
The bushing into the rear wing spar attach on the fuselage has the bolt hole drilled off center.
This means that as you rotate that bushing, you change where in the fitting the attach bolt goes. This in turn changes the height of the aft spar attach point relative to the fuselage changing the angle of incidence. Let's say you have a heavy right wing. You would rotate the bushing in that wing so that the hole is as low as it will go. This will bring the trailing edge down, increasing that wing's angle of incidence and in theory making it less wing heavy. It's a real pain in the neck though as its a split bushing and the 2 halves are really hard to get to and you have to make sure you rotate them in synch.
On the flaps, your fault is in thinking that the flap track is what limits flap travel. It's not. Travel limits are set by limit switches and you should never use the full track as you'll start bending and breaking stuff if you run the flaps all the way to either end of the track. There is plenty of extra slot on bit the up and the down to allow for manufacturing and repair tolerances in individual flaps. The flap rigging I refer to is most often done by simply adjusting the rod end(s) on one flap to make it sit up or down farther than the other one. It's often used as a field shortcut around then painful process of adjusting wing incidence, however doing so can induce a roll and/or yaw when flaps are extended. It's not really an approved procedure on the cessnas, however it's THE way it's done on the Cherokee family (they also make it very easy by using opposite threaded rod ends at both ends of the flap pushrod, so you just rotate the pushrod to shorten or lengthen it. The Cherokee is my favorite airplane in the world to rig because it's so dang easy).
Hopefully this was all illuminating as it can be sort of hard to communicate the intricacies via typing on a phone.
If not, you're more than welcome to drop by my shop during annual season and I'll give you an in person demonstration.
Click to expand...
I pulled out the service manual and found it. Surprisingly, my IA did not seem to care or bothered by this fact as we installed the wings on my C-172. I wonder how critical this is or how effective it is as the offset on the bushing is not significant. But then again, if the wing were heavy on one side, it would have been evident prior to stall and the pronounced wing drop wouldn't be a surprise. Again, I doubt this is the cause.

Never using the full track setting sounds like a maintenance/pilot hearsay. The manufacturer will conduct symmetric and asymmetric testing on the whole unit based on the class of the aircraft, so there really isn't any mechanical reason not to. Because the switch limits flap travel, then you shouldn't be able to go past the manufactured tolerance or am I missing something?
 
alaskadrifter said:
It's been about 8 years since I've flown a 150, but I remember the 150 wanting to drop a wing during stalls all the time.
Click to expand...
We did spins in them as pre-private pilots and I remember the wing dropping on the first few stalls. Makes it nice and easy to spin. Stays in to. Nothing like a 172.
 
Vector said:
I pulled out the service manual and found it. Surprisingly, my IA did not seem to care or bothered by this fact as we installed the wings on my C-172. I wonder how critical this is or how effective it is as the offset on the bushing is not significant. But then again, if the wing were heavy on one side, it would have been evident prior to stall and the pronounced wing drop wouldn't be a surprise. Again, I doubt this is the cause.

Never using the full track setting sounds like a maintenance/pilot hearsay. The manufacturer will conduct symmetric and asymmetric testing on the whole unit based on the class of the aircraft, so there really isn't any mechanical reason not to. Because the switch limits flap travel, then you shouldn't be able to go past the manufactured tolerance or am I missing something?
Click to expand...
Hey, I'm not an engineer, but of all the flap rigging procedures I've read, not one has involved "put the flap at the end of the track". It's always fair it to a rigging tool or some part of the wing, zero your protractor, then set the down limit. And there's always track left at the top and bottom-I repeat, if any electric flap system is set to run all the way to the end of its track it WILL break something or burn out the motor. I've seen it happen.
 
Roger Roger said:
Look at the leading edge of the 150 vs later 152s and 172s and you'll see what I'm talking about.
Click to expand...
I have a Right Wing for a C-150 in the garage as we speak and I am not seeing what you are talking about. I am pretty sure Cessna did not change airfoil from C-150 to C-152 regardless of the model year. I will go as far as saying all 100 series Cessna's have very similar asymmetric airfoils.
 
Vector said:
I have a Right Wing for a C-150 in the garage as we speak and I am not seeing what you are talking about. I am pretty sure Cessna did not change airfoil from C-150 to C-152 regardless of the model year. I will go as far as saying all 100 series Cessna's have very similar asymmetric airfoils.
Click to expand...
Ya, the entire Cessna 100 series with the exception of the Cardinal(177) uses a root NACA 2412 airfoil and either the NACA 2412 or 0012 at the tip. The 150 is a 0012 at the tip while the 172 is the 2412.
 
Roger Roger said:
Hey, I'm not an engineer, but of all the flap rigging procedures I've read, not one has involved "put the flap at the end of the track". It's always fair it to a rigging tool or some part of the wing, zero your protractor, then set the down limit. And there's always track left at the top and bottom-I repeat, if any electric flap system is set to run all the way to the end of its track it WILL break something or burn out the motor. I've seen it happen.
Click to expand...
Inboard trailing edge of the aileron in the Cessna case ;)

Sent from my XT1254 using Tapatalk
 
Vector said:
I pulled out the service manual and found it. Surprisingly, my IA did not seem to care or bothered by this fact as we installed the wings on my C-172. I wonder how critical this is or how effective it is as the offset on the bushing is not significant. But then again, if the wing were heavy on one side, it would have been evident prior to stall and the pronounced wing drop wouldn't be a surprise. Again, I doubt this is the cause.

Never using the full track setting sounds like a maintenance/pilot hearsay. The manufacturer will conduct symmetric and asymmetric testing on the whole unit based on the class of the aircraft, so there really isn't any mechanical reason not to. Because the switch limits flap travel, then you shouldn't be able to go past the manufactured tolerance or am I missing something?
Click to expand...

If it flies fine you're good, you may not have noticed but whenever we remove a wing we mark the bushing so that it gets reinstalled in the same orientation.


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z987k said:
Ya, the entire Cessna 100 series with the exception of the Cardinal(177) uses a root NACA 2412 airfoil and either the NACA 2412 or 0012 at the tip. The 150 is a 0012 at the tip while the 172 is the 2412.
Click to expand...
The 172 starting with the M model has a cuffed leading edge.

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