datorres88
Daniel Torres
- Joined
- Feb 15, 2015
- Messages
- 1,296
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There have been a couple of threads regarding rigging on here lately so I thought I would continue to beat a dead horse (because I don't have the guts to go near a live horse ;-) )....
So after 15 years I decided to really check the rigging of my flaps and ailerons. About 12 years ago I brought the plane to a shop for an annual and asked them to check the rigging because I felt the plane was slow. They basically said it looked fine, it's a Cherokee, what are you expecting to get from it.
Years later, after installing a couple of speed mods (Hoerner tips, Speed Pants, Nose strut fairing, gaps seals were installed when I bought the plane) I decided to pay attention to several posts I have seen here and else where and actually check the rigging for myself using easily made rigging tools.
Well, a quick check revealed that my flaps and ailerons were negative. Not just negative, but very negative. Now I know there are some out there that advocate for negative rigging as a speed mod (I don't subscribe to this for PA28's since I think the neutral is about as clean a wing as you can get). But when you are 3 or 4 degrees negative, the control surfaces start to act like spoilers.
So I needed to change my rod end bearings for my ailerons. This is normally a simple thing, but I have gap seals so I had to drill out those rivets first to access the rod ends. I could not adjust the rigging without doing this because after 47 years, the rod would not turn on the bell crank end and I was not about to disassemble the bell crank. So changing the bearings gave an opportunity to adjust the rigging by simply rotating one end.
After getting everything to neutral I took the plane for a quick test flight.
What a difference! The first thing I noticed was how nicely she jumped off the runway. Well, I suppose that without the ailerons acting as spoilers and pushing the wing down that better take off performance should not be surprising. But how would this affect speed? Wouldn't lowering the surfaces from negative to neutral result in more induced drag? Well, apparently not (which goes to show that neutral is about right for this wing). At 2,700 feet I was getting about 121 KTAS (based on my ASI with the TAS wheel) using a power setting that my JPI 830 says was 68% (assuming my HP constant is set properly) and a fuel flow of about 8.8 GPH! According to the book I shouldn't see those speeds for at least another 1,000 feet DA, and only then at 75% power and 10.1 GPH. All this and the plane flew nice and straight hands off!
Next thing for me to do is to rig the rudder and nose wheel which I think are out of alignment.
We all know the most Cherokees out there are notoriously mis-rigged and most A&P's have no clue as to how to correctly rig these planes, despite the very simple procedures in the maintenance manual. (Please A&P's, don't get offended by this, it is just my experience that whenever I ask A&P's that I have encountered about rigging I usually get a deer in the headlights response. If you are reading this and you know more than those guys, then that explains why you are on this forum giving useful advice.) This is one success story.
So after 15 years I decided to really check the rigging of my flaps and ailerons. About 12 years ago I brought the plane to a shop for an annual and asked them to check the rigging because I felt the plane was slow. They basically said it looked fine, it's a Cherokee, what are you expecting to get from it.
Years later, after installing a couple of speed mods (Hoerner tips, Speed Pants, Nose strut fairing, gaps seals were installed when I bought the plane) I decided to pay attention to several posts I have seen here and else where and actually check the rigging for myself using easily made rigging tools.
Well, a quick check revealed that my flaps and ailerons were negative. Not just negative, but very negative. Now I know there are some out there that advocate for negative rigging as a speed mod (I don't subscribe to this for PA28's since I think the neutral is about as clean a wing as you can get). But when you are 3 or 4 degrees negative, the control surfaces start to act like spoilers.
So I needed to change my rod end bearings for my ailerons. This is normally a simple thing, but I have gap seals so I had to drill out those rivets first to access the rod ends. I could not adjust the rigging without doing this because after 47 years, the rod would not turn on the bell crank end and I was not about to disassemble the bell crank. So changing the bearings gave an opportunity to adjust the rigging by simply rotating one end.
After getting everything to neutral I took the plane for a quick test flight.
What a difference! The first thing I noticed was how nicely she jumped off the runway. Well, I suppose that without the ailerons acting as spoilers and pushing the wing down that better take off performance should not be surprising. But how would this affect speed? Wouldn't lowering the surfaces from negative to neutral result in more induced drag? Well, apparently not (which goes to show that neutral is about right for this wing). At 2,700 feet I was getting about 121 KTAS (based on my ASI with the TAS wheel) using a power setting that my JPI 830 says was 68% (assuming my HP constant is set properly) and a fuel flow of about 8.8 GPH! According to the book I shouldn't see those speeds for at least another 1,000 feet DA, and only then at 75% power and 10.1 GPH. All this and the plane flew nice and straight hands off!
Next thing for me to do is to rig the rudder and nose wheel which I think are out of alignment.
We all know the most Cherokees out there are notoriously mis-rigged and most A&P's have no clue as to how to correctly rig these planes, despite the very simple procedures in the maintenance manual. (Please A&P's, don't get offended by this, it is just my experience that whenever I ask A&P's that I have encountered about rigging I usually get a deer in the headlights response. If you are reading this and you know more than those guys, then that explains why you are on this forum giving useful advice.) This is one success story.
