Is this the yaw report you guys are all worked up about? I looked for the
Cafe challenge report on the CT and this was all that came up other than numbers.
This was an 06 airplane??
Read the August 9th 08 entry. Peter seemed pretty surprised also.
He's been around a long time and flown some weird stuff. He's also one of the judges for NASA and Cafe on handling qualities. Pretty unbiased stuff.
http://www.melmoth2.com/texts/Progress.htm
just to compare with our airplane. We had a 3 blade neuform prop, no brake disk fairings. No nose wheel strut fairings just a pant. Smaller vertical tail, smaller stabilator tab. Not sure what tire size is on the test airplane shown.
Yet from his description it flies similarly.
Could it be there are differences in the rudder molds? Some are ok, others are not. I don't know if they have multiple molds at FD.
Years ago Cessna moved the tooling for the 195. There was a large batch of airplanes slower than the rest till the error in the tooling was found. Too much stabilizer negative incidence was being put in.
We had a Beaver one time which was slower than all the rest. Turned out to be the stabilizer was reskinned and had a twist. Drilling all rivets out and jigging while installing new skins cured it. Just the small amount of slop in each rivet hole was enough.
Depending on how the composite is trimmed and amount of glue in joints the CT profiles might vary enough to cause problems. I know just a little water droplets frozen under the wing from washing on a cold day make trouble. Could even be door fit, gear leg fairing angle or.....
There has to be a reason why some of you say it flies great and others (like myself) had trouble. It goes way beyond pilot experience.
question in all this CT mess
Moderator: drseti
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CharlieTango
- Posts: 1000
- Joined: Sat Jun 10, 2006 10:04 am
- Location: Mammoth Lakes, California
you can't put that much into his description,
I found the CT to be the least pleasant of the three in flight. I was surprised, in fact, that an airplane with its handling qualities could even come to market. It is directionally unstable; if you floor a rudder pedal the ball goes over the the edge of the inclinometer and just stays there; if you roll without rudder the effect is the same.
not quite fair, he claims the ct is directionally [yaw] unstable yet from his description it is either neutrally or positively stable. you can't tell for sure cause he doesn't say if he released the floored rudder pedal. in neither case is he describing instability. the ball going to the edge is what should happen when you floor the rudder pedal.
next he describes adverse yaw, he is right the ct does demonstrate adverse yaw and you have to coordinate the turn.
I found the CT to be the least pleasant of the three in flight. I was surprised, in fact, that an airplane with its handling qualities could even come to market. It is directionally unstable; if you floor a rudder pedal the ball goes over the the edge of the inclinometer and just stays there; if you roll without rudder the effect is the same.
not quite fair, he claims the ct is directionally [yaw] unstable yet from his description it is either neutrally or positively stable. you can't tell for sure cause he doesn't say if he released the floored rudder pedal. in neither case is he describing instability. the ball going to the edge is what should happen when you floor the rudder pedal.
next he describes adverse yaw, he is right the ct does demonstrate adverse yaw and you have to coordinate the turn.
Fair is not the issue. There is something about these airplanes that makes people who have flown a lot of different airplanes be caught by surprise.
I have a theory. Just from observing other airplanes around.
None have rudders with a teardrop shaped airfoil. All taper from the hinge line straight to the Trailing edge of the rudder.
Maybe they need to make a rudder with no airfoil shape. Just a straight taper from hinge aft.
If the CT is close to laminar flow then the aft section of the rudder is probably in turbulent flow. If there is any rudder deflection then the side of the rudder that pushes outside the boundary layer will suddenly see accellerated flow. This region of transition between laminar and turbulent flow will move aft on the rudder with more deflection. As it sucks over to the side the downwash ( or sidewash in this case) will also push the rudder over to more deflection.
The X air had the same problems but it was due to the Trailing edge tubes on the rudder being large diameter. As the rudder deflected the rounded tube shape made lift pulling the surface over farther.
RV-4's have the same problem if the aileron trailing edge bend is made to large. Aileron snatch during rolls.
All this comes back to the differences between airplanes. Years ago there was a guy with a Dragonfly tandem wing laminar flow airplane. He painted spanwise stripes on the leading edge of the wings. The canard flew so badly that he went back and sanded the very tiny ridge off and then it flew well.
Could it be the CT paint schemes on the vertical fins are to blame? If they are vinyl stick on stripes there would be a very large ridge. That would explain the differences between otherwise identical airplanes.
Sailplane guys use tape and models use turbulator tapes to change the surface smoothness and flow.
Like I said before. very tiny water droplets on the bottom of the wing and flap made a airframe vibration and stick shake.
This is not poking fun or picking sides. I just want to know why some of these airplanes fly good and others bad. Without you guys flying every one out there to see for yourself you don't know what you're talking about either. Arguing won't make any difference unless you all line your airplanes up and fly them all.
Suck it up and have FD do some testing. usually problems are very simple in the end. They did a bunch of wind tunnel time a while back. The answers may or may not be in there.
I have a theory. Just from observing other airplanes around.
None have rudders with a teardrop shaped airfoil. All taper from the hinge line straight to the Trailing edge of the rudder.
Maybe they need to make a rudder with no airfoil shape. Just a straight taper from hinge aft.
If the CT is close to laminar flow then the aft section of the rudder is probably in turbulent flow. If there is any rudder deflection then the side of the rudder that pushes outside the boundary layer will suddenly see accellerated flow. This region of transition between laminar and turbulent flow will move aft on the rudder with more deflection. As it sucks over to the side the downwash ( or sidewash in this case) will also push the rudder over to more deflection.
The X air had the same problems but it was due to the Trailing edge tubes on the rudder being large diameter. As the rudder deflected the rounded tube shape made lift pulling the surface over farther.
RV-4's have the same problem if the aileron trailing edge bend is made to large. Aileron snatch during rolls.
All this comes back to the differences between airplanes. Years ago there was a guy with a Dragonfly tandem wing laminar flow airplane. He painted spanwise stripes on the leading edge of the wings. The canard flew so badly that he went back and sanded the very tiny ridge off and then it flew well.
Could it be the CT paint schemes on the vertical fins are to blame? If they are vinyl stick on stripes there would be a very large ridge. That would explain the differences between otherwise identical airplanes.
Sailplane guys use tape and models use turbulator tapes to change the surface smoothness and flow.
Like I said before. very tiny water droplets on the bottom of the wing and flap made a airframe vibration and stick shake.
This is not poking fun or picking sides. I just want to know why some of these airplanes fly good and others bad. Without you guys flying every one out there to see for yourself you don't know what you're talking about either. Arguing won't make any difference unless you all line your airplanes up and fly them all.
Suck it up and have FD do some testing. usually problems are very simple in the end. They did a bunch of wind tunnel time a while back. The answers may or may not be in there.
some good some bad
Cub Flyer,
Could you please point me in the direction of where there is "factual" information that "some fly good" and "some fly bad". And please give me the numbers you must have access to as well. It would be nice to have the customers names to so I can call and verify the information.
Thanks in advance for those figures...
Roger H
Could you please point me in the direction of where there is "factual" information that "some fly good" and "some fly bad". And please give me the numbers you must have access to as well. It would be nice to have the customers names to so I can call and verify the information.
Thanks in advance for those figures...
Roger H
Sure.
Bad. N126CT Owned by Boyd Strickland. That is the one I was involved with flying and giving dual from 3-06 to 9-06
N460CT
N460CT was owned by John Calla who is a CT dealer.
mailto:[email protected]
I flew that airplane once from 76N to Woodstock Conn. We were comparing airplanes all the way.
N126CT the yaw tendency was a little stronger and I believe was the first with the rudder springs installed at Woodstock after I complained.
John had flown both airplanes also. He did not fly N126CT after the springs were installed.
N460CT was an identical 05 except paint scheme and normal wheels.
both were destroyed in landing accidents, loss of control.
Ok was the long wing CT demo airplane I flew a little bit at Franklin PA July 05. I don't remember it doing anything strange in flight.
John flew that airplane also.
In my opinion I would have rather had the pedal pull than those springs.
Obviously your airplane and the one Charlie Tango has are ok. He tried simply pushing the pedals and the nose returns pointing forward.
Totally different than the reactions I and others have found. That is not a handling qualities opinion but a reproducable problem.
Charlie Tango says he flew an 05 once that had the pedal pull. Add that airframe to the list.
This was before the centering springs
I had never heard of the 06 doing that until I read the Pete Garrison blog report. Especially since it should have had the springs. While not detailed, he flew four other LSA designs that day and the CT is the only one notable in handling quirks.
He has no reason to be biased and was put in that position just for that.
You have an experienced designer / tester saying in a note to nobody in particular on a blog what he honestly thought.
I'm not trying to provoke you guys but there are no other airplanes that I know of which have such different reactions between pilots. Which means either some CT airframes have different characteristics or pilots love to argue about CT's. Most have no reason to find fault so I'm convinced it's some difference in tooling, surfaces, or rigging between airplanes.
Bad. N126CT Owned by Boyd Strickland. That is the one I was involved with flying and giving dual from 3-06 to 9-06
N460CT
N460CT was owned by John Calla who is a CT dealer.
mailto:[email protected]
I flew that airplane once from 76N to Woodstock Conn. We were comparing airplanes all the way.
N126CT the yaw tendency was a little stronger and I believe was the first with the rudder springs installed at Woodstock after I complained.
John had flown both airplanes also. He did not fly N126CT after the springs were installed.
N460CT was an identical 05 except paint scheme and normal wheels.
both were destroyed in landing accidents, loss of control.
Ok was the long wing CT demo airplane I flew a little bit at Franklin PA July 05. I don't remember it doing anything strange in flight.
John flew that airplane also.
In my opinion I would have rather had the pedal pull than those springs.
Obviously your airplane and the one Charlie Tango has are ok. He tried simply pushing the pedals and the nose returns pointing forward.
Totally different than the reactions I and others have found. That is not a handling qualities opinion but a reproducable problem.
Charlie Tango says he flew an 05 once that had the pedal pull. Add that airframe to the list.
This was before the centering springs
I had never heard of the 06 doing that until I read the Pete Garrison blog report. Especially since it should have had the springs. While not detailed, he flew four other LSA designs that day and the CT is the only one notable in handling quirks.
He has no reason to be biased and was put in that position just for that.
You have an experienced designer / tester saying in a note to nobody in particular on a blog what he honestly thought.
I'm not trying to provoke you guys but there are no other airplanes that I know of which have such different reactions between pilots. Which means either some CT airframes have different characteristics or pilots love to argue about CT's. Most have no reason to find fault so I'm convinced it's some difference in tooling, surfaces, or rigging between airplanes.
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CharlieTango
- Posts: 1000
- Joined: Sat Jun 10, 2006 10:04 am
- Location: Mammoth Lakes, California
charlie,
years ago when we were having a similar discussion, the one where you went back and deleted all of your posts, i went to tom dunham, who at that time had flown 40+ ctsw's and asked how many bad flying birds there where.
in his experience the number was zero. i think you are focused on a quirk that went away witht the 05 model / tail. i also think if you understand how to fly the 05 ( or 06 - 08 ) you will see they mostly fly well. following your posts it sounds as though a good flying ct is rare and i have seen only good flying ct's.
don't forget the loss of control incident that totaled your bird came after a period of beating it up, there was something wrong and you guys continued till you killed it. didn't your partner loose his certificate? that would mean that the faa faulted him, but now years later it is time to blame the bird again.
i have 2 theory's that are pretty simple; 1: the egg shape and short nose produces a bird that is very happy to slip and it can be hard to detect. this might be the basis for the new tail design and the old rudders deflecting.
2: the flaps and flaperons at 30 and 40 degrees and throttle closed needs a 20 degree nose down attitude to maintain 1.3 Vso, a thee point attitude means a stall, even a level attitude will produce a stall / rapid sink. you need some stored energy or an open throttle to flair with flaps. i have seen high time guys blow landings in my bird and it is always the same thing, too much flaps, too little throttle, and stalling with the wheels a few feet in the air.
a friend just got a new to him, old 206 with a stol kit. the ailerons droop with the flaps until full flaps and then the ailerons come back. this would be a great feature for the ctsw at 40 degrees.
in closing i agree the blog post is honest but the words still describe neutral stability ( at worst ) as instability. agreed he didn't like the handling, neither did i in my first 1/2 hour until i learned not to overcontroll.
years ago when we were having a similar discussion, the one where you went back and deleted all of your posts, i went to tom dunham, who at that time had flown 40+ ctsw's and asked how many bad flying birds there where.
in his experience the number was zero. i think you are focused on a quirk that went away witht the 05 model / tail. i also think if you understand how to fly the 05 ( or 06 - 08 ) you will see they mostly fly well. following your posts it sounds as though a good flying ct is rare and i have seen only good flying ct's.
don't forget the loss of control incident that totaled your bird came after a period of beating it up, there was something wrong and you guys continued till you killed it. didn't your partner loose his certificate? that would mean that the faa faulted him, but now years later it is time to blame the bird again.
i have 2 theory's that are pretty simple; 1: the egg shape and short nose produces a bird that is very happy to slip and it can be hard to detect. this might be the basis for the new tail design and the old rudders deflecting.
2: the flaps and flaperons at 30 and 40 degrees and throttle closed needs a 20 degree nose down attitude to maintain 1.3 Vso, a thee point attitude means a stall, even a level attitude will produce a stall / rapid sink. you need some stored energy or an open throttle to flair with flaps. i have seen high time guys blow landings in my bird and it is always the same thing, too much flaps, too little throttle, and stalling with the wheels a few feet in the air.
a friend just got a new to him, old 206 with a stol kit. the ailerons droop with the flaps until full flaps and then the ailerons come back. this would be a great feature for the ctsw at 40 degrees.
in closing i agree the blog post is honest but the words still describe neutral stability ( at worst ) as instability. agreed he didn't like the handling, neither did i in my first 1/2 hour until i learned not to overcontroll.
I went back and deleted those when the FAA came for Boyds certificate while he was still laying in the hospital.
I was not sure what if any legal trouble would happen so I figured it would be better with that not out there.
The SP talk hacker incident would have erased them anyway.
The airplane flew that way on my first flight the day it was delivered.
Parts we damaged were: Lower steel axle tube to gear leg connectors bent both sides at different times, bent nosewheel rim.
That's all we broke. The nosewheel was a very light spun hegar wheel which was not designed for the gross weight of the CT. This wheel was supplied as part of the tundra gear package.
We purchased a updated machined aluminum wheel from FD and we had no further nose wheel damage.
The lower axle tubes have been the cause of several wheel separation incidents and I believe were also improved.
these were all simple bolt on fixes and we never found any cracking or damage on the upper gear leg areas or engine mount.
The abuse we gave the airplane was no worse than any standard trainer would go through in a normal week.
We never damaged any wing tips, prop, tail or fairings. I still have the wheel pants if anyone is interested.
The Piper Vagabond is very short nose, side by side and also egg shaped to some degree. The wing to tail distance is shorter than the CT.
It slips like crazy and will recover instantly on removing your foot pressure from the pedal with no oscillation. With a similar size tail and rudder as the 05 CT.
My point to all this is FD should be able to make it handle nicely without any quirks and not lose performance, add weight or add springs but they do not for some reason.
Probably expense in changing molds.
I have flown Robertson STOL Cessna 185,206 and 207. They are different than the standard in aileron feel. You can also feel a slight yaw sometimes when the flaps and ailerons come down. CT was similar.
I'd think to reduce weight, cost and improve feel FD would eliminate the flaperons. or offer as an option. Also it would give more effective washout with the flaps down.
For the change in performance and maintenance with the Robertson 206 I'd rather install the Sportsman droop leading edge and VG kit.
Thats what we have installed on the infrared survey 206. I fly at 65 mph indicated all night long maneuvering aggressively with 20 deg flaps and a 50 lb camera hanging off the left strut. Stall warning blows so much it the horn overheats and it changes tone.
Lots of slow flight practice.
I was not sure what if any legal trouble would happen so I figured it would be better with that not out there.
The SP talk hacker incident would have erased them anyway.
The airplane flew that way on my first flight the day it was delivered.
Parts we damaged were: Lower steel axle tube to gear leg connectors bent both sides at different times, bent nosewheel rim.
That's all we broke. The nosewheel was a very light spun hegar wheel which was not designed for the gross weight of the CT. This wheel was supplied as part of the tundra gear package.
We purchased a updated machined aluminum wheel from FD and we had no further nose wheel damage.
The lower axle tubes have been the cause of several wheel separation incidents and I believe were also improved.
these were all simple bolt on fixes and we never found any cracking or damage on the upper gear leg areas or engine mount.
The abuse we gave the airplane was no worse than any standard trainer would go through in a normal week.
We never damaged any wing tips, prop, tail or fairings. I still have the wheel pants if anyone is interested.
The Piper Vagabond is very short nose, side by side and also egg shaped to some degree. The wing to tail distance is shorter than the CT.
It slips like crazy and will recover instantly on removing your foot pressure from the pedal with no oscillation. With a similar size tail and rudder as the 05 CT.
My point to all this is FD should be able to make it handle nicely without any quirks and not lose performance, add weight or add springs but they do not for some reason.
Probably expense in changing molds.
I have flown Robertson STOL Cessna 185,206 and 207. They are different than the standard in aileron feel. You can also feel a slight yaw sometimes when the flaps and ailerons come down. CT was similar.
I'd think to reduce weight, cost and improve feel FD would eliminate the flaperons. or offer as an option. Also it would give more effective washout with the flaps down.
For the change in performance and maintenance with the Robertson 206 I'd rather install the Sportsman droop leading edge and VG kit.
Thats what we have installed on the infrared survey 206. I fly at 65 mph indicated all night long maneuvering aggressively with 20 deg flaps and a 50 lb camera hanging off the left strut. Stall warning blows so much it the horn overheats and it changes tone.
Lots of slow flight practice.
The CT was not too sensitive. In fact I though the ailerons were too heavy and should be lighter.
I like airplanes that respond instantly and have light controls.
I'm not trying to talk people out of buying one. They should just get some time in the seat before ordering to see if it fits.
The yaw problems we were having I believed to be isolated to some of the small tail 05 airplane until I read Pete Garrisons report.
Somewhere there should be a more detailed report from CAFE on all the airplanes tested that day.
He and others would have flown all the airplanes there that day.
It would be nice to have a copy. I have not flown the Pipstrel or Lambada airplanes.
Magazine reviews are hard to get any real info out of. They review their advertisers airplanes.
The NASA / CAFE review is as close to a non biased review and evaluation we can get. It would also put this whole argument to rest.
For a while Sport aviation did reviews like this. The CAFE people were involved. Then they wrote a bad review about some odd pusher airplane and the reviews stopped.
EAA was also built a homebuilt design review, evaluation test center in the early 80s near Burlington Wisconsin. That quietly was forgotten after the auto gas STC testing days.
I like airplanes that respond instantly and have light controls.
I'm not trying to talk people out of buying one. They should just get some time in the seat before ordering to see if it fits.
The yaw problems we were having I believed to be isolated to some of the small tail 05 airplane until I read Pete Garrisons report.
Somewhere there should be a more detailed report from CAFE on all the airplanes tested that day.
He and others would have flown all the airplanes there that day.
It would be nice to have a copy. I have not flown the Pipstrel or Lambada airplanes.
Magazine reviews are hard to get any real info out of. They review their advertisers airplanes.
The NASA / CAFE review is as close to a non biased review and evaluation we can get. It would also put this whole argument to rest.
For a while Sport aviation did reviews like this. The CAFE people were involved. Then they wrote a bad review about some odd pusher airplane and the reviews stopped.
EAA was also built a homebuilt design review, evaluation test center in the early 80s near Burlington Wisconsin. That quietly was forgotten after the auto gas STC testing days.
Ok. Last idea on this.
Feb 1973 EAA Sport Aviation. Tells the story of a little airplane called the MacDonald S-20. VW powered and simple.
He wanted light ailerons and built them with Frieze balances.
Similar to the CT rudder leading edge.
The ailerons when deflected beyond 1/2 way would suck to full deflection (aileron snatch)
To fix this they installed small wedges (about 8" by 1/4") on each aileron top and trimmed their length to get the desired feel.
Since the rudder is a single surface then it would need a wedge on each side.
The Pilatus PC-12 has a short T shaped extrusion on the rudder trailing edge to do a similar function.
This would eliminate the rudder pull over on the few airplanes which this occurs without centering springs or larger vertical fin. Less weight and less parts. Better control feel.
You would need to rebalance the rudder and a full test procedure but it is an idea to pass along to FD.
If the airplane passed the positive stability yaw test outlined in the US LSA regs, which I was told it did with the small tail. then this must be islotated to a few airplanes. If that is the case then the larger vertical tail and centering springs were not needed.
For FD to see if it works would only take a wedge of hard foam and some clear tape. Should be easy enough.
Feb 1973 EAA Sport Aviation. Tells the story of a little airplane called the MacDonald S-20. VW powered and simple.
He wanted light ailerons and built them with Frieze balances.
Similar to the CT rudder leading edge.
The ailerons when deflected beyond 1/2 way would suck to full deflection (aileron snatch)
To fix this they installed small wedges (about 8" by 1/4") on each aileron top and trimmed their length to get the desired feel.
Since the rudder is a single surface then it would need a wedge on each side.
The Pilatus PC-12 has a short T shaped extrusion on the rudder trailing edge to do a similar function.
This would eliminate the rudder pull over on the few airplanes which this occurs without centering springs or larger vertical fin. Less weight and less parts. Better control feel.
You would need to rebalance the rudder and a full test procedure but it is an idea to pass along to FD.
If the airplane passed the positive stability yaw test outlined in the US LSA regs, which I was told it did with the small tail. then this must be islotated to a few airplanes. If that is the case then the larger vertical tail and centering springs were not needed.
For FD to see if it works would only take a wedge of hard foam and some clear tape. Should be easy enough.