A-D-Aero

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Hi Guys, anyone flying a H-9 Giant Corsair and having a shimmie in flight. As if the rudder were wagging? Does it at slow speed and high speed. Sometimes it wables quit a bit. Went thru all the control linkage and such. I did add additional supports on the rudder pushrods. It seems to have made an improvement, but still does it some.
Any thoughts on this specific plane?
Thanks,

Mpizpilot

My Feedback: (45)

That's the corsair tail wag. Many do it, not just the H9

David Eichstedt

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Yep. Endemic to Corsairs of all sizes.

Lifer

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A gyro on the rudder will minimize the problem.

A-D-Aero

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Thanks everyone for the feedback. Guess I won't worry too much about it. Just fly and have fun.

77chickenhawk

I think its cool. The real ones do it to...

Chris Nicastro

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Having riden back seat in a modified F4U-5NL out of Kalispell MT at well over 350knts I can tell you I didnt detect any tail wag in fact it was really smooth and pleasant. Loops and rolls are quite anti climactic actually.

Model Corsairs do have a characteristic wag but I have not personally seen the H9 Corsair do it yet. I have seen it on my TFGS. As I get a friends H9 more dialed in I think it may show up but we'll see.

Just to compare notes whats your CG set at?

Chris Nicastro

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Im in the back seat during this fly by!!

https://youtu.be/512yhAFDMeg

cessnaflyer54

My Feedback: (68)

My H-9 Corsair 60 has the tail wag and no big deal. Fly it and enjoy. Chris, I have my CG at 4 7/8's from the leading edge.
Seems to work for me. No ballooning with half or full flaps.

A-D-Aero

My Feedback: (7)

Chris, thanks for the reply. That ride you had in the full scale had to be so cool. My CG is at 5" back with gear down and about 5.25" with gear up. I think it is still a little nose heavy though. I may play with it a little.
Thanks,
doug

A-D-Aero

My Feedback: (7)

One more post. I test flew a buddies H-9 Corsair tonight. It too has the same wag. Now we just fly and let em wag.

gsoav8r

My Feedback: (6)

My TF Corsair doesnt tail wag when strait and level. Just when coming out of turns and especially diving turns. Wind direction seems to be a factor as well.
Ive found that coordinating turns with a touch of rudder eliminates most of the wag I used the see. Cheers.

philakapd

I know it's not scale, but have you considered installing a flying wire kit between the vertical and horizontal stabilizers?

RCFlyerDan

My Feedback: (54)

Wind direction never matters. Turbulence is different and can cause issues. Aerodynamics 101.

Todd D

My Feedback: (51)

I seen a lot of models with the Corsair waggle. Not uncommon as most have said.

I've also hear that the full scale had the waggle as well but that was corrected using a mechanical type gyro. All hear say so I can't confirm the gyro information.

Hot Rod Todd

My Feedback: (1)

The sensitivity to turbulence in a Corsair is due to the Dihedral of the wing tips. What you're experiencing is called the "Dutch Roll." If you want to know more about it there's an excellent article by Model aircraft designer David Anderson at http://www.mnbigbirds.com/images/PDF...hedral_Art.pdf

Lifer

My Feedback: (1)

In my experience, the waggle is caused by insufficient vertical stabilizer area and that the vertical stabilizer is too far forward. Other models of the era had the same problem when the planes were converted to bubble canopies. The solution was a dorsal fin, but that would look weird on a Corsair.

A gyro would cure the problem or one can accept it as a scale characteristic and live with it.

camss69

My Feedback: (46)

I know it's not the same plane, but I have had a bunch of World Models P-51's and all of them have a tail wag. It seems worse when flying into a headwind, I don't know why they do it, I just fly them and they've always been ok.

RCFlyerDan

My Feedback: (54)

Again, Some of you R/C pilots don't understand "Relative Wind". Headwind, tailwind or crosswind is relate to the planes movement over the Earth. Has nothing to do with the airplane going through the fluid of air that produces lift.

Relative wind is created by movement of an airfoil through the air. As an example, consider a person sitting in an automobile on a no-wind day with a hand extended out the window. There is no airflow about the hand since the automobile is not moving. However, if the automobile is driven at 50 miles per hour, the air will flow under and over the hand at 50 miles per hour. A relative wind has been created by moving the hand through the air. Relative wind flows in the opposite direction that the hand is moving. The velocity of airflow around the hand in motion is the hand's airspeed.
In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil. It is opposite to the direction of movement of the aircraft or airfoil relative to the atmosphere. Close to any point on the surface of an aircraft or airfoil, the air is moving parallel to the surface; but at a great distance from the aircraft or airfoil the movement of the air can be represented by a single vector. This vector is the relative wind or the free stream velocity vector.[SUP][1][/SUP]
The angle between the chord line of an airfoil and the relative wind defines the angle of attack. The relative wind is of great importance to pilots because exceeding the critical angle of attack will result in a stall, regardless of airspeed.

camss69

My Feedback: (46)

You feel better now Dan? I don't think I mentioned anything about movement over the earth or the fluid of air, or angle of attack or vectors of air or anything else mentioned in your post other than maybe misusing the term "headwind".. Which I'm still not sure I used incorrectly.

When I'm flying in the direction the wind is coming from the tail shakes more.

This RC pilot thanks you for the informative post, but the tail still shakes no matter how I describe it and your post really didn't help explain why.

RCFlyerDan

My Feedback: (54)

Yes, Thank You I do feel better knowing that I tried to help educate those who didn't spend their life time learning about aviation and the total misuse of proper terms. As a retired Professional Jet Capt and teacher of aviation for more then 35 years of my life, I just hate those who misuse terms in aviation, thinking they understand. YET, it is now obvious you don't understand the definition of relative wind.

To help answer your question of why some planes "tail wag" or have yaw issues, is due to design. It is widely known that all swept wing jets have some sort of yaw issue. Thus, jets have yaw dampers, or some other sort of gyro system to alleviate the yaw. As far as WWII planes, since it is prior to my time period of aviation, just poor design and the characteristics of the plane. On R/C could be the design defect from the original design, so that simple R/C pilots as yourself can fly a complex plane. If the plane is truly designed to scale specs., which most ARF's and kits are NOT, then I doubt you could fly it as an R/C pilot. The other strong possibility, has to do with poor installation of the rudder, too much gap between the rudder and vertical stab, weak and sloppy servo gears, cheap and poor linkages. BUT, since you seem to know it all, just go on and stuff your head in the sand, that you are NOT willing to learn from someone who has spent their life in aviation.

Lifer

My Feedback: (1)

Dan,

I get the impression you spend a lot of time alone.....

RCFlyerDan

My Feedback: (54)

No

camss69

My Feedback: (46)

Lol... Wow!

I went ahead and did a little research.. I used the app on my phone labeled "Dictionary" and looked up the word "Headwind". You don't have to look it up Dan I'll post it here...

1. a wind opposed to the course of a moving object, especially an aircraft or other vehicle (opposed to tailwind )

So getting back to my original post... It looks like I may have used the term "Headwind" correctly after all. This makes me wonder why you felt the need for your original reply, which again, wasn't all that helpful when it came to explaining why the tail was wagging OR correcting my use of the word "headwind".

I think this thread is about the H9 Corsair, not Jets so I'm a little confused why you're talking about swept wing jets. Since WWII aircraft are before your time as you mentioned above, you say "it's probably just poor design or a characteristic of the plane"... I think that's already been mentioned in the thread previously so you didn't really "help" there either Dan.

When it comes to me or any other competent RC pilot being able to fly an RC airplane that is a scale design vs a full scale pilot attempting to fly an RC plane that is a scale design I'll take the RC Pilot any day of the week.

I also find it rather ridiculous you accuse me as claiming to "know it all" given your two posts above. I also said in my original post "I don't know why they do it".

Lastly a bit of advice if you have all that knowledge in your head and you want to help people then maybe it would help if you figured out a way to not make yourself sound like an ass. If this is what you call helping, I'll get my help elsewhere.

I have the H9 Corsair, apparently the tail shakes on it. I was interested to know why and if they all do it, that's why I'm in this thread. Do you have the Corsair Dan and if so does the tail shake?

RCFlyerDan

My Feedback: (54)

[QUOTE=camss69;12080542]Lol... Wow!

I went ahead and did a little research.. I used the app on my phone labeled "Dictionary" and looked up the word "Headwind". You don't have to look it up Dan I'll post it here...

1. a wind opposed to the course of a moving object, especially an aircraft or other vehicle (opposed to tailwind )

1. Thank you for posting this definition! What do you define as "course" - not coarse? Course over what? Have you ever seen your Corsair go in reverse in flight? Maybe a tail slide in a stall turn? From your description, this is a tail wind. Truly not. Why do you think it takes 7+ or so hours in a jet to go from NYC to LAX? Verses 5.5 or so hours on a good day to go from LAX to NYC? Called headwinds and tailwinds of the jet stream.
   
   Again, Thank you for looking up the definition. But, thanks to our wonder school system, the understanding of the meanings of words are overlooked.
   
   As you quoted:
   
   "1. a wind opposed to the COURSE OF A MOVING OBJECT, especially an aircraft or other vehicle."
   
   

[h=1]course /kɔrs, koʊrs/ [/h]

noun 1. a direction or route taken or to be taken.

2. the path, route, or channel along which anything moves: the course of a stream.


3. advance or progression in a particular direction; forward or onward movement.




5. the track, ground, water, etc., on which a race is run, sailed, etc.: One runner fell halfway around the course.

In other wards, the plane/vehicle must travel over a surface to have a headwind or tailwind.

The way I best explain this to my students, is if they are boaters. Truly hope you and others on this forum have some boating experience. A boat on a flat non-current lake sets its throttle to, lets say for the example, 2000 rpm. And, again for the example, at 2000 rpm, the boat moves forward at 20 mph. Now, without the affects of drag in a turn, lets say the boat does a 360 turn. Without the affects of drag, the boat continues the 360 circle at 20 mph. Can you visualize and accept that proven theory? If so, move the boat to a river, and the river is moving at 10mph in whatever direction, normally towards the sea. Put the same boat on the river going against the 10mph current at 2000rpm and it should give you a speedometer speed of 20mph? Correct? But, due to the "current or headwind in our situation", the boat is moving through the fluid of water at 20mph, and yet is only traveling 10mph across the ground. Turn the boat around, and it is still going 20mph through the fluid of water, and the ground speed becomes 30mph.

If there is no wind on that day, then the plane at a set rpm in level flight, is going to give a certain mph. Head and tailwinds only matter for ground travel. This is also another reason that normally, a pilot takes off into the wind. This is to reduce the take off roll and tire speed. Due to some planes and tires have max tire speeds. The plane still rotates at it's normal take off speed of flight.

"it's probably just poor design or a characteristic of the plane"... I think that's already been mentioned in the thread previously so you didn't really "help" there either Dan



As far as "Characteristic of the plane" ----I would say I agree with that guy too! Smart guy!


Do you have the Corsair Dan and if so for the tail shake?[/

Yes, I have built, not an ARF, a Ziroli Corsair, and currently building a Ziroli P-51 from plans. I am mostly into turbine jets for my hobby, as you can see in my profile and pictures. I had the Corsair about 15 years ago, and seemed to remember a wiggle. I have been flying a turbine F-18, F-16 and Panther as my scale jets, and my sports jets, and starting to get back into the prop war birds.