Tail Type vs

automan1223

Active Member
Joined
Nov 3, 2003
Messages
3,760
Location
Oriental, North Carolina
Aircraft
2p Tandem Air Command "Big Red"
Total Flight Time
250
Hello Everyone !

After 3 weekends down at the patch working with Maxie Wildes, flight testing and working out the bugs in my 2pl tandem subaru powered ej22. I have learned a few things and ask for some input. My machine has 2 tail surfaces. One is the lower HS with the winglets on the side as found on newer air command machines The second HS is attached to the tall rudder dominator type tall tail. Our problem in flight was that the nose did not want to drop to gain airspeed. I performed a hang test and everything was in spec so I reduced the angle of attack on the lower HS so it was flat with the keel it was attached to. While an improvement was observed, more was needed. More flight testing and photographs revealed need to reduce down force or angle of attack on the rudders HS. That was done and more improvement was observed.

Anyway I know there are many ships out there that fly with more than one hs but I have also heard comments that the tall tail with the HS can make the machine feel squirrely or odd. Since I dont have much experience with this I was wondering if there was a solid reason why the newer air command machines do not have a hs in the prop wash and only a rudder. Does a single rudder offer more yaw stability without the HS ? Any thoughts , etc appreciated.

Jonathan Weis
Oriental NC
 

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Re:Tail Type vs

MM it is my guess that the time and money to make a tall tail with HS is the reason for them. They might feel that the lower keel HS is good so why spend time and money to add more to it. I don't feel that my gyro flys squirrely or odd, and I use a tall tail with HS and a keel HS also. I think it flys great, rock solid as a matter of fact. I don't see how it would be better without the HS in the prop blast.
 
Re:Tail Type vs

Jonathan,

Can you tell us more about your observation? What do you mean, "the nose did not want to drop"? Are you talking about airspeed stability (i.e. the nose does no drop to maintain airspeed with less power)?

What kind of rotor blades are you using? Unstable rotors may cause a lack of airspeed stability. A stab with a negative angle of incidence should only improve your airspeed stability.

Is the rudder-mounted stab parallel with the engine?

Could you take a smart level with you on the next flight and then tell us what are the angles of the two stabs, in flight, at different airspeeds?

Personally, I think that your setup is the best of both worlds.

Udi-
 
Re:Tail Type vs

"Squirrelly or odd?" I can't speak to the ship on the picture 'cause of course I haven't flown it. But as for the regular Dominator with only the immersed HS...

I was able to fly it immediately upon climbing aboard. Its flight qualities were so appealing during my first-ever ride in one (Ernie's tandem, with Rusty Nance in the back seat babysitting) that I decided right then to get one.

It flies like a fixed-wing plane. That is, control pressures are distinct and in the right direction. You need back stick in turns (unlike unstable craft which require forward stick to keep from mushing). The craft drops its nose when power is cut (unstable craft raise their noses and do a mid-air flare if you don't catch them). It requires no stick corrections to hold airspeed in turbulence; the nose rises and falls as needed to hold speed. You just sit there.

The real proof of non-squirreliness, however, is how students have done. I turn the stick over to the student in the first five minutes of his/her first flight (at altitude, of course). Students can control this machine immediately. I had a 16-year-old lad who'd never even been in a small plane doing 360's ten minutes into a demo flight. No help from me other than talk. I have never had to intervene to stop PIO or any other tendency of the craft to get away from the newbie.

My only complaint about the Dominator's flight qualities is that it over-compensates for throttle changes. It's apt to slow down rather than speed up when you add throttle. Conversely, it speeds up when you cut power. The CG ought actually to be lowered a hair to more nearly coincide with the thrustline.

Jonathan, I think you're just going through the tuneup stage. When I first built the Gyrobee with HS, I guessed at 3 degrees negative incidence for the HS. It could have been a little less; 3 degrees produced the same kind of over-compensation the Dominator has. My revised HS will start with 2.5 deg.negative and work from there.
 
Re:Tail Type vs

Guys,

Could Jonathan have so much h-stab surface area that his machine weathervanes TOO much? That is, resists forward stick inputs?

I've heard that it's possible to have so much vertical stab area, relative to the vertical surface area ahead of the CG, that it becomes hard to crab during a crosswind approach. True?
 
Re:Tail Type vs

I do not see to much tall at all. OK If you are flying S/L and pull the power off what happens in your gyro. If you are holding the controls locked it might not lower the nose to hold trimed airspeed. If you have altitude and relax the controls it will fly at its trimed speed setting from that poind you can push for more pull for less speed. If you are doing this in crow hop you may not have time to feel the trim speed before you are at the end of the runway. I did my crow hops on a 6000 foot runway so I could get it up to speed let it fly and have time to set up to land. I think this let me feel the trim and setup for landings at a more relax mind set. It might just be me but crow hops are not really needed in a two place trainer if it is safe to fly.
Getting it above 500 feet or more and do long no power approches is better, don't even try to land just fly it down to say 10 feet power up and do it again. this way you can fell what it takes to hold off a cross wind and still have the runway ahead of you to use if needed not the end of a runway with trees in your face. This is how I got trained in a fixed wing and it worked fine. Yes back when you had to solo all the time do to no two place trainers that low crow hop was OK. Just my 5 cents
Brent
 
Re:Tail Type vs

[quote author=automan1223 link=board=6;threadid=749;start=#msg7959 date=1080665345]
Hello Everyone !

After 3 weekends down at the patch working with Maxie Wildes, flight testing and working out the bugs in my 2pl tandem subaru powered ej22. I have learned a few things and ask for some input. My machine has 2 tail surfaces. One is the lower HS with the winglets on the side as found on newer air command machines The second HS is attached to the tall rudder dominator type tall tail. Our problem in flight was that the nose did not want to drop to gain airspeed. I performed a hang test and everything was in spec so I reduced the angle of attack on the lower HS so it was flat with the keel it was attached to. While an improvement was observed, more was needed. More flight testing and photographs revealed need to reduce down force or angle of attack on the rudders HS. That was done and more improvement was observed.

Anyway I know there are many ships out there that fly with more than one hs but I have also heard comments that the tall tail with the HS can make the machine feel squirrely or odd. Since I dont have much experience with this I was wondering if there was a solid reason why the newer air command machines do not have a hs in the prop wash and only a rudder. Does a single rudder offer more yaw stability without the HS ? Any thoughts , etc appreciated.

Jonathan Weis
Oriental NC
[/quote]
 
Re:Tail Type vs

In reply to Paul W. P.: No, it is not possible to have too much HS power. As Jonathan is discovering, it's possible to have an HS that's out of trim, but that's a matter of adjusting the incidence, not shrinking the HS.

Unlike a fixed-wing plane, a gyro is controlled by tilting the wing with respect to the body. There's no need for the body to move in order for control to take place. Hence, it does not reduce the gyro's agility if the body is very firmly aligned with the airstream. In fact, it's helpful; the more the better.

The "unable to slip" airplane is a different case altogether. If the plane can't slip, it has too much fixed vertical fin area and not enough moveable area. In this case, we do face a tradeoff (or tension) between stability and controllability.
 
Re:Tail Type vs

Doug,

Thanks, as always. Makes sense...change the direction using the rotor and the relative wind will change, and the airframe will only follow more positively for having a large stab.
 
Re:Tail Type vs

Sorry its taken me so long to get back here.

Few points.

Shortened rotorblades down from 30' skywheels to 28' with new hub bar. This made things a whole lot better and the machine did fly considerably more to my imature / beginner control inputs.

Rotor speed went from 290-300 to 330-345. MUCH much better. I cant thank Maxie enough for a week of late nights and smoke and metal chips to get this done right.

Incidence on the hs was too agressive compared to other machines. I eyeballed it and did it wrong the first time, second and 3rd made much improvements.

With flat and level flight you would pull power and in would just drop in flat / pancake, also take off max v .... move the stick fwd and it would not drop, with shorter blades, and correct hs trim great improvment.

One note doug, be care full. With the pio thing cause I will admit here, I Started to do it and maxie had to yell and lock down the stick 2 separate times with the 30's ,

I also did something really stupid on one of my last runs and pulled power too close to the ground, and yanked the stick and started the bobble from left to right. not good because to add power to an already unstable situation could make things worse. There is no time to correct and with only 5 ft between you and the ground. My last landing was my worst. Good thing I have a beefy landing gear.

Funny thing you mention the dominator because the new owner of maxies old dominator refitted the machine with the a/c style tails and was actually the one to mention squirrely vs the tall tail as factory on the dom, I will call maxie and get his contact info. He had just started to warm up when I was leaving so I dont know the full story.

Jonathan
 
Re:Tail Type vs

Jonathan: Interesting info. I run 28' D-Ws on the Dominator. RRPM is about 315 two-up and 290 solo.

"Cut power too close to the ground." If you're on a landing approach, you should be at idle power already, certainly by the time you're down to five feet. One of my personal crusades is to get people to quit dragging gyros in under power. At least the latter part of the final approach, and preferably the whole approach, should be flown at idle. If you carry power on final, you risk landing short of the field if your engine packs it in -- and you'll also get accustomed to an unrealistic, stretched-out glide angle. You will NOT be happy when you have a real engine-out some day and the glide is twice as steep as you're used to!

Perhaps one of my students this season will succeed in getting the Dominator into PIO. An instructor has some latitude to let them to do this in a machine that's not PPO-prone. It's helpful to have them experience it firsthand under controlled conditions.

I hope Maxie comes to B-Days and brings his guitar.
 
Re:Tail Type vs

I know maxie is going,

my aformentioned flight fudge up was while doing a crow hop.

I also have to agree with Brent Brown and his take on crow hops and just learn to fly by flying. I also understand that each instructor has his or her own preferences and our lack of flying was due to other factors, machine was still in work out bug mode so Maxie wanted to keep things close to the runway.
 
Re:Tail Type vs

Doug said:

"One of my personal crusades is to get people to quit dragging gyros in under power. At least the latter part of the final approach, and preferably the whole approach, should be flown at idle."

Doug,

I think you wouldn't enjoy flying at my home airport very much.

On a nice day the traffic pattern is so damn packed with fixed wing traffic, that just to keep from getting rear ended in my gyro, I have to fly tight patterns (to maintain spacing ahead of traffic behind me), then make full power dive approaches to the runway darn near at VNE. Just prior to my intended point of landing (which is as close to a branching taxiway as possible)... THEN and only then do I pull the power back to idle while flaring and landing. About the time I'm clearing the runway, a fixed will have gained on me and is calling short final. A real zoo!

... And don't let me get started about the traffic jams on the taxiway leading to the runway! The worst time just is after lunch on a warm sunny day.

Thank god they don't allow touch-and-goes there or you'd never get a chance to take off.

Not a good place for low-time pilots.

On the bright side, everyone is friendly and it's a real family atmosphere... just very busy at times.

Take care,

John L.
 
Re:Tail Type vs

John, I guess a man's gotta do what a man's gotta do. If you have to do powered-up, jet-transport approaches to stay safe at a particular airport (and you choose to use said airport), then that's within an experienced pilot's exercise of judgment. I'd consider these to be departures from the basic technique, made necessary by circumstances.

What bothers me is that some folks aren't drilled on the basics. They are then in danger of landing in the ol' sewer lagoon (or worse) if they have a power failure.
 
Busy airports

Busy airports

Do as helicpters do....stay clear of the fixed-wing traffic. This may mean landing on the apron or the taxiway.
We have several helicopters operating at North Little Rock. None of them fly airplane patterns unless the pattern is empty.
Nobody has complained that the gyros operate like the helicopters in this regard.
I suppose it depends on the politics of the particular airport.
 
Airport Politics

Airport Politics

Hi Ron,

That's a tough one at this airport (flying a separate pattern).

The traffic pattern is always on one side of the airport due to strict noise restrictions (a real problem in the area), so that rules out automatically making an opposite pattern. Then using the only parallel taxiway doesn't work because it's the only one leading to the runway and is usually logged with ground traffic.

I've been thinking of meeting with the Airport Manager to discuss my concerns of being run over when traffic is heavy and suggest that maybe I should maybe avoid the faster traffic pattern altogether... just like the UL traffic that occasionally come in and out of the airport. They typically fly under and inside the pattern to get to the airport and then use a parallel turf strip that's on the traffic pattern side of the only runway. They use the asphalt runway only when completely clear and never fly the regular pattern.

Up until now I've avoided asking for any special treatment because I'm relatively new at the airport and I'm concerned about giving gyros a negative image by requiring special treatment. My hanger partner flies an RAF-2000 and his speed advantage (over my GyroBee) keeps him out of trouble. He's been at the airport for several years and complies strictly with the normal pattern.

For now I've just been dealing with it.

Regards,

John L.
 
John,

at my airport, I fly low and inside of the fixed-wing pattern.

Usually 300 feet, like the ultralights.
Helicopters use 500 feet.
Fixed-wing 1000 feet.

I usually takeoff and land on the taxiway too.

I'm sure that if you went to your airport manager asked to do something similar due to safety concerns, it wouldn't be a problem. It would show you as being a conscientious pilot.

And like Ron said...you are a rotorcraft. :)
 
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