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gyromike
09-15-2004, 11:52 AM
First Dominator Flight

At the Bastrop Fly-In on 9/11/04, Chuck Irby offered to let me take up his 618-powered Dominator. So Sunday morning I went for my first Dominator ride.

To begin with, it's a long-legged bird, so I couldn't just plop into the seat like my Bensen, but Chuck showed me how to climb in with minimal effort, and I'm only 5' 8" tall. Entering from the right side of the machine, I put my left hand on the right side of the seat, and my right hand on the dash. Placing my right foot on the heel plate under the rudders, I was able to just hop up into the seat without a problem. So, it turns out that you don't have to be an acrobat to get in.

The 12-gallon seat was form-fitting and very comfortable, and I was able to easily reach all of the controls, but the control stick was a little far away for me (more on that later). Chuck explained what all the switches and controls were for, including the EIS Engine Instumentation System, which is compact and user-friendly.

After a thumbs-up, Chuck pulled the rope and she came to life. Being equipped with a clutch on the gearbox, the engine just idled as I sat there not moving. I advanced the throttle to around 2600 RPM's, and the prop started turning, and I was able to then engage the prerotator and start rolling out to the taxiway. I wasn't used to steering with heel brakes as my Bensen has unitized steering, so I found myself pushing the rudder pedals and wondering why the machine wasn't turning. Then I would remember the heel brakes. I'm sure that anyone watching me taxi out was wondering why the rudder was flapping all over the place!

The suspension on the machine was not too soft, but I remember overhearing Ernie at Bensen Days saying that "It ain't a go-kart! Taxi at walking speeds!". I did, and had no feeling of body roll.

Once lined up on the runway, I locked the brakes, and spooled up the blades to around 170 RRPM before beginning the takeoff roll. The blades came up to speed quickly and the machine rocked back on it's tailwheel. I got it balanced on the mains as I applied power, and it lifted off. I mentioned before that the stick was a little far away, but it may be also that I am used to my pump handle on the Bensen. The Dominator came off the runway with the nose a little high, and I had to push more than I was used to to drop the nose some. Anyway, I got used to it pretty quickly. With the 618 at full power, I climbed a a pretty brisk rate. It has plenty of power.

(Edit: Also on takeoff, there was no tendency to yaw. It just goes straight with no dancing on the pedals.)

I climbed up to around 500 feet before trying any maneuvers other than gentle turns. The wind was blowing around 5 mph at that altitude, and there was some turbulence coming off of the treeline on the east side of the runway. As I flew through this turbulence, the gyro was rock steady. Absolutely no pitching, rolling, or yawing. I was pretty comfortable right off the bat, and found myself looking for turbulence to fly through.

I put the machine into steeper and steeper banks, and it just went where I pointed it. No overshoot or lag in the controls.

In level flight I glanced down at the ASI, and realized that I was zipping along at 70 MPH. It didn't feel like I was going that fast, maybe because of the pod. It was stable at all speeds even at 90 MPH with me "stirring the pot".

I had flown in a modified Bensen once that had a tall-tail and immersed flat-plate stab, but I didn't like the feel of it. The tail wasn't mass balanced and had no anti-servo tab, so there wasn't much feedback in the pedals. That Bensen also had a Sportcopter cab on it, and the rudder didn't really have enough authority for that much area ahead of the CG. You couldn't take your feet off of the pedals.

Not so on the Dominator. I could have left my feet on the floor for all the good they were doing me. I would jab the left rudder and release, and the gyro would just recenter itself with little or no oscillation. Same to the right. I did it several times and the result was always the same.

After this I decided to try an approach to landing. I set up an approach and started down to the runway pulling the power back enough for a shallow descent and flew it down to the surface. I was a little leery of misjudging my height, so I just leveled off right above the runway and held it off until the tailwheel touched before reduucing power and pulling back on the stick. Worked pretty good, so I took off and did it again. This time I pulled back the power far enough that the prop clutch disengaged, and immediately felt the drag of the windmilling prop and a quickly steepening descent. So I added power to re-engage the clutch and shallow out my descent, and flew it on again.

Later, I flew again with Rod Reed following on my Bensen, and I kept cutting across his rotor wash to feel the turbulence, and again no surprises. I just went through with no corrections required. On my last landing, I plopped it on a little harder than the previous times, but the gear just soaked it up like it was nothing. I hadn't worked up the nerve for a Stop-N-Drop yet! :)

Taxiing back to the ramp was more of the same rudder dancing until I remembered to use the heel brakes.

The machine performed better than I had expected, even though I expected it to perform as advertised. I really like the tail, and it's changed my mind about tall tails. I had considered making a tall tail for my Bensen, but with a seperate vertical and rudder. This configuration certainly seems to be the best route though. Light and effective.

Also the airfoil shaped stab in the propwash was rock-solid. No oscillations in pitch.

I would have to give the Dominator 2 thumbs up!

http://www.rotaryforum.com/forum/attachment.php?attachmentid=4805

barnstorm2
09-15-2004, 12:53 PM
This is an excellent and well written review. Thanks Mike!

Screw
09-15-2004, 02:04 PM
Screw-In

I enjoyed fying Ron's Dominator at SX days. :D They are sweet long legged machines.

Screw-Out

Friendly
09-15-2004, 03:23 PM
Great review Mike, it sounds like you really gave it some good testing. That more than just flying someones gyro. I like your comparison to the Benson. We could use more articles like this to help newbies make up their mind.

GyroRon
09-15-2004, 04:35 PM
Good Review Mike, Makes me want to rush out and get a Dominator.



Oh thats right, I already got one! ;)

Seriously, I believe if every gyro pilot had a chance to fly a Dominator and did so with a open mind, I can't see many that afterwards wouldn't want to go out and get one for themselves as well. It is night and day different to alot of gyros I have flown. To be fair I am sure that there is other gyros that fly as well or better than a Dominator, A Monarch would likely be one along with the Aircommand Elites to name another. But compaired to alot of other machines.... You guys don't know what your missing!

gyromike
09-15-2004, 05:00 PM
Glad ya'll liked the review.

After reading all of the opinions of Dominator pilots and reading the merits of CLT and immersed stabs, I expected it to fly well.

I just wasn't expecting to be as comfortable with it so quickly. Also the 618 rocks!

Most importantly...I looked good sitting in it! :D

It's really got me thinking of what my next project might be. If not a genuine Dominator, it will certainly have the positive attributes like CLT and Immersed stab.

gyromike
09-15-2004, 05:29 PM
Ron,

I also flew an Air Command Elite at the fly-in, but it didn't have a tall tail. It had the standard full flying rudder with the small stabilizers. It would yaw around with power changes at low speeds.

It needs a tall tail and a better stabilizer. Never having flown the Air Command Elite tail group, I can't comment on the effectiveness of their setup. But it has to help with the yaw instability.

If it were mine, I know what I would put on it. :D

GyroRon
09-15-2004, 05:39 PM
Ron,

I also flew an Air Command Elite at the fly-in, but it didn't have a tall tail. It had the standard full flying rudder with the small stabilizers. It would yaw around with power changes at low speeds.

It needs a tall tail and a better stabilizer. Never having flown the Air Command Elite tail group, I can't comment on the effectiveness of their setup. But it has to help with the yaw instability.

If it were mine, I know what I would put on it. :D

Mike that observation explains why I got into such a pissing match with Heron a few months ago over the Monarch and Butterflys. I have never flown either, but with the short tails there IS going to be yaw to deal with - not a big deal, but why have it when you don't have to? - with a tall tail you don't.

I still need to put a trim spring on the left side of my rotorhead to counter the weight of the heavy hydro pre rotator unit on the right side, BUT I feel sure that once I do that and get my normal trim spring set up perfectly for 65 mph cruise, I Feel that I could take my feet off the pedals, and hands off the stick, and let the machine fly itself for as long as I cared to let it. AND in just about any weather!

I have not flown Chucks machine, but would expect it to fly like most Dominators. I have yet to find two dominators that flew exactly the same though, some flew better than others. If you ever get the chance to fly it, the best one I have yet to fly was the little 503 powered Ultrawhite Ernie had at Bensen Days for sale. Tom C.'s Hirth powered Dom was probably number two, with my new White one and Scott Lewis' 912S single place coming in for a tie for the number 3 spot.

I forgot to mention another really nice flying Dominator I had the pleasure of flying... Russ Kings nice Yellow 582 powered Single place. I believe it was probably right up there with Toms Hirth machine. Very Smooth. Both Toms and Russ' and Scott Lewis all have Slider rotorheads and all had smooth blades from what I can remember.

PW_Plack
09-15-2004, 05:43 PM
Everybody watching your tail-flopping said, "Wow, that guy's really serious about safety during his run-up. Look at him double-checking that rudder!"

ben
09-16-2004, 01:14 PM
hey gents,
i'm building a tall tail like on the dominator what does the anti-servo tab do on it?

pwendell
09-16-2004, 05:02 PM
From what I understand the anti servo tab does two things. 1. It centers the tail when you're not pressing on the pedals, and 2. it provides force feedback through the pedals.

ben
09-16-2004, 05:10 PM
pwendell, is it fixed or is it aloud to flop in the breeze?

pwendell
09-16-2004, 05:31 PM
It moves as the all-flying tail moves, but in the opposite direction. In other words, if you give right rudder, the trailing edge of the tab moves to the left and resists the tail's trailing edge move to the right. When you release pressure the tab will automatically pull the tail back to the center and center itself. At least that is how I understand it. I don't actually fly with one. The Sparrowhawk use an anti-servo tab, but the modified RAF that I've been flying uses springs to center the tail and provide resistance.

scottessex
09-17-2004, 02:26 AM
The anti-serveo tail tab, is a thing of beauty in its simplicity, I did not have a an anti-servo tab on my flying rudder, no problem, except, you could not take your foot off the left pedal, With an anti-servo tab you can fly with no feet on the pedas as it is self centering.

ben
09-17-2004, 04:12 AM
scott,
the anti-serveo tail tab, does it just hinge on the end of the tail?

GyroRon
09-17-2004, 04:22 AM
Ben, yes it does. Imagine a small flap attached to the rear of the tail at the bottom. It is hinged and can move independant of the rudder left and right. It has a extention that goes from IT'S bottom FORWARDS back under the rudder itself that is about a inch think with a notch cut into it that allows a bolt to go though it to hold it to the top of the keel just ahead of the tailwheel. The purpose of the notch and bolt is to make the servo tab go to the left when the rudder is pushed to the right, to help center the rudder and allow feedback with this kind of tail.

I will look for my best picture, but I don't think I have a good one...

scottessex
09-17-2004, 04:54 AM
Yes it just hinges on the tail, and has a piece of flat sheet with a slot running to the keel, to provide a pivot aft of the rudder pivot. That way the tab turns in the opposite direction of the rudder, providing feedback, and self centering.
I have a good picture of the mechanism at the house, I can post it this evening.

gyromike
09-17-2004, 06:18 AM
Doesn't it turn in the same direction as the rudder, but at a greater angle?

If it turned in the opposite direction, it would magnify the rudder input.

Ben here is about the best picture I have of one, and I also drew it out.
Hope it helps.

scottessex
09-17-2004, 06:26 AM
You are right Mike, I wasn't able to look at my pictures, and it was early, thanks for correcting me!

Okay Mike, you fly a Bensen and you flew chuck's dominator. Big difference in the tail? as far as yaw control, holding right/left rudder?

Chuck Irby
09-17-2004, 08:04 AM
Wow!, great sketches, Mike!

ben
09-17-2004, 10:05 AM
gyromike, thanks great picture. how long is the peice of sheet metal an d how long is the slot thanks.
scott like to see your pic too thanks guys ben

gyromike
09-17-2004, 10:42 AM
Okay Mike, you fly a Bensen and you flew chuck's dominator. Big difference in the tail? as far as yaw control, holding right/left rudder?

Scott,

Yaw control on my Bensen is not a real chore since I am spinning a 52" dia. prop. Short tails on a 60" or larger prop have a much more difficult time.

My Bensen has a 10º right offset in the rudder when my pedals are in the neutral position. My vertical stab is parallel to the keel. I could use just a touch more offset, or I could bend the back of the rudder (it has a small trim tab built into it), as I have to hold just a little right rudder in level cruise flight. Not much though. If I take my feet off the pedals it yaws slightly to the left, and a little right pedal pressure, or the weight of my foot, brings me back to coordinated flight.

The Dominator seemed to just track straight down the runway on takeoff, and I just used the rudder to keep it over the centerline of the runway.

Chuck had a small yaw string on it, but being right in front of the windshield and low to the pod, it was flopping around pretty good. However, I could fel the wind equally on both shoulders so it seemed to stay in trim when I slid my feet down from the pedals.

Power changes did not affect the gyro in yaw, and neither did the turbulence. Hit the juice and it would accelerate straight forward and start climbing.

As I wrote above, I started jabbing lightly at the rudder pedal to see if the gyro would return to coordinated flight, and it did so every time with little to no oscillation. Even when I gave the pedal a good push.

I really like that the trim tab recentered the rudder without any input from the pilot. The airfoil shape has plenty of control authority, both in the yaw and pitch axes. Having the horizontal stab in the prop wash really dampened any lag in the controls, no matter how much I horsed it around.

I experienced the same effect in Terry Eiland's Sparrowhawk conversion last December. It used centering springs to recenter the rudder, but the effect was the same even the the wind was howling with plenty of mechanical turbulence. A hard gust from the right would yaw the gyro to the right a little, and then it would straighten itself out to the relative wind.

I had been of the opinion that a tail (tall or otherwise) needed a fixed vertical stab with seperate rudder to be really effective, but the two above examples have changed my mind.

gyromike
09-17-2004, 10:45 AM
gyromike, thanks great picture. how long is the peice of sheet metal an d how long is the slot thanks.
scott like to see your pic too thanks guys ben

Ben,

Glad you and Chuck liked the sketches. It's one of my many useless talents. :)

I don't know how long the piece of metal is, nor how long is the slot.
Sorry.

ben
09-17-2004, 12:45 PM
ron,
like to thank ya for your response

scottessex
09-17-2004, 01:07 PM
Here is your picture :) Hopefully you will be able to see it good enough to see how it works.

ben
09-17-2004, 01:11 PM
i have an air-command clt with a ea81 and a hirth redrive on it. the engine was built by colorado rebuilt. its been deck .015, hi comp piston and a cam put in it. they say its 100 horse.i took the pod off and put on just the instr. pod you ve seen. with a10 mph wind in my face i had no problem crow hopping. she yaw some but not to bad. the next time i tried it was 90 degrees out and no wind. i wound the motor out to 5300rpm on a 62 inch prop and when she broke ground she yaw real hard thats why i'm hoping that by building a tall tail will calm that down some.

ben
09-17-2004, 01:49 PM
scott,
great picture thanks again

GyroRon
09-17-2004, 03:24 PM
I think it will make a HUGE improvement Ben.

Udi
09-17-2004, 05:49 PM
In defense of the low tails machines, I must say that I had no problems with yaw in my Air Command. I have (had) a 65 HP Rotax engine and the gyro stayed right on the centerline during takeoff and landings. Maybe all the balancing on the mains that I did (4 hrs) have paid off, but I can't remember ever having to deal with yaw.

Roll due to prop torque is another story.

Udi

Rotornut
09-18-2004, 07:22 AM
Mike nice write up. A nice Neon Yellow and Black Dominator I see in your Future. lol
Catfish has wanted one for Years. But shhhh 2 Years to complete the one he has.
Lots of long nights and weekends for us All!

Great articile you should send it to the PRA Editor. Some do not read the forum.
MJ :)

ben
09-18-2004, 08:02 AM
hi again, im making this tail out of chromemolly and fabric 60inches tall 60 inches wide and 18" deep. is there a real need for it to be shaped like airfoil. reason i ask is i was looking a aronka champ and it's tail feathers were pretty flat ?

GyroRon
09-18-2004, 04:56 PM
I would make the tail fixed with a moveable rudder aft of the fixed portion just like on the Champ. Flat shape I think will be plenty fine. Doing the tail with two pieces like this and you don't need a anti servo tab and straight line stabilty will likely be better. If you put on a stab in the prop wash like on a Dominator tail, put it on the fixed portion of the tail and make it big, As wide as the prop is from tip to tip would probably do it.