Dominator vs. Vortex

[Master Roda]

Originally Posted by C. Beaty

Whether or not a rotor can be hand started is largely irrelevant if one has a prerotator. The only two gyroplanes to receive type certification after WWII were the A&S 18A and the McCulloch J-2; both having symmetrical, impossible to hand start rotorblades. But that didn’t interfere with the certification process.

I'll skip everyting else in your post and just say that the 18A and J-2 were jump take off machines because my wife is calling and I dont' want to disappoint her. Have a good day Chuck.

[Redbaron]

[QUOTE=C. Beaty;488994]
The problem with gyros is that nearly anything can be flown due to control by rotor thrust vector orientation. Just sort of follow the Bensen layout.
QUOTE]

The best test of stability is to lock the cyclic up and fly into rowdy air as you have suggested before. good post cb!

[Jason O]

Originally Posted by Master Roda

Explain to me Mr.Omelchuck what a double hang test has to do with stance. As far as I know stance is the wheelbase and height of a said vehicle, not how it hangs in relation to CG.

Every design of a flying machine is a compromse. The designer decides what is important to them and what is less important to them and goes from there.

It is my understanding that it was very important to Ernie that his design had a thrust line that was in line with or lower than the vertical CG. To keep a large propeller and meet this requirement, the occupant must be moved higher to meet the CG requirement. All the desingns that have this as their first requirement tend to be taller and have a longer landing gear. Since the designer picked the thrustline/CG as the first requirement they may have to compromise other things such as roll over angle and strength of the gear.

If the thrust line through the CG is not the top requirement of the designer they can have the benefit of other design features but will not get the possible benefit of the thrustline being through or lower than the CG.

In my opinion this CG/thrustline requirement some designers want to incorporate in their machines drives the look (stance) of the machine.

Jason

[MrGrey]

Originally Posted by Master Roda

I'm sorry,you may be right on the heavy part, but where do you get your drag numbers? The last Vortex I measured empty with a modified 618 weighed about 390 lbs (less rotors). What does a Dominator weigh?

My 618 Dominator is between 30-40lbs lighter empty. My two place 618 was 400lbs even. Both weights are WITH rotors. Any addtional weight on a gyroplane is additional drag and as a result will adversely affect performance characteristics....but may add to overall safety and/or comfort. Like many things there is a trade off

I've never seen a gyro pylon race, where was this one held? Is there a video of it? I think the pilot would also be a factor. An example being an auto race between 2 drivers with identical cars.

I remember seeing one, I took second place to a helicopter at that contest at Mentone in front of a large crowd.

Where was this contest held? Is there a video of it? I agree that power to weight is important, but so is rotor performance. Last I checked, Sport Rotors can prerotate by hand and lift off earlier than most rotors due to the specific airfoil. I would say that this enables a shorter take-off as shown in our videos (please check sportcopter.com or our youtube channel). I've never done a side by side comparison though, so I could be wrong.

Ask and you shall receive.. Standings 1. Yamaha Tandem Dominator, 2. 582 Dominator, 3. 912 Dominator, 4. Sportcopter

Gyrocopter / Gyroplane Time to Climb Contest PRA Convention Mentone 2009 - YouTube

True Mr. Grey, as indicated by your avitar.

As an associate of Sport Copter, I am totally biased. That said, I believe that training is more important than the machine.

This thread wasn't about performance anyway. The thread originator was asking about the design stance.

Mr Grey, why do you suppose the Dominator is so high in it's stance? Or perhaps the designer or employee of the Dominator can help us here? I can only guess it has something to do with thrustline or clearance issues.

Gyro guru Chuck Beaty has answered this better than I can

Both are xcellent machines with great safety records and I will submit to overall build quality to Sportcopter and overall comfort in a stock configuration.

[NoWingsAttached]

I have never owned a Dominator or a Sport Copter, so my opinion is 100% neutral.

I have considered both machines, and settled on a third design. That said, here goes.

I really admire and respect both Ernie (Dominator) and Jon (Sport Copter). I have never met Jon. I have, however spoken with Ernie COUNTLESS times at Mentone, Bensen Days, and even WRENS. In my opinion, Ernie is THE most accessible builder out there, and the THE best provider of gyro parts and information. Got to love Ernie and what he provides the gyro community.

Now the hard part.

Suspension: The main axles are hollow, and I know of an instance where it sheared on the tarmac and caused a rollover. Replace the kit axles with solid axles if you decide on a Dom.

It's rumored that the RFD braking system has a tendancy to grab, but I'm told you get used to it. When I look at it, I see wheel barrow wheels - and drum brakes. It just doesn't look good.

The narrow wheel base, and 100% independant, active, suspension is a combination which can lead to a duck walk instead of dampening it. Good way to roll over a gyro in a bad landing. Think race cars with sway (anti-roll) bars. When you go into a turn, and load the outside wheel, the LAST thing you need is for the inside wheel to be adding to the roll. Same physics for gyros. There are obvious benefits to having BOTH wheels compress at similar ratios relative to the ground on impact. If you land with more weight on one wheel than the other, an independantly-sprung opposite side wheel INCREASES the roll force during an unbalanced landing incident of the machine, when it should be decreasing the tendancy to roll. One shock absorber, sprung, should be used for BOTH wheels, tied together. When one side compresses during landing, the other side should compress at a similar rate. (It would also decrease unecessary weight and expense.)

Frame: You CAN impact the ground unexpectedly at 45 MPH flying gyros, regardless of how good you are as a gyro pilot. Look at the YouTube of that guy in GB who designed, built and rolls "Nellie", then tell me it can't possibly happen to you, too. You think he was a novice pilot? Nope. Probably has more gyro seat time than anyone here except Birdie. I wouldn't want to do it in a machine that has nothing between my nuts and the ground, except a 2x2 square tube (Dom), that I am sitting DIRECTLY upon - so that if the frame hits the ground, my ass if grass, literally and figuratively. The case may be extremely rare, but it can, and does, happen. Multi-tube frames are superior to a single-tube keel design in an impact event.

Rotors: Never flown Sports'. I do, however, KNOW that they are the most expensive gyro hardware on the market.

But you get what you pay for. I have a set of composite blades (Sky Wheels) and can attest to the fact that they are stiff (a GOOD thing) and fly VERY nicely in all aspects of flight.

RFD blades are REALLY AFFORDABLE!!!! I have several sets of them, and will continue to purchase them til the cows come home. They seem to fly about 5 mph faster than anything else. The down side: You'd better have your landing set up well, because they are not forgiving when it comes to the ragged edge of supporting the weight of the gyro in the air and quitting on you. Every other blade I have flown lands better than a Dragon Wing, but Dragon Wings seem to fly faster, and therefore must have less drag overall in flight trim.

But, believe me, the RRPM decays significantly faster than other blades. If you are ready and are mindful of that, then you should be OK in all situations.

Dominator is far ahead of the game in simplicity. If you want something easy to build, look no further. Also, the hydraulic prerotator Ernie offers is really nice. I do love it, on several levels. Make sure you spend the $$ and get that.

The controls of the RFD are leveraged differently than the other gyros, and it apparently adds to a light stick feeling. This is good. Maybe. Can't say for sure, never owned it. But the owners respond that they love it, so I am passing that along. I am not a body builder, and have never noticed that it is hard to move my stick in my "other" machines. Not sure why this is important. But the Dom pilots seem to like it.

Wish I knew more about Sport Copters, but, well, there are just MORE Doms in the air than Sports, so I have more feedback and understanding of the Doms and their quirks than the Sport Cs, though I've never known a Dominator owner who didn't love his gyro.

Or a Sport C guy who didnt' love his.

Seems to be an epidemic. We all seem to have nothing but wonderful things to say about OUR machines! That's why it may be a good thing to read what a neutral party has to spew on about these things. Or not. I am just another gyro builder, trying to find answers and solutions, just like everyone else here.

In the wise words of my esteemed CFI: "That's why they're called 'Experimental' Aircraft".

Good luck!

Lots of love to both Ernie and Jon! Hope you love me too. YOU guys are the BEST!!!

(Can i have that Budweiser in your cooler?)

[Master Roda]

Thank you Mr Grey.
I noticed that the guys flying the Dominators had a different take-off technique. It looked like they used up the runway getting a higher speed, then using the rotor energy to get a fast climb. The guy in the Vortex lifted off sooner and his climb looked slower.
I would like to see a pylon race someday. Is there an event that holds them anymore?
We got off track here again. This thread was supposed to be about design philosophy, not whos machine is better. I think the Dominator is a great machine with many happy customers. You just can't go wrong with that now can you?

[Master Roda]

Originally Posted by Jason O

In my opinion this CG/thrustline requirement some designers want to incorporate in their machines drives the look (stance) of the machine.

Jason

That's well and fine Jason, but you didnt explain what a hang test has to do with stance. I think I know what you're trying to say though, so no need to reply.

[Master Roda]

Originally Posted by NoWingsAttached

Lots of love to both Ernie and Jon! Hope you love me too. YOU guys are the BEST!!!

(Can i have that Budweiser in your cooler?)

Yes Greg, love you too. Maybe someday we'll have some beers together
I consider most of the gyro community as friends anyway. We will all get over our ego's when we meet in person.

[Heron]

Bang for the buck! (#1 option)
Flight envelope (#2) (what do you want?)
Simplicity (#3) (easier replacements)
Sophistication (#4) (very few people looking for this)
Other than that, both machines are pretty close in envelope, they will just fly it differently!
Rotors and engine will determine differences, tail will be a second item.
Heron

[Master Roda]

Originally Posted by C. Beaty

The Dominator has a low thrust line; the propeller thrust line being lower than the CG. That’s what determines the “stance.”

That's what I had assumed, but it wasn't my place to say so.

Originally Posted by C. Beaty

I prefer CLT as exemplified by the Aviomania “Genesis.” Designer Nikolas Karaolides is one of the very few qualified engineers associated with gyros.

I like that gyro as well, but I prefer tractors like the LittleWing. If I had more pennies I would have one with a radial engine

Originally Posted by C. Beaty

A rotor and a bushplane wing are two different things. The wing of a bushplane can’t go any faster than the rest of the airplane.

Ok, bad analogy on my part.

Originally Posted by C. Beaty

The Dreadnought class gyros need blade chord of 16” or so if seesaw rotors.

But since that is really hard to achieve, we have to live with 9" and spin them too fast

Originally Posted by C. Beaty

Whether or not a rotor can be hand started is largely irrelevant if one has a prerotator. The only two gyroplanes to receive type certification after WWII were the A&S 18A and the McCulloch J-2; both having symmetrical, impossible to hand start rotorblades. But that didn’t interfere with the certification process.

I've flown the J-2. I can't figure out for the life of me how it got certified other than someone had the money to get it done. I don't like the way it flys. Speaking of dreadnaught class.....and the J-2 has what? 6 or 7" rotors? Way off from the 16" you mention. I know you were reffering to see-saw rotors, but then again were talking about a three bladed articulating system and it is vastly different altogether

[Vance]

I have stayed out of this thread because I have not flown a Sport Copter so I can’t compare it to a Dominator that I have flown several of.

I have Sport Copter blades on the Predator; I like them a lot.

I know nothing about the design philosophy of either aircraft even though I have spent a lot of time with Ernie and have visited both factories and spent time with Jon and received council from Jim.

I have some divergent opinions to Greg’s and I will share them here.

I have watched many hard landings in Dominators. If you want to replace the axels fine, I wouldn’t because in my opinion Ernie has done a good job of making things work together.

The Dominators I have flown steered fine and I think that the wheels and brakes are inexpensive and light. It is hard to imagine having a problem with either with normal usage.

I don’t know what is meant by a narrow wheelbase. Perhaps Greg meant a narrow track. I feel for the weight and CG of a Dominator; the track is adequate.

I took my flight review in a Dominator and landed badly in a gusting crosswind and I could not find a tendency to “duck walk.” The suspension seemed compliant and well dampened to me.

Greg posted: “Frame: You CAN impact the ground unexpectedly at 45 MPH flying gyros, regardless of how good you are as a gyro pilot. Look at the YouTube of that guy in GB who designed, built and rolls "Nellie", then tell me it can't possibly happen to you, too. You think he was a novice pilot? Nope. Probably has more gyro seat time than anyone here except Birdie. I wouldn't want to do it in a machine that has nothing between my nuts and the ground, except a 2x2 square tube (Dom), that I am sitting DIRECTLY upon - so that if the frame hits the ground, my ass if grass, literally and figuratively. The case may be extremely rare, but it can, and does, happen. Multi-tube frames are superior to a single-tube keel design in an impact event.”

I have not seen evidence that suggests a multi tube frame is safer in a gyroplane accident and I study every gyroplane accident I can find information on.


Greg wrote: “Rotors: Never flown Sports'. I do, however, KNOW that they are the most expensive gyro hardware on the market.”
“But you get what you pay for. I have a set of composite blades (Sky Wheels) and can attest to the fact that they are stiff (a GOOD thing) and fly VERY nicely in all aspects of flight.”

“RFD blades are REALLY AFFORDABLE!!!! I have several sets of them, and will continue to purchase them til the cows come home. They seem to fly about 5 mph faster than anything else. The down side: You'd better have your landing set up well, because they are not forgiving when it comes to the ragged edge of supporting the weight of the gyro in the air and quitting on you. Every other blade I have flown lands better than a Dragon Wing, but Dragon Wings seem to fly faster, and therefore must have less drag overall in flight trim.”

“But, believe me, the RRPM decays significantly faster than other blades. If you are ready and are mindful of that, then you should be OK in all situations.”

Sport Copter Blades are not the most expensive gyroplane rotor blades on the market. I have received good value for my money with my Sport Copter blades.

I have flown Sky Wheels and experienced an uncomanded pitch up. I would prefer Dragon Wings or the Sport Copter blades to Sky wheels. I don’t know what this had to do with the comparison.

In my opinion the rotor rpm does not decay any faster with the Dragon Wings compared to the Sport Copter blades. When I took my flight review; the two place Dominator with two large people on board weighed more than the Predator solo and in my opinion there was little difference in how fast the rotor RPM decayed.

If I was concerned with fast rotor RPM decay I would get Dragon Wings with the heavier tip weights.

For me the Dominator was an easy aircraft to fly.

I have passed up two opportunities to fly a Sport Copter because in my opinion it was not a good time for me. I hope to get some experience in a Sport Copter.

I have seen a lot of them fly and they appear to fly well.

I do not know the reason for our divergent opinions.

Thank you, Vance

[MrGrey]

Originally Posted by Master Roda

Thank you Mr Grey.
I noticed that the guys flying the Dominators had a different take-off technique. It looked like they used up the runway getting a higher speed, then using the rotor energy to get a fast climb. The guy in the Vortex lifted off sooner and his climb looked slower.
I would like to see a pylon race someday. Is there an event that holds them anymore?
We got off track here again. This thread was supposed to be about design philosophy, not whos machine is better. I think the Dominator is a great machine with many happy customers. You just can't go wrong with that now can you?

Not saying one is better than the other... it is the Chevy vs. Ford discussion. However, the design philosophies lead to differing flight characteristics as pointed out. I see the difference as performance based vs. comfort in the design philosophies, although they both perform very well. IMHO if you wish performance (corvette) purchase a Dominator, if you wish comfort (cadillac) purchase a Sportcopter... either way they are great vehicles that are tailored for specific clients.

I have flown them both and prefer very fast low level barnstorming and the Dominator suited me best for my type of aggressive flying. The Sportcopter was very nice to fly and the rotors were smooth as silk, but it lacked the yanking and banking crispness I enjoy with 22' DWs and a 618 with a 72" prop that I now fly. The additional overall weight and heavier rotors prob made the difference in noticeable characteristics for me.

That said, very few people enjoy the type of flying I do because they do not like 100mph wind in your face at very low altitudes and rapid reaction type aggressive maneuvering.

[Master Roda]

Originally Posted by MrGrey

Not saying one is better than the other... it is the Chevy vs. Ford discussion.

Agreed.

Originally Posted by MrGrey

That said, very few people enjoy the type of flying I do because they do not like 100mph wind in your face at very low altitudes and rapid reaction type aggressive maneuvering.

I'm also one of those people (I like fast,hard banking) Jim has promised to let me fly the factory M912. Good for me as I cannot possibly afford one. I used to fly a Lightning and although it wasnt fast, I liked the way it responded to cyclic inputs (23' rotors). I usually fly our tandem (testing rotors), and the thing handles like a truck in comparison.
Have a good day Mr. Grey

[rfsolutions]

1. Ruggedness of suspension.
Newest version of vortex 912 lands and takes off on runway full of 2x4s while maintaining a relatively smooth (low shock) ride for pilot & machine.
Never saw a dominator do that?
2. Flight capability.
Loops and rolls can be done in a vortex over & over.
Never seen it done in a Dominator?

The greatest performance numbers (climb) are typically produced by the best weight to thrust ratio machines. Just because a Dominator 582 out climbed a Vortex 582, doesn't mean another pilot flying a different 582 with another prop or pitch on a different vortex wouldn't have a different outcome. Individual machine and pilot variables have too much of an affect on the outcome of a time to climb event to match one design against another.

The two machines are different design philosophy's. Both have a good safety record and are pretty fun and stable to fly. Both perform pretty well. One is more expensive than the other. I would have no reservations flying either design. Pretty much a Chevy & Ford argument.

[BEN S]

One thing no one mentioned in specifics as it relates to design features and built in comfort....getting in and out of the seat!
I have seen a couple of Doms that were so high up they needed a step to get up in them. No problem if your somewhat athletic, but the Sportcopters seat sits lower "by design" than the the others.
Never seen a person hand start a Dom, but after doing it for years in the Sportcopter, it is a VERY athletically coordinated ballet. Not un doable, but nowhere near as easy as my buddy's Bensen.