Most roomy Gyro or 4 seater ?

RotoPlane

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Hi Ed,

What model of 4 seat gyroplane is that? The rotor head resembles an early Hughes 500 rotor head & blades. The blades definitely look like helicopter blades with the nominal 8 degree "washout" at the tips, compared to the McCulloch J2 rotor blades with the "washin" tips.

Wayne
Wish I knew Wayne.....I think it is an outstandingly good looking machine.
I understood that it is a Russian design.
 

RotoPlane

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.......The Jet Ranger incidentally, has the same basic rotor system that most of us use.
The Bell Jet Ranger uses a semi-rigid rotorhead and the hub cannot tilt in relation to the rotorshaft.

The Bell H-13 (47), like our gyros, uses a gimbaled rotorhead and the hub can tilt in relation to the rotorshaft.

Of course these three noted rotorcraft types use a teeter hinge to teeter the 2-bladed rotor assembly.

Both Bell helicopters use a swashplate for cyclic control, where our 'standard' gyro rotorheads have a built in "swashplate" for cyclic control.

Vance: The Predator's two rotorblades are overloaded with more lb/sq.ft. than a gyroplane should have for standard happy blades and the disk area is also smaller than the optimum.
To get the Predator's (and other heavy gyro types) optimum gyro rotor values, the two blades would need a larger chord and a larger rotor diameter.....or even better, more rotorblades......in my opinion.
That means much more rotor weight and will require more cyclic force, especially when the rotor is nearly stopped.
 
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Vance

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Vance: The Predator's two rotorblades are overloaded with more lb/sq.ft. than a gyroplane should have for standard happy blades and the disk area is also smaller than the optimum.
To get the Predator's (and other heavy gyro types) optimum gyro rotor values, the two blades would need a larger chord and a larger rotor diameter.....or even better, more rotorblades......in my opinion.
That means much more rotor weight and will require more cyclic force, especially when the rotor is nearly stopped.
Jim at Sport Copter doesn’t agree Ed.

He feels that the rotor diameter and chord are just about right for The Predator’s weight.

He makes a wider chord longer blade and would probably sell me some if he thought they would be better.

The Predator operates inside his suggested rotor RPM range so I am inclined to agree with him.
 

RotoPlane

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Gyro rotorblade manufacture's don't have much design leeway with dreadnought gyroplanes due to the gimbaled rotorhead.
If they made their rotors to agree with Cierva's ideal design spec.'s, the rotorhead and blade assemblies would need to be larger and heavier than they are now and they would be a cyclic shaking arm-full.
No problem if the rotorhead is semi-rigid or articulated.

The Cierva and Beaty ideal gyro spec.'s for a good all around performance are:
Blade Loading: 35 lb/sq.ft.
Disk Loading: 1.3 lb/sq.ft.
Blade Tip Speed: 400 ft/sec. (Note that if you double the tip speed, the profile drag power requirement increases eight times.)

A well designed single place gyro can meet those spec's.
A heavy 2 or 3 place dreadnought gyro however, needs either a 2-bladed semi-rigid rotor or a three bladed articulated rotor to provide a decent rate of climb, higher altitude, smoother flight, etc.

True....what we have now can get us in the air but a better rotorhead assembly would, in my opinion, have better performance, and be smoother and safer.
 

Vance

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Gyro rotorblade manufacture's don't have much design leeway with dreadnought gyroplanes due to the gimbaled rotorhead.
If they made their rotors to agree with Cierva's ideal design spec.'s, the rotorhead and blade assemblies would need to be larger and heavier than they are now and they would be a cyclic shaking arm-full.
No problem if the rotorhead is semi-rigid or articulated.

The Cierva and Beaty ideal gyro spec.'s for a good all around performance are:
Blade Loading: 35 lb/sq.ft.
Disk Loading: 1.3 lb/sq.ft.
Blade Tip Speed: 400 ft/sec. (Note that if you double the tip speed, the profile drag power requirement increases eight times.)

A well designed single place gyro can meet those spec's.
A heavy 2 or 3 place dreadnought gyro however, needs either a 2-bladed semi-rigid rotor or a three bladed articulated rotor to provide a decent rate of climb, higher altitude, smoother flight, etc.

True....what we have now can get us in the air but a better rotorhead assembly would, in my opinion, have better performance, and be smoother and safer.
The Predator has a two blade semi rigid teeter rotor system like most gyroplanes I have flown.

She climbs at a gross weight of 1,400 pounds at 700 feet per minute with a blade loading of 66 pounds per square inch and a disk loading of two pounds per square foot. She has flown to 12,800 feet weighing MSL at around 1,100 pounds with a blade loading of fifty two pounds per square inch and a disk loading of one point five six pounds per square foot.

If I went with the low disk loading my VNE would be reduced and I might fly solo (1,100 pounds) at 90kts with six horsepower less and at gross weight (1,400 pounds) ten horsepower less at 90kts.

Design is a compromise. In my opinion if I went with the light disk loading and low tip speed I would be less safe because the rotor rpm would be getting too low in some specific flight regimens that are common for me.

I like the feedback of an offset gimbal rotor control system and don’t care for the feel of a swashplate.

The stick shake and control forces are manageable flying The Predator with the high blade loading and high disk loading.

In my opinion disk loading and blade loading are not the reasons for the lack of four passenger gyroplanes.
 

RotoPlane

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The Predator has a two blade semi rigid teeter rotor system like most gyroplanes I have flown.......
It's obvious I'm incapable of getting you to understand what I'm trying to convey, perhaps 'cause both of us have opinions that are too entrenched.

Shoot, I cannot even get you to agree that The Predator (which I really like), does not have a semi-rigid rotorhead.....if it did, like the Helicycle, it would require a separate swashplate for cyclic control.

So I give up, you win this discussion.
 

C. Beaty

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As Tracy Crook used to say; “Fuel economy in a gyro is about as relevant as a light weight tombstone.”

Does anyone ever ask about fuel mileage in jet skis and dirt bikes?

If you have power to burn, might as well burn it with an inefficient rotor.
 
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Didn't' realize fuel efficiency was that bad, but I guess it makes sense since you are dragging that rotor along...

In comparing Gyro with HC, I'm not sure fuel efficiency is such a big factor though, when you add up the costs.... there seems to be a big price difference and difference in maintenance costs in favor of a gyro.... but then I'm not sure it's apples to apples
 
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