Ruggedized Gyro?

Im assuming your no reply to my last post isa hint im close CB?
 
OK, let's slow down. When the TV weather babe says the wind is blowing 14 mph out of the NE, she would be technically correct to say; “The northerly component of wind is 10 mph as is the easterly component.”

It is the same with a rotor blade, inflow and and rotational velocity combine is such a way that as far as the rotor blade is concerned, there is only one single, solitary wind.

In a helicopter, inflow is downward and the resultant of inflow and rotational velocity is also downward. This decreases the angle of attack of a rotorblade, requiring more collective.

In a gyro, inflow is upward and the resultant of inflow and rotational velocity is also upward. This increases the angle of attack of a rotor blade, requiring less pitch.

But the angle of attack doesn't remain constant along a rotor blade. At the tips, the rotational velocity is much higner so inflow doesn't change the angle of telative wind very much. At the inboard sections, the effect of inflow is much greater, producing a very high angle of attack in a gyro and a very low angle of attack in a helicopter. Thus, gyros and windmill blades are twisted tips up and helicopter and propeller blades are twisted tips down.

So, stall in gyro blades begins at inboard stations; helicopter blades stall at the tips.

A couple of simple vectors explain resultant velocity over a blade better than any long winded discussion but not everyone gets along with vectors.
 
To Birdy
Watch this sketch

 
Thanx for your persistance boss.
My thickness, im gessn, dosent just piss me off.
You make it so symple, coz it is.

Best i just stick to grown cows. :(
 
Birdy- Keep growing them cows. They help feed great minds such as yours, Chucks, and Jean Claudes....unless Chuck and Jean don't eat Australian beef!
 
So tell me chuck if that's the case why did you think it was a good idea to use heli blades on a gyro?
 
So tell me chuck if that's the case why did you think it was a good idea to use heli blades on a gyro?
Hughes rotor blades are symmetrical with a NACA 0015 airfoil.

Turn them upside down, spin them backwards and you have gyro twist.
 
The ideal répartion torsion showed by the theory is undoubtedly in the opposite to that of a propeller or helicopter rotor .
However, between ideal twist and flat blade, the practical benefit seems to me negligible for an autogyro. The proof is the performance peaks of an propulsion propeller to variable pitch is not significantly decreased when the pitch is changed, despite the mismatch A.o.A along the blades (from NACA report 640)
 
Twist in a gyro blade, JC, permits slightly higher incidence setting with slightly lower RPM. This improves L/D ratio and it doesn't cost much.

I measured L/D of several rotors many years ago by measuring rotor disc angle as the gyro flew past in level flight at 60 mph. I don't have my original notes but the results, from memory were:

DW--------------8.5:1
SkyWheels-----7.5:1

DWs use a cambered and reflexed NACA 4 digit airfoil and SkyWheels an excellent implemantation of NACA 8H12. Skywheels are straight and DW are twisted and run at a lower RPM.
 
Twist in a gyro blade, JC, permits slightly higher incidence setting with slightly lower RPM.

L/D DW------------8.5:1
L/D SkyWheels-----7.5:1
Skywheels are straight and DW are twisted and run at a lower RPM.
I agree, Chuck, lower RPM produced by an increased pitch setting improves the L/D ratio. As true with flat blades. No need to twist for that.
One must compare with the same RPM, therefore the same losses.
In my opinion, DW is just closer to mu limit for which the autorotation disappears. The safety margin is reduced, just as well with flat more pitched blades .
 
JC, when I first started flying gyros ~1967 and knowing nearly nothing of the theory, I made copies of Bensen metal blades; ~8H12 with flat bottom surface and segmented upper skins that worked best as a centrifugal air pump via leakage through the gaps between skin segments.

In one experiment, I set the incidence as high as the adjustment permitted. No prerotator but by double teaming hand spinup, managed to get them started. Very interesting result.

Top speed was ~20 MPH with the cyclic stick jammed forward against the stops on the rotorhead. More throttle = climb; less throttle = descent, all at ~20 mph.

Others did the same with Rotordyne blades; also flat bottom and with blunt leading edge. The impression was screwing up and down in proportion to power setting.

I would say that when the stick reaches the forward stop, one has discovered the mu limit. The stalled portion of the retreating blade causes cyclic flapping so great that that the rotor disc angle behaves like the friction speed governor of an antique wind up phonograph.
 
Chuck, What I understand from your text is "there is no danger to reach the limit mu, because a1 prevents an excessive forward speed"
I try to understand how RRPM is maintained, despite the expanded stall.

Now, assuming RRPM not decreases, the fact remains that DW is closer to this excess of a1, and it's like a higher pitch setting of flat blades, no?
 
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JC, any rotor with zero pitching moment coefficient will cause the stick to move forward as airspeed increases and I believe most will reach the forward stop before anything bad happens.

This movement is increased if the blades have a positive pitching moment coefficient, the advancing blade twists nose up, increasing cyclic flapping. Bensen wood blades had a coefficient of ~+0.04 and the stick would reach the forward stop at 50-60 mph.

Blades with a negative pitching coefficient twist nose down on the advancing side, suppressing cyclic flapping and if severe enough, the stick moves rearward with increasing airspeed. That’s a dangerous situation, likely making a high speed dive unrecoverable.

All rotor blades will twist in response aerodynamic forces if the pitching moment coefficient is not zero; some more than others depending on torsional stiffness.
 
Thank you for your explanation, Chuck. My calculation shows that the RPM decreases before the a1 exceed 5 °, but now I guess this can be reversed because the twist "nose down" of the stalled sections.
 
Hughes rotor blades are symmetrical with a NACA 0015 airfoil.

Turn them upside down, spin them backwards and you have gyro twist.

Ah the good old flip and reverse trick
 
Good Day Gents. The question about the big wheels can be explained, and yes we have more than 4000 hrs on this configuration. The wheel track is wider, the powerplant slightly higher and the undercarriage closer to the propeller. (Plastic fenders and wheel spats wastes time when you want to do a quick wheel change) In this configuration if stones are picked up, they are thrown clear underneath the prop. The Trojan has flown anti-poaching missions in the Kruger National Park with the South African Special Forces. Wagtail developed a trailer where the gyro can be loaded or off-loaded in 15 minutes. The advantage for the operations from rough terrain, is that the poachers has people with mobile phones at the various airstrips looking at the different operations, i.e. Airforce, Police or commercial. They then contact each other and discuss the direction the aircraft took of in as well as the load, soldiers, rangers or tourist. We had permission to launch anywhere. We could launch from a piece of grass flatland and have radio contact and would then recover the gyro and pilot at another venue. This kept the poachers guessing. In the time that we where there, there was no poaching in the areas that we patrolled.
Ps. The Kruger National Park is nearly the same size as the State of Israel and there are approx. 12 poaching parties in the Kruger at any point in time.
 
The Ruggedized Gyro's (Trojan, LDG and Trooper) were developed after a requirement from the South African Army Special Forces. Wagtail was given a User Requirement Statement (URS) with quite a few requirements. A project team was assembled from the South African Airforce and seconded to SForces. Various microlight and recreational gyrocopter suppliers were visited. The URS specified quick turn around, logistics, availability and cost, amongst others. There was nothing available at the time to fulfill the requirements. A few Trike microlights were acquired as a stopgap whilst the Gyroplane was developed. The basic specs were 120 kg per seat and 135 Lt worth of mogas fuel. The fuel spec went as low as 87 octane. This in the event that you were out in the bush and could only source low grade or "cut" mogas. The propeller is easily replaceable, the rotor can be removed in the bush, the engine can easily be repaired or replaced. We played around with Composite vs Aluminum blades and standardized on Aluminum blades. We also have a hydraulic pre-rotator. This allows high pre-rotating speeds and is easy to maintain with a very, very low failure rate. Because a Subaru powerplant is used, spare parts are also readily available internationally. The ruggedized gyro is alive and well and being improved continuously.
 
The Ruggedized Gyro's (Trojan, LDG and Trooper) were developed after a requirement from the South African Army Special Forces. Wagtail was given a User Requirement Statement (URS) with quite a few requirements. A project team was assembled from the South African Airforce and seconded to SForces. Various microlight and recreational gyrocopter suppliers were visited. The URS specified quick turn around, logistics, availability and cost, amongst others. There was nothing available at the time to fulfill the requirements. A few Trike microlights were acquired as a stopgap whilst the Gyroplane was developed. The basic specs were 120 kg per seat and 135 Lt worth of mogas fuel. The fuel spec went as low as 87 octane. This in the event that you were out in the bush and could only source low grade or "cut" mogas. The propeller is easily replaceable, the rotor can be removed in the bush, the engine can easily be repaired or replaced. We played around with Composite vs Aluminum blades and standardized on Aluminum blades. We also have a hydraulic pre-rotator. This allows high pre-rotating speeds and is easy to maintain with a very, very low failure rate. Because a Subaru powerplant is used, spare parts are also readily available internationally. The ruggedized gyro is alive and well and being improved continuously.
Do you have any video or photos of this particular aircraft flying with 3 passengers or equivalent cargo. Do not see any on the Wagtail website. Also interested to know what takeoff distances when fully loaded.
 
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Loftus, thanks for the question. The project was stopped before the first flight. It was a military project and fell under their command / rules. The user requirement was a 1 metric ton MAUW, with a 100m / 320 ft distance to lift off. She is fitted with a 36ft aluminum rotor and the Subaru 3,3 litre Turbo powerplant. The Trooper is now in the process of being prepared for the Civilian Commercial environment. We are busy with the SA Civil Aviation Authority to apply for the Proving Flight Authority. The Trooper is currently not high on the priority list, hence going slow. We are in discussions with our local National Sea Rescue Institute (NSRI) (See what they do on https://www.nsri.org.za/) The intention being to have the Troopers available over the holiday seasons to assist with lifeguarding operations around the coast. Basically having lifeguards on board that can jump and support the person in trouble.
We are however busy with the Tourist which is based on the Trooper but with the pax in an open cockpit (Like the Trojan) but sitting at the rear in a side-by-side configuration. We had some enquiries from honeymoon couples that wanted to go on a tour around the country, hence this configuration.
For all the Wagtail Gyros we basically use the same keel, undercarriage, propeller, rotor design, controls, seats, instruments, etc. There is enough place for adjustment in / on the rotor-head, engine thrust angle, rudder assembly, etc to tailor the basic product to fit any required fuselage. This from the LDG, Trojan, Trooper and Tourist. The concept was brought from the military where the plan was for the mixed fleet to be maintained and kept operational with a minimum batch of spares that had to be interchangeable.
I trust this answers your question.
 
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