Supermotive
Member
I agree. I was just talking to one of my co-workers about a cad software. Fortunately my kid does not wake up before 8am. Cheers.
A new tractor design
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kolibri282
Super Member
Quote: How do you plan on mounting the rotor mast? /Quote
My idea is that a mast should be as supple as possible. If you look at light helicopter rotor masts from the Brantley to the Bell 47 over to the 206 the masts are sort of toothpicks. I think that this will reduce rotor shake. Finding the correct diameter will be a challenge though.
My idea is that a mast should be as supple as possible. If you look at light helicopter rotor masts from the Brantley to the Bell 47 over to the 206 the masts are sort of toothpicks. I think that this will reduce rotor shake. Finding the correct diameter will be a challenge though.
Supermotive
Member
I was thinking a 2” square piece of 1/8” wall 6061 t6, but the decision is not made yet.
Supermotive
Member
Here is a strange thought. What if I added some stubby wings down by my front landing gear, with big flaps that can not only control wing lift, to add a little higher speed to cross countries, but also divert prop wash up into the rotor, on the ground, to spin them up to flight rpm before takeoff?
kolibri282
Super Member
Quote: What if I added some stubby wings /Quote
The aerodynamic center of the wings (quarter chord line) would have to be very near the center of gravity of your aircraft or it would nose up in a gust. Deflecting prop wash has been tried by Cierva, I think on the C-19, but didn't come into wide use, so I think it was not a success.
The aerodynamic center of the wings (quarter chord line) would have to be very near the center of gravity of your aircraft or it would nose up in a gust. Deflecting prop wash has been tried by Cierva, I think on the C-19, but didn't come into wide use, so I think it was not a success.
WaspAir
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Yes, Cierva's so-called "scorpion tail" redirected propwash up toward the rear of the disc to get pre-rotation effect.
Alan_Cheatham
Member
Maximum speed of a gyroplane is limited by the rotor, using a wing to unload the rotor and slow it's rotational speed will reduce it's maximum not increase it. Have a look at these comments by Chuck Beaty:
Increase speed
Hello, I was wondering, what could be done, to increase the airspeed of gyros. I understand, that the rotor increases RRPM and produces more lift and therefore more drag when h-speed increases. But if the blades were shaped or hinged in a way, that they produce (a little) less lift, when...
Increase speed
Hello, I was wondering, what could be done, to increase the airspeed of gyros. I understand, that the rotor increases RRPM and produces more lift and therefore more drag when h-speed increases. But if the blades were shaped or hinged in a way, that they produce (a little) less lift, when...
Also read that NACA report I linked to in a previous post.
Supermotive
Member
As I understand, the rotor drag is enormous when nearing 100 MPH. What if stubby fixed wings could allow less angle of attack on the rotors, and have a net ground speed gain without overloading the rotor?Maximum speed of a gyroplane is limited by the rotor, using a wing to unload the rotor and slow it's rotational speed will reduce it's maximum not increase it. Have a look at these comments by Chuck Beaty:
Increase speed
Hello, I was wondering, what could be done, to increase the airspeed of gyros. I understand, that the rotor increases RRPM and produces more lift and therefore more drag when h-speed increases. But if the blades were shaped or hinged in a way, that they produce (a little) less lift, when...www.rotaryforum.com
Increase speed
Hello, I was wondering, what could be done, to increase the airspeed of gyros. I understand, that the rotor increases RRPM and produces more lift and therefore more drag when h-speed increases. But if the blades were shaped or hinged in a way, that they produce (a little) less lift, when...
Also read that NACA report I linked to in a previous post.
WaspAir
Supreme Allied Gyro CFI
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Merely adding wings to off-load the rotor won't help with retreating blade stall, but drag benefits could result in a reduction of power required at cruise speed, thus increasing endurance/range.
Supermotive
Member
The wings' 1/4 chord would be at the center of gravity. I wondered about the prop wash thing. I am not sure there is enough energy to really make a difference. I think a mechanically coupled pre-rotator is tough to beat.
Alan_Cheatham
Member
Go mechanical, you need a high degree of efficiency if you want 300 rpm.
Cierva experimented with diverting the props thrust with a biplane tail but quickly abandoned that approach.
Supermotive
Member
Alan, I think you are right about the mechanical approach. What do you think caused the crash? too much rotor momentum and bad decision with the cyclic?
Supermotive
Member
I am studying up on this now. I have a lot to learn about the auto rotation wings. There is a lot on powered rotors out there, but it seems autogiros are much different on a fundamental level.
Alan_Cheatham
Member
The issue is NO cyclic. The earlier winged autogiros used elevator for pitch control so once the aircraft landed the rotor could not be leveled to kill the lift, a real issue in strong wind. This is one reason I suggested that any taildragger gyro would best be designed with a means to fully level the rotor to facilitate rotor management during ground operations.
If you study the many patents from that time there are several inventions to help deal with rotor leveling, one was a pedal in the cockpit that when depressed would level the rotor and another was a tailwheel that was extendable thereby lifting the tail to level the entire aircraft, rotor would then follow.
WaspAir
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The old approach of elevator/aileron for control had many issues, including loss of aileron effectiveness as airspeed slowed in the landing. Crosswind operations were challenging.
In the modern era, you could have wings on a direct control rotor head machine, just not for the purpose of mounting control surfaces on them. My McCulloch J-2 had a fully articulated rotor head, with no elevator or ailerons, but still sported small wings. I never had any real numerical data to prove or disprove my perceptions, but I always suspected that at speeds above 60 or so I was getting some drag reduction benefit from a flatter-than-otherwise disc angle. Comparing the J-2 and the A&S 18A I regularly flew, which both used carbureted O-360 Lycomings with the same rated power, both had fully articulated rotors, and both had constant speed props, the J-2 was faster for a given power setting, even though the tandem wingless 18A presented much less frontal area than the side-by-side winged J-2.
[Vne on the J-2 was set well below retreating blade stall onset because the windshield was too thin/weak to take more than 105 or so without flexing inward and risking breakage.]
Jean Claude
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Did you find that the Rrpm decreased during the fast flight?
Otherwise, it means that the wing did not unload the rotor
Supermotive
Member
Thanks Wasp. I suspected the drag savings would be a result of being able to reduce disc angle. My goal is to get to about 100mph. Whether it is with the augmentation of stub wings, or other methods, I am not stuck to one idea. I am trying to get the fuselage shape such that it provides a small amount of lift around the CG. I am not sure what this will amount to, but it may help me reach my goal.
Supermotive
Member
Jean Claude, I may be saying the same thing as you but, would it be possible that the rrpm may not decrease with airspeed, but rather, just would not rise as much, at the higher speeds, when the aircraft has the stub wings; due to less increase in load (due to high speeds)?
Jean Claude
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The rotor rpm increases slightly with forward speed, for example +1.5% of rpm for +20% of forward speed.
While only 20% of the lift supported by the wing means -10% rpm if the rotor pitch setting is unchanged.
While only 20% of the lift supported by the wing means -10% rpm if the rotor pitch setting is unchanged.
Supermotive
Member
Ok. I understand Jean Claude. Thank you.
