Concept for New (maybe) VTOL Craft
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Mart,
Your confused? So am I.
It's all Nick's fault. He threw down the gauntlet many years ago when he said that there's no such thing as a free lunch.
With a little more seriousness; every concept (configuration) has its pros and cons. Some improvements may be worthy of a free coffee-brake, but none are worthy of Nick's free lunch.
Sikorsky held off further development of the ABC concept for 30 years. Waiting for outside entities to develop new materials and devices cannot be the only reason. The X2-ABC will have incremental improvements over the XH-59A ABC . In addition, I sincerely think that the Intermeshing and Interleaving configurations will be better than the Coaxial.
However, in any future battle for the high-speed VTOL market both the ABC-Rotorcraft and the Tilt-Rotor will have their pros and cons.
IMHO, the primary limitation with the ABC craft is its speed limitation. Prouty has said "What is good for high speed flight is bad for hover and what is good for hover is bad for high speed flight." The same might be said about reverse velocity and forward velocity. At this point in time, it appears to me that anything that is done to the blade to minimize or utilize the effect of reverse airflow will create a greater impediment to conventional airflow.
Perhaps this section on Reverse Velocity Utilization will help inspire someone to come up with a solution, get a patent, and make a zillion dollars.
Just my two cents.
Dave.
PS. The UniCopter ain't dead. Far from it. It's just that one should have 'a number of irons in the fire'.
Dave, what I'm confused by is that you were championing separate lift and thrust rotors. Why the change of view to what to me appears less ideal?
It's all Nick's fault. He threw down the gauntlet many years ago when he said that there's no such thing as a free lunch.
With a little more seriousness; every concept (configuration) has its pros and cons. Some improvements may be worthy of a free coffee-brake, but none are worthy of Nick's free lunch.
Sikorsky held off further development of the ABC concept for 30 years. Waiting for outside entities to develop new materials and devices cannot be the only reason. The X2-ABC will have incremental improvements over the XH-59A ABC . In addition, I sincerely think that the Intermeshing and Interleaving configurations will be better than the Coaxial.
However, in any future battle for the high-speed VTOL market both the ABC-Rotorcraft and the Tilt-Rotor will have their pros and cons.
IMHO, the primary limitation with the ABC craft is its speed limitation. Prouty has said "What is good for high speed flight is bad for hover and what is good for hover is bad for high speed flight." The same might be said about reverse velocity and forward velocity. At this point in time, it appears to me that anything that is done to the blade to minimize or utilize the effect of reverse airflow will create a greater impediment to conventional airflow.
Perhaps this section on Reverse Velocity Utilization will help inspire someone to come up with a solution, get a patent, and make a zillion dollars.
Just my two cents.
Dave.
PS. The UniCopter ain't dead. Far from it. It's just that one should have 'a number of irons in the fire'.
Last edited by Dave_Jackson; 13th Aug 2008 at 15:06. Reason: Added PS
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New Future VTOL
Just came up with an old but really simple design.
Great idea.
YouTube - Custer Channelwing in Flight
Welcome to the Custer Channelwing Website.
That Extra Little Lift | History of Flight | Air & Space Magazine
should be enforced by nasa and some companies.
Great future and probably the highest amount of power to lift ratio.
Great idea.
YouTube - Custer Channelwing in Flight
Welcome to the Custer Channelwing Website.
That Extra Little Lift | History of Flight | Air & Space Magazine
should be enforced by nasa and some companies.
Great future and probably the highest amount of power to lift ratio.
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Interesting concept, but would suffer from mildly poor autorotational characteristics... 
The same is true of any design using engine power to drive airflow over the wing. If electric motors and batteries were used as backup power until normal gliding could be established - but this eats significantly into payload. Best for any design to just be capable of powerless descent.
The same is true of any design using engine power to drive airflow over the wing. If electric motors and batteries were used as backup power until normal gliding could be established - but this eats significantly into payload. Best for any design to just be capable of powerless descent.
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Possible future VTOL craft
This non-technical paper may be of interest; Recent Development of Rotorcraft Configuration
Mart,
The above paper relates to our previous discussion on this thread.
Going a little deeper into the subject, this page has information on Sikorsky's Variable Diameter Tilt Rotor.
In the past, link #2 provided the article for free. Currently, there are numerous links to it on Goggle, but all, or most, want money.
Dave
Mart,
The above paper relates to our previous discussion on this thread.
Going a little deeper into the subject, this page has information on Sikorsky's Variable Diameter Tilt Rotor.
In the past, link #2 provided the article for free. Currently, there are numerous links to it on Goggle, but all, or most, want money.
Dave
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Interesting paper about the variable diameter tilt rotor. Sounds more complex than the V-22 if that is possible.
I saw the V-22 fly at Oshkosh earlier this month.
And the Martin jetpack was demonstrated for its first public display. The jetpack was really two ducted fans with a piston engine for power. It managed to climb about 4 feet. The designer said flights of 6 feet have been accomplished. It seemed to require two assistants for stability.
slowrotor
I saw the V-22 fly at Oshkosh earlier this month.
And the Martin jetpack was demonstrated for its first public display. The jetpack was really two ducted fans with a piston engine for power. It managed to climb about 4 feet. The designer said flights of 6 feet have been accomplished. It seemed to require two assistants for stability.
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Dave, some interesting papers there - a lot to go through...
I'm still not convinced the complexity of variable diam is justified when variable rpm is also considered. Those centrifugal forces are not to be easilly dismissed. Even then most of these configs still struggle to achieve a low disk loading. And the mass of all those complicated mechanisms nibbles into payload. And as for modes of failsafe...
I'm still rootin' for X2, since to me it is the best way to get a helicopter to perform at speed.
I'm still not convinced the complexity of variable diam is justified when variable rpm is also considered. Those centrifugal forces are not to be easilly dismissed. Even then most of these configs still struggle to achieve a low disk loading. And the mass of all those complicated mechanisms nibbles into payload. And as for modes of failsafe...
I'm still rootin' for X2, since to me it is the best way to get a helicopter to perform at speed.
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'Joint Heavy Lift' program
Graviman & Slowrotor
Mart, there might be reasons to worry about the X2's future.
Initially, five proposed configurations were funded for 'Joint Heavy Lift' program evaluation. It then got reduced to following three.
There is an article in the new issue of AHS's Vertiflite on the JHL program. This article says that the door has been opened for Sikorsky's Variable Diameter Tilt Rotor to now be included in the ongoing configuration evaluations.
Dave
Mart, there might be reasons to worry about the X2's future.
Initially, five proposed configurations were funded for 'Joint Heavy Lift' program evaluation. It then got reduced to following three.
- Heavy quad-tilt-rotor from Bell-Boeing
- Optimum Speed Tilt-Rotor technology pursued by Karem and Lockheed Martin
- JHL - Sikorsky's X2 technology
There is an article in the new issue of AHS's Vertiflite on the JHL program. This article says that the door has been opened for Sikorsky's Variable Diameter Tilt Rotor to now be included in the ongoing configuration evaluations.
Dave
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The (Self rotating wing)
I have been on this site before and I'm wondering why the Industry has Lost interest in it? It is a (Super) efficiante Lifter and My prototype works well powerd by Electric Motors with props.see it at twitter charles Glazebrook or r/cuniverse?
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Dave,
Have You ever consider idea of Variable Solidity Rotor, ... instead of Variable Diameter Rotor ?
Have You ever consider idea of Variable Solidity Rotor, ... instead of Variable Diameter Rotor ?
No meaningful consideration about variable solidity.
My closest consideration has been that of high solidity and variable tip speed, such as; DESIGN: UniCopter ~ Rotor - Disk - Large Chord & Low Tip Speed.
We are both posting on the new thread 'A New Rotorcraft Called a Tiltplane' on another rotarywing forum. I will post a response to Variable Solidity there.
Dave
