Shameless update from Dale Kramer

Oops, that is 900 ftlbs in static conditions. It would be much less at any significant transition speed but still, I think the transition can be done without much of a zoom up. There have been all electric and 'similar aerodynamics' transition models built before and the videos I have seen of their transitions did not show much of a pull up but of course each design is different.
Bumper, yes vortex ring state conditions are possible. I believe that that risk can be reduced by adding some forward translation when you let down and by staying away from other vlift vehicles. Once near the ground of course you need to slow all movement down.
These conditions we are talking about the need for testing, just highlight why I am building a 1/4 scale model right now, not the full scale.
Didn't the Osprey put some sort of restriction on landing in close proximity to other Ospreys as an acceptable risk reduction for this issue?
Interesting to note that this condition only became apparent, years into the multi billion (I think billion) dollar program. Glad we all can take advantage of their experience.
Rotax failure results in the need for airbags if you are in transition or hover. Since all these failure we are talking about are for hover or neaar hover conditions, they would all happen close to the ground where the likelihood of a whole vehicle 'parachute' letdown or ejection seat failure would be very high. Having survived a very high rate of descent sailplane accident, where trouble began at a very altitude, I can say that, at least in my case, I believe that cockpit air bags would have greatly reduced my injuries.
For the past few years I have toyed, as many others have, with the idea of manned 'multirotor' designs. The keys to having a design with 'acceptable risk' failure modes is spending most of the flight time in aerodynamic flight, using more than 3 or 4 rotors for hover, redundant motor controllers and hover controllers (yet to be worked out) and airbags I also considered just doing transitions over water (it is softer with a landing pad of waters edge, which is funny at first but may be a good practice for risk reduction whenever possible.

Edit 'when trouble vegan at a very LOW altitude'

Edit 'when trouble began at a very LOW altitude' and 'landing pad AT waters edge'
and a few other typos, oh well!

On Thursday, March 17, 2016 at 6:17:09 AM UTC-5, DaleKramer wrote:
Oops, that is 900 ftlbs in static conditions. It would be much less at any significant transition speed but still, I think the transition can be done without much of a zoom up. There have been all electric and 'similar aerodynamics' transition models built before and the videos I have seen of their transitions did not show much of a pull up but of course each design is different.
Bumper, yes vortex ring state conditions are possible. I believe that that risk can be reduced by adding some forward translation when you let down and by staying away from other vlift vehicles. Once near the ground of course you need to slow all movement down.
These conditions we are talking about the need for testing, just highlight why I am building a 1/4 scale model right now, not the full scale.
Didn't the Osprey put some sort of restriction on landing in close proximity to other Ospreys as an acceptable risk reduction for this issue?
Interesting to note that this condition only became apparent, years into the multi billion (I think billion) dollar program. Glad we all can take advantage of their experience.
Rotax failure results in the need for airbags if you are in transition or hover. Since all these failure we are talking about are for hover or neaar hover conditions, they would all happen close to the ground where the likelihood of a whole vehicle 'parachute' letdown or ejection seat failure would be very high. Having survived a very high rate of descent sailplane accident, where trouble began at a very altitude, I can say that, at least in my case, I believe that cockpit air bags would have greatly reduced my injuries.
For the past few years I have toyed, as many others have, with the idea of manned 'multirotor' designs. The keys to having a design with 'acceptable risk' failure modes is spending most of the flight time in aerodynamic flight, using more than 3 or 4 rotors for hover, redundant motor controllers and hover controllers (yet to be worked out) and airbags I also considered just doing transitions over water (it is softer with a landing pad of waters edge, which is funny at first but may be a good practice for risk reduction whenever possible.

Borrow a foam pit from the extreme sports folks.

Vortex ring state has nothing to do with "staying away from other vlift vehicles." VRS is the interaction with your own vortex that decreases the relative angle of attack on your own airfoils/rotor blades. The recovery is to lower collective (altitude permitting) and use cyclic to pitch forward in order to fly out of the ring state - essentially to leave the vortex behind you. Simple adding power will exacerbate the "settling with power" and accelerate your descent.

I've encountered settling with power a couple of times back when I flew helicopters. The worst was when holding a stationary position at 1000' in a Bell 47 with a skysign (grid of lights). The bottom suddenly dropped out and the entire ship started shuddering as the blades went in an out of a stalled or zero lift state. Recovery was textbook and we lost about 200' feet.

How to recover in something like this proposed VTOL will be a large hurdle to surmount for certification and for overall safety of the design.

Paul A.
(Knocking the dust off my CFI-Rotorcraft...)
Jupiter, FL

Thanks Paul, I added that statement only because I understood that the Osprey had that recommendation added to its operation requirements.

Who knows, having propellers on 3 different horizontal planes during hover and that are so spread out versus their diameter, could reduce the chances of vortex ring state significantly.

In any case, we are talking about a condition that seems common to VTOL and helicopters which tells me that there is no reason to stop the development of my design due to some foreseeable consideration.

The proposed full scale vLazair would be an LSA with minimal certification issues.

Dale

"Who knows, having propellers on 3 different horizontal planes during hover and that are so spread out versus their diameter, could reduce the chances of vortex ring state significantly."

Take into account the interaction between the upper propellers/rotors and the lower with wind affecting the downwash angle. To my eye, you could easily end up with blanking of the lower rotors or unpredictable changes in angle of attack with any wind.

Good luck. It's fun to solve problems.