Does anyone know if the RP-4 is still a work in progress, or has that unusual "twin" project been dropped? I've seen discussions of it on the 'net going back to 2002 and before with photos.
Disturbing that these same photos are all we've ever seen of it over the years. Is this Wildfire-lite? I saw a thread on this topic posted in the AAFO forum in September, but nothing new was mentioned. Did it vanish?
Details and (old) photos via the following link:
My opinion? Just looking at the plane and it's "revolutionary" unducted prop makes me shake my head.
I see potential problems just viewing the photos. An unducted prop may work well when made large enough for a major airliner, but shrinking the design doesn't always work, since you aren't also shrinking the size of the air molecules as well. Air densities and air flows do not feel and act the same at significantly smaller scales. This is one reason why some of the more accurate scale wind tunnels run while pressurized, run super-chilled air or utilize specific gasses, or even used all of the above!
The smaller span blades of the RP-4 will have to spin much faster than their larger cousins to move enough air to do any useful work, potentially taking them into the region of supersonic blade speeds, and thus suffer loss of thrust.
That won't work if this is the case. He'll need to install larger span blades to reduce prop RPM. He still has 5000 hp to work with, IF that claim holds up.
Disturbing that these same photos are all we've ever seen of it over the years. Is this Wildfire-lite? I saw a thread on this topic posted in the AAFO forum in September, but nothing new was mentioned. Did it vanish?
Details and (old) photos via the following link:
My opinion? Just looking at the plane and it's "revolutionary" unducted prop makes me shake my head.
I see potential problems just viewing the photos. An unducted prop may work well when made large enough for a major airliner, but shrinking the design doesn't always work, since you aren't also shrinking the size of the air molecules as well. Air densities and air flows do not feel and act the same at significantly smaller scales. This is one reason why some of the more accurate scale wind tunnels run while pressurized, run super-chilled air or utilize specific gasses, or even used all of the above!
The smaller span blades of the RP-4 will have to spin much faster than their larger cousins to move enough air to do any useful work, potentially taking them into the region of supersonic blade speeds, and thus suffer loss of thrust.
That won't work if this is the case. He'll need to install larger span blades to reduce prop RPM. He still has 5000 hp to work with, IF that claim holds up.