DH 82 Tiger Moth ...

[jcf]

... and the thermojets as used in the Campini-Caproni, Mig and Sukhoi aircraft
used a multistage compressor with burner cans mounted behind the driving
engine and exhausting straight through. None of which were features of Coanda's
design. Take a close look at the info out there and Coanda's patents, particularly
the ones that were modified after the fact, and you'll see his design had no hope
in hell of working, and that his claims of flight, made decades after the supposed
event and unsupported in records of the period, were just that, claims without
evidence. The physics don't work.

[GTX_Admin]

Scale the fan up to adequate size for a real aircraft and you start running into problems at that RPM, like sonic tip speeds and all the problems from that.

Yes, unfortunately as all too many have found out, some things don't scale well (e.g. XVF-12).  This is part of the reason that real engineering uses measures such as Reynolds numbers and the like - these give better representations than simply linear dimensional scaling.

[Silver Fox]

I wonder if you could use a matrix of smaller fans? Say one large fan to feed a number of lower diameter ones that avoid the inherent problems?

Engineering nightmare, and I'm not sure what advantages it might offer... but if you were insane enough?

[Silver Fox]

Yes, unfortunately as all too many have found out, some things don't scale well (e.g. XVF-12).  This is part of the reason that real engineering uses measures such as Reynolds numbers and the like - these give better representations than simply linear dimensional scaling.

The best scale for testing has always been 12"=1'. :)

I always run into this issue with my model ships. Water doesn't scale, so how do you make a destroyer look like it has that typical "bone in it's teeth" at high speed? So far, nothing I've seen tried has ever worked.