If formula is NOT designed for Ducted fan performance calculation - it's can't give acceptable figures.BTW=formula for Kf can help in comparation betwen
two DF with different dimensiones...
Compressor blades are not designed for Ducted fan use - they design for different RPM's and have different twist and installation angel's. Also number of blades is very matters.Still working on my version of this. So far I have data from an 11 inch diameter DF made with compressor blades from a Rolls Royce Avon engine.
Josef Dusek was many years in Australia,good english speeking...On video they don't show thrust measurements, only talking about. But on the video their craft take off and flying don't look like it has 70kg of thrust.
The obvious solution would be to take a jet turbine engine, add a gearbox to turn it into a turboshaft engine, then hook it up to the ducted fan in order to simulate a jet powered aircraft.The key here would be developing a complete powerplant that can be integrated with multiple airframes. Like with electric aircraft, the problem is the lack of off-the-shelf solutions.
5000 rpm is way to low for 11" or even for 17" fan for good performance. Depend on blade design the installation angle should be 35 deg. or less.I just drove the 17" DF powered machine down our taxiway and back and got the fan a bit over 5000 rpm while recorded 55 lb of thrust.
When I was testing the 11" version with the blades at the same angle (~55 deg)as in the compressor they came from I got 14 lbs of thrust at 5000 rpm. I then built a hub with variable blade pitch and at 40 deg the thrust doubled at the same RPM. Twenty eight lbs of thrust on 8 HP isn't all that bad. Hopefully, the 17" fan will behave similarly with a new hub and the just installed 35 HP engine..
https://journals.sagepub.com/doi/abs/10.1177/0954410018774117?journalCode=pigaThis book's have good information for Ducted fan design:
https://www.homebuiltairplanes.com/forums/attachments/11-inch-12-29-19-a-jpg.93768/I am going to take the 17" fan
Look like you have good setup for testing your Ducted fan design. What is your goal - craft, this Ducted fan will be used? Why you decide to install so many blades with low hp engines?I will also be able to get some data at air speeds up to 30 mph
My guess is that HP, RPM, and design airspeed will be needed to make a rough estimate.Here's a question from someone who knows very little about ducted fans....
Setting aside how to build it or how much it costs ore even what engine to use, what would the ideal fixed-pitch ducted fan look like for general aviation use? Let's say a maximum diameter including the duct of 1 m or less, so a fan diameter of 80 cm or less. What would the fan itself look like to get most thrust from a fan that size?
My guess is that HP, RPM, and design airspeed will be needed to make a rough estimate.