It seems you did not yet read the DEVICE TECHNICAL REPORT for the Portable Flyer as filed in the GoFly / BOEING contest (https://www.pattakon.com/GoFly/DTR_1.pdf
) wherein the same thrust calculator is used:
Quote from the above DEVICE TECHNICAL REPORT:
FLYING AND CONTROL
Limiting the tip speed (of the 39’’ diameter
propeller) at only 150m/sec (45% of sound velocity) for “quiet” take off, the resulting propeller rpm is 2,900rpm.
With 28’’ pitch
and 3 blades per propeller
, the static thrust at 2,900rpm is calculated (with the http://www.godolloairport.hu/calc/strc_eng/index.htm propeller thrust calculator
) at ~75lb (~35Kp, 350N), while the power absorbed by each propeller is calculated at ~15bhp.
At the “quiet” take off, the total upwards thrust is 4*75lb=300lb (136Kp, 1360N); with a total weight of 250lb (114Kg, 1140N) this means ~0.3g upwards acceleration; the required power per engine is 2*15bhp=30bhp. With 2.4:1 “crankshaft to propeller” reduction ratio, the 2,900rpm of the propellers at the above “quiet” take-off, translates into 7,000rpm for the engines.
. . .
(at emergency, or from distant / unpopulated areas etc)
With both engines running at 9,000rpm, the upwards acceleration at a “fast take off” is more than 1g (10m/sec^2)
; it is like “falling towards the sky”. Alternatively: the PORTABLE FLYER can carry two persons (the pilot and a passenger); in this case at a malfunction of the one propulsion unit, the emergency landing is not possible without opening the parachutes.
End of quote.
Even if the actual thrust were only 50% of what the “thrust calculator” gives, the Portable Flyer would still be capable for a fast vertical take-off.
For the rest issues you mention (pitch, yaw and roll control, stability etc, etc), do read the above DEVICE TECHNICAL REPORT, then try to figure out how Yves Rossi,
and Zapata, Mayman, Browning:
control their JetPacks on the air, and then ask anything you can’t get.
Does anybody know what happened with the 125cc RCV (rotary cylinder valve, PGO Scooters of Taiwan)?