About

Gender

Male


Location

Saratoga, CA


About Me:

engineer with interest in anything that flies.


Please tell us a bit about your UAV interest

mainly interested in airframes and the "system" aspect of UAS with an emphasis on efficiency. more interested in data than what is "cool"


Hometown:

originally from Paris, France


Activity Feed

frederic reblewski commented on Patrick Hanley's blog post Hanley Innovations Upgrades Stallion 3D to Version 5.0
"@patrick, your softwares are excellent ( I have a multi element airfoil licence that I acquired when the price was lower!) but they are beyond what an individual can afford. I understand you try to protect your revenue stream, but it would be great…"
Jul 19, 2017
frederic reblewski commented on zhangqi's blog post Flying over sea with H2 hybrid powered drone
"@zhanggi
with a small piece of paper, high school math and physics and a pocket calculator you can compute approximates for a lot of physical data!
my comment on flexibility was that your current system is about 2KW so, on one end, if the need is,…"
Jul 16, 2017
frederic reblewski commented on zhangqi's blog post Flying over sea with H2 hybrid powered drone
"with a back of the envelope calculation, it should use around 2 liters of gas per hour, which means that durations above 15' benefit from that approach for that configuration. the main drawback is that there is little flexibility in the power…"
Jul 15, 2017
frederic reblewski commented on Bart Theys's blog post Which one has the highest range: VTOL, helicopter, multi-rotor (or flying squirrel?)
"@Gary. is that the "wing" project you are talking about? I read some rumor but from people directly working there it is business as usual..."
Jan 12, 2017
frederic reblewski commented on Bart Theys's blog post Which one has the highest range: VTOL, helicopter, multi-rotor (or flying squirrel?)
"interesting study!
I have approached the efficiency problem from the fixed wing point of view.
first I came to the conclusion that the range is not the factor to optimize I prefer the range x speed. you want to fly far and fast. optimizing is always…"
Jan 12, 2017
frederic reblewski commented on Colin Snow's blog post Why I Think the Prosumer Drone Will Never Die
"never is a long time, especially close to the end...;-)"
Oct 26, 2016
frederic reblewski commented on moglos's blog post Anatomy of a 425km Flight
"@Andrew Rabbitt. I would be interested too to see your approach of the climb and glide.it seems you consider the gain comes from the better efficiency of the propeller in climb vs cruise. why would that be?"
Sep 15, 2016
frederic reblewski commented on moglos's blog post Anatomy of a 425km Flight
"I answer to myself on flying in circle. from the picture of your flying site I see that the radius is about 600m, which means that at that speed it is about 2N centrifugal force. the average banking is then 2 degree which result in a difference in…"
Sep 14, 2016
frederic reblewski commented on moglos's blog post Anatomy of a 425km Flight
"impressive, congratulations!! I wonder if you have compared flying in circle with a rectangular path. in theory flying in circle is a little bit less efficient as to generate the lift to offset the weight you have to either fly faster or with a…"
Sep 14, 2016
frederic reblewski commented on Ben Dellar's blog post 100km in the X-UAV Talon
"@Damian, I do not understand. you say that the plane would fly faster that the pitchxrpm speed. I thought it was never the case and that the propeller <100% efficiency was coming from the fact that it was "slipping" and so the pitchxRPM was always…"
Sep 11, 2016
frederic reblewski commented on Ben Dellar's blog post 100km in the X-UAV Talon
"as for the 3S vs 6S, I think the only real advantage is to lower resistive loss. very rough evaluation:  if during cruise you are @ 100w and your total resistive path ( batteries, contacts, cables, on resistance of the Fets, motor ) is 0.1 Ohm…"
Sep 10, 2016
frederic reblewski commented on Ben Dellar's blog post 100km in the X-UAV Talon
"@ Damian, I am curious. where does the 70W come from?with 20AH and 3S you have around 800KJ. the flight being 100min that's about 130W average power? if your assumption is true on the L/D ratio the mechanical power needed is DxV so around 33W the…"
Sep 10, 2016
frederic reblewski commented on Randy Sonnicksen's blog post Full Scale Quad - I Frame Design
"why not?
more complex
more expensive 
heavier
less reliable
less energy efficient
drive system from a central engine = lots of destructive vibrations
...


in fact one could claim that the only multicopter advantage is mechanical simplicity thanks…"
Mar 31, 2016
frederic reblewski commented on Martin Rüedi's blog post EASA European regulation proposal
"does it mean that normal RC airplanes will be now limited <50m altitude? that would be the end on the hobby. try to do a loop with a 2.5m wingspan airplane and stay under 50m or fly a sailplane under 50m...nonsense... if the next slice (50->150m) is…"
Oct 18, 2015
frederic reblewski commented on Doug Hunsaker's blog post Short Course on Mission-Specific Aircraft Design
"looking at the spreadsheet the overall drag is just the zero lift drag ( considering that it is a coefficient for the full airframe with the wing area as a reference area?? ) plus the induced drag. I do not know how the zero lift coefficient is…"
Oct 10, 2015
frederic reblewski commented on Doug Hunsaker's blog post Short Course on Mission-Specific Aircraft Design
"@jerry I dont get your comment about efficiency?? the 40% is supposed to be what is left in mechanical energy from the electric energy straight out of the battery: battery restitution, cables, ESC, motor, propeller represent 60% loss"
Oct 10, 2015
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