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TomMcW
TomMcW
00:27
@Wasabi Welcome to the Hangar. Are you real wasabi or the fake stuff we get in the US?
Does anybody understand these rows of vortex generators showing up on the trailing edge of tractor trailer fairings? It seems to me that a vg placed right on the trailing edge would simply increase drag with no benefit.
ymb1
ymb1
01:07
@Wasabi hi there
@TomMcW dunno why, but your question reminded me of this:
user image
and of course it needs that comment:
@TomMcW: Fixed gear, bracing, struts all over the place, and those guys worry about wingtip vortices. Sheesh! — Peter Kämpf Jan 10 '17 at 7:43
on a more serious note:
user image
user image
via: Lo, Kin Hing, and Konstantinos Kontis. "Flow Control Over a Tractor-Trailer Using Vortex Generators." (2016). core.ac.uk/download/pdf/42372267.pdf
TomMcW
TomMcW
@ymb1 I see on that test they placed the vg’s well forward of the trailing edge. The ones I see are right along the trailing edge. They appear to come from a company called Airtabs. They have a lot of fancy-sounding stuff on their site, but nothing that really says how they help.
ymb1
ymb1
to me all three images look draggy :'D maybe a topic for Physics SE?
TomMcW
TomMcW
They say stuff like this: “ Airtabs radically alter the airflow to reduce drag in two ways: Shifting the airflow pattern from vertical to horizontal to eliminate large eddies, and smoothing the airflow to artificially simulate a tapered rear of the vehicle.”
sounds like marketing BS to me.
ymb1
ymb1
the paper I linked, couldn't find a clear-cut conclusion by skimming through it
 
3 hours later…
uhoh
uhoh
03:53
1
Q: Does Ingenuity rotate via differential rotor speeds or differential angles of attack?

uhohI've seen a few photos taken by Ingenuity of its own shadow, and the angle between the two sets of rotors is different in each. That suggests to me that spinning the counter-propagating rotors at very slightly different speeds could make the aircraft turn via some conservation of angular momentum...

ingenuity helicopter
 
13 hours later…
ymb1
ymb1
16:50
@uhoh (Y) and here I was thinking it's just a drone put on Mars :D
 
1 hour later…
ymb1
ymb1
17:55
@uhoh and answered ;) the blog post wasn't authoritative enough for me, although admittedly it wasn't easy to research -- my workaround was to omit the word "ingenuity" from the search
 
4 hours later…
uhoh
uhoh
21:56
@ymb1 Thank you very much! Eight electric motors!!! :-)

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