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goney3

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I have the latest XFLR-5 thank you. I am talking about so called form lift vs form drag. Like in Wortmann FX 63-137 they have L/D 137 at 2,5 AOA @ 1 mio Re.

Anyhow...what I discovered is is that when you put a man like me flying the HPA ( 260 LBS ) you need to make craft at least an 70-80 pounder.

This way you start to create some believable speeds like 15 m/s...it is a huge difference in lift between 12 and 15 m/s.

Also you can design the entire aircraft make lift ( using the knowledge by DeMonge and Burnelli ). Kinda like a recumbent. This way the entire drag of the "man-box" disappears as it will be part of the lift equation.

Prop being 2.8 m is enough.



Having the wing area like in Musculair 2 is not enough, but lifting fuselage derivation will add amble of lift in ground effect.

I would also take the measures from the prehistoric bird above for span vs length ( 5:1 ).

Main idea is increasing lift area thus diminshing the induced drag....parasitic drag does not increase.

------

I tried to beat the Wortmann foil with mine but "only" got L/D 142 at @ 1 mio Re.

Looks like the Lissaman 77xx(ish) is very efficient.

My apologies then, you must have posted an old screenshot of XFLR5 then, as it shows 6.48 in the corner and latest is 6.57

The drag you mention doesn't seem to be calculated correctly, after all there is no free lunch in physics. 🤔

Have you checked out the Ultralight Airplane Workshop at all for tutorials on this stuff? I apologize if you're an aeronautical engineer, I just found it very helpful is all.
 
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Sraight'nlevel

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Nov 4, 2021
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371
My apologies then, you must have posted an old screenshot of XFLR5 then, as it shows 6.48 in the corner and latest is 6.57

The drag you mention doesn't seem to be calculated correctly, after all there is no free lunch in physics. 🤔

Have you checked out the Ultralight Airplane Workshop at all for tutorials on this stuff? I apologize if you're an aeronautical engineer, I just found it very helpful is all.
Sorry indeed I have old version...I had no idea there is yet a newer one.

Which drag do you refer to ?

I have studied fluid dynamics in the university, but I don't claim to be an aerodynamical engineer.

I would concentrate in the drive train....there is much left to be done in HPAs.
 
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henryk

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Location
krakow,poland
How do you make them oscillate ?


=russian discovery...


or Boldyrev oscillating slat= ( Cl =7 !!!)

PSX_20200926_214309.jpg

.

 
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goney3

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Messages
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Location
Lompoc, CA

=russian discovery...


or Boldyrev oscillating slat= ( Cl =7 !!!)

PSX_20200926_214309.jpg

.

Did I get my Google Translator correct for this one?

BoldyrevsSystem_Oscillation.png
 

goney3

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Supporting Member
Joined
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Messages
36
Location
Lompoc, CA

=russian discovery...


or Boldyrev oscillating slat= ( Cl =7 !!!)

PSX_20200926_214309.jpg

.

The Russian micro-UAV sure ended up looking a lot different than that diagram...
voronkov7_fmt.jpg
 

henryk

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Messages
7,314
Location
krakow,poland

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nerobro

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Nov 6, 2011
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Location
Northern Illinois
Kevlar has to be pretty robust to survive.

Titanium is only 0,27 kg.

Kevlar.. is exactly that. That chain is 110 links? You'd need at least four of those to do something for a human powered plane. No. A metal chain isn't going to beat a kevlar.

Well...everything that we know is very limited...as this test shows us...one thing is for sure...you need a sizeable prop:



Are you under the impression that the car in that video is human powered?
 

Sraight'nlevel

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Nov 4, 2021
Messages
371
Kevlar.. is exactly that. That chain is 110 links? You'd need at least four of those to do something for a human powered plane. No. A metal chain isn't going to beat a kevlar.



Are you under the impression that the car in that video is human powered?
No I am not...saying just that even professors know very little about mechanics, mathematics and aerodynamics...when they all are combined to a one renevable energy system.
 
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