
DIY puller RC flying wing airplane with Kline–Fogleman modified airfoil - synesso
http://ausleuchtung.ch/kfm2/kfm2-puller.php
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LoSboccacc
some people testing KFm on a large rc I found now while looking for info on
the airfoil itself
[https://www.youtube.com/watch?v=6H-s7yuJcwk](https://www.youtube.com/watch?v=6H-s7yuJcwk)

it's interesting. too bad I couldn't find any video in a wind gallery. (edit:
did my own, not the best software but it's something
[https://i.imgur.com/TudMHlX.png](https://i.imgur.com/TudMHlX.png) \- there's
some lift in there to be had)

Ultimately I'm still unconvinced it works the way they tell it works.

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semi-extrinsic
There's been actual research (incl. by NASA) on the KFm foil (although scaled
up for real airplanes or military drones) which has come up inconclusive.

Just FYI, your simulation looks really underresolved and the leading edge of
the foil should be rounded off. Not intended as criticism, just in case you
want to improve.

If you do proceed to work on this, which I think would be interesting as KFm
in the RC wing size regime seems not so well studied: avoid vortex panel
method and anything else based on inviscid/potential theory, you're interested
in laminar flow for RC applications. I'd give it a try e.g. with SU2 starting
from the laminar flow around cylinder tutorial, and making you own mesh file
for the KFm with gmsh (pretty easy to use mesher with GUI):

[https://su2code.github.io/tutorials/Laminar_Cylinder/](https://su2code.github.io/tutorials/Laminar_Cylinder/)

[http://gmsh.info](http://gmsh.info)

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LoSboccacc
thanks for the pointers! I'm way out of my element here and just thrown
together something with the first software I found on internet.

about this:

> the leading edge of the foil should be rounded off

I agree, however, in the first round of simulations the leading and trailing
edge where they themselves giving a lot of lift to the foil (especially the
trailing tapering), so in my naivety I slabbed both edges to reduce those
effects and see if the flow was deflected by the slab alone.

interestingly, even if the model itself is flawed and the simulation
technicalities off for the intended purposes, having the slab slightly forward
gave also interesting results, almost the same lift and a lot less drag

1) [https://i.imgur.com/TudMHlX.png](https://i.imgur.com/TudMHlX.png) 2)
[https://i.imgur.com/GjiVL8s.png](https://i.imgur.com/GjiVL8s.png)

so I came up with an idea for a foil that's still easy to craft out of foam or
balsa and does use the different effects do redirect the flow more effectively

3) [https://i.imgur.com/n9RUHs5.png](https://i.imgur.com/n9RUHs5.png)

of course all of this is purely based of a low resolution simulation, still,
it was fun. I've no chance to test them in practice tho.

~~~
semi-extrinsic
Interesting stuff! What you need to be careful about when comparing different
foils is to ensure you compare at the same angle-of-attack (AoA). Especially
the latter foil has a high "intrinsic" AoA.

The best way to do it is running simulations that span a range of AoA,
calculating lift and drag for each one, and setting the reference for each
foil at the zero lift AoA. Then you can do a fair comparison.

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fit2rule
I build and fly RC .. and I love the Kline-Fogleman device.

Its so simple, you can teach anyone to build one, and it will fly. Its so
simple, one wonders if it could be the basis of a self-assembly/auto-assembly
art project, whereby raw material is fed into the box, a crank is turned, and
out flies a new airplane. This is a mind-experiment I've been toying with for
a while .. automated assembly of KF-based airplanes.

~~~
StavrosK
Do you have any links? I have a quad and figured I'd build a plane out of the
spare parts, and ordered a Pixhawk, but none of the connectors seem to
actually fit anything else. Am I doing something wrong or are they actually
not consistent? Is there some website that helps you connect the components
and configure the Pixhawk?

Thanks!

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Phlarp
It doesn't look like he is using a Pixhawk? It's hard to be sure but it
appears to be a commodity quad FC, presumably with wing/plane firmware
flashed. Not sure which flight control firmware varieties still support planes
and wings since the ones I've used haven't had support for that in years.

~~~
diego
That's not a flight controller, it's a simple power distribution board, most
likely [1]. Flying wings generally don't need flight controllers, they just
need two servos and an electronic speed controller for the motor. A flight
controller is nice because it can stabilize the plane, and it can also provide
autonomous flying it it has a gps. If you just want to fly around like that,
no need.

[1] [https://images-na.ssl-images-
amazon.com/images/I/61k-Sva2oYL...](https://images-na.ssl-images-
amazon.com/images/I/61k-Sva2oYL._SX569_.jpg)

~~~
StavrosK
True, he just uses a power board. I went full hog and got the ArduPilot board
plus the telemetry transceiver so I can have the plane fly from the computer
with waypoints. Now if only I knew how to connect everything!

~~~
fit2rule
You'd be far better off scaling things back a bit and just learning
traditional RC electronics - how an ESC gets wired up to the motors, where the
servo's get their signals, and all that. ArduPilot definitely has sex appeal -
but learn the basics of RC electronics first, is my advice ..

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akavel
Related, also a DIY flying wing, but non-RC, _full size:_
[http://www.facetmobile.com/](http://www.facetmobile.com/)

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avmich
This is "flying body", not flying wing - the idea is to "remove body" in one
case and "remove wing" in the other.

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jaytaylor
Looks like a fun project!

Imagine a version of this with forward-facing and bottom-facing cameras which
transmit back in real-time.

Seems like it'd be a sort of holy grail for the vehicle class.

~~~
walrus01
For basic FPV (first person view) the camera and transmitter to do this is
super cheap now. At the low end they've become commodity items used in small
quadcopter drone racing.

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perk
Cool! I want to build this but I don’t have any spare parts. What do I need to
buy?

~~~
htgb
Flite Test [1] has a ton of good articles and videos, from beginner to
advanced level. This is a good place for getting started with the hobby.

At least a couple of years ago, Hobbyking [2] was the most popular webshop for
buying all the parts. It's a Chinese company, and shipping is a decent
proportion of the total price, so keep that in mind when looking at prices.

[1] [https://www.flitetest.com/getting-
started](https://www.flitetest.com/getting-started)

[2] [https://hobbyking.com/](https://hobbyking.com/)

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abakker
I think the Parrot Disco is a commercial drone modeled on the same concept.
unlike other fixed wing drones, they appear to be very easy to fly.

~~~
theothermkn
A quick Google image search reveals that the airfoils on the Disco do not have
rear-facing steps. These steps are the defining feature of the KF foil family.

