Thread Tools
May 21, 2009, 04:46 PM
Registered Plan-a-holic
Hepdog's Avatar
Quote:
Originally Posted by magic612
Another question: Why not put a step on the KFm closer to the LE then? Why not at 20% or 30%? Has anyone tried that? What's the effect?
I think this has been a trial and error type deal. As mentioned the KFM wing seems to make the best lift/drag compromise with it around mid chord. Ironically full laminar airfoils are also usually thickest at or very near mid chord. Don't have a wind tunnel - just what we've seen.
Sign up now
to remove ads between posts
May 21, 2009, 06:23 PM
Bernoulli+Newton=Lift
magic612's Avatar
Thread OP
Thanks for the response, Hepdog. Much appreciated!
Jun 11, 2009, 08:57 AM
Registered User
Sky-walker's Avatar
Best thread on rcgroups(perhaps) I am very interested in how a wing flys and if we know one day for sure we will then have reached a goal, very very far from now here.

my current theory is that all lift or most of the lift is coming from Newton law of reaction. You puch air down, you go up. as simple as that.. the top shape of the airfoil is doing that as well as the air curves around it and dicharges downwards!
Last edited by Sky-walker; Jun 11, 2009 at 09:06 AM.
Jul 06, 2019, 11:56 AM
Registered User
I'm a long way from servos, receivers, etc.
But I have a plan to build a sorta Ugly Stick sort of plane. And I plan to use a KFm-4 on it.
I currently have a Bloody Baron converted to a biplane awaiting power and such. It has KFm-2 wings.

If I ever do get to fly them I will report.
Jul 07, 2019, 09:55 AM
The Junk Man
Quote:
But this is about foam...
Exactly. And foam can easily be made to be SO much more capable than flat plate or KF. Flat plate, well... is flat plate. It works, sorta. KF works but is (IMHO) uglier than a plumber's butt.

Actual airfoils are dead easy to make with a simple drop wire cutter. And you have LOTS of airfoils now specifically designed for low Reynolds Numbers to chose from. Dr. Michael Selig has an entire series of them. Let alone a host of old NACA airfoils that are WORLDS better than a flat plate or KF wing. All available for free.

But that's just me.

Tom
Jul 07, 2019, 12:03 PM
Ft Lauderdale
Number_6's Avatar
Old thread here, but theory doesn't change.
I never tried exact KF airfoils, built a few foam board planes that flew good.
Prefer to hot wire foam now though. Most interesting for DIYers to do the whole process.
YET, hot wiring foam and finishing a wing can't exactly match wind tunnel theory.
By the time we add servos/control rods/ailerons/hinges... the perfect numbers are out the window.
Jul 07, 2019, 12:20 PM
Registered User
I made a 6 inch chord by just a wee bit under 30 inch KFm-4 yesterday. Interested in how it will fly. Sigh.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Jul 07, 2019, 02:35 PM
Registered User
My Arnim fuselage needs Gorilla glue and clamp stuff to be done. I have 2 inch control surfaces taped and glued.
Wish I had red strapping tape but the fuselage is in clear.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Jul 10, 2019, 04:17 PM
Registered User
Was going to go get Gorilla glue and clamping stuff but it is HOT and HUMID out there. Maybe with the truck already cool I'll get that stuff tomorrow.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Jul 12, 2019, 12:54 PM
Registered User
I got a 2x2x36 angle iron. Fit across the bottom just fine but hit the top of the fuselage. We have a Portable Band Saw and while not a beautiful 2x1 it is in the fuselage gluing the joiner in the bottom.
It will be Frankenstick. While my biplane will be Frankenbaron.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Jul 12, 2019, 01:44 PM
An itch?. Scratch build.
eflightray's Avatar
Quote:
Originally Posted by Sky-walker
Best thread on rcgroups(perhaps) I am very interested in how a wing flys and if we know one day for sure we will then have reached a goal, very very far from now here.

my current theory is that all lift or most of the lift is coming from Newton law of reaction. You puch air down, you go up. as simple as that.. the top shape of the airfoil is doing that as well as the air curves around it and dicharges downwards!
You should have a read of this thread in the Modeling Science forum, (but I must warn you it's very long winded, and involves a lot of arguing) ---

Should NASA be teaching incorrect version of lift to our kids?

You may require therapy afterwards

.
Jul 12, 2019, 01:48 PM
An itch?. Scratch build.
eflightray's Avatar
One of mine, 16.5" chord, Depron foam.

Ray.
Jul 17, 2019, 11:18 AM
Registered User
Yesterday I started the process of attaching the upper wing to the Frankenbaron. Hopefully the epoxy holds.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Jul 17, 2019, 12:58 PM
flyin' fool
goldguy's Avatar
My experience is that the wing loading is as important as the airfoil.
Jul 17, 2019, 02:03 PM
An itch?. Scratch build.
eflightray's Avatar
I think it has already been proven that a model the weight of a brick outhouse and similar loading can still fly with enough power.

But then that's the IC engine power forums.

.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
HOW and WHY do you choose a power system for an aircraft? (Antic e-conversion) steve crewdog Power Systems 17 Jun 20, 2005 12:54 PM
Why do you guys hate Clinton so much? windsurfer Life, The Universe, and Politics 152 Sep 10, 2003 11:41 AM
Why do you need insurance TFLG Slope 9 Sep 01, 2003 01:26 PM
why do you need throttle curves jared salbato Electric Heli Talk 6 Sep 25, 2002 02:36 PM
How do you choose an airfoil? DeaninMilwaukee Power Systems 9 Jul 05, 2001 02:26 AM