Originally Posted by JD-Slow-Thumbs

So far, all of the serious wind tunnel studies that I have heard of have the KF-Step-Airfoil perpendicular to the main airflow, which I predict would have no / insignificant span-wise airflow.

Ah but that's the thing, it seems to from what some people have done (albeit not wind tunnel, or else, I'm thinking real flight with tuft on wing and camera)
The reality is we don't have enough studies to really know one way or another at this point. As for me I "suspect" it has significance.

Originally Posted by basicguy

MV
What make you think that I built and tested the planes incorrectly or that you have insight in my knowledge or ability yet somehow the straight wing KFm wings glide 25% longer. I don't need a wind tunnel or stopwatch for that. Perhaps it is magic.

This:

Originally Posted by basicguy

Build two wings from the same basic wing design Make one swept and the other straight. See how long they glide.

And you're right I don't know nor have insight into your knowledge or ability, so never mind and carry on.

Quote: Does a straight wing with a traditional airfoil have a better glide than a sweep wing with the same traditional airfoil profile?

Yes,

Originally Posted by Whiskers

Quote: Does a straight wing with a traditional airfoil have a better glide than a sweep wing with the same traditional airfoil profile?

Yes,

Then why sweep the wing? Tip stalls are more likely with a swept wing, right?

Sweeping the wing makes the chord longer for the same amount of wing area. That gives the CG a wider range from front to rear. I like it because I don't have to be as precise when slapping a battery in.

Swept wings also contribute to yaw stability, which is important for planes without a tail like flying wings.

With a swept wing the flow tends to 'slide' off towards the tip. Reducing lift significantly.
Yes speed dependant of course.
But few to No such issues exist with a straight wing

There can be a positive side to having a vortex generating device. This link explains some of the ways it can be employed.

http://www.aerospaceweb.org/question...cs/q0228.shtml

We never doubted the KF Facts from the beginning ( we bought the book !!! ) and have been rewarded with many Simple and Fun flying planes, as my few pages here can attest ... In essence , IT WORKS Great !!! ... We’re Very Happy !!!

Originally Posted by gpw

We never doubted the KF Facts from the beginning ( we bought the book !!! ) and have been rewarded with many Simple and Fun flying planes, as my few pages here can attest ... In essence , IT WORKS Great !!! ... We’re Very Happy !!!

Thanks, GPW.

Whenever you introduce a new idea into the world, at that moment you have also created the opposition to that idea. We have all experienced this at some point in life. However, there are always those who are willing to give that idea a chance and find out for themselves. You are one of those people who were open from the beginning and gave the KF a shot. I thank you for that.

~ Dick

Au contraire .... THANK YOU !!!!!!!! ~ Glen

http://www.bionik.tu-berlin.de/user/...rag/sld021.htm

It would be interesting to do some experiments with Eddy Flaps. For models and other low speed stuff, like Hang Gliders.

They need to be made using a porous material, like silk or "perforated plastic".

Given two wings, one straight and one swept, with otherwise identical geometry and section - both will generate the same lift but the swept wing will always have greater induced drag because it has a lower aspect ratio.

As pointed out by SirRexAlot (above) sweep has other advantages.

Crane

A swept LE produces a dihedral effect.

As concern the KF airfoil, it worked for me in an 'oranges to oranges, apples to apples' 'powered' airframe comparison. Although, with my slope wings, it was best in big wind with lots of ballast.

That's all I need to know, plus, GPW knows best.

I have a question about the maximum power that folk have used on KF foamie designs to date.


Specifically, I'm searching to find any examples of KF foamie designs with brushless motors (or IC) rated at higher than 1000 Watts.


What I suspect is pretty much all powered KF foamie designs use much smaller motors. But I don't know roughly where the (power) limit presently lies.


If you'd like to post a reply, I've started a new thread here (I didn't want to hijack this thread with questions about power on KF foamies):-


https://www.rcgroups.com/forums/show...ils-HIGH-POWER



Thanks!

I'm sure it has been done, to use 1000W would require a motor that weighs about 350-400g or so and was running at it's continuous rating. It would be a large highly powered aircraft and the wing spars and adhesives would have to be good but it would not out of the question to do it.

Jack