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Apr 24, 2019, 05:24 AM
gpw
gpw
“There’s no place like Foam”
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Guys , if you have the time , we’ve been using Glidden Gripper to laminate the KF strip(s) to my wings …. lightly coat both sides , let sit a few minutes , then stick it together ( Newton clamp) and wait a week for it to cure … Very strong !!! The trick is to make several wings in advance … ( planning ! )
Latest blog entry: Lost plans
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Apr 24, 2019, 06:37 AM
Jack
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Have not tried the new clear glue yet but the classic old brown and the newer opaque quick glue work fine as you describe:

https://www.gorillatough.com/products/#filter=.glue

And for how glue the Arrow slow setting for woodworking is my choice, not the cheap Chinese sticks:

https://www.lowes.com/pd/Arrow-24-Pa...Sticks/1043701

Look at the build images on my blog page and you'll see both of those in use. The hot glue is the ticket for gluing tape covered parts together, like a vstab onto a hstab...

And the tape is the 2 mil or 2.2 mil or so colored package sealing tape applied directly to the plastic membrane side of FFF or applied as you describe above with water and glue to the bare foam side of FFF.

Jack
May 01, 2019, 09:24 PM
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Dickeroo's Avatar
Thought the KFers might find this document interesting. Employing the KF vortex concept to a Darrieus Wind Turbine, it produced a 13% improvement over the conventional airfoil in the post stall phase. This paper was just published. I think it’s on page 35 under 2.8. Innovative Darrieus Turbines.

2.8. Innovative Darrieus Turbines
The continuous research on the Darrieus turbine has yielded many innovative designs, yet a very few concepts have the potential to be scaled up for commercial purpose. These turbines are optimized for low wind speed and are economical. An airfoil that is capable of maintaining the lift over high AoA without significant increase in drag will be an apt choice for Darrieus turbines. Airfoils are modified such as trailing edge cavity modification [64] was found to enhance energy yield. Kline (KF) conceived airfoils with abrupt discontinuity claiming to have enhanced lift. Though the airfoil doesn’t outperform in the pre-stall region, it demands attention for its aerodynamic behaviours in the post-stall region when the step is located on the suction side of the airfoil as reported by Mishriky. The new airfoil KF-N-21 was created by introducing the step discontinuity borrowed from the KF airfoil on the suction side of the NACA 0021 airfoil. In order to create maximum drag during the reverse flow to aid in the startup, the depth of step is located at 18%c, while the maximum thickness of airfoil is 21%c. The step length is 50%c and originates at 30%c from the leading edge, though location near to the trailing edge is favourable for high lift coefficient. The experimental comparison with conventional turbines reveals that the turbine Cp has been increased by 13% at low Re.
Last edited by Dickeroo; May 02, 2019 at 04:38 PM.
May 02, 2019, 07:37 AM
He who stalls....falls!
Quote:
Originally Posted by Dickeroo
Thought the KFers might find this document interesting. Employing the KF vortex concept to a Darrieus Wind Turbine, it produced a 13% improvement over the conventional airfoil in the post stall phase. This paper was just published. I think it’s on page 35 under 2.8. Innovative Darrieus Turbines.
Very interesting.
Would imagine some serious testing happened .
If one industry is taking a look, what others will follow.

Just a thought (probably already mentioned somewhere here), if the KF works well as a "driven" force,
ie- our wings and turbines driven by airspeed, does it also work as a "driving" force? ie- impellor blades,
auto-gyro blades etc.
As I said probably covered, only reading a few pages at a time, the whole concept and history of KF to me
is nothing short of fascinating.
Anyhow, time to get back to depron cutting, and a rest from thinking too hard.
cheers
May 02, 2019, 11:56 AM
Thermite + ice = Big boom.
boaterguy's Avatar
That would be interesting for multirotor propellers, which I imagine are at stall speeds very frequently. a KF lip might show some performance increase in the low end.


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