Hello all
NAN Models trying to improve each time it’s leading at F5J Gliders have updated the wing panel for Explorer moving the hinges line 2cm more from trailing edge.
This new big flaps wing have better stability, can easy put more camber with less drag and you can easily flight the model in very low speed waiting to catch a thermal, also, model is more “flexible” at low speed with great maneuverability.
It is a great step ahead due to big improvement in handling at low speed.
I have check 4m and 3.8m Explorer with Big Flaps for more than 200 flights and it is awesome

Just too nice. I might have to get me one.

My BF will fly in 2-3 days. Usually I am quite calm about new planes, but I am really curious about this one Never seen NAN making a change that would not actually improve the plane.

Pantelis, it looks like the ailerons are also hinged at the same point as the flaps. Big ailerons.
Do you have to decrease the amount of aileron throw because of the larger area ?

Wow, those are some barn doors, that's for sure.

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Greg

Here are some pictures for comparison: https://www.rcgroups.com/forums/show...4&postcount=26
Aaro

Originally Posted by gdouglas

Pantelis, it looks like the ailerons are also hinged at the same point as the flaps. Big ailerons.
Do you have to decrease the amount of aileron throw because of the larger area ?

Wow, those are some barn doors, that's for sure.

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Greg

Aileron hinges following the flaps hinges so, it's not only big flap but also big Aileron wing tips .
You can decrease the aileron throw, but I am not suggesting this, because you can fly the model with low speed and in this speed condition sometimes you will need big aileron throw.
With 9 degrees joiner model can turn easily with rudder, reducing the drag, and have "clear" wing at turns.
I don't know if someone else have trying something like this, but I had make "tests" mooving only the aileron that I want to turn, keeping the other aileron to zero possition (not moving down) and models turns very good, keeping nose in correct possition on turn.

Originally Posted by dapan

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I don't know if someone else have trying something like this, but I had make "tests" mooving only the aileron that I want to turn, keeping the other aileron to zero possition (not moving down) and models turns very good, keeping nose in correct possition on turn.

That is very interesting. That eliminates the 'adverse yaw' problem of the downward aileron creating more drag and causing the plane to yaw in the direction opposite the turn.

What are your thoughts on the upward traveling aileron only ? Is it something you will be flying with at competitions on a regular basis ?

Also are the large control surfaces something that's going to be done on the F3J Xplorer, or is there some reason (internal structure difference in the wing) that does not allow it ?

It would be nice to see some video of the Explorer flying along at cruise speed, at eye level, and deploying full flaps, to see it stop in mid air and hover like a bird.

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Greg

Greg, seriously, both my (E)Xplorer F5J planes already hover over the landing tape. I will need a fair # of "show me" flights before I buy into this change...

That may be true, Chris. But, NAN does not make changes of this magnitude without a good reason. They have obviously done some testing, and determined that the benefits outweigh the costs of creating new wing molds.

Perhaps we're missing the point, and the biggest advantage is the huge ailerons' improved turning performance due to less adverse yaw. Those barn doors bringing that baby to a dead stop in the air are just a lesser benefit.

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Greg

Perhaps. Another thought from the Captain Obvious department: this puts more force on those little MKS 6100/6110 servos and makes it much easier to drag flaps on the grass. Look closely at the pic in post #1. I have never stripped a 6110 gear.. but this wing would make it much easier. The aero benefit of this change would have to be pretty dramatic.

Larger control surface chords will not reduce adverse yaw, which is mainly generated by the rolling motion of the wing. And trying to use the up going aileron to generate drag on the outboard wing is inefficient, and mostly futile. Reducing the AoA of the outboard panel, which is basically what the up going aileron does, actually reduces the drag of the panel until the deflections get very large, and then the profile drag does start going up but it causes far less drag to use the rudder to counteract adverse yaw.

Dr. Drela's excellent explanations of adverse yaw, and his drawing attached below:

https://www.rcgroups.com/forums/show...44&postcount=8

https://www.rcgroups.com/forums/show...4&postcount=20

As an aside, the Gossamer Albatross man-powered airplane only used downward TE wing warping on the inboard wing to balance the inward roll, and rudder to counteract adverse yaw. It is probably the most extreme example of a slow inboard wing, and the necessity for absolute minimum turning drag.

The free flight guys have been using very wide chord flaps (50%) for many years. I ran many XFLR5 simulations of various flap chords on RC sailplane airfoils, and I believe Gerald Taylor did as well. Unless there is some benefit that doesn't show up in Xfoil, there really isn't anything there that I can see, except maybe for 3D flying. I find it interesting to note that full-size sailplanes use extremely narrow % chords for the control surfaces.

The forward hinge line will likely trip the flow to turbulent earlier than it might with a smooth surface. That might lower the stall speed, and enhance very low speed flight, but a turbulator strip would do the same thing. Unless the airfoil really needed a turbulator, the high speed drag will increase if the flow trips early. XFLR5 is very optimistic on the effect of turbulators, because it doesn't model the drag increase.

Kevin

Perhaps I have missed it here but what local chord percentage was the old one vs the new one? Was the airfoil changed to optimize the new location or was it flight tested and found to be more efficient with a different hinge line?
Great stuff!

Kevin, I agree with everything you said but I do have a remark on the free flight issue since I’ve seen it come up as a “justification” for the big flap concept on more than one occasion.
In the early days of flapped free flight models, especially F1A, big flap as much as 50% of the chord were used but not because they were found to be best but because like everything else in the free flight business, someone thought it was a good idea, did it first and all followed and copied. No one actually tried a different value. They were trying to get “old style” airfoils to launch higher and it looked like the best way to reduce drag, bend the airfoil in the middle to make it as flat and as thin as possible. The structural problems were hard to overcome and many models found a quick death in spectacular explosions during wild launches but when they worked they would launch higher than the unflapped models by a good 15-20 meters. On parallel newer, low drag airfoils were designed and matched the flaped wing models in launch height.
Today, the newer models have a flapped low drag airfoil with a flap just 25% wide and actually launch higher than ever before by another good margin. these new models were actually researched a bit before construction and prove once more that xfoil is actually a pretty descent design tool, even with all its limitations.

As for the Explorer BF, from what I’ve heard, the drive for this design was to get better low speed handling. The foils and wing planform are still the same as when they first came out as the Xplorer 1 back in 2009-2010.

Bigger flaps? I already have more than enough flaps to stop most of my planes dead in the air. Do these light planes really need bigger flaps? I would have loved bigger flaps when I was flying 80 ounce TD planes. But do 45 ounce planes really need them?? I rarely use full flaps as it is.

Mooving only one Aileron it was just for check, just to saw and understand what happen. I was suprised when I saw that the airplane haven't delay to respond at my orders Also, suprised because turn smoothest, but I can tight my turn very easy.
I still flying my "normal" mode mooving both ailerons
NAN models before decide to produce this new Explorer wing version, have made a lot of tests to computer programs but also in to the field in different flying weather.
Those big flaps hovering the plane as an helicopter, but these are not so big for this reason..
Really it was interesting when we had more than 6m/sec wind speed and 4m was stable and penetrated without ballast (Testing model was 1170gr)
As for airfoil is the same as the old (new) Explorer.
Explorer is high quality model with same airfoil for a lot of year because it working great for all weights.
It's obvious that is the best choice for all pilots.