Windrider Fox - Page 149 - RC Groups
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Mar 29, 2012, 10:29 PM
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mine has the CG @ 42mm
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Apr 03, 2012, 05:17 AM
Urban sloper
GentlemanRider's Avatar
Originally Posted by ferincr
mine has the CG @ 42mm
Same as mine. I started at 560 gr and later ballasted (steel rod in the wings instead of cf one, lead in the nose for compensation) to 650. Now it's WAY better in nice breeze, without noticeable difference in weak conditions.
Apr 03, 2012, 10:23 AM
Space Cowboy
ShoGinn's Avatar
After putting my CG at ~1.5" it is a much better performer, Far more predictable.
Apr 03, 2012, 01:49 PM
Registered User
Originally Posted by ShoGinn
After putting my CG at ~1.5" it is a much better performer, Far more predictable.
In my opinion (and this is just what it is) I think you went from having it too far back to too far forward.
But if you like it this way great.

As far as ballast...
You'll also see different aproaches, some people like it heavy (but then you have to do something to stiffen it up).
I like mine light so I can fly it in light conditions, but I have other planes for heavy winds although I've flown my WR Fox comfortably in winds of 30+mph
Apr 06, 2012, 04:12 AM
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Ben D Wing's Avatar
A cautionary note: I've had a Windrider Fox for some time now and it's generally been flown off the slope, but has recently been used for aero towing.
BTW, the plane has never been crashed, is built as a standard glider and uses no ballast. Anyway, during an aero tow session (the last as it happened) the port wing folded about mid span and the subsequent crash wrote the airframe off. The tow plane was a 1.4m span EPO MX-2 modified for towing so the stresses on the Fox during these sessions were not excessive. The autopsy showed that the main carbon tube spars in BOTH wings (not the wing joiner) had crush marks top and bottom in line with the small chordwise slots in the wing surface. I can only assume that these slots are where the spar is held by a jig during the moulding process and this is what has weakened the structure. As an experiment I tried a bending test on the starboard spar and it took surprisingly little pressure to snap it at one of the afore mentioned marks. I don't know if this is a one-off bad example, or if all Foxes are like this. All I will say is be careful how much ballast you fit and don't pull too hard in a loop or you may have problems.
I will post some photos later to shows the marks on the spars.
Apr 19, 2012, 11:16 AM
Registered User

Thoughts and a few questions...

So after struggling a bit with my Fox... I took some time, re-read through this thread and a few others and made a few changes that have helped tremendously. Thank you!!!

First I just got a 9x radio so I can make adjustments to D/R and such at the field (my old radio required I be in front of a PC to make those changes ...don't ask). So that's a HUGE improvement.

My Fox is chunky at 26oz, and the CG is currently at 42mm - and this seems to best I've had it. Mods: several carbon stiffeners in the wings, control surfaces are balsa, and the wings are covered in packing tape.

My challenges were with some severe tip stalling. I'd gently shift the stick to one side and she'd just dump into a spiraling dive... I also noticed that unless there was a lot of air moving over the wings, she's just start to gradually descend - nose slightly down. She is NOT a floater.

I fist reduced all the throws via a dual rates switch - ailerons to 65%, and elevator to 40%. This helped tremendously!

Yesterday I few in 20-28 mph winds and it was great! I'm thinking that at this weight - she just needs more wind to stay aloft... those wings don't generate a lot of lift compared to the slower ships I'm used to. When she has some airspeed though - what a pleasure!!!! She was still not what I would call docile - but much more manageable. Next, I'm going to increase the ailerons to 70% and leave the elevator alone.

Things seemed to be more difficult (she would start to tip stall...) as the wind got lighter... I'm thinking that at this weight it is just not suited to lighter winds. I'm fine with this - but would be interested to hear others' thoughts.

My next question is about differential. I've never played with it before (I'm a perpetual Rookie ) and thought that it might help improve things as some have indicated in this thread. All I know is that it is difference in up v. down - I'm assuming () this is usually just used on the ailerons? I'd love to know just how it effects the handling of the plane.

Is it typically more up than down?

Where do folks suggest I start?

I eagerly await your thoughts and advice.

Apr 19, 2012, 11:54 AM
Registered User
I've flew my fox in almost no wind and it as never even come close to tip stalling it will just gently nose up and down to let you know that there's not enough lift.
Mine is also covered with fibre tape wings tail and fuse and I put just a little extra carbon in the wings to try and keep the flexing down to minimum..this had limited success.
Auw is about 22ozs (I think its been a long time) I also have a 5 oz lump of lead that I've shaped its fits into the wheel space (with the wheel taken out) so this takes me to about the same weight as yours or maybe a little heavier and it flys great with this little bit of ballast.
I did post a short video up I think it was on this thread of the Fox flying in almost no wind maybe 5mph and it was up for quite a while.
Alll I can think of is the slope your flying off maybe it just isn't generating enough lift in the winds you've been flying in.

Apr 19, 2012, 12:28 PM
Registered User
Originally Posted by catfish
Alll I can think of is the slope your flying off maybe it just isn't generating enough lift in the winds you've been flying in.

While it is possible, when I took the Fox to a very popular slope site near Golden (Mt. Zion) and there was plenty of lift it did the same things... Folks were flying other planes (there was a Moth, a couple of Bees...) with no problem.

Apr 20, 2012, 04:00 AM
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serjuro's Avatar
Hi there,
In the begining I've had the same horific tipstalling at slow speeds and steep turns with ailerons....
I have built ailerons from balsa sheets, played with the CG but the real problem solver was the horizontal stabilizer...
From the factory, it has about 2 degrees down the floater ships.... This in fact raises the nose and the incidence of the main wing for lift....
At this glider, it reduces speed fast and thus the tipstall.....
I glued the horizontal stabilizer at about zero degrees and from this point the glider became very tame and predictable....

Speaking of aileron differencial, I use 50% down and 100% up....for general flying.
For aerobatics I use 100% up and down aileron throws...
Apr 20, 2012, 04:58 AM
Woodstock 1's Avatar
I have a suspicion that not all Foxes are the same, probably due to the material it is made of. Many report impeccable behaviour right out of the box and built stock, others seem to find there is a decalage problem. This sounds a lot like the Radian thread: Paul Naton found the decalage on his to out, others have no problem. Foam is the common denominator here: it's possible that inaccuracies can creep in with such a material, and also in the assembly.
Apr 20, 2012, 05:52 AM
Registered User
Hm ..very interesting that would explain it, I think mine comes under the catorgory of impeccably behaved I have a few models that do ok in light lift but when they start to struggle I just toss the Fox out and it as never let me down.
It does what it was designed to do fly well in light lift conditions ...well mine an after thought here's my Fox
when my other models didn't want to play I think this proves the point I was trying to make.

Windrider fox no wind.AVI (1 min 32 sec)
Last edited by catfish; Apr 20, 2012 at 06:00 AM.
Apr 20, 2012, 12:11 PM
Registered User
Thanks for the video. I watched and thought of many places where mine would simply dip into a death spiral in those light conditions (like the steep bank at :16). Your point is clear ... and I at least know that the Fox CAN fly under lighter conditions - now I just have to figure out how to make that happen. Indeed you have a lovely place to fly...

Thanks for all the replies in fact.

Serjuro, I will take a close look at the incidence of the h-stab. It certainly make sense and may very well be a (the) significant culprit. Particularly when I think that when there is a lot of wind - the Fox isn't anywhere near stall speed ... so it isn't an issue. Reduce the amount of air flowing over the (narrow) wings and now ... well, "Houston we have a problem..."

I played with differential (100% up, 55% down) on my last flight and it seemed to help noticeably. The wind was pretty good so I'll be curious to see how it does in lighter air. For now I'm going to keep it where it is as it is a step in the right direction.

Woodstock, I've got a Radian and actually did the Mods before ever flying it (I did check the incidence and it confirmed Paul Naton's observations for my plane as well). That plane flies perfectly ... in fact it flies so well, that I think it has me a bit spoiled . I need to remember that none of my other planes can fly that slowly and be that so stable.

The forecast for the next few days is for very light winds - so the Alula, The Radian and the Mini Topsky will be getting some airtime and I'll be making a few measurements and then, likely, adjustments to the Fox's incidence.

Once again, I so appreciate your help and thoughts as they have helped me become a better pilot and builder (at this point more that latter than the former ) - and most importantly learning from others who have so willingly shared their ideas makes it more enjoyable!

I will report back on my findings!

Last edited by WH Rookie; Apr 20, 2012 at 12:20 PM.
Apr 20, 2012, 06:12 PM
Registered User
Steve, also have a look at this:, might be worth a try.

Apr 21, 2012, 12:03 AM
Registered User
Originally Posted by flarssen
Steve, also have a look at this:, might be worth a try.

Thanks for posting that! I recall reading about the zigzag tape when reading this thread... (I have read it all actually). I'd forgotten about it though.

I've gone and repositioned the stab ... It was a couple of degrees off so I sliced out a thin sliver of foam on the bottom of the slot and glued it to the top and put the stab back in. I set it at the same angle as the wing so I'm hoping tht will help.

If things are still tough, I'll try some regular tape to try to eliminate that "bubble" on the wing as it appears that it seems to help a lot - just not as much as the turbulator.

The name "turbulator" reminds me of the Turbo Encabulator video... worth a watch if you haven't seen it...quite amusing.

Apr 21, 2012, 09:39 AM
Space Cowboy
ShoGinn's Avatar
The plane does have tip-stall characteristics but it is exacerbated by flying style as well.

If you look at the video you can see he is flying slow and smooth.. this plane hates to be thrown around in light wind. I do agree that catfish has a mild plane as well and i've seen Steve fly his and i'd like to know wing weight on yours Steve to get an idea on why your plane likes to tip stall.

My Wings are ~135g (4.76oz) each with new stuff on them.