Nasty Toes Foam Wing

An easy way to add a quality wing to your DIY project

I'm experimenting with different wing construction methods and one I tried was the Nasty Toes Foam Wing. These wings are foam and come in four variations – the one I purchased was the Eppler 197. This wing has a surface area of 460 in² / 3.2 ft², which is what I wanted for the model I'm building (I'm a park flyer and I don't want a missile); if needed, you can make it longer by adding other components to it.

The wings come in a large box which, when opened, revealed two large foam blocks:

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Closer inspection showed that the wings are inside the foam blocks:

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Each wing slips easily out of the foam block, as shown below:

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Once out and lined up, looks like a nice wing:

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These wings are each cut 23" long with a 10" cord, has "three degrees of dihedral pre-cut into the root end of each wing half and each half has 3 degrees washout for a more stable flight". It's VERY nice to have all this pre-cut accurately.

The foam used is Extruded Polystyrene foam (1 lb foam – EPS):

Foam

There may be some small voids between cells. The surface should be lightly sanded before doing anything to it – I used 400 grit with a power sander (held lightly). Following directions that come with the wings, I cut out ailerons:

Ail Cut

I then lined up the two wing halves with short pins – I decided to join the wings using carbon tubes:

Pins

The foam is not all that tough to penetrate – I tried slowly drilling but quickly found that it was overkill, so I was able to line up the tubes and push them into place:

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Lined up and ready to go:

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This shows how the two halves line up:

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After a trial fitting, I then epoxied the tubes in place, as well as epoxying the center joint. After five minutes, the epoxy kicked in and I had a nice tight fit with dihedral and washout built in.

One thing I did notice with the foam used is that it is not all that robust – I would be very hesitant to fly with it "as is" without some strengthening. There are a host of techniques for this and, depending on what's used, will add some weight.

As I wanted a strong wing that I could move between models, I erred on the strength side vs lightness. The wing weighed in at about 3¼ ounces and 4 ounces after joining.

I decided to use SIG KOVERALL, a white, heat shrinkable, light weight (1¼ oz/yd) polyester fabric which can be doped, enameled or epoxied to attain impact strength – I used Minwax Polycrylic with excellent results – it's water based, dries quickly, cleans up with soap and water and is not too heavy – three coats seem to give very good results.

This is what the wing looked like after covering (not trimmed yet):

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Once covered, the wing's stiffness was markedly improved – no question that it is MUCH stronger than the bare foam wing. The fabric gives the wing incredibly improved stability in flexing and twisting motions; frankly, I don't know how you could NOT do something to strengthen it. After covering, the wing weighed in at 7.4 ounces; considering its large surface area, not too bad.

CONCLUSIONS

The Nasty Toes Foam Wing (Eppler 192) is a very nice way to quickly add an accurately cut foam wing to your DIY project. At about $20 shipped, it's not unreasonable and saves a lot of building time, although I would be hesitant to use it without some form of strengthening.

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