Wov Carbon Frame - 25/05/2006

The following is a review the Wov carbon frame. I'd like to thank Wov for providing this unit for review.

This carbon frame is somewhat unique amongst its peers. The interesting and attractive element with regard to this frame is that it is made entirely of carbon fibre. There are no aluminium cross members, bearing blocks or tail boom clamps. The whole frame is very cleverly designed and constructive from just carbon fibre and a bunch of nuts and bolts.

So why do this? The answer to this question is weight. In any carbon frame the most heavy components of the aluminium components. In this frame there aren't any aluminium components and therefore it is extremely light.

This frame takes its heritage originally from the Heliup carbon frame but it would be incorrect to say that this frame is a copy of the Heliup carbon frame. In fact quite the opposite. This frame has the same servo configurations as a Heliup frame but from then onwards the similarities end. In reality this frame is very much unique in that nobody else has applied the design effort evident in this frame to create a very functional, superb flying and entirely carbon fibre offering.

The frame on review here is the silver carbon fibre version and it arrived fully assembled, which is an option offered by the manufacturer. Without any actual building of the frame itself to do I immediately set about getting some good pictures of the frame. The only assembly work required is transplanting the internals of the trex from your old frame to the new one.

 

The frame is held together with M2 nuts and bolts. The methodology used to bolt the frame together is quite ingenious and involves the nut being held in a slot in the carbon fibre. The bolt then goes through a hole in the carbon fibre and into the nut. This is quite difficult to explain and easier to illustrate with pictures.

 

The exception to this nut and bolt methodology is the tail boom clamp hich works by squeezing two carbon plates against the tail boom. This time long M2 screws and M2 nuts are used in a more conventional manner to squeeze the plates on to the sides of the tail boom.

 

The boom clamps are actually one area of this frame that although entirely functional I did not feel overly convinced by the solution. My concern was that it can be very difficult to Loctite a very small M2 nut and therefore the boom clamps may come undone. My preference would be to use nyloc M2 nuts on the tail boom clamp bolts. The other item that concerned me was that there is only a small area of carbon fibre actually in contact with the tail boom once it is tightened. This could lead to the tail boom slipping and tail belt tension being lost. In practice the tail boom clamps did not give me much trouble but some extra vigilence is required. I had one occasion when a nut came loose and this was immediately obvious as the tail boom started to rotate. Since then I have replaced the standard M2 nuts with the nyloc variety. Since doing this I have had no further issues with nuts coming loose.

Moving on from the boom clamps. Let's now take a look at how the main bearings are held in place and support the main shaft. Essentially what has been done is that carbon fibre plates have been stacked one on top of the other in order to make a bearing housing. This can be seen in the pictures below. The carbon fibre plates are held together by the now familiar M2 bolts and M2 nuts. This methodology actually produces a very solid bearing holder which is then bolted through another carbon fibre plate which is sandwiched in between the side frames. In practice these bearing holders work exceptionally well in holding the main shaft rigidly in place. The plates the bearing holders are bolted to also contain the servo mounting points.

 

The same methodology is used to create bearing holders for the front pulley that drives the tail belt. It was here that I experienced my first issues with running this particular carbon frame. It is worthwhile before I go into the detail pointing out that this issue is not a problem with the frame but rather a problem with the Align front pulley. The Align front pulley has an annoying habit of the bearings coming loose on the pulley shaft. On an Align frame this is not an issue as the bearings are entirely encased. On this particular carbon frame a bearing coming loose on the tail pulley shaft causes a significant problem. What happens is that the tail pulley is able to come out of its bearing holders and this results in two things. Firstly the tail pulley gear rubs on the main gear and is destroyed. Secondly if you are flying you lose control of the tail.

I discussed this particular problem at length with the designers of the frame. The question was whether the frame could cope better with this particular type of failure. The answer was that the frame could easily be changed to provide some protection against the front pulley lower bearing coming out of it's holder. The fix implemented was to just add another carbon plate to the bearing holder in order to make it deeper. This effectively makes it much harder for the tail pulley to come out of its bearing holder should one of its bearings come loose on the shaft.

By far the best fix to this problem is not to run an Align front pulley at all. The MicroHeli front pulley is a better design that guards against this type of failure. I therefore installed a MicroHeli front pulley but also upgraded the bearing holder with an extra plate. Since doing this I have had no issues whatsoever with the front pulley or the bearing holders.

 

One of the best features of this frame is that the servos are mounted in exactly the same fashion as the Heliup carbon frame. This gives you direct ccpm linkage to the swash plate but also the servo geometry is absolutely perfect. The result should be that this frame from a cyclic and collective point of view will be as precise as the Heliup frame. If this is the case then this will be a very competent performer.

The servos are mounted to the frame in exactly the same fashion as used to bolt the frame together. This design feature is prominent throughout this particular frame and I have to say it works very well.

Below are pictures of the servos mounted to the frame.

 

One thing worth noting from the picture above right is that this frame accommodates the new design of ccpm swashplate. The anti rotation guide for the swashplate can be mounted in front of or behind the swashplate. Effectively this means that you can use either type of ccpm swashplate and this frame will not force you to buy a particular style of ccpm swashplate. This is a good design feature.

To finish up I have included below a number of pictures of the frame with all of the electronics installed. This gives a good guide to how this frame fits together. It also gives some suggested positioning of the various components within this frame.

 

Build Summary

This frame came prebuilt and therefore I cannot comment particularly on how easy or not it is to build this frame. Certainly there are not a huge number of parts and the frame does fit together in a logical manner. What I can comment upon is the overall design and rigidity of this frame.

Let's start with the rigidity as this is fairly simple. This frame is as strong and rigid as any frame I have tested and therefore I don't feel there are any issues to be considered with regard to rigidity. Due to the lack of aluminium parts it is also extremely lightweight. This frame weighs an amazing 56 g. It is therefore the lightest frame I have tested.

The only area that I didn't feel was as competent for rigidity was the tail boom clamps as mentioned earlier in this review.

I should also mention at this point that this frame comes with the most comprehensive set of instructions I have seen for any frame. The instructions are detailed, accurate and provide insight and advice on building the frame. The frame instructions can be viewed or downloaded here.

Flight Summary

My favourite frame for flight characteristics has historically always been the Heliup carbon frame. The interesting element with regard to this frame is that it shares the same servo configuration. Therefore it should have the same impeccable flight manners as the Heliup carbon frame. I do however still prefer the tail boom clamps on the Heliup carbon frame as these provide such a solid mount point for the tail boom.

Initial flights at the field involved some trimming out and getting a feel for the new frame. One thing that is immediately apparent is the lightness of this frame. Pushing on into 3-D this lightweight characteristic can continually be felt in the flight response. The T-Rex definitely feels livelier and the machine as a whole less strained to perform the more demanding flight manoeuvres. However, this lightness also means that the machine is more affected by wind and tends to balloon more when hit by a gust of wind.

Overall and rather than repeating myself and rewriting the Heliup frame review I would say that this frame has exactly the same mannerisms as the Heliup frame and therefore comes highly recommended. However it also benefits from being lighter and therefore feels more spritely than the Heliup frame.

Final Thoughts

Pros: Unique but proven frame design, great price, low part count, open design allows easy access to all components, extremely lightweight, extremely rigid, excellent flight manners.

Cons: Tail boom clamp although functional does not hold the tail as rigidly as an equivalent aluminium mount.

When I originally saw this frame I was intrigued by the all carbon fibre construction. I was also somewhat sceptical that this construction methodology would work. The construction is certainly unique and has proven to work extremely well. The only area of the frame that I still have some reservations about is the tail boom clamps. Although I have not had issues with its capability to hold the tail in place the clamp is not as rigid or robust as an equivalent aluminium mount. Given the lightweight design ethos built into this frame I expected some compromise and this is the only one found. However, I do not wish to labour this point as the clamp has been mostly trouble-free. One thing I did notice was that the tail belt tension does need to be checked more often as the tail boom is managing over the course of several flights to move slightly. This could easily be remedied by putting some electrical tape around the tail boom where it fits into the clamps. This would give the clamp a better surface to bite onto and stop it from moving.

Overall I think this frame offers excellent value for money, superb design and impeccable flight manners. On top of this it is as light as you are going to find on the market. Therefore it comes highly recommended.

 

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