Rotortech 515 Carbon Blades

Over the last few months I have been testing several different types of blades from different manufacturers. This review is the first of several looking at the merits of different carbon blades and their flight characteristics when coupled with the Swift.

The blades in question for this review are the Rotortech 515 mm carbon blades. These are a full 3-D blade and quite a popular choice amongst Swift owners. These blades are 515 mm from the tip of the blade to the hole in the blade root. They are a full symmetrical section and therefore will provide the same performance inverted (as is normal for 3-D blades). The blades have a very nice finish to them and a very distinctive blade tip, described as "aeroflat".

The blades have a blade width of 48mm and a blade grip depth of 10mm. This means for The Swift you must fit the supplied blade spacers. Additionally, I had to drill the blade holes to be 4mm as they come supplied with just a 3mm hole. I prefer 4mm blade bolts as 3mm bolts tend to bend on this size of blade.

 

Construction

The blades are extremely nicely finished. The carbon weave pattern going right to the edge of the blades. All of the edges are nice and crisp with no roughness or untidy finishing. The blade section is really quite slim and they feel thin in comparison to other competitor blades. The blade tip comes to a flat edge which is almost as thin as the trailing edge of the blade.

As most people will know the key to a good blade is both longitudinal and chordwise stiffness. These blades are very stiff from a chordwise perspective. However, longitudinally they are not as stiff as other competitive blades. This is very much down to the thin aerofoil section of the blade. However, this is not to say that the blades aren't stiff, they just aren't as stiff as other carbon blades in this length that I have tried. The blades did not require any balancing and were very well matched (as one would expect from a quality blade).

In keeping with the thin aerofoil and tapered tips these blades are quite light and therefore I am expecting quite a fast cyclic response but a less powerful collective response. Also due to the lightness the autorotation performance may be impacted. So with those expectations in mind let's move onto the flight testing.

Flight Testing

Lifting off into the hover I was very pleased to see the blades tracking perfectly. Something I noticed immediately upon lift off was an increased cyclic response. Whilst it did not feel fidgety or unstable there was a distinct feeling that these blades would be very quick on response.

My previous experience of light blades on the Swift was some pitching up in forward flight and an unwillingness to fly straight and level without some elevator correction. I was very pleased not to have to deal with this on the Rotortech blades. Forward flight was predictable and smooth and did not require elevator input to keep things on track.

Moving into fast forward flight I experimented with some tight turns, stall turns and then follow this through into loops and rolls. These blades are incredibly quick, in fact I was starting to wonder if my small T-Rex could roll as fast as the Swift with these blades on it. Loops could be tightened up so much as to almost loop within a 2 m diameter. In fact the cyclic response was so fast that I could perform (easily) square loops and 90° pull-outs from diving manoeuvres. Certainly this element of these blades is very impressive and allows very fast transitions between 3-D moves.

As mentioned earlier these blades are not the stiffest I have run and so I was expecting some softness in the collective response. This was not apparent from the flight testing and tick tocs were quite crisp and performed with a reasonable level of collective power. This was quite surprising given that these blades are not as stiff as any of the other blades that I have run.

Lastly I wanted to check autorotation performance. Again I was surprised to find that autorotation performance appears to be unaffected by the lightness of the blades.

Conclusion

These blades are quite a surprising performer given that their stiffness is less than competing blades. I couldn't fault collective performance or indeed autorotation performance, although these blades did give slightly less hang time. My expectation was that these two things would not be as good as other blades I have tried and they proved me wrong.

Where these blades really excel is in their cyclic speed. They are incredibly fast to respond and very tight manoeuvres can be performed.

Overall I like these blades, whilst they do compromise very slightly on autorotation performance in every other way they perform very well. If you're looking for an out and out 3-D blade then these would suit you very nicely. However, if you are just getting into 3-D then I feel that their speed on the cyclic would be a disadvantage and a more stable blade with less cyclic performance would be preferable.