Helitec 325mm Blades
| Reviewer | Ashley Davis |
|---|---|
| Review Date | 16th February 2007 |
| Manufacturer | Helitec |
| Model | 325mm T-Rex Blades |
| Unit Cost | $42.99 |
The following is a review of the Helitec 325mm Blades. My thanks to CopterFreak for supplying these blades for review.
First some technical specifications:
| Length | 325mm |
|---|---|
| Weight | |
| Chord | 40mm |
| Shape | Symetrical |
Fitted Blades 
Fitted Blades 
Fitted Blades 
Fitted Blades
Build Quality
These blades are very nicely finished in a two tone colouring. I was actually sent two sets of blades, the second set being of black and yellow colouring. There are various colour choices which can be seen on the copterfreak website. The blades do not have any rough edges and the general finish is very nice indeed. The blades have a reinforced blade root with a brass insert for the blade hole. These blades are of symmetrical profile and are distinctive due to their very wide blade chord. This should provide plenty of lift but also may make this blade more power hungry due to that extra lift. Also I don't expect that this blade will be blisteringly fast from a cyclic perspective duty that large chord. The blades themselves came nicely balanced and there were no issues with the blade centre of gravity. The blades lengthwise are nice and stiff and I'm expecting them to be accurate in-flight. Helitec rate these blades as a beginner / intermediate blade so all of the above seems to match with the manufacturers rating.
Flight Review
I swapped the previous incumbent blades off of my T-Rex and fitted the new blades. Lifting off into the hover it was apparent that some tracking adjustments would be necessary. One turn of a ball link later and we were in business. My head speed is set to around 3000 RPM and the hover was nice and stable with very little vibration or unwanted flight characteristics. First test would be some hard pitch climb outs to get a feel for how much power these blades would sap. As I had expected with such a large blade chord the power requirements were significantly more than the previous blades that I had removed. I could hear the motor straining but the lift being generated was actually quite impressive. However, I was now expecting a shorter flight time.
The next few minutes were spent generally cruising around and getting a feel for the blades in fast forward flight. There is no tendency to pitch up and the model tracked extremely well with very little input required from me to keep it on the rails. Having spent some time sorting out the tracking, hovering and now doing some general flying around I didn't feel that I really wanted to try 3-D on this particular pack. I wanted a fresh pack for that. Therefore I decided to do some fairly steady climbs and try some autorotations.
Typically the T-Rex is quite an exciting machine to autorotate. Causing me in previous flight tests to compare its autorotation performance to that of a brick tied to an anvil. However, once you get used to it autorotations are actually relatively easy to perform with the little T-Rex. Having gained around 50 feet of height I flicked in throttle hold and descended at full negative pitch into wind. Again the descent was very stable, no tendencies to try to dip or roll out of the approach. At about 10 feet I brought the pitch back in and was very pleasantly surprised to hear a significant head speed increase as the blades wound up. On the flare I was presented with my first ever small hover at the end of a micro helicopter autorotation. Clearly these blades have an outstanding autorotation capability. I got some of this on video and it can be viewed below.
Autorotation Video
After five or six autorotations just to prove that the first one wasn't a fluke I stopped and fitted a new pack. Now was the time to check out the 3-D performance on this blade. Rather than talk through the entire flight my repertoire for this flight was stall turns, loops, rolls, side on and tail down tic tocs, piro flips, backwards inverted approaches with flips and continuous tumbles. I also did some backwards hurricanes although strictly speaking this is just fast backwards flight rather than 3-D.
Having worked through all of these manoeuvres my mind was fairly set on who would most benefit from these particular blades. The cyclic performance on these blades is not particularly fast in comparison to something like the Hyperion diamond blades. This means that manoeuvres like tic tocs and tumbles cannot be executed quickly. The roll rate although not what I would term slow it is slow enough to make me feel that these blades are not particularly aimed at somebody looking to do aggressive 3-D. These blades are very stable, very predictable but just not aggressively quick. They have a lot of lift and it is reasonably easy to bog them down if you over pitch the blades. With all this in mind I believe these blades would be ideally suited to somebody learning 3-D as they are quite forgiving. This coupled with the slower cyclic response means that there is plenty of thinking time (relatively speaking) whilst trying out new manoeuvres. If you are looking to learn autorotations with your T-Rex then these blades are absolutely ideal. They have masses of lift at the end of in autorotation and it is possible (with some headwind) to even hover at the end for a second or so.
Blades
Fitted Blades 
Fitted Blades 
Fitted Blades
| Pros |
|---|
| Nice finish |
| High-quality |
| Balanced and no centre of gravity issues |
| Very stable and well-suited to learning 3-D |
| Superb autorotation performance |
| Cons |
|---|
| Not ideally suited to aggressive 3-D |
Conclusion
Overall these are nice quality, well finished and fairly rounded performance blade. They would suit somebody learning 3-D and I highly recommend them for learning to autorotate with the T-Rex. If you are already an accomplished 3-D flier then these are not the blades for you as the cyclic response is not really quick enough for more aggressive 3-D flying. This matches the manufacturers rating of this blade as beginner / intermediate. For aggressive 3D I would be looking towards a blade with a narrower blade chord which should return a faster cyclic response. Either that or the same blade characteristics but shorter in length. Helitec also do a 315mm blade which is their 'Advanced 3D blade' and I will be reviewing this shortly.
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