They wanted to achieve trimmed flight with the elevons close to neutral position, at best glide. Both the evo designs always required a little trim to get it right. Basically, they took the best characteristics of the EVO airfoils and attempted to merge them, and at the same time thickness was reduced for the alula-TREK and camber was adjusted lightly as getting closer to the wingtip. But this was a balance, since they did not want to affect the flight performance and style much. In the end these changes, in their opinion made the design better in flight too. Forward sweep angle was reduced slightly to reduce amount of noseweight, and the nose length was increased slightly for the same reason.
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They wanted to achieve trimmed flight with the elevons close to neutral position, at best glide. Both the evo designs always required a little trim to get it right. Basically, they took the best characteristics of the EVO airfoils and attempted to merge them, and at the same time thickness was reduced for the alula-TREK and camber was adjusted lightly as getting closer to the wingtip.
But this was a balance, since they did not want to affect the flight performance and style much. In the end these changes, in their opinion made the design better in flight too.
Forward sweep angle was reduced slightly to reduce amount of noseweight, and the nose length was increased slightly for the same reason.
The chord lengths are also a little different from root to tip than the EVO Elevon area has also been increased slightly, and the reduced hinge angle affects the flight and control slightly too. The nicely decorated carbox is now rectangular and make the storage of the Alula TREK easier, without constraint that could deform the wing after a while.
The two wings are finished with the carbon spar installed and also the control horn in place. Same for the interlocking system, which is light and very convenient, or the magnets. The plastic belly skid provide a nice reinforcement of the nose, and allows; like on the Libelle to have a canopy to easily access the radio.
The canopy is maintained in place by 2 strong magnets. The fin and the print on the "fuselage" make the fixation thighter so stronger. A pocket with accessories contains the control rods ready to use, the clevises same as the Libelle , the interlocking screws some velcro adhesive. Another pocket contains the stickers and transparent stickers In term of moulding quality, I found it much better, with no mark of injection nozzle, nice edges.
Details are better respected and the surface finish is also nicer. In oder to give you a better comparison, below are some picture showing side by side some details: Now, there is a canopy on the TREK: Here you can see the better moulding quality on the TREK the interlocking system is simpler, lilghter and more efficient on the TREK Below the junction between the wing and the fuselage with the smart lip that lock the wing in translation, excellent idea!
On the left, no remaining work! On the fuselage, this is also quite fast. If you have the recommended servo or the one sold in option by Dream Flight, then after installing the servo arm in place, at the neutral position, you just need to insert them in their servo print, route the wire throught the wing until the receiver location.
The front of the radio compartiment is moulded for a mAh, NimH, 4 cells battery. The battery receives some velcro, before to be place in the fuselage. The receiver, a 4 channels from FrSky D4R with 2 antennas is located behind the battery. I placed the 2 antennas toward the nose, on each side of the battery. Not included in the 30 minutes, the painting.
I used some paper tape for masking, and an orange acrylic spray to paint. I needed 5grs in the nose on the side of the battery to obtain the market CoG. Finished, my alula TREK weights gr. To obtain a better launch the Alula must be perfectly trimmed to not diverge and climb straight. In flight, what is immediatly noticeable is the natural speed which is high. At the field, it is better to let the Alula to fly. If you try to slow her down the sink ratio increases quickly.
In the air, she is demonstrative and indicates the lift or sink air very well. Of course she will not be as competitive as a HLG in this excercice, but she is more than good enough to enjoy it! Compared to the Libelle, she is easier to launch, has a higher cruise speed but sink ratio is a bit higher, so where the Libelle can come back to be hand catched, the Alula will miss it by few meters from the same distance.
It looks like she borrowed some ADN of the weasel as she is fast, agile, and like to play. The looping is easy, and nice, when it was nearly impossible with the EVO, looking most of the time as a "comma" if she had not enough speed and energy. The roll can be quick or slow depending of your settings. With 10mm of ailerons, the roll rate is fine, but is more confortable with 13mm as indicated in the user manual.
The Alula TREK penetrates well the wind, and with the small ballast compartiment where you can have 20gr metal to 30g lead of ballast, it is even better.
At the landing the wings have a tendancy to open rotate, so even if the magnet secure the wings well in flight you can add a bit of Blenderm tape underside on the junction to avoid this. They liked a lot and all said: "Wow!
Therefore she can be flown more often in various conditions from no wind and pure thermalling to light breeze with the same joy and same smile on your face. From my point of view, Dream flight succeeded to propose us a revisited Alula, reducing the assembly time, improving her flying capabilities to satisfy even more people. It is easy to guess that this alula TREK will be another best seller considering how big was the success of the previous version, and how much the new one is awaited!
ALULA PLANS PDF
I opted to use just a permanent marker for color to reduce weight. I used an Azarr microantenna, which I embedded in the LE of the wing prior to the glassing process. Best of luck to you and your project! Nice little glider, I think it would do very well at slope soaring. Weasel or Alula plans anybody? I also measured where the pushrods were going to be and bored a hole alulla the pod to allow the pushrods to exit. Gone are the days it seems, when you had to buy this direct from dream-flight in the USA though you still can of course and get your spare bits from there also.
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