|No Gyros Required- Dream-Flight Alula-TREK (0 min 17 sec)|
|Dream-Flight Alula-TREK, Go Anywhere (3 min 6 sec)|
|Wing Area:||259 in2|
|Weight:||5.6-6.0 oz. (5.7 for mine)|
|Servos:||2 x 4.3 gram digital servos|
|Receiver:||Spektrum AR6110e 6 Channel|
I had the privilege of reviewing the earlier Alula-Evo here in RC Groups. I found it a delightful plane and fun as a hand toss at thermal sites and even more fun at the slope in light wind. I still have, fly and enjoy my Alula-Evo so I was delighted when I got a chance to review the new Alula-Trek. Some of the changes between the Evo and the Trek were obvious even to me. I noticed it was made of a different, denser foam with no molding marks to sand off and greater strength. The new nose is longer and the wing is a different shape in several ways including being thinner and with less up-turn at the wing tip. I also found the Alula-Trek easy to assemble. As I was finishing up this review I received an E-mail from George at Dream-Flight with the design goals and improvements for the Trek from the Evo. I thought sharing that information made for a good start to this review and so here they are.
"1) New airfoil: It's a secret recipe! ;) We took what learned from the Evo series and applied this to the new Trek series. We 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, we 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 is adjusted lightly as you get closer to the wingtip.
2) We finessed the shapes and the thicknesses of the parts to reduce the volume so that we could use a little more dense foam for added durability. But this was a balance, since we did not want to affect the flight performance and style much. In the end these changes, in my opinion made the design better in flight too.
3) Design: In addition to the airfoils, we made some slight changes to overall wing planform. Forward sweep angle was reduced slightly to reduce amount of nose weight, and nose length was increased slightly for the same reason. The chord lengths are also a little different from root to tip than the Evo... a little less area at the tips, and with less wingtip up-turn. Elevon area has been increased slightly, and the modified hinge affects the flight and control slightly too."
The now discontinued Alula-Evo was a might nice sailplane, especially for the slope. I remember my friends acting like kids the first chance they got to fly her and she has always been a joy for me to fly. I had to go out and fly her before flying the new Trek to be sure I found the Trek to be a better plane and the Trek definitely is better! However, overall they are small differences in flight. I found at my local thermal field the Trek like's to fly faster, penetrates the wind better had a better glide path than my Evo. She turns a little more smoothly with her elevons performing more smoothly. More on my flight impressions later in this review.
Alula-Trek Kit Contents
Flight Pack for the Alula-Trek
Unless you have this size and weight of servos and battery pack I STRONGLY encourage people to purchase this optional flight pack with the kit. The plane was designed to use these components and they fit the molded spaces for them and they allow for the plane to be easily balanced. I have dozens of servos available to me but I would always buy this flight pack for the Alula-Trek if I didn't have these in a matching size and weight. It just makes proper assembly and balance so easy to get right.
This kit is very well designed and much of the work for assembly was completed by the manufacturer. It comes with carbon fiber already installed behind the leading edge of the wing. The tubes that receive the wing rod came installed in the wings along with the securing clamps at the root of the wings. Magnets came installed in the wing, the fuselage and the canopy. The wing rod came installed in the fuselage and the elevon control horns came installed in the elevons. The plane is molded to fit the optional flight pack servos and battery so installing them is easy. Assembly time is quick!
The wing came nicely molded in left and right halves. There was carbon fiber already installed in the wing and the wing rod tube came already in the wing ready to receive the wing rod that came installed in the fuselage. My work on the wing required a metric ruler and a hobby knife with a new # 11 blade. Per the instructions I made 20mm cuts every 15 mm along the aileron foam hinge line with 20mm of intact foam hinge on each end. This was quick and easy to do. Next I bent the hinges 45 degrees up and down to loosen them up. The cuts had reduced the friction of moving the aileron.
Next per the instructions I installed the wing tip decals top and bottom for hand launching the Alula-Trek. Two wing tip decals were included and they were to be installed on the wing tip I would be holding in launching the Alula-Trek. Since I am right handed that means that they went on the left wing tip. The wing halves were now ready to attach to the fuselage.
This was fast and easy! I slide one wing side onto the wing rod on the appropriate side of the fuselage. I had the wings leading edge angled downward and then rotated it to fit against the fuselage. A magnet in the wing locked onto a magnet in the fuselage. With the wing fitting nice and snug against the fuselage I installed the wing joiner screw into the black wing clamp at the root of the wing. By screwing in the screw the clamp was tightened around the wing rod locking the wing in place. For added security they recommend wrapping a strip of 3M Blenderm tap around the wing/fuselage joint at the leading edge of the wing. I then repeated the process on the other wing half. I didn't initially install the tape as I didn't have any handy but as I will explain later I strongly recommend installing the tape!
I am using two Dream-Flight servos from the optional Flight Pack. Per the instructions I trimmed one of the arms off of each recommended connector and installed them as near to center as I could and pointing out to opposite sides. I installed them in their molded servo spots on the bottom of the center section. I next pushed the servo wire into the battery/receiver compartment via the provided cutouts for the wires and then pushed the servo wires into the slots molded for them while pulling excess wire into the battery/receiver compartment. I secured the servos in place with the supplied servo mounting decals. I trimmed these decals to not be on the balance bar points on the bottom of the wing The servos were installed.
Next I installed the battery pack from the optional flight pack. It is 4.8 volts at 300mAh and fits perfectly in the front of the molded battery/receiver compartment. I secured it in place with the Velcro supplied in the kit after trimming off a small section of the Velcro for the receiver. This Velcro is very thin and I recommend using the supplied material. With battery installed I bound my receiver to the transmitter. I then installed the short battery extension wire from the option flight pack into the battery channel on the receiver. I programmed the transmitter next before securing the receiver in place as having it loose made plugging and unplugging wires easier.
I am using my Spektrum DX9 transmitter and a little Spektrum AR6110e receiver with my Alula-Trek. The two servos plug into the aileron and elevator channels on the receiver and I am using the first Elevon option from the wing programming on my DX9. This gives me the elevator throw in the proper direction. On mine the aileron throw was initially the reverse of what was needed so I reversed the way the servos were plugged into the two channels on the receiver and the problem was solved. With the aileron movement now correct I went into the Sub Trim for those two channels and centered the servo arms individually for both servos.
With the receiver able to control the servos in the proper direction for Elevon control I applied the small pieces of Velcro I had cut off from the supplied strips to the receiver and to the molded space in the battery/radio compartment.
The instruction manual has the assembly of the control rods earlier than this but I did them my way, The clevises are made by folding them together. The control rod will fit between the two clevis sides. At the back end there is a pin that will fit through the elevon control horn and a hole on the other side of the clevis. The front of the clevis is held together by a supplied screw. I bent the clevis to the shape it was supposed to be and started the screw into one side of the clevis. I took the control rod and put it through the servo control arm and had it lined up with the aileron control horn. I fit the clevis pin through the top hole in the elevon control horn and the hole in the other side of the clevis and I had the open half of the clevis facing down. I moved the control rod up into the clevis and above the screw area and pinched the clevis together with one hand with the control rod in the proper position. Using a small screwdriver I screwed the clevis screw into the other side of the clevis. Making sure the elevon was in the proper centered position and having previous made sure the servo arm was properly centered I tightened the screw and the clevis and control rod were properly installed. I repeated the process on the other side. Trust me when I say I found these clevises fun to install and they have worked great!
The vertical stabilizer has molded bars top and bottom that slide into a slot on the back of the wing. There are molded spaces on each side of this slot into which molded bumps on the vertical stabilizer fit to give a good tight fit, locking the stabilizer into position with friction with no need for glue or tape. If it is removed frequently and becomes loose over time it can be secured in place with tape.
For Completion I added a few of the included decals to the top of the wing and protruding center section. I went to page 13 of the manual and programmed in the high and low dual rates. I followed their instructions and marked a piece of tape at 3mm, 5mm, 10mm and 13mm up and down. This let me program the elevator low rates at 3mm and high rates at 5mm. This required a large reduction of the travel for elevator that was there initially. For ailerons it was 10mm of movement for low rates and 13mm of movement for high rates. With the DX9 this programming was easy to do and I selected two switches to control the dual rates. You may question the low throw for the elevator but that proved to be all the movement that was needed in the flight testing portion of this review.
The plane is suppose to balance on the two balance bars near the front of the servos. Mine was initially a little tail heavy. Possibly because my receiver is so lite. I added a dime next to the battery and she balanced perfectly on the balance bars.
Dream-Flight includes some decals that can be used on the Alula-Trek if so desired. Since I used only one decal on my Alula-Evo I decided to use three on my new Alula-Trek.
For breezy conditions on the slope they have a small ballast box in the back of the battery/receiver compartment just behind the carbon spar wing rod. Dream-Flight sells some optional steel weights (part DFAA002) and the compartment fits exactly four pieces of this steel ballast per the manual. Each piece weighs 5 grams. They recommend a small tape tab on the ballast to be able to easily remove the ballast.
The plane has elevon controls. This means the control surfaces on the back of the wing serve as both ailerons and elevator. I found it extremely helpful to limit the travel of the elevator to the recommended throws in the dual rate setups given above. This meant greatly reducing the movement for the elevator. Adjusting the aileron throw was also helpful but not nearly as important as limiting the elevator movement to the recommended amount.
There are two ways to fly the Alula-Trek: Thermal or slope. At a thermal site the Alula is launched with the pilot turning and flinging the Alula-Trek forward and slightly up in what is called a discus launch. I hold the outer left wing tip between my thumb and index finger with the bottom of the thumb and the side of the index finger clamped onto the Alula-Trek as I spin and throw the plane hard and high into the air. When the energy from the hand launch has been lost I level off the Alula-Trek and go in search of a thermal to lift the Alula-Trek up higher. Her flying speed is higher then I initially expected and definitely higher than my Evo. This gives her a better glide ratio as well as better penetration. DON'T try to slow down her natural glide rate as it negatively impacts how she performs including increasing her sink rate. With no motor, if lift is not found the Alula-Trek glides back down to earth where I launch again and search for lift. The good news is the Alula-Trek is pretty responsive to lift and goes a bit nose down yet climbing when in lift. Spotting this thermal tell is critical to flying any sailplane. The Alula gives a recognizable tell to help me spot when she is in lift. Hitting the side of a thermal she does get pushed away so I have to turn her about 270 degrees and head into the thermal.
Once in the thermal I start circling and try to center the Alula-Trek in the thermal and ride the thermal up. The thermals are usually drifting with a breeze so it is important to allow for that drift to stay in the thermal. When I am successful I usually have to leave the thermal before the Alula-Trek goes too high for me to see her. Often after climbing for awhile I simply loose the thermal and the Alula-Trek starts gliding down. Then the search for the next thermal begins or I enjoy doing some aerobatics.
Slope flying also requires a hand launch but here it is forward off of the hill and into the wind. It is usually a softer launch by me as I am depending on the breeze keeping the Alula-Trek aloft. Flying in the wind lift I stay in front of the slope and can use the wind to climb or I can dive down through the wind to get speed for aerobatics. I can fly right in front of my face for as long as I want or as long as the battery lasts. With small stick movements I can fly the Alula-Trek very smoothly and she looks very much like a bird taking advantage of the wind to soar and hunt along the ridge of the hill. She flies very nicely in just a five mile per hour breeze or even a little less so long as it is steady. If the breeze picks up I have to hold in more down elevator or I can land and add ballast in the ballast box discussed above. The added weight should allow her to better penetrate the wind and flight to remain more level as long as the wind doesn't get too strong. I say "should" as the wind has been marginal so far on my trips to the slope for this review. The Trek flies better than the Evo in a light breeze and with her ballast box I think she will fly better in stronger wind as well but I haven't gotten a chance to test that assumption yet.
Whether flying at a thermal or slope site all flight is controlled by the right stick alone as I use mode 2 on my transmitter. I can go between low rate with reduced elevon movement and high rates by the flick of two switches. High rates are used by me for the more aerobatic flying discussed below.
My Alulas Side by Side
I found hand flying in the early morning at the local park before work to be the most accurate way to test the handling and flight characteristics. I have found that I can best tell how my sailplanes are handling when there is no wind or breeze nor any lift as the sun has not started to heat things up. So while I have flow the Trek and the Evo in various conditions it was in these early morning conditions that I confirmed to myself that the Trek flies faster, has a better glide ratio and from the same altitude I could generally get a slightly longer flight with the Trek over the Evo. It was in these conditions that the turns were easily observed and that the handling was improved with the Trek. The improved glide ratio with the Trek was easily the most noticeable difference to me and again it is not a huge difference but I saw it as did an old friend who joined me early one morning. Since the Evo has been discontinued this testing by me is really moot especially since the Alulas are really more for fun flying then competition. However, I did enjoy comparing them and was happy to see enough difference to conclude that the Trek really is the better plane.
As discussed above all flights require a hand toss to start. A hard toss while I am slightly turning is used at thermal sites and normally a softer toss is used by me at at slope sites. Launches are easy to perform when she is in proper balance and trim. Flights can end by catching the Alula-Trek or by sliding her to a stop on grass.
In thermal flight the improved glide path and her slightly smoother handling seemed to let me get more climb from a thermal and longer duration out of the thermal. I have an average throwing arm now so I don't get the hand launches I got ten years ago but I was able to get some nice launches and caught multiple thermals on a couple of different days while doing this review. Good launches with visible tells when encountering thermals and climbing in thermals is Special Flight Performance for me. At altitude she can perform loops and rolls and that is a very fun and nice quick way to bring her down.
Aerobatics are perhaps best enjoyed at the slope where despite performing loops and rolls the wind supplies the lift to stay aloft and keep doing those aerobatics over and over. Mixing aerobatics with flight that generally looks very much like a bird riding the wind and hunting the ridge for food gives me a lot of enjoyment. Her ability to fly in light lift allows for a lot of pleasure even on days where flying aerobatic lead sleds is the desired goal at the slope and we end up waiting for stronger lift.
I went to Los Banos the weekend of South Bay Soaring Societies Aerotow. It was great to see some old friends and meet some people that are RC Group members. Several of them own the Evo and they were interested in seeing the Trek up close and while flying. Unfortunately, the wind was very weak and kept stopping while I was there and we had to land several times after very short flights by my friends Brian and Charles. However, Brian was able to get in enough air time for me to shoot the stills and Charles flew while I shot the video clips during three relatively short bursts of flight. There was even a crowd of interested pilots watching. Brian had a hard landing after I asked him to come closer and the wind died. A wing came loose on that landing but was easily placed back in place and re-secured with the use of a screwdriver. At that time I wrapped some tape around the wing joint line in front top and bottom. A picture of the temporary damage is shown below. I recommend pilots install the tape per the instructions while doing the initial assembly. I wish I had. DOOH! Oh well, no harm, no foul!
On a different afternoon I had a chance to go to a hill closer to Stockton and got in an uninterrupted hour plus of flying time on the slope. The wind was not strong but at least it wasn't dieing. Here I was able by diving to get up the speed needed to do loops and rolls. She does a nice loop that can be done large or small. The Evo is much harder to loop properly. In light wind the rolls were done best heading straight into the wind. In stronger wind Both the Trek and the Evo can do rolls flying across the slope but again the Trek does then sharper in 8 mph wind. The Trek made better rolls straight into the wind of about 4-5 mph. The Trek's smoother foam definitely made her the prettier one to watch. I would have liked it if the wind had built so I could test out the ballast box but when I landed to add some ballast the wind actually started to lessen from the approximate 8 mph back down to about 4.
In my previous review of the Alula-Evo I gave the recommendation below and I stand by that recommendation for the Alula-Trek as there are easier/better planes for beginners to fly.
"Some of my students in the past found elevons a difficult way to start. The Alula can be flown by a beginner who understands small movements with elevons are all that is needed for control. I think she will be enjoyed more by the pilot who knows how to fly and is looking for a fun plane to hand toss on a nice day at the thermal field or when flying at the slope. But a beginner with a good instructor or good flight simulator could start with the Alula, but it would not be my first choice for a beginner."
The Alula-Trek was flown at the Los Banos slope in very light wind conditions as described above.
|Dream-Flight's Alula-Trek at The Slope (4 min 59 sec)|
May 23, 2015, Sunset State Beach near Watsonville, CA: winds 14-18 mph while flying and overcast. Ballast added was 3/4s of an ounce but it was all that was needed.
|The Alula-Trek in Wind at Sunset State Beach (5 min 3 sec)|
The wings attached with the built in magnets and one screw per side. Her new design is very well thought out and executed. The optional Flight Pack servos and battery pack fit perfectly. No glue or sanding was required for the Alula-Trek. The clevises and control rods are different and I found them fun to assemble and install. Total assembly time with radio installation and programming took me about an hour. After she was assembled than the real fun began. Flying!
I really enjoyed assembling my new Alula-Trek! It was obvious that she was much prettier close up with the denser foam and no foam molding marks. But her true beauty is how she flies and in my test flying at my local park she proved to fly faster, have less drag and turns were actually and these combined to give the Trek a better glide ratio. The improvements were significant in my opinion but a really skilled hand toss pilot could still probably beat me with him flying my Evo and me my Trek but I would pick the Trek for any competition with Alulas or for fun flying.
Dream-Flight set out to improve what I though was already a very good plane that was fun to fly and I believe they succeeded wonderfully! They hit their target goals stated at the start of this review and the Alula-Trek is both a better performing and prettier sailplane. As stated previously, I noticed a naturally faster flying speed with less drag. I noticed an improved glide path as well as smoother turning ability which further reduced drag. With sailplanes small improvements can pay big dividends in handling and flying time. These were more than just small improvements in my opinion.
Despite what appears to be a very close resemblance between the Evo and the Trek they are really very different in design, assembly and flight characteristics. The Trek's new secret airfoil is superior to the Evo's. Despite using a heavier denser foam the Trek uses less foam, is stronger, lighter and flies faster. She is better balanced and easier to launch at the thermal field or at the slope. The radio/battery compartment is now easy to access so the battery can quickly be changed for extended flying time. I compliment Dream-Flight on their excellent new plane the Alula-Trek.
I have trial fit a Spektrum 6115 top pin receiver into my Alula-Trek and the top fits without any pressure against it and no cutting of the foam so it should be good to go. Several requests for my program for DX9. I must have done it late as night as I used airplane not sailplane as my model type. Here is what I found when I checked my transmitter. Mike
Model Type: Airplane
Aircraft Type: Elevon
Aileron 100% high and low
Elevator: 35% high and 22% low
I tried playing around with programming and could only select elevons in airplane mode so believe you did it the only way possible.
Thanks for the other DX9 programming. I'll have to look at the differential programming. I thought it was set up as a percentage but maybe that is on a two aileron setup on a normal tail configuration?
We have found it to have improved (closer to neutral feeling) inverted than the EVO....but pitching/looping maneuvers are where the energy really builds and you can carve some very cool high-energy close in stuff. Small adjustments to the CG really help dial it in for your taste. Simply move the battery a hair at a time on the included super thin yet sticky velcro till it feels good. Being able to adjust battery position for fine tuning CG is one of the many design upgrades of the Alula-TREK versus the older EVO.
Last edited by george@dream-flight; Jun 08, 2015 at 12:32 PM.
She is superior to the Evo for flat land thermaling! She has less drag and better penetration but still gives tells when thermals are encountered and responds well to lift so you should be able to take advantage of the thermals you encounter. Mike