Flight report: T-Rex Electric ARC. Well I was getting close to being able to put in a full flight report but since the weather is starting to look limiting I'll share what we have observed. I have been trimming it out with Rick Sawicki, Frank Carslisle, Dennis, Arch, and Big Art Adamisin. Started flying with 4S 3000 mah 20 S packs but after several sessions I was not getting the reserve power I wanted. The airframe is quite draggy and lets admit it it is not a .35 size airplane either, it is a .60 size plane. But since Rick's and my research base is the 2826/12 on 4 cells that is where I started. Flying on 63 ft lines line tension has been consistantly good even though I was flying in the 5.5- 5.6 sec lap range with the 3000 mah pack with an APC 12X6EP. Switching to 3700 mah 4S 20C pack let me get the into the low 9K range it looked like i needed but I did hot have enough headroom on 4 cell system for my satisfaction.
As a result I switched to 5S 3000 mah 20C packs today. Now I have a lot more range of rpm to play with. I thought going in I would wind up with 5S power and you will note that is what is pictured in the build thread. This gives me more options prop wise. It turns out to do 5.3 sec laps on 63 ft requires about 9300 rpm on 63 ft wires. I have decided though to go to 66 ft. The plane flies in the space of the 63 ft lines but turning 9600 rpm on 5S I am really being pretty gentle on the system and will gain the space to open up the maneuvers even more. I think the size of the plane just makes a 5S system more doable and there is little weight difference. All up launch weight with battery is 65.3 oz with the 5S system. But I think I'll gladly trade the small weight gain of the 5S pack (which is considerably shorter than the 4S and only 2.3 oz heavier) for the flexibility and the greater amount of headroom reserve in the system. It will also let me experiment with the low pitch prop option as I go down the road and see how I like that. Line tension in all areas in excellent with the 5S stystem.
Handling wise the plane is very good. It grooves extremely well. It requires no concentration to fly dead level with zero bobbles. Best plane I have ever flown in this regard. Corners are nice. They not only present well, but there is zero overshoot. The plane comes out very flat and very predictably. Rounds are very smooth both inside and outside and it is very easy to produce even sized loops each way. The airplane does not require constant steering through rounds. It just does them predictably. Transitions do not move very much. This gives a very precise impression from the handle. Arch and I both noted that the electric Stregas we both fly (he on a 6 S low pitch prop system, myself on 5S 6.5 inch pitch system) while they fly and turn at the 80 ounce plus weights on electric power with the flap mods we have done, they are not predictable about "where" they are going to turn. They seem to skid a good distance after control input before the maneuver happens. The result is that you guess as to where the intersections will wind up. It requires a lot of work to overlay maneuvers without having them travel. The T-Rex does not do this at all. It does the maneuver very much where you do it (hmmmm, 20 ounces less weight might have something to do with that!). This creates intersections that are much more easily consistent with where you think you are doing them and laying intersections and any of the other repeated maneuvers right over themselves is a much easier task. The impression you get flying it is thus that it is very precise in doing what you want and it takes very little work to do it.
I wound up with 1.5 oz in the weight box. This was not determined by any hinging though. I flew it with up to 2 ounces in the box. The airplane never hinged in a corner nor produced any hint at a stall or having any kind of a weight issue. Once we got the wings closely adjusted with the Bob McDonald flap adjuster and found it would not come out even upright and inverted we simply removed weight from the box until it did.
I will post the battery usage numbers tomorrow after I get the recharge cycles done.
In summation I think the plane is an excellent flier. Big Art feels that I certainly have a very competitive plane. Frank Carlisle who has been my coach for years feels like my flying has taken an immediate quantum leap with the airplane. It is certainly a plane that gives you confidence as you fly it. It presents very well in the air. With the abundance of power I have with the axi 2826/12 on 5S packs (btw, neither motor nor pack made it to 90 degrees today, 50 degree day) I have a lot of flexibility. I think going to 66 ft lines will be a very good benefit of this flexibility. Being able to dial in the rpm precisely is another advantage as it makes it very easy to get precisely the lap time you want flight after flight.
I want to really thank Brad Walker for his considerable time and effort in creating a truly high level competition plane at such a low weigt and to John Brodak for the work and patience to see it come to fruition. I think advanced and expert fliers will find it is a very nice option in the range of aircraft we can select to enter competition with. I have posted a detailed build thread on the electric forum.
bob branch
Topic: T-Rex flight report (Read 1543 times)
