Hi everyone -
I had a couple of speedsters out at the field yesterday to have some 4S fun. I had already flown the F15 MK2 with a 4S battery about 6 times, but had not gotten video of it. I had also never flown the T50 V1 on 4S either, so I was excited to do that. It was a bit windy at the field, wind was about 10-15 mph, so I was sweating a bit flying the T50 in the wind as I was unsure of it's wind stability. Anyway after it launched out of my hand smoothly on three consecutive flights, I reminded myself of one of the first rules of aerodynamics, launching it into the wind causes airflow to go over the wings, increased airflow causes increased lift and normally the more lift, the more stability...so all was good... :)
I flew a couple warmup flights on the T50 on 3S before trying it on 4S and was actually amazed at how stable this plane was in the wind as long as the speed stayed up. I expected to be tossed all over the place and there were a few tricky moments, but overall I was very impressed. Turns did need a little more speed and room as I found if I tried to turn too tightly with that large area of wing and elevons making for a lot of surface area, a 45 degree bank could become a 90 degree bank very quickly and I would have to correct back the other way (not something I want to do if I am getting too close to the trees).
Additionally, I have found especially when turning from a headwind to a tailwind there is a small part of the turn where the only air flowing over the elevons is from prop wash until the plane levels out and gets going downwind with some speed again, so if I pull too hard on the elevator, I can get thrust vectoring stalls where the elevons act a little bit like speed brakes. Not what a I want when I am in a turn...my poor old reflexes sometimes aren't what they once were... :/
So onto the fun stuff...the 4S runs... :) I had to take into consideration the wind today, but I am pretty confident that I had four good runs of 96/95/93 and 91 mph slowing down a bit as the battery lost it's "mojo". The wind played a few tricks at high speed, I saw a bit of torque roll occasionally and once in awhile a bit of zooming, so I am excited to try it out when it is dead calm. I will say that other than the wind, it is rock solid at high speed, in fact the faster it goes, the more stable it is I have found.
So it is dead equal to the F15 MK2 for 4S speed and about 6 mph slower than my fast Mig.
So of course I start asking myself why a smaller plane that weighs 1.5 oz less than the Mig and 3 oz less than the F15 not go the fastest? Well, to be quite honest, when I see some foam and glue going that fast, 6 mph is negligible for my 52 yr old eyes to detect, my heart still pounds and my smile is just as big at 96 mph as it is at 102... :)
So as I said before in a previous post about the T50 and top speed on 3S, I think I am pushing up against a bit of a drag barrier somewhere. At half throttle, I would say no doubt the T50 is faster and quicker than the F15 and Mig 29 with the same power setup and it accelerates like mad up to a certain point. When I look at the picture above, I see a lot of angled leading edge on the T50 V1. The F15 has that blunt front of the intake, then other than a very subtle curve, nothing until the swept wing.
Maybe the top engine piece that I am sure provides a lot of stability for the T50 may also cause a bit of drag? There is surface area there although as sleek and tapered as I could get it, it could be causing some drag. Could it be angled vertical stabs versus perpendicular causing a bit of extra drag? Interesting stuff to think about but as I said the numbers don't mean that much until after the fact...96 or 102 mph it is still pretty darn fast and exciting for some foam and glue to go that fast when I am standing at the field with my transmitter in hand!
After I posted this on the RC Powers website, Scott Lott (the designer of this plane) told me that he thought most of my drag problem was caused by the large Kf airfoil. In testing he did in the sim for the V3 lineup of RC Powers planes, some planes can sometimes double the frontal surface of the plane with large Kfs. I believe that the Kf does provide considerable stability to this plane, so for the sake of a few more miles per hour, I will keep the large airfoil...:)
Anyway, this little V1 plane continues to amaze me. I am starting to think about building another F22 V1 to compare, but several other projects to get to before then... :)
Cheers,
Scott
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