Wednesday, August 17, 2011

Test flying the Aeros Combat 13.5 GT

The report below was written in August 2011. Here's a more recent report.

I had been waiting for this for almost 6 months. And thanks to Matjaz, I finally had the opportunity to fly the Combat 13.5. The 13.5 is special because it has an extreme aspect ratio of 8.5. This means the wing is 8.5 times as wide as it is long. And aerodynamics tell you that wings with higher aspect ratios fly more efficiently. That's why sailplanes have such high aspect ratios (long, thin wings). But for us, hang gliders, it is not as easy as for sailplanes to have high aspect ratios, because we lose maneuverability and pitch stability. Aeros claims that the 13.5 is as maneuverable as their other glider and has high pitch stability as well. So, with the promised extra performance and the glider being more appropriate for my weight than my current 14.2 (aspect ratio 8), I had to try it :-)
I launched into very calm air and the glider immediately felt comfortable and at least as responsive as my 14.2. It was gliding dead straight and did 3 km with a 15.7 glide ratio at 54 km/h. Hard to say how accurate this is, but it felt good.
The first thermal I hit, was a very light one. It was a struggle to stay in the air, but I immediately was sure that the glider was going to do it for me. The handling was very, very similar to my 14.2, with the exception of a much sharper stall when I was pushing too much to fly as slow as possible. I also had to push it a little all the time as the glider was trimmed a little too fast for me.
After about an hour, the day turned on and Carl and I had a 3 hour flight with amazing views over the Tolmin area. It was the first time I got into the higher mountains and you saw the remains of WWI everywhere. Trenches, bunkers, gun platforms, … We visited the war museum a few days before and now I saw it all flying just above it.
We had a few rough thermals as well and I had a tough time in those. But, I'm all over the place in rough thermals with the 14.2. I think the 13.5 was more maneuverable.
The 13.5 remains a Combat though. It is not allowing me to fly as close to the terrain as I see other gliders do. The handling with full VG is very stiff, so you have to be careful flying close to the mountains in turbulent air. But, it must be said, it is definitely not worse than the 14.2. And achieving that with a higher aspect ratio is a great job.
The effect of the higher aspect ratio was demonstrated when I had a glide next to Carl on his Moyes Litespeed RS 3.5. There was a clear gliding advantage for the 13.5. Sadly my harness rocked up a little when we went full speed, which wasn't ideal for the glide. Still, I had the same glide as Carl then, but the Combat could definitely do better.
Of course I wanted to land it nicely (Matjaz was watching in the landing field) and the landing felt easier than with my 14.2. I think it was a textbook landing with a very nice flare. The higher wing loading helps a lot to achieve this flare as I'm a bit light on my 14.2 and it is definitely harder to make that one flare nicely. Last year, I had one landing on the smaller 13.2 and that flared very nicely as well.
So, the handling of the 13.5 was at least as good as on my 14.2 (I'm light on that one!) and the glide was probably better. I liked flying it very much.
Major kudos to Matjaz for letting me fly his glider!


  1. Thanks a lot, Jochen, for a detailed and comprehensible description. One more thing: Could you tell us what your hook-in weight is? That would help assessing your impressions. Thanks again, best regards
    Carsten Zülch

  2. Hey Carsten! My hook-in weight must be around 105-110 kg. That puts me on the heavy end for the 13.5 GT.

  3. I READ SOMEWHERE THAT Dustin needed another thermal to make it into goal.

  4. Dustin and I thought we were going to need one. But Dustin didn't. He got an excellent glide and made it in from 53 km out.