Saturday, June 16, 2007

Grob 103 Rear Seat

Today I helped T and an instructor work on the instruments in the Grob 103. It needed a test flight to see if they worked correctly, so the CFI and I took it up together. That was a good opportunity to get a signoff to fly the Grob from the rear seat. You may wonder why that needs a signoff... well, there are a number of differences between flying front and rear seat (in any glider):
  • First of all, the forward view is different, sometimes rather restricted. In this case, it's not too bad. The front passenger's head blocks the view directly forward, which makes it hard to see the towplane. CFI suggested I tow just a little to one side of center, which helps quite a bit. Actually, with the big canopy, the view is not as restricted as from the rear seat of the Blanik L13. And in the Blanik, you get quite a lot of reflections on the inside of the canopy. In the Grob, that did not seem to be nearly as noticeable. The view down and forward was just good - no problem for landing.
  • The view down and behind is blocked by the wing. But not a problem. My view of the runway during the downwind and turn to base were fine.
  • The posture is quite reclined, depending on how you set up the cushions. CFI thinks it's uncomfortable. I thought it was fine.

Anyway, it's different enough that it's worth having an instructional flight. Mine went fine. So now if I want to take a passenger in the Grob, they can sit in front and get the best view.

I mentioned the instruments... the rear variometer turned out to be bad, or hooked up wrong, or something. Its indication was useless. So for most of the flight I was going by feel or asking CFI what his vario said. Quite a pain, and I would not fly a passenger with it bad. Hopefully we'll get it fixed or replaced soon. And that was the purpose of that flight, right?

The other thing was that the airspeed indicators were off a bit. The front reads about 5kt less than the back. CFI seemed to think I was flying too slow (i.e. thought his was correct) so I went by his. But on landing that meant mine indicate 60kt instead of the target 55kt, and the results were consistent with 60kt: longer float and rollout. We actually stopped past the end of the box a bit. So I conclude that the rear ASI is correct, and the front under-reports.

It was about 10:30 am, and there was a little bit of weak, scattered lift which we took turns working. I realized that I have not been a passenger in a glider for about 4 years. Ever since I started taking lessons, I've done all the flying. It was strange just doing nothing. And at times slightly disorienting, without the tactile and kinesthetic feedback of flying the plane, especially when I was looking inside the cockpit (reading instruments for our testing). A good reminder of what passengers feel! We ended up with just a 27-minute flight.

Later in the day I flew the PW-5, taking off at 15:12. Although there had been pretty good lift until then, marked by strong dust devils, by the time I got up the wind was blowing out the lift and no dust devils were visible anymore. I found some zero sink and scraped out a 25-minute flight. On the plus side, we were having a contest, which included a spot landing event. On the rollout after landing, you have to see how close you can come to a cone without going past. I stopped 10.5 inches from the cone. As far as I know, that was second place... the mark to beat was 8 inches. I'll have to wait to find out the results.


AIG said...


I just found your blog and am a new student.

any suggestions re: good soaring simulator software?

Roger said...

I first used Sailors of the Sky and later Condor. A few comments are at

I have not used either one much lately, but as I recall I preferred Condor. The scenery in SOTS was pretty sparse and did not look much like reality... when I flew for real at Minden it looked nothing like the sim.

I used SOTS for practicing rope breaks early on. It was very helpful for repeatedly practicing the turn to get back to the field. But note the problem with rudder linkage that I mention in the other article... I kept spinning the glider accidentally, which I never did in real life.

A few months ago I used Condor to practice winch launches in advance. Also very helpful.

Neither one is very helpful for practicing the final stage of landing: the touchdown. So many visual, auditory, and kinesthetic cues are missing, it's really hard to judge your altitude just above the ground.

SOTS includes a Blanik L13 (the trainer I used), Condor does not (or at least it didn't when I downloaded it).

I hope you find my blog helpful. Follow the links in the right-side pane to find my earlier posts - they'll relate more to your early training. And welcome to soaring!

AIG said...

Thanks Roger.

This might be one of many replies that I tried to send. Feel free to edit/delete as you see fit.

I'm now up to date on your posts. You write very well, many others certainly appreciate your efforts.

You had posted something about an excel bases thermal table. Could you send me a copy at:

many thanks in advance