Scale Soaring UK

Yesterday me and a friend went sloping with a recently bought European "professionally " built Petrel to 3.5 scale of 5m span. I was offered a fly and on first view it looked well built and finished. However it was flying with quite abit of right aileron trim. So I started to explore the flight envelope. The dive test and stick free stability were fine. The control harmony was good. Then stalling and tight turns showed a fairly marked right wing drop followed by a full departure and spin. We then did a rigging alignment check and discovered that the right wing incidence was a couple of degrees or so more than the left ( at the wing root).
To solve the problem would require extensive surgery around the large fuselage root fairing, having moved the incidence pin and reblending the fairing from leading to trailing edge. This seems alot of work with refinishing and painting the fuselage. The question is why doesn't this model glider manufacturer take the trouble to rig check his build before finishing the fuselage and wing root fairing ? The error was very easy to see if you took the trouble to view from 10m behind the glider. This does not see to be a "professionally " built job to me. Regards John.

Exactly.....without a name it’s just a “story”!

Patience Gentlemen, there is some serious negotiations going on here ! For those who can't work it out it will be revealed in the fullness of time.

I suspect that top end 3D CAD drawing, coupled with laser cut parts, might lead to the conclusion that everything should be a perfect fit. In my old-fashioned 2D world, I spend an inordinate amount of time matching one wing's incidence to the other. To do this, I always rely on the MK1 eyeball...

The MK1 eyeball................when you've finished with the techy incidence tools the final ultra hi-tech eyeball check is foolproof.

If it is the one I think it is, it is not laser cut! CNC'd with router. Is there any difference in the end result?

Less smoke????



BC

Chris
The model in question is mine and you are correct, cut with a CNC router. This is the second ARF I have acquired from this north central European manufacturer of sailplanes that can be purchased in kit, ARC or ARF form. The first also had rigging issues but to a lesser extent which I corrected as best as possible without surgery and sold the model on.

But getting back to the Petrel. In addition to the wing incidence I had to correct the tail alignment and fine cracks are developing beneath the Oratex covering on the fuz around the nose and tail which I think is filler cracking. It is a real shame. The construction of the individual airframe components is good in terms of accuracy and craftmanship and the finishing not bad at all (yes there were the usual cosmetics to sort out including paint runs). But the rigging is dreadful.

As I'm still in full time employment and travel extensively for work building a vintage glider is not feasible for a few more years so I generally fly modern glass gliders. And while I would like another larger vintage glider in addition to the Petrel ARF options are limited. I will certain not go with another product from this particular company (the Petrel supplier).

Perhaps I should have searched for CW Petrel that someone would have been prepared to sell.

Regards

Neil

Okay, I am sure most people would have worked out the manufacturer of this Petrel. I am incredulous that Old Gliders of Poland would send this glider out without even a basic rig check. Regards John.

Good job the PWS 101 I aquired was one built from a kit of parts then.
Thanks for the heads up, as it is my winter project to cover and paint.
I will put a rigging angles check as the first job, while it is still relatively easy to fix any problems.

John M

Its been a while since the last communication regarding this topic but the matter has moved on. Ultimately it was established that one wing panel had approximately 2.5 degrees of wash-in while the other 2.5 degrees of wash-out (as intended). The wings are jig built so this is difficult to understand but Old Gliders did acknowledged the problem. With my agreement John McNamara (Jettstream) did try to correct the wing but to no avail. So in response Old Gliders decided to build me a new wing. In their defence Old Gliders did initially want the entire airframe returned which I didn't want to do. Anyway the fuselage was sent to Old Gliders for the new wing to be made.

The new wing was made and the panels and fuselage sent back to me however the airframe arrived damaged. While I can't prove it I'm 100% sure a certain warehouse located in Hams Hall felt the package needed ventilating and stuck the forks of a truck through the box. So not only were both wing panels damaged so was the fuselage. Although the damage was not major and could be repaired Old Gliders have decided to draw a line under this particular airframe and either build me a brand new airframe or refund me.

At times it would have been very easy to "throw the rattle out of the pram" and simply demand my money back and never consider an Old Gliders product again. Some may say you should build you own which is fine if you have time and space. And I may do so when I retire. But now the best solution for me is either an ARF or a used model but acquiring a high quality used model for sale in excellent condition does not appear to be easy.

The Petrel is a beautiful sailplane and the Old Gliders Petrel flew well even with the defect. The airframe seems well engineered and the quality of construction very good. Yes I had a defective wing panel but according to John McNamara who has distributed many Old Gliders airframes, I'm an isolated case. So I have decided to have a new airframe built. I'm confident I will get a good model but I will check the wash-out. Only concern is getting it delivered without damage.

Neil T