"Poland is Not Yet Lost" - Flight Testing PZL

 Monday April 22 brought "warm enough" and "calm enough" conditions for members Jim R. and Steve B. to do some flight testing.

Jim did well enough with his upgraded UMX Waco (3S instead of 2S power).  But when everything is set up at the factory and you can launch in SAFE mode it shouldn't be challenging for an experienced flier.

The scratchbuilt PZL P-11c was another story.  It took off easily enough, but the trim seemed ineffective.  After landing Jim figured out his transmitter didn't switch to "cross trim" when he thought it did, and he was putting in rudder trim instead of aileron.

The first landing was way too fast.  The plane didn't seem to want to slow down, and Jim forced it on well above stall speed.  The result was a nice somersault (first picture).

Jim fixed the trim settings, made sure there was no damage, then took off for the second flight.  All went well until time to land.  Even after a practice approach the plane just didn't want to slow down.  Here's what happened next:

This time the spinning prop bit the turf and ripped the whole power package out of the plane!  A slightly humbler Jim takes a bow:

It looked like the end of the day for the PZL, but all the breaks were clean; so Jim whipped out the medium CA glue and stuck the motor mount back together.  While the glue cured during lunch, Jim remembered the eCalc exercise he'd done on the PZL a couple months ago.  The model's CG was a bit forward of the recommended range, but he had figured nose heavy was safer than tail heavy...

"Hey, Steve!  Got any stick on weights?"

Flight #3 was made with two 1/2 oz stick on tire weights (lead free, available at Auto Zone) under the trailing edge of the stabs.  The plane seemed much happier with all trims neutral.  Nothing dangerous about stall and spin recovery, and it was much easier to slow down.

The third landing still ended up nosing over, but not a violent somersault.  This plane may always be tricky to land with the long gear legs and nose high stance - but the aft CG was definitely an improvement.

Jim got out his eCalc paperwork at home - and the new CG checked out right in the recommended range.

Use eCalc.  It works!