The Parkzone F-27 Stryker is an amazing airplane, especially at the price.

The inherent stability and good low-speed manners of this model break the traditional idea that fast pushers need to behave like lawn darts.

I build my first Stryker from parts last year, employing the E-Flite Six 2700kv motor and 3s high-capacity Rhino batteries.  With a 6×4, we were seeing 85-90mph reliably in radar passes, and the model handled great.

I started reading about the EFL Six, and learned that you can push a lot more than the recommended max of 42 amps.  I decided to order up some 4S Rhino batteries, and build a new Stryker.  I used an Align 450 K10175A heat sink, and decided to try one of the new Turnigy 85A ESC’s that have a built-in heatsink.  I also installed a motor temp probe for the Eagletree logger.

The first flight was uneventful, until I really started pushing up the speeds.  We saw a couple of 85+ mph passes, and whenever I started flying faster than that, I started noticing some serious problems steering the aircraft.   We decided that I was going to need to beef up the airframe and the elevons in specific before flying it any more.

I beefed up the structure with carbon fiber rod, and day-glo duct tape.  I applied CF tape and thinned epoxy to the underside of the elevons, which helped quite a bit.

At this point I also got a little reckless, and installed a new prop.  I had been running with a 6×4, and decided to put a 6×5.5 on there without thinking about how much of an increase that was. 

….  and it proved to be too much.

The model flew much better with the stiffer airframe, and spent the first part of the flight just getting used to it.  Finally, I decided to ‘give it the berries’, and see how we fared.

I wasn’t sure, but I thought I saw a little smoke trail on that climb.   I did a nice long power off glide, pretty much assuming that the motor was fried.  When I throttled up again, I was astonished to hear the motor spin up.  I decided that I must have been seeing things, and did another pass.

This time the smoke trail was unmistakable.   I spun it around, power off, and landed.   The motor was crispy critters, you could smell it a mile away and it was actually melting the plastic motor mount. 

In reviewing the data, it looks like I tried to push 96 amps through the motor, and the sky-writing was predictable at that current.

Eagletree graph, illustrating abuse

 I really should have been more cautious, we live and learn.

I got one of Custom RC’sStryker modular motor mounts, and this is a really nice looking part.  It is available with a 28-30mm head, a 36mm head and also a special 36mm unit designed for Mega motors.   I plan to use one of Hobbycity’s 36mm inrunners, although getting the model to CG will probably be a challenge.

More news as it becomes available,

- Eli

UPDATE 3/22/2010 -

First, a word on Custom RC.  Not only was the Stryker motor mount a joy to install and look at, these are seriously nice people to boot.    I guess they dropped the price on the Stryker motor mount by $10 recently, and decided to issue credits to customers who had recently purchased at the old, higher rate. 

Nobody does stuff like this anymore, and my hat is off to Gary and his folks. 

The Hobbycity 36mm motorwas heavy, but it balanced – Now that I have the motor in hand I realize it’s a car motor – I took it out with a Graupner 6×6 prop installed, and the thing flew great until about 100mph again, at which time it started corkscrewing all over the place.  I’ve decided that I’m going to glass up a new airframe before going any further, this airframe is trashed.

- Eli