Wednesday, June 20, 2012

Starmax P-51D Big Beautiful Doll Rimfire 60 Upgrade


Starmax's gorgeous P-51D is a pretty slow as shipped.  The plane gets a significant speed boost from a 5-cell upgrade alone, but the 4S-advertised motor sometimes balks on static runs to include takeoff.  In the air it seems to run fine and the big 4-blade sounds great. But is it fast enough to evoke thoughts of a V12 Merlin?  Maybe not.

At Z8RC, we don't cope well with sluggish warbirds, especially P-51Ds.  Call it a mental disorder.  It actually hurts to watch a vicious warbird airframe quietly paddling along like a broken wild animal that has lost its will to fight.

Starmax's nicely scale P-51D airframe screams for more speed.   It would one cruel act of torture to force the big Mustang to play nice, like some 1980's Chrysler K-car pretending that what people really crave is slow motion efficiency and resource squandering sensibility.   As if watering down products to a state of uselessness magically makes them more desirable.  It all makes me want to puke.

In an attempt to give the Mustang a proper personality, I learned a two things.  First, it's pretty hard to make a 63" chunk of foam hurdle through space.  Second, it's pretty hard to make a 63" chunk of foam hurdle through space.  Enter the well built Rimfire .60, 50-55-650 Kv electric motor.  It shares guts with the lower kV Rimfire .80 50-55-500 Kv .  The Kv gearing could be addressed alternatively with prop pitch, so the two are close cousins.  Aside from being a milled metal monster, the Rimfire motor is surprisingly efficient, not like the failed Power 46 experiment which guzzled electrons to little effect.

I think the .60 upgrade was a success.  This flight used a 14x8 Master Airscrew K-series prop and is running on 6S:

The Rimfire .60 was easy to install.  After unscrewing and removing the stock motor and mount, I sandwiched a standard 1" diameter PVC pipe coupler (50 cents) behind the Rimfire's beefy X mount bracket and the firewall.  Then I drove four long deck screws through the holes in the X bracket, past the PVC spacer and into the firewall, secured with a dab of Gorilla Glue on the point of each screw.  Done.