Thursday, December 15, 2011

Parkzone Spitfire Mk IX - $10 Landing Gear Retract Tutorial

Wind has prevented flying, so it is a good time to upgrade.  

The Z8RC Mk LFIXe Spitfire (now with a big honkin' 4-blade APC 11x6x4 clipped to 9.5x6x4) hauls a$$ on one LiPo cell for each prop blade.  But I thought... you know... this thing could go even faster with retracts.  So it had to be done.  
 
Rather than fork out a mind numbing $85 for the E-Flight retracts plus $4 for the pre-bent struts, I decided to go with the same servoless retracts I recently installed in my P-38.  Total cost is $24, and 20% of that was the Parkzone pre-bent retract struts.

I bought the recommended E-Flight 10-15 size retracts a long time ago for my PZ T-28 Trojan, they are well made, but they don't lock down as solidly as these extremely stout  $10 (32g) retracts from no name China. For $1 more you can even get a metal version, which I didn't notice until after I bought mine.  They ship with no struts (except the steerable nose gear, which is n/a to this tutorial):
I wasn't sure if I should buy the pre-bent Spitfire gear sold specifically for retracts or modify the existing gear, but for $3.99 it seemed worth the money.  As it turns out, the extra strut length, above the spring, of the pre-bent retract gear was required so I'm glad I did.
This set of retactable gear is a close fit, but it is not perfect, mostly because it is a little beefier and stronger than the E-Flight 10-15 retracts. The screw pattern is the same.  Weight is 2 grams heavier per gear unit.  The finished product is perfect in gear fit and function, even better than the E-Flite retracts I've seen installed in Sptifires.

No adjustment or bending of the retract or the landing gear itself is required.  Once installed, both the wheel and the piano wire strut completely disappear into the wing from the airstream, gear doors would be an option.  Vertical strut alignment in the gear down and locked position is better than the stock gear.

Even while making the modifications to the gear well, below, total installation took less than an hour to figure it out as I went along. If you follow this tutorial, it won't take that long.

The plane is pre-wired for retractable gear. Pull the connector out and stash any extra wire in the back of the stock under-wing air scoops.

Step 1:  Remove the original gear and find the pre-wired connector.
Step 2:  Remove the bottom plate to make room for the slightly bigger retract.  I keep an old soldering iron on hand to cut plastic and melt away foam.  A Dremel with a router bit could work too.
Step 3:  Shape the gear well.
Step 4:  There are two 1.5mm hex nut set screws on both sides of the strut where they insert into the gear housing, each set screw is inside a brass fitting.  Tighten them lightly against the strut at first, so you can still slide it in/out to center the wheel in the well and turn it to the angle required during a test fit.  Then remove the gear and tighten the set screws down

Step 5:  Cut the cover plate that comes with the pre-bent gear (or leave it off ).  Even as shipped, this cover plate leaves some black showing on the far side of the two rear  mounting screws.

x2 and done!!