Chris,
I use almost exclusively pneumatic retracts (Robart, Century Junk, and Rhom) , but do have a mechanical set that was in an R/C model. It seems to me that the real difference is in the quality of the construction. The mechanicals seem to be designed and built down to a lower selling price. Theoretically you could use as high torque a servo as necessary to move the mechanical linkage, but remember that one pushrod will be in compression and trying to buckle. I tried to build a set of retracts for a 1/7th scale Typhoon and set up to test for the CF as follows. Find the CG and weight of leg and wheel. Run a string from the CG horizontally to go over a pulley to a weight. I used a weight 3 times the weight of the leg and wheel. That's about right for 60' lines and 50 mph. Then see if your driver can move the retracts. With the Typhoon--long strut and heavy wheel--all I did was detroy the mechanism I had built. It had a jackscrew drive with plenty of torque. I decided the weight of a sufficiently strong retract mechanism would be too heavy for the model so built it as a fixed gear Sport Scale model. Once upon a time I had an FW-190, 1/8th scale, with pneumatic retracts. They sort of worked after I doubled up the number of cylinders and added a huge balance spring. My models since then have had rearwards retracting gear.

On the other hand, the Mustang gear, especially at the scale you are considering, is pretty short with a small wheel.

If you plan to use retracts as an option in competition you will probably have to retract the tailwheel too to get a good score.

Chuck

Chris, I agree on the size of a model that can handle the "bells and whistles." I have also heard that mental challenges and exercise can prevent Alzheizmers disease. Scale guys should be in pretty good shape (if they don't go nuts from frustration first).
Chuck

Hi Chris,

I also have two of the TF kits withthe "Superform" fuselage skins.  One I started on in the early '70s, and another in the box.

My questions to the scale guys is about the operational features the original kit had.  The flaps, etc., were driven of the three line BC and worked in conjunction with throttle settings it looks like.  Is that still an acceptable way to get operational points in Scale?

Chuck,
      I can't find the rule you refer to. Could you help all of out and tell us where that rule is.

Thanks,
       I did not know that. I have noticed that the rule book sometimes changes things, IE, wording without a rules proposal. I do wonder why.

Chris,

If you are good at sketching out things, you might be able to use a rigid  pushrod to use the CF on the inboard wheel/strut ass'y to overcome the opposing CF on the outboard wheel/strut ass'y -presuming 'cross y'r heart' inward retracting mains.

If you have a reference to hand, look over the way the old Goldberg retracts worked. CG had a compensating spring that gained leverage as the weight of the wheels came to bear. Set up correctly, there was little, if any, change in the torque load on the servo. By mocking that up, with the wingspan direction placed vertical, outboard down (to represent worst case CF) you should find a system that can operate on a standard RC servo.

I did, in 1969 or so, for a stunter. Servos were not as strong, back then. I added a further step-down gear to a World Engines (what, S-14 ?) servo, more for realistic cycle time than for power. Voltage was from a Polaroid camera light meter cell - 4.5V nominal, and the size of an AA cell - 9V battery snap cap ends. Got over a hundred cycles of the gear out of a cell - lost count while it still functioned...

Total weight penalty on a kit-bashed green box Nobler was less than 4 oz. Looked COOL in flight with the wheels tucked away! Since Nobler planform, etc., resembled the pre-war French Dewoitine 520 fighter, that is how the fuse was bashed, and where the markings came from. It had an ignominious end... Trippng 'gear up'  took an over-control UP move, and 'gear down' took an over-control DOWN move. (Circuit like a two-switch hallway ON/OFF light setup, with a mechanical feedback center-off at full UP or DOWN.) Got a too rich flight, requiring whole bunches of handle motion to get a sharp enough turn to hit the switch limits. Hooked the down line over the handle trying to extend gear. Went straight into a muddy field, to the wing roots. THEN - wheep-click, the gear came down and locked...

THAT shouldn't be a problem with a scale ship...

Thanks for the good ideas, Lou.
Chris...

 My vote is for the mechneckal kind instead of the air...but hey?

I have a set of robart retracts...in the box that I had planned to install in a model in a model that I designed called the "Seahawker"  but after building a 1/2 A model of that airplane...I ran out of gas, intestinal'fort-a-tudel-do and then abandoned the .46 Seahawk....

Let me dig through my old box of drawings and crap that showed the installation that was used successfully by my old R/C bud, Ted Dello....who flew those retracts with success in his small R/C pylon racers.
(Ted was a long time Boeing model maker and dear friend in balsa shaving and here is a quickee toon that I did for his retirement party. Wow! That was a long time ago...but I think of him often.
 Chris:
Send me your address and I'll both those Robart retracts and Ted's sketches as a free-beee' "gift horse  LL~care-package?"

Chris,
Was Ed Weiner's Race # 49 black-and-white? (Only saw it in B&W photos, never in color)