Hi All,

Many years ago, Carl Goldberg models developed a retract control system that used the throttle push rod to drive a servo to operate the retracts.

Would this be acceptable for use under the AMA rules?  There was a limit switch that you adjusted to power the servo.  Low throttle lowered the gear and, of course, you set the limits to raise the gear under high throttle setting.

I am going with a three line system (I have it, and don't have the spare money to get into a full blown electric system right now), and this would be something I can use since I have a new set of this.

Also, I believe the flaps have to be independently controlled. (??) Is there a way to do this on three line that I can understand?

Thanks!
Bill <><

Yes, Chuck, you gave me a lot of great help!  The actual retract system and the problems of centrifugal force is something that takes a lot of consideration, and I had not visitesd that part of the problem!

Having spent 40 plus years flying stnut and general C/L, I am wary of Scale.  Not from a building or flying standpoint, but from a KNOWLEDGE standpoint!  The key to any evnt is "knowing".  And at my advancing age, I don't feel that a LOT of years can be spent on the "education".

A good friend is a member of the US C/L Scale team.  He kinda takes for granted a lot of stuff since he has been at it for a long time.  I wish I had his "knowledge" of the event, I wouldn't feel as apprehensive about it.

Bill <><

Chuck and Bill,
                   I had problems until I discovered a method to make the centrifugal force help in both directions.
On my B24 I had both of the pushrods to each gear attached to a "T" shaped bellcrank. The rods to the gear were attached to the top of the "T" and the power jack screw was pushing on the bottom of the "T". Because the rods were attached on one side for on gear and the other side for the other gear. the centrifugal force acted to neutralize the force. Its like +power on one side and -power on the other. They equal out. The B24 had 4" wheels on gear that was 6" long. It worked perfectly. At the worlds in Kiev in 1988, when I retracted the gear the crowed noise was "OOOOOOOOOOOOOOOOOOOOHHH!!!" I heard it and was quite pleased. The nose gear had it's own servo.

dick

Bill,

Back in the late-1960's I kit-bashed a green box Nobler to look like a Dewoitine D-520 French WW2 fighter, with inward-moving, wing-mounted retracts.

Switch setup was like a 'hallway two switch for one light' system, tripped by - as Paul suggests - a blip of extreme elevator control. Fully retracted, a servo arm switched the system to ready to extend. Gear down switch (other side of a DPDT, actually) was tripped by a blip of extreme elevator. So's I could remember it, Gear Up was a blip of extreme UP elevator, and vice versa.

There were no buffed out gorilla servos back then, so I added a gear to a World Engines S-4 (standard size) servo. Somewhat fragile, but the operating speed was more realsitic, and there was adequate grunt. Like Dick B, I had the centrifugal force help some. The CG retracts - hogged out with a Dremel to about 1/3rd of stock weight - had adjustable balance springs to help lift heavy wheels. Strategically placed 'over-center' arangement... it worked.

I realized the centrifugal problem, so set the balance springs with the model held - guess what? - wings vertical, outboard tip down.

The system worked, but there was always a question of whether it would or not... Plane ended its service one day when I hung the lines over the back of the handle on the down-blip to lower gear. Went straight in, to the wing root, and about the time it stopped, from the handle, I heard the click-wheeeeeep-click as the gear came down and locked.

That'll teach ya... But it sure looked great going through the pattern with the wheels tucked away!!

Agree,

Scale can be 'fun.' ...Including the sense that there's a lot of enjoyment in researching a specific airplane as a subject, then documenting the details, then figuring out how to represent them (at the level of the event - stand-off judging? Fine tooth comb? limitations due to profile fuse? So much else...)

The only thing that doesn't really grab me about flying CL Scale is the comparative limits of flyability. Sure: fast, slow, throttle, in-air 'functions', touch-and-go, taxi laps, shut-down on command... But the proportions of people-carrying planes don't always make for great, or enjoyable, CL flight. Also, their flying envelope is so much more marginal than we're used to with sport or contest CL models.

Scale CL is primarily right-side up for several reasons. 3-lines don't make consecutive maneuvers much fun, for one. The proportions, as above, another. These can make the models skittish. Have you seen the videos of the RC Scale B52? In one there was a reasonable flight from TO to landing, but the thing wallowed around like an RC trainer. NOT B52-like! The other video is its crash. Well, the plume of smoke looked realistic from far across the field. That model had EIGHT big model turbojets! Small fortune, there, just a project to see if it could be done - a question that wasn't answered nicely...

Perhaps I recall several contests 25 and more years ago, where I saw beautifully executed scale CL models that were too little flown in practice, and got outside their envelope in the first few laps. The crashes were not particularly 'realistic' either... And they didn't score well.

Sport-type scale lets us fly the models much more, so that's a thing of the past - if we keep it in mind. The workmanship is a wonderfully challenging, frustrating thing, and when it flies, there's gratification. Small details that "make" the model can be fragile, can come off in frequent flying - another compromise to settle.

But, I'll be back into some level of scale. Keville's 1/2A multi profile idea is just too tempting... As my Dewoitine D-520 story suggests, I like to tinker. CLPA is pretty well settled in terms of equipment functions, and there's a lot of tinker room in Scale...

Guess I'll have to color code my lines - didn't on a few throttled sport model efforts. Flying alone much of the time, I got a lot of walking in, getting the three sorted out... Was dabbling in Carrier at the time, too...

Just about everything CL is great, because it isn't easy. Achieving success to a degree almost always reminds us we can do even better. If it doesn't, things can get boring. Why be bored? Go for the challenge! Well, flying flat and round and round and round without a specific purpose or standard to master can get dull. So race! Or stunt! Or chase streamers! Hi-Lo-Landing! Speed! Scale! Or just tie knots in the sky...  And, you seldom meet as nice a group of people.

It is a given that we have to trust someone to launch for us, and to be sure of that, we have to be trustworthy enough to launch his/her/their models. Makes for getting along real well. (That's my old riff: This mutual trust applies, unless your arms are 60'-plus long. But, then you don't even need lines...)