bigbird3

P-40 driver, don't worry about weight in a large plane. Really! If you get them really light you will end up with a plane that gets tossed around in the wind. Cedar Park, that is in Austin, right? Windy there! I lived in Corpus Christi and it is the windiest city, average 18 mile wind year round! I'm in Vermont now and it still applies just not so much. A heavier plane will fly more scale like. After all, it is a scale plane not an aerobatic plane or power house unless that is what you want.
Just a thought from my perspective. Been doing this a loooong time!
bird.

TonyBuilder

My Feedback: (11)

I agree, I live in Austin and we get more wind then less so I like to build on the heavy side as to fly in 10-15 wind. The lighter planes do get tosed around a bit.

TB

P-40 DRIVER

That's a good point, in the past, I've mainly been flying .60 warbirds which have heavy wing loading so I had not thought about the wind issue. I was just concerned about the power to weight issue with a .91 four stroke.

spaceworm

To quote cubcrasher Post #3121:

"Yep that's the CW. I have the 1/4 full wing with a Magnum 91FS on it. I like the way each one flys.
Putt around with the full wing, go full boar with the CW. The acrylic enamel will work with gas or glow. I like
to get it at Oreilly's auto parts. They will mix up small amounts for you. I applied it with a foam brush. You
will like the CW with the 180 in it."

Sincerely, Richard

thebighawg

Got my picklefork done
Big Bird..ruined one 4-40 getting the bend right but I had a bunch anyway I had bought at a swap meet. Used hardwood dowel. Thanks

thebighawg

I thought your technique was cool also Spaceworm

bigbird3

Good deal Hawg, pretty simple once you do it but kinda hard to explain in twenty words or less! LOL! Glad it worked out.
bird.

thebighawg

Running pull pull for rudder today..then on to cockpit detail or might accidentally do a little covering..looks like I may have to do some fairleads for the places the pull pull exits the rear..measured last night and balsa stick seems to be smack in the way of the exits..not thrilled about it..would rather have a straight shot..might try crossing them to get the right angle but popular opinion says to avoid that..chance of rubbing together.hmm

bigbird3

TB, My 24-26 pound Hostetler Piper Pawnee came in at 34! She flies great with a Q-52 (Quadra). Pretty much on the upper end of scale power.
See in my Gallery.
She's a little fat liker her daddy! hehe! Just remember, you should never over plane your engine but over engine your plane! You can't add power if you don't have it but, you can cut the power if it is a bit too much. The difference in weight and cost of up grading is minimal but it is also less costly than re-kitting your airplane.
Another little thought is; heavier is stronger and stronger is better. NEVER BUILD IT LIKE THEY SAY TO! LOL! If you think it is weak in an area, especially in the tail, add structure. That upgraded engine will take care of some if not all added weight. Another 'just remember' in case you didn't already know is................for every ounce tail heavy, it takes four ounces to balance!
The bigger you get and the closer to scale size, the closer your ARE to full size reactions such as less power to weight ratio and torquing into the ground when too low and too slow with full power! It's a whole new ball game when you step up from the 60-120 size!
bird.

thebighawg

Anyone ever rig their pilot to move? I've done it on other builds..pretty cool to see him look the way he is taxxing ..I've done it old school off rudder servo and also by mounting micros in the torso of the pilot..cool

thebighawg

I agree on the weight comment BB..I've always beefed up my builds and tried to stay at upper engine range when my wallet allowed it. I think every one I ever augered in was do to being underpowered.

spaceworm

Attaching the cable ends at the servo arm to the top on one side and the bottom on the other side will help avoid rubbing together. I use ball links with the socket side cross drilled for the cable to pass through, after which the cable passes twice through crimp sleeves before crimping. I use adjustable terminations at the rudder ends.

Good luck and Happy New Year to You and Yours.

Sincerely, Richard

rickj

My Feedback: (213)

Hello,

I would like to join the Cub brotherhood.

Thanks, Rick

rickj

My Feedback: (213)

Hello,

I would like to join the Cub brotherhood.

Thanks,
Rick

bigbird3

Just another thought here, if you are in a position while building and before covering, you can 'cant' the servo and mount it at an angle. This will narrow the cables but then they are at angles, i.e. up and down instead of strait to the exits. I like to use pulleys inside to adjust the angles if possible. The 'box' stores carry a neat little pully that is used to replace worn out grooved wheels for sliding screen doors. They are already mounted with a bracket and flat steel arm with a hole for the mounting screw. You can either us it like it is or drill out the aluminum rivet axil and mount it on a bolt. I used them to set up the cables from my water rudder to my rudder on my float plane. I bolted them to the dural aluminum gear and twisted the steel tab to line up direction.
Never let cables rub on any structure as they will wear a groove and loosen. I know you probably know that but I said it just in case.
What spaceworm said about putting ball joints top and bottom of servo arm is a good way also if it is all you need.
bird

thebighawg

Crossed em..took care of prob thanks bird

John_M_

That's a good idea bird using the screen door pulleys, but a bit on the large size for 1/4 scale... I plan on using some home made pulleys to animate the flight stick in the cockpit; utilizing some pull pull cable coming from the aileron servos in the wings, down the aft side of the forward strut and into the fuse, and then connected to the flight stick... haven't figured out the control linkage for the elevator animation side of the flight stick yet... either way it needs a spring or something to prevent loss of aileron / elevator control if the animated flight stick were to bind or seize up... springs inline on the control cables to the flight stick with enough resistance to allow full range motion, but soft enough to allow the aileron servos to overcome the springs if the flight stick locks up, or if the pilot figure gets displaced and jams the movement of the flight stick.... I'm not going to lose the plane just because the pilot decides to get out of his seat an move about the cabin during some stall turns, or inverted flight ... you know how these scale rc pilots are, they're never in the same place they were in when you first took off... I guess that's why they make seat harnesses, but it still needs some safety measures in place just in case.



John M,

cubcrasher

My Feedback: (6)

Maby some springs like on the 1/4 Cub tail wheel assembly?

spaceworm

How about micro servos "Y"d with the aileron and elevator control servos to animate the cockpit stick. Binding should not then cause primary control failure. Just a idea,. never did it, but may try it sometime. Some use a servo to turn the pilots head with rudder movement.

Sincerely, Richard

John_M_

The micro servos are good idea spaceworm, that had crossed my mind, but if the animated flight stick got stuck for whatever the reason, I still wouldn't want a stalled servo on the power buss for any length of time, so I would still put some sort of override spring even with the separate micro servos... my thinking was to add another scale element and simulate the aileron control cable, but utilize its movement to manipulate the flight stick.

Cubcrasher, the tailwheel spring could work for the elevator side of the animation control linkage, since it will compress, or stretch with the elevator servo push / pull movement... for the aileron, maybe some light weight "tension" springs, that are setup with some pre-tension on them to keep the cables taught at all times, but with enough stretch left just in case something binds... something to sort out when the time comes... I definitely want to animate the sticks, but it has to be done in a way that it doesn't cause any problems.


John M,

Cub Man

My Feedback: (50)

Guys I have the controls in my L-4 working. The throttle set if by a flex cable from the throttle servo. The elevator on the yoke is controlled by the elev servo, I did use a mico servo for the aileron movement. The rudder peddles are spring loaded to pull to the front but the cable installed to pull them to the back. I did have the micro servo to lock up one time and the board in it burned out.

John_M_

Cub Man, I had forgot about the rudder pedals... the return spring sounds like a good idea... having separate micro servos is not always necessary, it adds a bit more weight, which isn't that big of an issue, and it requires power to drive them... I think utilizing the primary control servos and eliminate the potential for binding and put safeguards in place in case they do bind... some lightweight fishing lead from the rudder servo around a small pulley to each rudder pedal with a return spring would be a safe method... it all depends on the space required and the practicality of it.

John M,

bigbird3

John, Spaceworm is right about the 'Y' and a slave servo. That is what I used in the AMR cub, Just a micro servo and perhaps a bit of Sullivan golden cable to allow for flex. If you can make the cable long enough to have that flex instead of a short piece that might be too ridged. I put the elevator slave servo under the back seat and created a card stock apron to hid it. The golden cable looked just like the control cable and the rear stick. If you have enough room to put another servo in the same place, you can solder a small tiller arm on the cable and hook the other slave arm to it and the cable will flex enough to rotate left and right. The distance traveled by both servos will probably be minimal enough to act as a universal joint so to speak.
I even made the throttles work with golden cable. Not too difficult but just time consuming and tedious!
A cheap HS-55 is a great candidate for the job. I used a couple of grand wing servos. If I can find some pix of my set up I will post them.
bird.The throttle quadrants are under the covering. If you look closely you can see the golden rod sleeve between them. Unfortunate! I should have buried it in the side a little more or used the very small cable with a smaller diameter sleeve. I used a dowel at the bottom of the covering to suspend it so the covering wasn't ironed to the sides and pick up the wood grain. The second pic shows the pulleys for the rudder peddle cables, smaller size golden cable, and a slave servo was mounted upright with an e z connector in line to cross the cables. As was mentioned, the front peddles are sprung forward to create return. The pulley sizes are no issue if they are buried inside the plane. then there is no need to make them to scale or otherwise have to figure out how and what to make them out of. As you can see, the control rod for the elevator is like a universal joint. The e-slave servo can be placed on it's side on the left and the AIL-slave can be set up on the right and all hidden under the seat even in a 1/4 scale. The sticks were made form K&S brass tubing with a brass rod through the tube connecting the sticks with both ends hammered flat and drilled for bolts. The mounting brackets are from 'U' channel.Don't have any close ups of the construction. The stitches on my wrist was a ganglion cyst that was wrapped around my artery! The scar looks like a scorpion now!
That is all the pix this session will let me put on. If I find any of closer detail I will post them.

John_M_

Bird you mean to tell me you animated the throttle levers, damn, and you think I'm anal ... now you got me thinking, again, lol

You got the 1/3 scale advantage though... btw, I like the way you covered the interior side panels in fabric, it looks very scale... I bet that cub looks gorgeous fully assembled ready to fly.

I haven't written off the use of micro servos, I just want to weigh all options and use what works without too many headaches, space being a deciding factor.


John M,

bigbird3

It was quite a feat John. I used brass rod for the lever handles and flattened them at the bottom and then drilled two holes. The bottom for pivot and the top hole to link the cable. I used ball head map pins for the balls. Just heat the rod and press it in. Flatten the end a bit to create a 'buggar' to hold it in the ball. The cable came out the back and looped around to a servo.
Thanks on the covering complement. Believe it or not, the front fuel compartment is covered too! I used dowel every where to simulate tubing. The black straps, brass strip, in the rear was to hold the fabric because it was one piece thru the corner. It was a buggar for sure! I have designed, in my head, new ironing tools just for such a thing. The trim iron is way large and presented many challenges! I covered the head liner too. There is a forward head liner also that removes to put in the wing anchor bolts. The rear deck plate is removable for radio access, not much at that for my two hands full of thumbs! The throttle plate, fuel cut off and trim plates and fake fuel tank are vacuum molded plastic. Bob Dively makes them. They were in molded panels that were designed with side panels and rudder peddles. They were so poorly done that AMR would not sell or include them in the kit. They gave them to me! I cut the pieces out and used them instead. The rudder peddles were vacuum formed over the plugs and had no back! Very cheezy!
The trim crank is a piece of 'threaded end' 2/56 push rod with a fiber lock nut and bent to resemble a handle. very hard to get those small bends with pliers and needle nose.
The trim crank was threaded into the 3/8ths balsa side and glued. The fuel cut off is a ball head pin that come in many colors. Regular pins for the 'bolts' pushed thru the sides and bent over and glued down.
The firewall is 1/8th ply with dowels split in half for panel ribbing. and painted aluminum! All of the wood in the cabin was covered with fabric. Like I said, quite a challenge with a four foot trim tool! Well, it might as well have been!
bird.