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Audacity Audacity Pantera Helicopters Support


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Old 02-19-2012, 10:11 PM   #1
forvols
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Trying to get my Jet Ranger ready for Birmingham even if it's in a non painted state. It turns out that the more you do with this thing, the more there is to be done!

I spent a whole afternoon working out how I can get the tail control rod going on this project. I have flipped the tail rotor over to the left (port) side of the helicopter because I feel that leaving it on the right (starboard) side is just too much of a deviation from scale to live with. No, my project will not be a competition level build, but leaving the tail rotor on the wrong side would be like building a P-51 mustang and not putting a belly scoop on it.

The problem with flipping the tail case over so that the output shaft is on the other side is that the control arm winds up at the top of the boom rather than the bottom of the boom. Remember our Pantera control rod (like all other pod & boom models) is on the bottom of the boom and ther really is no easy way to run a control rod on the topside of the boom.

My initial resolution was to simply use a boom mounted servo mount and mount the servo on the top side of the boom. This would have been a very easy task and there is enough room in the doghouse portion of the Jet Ranger fuselage to accomodate this. The problem is that the control rod wound up being to high toward the rear of the fuselage boom requiring some fairly significant surgery on the top side of the fuselage, and the manufacture of a custom cover/fairing to accommodate the rod. I went in search of other ideas as I felt the problem was severe enough that there would be no way to resolve it while retaining anything resembling a scale look.

I considered trying to glue a wood servo mount of some sort directly to the fuselage (rudder servo would not have been installed on the Pantera airframe at all). This idea I think would be feasible, but seemed like a lot of work and I'm not sure of what other complications this route may have caused along the way to completion of the project.

I finally decided the best approach would be to try to craft a tail rotor control arm on the bottom side of the boom. The stock control arm is located on the top side due to being flipped to get the tail rotor on the proper (scale) side. After looking at the space beneath the tail boom inside the fuselage, Dale and Darrell both pretty much agreed that running the tail rotor control rod on the bottom side of the boom made the most sense. The obstacle here is that you can't just take the control arm off the tail case and flip it over to put the arm on the bottom. Plain and simple, we would have to craft a control arm and mount it to the bottom of the existing tail control arm. Fortunately for me, Darrell just happens to have a good bit of scrap G10 fiberglass from which I could cut an L shaped control arm from.

After taking way to long, I finally wound up with a functional (but certainly not sexy looking) control arm. Mounting this new arm to the bottom of the existing control arm assembly would require securing it to the existing lower arm utilizing a shim and a few screws. Minimal clearance between this new control arm and the tail case resulted in the need to basically counter sink the control ball screw so that the head did not protrude below the surface of the new control arm.

Using a carbon fiber tube and threaded rod ends and tubing from Dale, I will make a carbon fiber control pushrod which will allow me to forgo the use of the stock control rod guide stations, hopefully making removal of the airframe from the fuselage somewhat less cumbersome, (it's still gonna be a PITA to pull the airframe out of the fuselage for any kind of maintenance).

Tomorrow afternoon, I will finish the carbon fiber pushrod,
get the tail servo mounted, and the pushrod actually installed. After that, it will be time to secure all other servos in place and get linkages set.

It's not looking like I'll have this fuselage flyable by Birmingham, but I will most likely have the airframe flyable in pod & boom configuration. Well.. now that I think about it, the Chief Domestic Financial Officer will need to approve a small chunk of money to get things like blades, batteries and various other items necessary for completion. We'll see how that goes .

So... at the end of this building session today, I walk away with even more respect for those of you who not only tackle the engineering aspects of putting mechanics into scale fuselages, but actually enjoy it. In my mind, this was simply a matter of is there enough room for the mechanics to fit inside the body. As it turns out, there is nothing as simple as putting something in place and bolting it in. You don't think about things like, "how do you get the the boom/tail case in place. How do you go about getting proper tension on the belt when you can't get to the fuselage bolts to loosen and tighten the frame clamp at the tail boom? How do you make linkage adjustments on the head/servos when you can't even reach them from within the fuselage". Everything is a challenge, and solving one challenge often time seems to lead you smack into another one that you had not anticipated.

Hats off to you guys!

I thought that the Jet Ranger would make a very easy 1st scale project. In retrospect, the MD-500 would have been a bit less stressful as you can get away with simply letting the stock tail case stick out the back of the MD500 fuselage boom. Not the case with the Jet Ranger.

I will say right now that having access to Darrell's workshop has been a huge blessing which has allowed me to implement a few ideas with a good deal of precession rather than my typical redneck crudeness.

I'll post a few pictures of my modified tail case and tail control arm within a couple of days. Nothing sophisticated, but perhaps something that may help others down the road who might have similar issues to try to resolve with their own scale builds. I don't claim my solutions to the challenges that have been presented are the best. I suspect that there may be many different ways to skin the cat, but I'll post how I did it.

I'm pretty sure that this will be my paint scheme....

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Last edited by forvols; 02-20-2012 at 04:27 AM..
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Old 02-20-2012, 01:44 AM   #2
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Like normal, you do a great job explaining how you go about having fun with our hobby. I like to problem solve and make things work that normally would not work how they are originally designed. This is fun for me. I have spent countless nights unable to sleep till I find the solution. It is just how my mind works. Sounds like you guys, with some time, managed to figure out a way to make the tail work. Way to go. One day, I would love to get my hands on a fuse to do a scale project. You and helipainter (among many others) inspire me. So glad I got back into the hobby of planes and helis. Although my wife is alway surprised at the costs. Thanks, Todd
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Old 02-20-2012, 07:11 AM   #3
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I'd much like to see a photo of your new control arm. You're not the first to flip the tail case for port-side tailshaft output and while there's no way I can afford to make a mold for 10 people, I remain curious of what others have done.

Of course, mounting a tail rotor servo on the port side is easy since the Pantera has two mounting options in back. What's not so well recognized is how easy it is to start with the stock wire pushrod below and wrap 180 of boom during the run and end up on top. Amazingly, it works quite well.
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Old 02-20-2012, 08:04 AM   #4
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Quote:
Originally Posted by jbeech View Post
What's not so well recognized is how easy it is to start with the stock wire pushrod below and wrap 180 of boom during the run and end up on top. Amazingly, it works quite well.
ROFL...I actually had a fleeting thought of this possibility but quickly dismissed it thinking it would generate too much of a bind and would quickly wear the little red balls.
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Old 02-20-2012, 11:01 PM   #5
forvols
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Default PIcs of my modified tail case for port side output

Took a few pictures of my tail case which has been modified for use in the Jet Ranger. The tail case will be mounted 180 degrees from stock position, which puts the tail rotor on the port (left) side of the helicopter instead of the starboard side. The real helicopter has the TR on the port side and imho is too big a detail to ignore.

You may notice that I have whacked off parts of the tail case that are no longer relevant for use in the scale fuselage. The biggest hurdle to flipping the tail case is coming up with a way to route a tail rotor push rod. Simply flipping the tail case over puts the control arm on top rather than the bottom, and removing the stock control arm and flipping it upside down will not work as the portion of the arm that has the pins which engage the slider ring will be pointed toward the front of the helicopter instead of the rear where the slider ring lives.

My solution to the problem was to craft a new control arm from some scrap G10 material and then attach it to the existing TR arm by running a 3mm screw through the pivot location and using 2 #0 screws to screw the G10 arm to the existing stock arm assembly.

Certainly not sexy or well finished, but looks like it will be very functional. Before you ask, yes... the ball link will slip over the locking nut and snap into place on the ball

**** EDIT **** the 5th picture showing 2 tail cases (P50 TR Case Custom Ctl Arm_05)
is a comparative shot between the stock tail case (on the right) and my modified tail case/arm on the left. IN the last picture showing 2 tail cases, the stock case is on the left and modified case on the right (P50 TR Case Custome Ctl Arm_06).
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Old 02-21-2012, 05:55 AM   #6
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Well done.
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