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Old Aug 03, 2008, 10:19 AM
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Gree's Avatar
Sydney, Australia
Joined Jun 2006
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Tailwheel Steering, Servos And Air Valve

Completing the Pull-Pull Tail Wheel Steering
Well I went ahead and finished the tail wheel steering, and I think it will work pretty well if I do say so myself.

I decided to use the hard plastic tubing that came in the Dubro pull-pull kit as guides for the cable to pass through the former I had indicated on an earlier post. Their is hardly any friction to speak of, even when the cables are tensioned up tight. It was easy, and didn't involve me having to buy any extra parts which is a bonus.

When the tail wheel is down, there is a tightness on the cables that gives really good steering with no slop, and when the tail wheel is retracted, there is enough slop in the cables so the wheel does not steer, and the servo won't be straining (the same servo is also going to drive the rudder).

I haven't fired up the servos yet though, so fingers crossed all works well.



Control Linkages
I decided (and when the plane is finished, I think I will regret it) to NOT go with the hidden internal elevator linkage, and pull-pull rudder system. With the tailwheel steering it was getting really complicated in there, and I did not want to have a separate servo to operate the rudder. So I decided to use the standard external elevator and rudder linkages that came with the kit. Not so scale, but oh well. It felt good to move ahead and have the steering work.



Servo Mounting
In order to ensure smooth operation of the pul-pull system, I wanted to mount the rudder servo centrally within the fuselage. The problem with this though was that it would prevent there being enough room for the elevator servo arm! (both servo arms would hit and the cable got in the way of the rudder and elevator control rods).

After scratching my head for a while I went with a very simple solution of raising the rudder servo slightly above the elevator servo in the mounting tray. This means the elevator servo can happily swing underneath the rudder servo arm, and the cables do not foul the elevator linkage. Easy peasy.



Air Valve Mount
Another simple solution for the air valve mount - read the instructions! I just went with the recommended placement by extending the servo tray forward with some scrap ply, and mounting a 9g micro servo to operate the air valve. I have the deluxe Robart air valve so I can control both the retraction and lowering speeds of the gear independently. Looking forward to when I can try that out!

I made a sturdy little mount for the valve, and also cut some ply to hold the rear of the valve and stop it from spinning by cradling its hexagonal shape.




Next task is to finish up the elevators and rudder ready for the standard control horns (I did not build the mounting ply in at the time because I THOUGHT I was going to be clever and do the hidden linkages!), link up the rods to servos and permanently secure the servo tray. Hmmm actually I think I will only do that AFTER I have worked out how my 8S batteries will be mounted.
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Last edited by Gree; Aug 03, 2008 at 10:24 AM.
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Old Aug 03, 2008, 05:07 PM
AMA - 734492
EricClark's Avatar
United States, MT, Butte
Joined Mar 2007
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Way cool! I have to build me one of these someday!!
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Old Aug 03, 2008, 11:45 PM
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Brentwood, California
Joined Jul 2007
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looking good..
keep plugging along

Ron
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Old Aug 05, 2008, 03:49 PM
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mars's Avatar
San Francisco, CA
Joined Jan 2002
577 Posts
I have been thinking of this very build

Watching with interest. The "training" I have is a Ryan P-47 with a 36" ws & mech. retracts. Flies well but I want more detail...and flaps!

Mars
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Old Aug 06, 2008, 03:17 AM
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Gree's Avatar
Sydney, Australia
Joined Jun 2006
2,950 Posts
Thanks guys - felt good to move forward after a bit of a break from building. I am still kind of regretting going the simple route of exposed control linkages, but oh well.
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Old Aug 08, 2008, 04:32 AM
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Gree's Avatar
Sydney, Australia
Joined Jun 2006
2,950 Posts
Quote:
Originally Posted by SCALEFAN
...I can't wait to read the flight reports on all the P-47s, it's the only plane that I haven't done yet.

Al
Does this mean you have the Top Flite Fw190-D9? That is what I really wanted but I could not find it anywhere. I love the D9 and even while building this one wish I had it ready to be built next!
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Old Aug 13, 2008, 05:19 AM
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JoseLG's Avatar
Jerez Frontera (Spain)
Joined Nov 2004
416 Posts
Hi Gree
Good work.


I've just ordered mine. I`ll use the robart retracts, The CJM are very pricey and don`t sell the struts, only the complete set.
Some time ago I buy the retractable tail wheel with the air cylinder and after seen your photo I undertand how to mount it, Thanks again.

Also my favourite planes y the FW 190-D-9 (long nose). But actually I was deciding betwen Hawker Sea Fury (kit) and the P-47D-25. Win the second, for this combat. Next?, Who knows.

Cheers
JosÚ L.G.
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Last edited by JoseLG; Aug 13, 2008 at 05:42 AM. Reason: Spelling
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Old Aug 14, 2008, 09:44 AM
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Sydney, Australia
Joined Jun 2006
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Thanks JosÚ. Glad you are finding this useful. I have stalled on the build again. Just bought a CMP 53" Zero on ebay for AU$100, will get that in the air first as a testbed for battery and motor (plus to practice on something bigger than a park flyer which is all I have flown so far)...


Make sure you start a build thread too and post a link to it in here! It would be great to share ideas as we go along.
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Old Aug 16, 2008, 03:53 PM
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Joined May 2005
419 Posts
Hey GREE, I justordered the exact same setup from Hobby city, except i went with the plush 80a with UBEC. I will be running it on 8S in my TF P-51 ARF. Let me know how it works out! Nick
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Old Aug 17, 2008, 03:41 AM
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Gree's Avatar
Sydney, Australia
Joined Jun 2006
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Actually Nick I think you'll get to fly it before me!

Actually I just got a CMP Zero, so I think the electrics will go into that first, maybe with 6S.

Please do let me know how the set up goes with 8S, I really want to know.
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Old Aug 17, 2008, 09:25 PM
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Joined May 2005
419 Posts
Hey GREE, My P-51 has been sitting around (well..hanging around) in my garage for two months now waiting on a drive system. The whole plane is done with servos and reciever, just needs a motor and power pack. I have been building my Yellow F-18 Twin and spending the funds on that and not the p-51, so now it should fly really soon.
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Old Oct 30, 2008, 03:09 AM
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Joined Dec 2007
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that is really great work you are doing there. P47 by all accounts is alovely flyer and beautiful to land
cheers
Peter
www.petenplanes.com.au
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Old Oct 31, 2008, 02:55 AM
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Sydney, Australia
Joined Jun 2006
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Thanks Peter. I have been distracted from this build over the last couple of months while I have been putting together an electric conversion of a CMP Zero. Its nearly done...

Time to get back to it. Will have updates soon.
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Old Nov 02, 2008, 12:05 AM
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Sydney, Australia
Joined Jun 2006
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Mounting The Air Tank & Stringing The Bottom Fuse

Man it has been ages since I have touched the '47!! But the zero is now complete and its time to get back into it!

Well after a lot of thinking about how to mount the batteries, I decided to make the cowl removable in sections like the real plane, so that there won't be any hatches in the fuse. Balance should not be a problem this way either, as I plan to mount the batteries vertically in the nose section, meaning I can move them back an forward within the cowl a fair bit to get the right balance.


Mounting the Air Tank
Anyhoo... the air tank. Well nothing special here really. I am using the standard tank mounting position. I used silicone to glue the tank in place, but as some extra insurance, I drilled a hole in the rear mount an used a large cable tie to make sure the tank won't go anywhere in case of a bumpy landing.

I have also begin plumbing the airlines in the fuse, but will wait until I finish the wing before I cut the lines to length just in case. I still have not decided where to mount the air filler and pressure gauge... might mull it over some more, but I am leaning towards the firewall (again so I do not have to cut any hatches). We'll see.



Stringing the Fuse Bottom - Tailwheel Modifications
Pretty standard here, except for the rear of the fuse where my retractable tailwheel is. For this I needed to construct a new former and stringing system because the wheel would hit the standard solid balsa block that forms the rear of the fuse. So I made a compartment for the tailwheel, and framed up the area ready for when I make the doors.

I plan to sheet over the tailwheel, make glass doors by laying them up over the balsa (I have never glassed before so this will be interesting!) then cutting the doors out of the balsa skin. I made new stringers to frame the edge of where the gear doors will be cut out to strengthen the area.

Since the solid balsa block will now be less than half the size it otherwise would have been, I hope this has saved some weight back there too!


I am really enjoying building again, especially the custom stuff!
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Last edited by Gree; Nov 02, 2008 at 12:21 AM.
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Old Nov 02, 2008, 07:52 AM
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Springfield, VA
Joined Feb 2000
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Quote:
Originally Posted by Gree
I plan to sheet over the tailwheel, make glass doors by laying them up over the balsa [i](I have never glassed before so this will be interesting!)
I understand the desire to have wheel doors, but it would not be a bad thing to leave them off. First, you do away with the complexity, and second, you have an exit for cooling air. Even assuming you plan to have the belly scoop open to allow this as well, the extra opening will only be to the good.

I would think it would not be that noticeable in the air, just not having the wheel hanging down will be impressive as it flies by...
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