samparfitt

My Feedback: (43)

Barry,
I was planning on the robart 165 1" strokes but that 1/2" should be good.

==============
Tail feathers.
Well, I outfoxed myself on the tail wheel servo mounted on the tail gear: Since the wheel sticks out half way, the wheel can't be moving and I'm all out of channels with my JR X9303 transmitter (need channels for choke, canopy, operating cowl flaps and folding wings: 12 are really needed!).
The new tail wheel gear location is on the wing mount using a 4/40 pull-pull system.

pic 1/2:
I used the 1/8" ply from the wing retract mounts to make a tail gear servo mount.

pic 3:
Tray mounted to the wing mount.
I put the tray here so I could easily install/adjust the pull-pull lines.
Initially, I was thinking about mounting the servo on the receiver tray but the cockpit is in the way: I then thought about routing the wires up through the wing mount but the angle from the tray to the wing mount is too severe.

pic 4/5:
The four air lines (retract plus doors) and two servo extensions (rudder/elevator) put into plastic wire wrap found at HD.
I figure it would be easiest to bundle everything up before installing the tail gear former.

pic 6:
New pull/pull wires installed through the former and connected to the gear steering arm.
The wires need to be located low on the former (about even to the steering arm when the gear is down) so when the gear is retracted, the steering arm is about a 1/4" closer to the holes in the former producing the slack needed to render the tail wheel motionless.
(I had to cut the pull/pull wires and re-install them as I had the tail wheel backwards!)

pic 7:
Dry fit (again) using two screws to hold the former in place.

pic 8:
New battery tray cut and installed.
Some large wood screws were used to mount it to the receiver tray, thus making it removable for servicing.
The new tray is 1/8" thick: not worried about weight and, with that short nose, I'll probably need weight up front, anyway!

samparfitt

My Feedback: (43)

Tail feathers (cont)

pic 1:
Initial rudder/tail wheel video test.

http://www.rcuvideos.com/video/F4Uru...heeltest01-AVI

samparfitt

My Feedback: (43)

Tail feathers (cont)

pic 1:
Some epoxy and micro-balls to permanently seal the tail door hinges to the fuse (along with two bolts/nuts).

pic 2:
I'm hoping only a 2"x2" access hatch (side of fuse) is needed for access to the air cylinder for the tail gear.
Since I used a long bolt (that attaches to a blind nut) to secure the end of the air cylinder, and, also, since I have access to remove the four hex head bolts holding the gear to the former, I should be able to remove the entire gear for any future maintenance.

pic 3:
The manual says that the CG is 1/2" in front of the main spar which puts the CG 6 5/8" back from the LE of the wing (masking tape in picture). That's a 5 to 1 ratio of 'back' fuse to 'firewall' fuse: the engine will be sticking out another several inches but I'll probably be glad that I moved those heavy 'D' size receiver batteries farther forward when it comes time for balancing!
There's 5' of fuse behind the CG and 1' in front of the CG.
That's a lot of fuse sticking out the back to balance!

samparfitt

My Feedback: (43)

Engine area (cont)

Functional cowl flaps.
I'll use the same technique as I used on the robart P-47.
I'll first cut along the inside (hinge side) edge of each cowl flap using a razor saw: I'll only saw where the hinge will be so, for now, all the flaps stays securely attached to the cowl.
I'll fit a 1/4" thick ply to the inside of the cowl just past the cowl flaps by a 1/16" for the hinge pins.
The 1/4" thick ply was initially cut 3/4" wide but after checking that the 250 radial is 11.7", I recut the 1/4" ply so it is about 3/8" wide: This gives me a 12" hole in the center which should be enough for the 250 radial.
Initially, I also had four protrusions on the 1/4" thick ply to mount the cowl but those, too, were removed.
I used #1X3/8" button head screws to hold the 1/4" ply to the cowl (later, this will be re-enforced with epoxy and FG cloth).
I cut one side of the dubro (#257 with removable pins) hinge to align with the edge of the 1/4" thick ply.
I then used #1X3/16" screws to attach the hinge to the ply as well as to the cowl flap.
After each flap is secure with the hinge, I then use the razor saw to finish cutting the rest of the flap free from the cowl.
This insures that each flap is in the exact same position before cutting them from the cowl.

pic 1/2:
A razor saw to cut the center of each hinge side of the flap.

pic 3:
I used the cowl to make the initial circle on the 1/4" ply.
The ply is 24"X40" and comes from Rockler woodworking store: very inexpensive and the 5 plys is good enough for this project.

pic 4:
I used what a carpenter calls a 'tick stick' to get the diameter of the cowl at the location that the ply will be positioned.
Two pieces of wood shorter than the total width needed and then pushed apart until the ends touch the desired width and a clamp to hold the 'registered' width.

pic 5/6:
I used some simple geometry to get the center of the cowl center.
I set the compass to half the diameter of the cowl width and picked any location on the circumference and put an arc along the center of the circle. I then picked another location several inches away on the circumference and put another arc along the center: the intersection giving me the center of the circle.
I can now used the 'tick stick' measurement to give me the radius that I need for the 1/4" thick ply.

pic 7:
A band saw works well for cutting the outside radius.
I cut a little proud of the line as it's always easier to take more wood off than add it!

pic 8:
To keep a perfect circle while sanding the radius to the final size, I hold a pen next to my finger and let my finger slide along the edge to draw a line that is parallel to the circumference (this technique to get a parallel line, without measuring and using a straight edge, is good for up to about a 1/2" ).

pic 9:
I use my 8" band saw to sand away up to the red line and test fit the 1/4" ply in the cowl.
I keep making a red line and sanding until the ply fits snug in the cowl (had to do this three times).

pic 10:
The final sanding, I tilted the platform about 3 degrees to get the edge of the ply to match the slight angle of the cowl surface.

pic 11:
The ply fits 1/16" below all the cuts made at the hinge line of the flaps.

samparfitt

My Feedback: (43)

Engine area (cont)

Functioning cowl flaps (cont)

pic 1:
I used the scroll saw to cut the inner circle out of the ply.

pic 2:
Almost the final size.
Fortunately, at this stage, I thought that I'd better check the 250 radial size to make sure it'll fit past the ply.

pic 3:
Here's the re-cut to make the ply narrower so it'll fit past the radial.
The one wide spot is the hold the servos which I hope I can tilt the cowl to get past the engine (bummer not having the engine for a 'real' comparison!).

pic 4/5:
#2X3/8" button head screws to hold the ply to the cowl.

pic 6-8:
First dubro hinge screwed in place and the rest of the flap cut away from the cowl using the razor saw.
One down, fourteen to go!

samparfitt

My Feedback: (43)

Engine Area (cont)

Functional cowl flaps (cont)

pic 1:
Got all the hinges screwed in and all the cowl flaps cut (that's a lot of screws!).
Four of the flaps were pretty wide and I was considering using two hinges on those flaps but one worked out OK.

pic 2:
Andreas at comparf sent me my missing stab tube: yeh.

Gonzalo38

Is the RCS 250 radial the best alternative for this plane ? I mean..... could the RCS 215 be a good alternative or its not big enough ?

Flakbait

My Feedback: (20)

Sam,

Looks great!!

samparfitt

My Feedback: (43)

Gonzalo:
Either radial is more than enough since the manual says to not use more than 50% power on take off with a radial and exceeding 125 MPH may cause structural failure, but 'too much power is just enough'!
A twin 150 would be enough but a DA 150 won't fit in the cowl.

Flakbait:
thanks.

==============================
Engine area (cont)

Functional cowl flaps (cont)
I used some wood cloths pins to hold sullivans gold-n-rod (#506) outer blue tubing to the cowl flaps.
First, I CA'ed some heavy duty auto FG cloth to the center of each flap to hold the blue tubing to each flap.
I then used epoxy and micro-balls to re-enforce the area.
I mounted two hitec hs-225mg mini servos to the 1/4" thick ply (smaller servos probably could be used).
A servo reverser was needed.
If I was smart, I would have pre-cut the holes for the servos but I waited and used a re-enforced cut off disk and an xacto saw blade (#227) to cut out holes for the servos. Since the ply is thick, I have 'open ended' servo holes and will be able to cut off about another 1/4" off the inside edge to make the ply flush with the edge of the servo and, thus, giving me a little more room for the radial.
The yellow rod was then fed through each blue tubing on each flap and two clevises were used to attach each end to the servos.
Two servos are needed to get equal movement along the entire length of flaps.
When I say 'functional cowl flaps': I use this term literally as this will greatly help heat dissipation from the engine.
Since I've only got 9 channels, the cowl flaps will be sinc'ed with the choke: closed choke, closed flaps and vise versa (I figured this was a good 'double up' combo!

pic 1:
Heavy duty FG cloth CA'ed over the blue tube to each cowl flap.
First, I held the FG cloth on one side flush with the flap using a piece of blue tubing and CA'ed one side(or anything that CA has trouble adhering to), and then I held the other side down and CA'ed it.

pic 2/3:
open/closed positon.
The two flaps nearest the servos were not immediately epoxied to the blue tubing until after the servos were mounted to insure no binding at this location.

Test video of the cowl flaps operating:

http://www.rcuvideos.com/video/F4Uco...flaptest01-AVI

NCIS

Sam,

Your right after measuring the distance the doors have to rotate the 1" is the way to go.

Thanks,

Barry

samparfitt

My Feedback: (43)

Yesterday, several of us went up to Wright Pat's museum (40 miles away).
I took 150 pictures but most of them are too dark.

samparfitt

My Feedback: (43)

Tail feathers (cont)

Horizontal stab (cont)
The horizontal stab is removable from the fuse using two bolts that hold the stab to the horizontal stab tube.
There are two kit supplied CF rods (anti-rotation rods) that are epoxied to the front of each stab.
Holes are already drilled in the stabs and fuse.
I had to file the fuse holes very slightly so the CF rod would slide into the holes.
The holes in the fuse are also re-enforced with ply which was done at the factory.
The horizontal stab tube is aluminum and 20mm by about 16" long.
I used the kit provided 3mm bolts and blind nuts for securing the stab to the tube.
There are two 1/8" thick plys that are factory glued in next to the rib, 6" from the inside edge.
These plys are only on one inside surface so make sure you position the stabs so the plys are facing down so the bolts will have some 'tooth' to hold the stabs on as I don't think just the surface molding material is strong enough to hold the stabs to the fuse over a long period of time.
The bolt locations are 5 1/2" from the inside edge of the stab and 1 1/2" in from the TE of the stab.
After inserting the tube into the fuse and putting the stabs on, I used masking tape to hold the stabs to the fuse to insure that they don't slip out while drilling holes through the stab and into the aluminum tube.
I drilled/tapped the holes as I wanted the tube to also have threads to make sure there was no slop between the bolt and tube.
I then removed the stabs and tube and used some tweezers to hold the blind nut while I put the bolt through the hole in the tube and into the blind nut. I then used epoxy and micro-balls to secure the blind nut to the tube.

pic 1/2:
The CF anti-rotation rods epoxied (with micro-balls) into the stabs.
To properly align the CF rods, the stabs need to be put onto the aluminum tube and into the fuse.
To keep the epoxy from going where I didn't want it to, I 'dumped' the epoxy into the inside of the rib at the hole and then inserted the CF rod and spun the rod to get the epoxy on the rod. I then held the stab until the epoxy started to get thick (peanut butter consistency) and then put the stab onto the tube and into the fuse and then aligning the CF rod into the hole in the fuse. I then checked inside the fuse to insure the CF rod was protruding through the hole. I could have put more of the CF rod into the stab as any extra sticking out past the ply in the fuse serves no purpose.

pic 3:
I used a felt tip marker to outline where the aluminum tube is flush to the sides of the fuse in order to insure the tube is even on both sides of the stabs.

pic 4/5:
Here's the re-enforcing ply inside the stabs (sandwiched between the inside surface and FG tubing) where the center is 5 1/5" in from the inside stab edge and 1 1/2" from the TE of the stab.

pic 6:
I first drilled a small pilot hole and then used the proper size drill bit for tapping the hole.

pic 7:
Blind nut put onto the bolt using some tweezers.

pic 8:
Epoxy and micro-balls to hold the blind nut in place.
Candle wax was put on the bolt thread to prevent the epoxy from binding to the bolt.

pic 9:
At 43 3/4" wide, that's a big stab!

samparfitt

My Feedback: (43)

Tail feathers (cont)

Elevator (cont)
The next step is to make up the elevator control horn assemblies.
The kit has solid CF rods but I'm using some CF tubing.
I used the CF tubing as it slides inside the ball bearing's sleeve as the solid CF rod doesn't and I didn't want to sand it to make it fit.
Another reason is the hollow tubing will fit over the brass rod that holds the elevator hinges to the stab, thus allowing the CF tubing to be farther into the elevator for more support.
Inside the CF tubing, I telescoped two sequentially smaller brass tubing to re-enforce the CF tubing.
I drilled/tapped some 4-40 holes about 3/8" from one end of the CF tubing.
I then put a 2" long 4-40 threaded rod into the hole and used dubro's 4-40 heavy duty ball links and a 13/16" long piece of brass tubing to hold the ball link 1" from the CF tubing.
The ball bearings were screwed to the kit provided ply with two #1X3/16" screws (I tried some CA but glue doesn't do well holding steel to wood).
There's too many steps to get the control horns inside the fuse and into the elevators so I first dry fitted everything together and then added the epoxy to the two pieces of ply (that have the ball bearings) to the inside of the fuse.
Once the ply is secure, holes can be drilled/tapped through the elevator and into the CF tubing and some 4/40 bolts can be used to secure the elevator to the control horn assembly. Removing this bolt and the one on the stab will allow the stab/elevator assembly to be removed for future maintenance.
One important point is that I used two CF tubings and will be using two elevator servos: If you are going to use just one elevator servo (thus only one long piece of CF tubing), you will need to wait to epoxy the elevator hinge into the stab as the last step so there will be no binding on the CF tubing going from one elevator to the other elevator.

pic 1:
Holes have to be made into the side of the fuse for the control horn assembly (felt tip circle in picture).
The manual says 38mm behind the horizontal stab tubing but mine was a little longer ( 1 5/8" ): this was due to when I epoxied the elevator hinges to the stab, I first aligned the outside surfaces and then made the inside surfaces equally spaced to the outside distance (which, in this case, made the control horn location a little farther than factory specs). I insured that the elevators had plenty of up/down movement and didn't hit the TE of the stab so this resulted in the elevators being placed back a little more in relation to the stab.

pic 2:
The CF tubing with two pieces of brass tubing.
I applied a little CA after they were together to insure no movement.
I believe I made each one 2 3/8" long.

pic 3:
Here's why I used the tubing over the solid rod: the tubing will fit over the brass rod that holds the elevator to the hinges.
The brass rod for the elevator hinges is pushed inside that hole about 1" deep.
The CF tubing then goes into the hole about 1 1/2" deep and a 4-40 bolt will be drilled/tapped into the elevator and CF tubing.

pic 4:
Two inch long 4-40 threaded rod with dubro heavy duty ball links and a 13/16" long brass tubing to keep the ball link the proper distance from the CF tubing.

pic 5:
The control horn assembly with the ball bearings screwed to the 1/4" thick ply.

pic 6/7:
Once, all parts were dry fitted into place, epoxy and micro-balls were added to the 1/4" ply to hold them in proper alignment.

NCIS

LOOOOKING GREAT Sam!!! I love it.

Barry

samparfitt

My Feedback: (43)

Barry,
thanks, Your giant F4U is also looking great.

===============

Tail feathers (cont)

Elevators (cont)
In this post, I've installed the elevator tray and connected up the servos to the control horn.
I want to be able to service the rudder control horn so I've made the elevator servo tray removable.
I epoxied two pieces of 1/4" thick ply to the sides of the fuse and used four hex head servo screws to attach the servo tray to the ply.

pic 1:
1/4" thick ply epoxied to the sides of the fuse.

pic 2/3:
Elevator servo tray screwed to the ply.
4-40 threaded rod and dubro heavy duty ball links used to connect the servo arms to the elevator control arms.
A servo reverser was needed.
Two HS-645's used.

pic 4:
Two 1" long 2-56 hex head bolts used to hold the elevator to the control horn.
The control horn being the CF tubing.

pic 5-7:
The elevator has quite a bit of throw so I reduced it to 1 1/4" up and 1" down.
The manual says 20 mm which is about 13/16".
The 1 1/4" didn't look like a lot of throw but compared to the recommended 13/16", I may have to reduce it: I usually only used about 3/4" but the plane is so large, it seems like more would be necessary.

Video of the elevator operating:
http://www.rcuvideos.com/video/F4Ucomparfelevtest01-AVI

rt3232

My Feedback: (6)

Sam

First your project is looking great.[sm=thumbs_up.gif][sm=thumbs_up.gif]

Next thanks for all of the details on how to do things, as I see it there is a lot that can be used on things that will fit into my shop.

Cheers Bob T

samparfitt

My Feedback: (43)

thanks, Bob.

=================
Service panel.

pic 1:
I haven't decided where it's going but I got the service panel built (probably just behind/below the cockpit).
I wish that I didn't have to cut any 'doors' for this but I don't see any other option.
I used some 1/8" thick ply and painted it leafy green from rustoleum (#240257: same as used in the cockpit).
Starting at the air fill and pressure gauge (going clockwise):
Soft switch for receiver.
Next two are charging jacks for the two sets of receiver batteries.
Voltwatch for receiver batteries (I like visual monitoring)
Wing pump battery switch/charger.
On/off switch for the voltwatch (so voltwatch is not constantly on when in storage).
On/off switch for the nav lights.
(these last two switches are from radio shack (#275-0407)
The air fill valve and pressure gauge is on a removable ply for future servicing (since they are mounted from nuts from the back).

samparfitt

My Feedback: (43)

Service panel (cont)
I decided on putting the service panel door on the left side of the fuse and forward of the cockpit.
It's located between the receiver tray and former.
Besides being close to the CG (versus back farther behind the cockpit), I can easily access the back of the panel via the wing opening in the fuse.
Since the fuse surface material isn't real strong when cut into small areas, I used a water base contact cement to hold a 1/16" thick ply to the inside of the fuse to re-enforce not only the door but also the surrounding fuse surface.
I used Nelson's 1/2 wide piano hinge (#PH1210) to secure the door to the fuse.
I first cut the hinge side (top of the door) using two 1/30 thick cut off disks mounted together to give the proper width for the hinge pin. Holes were then drilled into the brass piano hinge and then #0X3/16" screws were used to hold the piano hinge to the door and fuse. I usually mount the piano hinge from the inside when I work on a FG fuse but since the 1/16" ply added to the already thick fuse, I mounted the hinge on the outside as the door would bind if the hinge was mounted on the inside of the fuse.
After the hinge is mounted, I then used a 1/64" thick cut off wheel to cut the other three sides. I also used a razor saw with the top 'stiffener' removed so the whole saw could fit inside the slot. Since the body of the dremel keeps me from cutting a perpendicular slot along the doors edge, I always cut from the inside parameter of the door so the angled cut is toward the door which will give a natural lip around the door and help keep the door flush with the surface of the fuse. Cutting the other three sides of the door after installing the top hinge insures that the door will be perfectly aligned with the fuse.

pic 1/2:
A 3"X4" door hole is marked on the surface of the fuse.
These dimensions were determined by the switches/valves on the service panel.
The 1/16" thick ply was cut 4 1/4" X 6" to re-enforce the door/fuse area.

pic 3:
To get the ply to approximate the curve of the fuse, the ply was soaked in water, rubber bands and a piece of wood to hold the ply at the desired curve and then micowaved to make the curve 'imprinted' in the ply.

pic 4/5:
Water base contact cement added to each surface, allowed to dry to the touch for 30 minutes and then the two surfaces were bonded together.

pic 6:
Nelson's piano hinge secured to the door/fuse with #0X3/16" screws.
The holes in the hinge were first drilled and then the screws were easily put into the soft fuse/ply surface.

pic 7:
A 1/64" thick disk and razor saw used to cut the remaining three sides of the door.

pic 8/9:
A little sanding of the edges and the door is 'good to go'.

Jeff4318

Hi Sam just thought Id jump in and say the plane looks great I can see you havent lost your
flare for the finer details. Will the club your with have an open house this year I would like to try to get down there And see you And posiably tour your railroad.I ment to ask you if that is at your place or is it in a club building.Jeff

samparfitt

My Feedback: (43)

Yo Jeff,
thanks.
The local NMRA railroad club is having a tour in April and, yes, my Great Northern railroad will be open for the tour.

==============

Service panel (cont)

pic 1:
At a local flea market, I picked up some 3/8" round magnets and they even had some 1/8" round magnets.
I used a flat end grinding bit in the dremel to recess the door for the 1/8" magnets.
I used a 3/8" forstner bit to drill two holes in some 1/16" ply for the two magnets and then epoxied some 1/32" thick ply on one side (which will be facing the doors making the 3/8" magnets invisible).

pic 2/3:
The door re-attached.
I used a dubro #181 ball socket as a 'door knob' at the bottom of the service door.
With four magnets, the door stays closed with 'authority'.

pic 4:
A dry fit of the service panel behind the service door.

============
Tail feathers (cont)

pic 5/6:
I made the tail gear removable by making it possible to remove the four bolts holding the gear to the gear former.
I also had to make the back of the air cylinder removable which was done with a long bolt and blind nut.
To get to the long bolt, I need a 2"X2" access panel located directly to the side of the bolt/blind nut.
I used a razor saw to cut the access panel out.

pic 7:
Two pieces of 1/16" thick ply epoxied to the fuse to hold the access panel in place.

pic 8:
Eight #0 screws used to hold the access panel to the fuse.

pic 9-12:
a few pictures of the Great Northern railroad.

samparfitt

My Feedback: (43)

Service panel (cont)

pic 1:
Inside view before service panel is installed.

pic 2:
I used the hole in the fuse to get the correct contour of the fuse so I could make two panel supports made out of 3/8" thick ply.
The panel is screwed to the supports and the supports will be epoxied to the inside of the fuse.

pic 3:
I screwed the service panel to the panel supports for any future maintenance work (although I should be able to perform all maintenance work through the large wing hole in the fuse).

pic 4-6:
Service panel supports epoxied to fuse and now ready for 'hook up'.
Later, I'll make a separate ignition panel and door for the electronic ignition and fueling at the front of the fuse.

samparfitt

My Feedback: (43)

Video:

Two full size F4U's in extremely close formation flying:
http://www.youtube.com/watch?v=D6tKD...eature=related

Jeff4318

Sam great video I watched another of a corsair engine start it would be cool to model an electric start in a model if it start like the real thing. they always seem like there never going to fire. Anyway I was at NMRA.com and could'nt find the tour info can you send me a link to find out date and time for your layout Thanks, Jeff P.S. How is Jimmy?

Gonzalo38

Sam:

Do you have a video of the sliding canopy working ? I wasn't able to find one.

I'm ready to place an order for this model. The only thing I still need to decide is if I'm going to use the RCS 215 or the RCS 250. I know you told me the 215 would be more than enough, but everybody seems to be thinking of the 250. What engine was mounted on the one that was presented in Joe Nall ?

IFLYBVM2

My Feedback: (360)

I was wondering the same thing-Some earlier threads in the gas engine forum suggested that the 215 might be more reliable in the long run. Since the airplane is well over powered with the 250 anyway, I was wondering if it might make sense to go with the 215 instead. Opinions ?
Thanks-Mike O