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adding flaps to an arf

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adding flaps to an arf

Old 10-26-2005, 09:42 PM
  #1  
paladin
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Default adding flaps to an arf


Well I put flaps in to my Kyosho me109 (20hr of air time) then improved the process and installed them into Bills H9 P-51D (10hr of air time). During the summer I purchased a Evergreen P-51D which does not have flaps so that will be the purpose of this thread. I will also try to address the addition of butterfly flaps during the thread as a lot of you have ask about them.

I find that flaps make the plane so much easier to land in all weather conditions! The problem is that in order to learn to land them correctly you have to unlearn a lot of the sport plane bad habits learned over the years. Quite often this learning process will cost you a plane or two! So it is up to you how dedicated you will be.

There are two types of warbirds those with flaps and those without! With out flaps you have a sport plane that looks like a warbird but does not have the advantages of flaps. The biggest advantage of warbirds is flying a heavy plane on windy days it does not get bounced around as much and landing is much more controllable.

The first step is to find a three view of the plane you plan to BARF (Bash ARF) study it and layout the cut lines on the bottom of the wing with a felt tip marker. Check that it fits the spars, ribs, sheeting on the wing and make corrections to make it easier to install. I want to avoid all stress bearing members, I want 1/4 in of skin on top and bottom of the wing after I’ve removed the flap. The latter is so that I don’t have to jig the wing forcing a recover.

So I’m going to lay out the flaps I want first. They violate my 1/4 in of sheeting rule so I moved the flap LE towards the TE to give me the 1/4 in of sheeting I want on the wing. So the line I’ve marked “A” is the original Cut line, but it only left 1/16 inch sheeting. So “B” is the line I plan to use. The “A” line was drawn by holding a 3ft straight edge against the wing TE in the aileron area. Draw the line all the way to the wing center section end rib and measure the distance from the line to the TE. Mark that distence on the other wing and draw that line. Now line “A” should be drawn on both wings.

Line “B” is drawn ¼ away from line “A” to give enough sheeting to avoid jigging the wing. Line “C” is drawn to clear the glycol cooler.

Joe
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Old 10-26-2005, 09:49 PM
  #2  
paladin
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Default RE: adding flaps to an arf

Some pic's of the two previous planes we did this to.
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Old 10-27-2005, 04:30 AM
  #3  
LDM
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Default RE: adding flaps to an arf

I have also done this before , my next project will be my most difficult its a 73" GSP P40 .
Dont know what I will find when I open the wing . ANy advice as you know it will be a split flap so the top of the wing can not be compromised .
Old 10-27-2005, 12:55 PM
  #4  
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Default RE: adding flaps to an arf

Great topic Joe.

I'm in the same situation as you LDM. I'm interested in doing this on my CMP/GSP/Flair 71" Zero, but with the split flap option. Overall I don't think it would be too difficult to do. My biggest concern is trying not to destroy the covering in the process. I really would hate to have to strip and recover the wing, though it would probably be worth it to strip and glass it instead.

Old 10-27-2005, 06:16 PM
  #5  
paladin
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Default RE: adding flaps to an arf

My process keeps all the covering the ARF came with intact! Having said that I’ve never had the Covering a ARF came with last more than 10hr of air time. Bill insisted that he could make it last and has painstakingly cared for his P-51D’s covering and is now getting to the point were he admits it could use a recovering on the bottom of the wing. If you look at the pic’s of Bills H9 P-51D you can pick out the overlap of the covering we put over the LE of the flaps and the TE of the wing. On the top of the wing we matched it with appropriate colors but on the bottom we left the silver overlap the d-day stripes.

While on the subject of D-Day stripes the actual aircraft modeled by this ARF did not have the D-Day stripes on the top of the wing so I’m debating weather to remove them from the top wing or not. I probably wont, opting to get as meny flights as possible on this plane before a recover is needed.

To do split flaps find the TE structural members in from the wheel well. Notice which way the grain goes in the vertical member. If it goes span wise (structural) or top sheeting to bottom sheeting (Shear webbing), next notice if it goes through the ribs (structural) or stops at the ribs (shear webbing). If it is shear webbing we can remove that with impunity because what we will replace it with will more than make up for it! But there could still be a structural member behind the shear web. There are a number of ways to verify what is behind the shear webbing, the easiest is to use a push pin. You know the shear web will be 1/16, 3/32 thick so if you push the pin in just behind it, it should go right through. Or even put the push pin in a pair of pliers and push it through the shear webbing if a good feel can be gotten from that. But I know that the punky balsa I will be removing from the flap area will have to be stiffened up for flap use and the easiest way to accomplish that is to replace it with ply. That makes that sheeting expendable so I would lay out my scale flaps on the bottom of the wing then lay out the shear webbing over the flaps and cut a x-acto hole in the expendable sheeting to look at the back of the shear webbing for structural members. When doing this remember to make the hole big enough to see things well. Pic's here would be very helpfull to all others thinking of doing this with the same manufacturers plane.

If there are structural members behind the shear webbing, is it balsa or a hard wood? If hard wood that means the member is expected to carry considerable stress. The way ARF's are built I'd bet nothing is behind the shear webs so the first test I would try is to push on the shear web from the wheel well. Now the ball is in your court.
Old 10-28-2005, 07:45 PM
  #6  
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Default RE: adding flaps to an arf

Now before cutting the lines I have to decide how to handle the bind point between the flap and aileron, and the flap and the wing caused by the angles of the hinge line and the sides of the surfaces. I’m making an every day flyer so looks don’t realy matter so I’m going to make the gap between flap and wing large enough to clear there and play the aileron to flap by ear.

The way we handled this on Bill’s P-51D and My Me109E was to make the top line “C” 1/8 in further away from the center of the wing where it meets line “B”. That allows for a nice tight parting line between the surfaces.

To cut the sheeting I used a razor and straight edge, concentrate on making sure the sheeting is completely cut. Then I turned the razor on the ribs pushing it through (about half way each side). You will break some if the ribs see the pictures instead of cutting them, that is bound to happen. For those just make sure you keep all the pieces and once the two halves are separated put each rib back together squeezing the sheeting between my fingers until I can zap everything back together and back to the sheeting. As long as we put it all back the way it was we wont change the AOA of the wing.

3105 & 3107 shows the typical wing rib damage.

3122 & 3119 Shows typical flap rib damage.

3143 flap rib repair, notice the rib tags are gone and the sheeting is glued back down.

3148 & 3150 wing rib repairs notice the missing tags have been replaced and CAed into place. Any cracks in the ribs have been realigned and reglued.

3159 shows two wing parts.
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Old 11-13-2005, 07:42 PM
  #7  
paladin
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Default RE: adding flaps to an arf

I removed the D-Day stripes from the top of the wing after looking at the momokote from inside told me that they were layed over the gray covering. I pealed up the covering with an x acto to lift an edge and pulled it off. It pulled up very easily which tells me I’ll need to go over all the seams before flying.

When I opened it up (cut the flaps out) the rib thickness was a little thin. Plenty thick for its intended use but not thick enough to support a servo with all the center balsa removed(done at the manufacturer to keep it light). If it was 3/32 or thicker with the lightening with the lightening holes or a 1/16 with out the lightening holes that would be fine. So the way I will handle this is to run a peace of shear webbing from top of rib to bottom of rib just behind the aft servo mount. That will tie the two rib halves together and should provide a stable bond joint to stand up over time.

There are two types of servo attachments I can install once the rib halves are tied together, flush mount or in the breeze. Again, I’m building this as a dog fighter for next summer so I want it as simple as possible so I’m going to use “in the breeze” so Lets talk about flush mount first. The flush mount is going to look just like the aileron where the servo mounts to ply and that is screwed to a box in the wing. Both methods are built into the wing the same, I will install two hard wood rails between the ribs. One has the servo mounted to the rails the other has the ply mounted to the rails. So I make two rails per wing that are tight between the ribs where I cut the wing. I will mount one with glue to the main spar on the bottom of the wing. Then from the out side of the wing find the edge of the hard wood and layout the size of the servo on the monokote. This plane has D-Day stripes so I’m going to try to keep the servo in the black stripe. So I’ll cut diagonals across the square I made of the servo’s size on the monokote.
Put small amounts of masking tape across the ends of the diagonal cuts to keep them from tearing any further. Place the servo in the hole cutting the monokote to allow the servo ear to rest against the rail and screw it down to it.

Push the other rail up against the servo after gluing a balsa 1/16 spacer to it. When everything looks good glue it in place, screw the other servo ear to it, if you need to use this to hold it in place that’s ok also. Once the servo is mounted to both rails, the rail is glued to the rib and the compression strips are installed remove the servo and the 1/16 spacer. Carefully fit peaces of ¼ balsa between the hard wood rails on either side of the servo, then iron the monokote to the rails and balsa then reinstall the servo.

Joe
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Old 11-13-2005, 07:45 PM
  #8  
ramcfarland
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Default RE: adding flaps to an arf

Just posting to follow this interesting thread.
Old 11-15-2005, 10:45 PM
  #9  
paladin
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Default RE: adding flaps to an arf

In my case one of the black D-Day stripes runs adjacent to a rib so I will be mounting the servo right next to that rib. It is also the reason for the bay I chose for the servo. Either bay next to this one is also adequate for the servo bay (for that matter any of the bays are acceptable). The limiting factors are servo lead lengths and driving the flap at its center.

3616 & 3618 – Shows the front servo mount which is mounted by pushing in place and Caing. The Caing is accomplished by dropping the glue in place or polishing a pushrod putting one end where you want the glue to do and running the thin CA down the rod.

3647 – servo front screwed into the forward rail, with covering X – cut as described earlier.

3651 – shows the aft servo mount before the compression strips.

3658 – How I hold the pieces in place.

3664 – aft servo mount after compression strips.

Joe
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Old 11-25-2005, 11:44 PM
  #10  
paladin
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Default RE: adding flaps to an arf

I Cut a peace of balsa from ¼ in scrap stock and inserted it between the flap servo mounting rails. I want this wood to press fit between the rails and don’t want to spend hours getting it to fit right because its only purpose is to give me something to tack the covering too. So I cut the soft balsa 1/16in longer than it needed to be. Then cut 1/16 deep wedges out of each end vertically and horizontally ( if any one wants a pic of this let me know). Then puss it into place carefully (a slip here causes a tear in the covering) the v’s we cut in the ends will aloe the wood to fit into place with some pressure. If you think the pressure is to much cut more v’s.

I installed the aileron servos because I plan to install the “Y” harnesses before installing the flaps, infact I’ll probably install the airlines and retracts before I button it up because I have access.

Now to start installing the flaps I need to make room for the end caps for the TE of the wing and the LE of the flaps. The end caps will be made of 1/8 balsa with the grain running span wise. It is not intended to be a stress bearing member but rather as shear webbing between the little bit if sheeting I left on the top and bottom of the wing. I widdled the ends of the ribs back into the wing so they would fit the end caps.

I plan to use robart hinges here so behind the end caps I’ll install some ¼ in balas for a good mount I’ll go into more dept as I do it. One note here the ribs are not evenly spaces and some are not mounted parallel so each hinge mount will have to be fit individually. So it will go slowly

Joe
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Old 12-04-2005, 04:18 PM
  #11  
paladin
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Default RE: adding flaps to an arf

Included here are pictures of the hard point for the control horn. There are two ways to do this conventional and with expanding foam, I prefer the expanding foam but most people do not have the experience to do it. So I’ll describe it first than do the conventional which is what I will use on this plane. My reason for using the conventional method on this plane is that the TE of the flaps have a gap between the top and bottom sheeting instead of being glued together. If the foam gets between the TE and the covering it will bubble out. So the pictures of this are from Bills plane which is a H9 ARF P-51D.

The two part foam is available from tower I’ve inclused a picture of it. I cut and glue in the ply (and use marine ply, not lt. Ply), marking the covering side for where the ply is. When the flap is all buttoned up drill two ¼ in holes in the flap end cap bay to fill with foam. One hole is a fill hole one is a pressure relief, never pour into the pressure relief hole. If you plug both holes the pressure will blow the flap apart so it is good to practice first or get someone with experience to help you. Anyway as the compartment fills the foam will start to come out of both quarter in. holes. Leave it and let it harden, the next day the overflow will cut right off easy.

The conventional method is to put the ply down then put balsa between it and the top flap sheeting not much is needed, I used scrap from around the shop I believe it is 3/32. When putting the ply in you have to know where the hinges are going because if one is going in the same bay as the control horn the ply has to be pushed back to allow the hinge block to glue directly to the bottom sheeting. I’ll explain why it is ok to put the hard point so far aft later when it is time to hook up the linkage.

Using an X-acto knife and razors I shaped the wing TE cap and flap LE cap to fit into place. A final sanding was used to make sure it fits correctly. The end cap needs to fit with just enough force to hold it in place while the wing is held LE up and TE down, or the flap held TE up and LE down. If you tap it while in that configuration the end cap should be loose enough to dislodge or drop out. The purpose here is simple; if it fits tightly it will deform the sheeting and ruining the seam between the flap and wing. It must be inside of the top and bottom sheeting, no part of the end cap can extend forward of the LE of the sheeting of the flap or aft of the wing TE. Also when removed the open end of the flap spread ( this is the end closest to the root) this is typical of thin wood like I have here (not the case with the H9 and Kyosho). When you look at the flap end caps notice that there is a gap to the sheeting, this is the only area I plan to squeeze the wood to CA it. Accepting there will be some miss match there.

Joe
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Old 12-09-2005, 11:31 PM
  #12  
paladin
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Default RE: adding flaps to an arf

To put the hinge blocks in I had the ½ inch thick balsa wood left over from the me 109. I cut it into ½ x ½ strips and from those fit blocks between the ribs and flush with the bottom sheeting. Then removed the blocks and sanded them to be flush with the wing and flap end caps. The top and bottom sheet on the open end of the flaps spread when I cut it free of the wing so when that hinge block was installed I had to hold it in place while pushing the flap against a flat surface.

On that same end of the flap I had to add end caps. I made the mistake of cutting corners on the Kyosho me 109 and did not put the end caps in on the flaps and the wing, they are both fuel soaked now because I did not close up the area and cover it. To do this right we must go back to when I measured the line. I drew both the top and bottom line at 3 inches from the root rib. The root rib is installed at an angle to give us the dihedral the kit calls for. That means the lines I drew for the flaps were also drawn at the same angle. This is the intended out come, because as the flap is deployed there are pinch points if the flap end is cut square.

Understanding that the ends of the flaps are not square is important because before I hinge the flap I’m going to cut a little of the end of the flap to give me room for the gap and monokote so if I square it up there will be a large gap on the bottom of the wing. You can see in the end shots that I left plenty wood for removal before I run into the end cap.

Joe
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Old 12-10-2005, 04:13 PM
  #13  
Bob Paris
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Default RE: adding flaps to an arf

Hi Guys...
I just picked up an .60 size nock-off P-51 off of E-Bay. This is my second one...the first one, I built up for a friend...after he started it. It's now ready for flight.

True it's a way stand off scale bird, but for less then $150.00 delivered to Hawai'i...not a bad deal at all, and that is a lot of model for the money. True, the main landing gear area is in question, but I reinforce all ARF retractable landing gear structures. It's a light built model, and I can not wait to play with the kit.

I'm going to put flaps on this one and I need to say thanks to the modeler that took the time to put it up here. I have had a Robart retractable tail wheel assy. and plan on toying this instilation. The retract servo can go in the lower fuse. air scoop. There is plenty of room there for it and a hidden access door.

I am thinking of installing air operated landing gear and I am seriously considering this, due to my lousy luck with mecanical retracks...or maybe it's just my landing style and I need the extra help stronger gear give you.

Super Tiger .90, inverted, with a Top Flight in cowl exaust system.

I'm going to put the largest Robart Scale wheels I can fit into the wheel wells. The inexpensive Robart treaded tires grip well on a hard surface, but tend to ware a bit quicker then other makes. The great grip these tires give me, is worth changing them when they ware out. That is if the model lasts that long.

Soft landings always,
Bobby of Maui
Old 12-11-2005, 08:57 PM
  #14  
paladin
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Default RE: adding flaps to an arf

Good luck Bobby!

Mine will be my every day flyer for next year. That has lead to decisions like not hiding the flap, elevator, and rudder servos.

I spent some time on the retracts this weekend. things I've lerned over the years are:

always CA all the layers of light ply together. this model has 5 layers of lt ply for the retact mounts make sure they are all well glued together.

all the joints to the ribs and doublers need to have some epoxy run into them.

any material removed should come from the aft suport.

make a 1/4 inch spacer for the aft ear of the retract mechanisum to move the wheel forward.

if the landing gear mounts are two or three layers of light ply epoxy a peace of hard wood (maple, cherry, walnut, etc.)behind it. be sure the screws bit into it well.

Joe
Old 12-24-2005, 01:42 PM
  #15  
paladin
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Default RE: adding flaps to an arf

Well I’ve got a set of KMP retracts that I thing will be much happier in a 8# plane than in the 13# plane they were intended for. I want to run the air lines before I button up the flap area so I need to install the retracts to know where the lines will need to go. To install the retracts I need to open up the gap between the landing gear rails. I removed all the material from the aft most rail . The reason for this is simple, it is a fact in engineering that any material is three times stronger in compression than in tension. One can then conclude that the rail loaded in compression (aft) can be 1/3 the rail in tension (front). While there are a lot more factors involved in the actual stress to each rail the important thing is to realize that the first point of failure is the front rail.

The rails in this plane are five layers of light ply so for some time I considered removing the front rail and replace it with maple. That would allow me to rotate the retract mech. With out adding spacers behind the aft ear. But I want to see if this setup will work So I used
#6 x 3/4 sheet metal screws to hold down the retract mechanism. Once everything was set up I removed the screws and the retracts. Soaked all the rails and joints I could with CA, also the screw holes. Lastly I painted all the joints with epoxy and foamed all the blocks to the top sheeting.

I’ve also installed the control horns on the aileron and flaps. Please take note of how far back on the flap the control horn is. Basically I set the flaps to work between 0 and 45 degrees, so the hole in the control horn wants to be over the hinge line at 22.5 degrees or half the travel. Doing this will help give good accurate control of the flaps all through its travel. One of the biggest mistakes I see with flap setups is that the linkage is spongy at one end of its travel. A spongy deployed flap will make staying in trim with the flaps deployed impossible, and provide a great deal of frustration.

I’ve marked were the hinge blocks are on the end caps and stripped the covering off were I plan to glass the center section.

Joe
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Old 12-27-2005, 01:07 AM
  #16  
Bob Paris
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Default RE: adding flaps to an arf

Update...

I have received my kit and it's been with me a couple of weeks. I was able to get mine on E-Bay for under $140.00, shipped to Hawai'i. That's a lot of airplane for the money.

I ordered and received my Century Jet P-51 retracts, and they look really nice. I've the Robart tail wheel retract too, and I'm using a 1" air operated ram to all the work back there. Robart 3 1/4" plastic wheels with foam inserts, WWII diamond treated tires. A metal spinner, and T.F. incowl muffler. I'm using a ST G-90 and installing a 16 oz. Du-Bro fuel tank.

I have the Top Flight P-51B conversion, with B canopy and I will have flaps. The model is being recovered.

Most all the airframe work is done for you when the kit arrives...and it's a stand off scale...Ok, really stand off scale. But the way I fly, and what the model looks like when airborn...I sure can't see the all the difference anyway.

Now remember...it's just a hobby. To me...installing these goodies will be lots of fun, and this is a great flying kit.

I will keep you posted, and now you know what my Christmas present was.

Happy New Year
Bobby of Maui



Old 01-01-2006, 11:04 PM
  #17  
paladin
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Default RE: adding flaps to an arf


Now comes the part were it all goes back together. I covered the bare wood and ran out of silver ultra coat and used aluminum monokote and on the top surface the difference in shade is obvious. I’m not going to go back and fix it because I figure the factory covering job is only good for about 12hr of airtime, less than I plan to fly this plane in one season.

I used 3/4in reinforcing tape on the wing center section because that is what the LHS had available. On the bottom I layer over that two layers of 3/4oz. About 7/4 in. wide. I covered over the bottom but plan to leave the top uncovered just to keep an eye on how it looks.

I’ve strung all the aileron and flap servo wires before I buttoned up where the flaps had been removed from the back of the wing so I can get in there if I need to. Hooking up the flaps I plan to use a standard y harness and have the pushrods come off the same side of the servos (ailerons have the pushrod coming off opposite sides of the servo to give the opposite direction movement. Notice that I have mounted the control flap horns centered on the servo not offset to the side of the servo the pushrod is coming off. The reason for this is to keep my cost down. The other option for y harnesses is one that reverses one of the servos (now they need to be hooked up like ailerons, pushrods coming off opposite ends of the servo). Lastly and no longer made is a y harness that allowed one servo to be trimmed to the other. The important thing to have in all these is the trimming feature, when looking at the reversing y make sure it has the trimming pot because that is what you are buying it for.

The first time I use the flaps even with all my attempts to keep the surface area the same (left to right flap), angle is =, servo output arms and flap control horn all move through the same arc it is still possible that the flaps will cause a small role when deployed. It can be very slight ( a quarter or 1/8 role in a pass ) and can be trimmed out by adjusting clevises. But that takes time and for someone who does not understand what is going on they will end up changing the clean flap position also, retrim it and when the flaps come down the role will still be there. So to avoid the frustration I tell pilots new to flaps to use one of these y’s with a servo trim option to trim it out.

So my process will be to fly it with a std. Y and same side servo exits and trim that out mechanically. If I fail at that I will use a reversing y with the trim option requiring me to reveres one of the servo out puts, re-trim, fly, then y trim.

On the plane I install the hinges in the flaps first, making sure the hinge pins line up. Then fit the flaps in place and mark very carefully were the hinge holes need to be drilled in the wing. Before marking make sure there is no binding flap to aileron , or flap to edge of wing. Then drill and install the hinges and check for binding again. In my case I had a bad bind on the left wing aileron to flap. I had to cut about a 1/16 of wood off the aileron to get a good fit.

I use ez connectors for the first flights to make the adjusting easier. Pay special note to the position of the servo output arm for both clean and dirty. Also don’t settle for the standard 60 degree movement getting to know your radio can get you 72-90 degree movement.

Joe
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Old 01-02-2006, 04:05 AM
  #18  
Bob Paris
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Default RE: adding flaps to an arf

Happy New Year Paladin,
I've been busy myself...and now well into my mods.

I pulled all the covering off of my fuse, then using the TF "B" conversion plans, cut the "D" top aft fuse off, for the conversion. Next, using the TF plans that come with the "B" conversion, I cut into the bottom aft of the fuse. I did this to give access for the Robart tail wheel retract assy-Robart part #121 tail wheel retract unit, I want to install. It was a snug fit, but it went in...and this was my fist instilation for this unit too. But it went in, with access to some of the unit, but not all of it...once it is all together. Having the aft top off the fuse, for the "B" canopy conversion made this a real simple job. With out that top aft off, it would have been a real hastle.

I was planning on using a 1" air cyl. to do the retract work...but it has yet to make it to me...so I elected to have the tail wheel retacting done by a servo, with the mains, air operated. I will have the rudder servo under the wing, not in back. This was done for two reasons.

I need to control both the rudder, and tail wheel stearing, and with the Robart retract unit in the tail...I had to come up with a new way to control this combination. The tail wheel, in the retract position, moved into the place the rudder servo would need to be...there ain't a whole lot of room back there. I made a cover plate removable for the tail wheel unit, using supports and three screws.

I can use the elevator aft servo position with out any problem, and will place my elevator servo back there. But the rudder servo will be next to the throttle and tail wheel retract servo. The plus side of this is, I will have easy access to servo arm adjustments.

The tail wheel stearing will be a pull-pull system, using small braded wire (in a tube), and this will allow for the proper operation of the retract unit.

I coated the forward inside fuse with deluted 2 hour epoxy. I also place a doubler to where the wing hold down plate is, and will drill and tap for a 1/4-20 threaded plastic bolt-for main wing attachment. I tossed out the kits supplied metal screws.

Next will be to final the retract tail wheel assy, tail wheel stearing, rudder control rod and prep for the engine instilation.

I will build the "B" hood and deck last...it's easer to do it now with everything appart. By the way, the "B" canopy looks really cool.

There is more to come...and I'm kinda engineering this as I go. I'm keeping it simple, and if it looks about right...I will go with it. I am planning on installing wing flaps too, and what size Robart hinges did you use ? I'm not sure if I will use Robarts or CA hinges for my flaps.

Happy New Years,
Bobby of Maui
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Old 01-02-2006, 10:40 PM
  #19  
paladin
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Default RE: adding flaps to an arf

Bobby, looks good! just be wear of all the wt added aft pf the cg. Moving the E and R servos forward will offset alot of the wt your adding back there.

Joe
Old 01-03-2006, 08:43 PM
  #20  
Bob Paris
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Default RE: adding flaps to an arf

Hay Paladin,

I managed to get the Robart retractable tail wheel working with the retract servo now installed into the airframe. I have both the rudder and engine trottle servo's inplaced too. I now am into getting the tail wheel stearing hooked up and figured a way to do this. It's a tight fit back there and work goes slow.

My elevator servo lead takes one 18" extension, but will take a little work to route the wire around the tail wheel retract unit. I am using a used retract servo for the tail wheel retraction...only because I have a good used one in hand. I am using Airtronics 94322 ball bearing servo for the rudder, and a new 94102 for the elevator, in the tail. I use Airtronics gear, and I am really happy with this gear.

I know I am adding a little whight in the tail, but I'm only using one servo back there. I'm doing my best to keep things light, but when I balance the model, I will know. Until then...I'm keeping my fingers crossed. This is also a practice model for me...installing gear I've never worked with before.

I am using a S.T. G-90, and believe the model will have enough go juice to take the extra wieght of the retract sysems. I am using the T.F. in cowl muffler system, and I'm not sure just how much power I will lose with this exhaust system. I've always used Slim Line exhaust systems in the past with good results with this engine.

Do you have any on hands experience with the Top Flight in cowl mufflers ?

What size Robart hinges did you use on your flaps ?

This is a surprisingly well put together model, and light for it's size. This kit acks to be played with, and at the price, it is really resonalble...with out all the building, a standard kit takes to get to this point in the assembly. I can't even buy a build yourself kit of this size, for the cost it took to get this ARF to me in Hawai'i.

Soft landings always,
Bobby of Maui
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Old 01-04-2006, 03:34 AM
  #21  
Bob Paris
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Default RE: adding flaps to an arf

Dear Paladin,

I managed to get my strearing for my tail wheel set up and working well. I installed my elevator servo, and ran the extension forward to the receiver area. Insatalled and hooked up my rudder control rod. Next is the engine instilation...then "B" cocpit and aft upper fuse.

I have a Du-Bro vibration engine mount for my S.T. .90 . I will also install a quick fueler, and 16 oz. fuel tank. My engine will be installed inverted into this model. I have done a 90 deg. side mount for the .90 in another identical model, and we had to do a little cutting to get the Slim Line side mount pitts style muffler to fit into the cowl. This should be a simpler cowl instilation.

Soft landings always,
Bobby of Maui
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Old 01-04-2006, 08:23 PM
  #22  
paladin
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Default RE: adding flaps to an arf

Bobby,
I have one of the in cowl mufflers and have tried to use it with a Super Tigre S-90 unsuccessfully (works greatly with 1.20 4cycles). All the clubs I belong to require engines to be below 96 or 94 db which is accomplished by over sizing the prop and adding baffles to the mufflers. Now that I have set the tone getting the back pressure from the muffler and the extra mass of the prop's mass balanced well enough to allow the engine to run. When I put the in cowl muffler on the 90 the engine acted like it had too much back pressure from the muffler. As the back pressure builds the pressure in the fuel tank builds increasing the amount of fuel through the carb. And the engine eventually goes rich and dies. Unhooking the muffler pressure will solve that problem but cause new ones. The easiest way I've found to elevate the excess back pressure was to drill 1/8 in holes in the muffler until the engine runs right. Of course the engine will get louder, and if you don't know what you are doing you could ruin the muffler. How about mounting the engine at 90 degrees plus 15 0r 30 degrees so that you can run the swinge muffler in the cowl and fuse. Block out the fuse around the muffler.

For fueling I use two formost bulkhead fittings screwed into the cowl. One fitting goes to the tank the other to the carb and I hook the two together with a small peace of fuel tubing to run the engine. The advantage is that all the parts are simple, inspect able, and field replaceable.

Joe
Old 01-04-2006, 09:07 PM
  #23  
Bob Paris
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Default RE: adding flaps to an arf

Hay Paladin,
Thanks for the information about the T.F. incowl muffler, and the S-90. As it is...the darn thing wont fit anyway. So I called Slim Line and ordered an in-cowl inverted pitts style this morning. The Dave Brown 3 1/2" Parabolic P-51 Vortech spinner fits the cowl like it was made for it. Your given plastic spacers for the spinner...and only one for my S-90. I sent them an e-mail on the price of a new back plate drilled for the S-90...I can see me losing the plastic insert spacer. I mounted the engine to the vibration mount and secured it with good hardware. I plan on using for the first flights, a Zinger 14 x 4...whats your feeling on this.

I will next cut out the cowl intake area and mark the fire wall for engine mount attachment. I will have to wait until I get my new muffler form Slim Line to finish the cowl but I will have everything else done.

I ordered the wheel well plastic inserts for the .60 size Hanger 9, P-51. These hold 3 1/4" wheels and look really clean cut and cool. I saw these mounted in a .60 size P-47 and it was a very sharp and clean instilation.

What is a RGW Swinge muffler ?

What size Robart hinges do you use on your flap instilation ?

I can't wait to begin work on the canopy and turtle deck.

Soft landings always,
Bobby of Maui
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Old 01-05-2006, 07:05 PM
  #24  
paladin
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Default RE: adding flaps to an arf

Bobby, the rgw is the with my fingers shifted on the key bourd. where is that spell check anyway.

I used the hinges that are 1/8 dia look at the pic's I photoed the packaging. the mfr stocking number is on the packaging.

got to do the kiddy schuffle

Joe
Old 01-06-2006, 02:26 AM
  #25  
Bob Paris
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Default RE: adding flaps to an arf

Ha Paladin,
I finished as far as I could with the engine instilation, but when my header comes in, I will need to fit it to the engine and trim the cowl to fit the exhaust. The throttle servo cable is in and I have yet to install the 16 oz. fuel tank, but I will do this tomorrow. I also need to fit and final the receiver, battary and on/off switch. Then the turtle back gets started...

I do not have a lot of experience with the ST .90. What fuel would you recomend ? Prop size for this model...I like a hard pull...not high speed for my models. 14 x 4 is what I'm planning on for the first flights. High speed is seriously hard on my WWII fighters.

I noticed that you did not really put scale size flaps on your P-51, wing flap mod. What was your reason for this. My 3 views show a larger flap size. I will re-read your info...I know you talked about this...but not clear to me yet exactly why.

This is my second "B" model P-51. My first was an old Top Flight red kit I built in 1975. I had a K & B .61 in that model. It was fixed geared, and flew well.

Soft landings always,
Bobby of Maui
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