I would not anticipate needing to soak balsa to form leading edge skins. They are not fully wrap around are they? I dont think I recall that.
I typically just sheet them with dry wood, at the VERY most I will  get it in position , and mist lightly with a spray bottle of water, this swells the outside of the sheet and most times allows it to form right around the ribs

I agree that a mist would give enough of a curve,  but his issue is the 1/8 thich LE support (think it might just be 1/8 x 1/4 on the flat) which does not give much for pinning or support weights to hold sheet in place while glue drys.   Wing does not have the typical 3/8 or 1/2 square diamond to accommodate a 2-piece sheeting.

Peter, I still would recommend using Bob Hunts method. You can read it as it's pinned to the top of this forum. When I did the wings for the Bipe, I used  a preformed balsa leading edge as a forming buck.

I know we've spoken about this, and you were concerned that there my be some slight differences that will cause problems. There were slight differences with my wing, but the balsa willingly conformed to the rib shape. Once the leading edge cap was installed, it was easy to add the rest of the sheeting.

A few pics to illustrate:

I would not anticipate needing to soak balsa to form leading edge skins. They are not fully wrap around are they? I don't think I recall that.
I typically just sheet them with dry wood, at the VERY most I will  get it in position , and mist lightly with a spray bottle of water, this swells the outside of the sheet and most times allows it to form right around the ribs

Last night I figured out a solution to the leading edge sheeting problem. It requires some precise cutting to the balsa sheet but it will work. Here is how I plan to tackle it.

I have cut to shape and size the leading edge sheeting. I will carefully align the edge of the sheet with the centerline of the leading edge reinforcement strip. I will support the sheet against the leading edge reinforcement with some tape or other means so the sheet is at a 90 degree angle (vertical) to the leading edge strip. Then from the back side I'll attach the edge of the sheet to the LE strip with CA glue along the seam where it meets the LE strip. (Standard Technique allowing the  adhesive to wick between the surfaces) Once the CA kicks, the leading edge sheeting will be attached toe the LE strip with the sheet sticking up in the air.

Then I'll use a wetted paper towel and dampen the outside surface of the leading edge sheeting and slowly bend it around the curve of the ribs. (after running some wood glue along all the ribs and spar) Once the sheeting is bent around the ribs and conformed to the wing shape I'll secure the sheeting to the spar using standard spring clips or pins while the slower drying glue dries.

After both the top and the bottom of the wing is done then a 1/2 inch strip of carbon veil covering the seams at the very tip of the leading edge should make it bullet proof. The carbon veil should be invisible under the covering film, it is much thinner than galss tape.

Hows that for a solution???

The hardest part is trimming the sheeting so the angles and the length of each panel is correct at the LE, TE, Root and tip ends of the sheet, as once it's attached with CA to the leading edge reinforcing strip there is no turning back.

Sounds kind of iffy, you will only have a 1/16 ca glue joint between sheeting and LE support. 
Thinking it might break or crack the sheet when you try to curve it down to the spar.

Not if I get that area damp enough, Balsa gets pretty mushy when wet. And the supplied sheeting is the really light grain low density stuff.

Attached are the photos of the latest progress. Shown is the adjustable leadout assembly I made up. I did not use the one supplied in the kit as it was not acceptable in this design. I made a small modification to the one George Delany has on the plans as I made a alignment plate out of aluminum to fit over the tubes and to provide a greater surface area that clamps the adjuster in position. I did this over the traditional screw and washer set up because I wanted to make sure the extension tubes remain aligned and to prevent crushing of the plywood slider channel that is typical with the screw and washer setup. Once you have all those dents in the slider rail it adjustment becomes notchy as the washer get hung up in the dents.

Also highlighted is my method for attaching the wing sheeting. The pins you see in the photo do not pierce the sheeting they are inserted into the 1/8th leading edge reinforcement strip. They are positioned so the leading edge of the sheeting sits on the pins, keeping the sheeting aligned 1/16 inch centered on the 1/8 wide strip. Then from the back side I applied CA along the length of the sheeting to glue the leading edge of the sheeting to the reinforcement strip. Once this was set I removed the pins and using a paper towel I wet the outside surface of the sheeting. I then applied wood glue to the spars and rib tops. When this was done I gently rolled the sheeting over the ribs and spars, clamping the sheeting to the spar at various points along the wing. I use the scrap ply from the kit to prevent the clips from denting the sheeting.

This worked out very well and the wet sheeting bend without a problem or any splitting. I pre cut the sheeting to size and shape before attaching it. If there turns out to be any gaps between the ribs and the sheet I'll use CA and nail those down when I flip the wing over. I may modify this technique with the top panels to avoid any gaps between the ribs and the sheeting. The other side will be easier because I'll have more material to pin to and I do not have to worry about maintaining that 1/16 inch tolerance.

Note: In the last photo you can see that I joined the trailing edge sheeting with a 45 degreen angle spanning one inboard rib. On the underside I reinforce this joint with 1/8th balsa cut so the grain is 45 degrees in the opposite direction putting the grain of the sheeting and the reinforcing strip at 90 degrees but no joint angle is parallel or aligns with the centerline of the wing.

Nice job with the LO guide.  Similar to the way I make mine.  I use 1/16 phenolic plates on either side of the wood slider.  Only thing I would have done different is move the slider as far out to the tip as possible.  No reason for it to be buried inside the tip like that.

Progress has slowed a bit as I wait for Tom Morris to make up the pushrods and horns. I got the bottom of the wing sheeted and cap strips installed. I cut the wing away from the building surface. Yo need to be careful during that process as it is easy to have the xacto blade to wander. Do not rely on the balsa to seperate evenly along the perforations. Use them as more of a guide where to cut. The wing is alot lighter that it looks.

A bit late for that as they are now fully imbeded in the wing tip with the tip blocks installed. I'd have to have a real good reason to hack the wing apart to get at them. If you could elaborate please do, before I start covering.

Here is a interesting item. The kit and the plans call for the installation of a tip weight box, which I dutifully installed. (the one in the kit is neat you have to supply your own blind nut and hatch screw though) What I am trying to figure is since there is a tip weight box, why does the plan call for attaching a quarter to half ounce weight permanently to the out board wing tip? And which is it 1/4 or 1/2? Makes little sense to me.

Next I have to cut off the end of the nose by 1/2 inch. I will need to make this a square cut without the aid of a band or Scroll saw. I do not look forward to doing this with my trusty hacksaw blade.

I ended up using 4-40 screws to mount the engine. The 6-32 screws were a much better fit in the engine mount holes but the blind nuts were humongus, easily half again as wide as the engine bearers. On the positive side there is absolutely zero play between the bearers and motor mount pads so I do not have to worry about any engine offset creap.

Note: There is insufficent balsa block to flesh out the cowl or the nose of the model. You will have to piece together scrap balsa to creat blocks to carve the nose and the Cowl to shape. This is very tricky as the plans do not have sufficent detail as to the placement and sizes of the required blocks. You will have to wing it. I hope I have enough wood in the right places to allow mw to shape the nose and cowl without ending up with gaping holes in places. The only guide to this is the photo of the nose and cowl shown in the FM article.

I am awaiting my back orderd spinner from RSM before starting the carving and sanding process. I elected to use a Needle Nose profile spinner as that will let me use a lesser taper to the nose ring on the fuse. A necessity as I have to cut the nose short by 1/2 an inch and that far back there is very litttle in the way of wood to carve due to the location of the motor mounts
and supporting material. By the looks of it I will be sanding into the maple mounts to get the taper I need as it is.

The tip weight specified being permenently installed is to limit the amount of weight needing to be stuffed into the tip weight box. On both of the prototypes, we wound up with about 3/4 oz of tip weight. Any percentage permenently installed will allow less having to be installed in the box.

The amount , 1/4, or 1/2 oz is specified to let the builder decide how much weight he wants to have for adjustments, and is, of course, a choice left to the builder.

Before you shorten the nose, may I suggest you send Gordan an e-mail. He's currently running a PA .61 I believe. He is running the shorter nose, but he may also have found it necessary to add nose weight.  I'm running the stock nose legnth, but my Stalker .51RE is lighter in weight. and I needed no additional trim weight.

The VF weighs in at 12 ozs without the RC carb, add the pipe and I think you have a power package that weighs more than the PA. I already relocated the engine around 1/2 inch back from the plans. So I'm kind of commited, unless I want to fill in the holes and drill new ones. I'll try to PM Gordon again and ask, but as you know he has had other things on his mind.

Can we see a photo of the bottom of the plane to see how the pipe tunnel is covered? Is it open on the bottom? Covered? Or builder preference?

Randy has made a better explanation of the fixed tip weight than I did.

Both Gordan's, and my prototypes are running rear exhaust with mufflers, so the bottom is covered. Gordan has one that Jim Tichey had just finished before he died, that has a PA 40 Ultralight with a pipe. I'll try and get some pics of it over the weekend, when I go visit him.

Memory tells me that the pipe is covered to about even with the CG, open on the bottom, from there to the back. It's really builders preference, but keep in mind the heat has to get out before affecting the pipe too much.

Yes the bell crank is inverted, as shown on the plans. This puts the up leadout in the front. I would have done this anyway as I've been doing this forever. Can't recall now who got me started doing it that way or why, but been inverting the bell crank Since the mid 70's.

While I am waiting for my TOM Morris controls I have started shaping the fuselage nose. Lots of sanding and carving. It is wise to go really slow during this process as it is easy to get too enthusiastic and remove too much material amongst all the compound curves and the like. Resist the urge to Grab a knife and start hacking away. Sand and carve in small areas incrementally, lest you carve ro sand flat spots in areas that supposed to have smooth gradual transitions.

The Nose ring is about 1/16 of an inch over size, so if you accidentally sand into it a little you are safe, but be careful there is not much room for error here. I tack glued the cowl to the fuse to facillitate the shaping process and I suggest you do the same. I have not yet figured out the cowel front end attachment. As I cut the nose short (It is cut to 10 inches to compensate for the weight of the OS46 VF) I can not see how to do a dowel anchoring scheme as Gordon suggests. There is nothing to sink the dowls into. Only have the PLY ring north of the cowl front end.

Note. You will need to carve out the insides of the cowl as well. The insides of the cowl as supplied squeeze right up against the cylinder of the OS 46 VF. When sanding the outsides of the cowl you will have to remember that material will have to be removed from the inside as well.

If you are using a 46VF, I hope you left a lot of room for tank space. Takes a big tank.  

Using a 6 oz tank Hope that covers it. It is a RSM unifow, and yes it is a big sucker will fill the tank compartment completely, especially as I had to shave a 1/2 inch off the nose. The next size a 7 oz would have been too big no matter what.

I've attached the cowl in the front through dowels in the nose ring, and then putting two screws in the back end of the cowl.  You can do it I'd you want, I haven't had a problem using that method.

Well, good luck. You may end up needing a smaller venturi. Pete Peterson uses an OS46VF in his Saturn. Uses a bit over 7oz. I used one for a year (a Tom Lay prepped engine) that used 7.5oz. Most other folks that have used them end up around 7oz unless they neck down the venturi. When I told Pete he would need at least 7oz of fuel capacity, he smirked and put in a 6oz tank. Then had to make a new tank with a hopper to get about 7 1/8oz into the compartment. And he has just enough fuel to finish the pattern. I suggested a smaller venturi, but he liked the power.

Now I'm worried, a 7 oz would not have fit length wise even without a shorter nose. The only available room is down towards the cowl and not much there as thats where the pipe goes. I am going to use a Smith venturi, not sure the dia. But I think it is .275 with a PA needle valve. This plane is quite a bit smaller than the SV11, with a 57 inch span and less squares. Unless any one has any other Ideas I'm stuck with the 6 oz tank.

One thing I know, I cant build a tank, even when I am home with all the proper tools. I've tried in the past and they turned out horrible, leaky and obscenly heavy. I know better than try that again. Unless I can find someone who makes a custom tank. I'll have to take my chances. Unbalanced tank conjurs up all sorts of engine run issues in my mind even if I could build my own. I thik I'm screwed.

Allen is right, I am preparing to use a Sullivan RST-8, 8 oz plastic tank in one of my projects. The tank is 4.5" long X 1.875" wide X 2.25" tall, not counting the little blister for the overflow.

By lowering the tank floor a little, this tank will easily fit into the nose pf the Pathfinder L.E.

I've previously posted a diagram showing how I set up my plastic uniflow tanks. I've been using them this way for years, and never a problem.

Thanks Alan and John,

In the past I have had mixed results using plastic RC tanks. This one will fit and I can push it all the way back against the Rear Bulkhead to keep the weight further back. Especially as all tubes exit forward. On a horizontal plane does the uniflow tube remain on the tank horizontal center line for its entire length? or does it angle up or down? Is a solid oiece of tube inserted between the clunk and the feed tube so the clunk does not fold back on it's self? And dosn't the clunk get hung up on the uniflow tube? I thought I saw years ago a scheme where the uniflow tube was also flexible and was attached to the pickup via a slip arrangement so they both moved in unison. I guess these are the reasons I've had mixed results with clunk tanks. Is there a part number for this tank, so it would be easier to find online?

The Uniflow tube is a solid tube, initially set up on the centerline of the tank. The location of the uniflow being the outermost hole in the stopper precludes interfering with the clunk. It also allows the uniflows height to be adjusted by rotating the uniflow line itself, and is easy to do without taking the tank out of the plane, or disassembling it. You change the apparent height by raising or lowering the end of the uniflow inside the tank.

If you desire, a short legnth of solid plastic, or copper tubing can be placed in the pick up line, so it won't be able to flop forward in a hard landing, or minor crash. I've found the use of the sintered bronze filter,m as a clunk, seems to do a great job of both filtering the fuel, and reducing possible problems with fuel pick up. Virtually all the fuel is gone from the inside of the tank, when the engine quits, and I get little, or usually no surging as the tank is running out of fuel.

The RC tanks I like to use are made by Sullivan, and in the case we're talking about here, is the RST-8. RST relates to the type of tank, the 8 refers to the capacity. The diagram I posted was based on a smaller tank, so to use the larger 8 oz tank, the front view of the tank would be shown with the wider dimension being the to of the tank.

I've used this method of constructing uniflow clunk tanks for over 15 years, and it works great for me. I really like being able to adjust the apparent height so easily.

Others build their uniflows with a clunk on both the uniflow, and the pick up line, or connect things up so the uniflow follows the pickup. It can be made to work, but I do not believe you wind up with the best uniflow tank this way. First, there are two lines that must be flexible enough to allow relatively free movement. Next, the end of the uniflow moving with the pickup, sees varying heights, and pressure differences as both the uniflow, and the pick up move arround. In a hard tank, the unilow does not move around, it stays fixed, and establishes the height of the tank. I think that is why some have problems setting up an RC plastic tank for uniflow in our CL models.  

Nice work, Peter.

I prefer 4" composite bellcranks myself.

Cute thread wrapping on the pushrods.

Hi Peter, It was good talking to you last night. The plane looks great and I can see I can sure learn from your talent! If she's not ready for Flushing let me know and we will work something out.---LOUIE 

The saga continues. I turned my attention to the task of venting heat from the engine compartment. The rule of thumb here is to have a greater area for heat to escape vs the Air inlet area for cool air intake. As I was pondering the layout of the engine pipe configuration it is clear that the items that get the hottest is the engine cylinder, head, and exhaust header. Also heated air tends to rise, I wanted to get some vents more in line with these parts.

Most designers will mainly punch holes in the bottom surface of the cowl, which is great and hides these typically unsightly opening on the bottom of the aircraft. But not necessarily the most efficient solution. I wanted more locations where the hot engine compartment air can exit the cowl. So I decided that a pair of vents in the cowl sides would in order. Now I could just punch holes in the cowl sides but that is kind of ugly. Also I wanted to make sure that air exited these holes and not cause turbulence to hinder the exit of the heated air.

So I borrowed a technique from full size aircraft. As you can see in the photos the holes are not perpendicular to the cowl sides they form more of a tunnel. One that has a greater opening area than the hole is by itself. As air flows across the cowl side it creates a low pressure area across the tunnel opening, the air pressure inside of the cowl would be higher because of the air forced into the cowl front scoop and because hot air expands. The combination of these pressure differentials helps this type of arrangement scavenge the heated air from the engine compartment and the area directly surrounding the exhaust header.

I will add additional opening such as these to the bottom of the cowl as well. To help with the aesthetics I am planning to use some thin wall aluminum tube to line the openings in the cowl sides tapering them to match the shape of the balsa cut out, this will simulate the appearance of turbine exhaust stacks seen on some turbine powered propellor or aircraft.

To create these openings I used a 3/8th aluminum tube sharpened at one end and used it in a rotating cutting dashion to cut the holes, Then some sandpaper rolled into a rod did the clean up.

My other concern was the cooling of the engine crankcase area. Not much I can do there with the structure as it is. The nose being shortened I had to cut away much of the potential inlet area. The outlets would end up under the forward mounted canopy. I did not choose aluminum spinners only for asthetic reasons. I chose them for their heat sinking qualities as well. Being bolted to the crankshaft and the front thrust washers they will help carry away heat from the crankcase and bearings and anything else that comes in contact with the crankshaft. Will probably apply a little electronics heat conducting compound Between the spinner shell and backplate and between the thrust washer and the Back Plate.

The pipe tunnel will get it's own ventilation treatment. Actually they make little 3v fans I could install to move air out of the engine compartment, it would even run on all day single LI 3v button cell. But I think I'll leave that for another project. They are used in hand held portable electronics devices, weigh a couple of grams, pretty cool actually.

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