DaleCS

Have been away from the workshop - outside again, while the weather is good. Made some progress, this past week, as we got almost a weeks worth of rain up here in SE Michigan.

Have gotten the rear panel and floor painted, and have installed my custom made seat belt bar. Dash panel and gun sight are in progress with Chad. Should be here mid-October.






The right panel has been bugging me. It's shown below, on right with a bit of plastic putty filler - waiting for it to dry, filling in a seam gap. The issue I've had is the 5x4 section of bumps, which represent warning lights. These are to be painted red. Hmmm, not very realistic. What to do? Translucent round push pins, beads? Can't find correct size. Visit the train section at the LHS? (TBD) Worbla thermoplastic? Molds well over parts, but doesn't push into tiny hollows, well. Resin casting? Lot of work to make a mold of the plastic and then a reverse mold..

Epoxy? Found a YouTube experiment showing that motor oil makes a good release agent - sounds easy!


In the picture below, in the middle on the wood block, I have a scrap piece of plastic with similar features as the right dash - better to practice with some scrap materials, just in case things go poorly. I've put a thin later of motor oil on and topped off with epoxy. Degassing the epoxy before pouring would be best (despite care, still got bubbles introduced while mixing), but I'm short a vacuum chamber and this is a concept test.





In the next picture, after letting the epoxy (30 min) set 24 hours, I've pulled the epoxy off and sanded the tops off the bums, leaving a bit behind to simulate attachment rings.




Here, I've put the two parts back together, holding some red vinyl behind the assembly, to highlight the effect. Much better? I think so, and easy.

For the actual panel, I've found some red transparent dye from Castin' Craft at Hobby Lobby. There's a brick and mortar close by, so will check there - if not, will buy through their website. This should turn out better than my painting skills could do.

DaleCS

Here's the tinted result, using the right dash panel as the mold. I mixed the epoxy first (30 min) to ensure a good mix, then added about 5 drops of the red transparent dye from Castin' Craft. Also, oiled the mold with motor oil as in the previous test. Washed the part in soap and water to remove any release oil.

Addition of the tint extends the setup time - after 24 hrs, still felt like my dyed part might tear when removing from the mold, After another 24 hrs, though still flexible, it pulled out fine without tearing. The part isn't tacky, and its not as flexible as vinyl, but its certainly not stiff like my clear test piece. Is it still setting up? Or is it done and the flexibility is inherent due to the addition of the dye and part's thinness?

We shall see.

However, its good enough for my purposes. Looks really good with a light behind it, though I don't plan on doing this. Too many other things to complete before adding this detail. If I were to do this, I would have one small LED in a box behind the panel, over my new part, and I'd black out most of the 'lights' by taping or painting a mask over the back of the piece. I wouldn't want all the warning lights on at the same time!




Next - need to sand off the top of the panel light bumps, paint it up, attach my new, homemade warning lights and see if its good enough.

DaleCS

The Precision Eagle 4.2, rebuilt after the Byron's demise, now adorns this ship!

Mounting plate from BJ's Model Engine Service (http://www.bj-model-engines.com/) taped in place. Down thrust angle is built into engine box, per plan. Plate is offset to left of center so that when right thrust shim is placed behind left side of plate, prop hub will be on centerline. Will need 0.111" shim to give 1.5 degrees of right thrust. Plan calls for 1-2 degrees , so I put it in the middle. Still need to make shim, but go eager to see the plan standing on its wheels with engine on.



View from inside engine box. Byron used t-nuts - flew plane for almost ten years with no issues. However, for the number of years flown, actual hours/flight count was fairly low. So, I took recommendations to use ny-loc nuts. Also, selected 1.5" shoulder bolts - fewer threads cut equals stronger bolts. Using large diameter washers to help keep them from burying themselves into the plywood upon tightening. With the left offset from center, the washers on the left had to be ground a bit in order to fit between the mounting hole and engine box side wall. With an Exacto knife, I removed a washers worth of triangular stock so that the left top washer could slide between it and the firewall. Worked out well - was able to get a socket wrench on all the nuts without removing any of the triangular stock.


Still such a long way to go - but it feels good to have the engine in place!


Front View:


And, a problem....dang it. The muffler is hitting the bottom of the engine box. Now what?

Some options:

1. New muffler - maybe find one that fits better; the old muffler has a crack, which I've tried repairing with a weld stick, but its not holding
2. Modify the engine box - wonder if I can bevel that bottom edge and still maintain structural integrity?
3. Custom muffler - I do like the custom exhausts where builders have put the exhaust tips at full-scale locations.
4. Customize the existing muffler - its already cracked, why not cut it up and weld it back together?

Have a Village Workshop nearby (http://www.thevillageworkshop.com/) in Northville. I'll need to pay a visit there, for options 3 and 4. Lowering the engine is another option - currently the hub centerline of the engine is at the correct height per print. Would lowering it a quarter inch be a problem? Will need to check cowl fit - see if lowering the engine will cause it or the spark plug cap to hit the cowling or extend outside of it.

Any recommendations? Keep it scale location, hub centered in cowling and find a muffler solution - or just lower it?

Chad Veich

My Feedback: (60)

Instrument panel and gun sight shipped out yesterday Dale. The Hellcat is looking good. In regards to the muffler situation, due to the shape of the cowl, I am pretty sure you could get away with lowering the thrust line by a 1/4 of an inch without anybody being the wiser. Of course if it needs repaired anyway than whacking of the offending section and re-welding it may be just as simple of a solution.

DaleCS

Hi Chad,

Thanks - will keep eye open for shipment and post pictures ASAP.

I'm going to drop the engine. I've taped the cowling in place and found a couple things:

- The spark plug cap is already hitting the inside of the cowling - I'd need to put a clearance hole there already, whether I lower it or not; my Byron had the same 'feature'
- The center engine opening of the PCK/Don Smith cowling is a bit lower than the cowling shown on the Ziroli plan - I don't know which is correct to scale, but the PCK cowling is the one I have (though it will need a lot of rework to fit F1)

So, drop it I will. I figure then that I will have all muffler options open to me - reuse, reconstruct, purchase new or build custom with scale exhaust pipe tip placements.

I have two rework options:

- Plug the holes I drilled and start over.
- Remove the old engine box firewall and start fresh with a new piece of 3/4" ply.

Think I'll go ride my bike - beautiful Fall day, blue sky, leaves changing colors - maybe I'll have my decision by the time I get back......

DaleCS

Decided - plugged with hardwood dowel and sanded flush. After glue sets 24 hrs,, will remount with plate 1/4" lower. When it all looks good, will drill and peg thru the tops and sides.



Here are some shots showing the difference in the shape of F1 vs. the back of the PKC/Don Smith cowling. Lower sides need to come out and the top corners moved in. I need to contact PKC to see what kind of resin was used in its construction. Watching a number of auto restoration shows (Fantom Works, Overhaulin', etc.), have some ideas on how to make this work. As slow as I'm going, would rather have a cowling that fits, ready to go, but haven't found one yet to fit a Ziroli 1:6.

Chad Veich

My Feedback: (60)

I can't see exactly how much "nip and tuck" you need Dale but might it be easier to change the shape of the front of the fuselage rather than the cowl? Also, if you open up the cowl flaps for cooling then you will not have to worry about those areas mating up exactly. And note how the fuse "rolls" into the cowl in the flap areas as well.

http://svsm.org/gallery/f6f-5k/P1450056

DaleCS

Fuse roll - yes - thinking about that as both a means to hold the cowling in position, and as scale detail for when flaps open. .

Reshaping the fuse - yes, had thought of that, and with your comment, I'm rethinking this.

- The top quarters may not need much reshaping - once the sheeting is done on the top of the fuselage, I just may need to add a layer of sheeting and then sand to shape of cowling and flare into fuse.
- Side/Lower quarters of F1 need material removed.
- FWS-2A/F1A/FWS-2 ply fuse wall sides need to pulled in, too,
- The amount of pull-in required may mean that modifying F2 as well - which is a show stopper, as this would require pulling out wing mounting blocks in order to reduce their width
- The indent for the upper exhaust needs to b pull in, as well

I should have done the reshaping of F1 and F2 before beginning assembly....at the time, was thinking that keeping to the scale lines of the Ziroli plan was more important.

Still, will check. If I can reshape without getting into F2, I may go this route, now. I've cracked cowlings before and had to replace them. The idea of having to cut up and re-glass another cowling if/when this happens again is souring my thoughts.

Also, will check with IBM (Iron Bay Models) - maybe i'll get lucky and find someone in their office to return an email/call The Byron based cowling has more detail - would rather do the reshaping of the fuse using the Byron cowling, if I can get a couple. If I can't get a spare, then I'll stick with the PCK cowling on the idea that I can get another one, if/when needed.

Reshaping the wood will certainly avoid having to work with polyester (high VOC) resin, which sends my wife into instant headaches. Now that temp have drops, I can't be doing such work outside any longer.

DaleCS

Looking closer, I should be able to reshape F1 without having to cut into F2. The adjustment at the top of the exhaust indent is only about an 1/8". At the bottom of the indent, its about 1/4" - I think I can pull this in and blend/shape it without getting into F2. Will try to make contact with IBM. If this is a 'no go,' then will work with the PCK version - have an idea on how I can add the 'raised panel' feature that runs across the top of the fuse and cowling, as shown in the link picture that Chad provided, above. This feature was built into the IBM/Byron cowling.



Engine mounting plate back on, this morning, 1/4" lower:


Engine mounted - still need to make shim for 1.5 degree right thrust offset.


And, with necessary muffler clearance! All muffler options are now possible - but will take 'buying a custom Pitts-style' off the list - can use off the shelf, now.

DaleCS

Comparison of Chad's components, at top, to DB. I paid Chad for assembly and painting - well worth it. 3D printing is the way to go. Vacuum forming is adequate, given that when flying, no one sees the details. Expect as 3D printing prices drop, it will become the standard for prominent, detail pieces.


Chad even has the screws detailed:


Mark VIII sight and mount. Notice the two lenses, which appeared on some models:


Here, I hope you can see the third lens, on top of the site barrel - one can actually peer inside the body of the site!


Thanks, Chad!

DaleCS

In case anyone has an interest in the Byron Purr-Power exhaust – I have one, which needs some work:

1. I have all the components, including mounts
2. The exhaust header has been removed from the exhaust – one would need to replace the tube between the header and exhaust cylinder to make the whole assembly functional, again
3. I made this modification, as the PE 4.2 was running too hot (melted the dummy crankcase cover) and too slow (800 RPM low), though it sounded great! After removing the header, installed a Pitts-style muffler – the temperature dropped and the RPM came back (though the wonderful sound was lost). The exhaust cylinder then just served as an engine mount.
4. A smaller engine might run well on this setup, without the heat/RPM problems I had with the 4.2
5. Or, if one adds another exhaust port, one might increase the flow enough to run a 4.2 without the heat/RPM problems I had
6. The parts are sitting, now for some years, with no use – hate to send them to re-cycling.
7. Would consider best offer - at least cover shipping cost.

DaleCS

Jumping around a bit - started to work on the inboard flaps.

As the inboard flaps were aluminum covered, I'm building the flaps per print. I did check hinge location dimensions, left vs. right, and found that they are different, per print. The print, in some cases, is more of a guideline....

I used the measures from the left flap, transferring them to the right, rather than relying on the print. The offset hinge Robart hinge points and brass extensions are all per print - not scale. Decided against trying to replicate the mechs on the full scale. The Byron had similar hinges as shown on the Ziroli and it flew very well.

The innermost ribs aren't fixed in place. First, need to fit the flaps to the wing, then cut, fit, shape to fit the fuse, then apply the top sheeting. Then, I'll tackle the outboard flaps.

DaleCS

Alright, this doesn't look like much progress, but its the rough sanded last step of several.
- repositioned rear former of belly pan (built and sheeted the belly pan as part of fuse; when cut from fuse, the belly pan would not go back in; I've heard that wood is alive....)
- applied filler to body (water putty/light spackling mix)
- filled gap between ribs of center section at trailing edge
- fit filler blocks to TE of left and right ribs E2
- applied bottom sheeting to center wing section from TE to
- rough sanded top edges of belly pan to fit underside of wing

- then, finally, sanded fuse filler and wing filler blocks

With the wing filler blocks and fuse now blended, I can cut/shape the inboard edge of the inboard flaps to fit.

Filler blocks fitted


Body filler, wing filler blocks and belly pan rough sanded.



Iron Bay Models - Status Report: They're still doing business! They're currently not shipping kits, as they are in the process of moving from WV to PA. It took about a week, but they did respond to my email, indicating that they would contact me in January, regarding the purchase of an F6F fiberglass cowling.

I know that this is not the primary business of the owners - their primary business is with DOD. Iron Bay Models is more of a hobby, for them, keeping the Byron molds going. So, their customer service can be spotty, at best. Had they returned my calls and emails 2 years ago, I'd be flying my F6F, rather than still building it.

Oh, well - this has been a new challenge for me, still having fun.

DaleCS

Inboard flaps fitted to fuse, Ready for top-sheeting and mounting the hinges to the center section.



Because the flaps using offset hinges, a pinch point will develop as the flap rotates down, as shown, here:


The 'fuse filler block' that I installed in the wing center section was tack glued into position. After getting it sanded to blend with the fuse, I laid a piece of tape between the top and bottom trailing edges:


The edge of the tape forms a 'break' line. I removed the filler block, sanding it to remove the pinch point, the tape giving me a nice, clean line. Then, reinstalled the block. This picture highlights this break nicely, as the shadow in the leading edge area of the filler block is created by this break sanded into the block. End result: No flap impingement on fuse filler block.

DaleCS

Inboard flaps - sheeted and rough fit. Why rough fit? Ribs were scaled down to 1:6, but sheeting was not - so, the top sheeting is hitting the underside of the flap cutout, where print shows a small gap. Nothing a bit of sanding won't fix.




Now, to start on the outboard flaps. It was rather fun to make these sheeted inboard flaps - wouldn't mind doing the outboards in the same manner, per print, but this is how the Byron was done, too, and its not too scale. Want to do this differently, this time. Outboards were fabric covered, so I'll do the same, with idea that I can simulate the rocket exhaust gas protective sheeting, if I add rocket pods.

DaleCS

Outboard flap construction: Plans call for sheeted outboard flaps, and so there are only 5 ribs shown on the print, and provided in the short kit I had cut. From scale drawings, looked like fabric covered outboard flap had 15 ribs - so, 10 to cut, fit and shape.

Measured and positioned ribs per scale drawing. The tops of my ribs were roughly traced and cut using the outlines of the 5 ribs from the short kit, leaving enough material to sand them to correct shape after installation. Once installed, I wrapped a short piece of sand paper around a sanding bar. The sand paper rode on my rough cut ribs, taking material off, until the bare ends of the sanding bar came to rest on the tops of the short kit ribs.



I plan to install a bottom spar. The assembly is a bit floppy - if the bottom spar doesn't add enough rigidity to the flap, I think I'll sheet from the LE back to the top and bottom spars. Once "D" boxed, rigidity should be more than sufficient.

Later, same day: Bottom spar installed, bottom front sheet and bottom cap strips installed, inboard rib set to match dihedral angle of wing rib W6.



The bottom front sheeting helped, but I'll have to add the top front sheeting, complete the "D," to get the necessary torsional rigidity. Will do this after hinge points are installed.

Mpizpilot

My Feedback: (45)

Been following your thread as I'm building a Ziroli Hellcat as well. Your pictures of the inboard flaps were invaluable to me. My fuse is built and sheeted, stab and elevators done and I'm ready to start sheeting the bottom of the center section. Did you leave a gap in the sheeting at the flaps to help with cutting them free? Are you going with one servo per side for the flaps or adding a 2nd for the outboard section.

mirce

Hello, a lot of pictures of building Ziroli Hellcat you can find here...

http://www.nsmodelers.rs/warbirds/hellcat-novi-projekat

That was my second Ziroli F6F and all "mistake" from first I change on this second build.
I have about 100 flights without any problem before I sold it...

Regards

Mirce

DaleCS

Mpizpilot: Thank you - glad to hear that you are finding value in my posting/pictures. Check Mirce's postings, too, as some of the things I'm doing I picked up from him.

I cut my flap and aileron rib pieces from the wing before applying the top sheeting. I then built up the flaps and ailerons separately. I don't know if this is the best way to do this, but it worked for me.

Your approach sounds solid. I didn't even think of this method - since I was planning to design and build up fabric covered ailerons and out-board flaps, I just cut all the rib TE's off. Using your approach, leaving a gap sounds like a good idea.

With my approach, the previous posts show how I fit the flap to the center section and fuse. I forgot to add the picture shown, below. Here, I've added the center section bottom sheeting, but only enough to allow mounting of the balsa blocks for the hinge points.



In my 11-13-2016 post, the hinge points are laying across the bottom TE spar. I didn't get a picture of the next step, where once positioned, I cut slots for the hinge points through the trailing edge spar. I then applied the bottom sheeting. Next, I cut balsa blocks for the hinge points, cutting grooves in them using a scrap piece of the same brass tubing I used to make the hinge point extensions. When done, I had hinge point mounting blocks with grooves that matched the hinge point extensions diameter, that I could then glue into position on the top side of the bottom sheeting.

No drilling required. Perfectly aligned hinges. Had I sheeted the entire center section, I would not have been able to do this. The outer hinge point mounting block could be positioned through the wheel well opening, but the inner hinge point is boxed in, no access.

Servos: Haven't decided, yet, whether to go with 2 or 4. I'm leaning toward 4. Used 2 on the Byron - it had the same setup as the Ziroli with the outer flap driven by a pin between the inner and outer flaps. Worked fine, flew beautifully on landings, no issues and no one ever commented on that pin. But I see the pictures of the full-scale Hellcat, flaps deployed - there's no pin! It just looks a heck of a lot better without that flap pin. Since I don't have the actual Hellcat flap mechanism, seems like the least I can do is get rid of that pin....

I've ordered some offset hinges from Tamjet for the ailerons, and have sketched up patterns for the inner- and outermost aileron ribs. Now waiting for hinges to arrive to confirm hinge point location before cutting anything. If my assumptions are wrong, I'll need to modify the leading edges of my design in order to ensure that I have enough clearance to get the minimum throws necessary.

While waiting for parts, have started on the right outboard flap.

Let me know what you decide to do on your flaps and how it works out.

Added content: Please, go back to the flap mounting section above. I'm adding a few pictures there regarding a detail regarding the 'fuse filler block' - because I'm using offset hinges, a pinch point can develop as the flap lowers.

DaleCS

Mirce: I took my plane out our giant scale fun-fly event. It was raining, so, it stayed in my vehicle. But another builder their wanted to see it as he is ordering a short kit for the Ziroli Hellcat. He really liked your idea for air cylinder placement, and is having his cutter include this in the design.

Passing his thanks on to you!

Mpizpilot

My Feedback: (45)

I think I pretty much ended up with the same results as you, inboard flaps are mostly complete. LE flap sheeting is also hitting the underside of the wing trailing edge.

I see see you built some extra support around the hinge tubes, has there been concern with mounting them the way the drawings show?

Im interested to see your offset hinges for the ailerons when you get them.

mirce

Thank you...

My idea during building was to putt all parts as far forward as possible...

Regards

Mirce

DaleCS

Regarding the additional support for the hinge points: I know of no problems, but if the drawing proves insufficient, its a major tear up to open components after they're sheeted, glassed, painted and mounted.

By making up my 'hinge point blocks' when using hinge points I believe I get a few benefits:

1 - I can ensure better alignment of hinges both before and during glue-up. During gluing, the hinges are in guides, their full length - I won't come back after the glue has set and find that anything has shifted.

2 - I can leave the parts separated until glass and paint are completed, and still be confident they will go together in perfect alignment with sufficient glue coverage.

3 - I can test fit and alignment easier, not just flap to wing, but also fit to fuse, as there is something there to hold the hinge points in place before they are glued.

One thing I noticed in your picture is that you've built the flaps per print. When you assemble the wing to the fuse and attach the belly pan, you'll find that the inner ribs of the flaps, at their LE, are actually inside the fuse. The TE of W2 may be flush with your fuse, but the fuse/belly pan are curved, they get wider as you move toward the front of the plane - they extend outward over W2 over the flap LE.

In the up position, this is fine - the LE edge of the flap tucks up under the fuse side.

However, you'll find interference when lowering the flap - it will hit the belly pan on its way down!

The full-scale Hellcat wasn't like this. 760aaron62 posted some pics on this thread (5-18-2016) showing a smooth fuse at the flap interface, there are no cutouts in the fuse for the flap to rotate into.

The drawing is wrong.

Mpizpilot

My Feedback: (45)

Great! Lol.

I had had to bolt up the wing to fuse and check what you are talking about. You couldn't be more right. Oh well, I'll figure something out.

DaleCS

Well, that's half the fun of building from plans without instructions! Nice to have forums like this where ideas and pictures can be shared, questions asked and other eyes can take a look at what one is building.

Noted your location on Long Island. You're right in the middle of Grumman history!


Tamjet offset flap/aileron hinges arrived, today. There's a small and large offering - I ordered the large, and these look perfect for the application.


Now, they have just a simple through hole, no swivel ball. This means the hinges will be mounted as shown in sketch A. Whereas the full scale Hellcat has them mounted as in sketch B.


Will call mounting shown in sketch A good enough. Main goal is to get the added drag induced at low speeds, high deflections, by having the LE dip below the wing with the aileron raised, to counter adverse yaw, same as the full scale Hellcat. These hinges have the scale-like appearance - gets me close enough. If I were building a museum or competition piece, I guess I'd have to make my own hinges, as I don't see anything available that will let me mount them as in sketch B.

Hope to get some work down tomorrow. Today, cleaned up last of leaves, put the lawn tractor away and got the snow blower out and started. Had a beautiful Fall, here in SE Michigan. Last 3 years, I was able to ski on my hill before Thanksgiving Day. This year, still biking and cleaning up leaf fall into December.