butlern

My Feedback: (15)

Yesterday afternoon I was able to get around to permanently joining the center sections together.

The first step involved attching the outer panels and then dry-fitting the two center sections to check the fit of the pywood spades. In addition, and even though the dihedral angle is pre-cut into the two center section halves, you have to check to make sure that the mating surfaces fit together perfectly. To do this, the wing tips were blocked up to set the tip height at 4 inches. Since I don't have a 10 foot building table, I had to do all of this on the floor, so extra care was taken to make sure that carpet didn't confound my measurements. The center section joint sits atop a piece of mirrored glass that I have laid on the floor. Once the fit was verified, the two halves were epoxied together. The oversized plywood spades were not glued at this time, as they were only in place temporarily to verify alignment. Some tape was also used to keep the two halves pulled together gently and evenly.

Once the epoxy set, the outer panels were removed and the plywood spades were marked along the upper and lower surfaces of the wing, trimmed and sanded and then it was all put back together so that the spades (now trimmed to match the upper and lower contours of the wing) could be permanently glued into place. AS per Jeff Q's suggestion, a few holes were drilled into the front and rear spades so that the polyurethane glue would form natural rivets and better hold the wood and foam together.

So that was that. Now it's onto final finishing of the foam to get it ready for sheeting. There are two places where the wire "scarffed" the foam a little bit during the hot-wire cutting (visible just behind the firewall attachment point on either side). Very, very minor, but these low spots will be filled because the wing surfaces should be as perfectly smooth as possible before sheeting. I will use a very thin layer of lightweight spakle to fill those two low spots.

A little bit closer to finally sheeting the wing. 116 inches, exactly!

Back soon.

Noah

butlern

My Feedback: (15)

Another quick update. First, I found some photos of the stab sheeting so I thought I would post them here. I followed the recommended approach that Jim outlines in the instructions. Very slick! The stab was sheeted using 4 seperate pieces of 1/64th ply. Each ply piece was first trimmed a bit oversized and then dry-fitted to make sure it would lay down OK. Then glue (I'm using West System epoxy to sheet the foam) was spead over the bottom, left side of the foam core and the inner surface of the ply sheeting that covers this side. Next, a thin bead of odorless CA was run along the edge of the sheeting where it overlaps the leading edge balsa. Then some "kicker" was brushed (not sprayed) along the leading edge balsa itself.

Once all was ready, the leading edge of the sheeting was CAREFULLY positioned along the leading edge balsa. As soon as it touches, it's down for good. The rest of the sheeting (with all the epoxy) was then just pressed onto the foam surface. The core was flipped and the process was repeated for the top, left surface. Once both top and bottom of the left side of the core had sheeting in place, the part was placed back into the shuck and ~40 lbs of weight was applied to press everthing together and force the epoxy to fill all the voids. I just repeated this process for the right side of the stab the following day.

I really liked how easy this method is, and it's really slick how the CA'd portion of the sheeting holds it nicely in place while the part is positioned in the shucks for weighting.

Anyway, I did this several weeks ago, but I finally got around to trimming back the sheeting that overlapped the trailing edge so I thought I'd snap another couple of pictures. All that is left to do fill the "step" where the sheeting overlaps the leading edge and tips with a little light weight spackle, shaped the leading edge and tips and then fiberglass.

butlern

My Feedback: (15)

The only real work I have done since last week has been the capping of the wing roots. I deviated from the instructions (again), so I have not yet had a chance to finish prepping the wing panels for sheeting. I'd hoped to start sheeting the wing panels this weekend, but..... Next weekend for sure.

Anyway, my deviation: the instructions call for capping the wing roots after the sheeting is applied, but I decided to cap first then sheet the surface. My thought was that the sheeting would look more "finished" if I overlapped the caps, rather than the other way around.

So, I just used some 3/32 balsa for this. First I measured the location of the joiner stubs, and then transferred those marks to the balsa. Once the holes were in the balsa, I slipped the oversized caps into place and the glue permanently. Rather than sand the caps flush with the wing contours, I rough-trimmed the caps, leaving about 1/8 of an inch excess. I then went on to do the same for the center section caps.

The reason I left the excess is because it will be much easier to sand accurately AFTER the outer panels are bolted to the center section. Once it all assembled, running a sanding bar across the outer panel and center section panel really makes it clear where the low spots are located. The caps also help make filling in with light weight spackle easier, too. Now that the panels have been sanded together, all I have to do is fill the low spots with spacke up to the sanded root cap balsa. Now both top and bottom wing surfaces will meet perfectly after sheeting.

butlern

My Feedback: (15)

Alright, that's it for now.

Will try to get some of the main wing sheeted this coming weekend.

I'm actually almost dreading bring the fuse into the house... this plane is huge and I have a such limited work area! I can barely get 2/3 of the wing to stand on end in my "shop."

Be back soon.

Noah

butlern

My Feedback: (15)

Laudy,

If you're still checking here, can you provide some details on the elevator servo installation? Where did Rich and Mike mount the servos, in the tail under the stab? Pictures would be great, too, if you're able.

Thanks,

Noah

butlern

My Feedback: (15)

Finally managed to get some of the wing sheeted. Before sheeting, the location and measurements of all servo bays, spars, servo wire tunnels, etc. were noted so I could find them again after they all get covered. I started with the outer panels. The 1/64th ply sheeting comes in 4x4 foot sheets, so the pieces for the outer panels and center section were first cut from the larger sheets. The foam was carefully checked for low spots and dents, and any imperfections were filled with light weight spackle.

After the spackle was dry and the panel was sanded smooth, epoxy was applied to the bottom of the foam core and the inner surface of the ply sheeting. All excess epoxy was scraped off with a playing card, so there should be just enough epoxy there to hold everything together tightly without adding too much extra weight. As I did for the stab, the sheeting was held in place by applying foam-safe CA on the leading edge. Once the leading edge was down, the rest of the sheeting was pressed into place and the core was placed in the shuck. The core was flipped and the process was repeated for the top sheeting. After both top and bottom sheeting were in place, the cores were weighted in their shucks and left to cure for 24 hrs (stainless sculptures help with the needed weight).

So now the two outer panels are finished. Just need to shape the tips and the leading edges

butlern

My Feedback: (15)

Still working on the center section this weekend. I have the left side sheeted, it's under weight right now, and I'll get the right side finished tomorrow.

The center section sheeting process has been the same as for the outer panels, except I had to do some careful trimming of the sheeting where the left and right sides meet in the center. The camber/airfoil requires that the sheeting be shaped so that the left and right meet tightly in the center (concave edges that meet on the upper surfaces, convex edges that meet on the lower surface of the wing).

So, once again, much of this work only takes 30 minutes to an hour to complete, but I have not had much time to spend on the plane these past few weeks... and now I'm once again sitting around waiting for the epoxy to cure!

Will be in touch again soon, hopefully with a sanded wing and a good start on the installation of the firewalls/nacelles.

regards,

Noah

butlern

My Feedback: (15)

Just got the right side of the center section sheeted.

But before I started that, I first cleaned up the left half by trimming of the excess sheeting that overhangs the flap cutouts. Sharp hobby knife and straight edge and done.

Next, I started to transfer some of the locations from under the sheeting to the top of the sheeting. I marked all the spars (specially on the bottom if I choose to tie in the landing gear mounts to the spars), center section plywood joiners, and servo wire tunnels. I also marked where the holes need to be drilled to accept the wing joiner set-screws. I basically marked everything, because you never know when you're going to need that info.

butlern

My Feedback: (15)

Half way there...

The right side is weighted in the shucks for today/tonight. Everything was done (and will be done) to the right side just as I outlined above for the left.

If I can get some time early this week, I'll get the edges shaped and then move onto installing the firewalls and gear mounts.

I am hoping to get the wing and stab attached to the fuse before I set this aside and get back to the Avenger. A friend of mine offered his paint booth so I can finish up the primer/lines/rivets on the Avenger soon.

Spring is coming and the Avenger will be my priority!

Back soon.

Noah

butlern

My Feedback: (15)

Wing sheeting complete, including the horizontal stab.

The stab leading edge and tips have been shaped, and I will try to get most of the main wing shaped tonight... and then soon get a start on the installation of the firewalls/landing gear mounts.

butlern

My Feedback: (15)

Got the wing shaped.

Next step was going to be in the installation of the firewalls and gear mounts followed by the nacelles, but I ran into a bit of a problem. The main load-bearing former that supports the gear is supposed to be sunk into the foam wing, but according to the parts I have (the supplied plywood trusses and gear rails), the main former would end up located right where one of the servo wire tunnels passes across the bottom surface of the wing. Not good. Cannot lock the former into foam when there is very little foam there, and I also cannot block access through the servo wire tunnel because the wing is now fully sheeted and there's no way to make a new tunnel.

Well, long story short, I emailed to Rich Jennings (the guy who actually built the wing for the F7F reviewed in the HighFlight magazine) and he replied quickly. Rich stated that he and Mike also had the same issue, which is the main reason that they re-designed the gear mounts for their F7F. Rich still has the pattern and he very generously agreed to send them to me so I could save some time and simply adopt their fix to this problem. Jim Oosterhuis (from Giant Scale Twins) is also aware of these recent issues and is addressing this problem (that apparently popped up during the most recent run of F7F kits).

So, I'm currently awaiting the patterns from Rich Jennings before I get into the nacelles/firewalls/gear.

In the meantime, I moved onto fitting the center section to the fuse. Got the mold release agent washed off the glass parts the other day. Still very cold here, so I did this inside... Another move that deeply impressed my wife (me in the shower with a 102" long fiberglass fuse).

Anyway, in order to start fitting, the leading edge of the center section had to be notched 5/8 inch, and the trailing edge also had to be notched so that the wing would fit properly in the saddle. Very simple work. The leading edge will be secured via 2 5/8 inch hardwood dowels that passed through the bulkhead installed in the fuse and all the way through the balsa leading edge and into the foam. I am going to further reinforce this area by deepening the leading edge notch by another 1/4 inch so that I can epoxy in a piece of 1/4 inch AC plywood. I hate the idea of the dowels just getting buried in the foam and only passing through a little bit of leading edge balsa. The 1/4 ply plate that I will install should go a long way towards making the whole installation more durable. I still have to install the plate in the leading edge, so pictures to follow soon.

For the trailing edge, a ply plate will be glued to the upper surface of the wing and 1/4x20 bolts will pass through the plate, through the wing, and eventually into some blind nuts that will be sunk into the wing plate that comes pre-installed in the fuse.

Aside from the weirdness associated with the gear mounts, it's all coming together well. If I get the wing fitted before I get the patterns from Rich, I'll move onto dry-fitting the horizontal stab.

While I was dry fitting the center section, I could not pass up the opportunity to put on the wing tips to get a feel for the size of the model. The pictures do not do this kit justice. It's huge.

Noah

Thunderbolt47

My Feedback: (8)

Looking great Noah.

I almost bought one of these kits but backed out because of a lack of building experience. Maybe one day.
Kelly,

butlern

My Feedback: (15)

Thanks, Kelly.

I've been watching your Taylor Spitfire completion... I think you have the skills! Your Spitfire is looking great.

I was hesistant to get into building for a long time. For the first 4 years of my 7 year involvement of RC, I only assembled ARFs because I doubted that I had the skills or knowledge to build something myself. One day I just told myself, these models are nothing more than plywood, balsa, foam and fiberglass... it's not like anything is really permanent. If something isn't right, just cut into it and fix it! Obviously there are certain steps that require some thought and careful plasnning (in order for the fuse or wing to be straight and true, for example), but when working from plans or instructions, you just follow the guidlines in the proper sequence. Easy! The other important thing to remember is that help (from resources like RCU or RC Scalebuilder) are always available, and help from the designer should be available (that obviously depends, of course). So, there are huge numbers of people out there to call on for help.

Trust yourself... that's the only way to make that dream project become a reality. And never be shy about asking for help.

Rich Jennings emailed me a short while ago. He's forwarding the patterns for his modified gear mounts so I should be able to get those parts cut (and hopefully installed) this weekend.

This is likely the last week that I'll spend on the F7F for a while. Getting back on the Avenger soon. Need to focus on finishing the Avenger before I end up with two monster projects sitting unfinished in my basement!

Noah

at-6 texan

Hi Bulter you could tell me what kind of wood you used to coat for the wings?
thk!

butlern

My Feedback: (15)

All flying surfaces are covered with 1/64th inch thick birch plywood.

at-6 texan

ok many thk for response.
how much is an 1/64 inch.... is 3,9mm?

butlern

My Feedback: (15)

Hi Texan,

Sorry... 1/64th inch is very close to 0,4mm

G-Pete

Her Sam - for future references...(save the pic and print it)

jeffie8696

Shoot me a message when you get it to the field Iwanna see.

butlern

My Feedback: (15)

Jeffie8696,

I see you're from nearby Muscatine. Have we met? Did I meet you at the Aerohawks Swap Meet a few weeks ago?

The maiden (if it happens this summer) will likely take place at the Tipton, IA airport.

I'll give notice in this thread when the F7F is going to slip the surly bonds (of Earth, not the epoxy holding it together... but then again, you never know!).

Finished with the plywood reinforcment at the leading edge of the wing. Again, 5/8 hardwood dowels will get epoxied in the leading edge and will protrude into the bulkhead installed in the fuse.

I also trimmed away all the plywood sheeting that covered the servo bays. The servos will be mounted to 3/32 AC plywood and the ply will get screwed into the blocks epoxied in the wing foam (blocks detailed in an earlier post). The servo/plate shown in the pictures is from my Kellogg Avenger, but I just placed it in frame so my chosen wing servo installation method is clear.

Rich got the patterns for the modified gear mounts to me yesterday, so I'm going to spend some time this weekend cutting and fitting the gear mounts.

Back soon.

Noah

at-6 texan

Hi Pete many thk! for the conversion chart to inch at metric misure..that is very useful for me..thk again!

F4u5

My Feedback: (81)

Looking good Noah. Did the kit call for ply wing sheeting? My old mod-air was balsa sheeted. Keep chuggin'

Jeff

butlern

My Feedback: (15)

Jeff,

Yes the current version of the kit supplied by Giant Scale Twins calls for (and comes with) the 1/64th ply for sheeting. Although there may be a weight penalty... the wing and stab are like surfboards. Very strong and very rigid.

I think that I'll be lucky if I come in at less than 60 lbs.

Working on the gear thhis morning. Hopefully some progress to show by the end of the day.

Noah

jeffie8696

Its me Aerohawk Jeff. Bruce is my teacher. If it ever warms up .
Ihave at least 3 planes ready to go right now. My Avistar trainer, my Kadet trainer and my Mustang .20. Ijust installed an Aviastar 53 in the Avastar.
Not sure if Ilike the way the colors on the Mustang turned out, might have to recover it.

butlern

My Feedback: (15)

Oh!! Sorry about that, Jeff. I'd forgotten that you live in Muscatine. Bruce is a fantastic instructor, and he'll get you flying independently (and safely!) in no time this spring.

I'll be sure to let you know when it takes flight... I'm sure it'll be quite the event, wherever the maiden takes place.

I'll talk to you soon.

Noah