Balsa Build Along 2017/18 - Hobbico 300S, Thinning the Herd

[Joker 53150]

Still feeling pretty cruddy and running at about 1/2 speed, but that didn't slow me down from hitting the swap meet in Manitowoc, WI this year. Yes, the place from "Making a Murderer" on Netflix. I figured as long as I stayed out of the junkyards I'd be safe!

I was hoping to find a good engine for the Extra 300S, and ended up finding a couple good candidates. In the end, I picked up an OS .61 glow engine which appears to have very little run-time on it. The seller said it's only been bench-run, but it seems everybody selling an engine only "tested" it... For $50 it was worth a shot as they normally go for more than that used online, and this one was clean with good compression and a smooth carb action. Another guy was selling the adjustable engine mount it's sitting on for $1.00




Most of the swap meets around here also include at least 1 vendor who sells all kinds of little bits & pieces needed for the hobby, from servo extension wires to servo testers, and fuel filters to glue. The guy who hits most of the swap meets near me usually has a good selection at reasonable prices (it's all NEW stuff), so I like to pick up whatever strikes my fancy to thank him for attending the event. This time I got some parts that will be needed for the Extra - a fuel filter, exhaust extension, power switch with LED, clamps, fuel dot, etc. His prices are usually a little cheaper than Tower, which is a nice bonus.




Now that I've got the engine I'll need to get a cowl ASAP so I can work out the mounting location on the firewall. The previous owner had mounted T-Nuts on the firewall for an engine, but that won't fit my needs.

For those who haven't attended swap meets before, you should really consider it! The deals can be amazing, such as a plane my buddy picked up while we were there (the same guy I did the Arrow trainer re-build for). He picked up a high-wing glow trainer (I forget which name brand, but very similar to the Arrow he's already got) - it came with an OS .40 glow engine, FM radio, and the plane was in very good shape with only minor hangar rash. $60...! He doesn't need the radio and it'll probably be given away or sold dirt cheap, but the engine alone on that plane is worth $45-ish. If I would have saw it first it would have been mine!

 

[nhk750]

For those who haven't attended swap meets before, you should really consider it! The deals can be amazing, such as a plane my buddy picked up while we were there (the same guy I did the Arrow trainer re-build for).

I am amazed that we here in the Seattle area don't have a larger RC airplane presence in the world with Boeing being here and year around flying available. So, we don't have any swap meets that I know of and I am not even sure how to find one if we do have one. I know there is a yearly AMA booth show in the spring and that is about it. You would think it would be a boom town for RC here with Millions living in the area now, but?

 

[Joker 53150]

Here is one next weekend south of Seattle, https://rcsouthsound.com

 

[nhk750]

Here is one next weekend south of Seattle, https://rcsouthsound.com

Wow, thanks. There is hope for us in Seattle...

 

[Joker 53150]

Hey, it's November 1 and I can finally start the build!

The latest work is centered on getting the servo tray ready for servos and the wing mounted. The servo tray was already installed, but the builder didn't bother adding the bracing (Popsicle sticks) called for in the manual. I epoxied them in place on top & bottom of the tray for strength, and then added the T-nuts for the wing bolts (not shown in this pic). Lucky for me, most of these pieces came with the planes so I didn't have to do much fabrication!




While that epoxy cured I prepped the wing for the mounting bolts. It required adding a ply strip across the center of the trailing edge, and lucky for me that piece was included, salvaged off a previous kit as it had some old bits of glue on it. I really like the idea of using as much old/original material as possible so I cleaned it up and stuck it in place. The bolts (shown) go through the wing and down into T-nuts mounted in the fuselage. Some additional fabrication work will be needed to build some structure across the rear of the wing area shown here, and then a large plastic cover will be cut to size that will fill in the entire area below the wing. That piece, the cowl, and the canopy account for just about everything that isn't exposed balsa on this plane!




I'm also prepping for the tailwheel installation, and going a different route than called for in the manual. The plans call for a simple bent wire design that connects to the rudder. It works, but it's fairly light-duty and just looks lame, so I'm going with a fuselage-mounted tailwheel that is much stronger and looks better. It'll give me a weight penalty at the tail, but I can live with that!

 

[Joker 53150]

Oh, and the wheels have now also been swapped out for new (to me) DuBro soft low bounce type wheels. The original are a bit too small and are very hard plastic which would provide a fairly rough ride. The replacements were new in the package for $3 at the recent swap meet. I’ll also try and use some nice fiberglass wheel covers that set me back another $1.50.

 

[Joker 53150]

With the tailwheel installed she's sitting on her own feet for the first time! I just need to push the distractions off to the side for a while so some big work can get done on it. Weather was decent-ish yesterday so I took the day off to head to my dad's place to fly for what might be the last time this season. Then both flight boxes needed to be organized and cleaned out, all batteries put into storage charge, etc. Distractions!




This is one of the wheel covers I got at the swap meet, which might be installed on this plane. The price was right at $1.50 (if I remember correctly, they might have been $3.00, which would still be a great price for fiberglass wheel covers).




The trailing edge of the wing has a support structure which will hold the bottom faring. The front and rear pieces were not included with the kits so I had no pattern to work from. The initial fabrication was done slightly over-sized so I could then sand as needed to achieve a good fit.




Those front and rear structures are what this plastic faring will attach to. Eventually. The pieces still need a little sanding so the sides of the faring sit flat on the wing. The wing will also get fiberglassed before the final installation, and I'm planning to use epoxy and micro-balloons to get me a smooth transition. When installed, this piece will lift off with the wing.

 

[Joker 53150]

I'm making a few changes as work continues on this plane. First: the elevators. The stock configuration called for separate elevator surfaces with dual pushrods, a plan that has it's merits. Since the elevators aren't too large I'm making a change and connecting them with a hardwood dowel so a single pushrod can control both. It's a little simpler design with less components to fail (hopefully). The elevator construction will still be like the original, made from a built-up balsa framework that is sheeted with 1/16" balsa on top & bottom. Cutting the hinge slots will be the biggest problem, thanks to the hardwood pieces I incorporated into the design!

I'm also re-thinking my original plan for finishing the plane. The initial idea was to fiberglass the entire plane with finishing epoxy, and then add some simple graphics or ghost-painting over the natural balsa finish to show off the wood. While I still think it would look fantastic there is growing concern about overall weight of this method compared to simply covering it with Monokote (or similar). Both ideas are on the table right now, but it's getting close to the time where a final choice needs to be made!

 

[jsknockoff]

I think the natural finish would look really great, but if you go that route I would build the bottom wing cover and cowl out of balsa. Only way around an unfinished look would be to use the plastic parts and paint some sort of trim design to cover those areas.

 

[Joker 53150]

Those areas were bugging me a bit, but not enough to warrant constructing them from scratch! The belly cover wouldn't be too difficult, but making the appropriate cowl would be more work than I want to take on, plus the fiberglass cowl has already been ordered.

A couple ideas with the "natural" finish - the plastic belly pan and fiberglass cowl & wheel pants are-what-they-are, and the natural finish is simply peeking behind the curtain to show how the plane is built. Or those items could be painted somehow in a manner that ties finished and natural finishes together.

The big concern with the natural finish is how big the weight penalty may be - fiberglass cloth, finishing resin, and some paint all add up quickly compared to traditional covering. Some have suggested using a clear Monokote, but I'm not sold on that idea as it doesn't "enhance" the balsa's look like the epoxy covering would.

 

[Joker 53150]

...and I just got notified that Fiberglass Specialties has shipped my cowl! Can't wait, that's been keeping me from installing the motor mounts as I need to make sure it's lined up properly. Hopefully the muffler fits without too much work, but I'm guessing that a bit of material will need to be removed from the firewall. Unless I go with a Pitts Style muffler, but those run $50 or so, and I'd rather not spend that much if I can avoid it.

 

[nhk750]

Nice, I have a Fiberglass Specialties cowl for my Hog Bipe build also. I am almost ready to join the fuse sides then I can see how the cowl fits.

 

[roversgonemad]

How long did it take from order to shipment? I am still in the air on what I'm building, and my RCM Agwagon is pretty high on the list. I was going to order the cowl and the Hoerner wing tips.

 

[Joker 53150]

Mine shipped in less than 2 weeks. My guess is that they had to make it, as I can't imagine the Hobbico Extra 300S is so popular they keep it in stock. I recall the lead time for the huge cowl for my L-19 Bird Dog was also about 2 weeks lead time.

They do a good job with quality, and my L-19 cowl also included instructions on cutting/trimming it, cleaning and prepping it for paint, etc.

 

[nhk750]

Got my cowl in less than two weeks and good quality too.

 

[Joker 53150]

Most of the elevator work is done. Here's the basic design, based on how the originals were made but with the extra hardwood added to connect both sides together. Not knowing which side I'd end up attaching the pushrod to I added ply on both sides (the large triangle near the center). As with the rudder, I made the elevators slightly over-size so I could do final sanding later on to even it all out.




And here you can see what I mean by making the pieces slightly over-sized. Plenty of sanding is still needed to finalize the shape, but it's coming together nicely.

 

[Joker 53150]

The cowl arrived today, well packed and in great shape from Fiberglass Specialties. However... it looks quite a bit longer than I expected!? Even with the .61 glow motor mounted as far forward on the mount as possible it may not be far enough to get the prop outside of the cowl. The more I look at it, the more it looks like it needs to be trimmed a bit, which would be fairly easy to do. I'll need to review pics of the actual plane and pics of the RC version and come up with a plan. At first glance it appears that about 2-1/2" could be trimmed off, which would put the prop in about the right spot. More to come!

 

[jsknockoff]

Apparently they sent you the magnum cowl!

 

[Joker 53150]

They saw my name and figured a Magnum was appropriate!

A little trimming and it fits much better. 1-1/2" was taken off all the way around, and once the motor mounts are installed I'll be able to do some final tweaking to get just enough of the prop shaft out of the cowl for good spinner clearance. There is still a little extra space all the way around, but that'll help with cooling airflow. Some spacers will be cut to make sure the gap is even around the perimeter. With the little bit of canopy I have set in place it's really starting to look like an airplane!

 

[jsknockoff]

I’ve always liked the looks of the Extra style planes but never got into the 3D thing.

Joker, you and I may have to start on a second build off project at our current rate.