Harmony Aero Bridge Arch Top c 1930s. This is a spectacular little guitar.   It’s a rare round holed arch top mahogany and spruce acoustic guitar with the Aero bridge.  It is full restored and plays beautifully!
In the 1920s, multi-instrumentalist Roy Smeck was the 'Wizard of the Strings', extremely popular, and signed to an endorsement deal with Harmony to market the Vitatone line of instruments. These instruments featured the unique aero bridge. The purpose of the new bridge was to provide more gluing surface, thereby creating a solid connection between bridge and top, producing better tone. Whether that tone was realized is debatable, but one thing is certain, the guitars produced in that run of a few years are surely the aesthetic zenith of Harmony instruments. While some folks have indicated that these were in honor of the Lindberg flight across the Atlantic, recent research has shown that the first models of this guitar were advertised before the Lindberg crossing took place. It should be noted that there was a 25,000 prize being offered and there were several contenders attempting to cross the Atlantic by plane at that time so it was already a well publicized event and it was at the height of the airplane craze.
This particular round-hole archtop acoustic has not shown up in a catalog entry for the model that I have seen though I have seen several other examples. One source claimed is was a model v2148 which might reflect  the Vivatone name. It is among the most eye-pleasing of the Harmony line. The back and sides are mahogany. The top is a high grade of spruce. Both back and top are heat-pressed into an arch and left unbraced. This made for a beautiful tone, but ultimately proved to be the downfall of this instrument. The bridge is rosewood and profiled to reflect an airplane of the period (thus the Aero Bridge name). The neck is mahogany with a dyed maple fingerboard. The board exhibits multiple fancy pearl position markers. The head stock is overlaid in Brazilian veneer. The tuners are a fancier grade than stock tuners. The back, top are bound in w/b/w celluloid binding and sound hole is bound in b/w/b/w binding. The fingerboard is bound in white celluloid and is not the original binding. The top, back, neck and head stock veneer are finished in a handsome tobacco sunburst finish. All these details add up to an understatedly beautiful guitar.
 
The lower bout measures 14 1/2" across at the widest. Scale length is 25 1/4". The neck is carved in a very comfortable soft 'V', measuring 1 7/8" across at the nut and 2 1/4" across at the saddle.  
WORK DONE:
This guitar was in extremely bad condition when I got it. The top had not only collapsed, it went concave! This guitar only had cloth strip re-enforcements inside the body even though it had a through the top pin bridge. The back had a serious split, the top was coming loose and had collapsed down into the guitar, the neck needed a re-set.  The fingerboard was split and missing about 1/2 the inlays, the bridge was pulling loose.  It was one hot mess!
Harmony had made these in the 1920s and 30s.  They tend to be decent instruments, with some rather nice quality with fancy inlays. This one lacks some of the bling I’ve seen on a few of these, but it’s actually a very nice example of one of more obscure versions of this guitar; a rare round hole arch top guitar. It still has the original tuners, nut, frets, fingerboard (dyed maple), rosewood bridge, and pickguard. It features solid mahogany back and sides, spruce top, a rosewood “aero bridge”. It was missing the end pin which I replaced with an appropriate period piece from my collection of parts.
 
The first step was to remove the neck. The fingerboard is dyed maple and is quite brittle, but still usable so I was particularly careful taking the extension off. It was too brittle, however, to consider removing the fingerboard and inlaying a carbon fiber rod as I would normally do. It had one large split, and multiple smaller splits but I filled them all with ebony dust and superglue. With the neck removed, I took off the top since it was already loose and that is where I was going to do a great deal of the work.
 
There were cloth strips across the top and the back to act as re-enforcement, but there had never been any bracing of any kind. This was a very strange arrangement but makes for a surprisingly open, rich sounding guitar. It was clear, though, that the top had been gently arched and the back still was.  The top had completely collapsed inward and was actually concave when I first got the guitar.   
 
Once I had the top apart, I placed it on a curved sanding surface (on wax paper) then gently weighted it down to re-establish the arch. I let it sit for several weeks, gradually rep-arranging the weights to get the arch correct.  I glued the back crack and splinted a section where the wood was missing.  Once the back was correct again, I used a radius tool to copy the back arch onto a series of braces I cut to stabilize the top and the back and then glued them up. I chose to make three braces for the top and three braces for the back. I made them fairly tall, but only 1/4” wide to maximize strength but not kill tone, each shaped to the copied arch profile from the back.
 
I had to remove the already loose bridge to work on the top. Once the braces were installed, I re-glued the top. and was pleasantly surprised to find that it glued back on quite nicely. A rare treat!  I then re-set the neck angle and re-glued the neck. I re-bound the neck, replaced the fret I removed to loosen the neck, and leveled the frets.
 
The next big issue was finish touch up,  Over the years, the finish had been damaged enough that there were splits, chips and uneven places so after leveling the damage, I decided to do a light french polish overlay to smooth out, seal and protect the guitar. The finish turned out to be quite nice.  
 
The guitar was string up with John Pearse, Slightly Light (11-50) phosphor bronze strings and is just settling in now. Initial observations show a bit more bow in the neck than I’d like, but I was unable to remove the fingerboard due to it’s brittle nature. I would have normally inlaid a carbon fiber rod to straighten that out. However, after stringing up the guitar to tension and playing it for a couple days to let everything settle in, I was able to level out the frets again and eliminate the string buzz and get it to play clean. 
 
The guitar is light in weight, plays easily and produces a melodic, airy tone, full and rich with excellent sustain, skewing more toward the sound of a flat top as opposed to an archtop. The V neck is surprisingly comfortable to play. A great finger picking guitar.