SP-500 – 2,700cc – Spencer Gould

Friends:

This letter and photos came in from Spencer Gould. Some quick notes on his background are in a letter he wrote in the “Mail Sack – Stromberg” story.  If you have one of our Zenith Install Manuals, his picture is right up front in the introduction as one of my Hangar Gang. In that paragraph I am pointing out that many experimental aviation companies are staffed by polo-shirt-clad salespeople while our crew has always been 100% hard-core aircraft builders. Spencer was my key guy for the CAD work that went into our 5th bearing and many of the Gold System Parts. He is no Troglodyte, he is an intensely driven very smart guy The design you see here was actually flight tested in a 1/4 scale RC model. Spencer flew it with a live video downlink in the plane focused on the left wing, which was tuff tested to look at the airflow pattern over it. Every layup in the plane has a structural calculation associated with it, nothing is eyeballed. The SP-500 is not your average homebuilt.-ww 

(Note: Being a Troglodyte, I am not very good at posting pictures, and if the pictures take a while to load, it’s probably my fault, and I will have to ask Grace to fix it later. My neighbor’s dog Kirby will stare at you intently and appear to follow your every word if you look at him while talking about any subject, even degreeing a cam. Yet it would be unfair of me to be angry at him if I later asked him to degree a cam and he couldn’t.  I ask that anyone temped to write me an e-mail starting with “resizing Gif files into Dfxl files is easy, you just…” not get angry later. It has been my observation that in the spectrum of mechanical people, Tribe Grease Monkey has always been willing to accept that the Tech-Geek tribe was just born different, and leave it at that. However, the Tribe Tech-Geek tends to have the feeling that the Grease Monkeys have just been deprived of the opportunity to become a Tech-Geek, and if they just patiently instructed Grease Monkey and used small words, he would see the light and trade his ball peen hammer collection in for an Iphone. It’s actually motivated by a beautiful view of human nature, that given the opportunity we are rational enough to “better” ourselves. unfortunately, Kirby was born a dog, and I am a born Troglodyte, and no one should be mad at either of us.-ww)

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Hello William,

Here are some current photos of the SP-500 project. Since the early ’08 picture the wing primary structure has been completed. The wing is a constant chord NACA 63-618 that features a ring molded nose and tail rib with a very tight profile tolerance. The spar design has been computer optimized and utilizes Graphlight protruded carbon fiber stock for the caps and G-10 for all the point source load reinforcements. All the bonding operations in the wing were achieved with 1/8” cleco’s on a 2” to 4” spacing, alignment and bond constancy went off with out a hitch with no imprinting required. The fuel tanks are integral covering 3 bays (see the grey Jeffco coating below) with 2 suppression bays before the cockpit.

Below: The engine is a fairly Stock 2,700 cc (O-164). It’s all cocooned up in climate control right now, there is some minor work to be done before it can run but I do intend on getting a 5^th bearing set up on it before I fly. I’ve learned a ton about engine building between the Colleges and all the help from you and the Hangar Gang. All those years of working on the TSIOF-550J FADEC installation for the PA-46 I think gave me some hints on the gold color scheme.

All the tail feathers, flaps, ailerons and wing tips are hot wired blue foam. The H stab is removable but the V stab is fixed.

 Above, tailwheel assembly.

When I first started out in this project in ’06, I designed a couple machined components for Piper and had seen their CNC equipment in action but it was not until the hands on training you gave me on manual lathes and mills all those years ago at the old Edgewater hangar that the lightbulb really clicked. Since then I have manually machined many complex components on my Smithy for my plane including the tailwheel assembly and main gear/adapters. All this manual machining knowledge has proven to be very valuable on the P&W aircraft gas turbine work I do now.

Above: The wing butt rib showing the attach points that go into the spar box. Caps are carbon fiber .