Day: June 1, 2012

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Guest Editorial, Arnold Holmes On Affordable Aircraft…

Friends,

My Friend Arnold is well-known to many of the people in the Corvair movement. He hosted the enormously popular Corvair College#17, he has attended many others, and was one of our earliest contributors to the movement. If you look at the first pages of our conversion manual, Arnold is in the photo with us and our Pietenpol at Brodhead 2000. We had just flown it up from Florida.

Arnold’s experience in aviation is diverse, his talents are many. A skilled pilot and an IA, he knows traditional construction, but is well-known in the high-end composite industry, having worked for outfits like Legend and Adam Aircraft. He is addressed by the moniker “The Repair,” as in “Get me The Repair!”, because he once fixed a Lancair IVP that had its tail completely severed by a helicopter which ended up embedded in the top of the cabin in a ground collision. The project was delivered ahead of schedule and on budget.

Today his shop, AvMech, specializes in high-end GA aircraft maintenance, but he still is heavily involved in working class EAA stuff, he has revived his local chapter into a hard-core building group and he regularly flies his 1,000 hour VariEze, including taking it to Oshkosh last year with his son Cody. I have been close friends with Arnold for 18 years. We don’t agree on every small point, but he is always worth hearing out. Above all else, we both agree that the day belongs to the man In The Arena, not the critic on the sidelines.-ww

Corvair College #17 host Arnold Holmes and his son Cody at Oshkosh 2010

From Arnold Holmes:

I believe that airplanes for lower economic situations already exist. They are commonly referred to as “Plans built”. Although there is no doubt that various economic factors plague the ability for blue-collar people to own aircraft, it is not a complete deterrent. I often think that other factors for owning aircraft are often overlooked. For instance, our society has generally been conditioned for “instant gratification” and as such we have left much of our hands-on craftsmanship behind for the ease of assembling a kit. Granted that kits still require craftsmanship, but when purchasing a kit you are trading your time for money.

Second, I tend to think that our own success as an organization (EAA) is also our biggest failure. If you look at Sport Aviation Magazine from the 1960′s/70′s and even deep into the ’80′s you will find a treasure trove of new/one-off designs that often times were built by people who had no engineering degree. Sport Aviation Magazine was full of this stuff every month. As you pointed out in your post, J Mac started out doing a story about a TBM (not the Avenger by the way). Complete garbage for our publication and the membership should have taken the editors to task for such tripe.

Back to the point however, the failure in our success is really that we progressively featured only the very best award winners and show planes in the magazine. I think that over the years this has cultivated a common ideology that if you did not build an award winner than you are not worthy of building anything. People have come to believe that the requirements for success are so high that the ideology itself is defeating.

Now don’t think that I advocate doing poor work or skirting safety because I don’t; however I do believe that people get so caught up in trying to be the next OSH Grand Champion that they never finish their project. In addition, sport aviation as a recreational activity has become big business. How often do we think of something that we need and instead of saying “how can I build that” we instead pull out the Aircraft Spruce Catalog or call Van’s Aircraft and use the credit card for instant gratification. This drives the cost up way beyond where it should be. I am as guilty as anybody for this kind of stuff but I try to design and build as much of my own stuff as I can.

I think that it is mostly hopeful wishing to think that some “company” of any size is going to produce a low-cost airplane for the low-cost market. Why? Economy of scale might be a good way of looking at it. Despite simple airplanes being simple, there is only so much cheap you can design in and there is only so much cheap that you can run a company on. People and vendors need to be paid fair wages if they plan to stay in business and these things alone drive the cost up significantly. The sailboats you mentioned sold 30,000 copies; at that scale you have some financial cash flow and resources to work with. A cheap airplane may sell a few thousand copies if they are lucky; when you look at total investment, cash flow issues, vendors and materials (and insurance!!) it’s simply not possible to make an airplane in today’s market that cost what a sailboat or nice car costs. Assuming that sailboats and nice cars are within the reach of blue-collar society. This of course negates the ongoing cost of owning an airplane.

Now I still believe however that a nice one or two place airplane is within the reach of the common man. The common man however has to have his expectations recalibrated. Common man needs to set aside fancy kits, splashy avionics and powerful engines if he wishes to fly. Common man needs to go back and learn how to cut tubing and learn to weld with a gas welder, no need for an expensive TIG machine. Common man needs to curl up with a nice EAA book on woodworking, if they still sell such a thing. Common man must realize that his airplane will take a number of years because he will build it from scratch, one piece at a time, stick by stick and weld by weld (or layup by layup if you’re so inclined).

This return to the old ways is how common man will have his airplane. Yesterday I was asked to service a dead battery on a new Communist built airplane. As I poked around the plane becoming acquainted with its merits I quickly come to the conclusion that it was built using the same general engineering and manufacturing methodology as the Thorp T-18. Only this Communist airplane cost about $100,000 dollars more than the nicest T-18 you could ever find. Commie airplane flies 40 kts slower and is ugly as hell and is not rated for any aerobatics. Incidentally the cost of this airplane recently floated upward some 40% from its introductory cost. Now if the largest GA manufacturing company on the planet using Commie labor cannot produce anything cheaper than $150K and having a simple sheet metal construction that any homebuilder could replicate, how would it be possible for a small startup to pull it off. I know, I know there are several angles to that argument and I look forward to your rebuttal.

Arnold Holmes
A&P 2712249 IA
Av-Mech LLC
EAA Chap 534 Pres.

  

In a 2006 photo, Arnold Holmes and I stand behind the engine installation on a V-8 powered Lancair IV-P. This is an EngineAir package that I helped develop from 1993 to ’98. It’s 450hp, geared, injected, intercooled and turboed, and featured air conditioning and pressurization. This is complication. Eventually, about a dozen of these took to the air. They were stunning performers. I flew from Oshkosh to Daytona Beach in three hours and five minutes in our first airplane, cruising at 29,000′. The development of this engine took the work of many clever, dedicated people, and one guy with cubic yards of money, Jim Rahm. It worked, but taught me that homebuilders at all levels tremendously underestimate the effects of complication, primarily its delays and expenses. Whenever I read discussions about electronic injection or computer controlled engines, I can tell in an instant who has no practical experience with attempting to prepare these systems for flight. Get a good look at the size of the 5-blade MT propeller. Both Arnold and I have spent a lot of time working on projects that cover the full spectrum of experimental aviation, but after two decades, we both understand that getting the working man a place In The Arena is far more challenging and important than high-end products.-ww

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Corvair Cooling

Friends,

A number of people have raised questions about Corvair Cooling on the Internet. A lot of theory can be debated, but you can learn a lot more from a good example and a positive discussion focused on the details of installation the way we have done them. The photo below was taken in 2005, just east of our old hangar in Edgewater. In the background is the Atlantic ocean. The plane is N707SV, the Wagabond built as a joint project by members of our old Hangar Gang.

The Wagabond we built was based on a PA-22 airframe. It has 4″ longer gear legs than most Pacer conversions. This airframe is the same size as the four place, 150hp certified PA-22. As far as Corvair powered planes go, it is huge. Yet it is flown efficiently on a direct drive 100 hp Corvair. The plane weighs 804 pounds empty, because we were very careful not to put things in it like an interior beyond seat cushions. It has a full electrical system including a starter. The plane isn’t a speed demon, but combined with the Corvair it did something few experimentals can do: As a test we actually flew the plane with an 820 pound Payload on board. Yes, it has flown more than its own empty weight as a payload.

Above, the Wagabond sits on the flightline at Sun N Fun 2007, the second year it was there. The plane is a well-known flyer, as many people saw it at shows and at our old hangar. YouTube films of it flying have thousands of views, and it was seen in our DVDs.  It has been publicly demonstrated to work well over the past 7 years. It has had a long and trouble-free existence, despite being produced on a $9,000 budget for both the engine and airframe. No money was spent on electronics, flashy paint, or an interior. The money all went to a solid airframe and a sound engine. (In the background is Dan Weseman’s Wicked Cleanex.)

The Wagabond has excellent cooling. Florida is known to be a warm place, but the plane never has had any kind of cooling issue. When discussing something like cooling, you can often appreciate a point best by examining an extreme example. The size and lifting capability of this plane, combined with a slow climbing speed should make this plane the most difficult Corvair to cool, yet it has no such issues, it just works. The plane uses our standard components and a standard aircraft approach to cooling design.  All the concepts are nothing new, they appear on countless certified planes like Cessna-150s and 172s. There could be no more proven cooling concept in general aviation. Out of the 60,000 150s, 152s and 172s built you never hear about one of them frying an engine from a cooling issue, despite the fact that they are most often flown by students, and almost none of them have CHT gauges. They work because they have generous inlet areas, well thought out exit areas, their timing is set correctly, they have a regular aircraft carb that doesn’t lean out, and they have a large cooling plenum that covers the whole top of the engine, sharing air to whichever side needs it. The Wagabond also works because it shares all these characteristics.

The above photo shows that the plane uses one of our regular Nosebowls, with the air inlets trimmed to 4-7/8″ diameter. Notice that the plane not only has a front mounted alternator, it actually has an oversized pulley mounted on it. Although this inlet lets in slightly less air than the other side, it doesn’t matter because the air is freely shared by both sides of the engine.

Above is a photo of the bottom of the firewall, looking in from the side of the cowl. Note the rolled piece of sheet metal that smooths out the airflow exiting the cowl at the base of the firewall. Notice that the exit area is twice as large as the inlet. The carb on the plane is a Stromberg NAS-3, a regular aircraft carb. These are set to go slightly rich at full power, a very big part of preventing detonation on a full power take off and climb out. Motorcycle carbs, particularly CV ones that are subjected to even slight amounts of ram air pressure, almost always go lean, making the engine detonate. The number one reason people don’t use aircraft carbs is cost. This one in the picture was bought out of a flymart and set up with old bits and pieces: Total cost, about $200. Even a guy buying an overhauled one outright from Russ Romey at D&G will only spend $800. Pricey, but a whole lot less than damaging your engine with detonation. When building a plane, buying a great carb comes before glass cockpit stuff, avionics or paint jobs. The airbox on the bottom of the carb is a standard aircraft one. Carb heat air that is not used exits the bottom of the box and immediately heads out of the cowl rather than heating anything up. 

The above photo shows the underside of the cowl. Notice that the plane has a smooth ramp for the air to flow out, and it has a very crucial fixed cowl flap, the lip on the leading edge of the exit opening. The sheet metal roll from the photo above is visible in this photo.  The 5/8″ tube hanging down is the crankcase vent.

To give a good idea of how big this plane is, note the crankshaft centerline is 62″ above the ground in the three-point attitude. The top of the cabin is 80″ from the ground. This plane’s best climb speed is only 65 mph, but it can climb at this speed, at full weight, at full power, on a 100F day without overheating, for any length of time.

The above photo shows an overview of the cooling baffles. We have dozens of Corvairs flying with this same arrangement. It works, period. In the back of the photo is the Distributor. If I wanted to make a Corvair overheat quickly, I would just set the timing by ear to the smoothest running setting. This sounds cool, but it will cause the engine to detonate and overheat on the first full power climb out. Timing set by ear in a Corvair always has too much advance. Builders must use a timing light: They are cheap, there is no excuse, but still 15-20% of builders with running engines have never set the timing on their engines with a light at full static RPM.

If a builder is having an issue, the first question to ask is “What is different from the Wagabond?” a plane which clearly works. In many cases the plane that isn’t working is trying a combination of using low-grade car gas, not setting the timing, having a carb that leans out at power, and no cowl exit design. Builders can eliminate these issues by taking advantage of the things we have learned over the years. -ww