From time to time there is mis-information, opinion presented as fact, or downright dangerous behavior talked about out there in the experimental aircraft world. Some comes from people with good intentions. Some comes from people relating experiences they had that are not good ideas to emulate. This page is a running list of issues that come up with the references for you to look up should you want to generate your own informed view. 8/09 - High altitude flying without oxygen Perhaps we as humans have to push the limit just because there is one. That is the only reason I can think of that anyone would fly at high altitude without being on oxygen. Someone recently wrote a post in an Internet forum about flying up to 17,500 MSL without oxygen. This is a patently bad idea, not something to be repeated. The FAA sets straighforward rules concerning flying as aircrew at altitude. Here are the facts (taken from: http://www.c-f-c.com/supportdocs/abo4.htm). FAA and Oxygen (From FAA Publications) Oxygen Requirements at Altitude. The FAA requires that all pilots flying their aircraft above 12,500 feet for 30 minutes or longer or at 14,000 feet or above during the entire flight must use supplemental oxygen. The amount required is 1 liter of oxygen per minute for every 10,000 feet. For example, at 18,000 feet there should be a flow of 1.8 liters per minute of oxygen available via a standard breathing device. The FAA requires there should be a device so attached to each breathing device that visually shows the flow of oxygen. (Nelson flow meters meet this FAA requirement.) The FAA also regulates that passengers must have supplemental oxygen available over 15,000 feet and that it is recommended that supplemental oxygen be used at night at altitudes over 5,000 feet.Effective Performance Time. This is the amount of time during which a pilot is able to effectively or adequately fly his aircraft with an insufficient supply of oxygen. At altitudes below 30,000 feet this time may differ considerably from the time of total consciousness (the time it takes to pass out). Above 35,000 feet the times become shorter and eventually coincides, for all practical purposes, with the time it takes for blood to circulate from the lungs to the head.
Ongoing - Microlon in Corvair motors  As of this writing, Goliath has about 200 hours on Microlon. So far, I have not detected any problems associated with its use. This is certainly not scientific. The jury remains out on the true long term effects of this product on wear, but I can say: - CHTs dropped ~25-40 degrees after I put the formula in the engine - Oil pressure was not affected in any way - Maximum RPM increased by about 70 RPM, indicating friction was in fact reduced 200 hours is a pitifully short time in the life of an engine. During that time Goliath has flow in 100+ degree weather, and way below freezing. We have operated from sea level to 11,500 feet. I am comfortable saying the engine seems to be working fine in those conditions. For now, my OPINION is it was not a bad idea to use it. Use your own best judgment, as there is precious little word out there on this product. 3/09 Mechanical fuel pumps Goliath uses the mechanical fuel pump the Corvair is designed for. This is a very workable solution. In my opinion this is a better way to get fuel to your engine than any combination of electrical pumps because a) the mechanical pump has millions of hours of operational experience, and b) if the engine stops (as in a mishap) the fuel stops. William Wynne (from Corvair Authority) used to recommend this set-up. In fact, in his manual from 1996 he did not recommend electric fuel pumps except as a back-up for a mechanical one. Specifically, he warned against takeoffs or landings with an electrical fuel pump on. Additionally, he pointed out "an accident with an electric pump on is very dangerous." I agree. On fuel weeping from the mechanical pump. I have experienced this myself. It happened twice as a result of bolts loosening. Bad preflights on my part, pure and simple. As with any critical part of your aircraft the fuel pump should be inspected regularly, and these problems went away when I fixed myself. Yes, even I have to relearn from time to time not to do things in a hurry. 3/09 Mild steel vs. stainless steel exhausts In building exhausts one can either build with stainless or "mild steel". The later is typically standard exhaust pipe from the automotive world. Both are valid materials for exhaust systems depending on your requirements. Tony Bingelis, author of numerous books on experimental aircraft construction, and builder of many aircraft, was probably one of the foremost experts in experimental aircraft construction techniques. His first of a dozen homebuilts was completed in 1966. He was a regular writer for SPORT AVIATION. His books and articles on homebuilding are considered by many, if not all, builders as the de-facto standard to build by. In his book Tony Bingelis on Engines he notes a VariEZE in his area has been flying with mild steel exhausts for 11 years, and that he was aware of stainless systems that did not last nearly as long. In his book Firewall Forward Mr. Bingelis notes, "Automotive pipes, when properly fabricated, are every bit as effective as stainless steel pipes." He goes on to state that they are in use on many aircraft engines and are working well in those installations. No where in any of his writings/articles does he express reservations about mild steel being used for exhausts in aircraft. I would encourage anyone interested in this subject read his books and log onto the EAA Member's site and do a search for exhaust systems. Such a search will turn up articles addressing the validity of using non-stainless exhausts. Stainless is lighter, but thinner. Stainless looks nicer, but is harder to weld. It conducts heat much slower than mild steel due to its chemical composition, meaning your under-cowl temperatures (especially when operating on the ground) will be lower. It is also expensive. Mild steel is heavier, and thicker. It does not look nice in its normal state (of course it could be painted or coated). It is easier to work with. It radiates heat into the engine compartment much faster than stainless. If you do develop a crack on a cross country flight, it is not hard to find someone who can patch it just about anywhere. It is very inexpensive. A recent commentary on a Corvair-related business site that sells stainless exhaust systems attacked someone who indicated mild steel was a suitable material for exhausts. It stated: "This person went on to make the preposterous claim that mild steel was more durable than stainless in exhaust systems. Such a statement undermines anything this person will ever say again." This and the associated photo of a burned/rusted out mild steel exhaust from a neglected test stand would tend to indicate mild steel is not an acceptable material for aircraft exhaust. In light of Mr. Bingelis' decades of practical experience in the matter, I will go with his perspective that mild steel is just fine for use in aircraft, and has the potential to outlast (many) stainless systems. Since Mr. Bingelis did not sell anything related to his opinion it is most certainly not a biased view. Goliath has a mild steel exhaust. It has 240+ hours on it and is doing just fine. It cost about $100 to have made up at a muffler shop vice $450+ for stainless. Your call. 3/08 Aerocarb and fuel pump systems The Aerocarb series of carburetors were designed to be simple gravity feed systems. The Aerocarb is highly resistant to icing due to its design. In fact, if you contact the company they will proudly tell you there has never been a case of icing with their carburetors (920-231-8297). The Aerocarb works in a very wide range of temperatures pulling air from directly under the cowling. I have operated mine from airfields well below freezing to well over 100 degrees, up to 12,500 feet in both temperature ranges. Goliath now has 240 hours on the Aerocarb with a fuel pump. Such a set-up does require a pressure regulator/reducer to work. Bottom line: This set-up works great and is (relatively) easy to install. I accept that "easy to install" is a highly subjective observation. |
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