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Len Evansic

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    148
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10 Good

About Len Evansic

  • Rank
    Member
  • Birthday 02/22/1974

Personal Information

  • Real Name (Public)
    Len Evansic
  • Location (Public)
    Tehachapi, CA
  • Occupation
    NC Programmer & Mechanical Engineer @ Scaled

Project/Build Information

  • Plane
    Cozy Mark IV
  • Plane (Other/Details)
    Retracts, forward canopy and Cozy Girrrl strakes
  • Plans Number
    1283

Contact Methods

  • Website URL
    http://flightlinechairs.com
  • AIM
    len_evansic_dotmac
  1. What I meant about cold soaks is that under most normal conditions, the blue foam will be OK. If you intend to spend most of your time flying above 18,000 feet, then you will have an extended cold soak that may lead to skin delamination from the foam, during aeroelastic loading. One thing to note is that the polystyrene in the blue extruded styrofoam billets is already in a glass state. Similar to glass, it becomes more brittle at lower temperatures. This issue with polystyrene foam was discovered on a high-altitude plane at Scaled, that had these problems while flying very high for extended periods of time. The exact temperature that is required for the delamination was not measured. I have heard about this plane experiencing temperatures lower than -100°F, which is way colder than any Cozy will ever see. It was also implied that this type of failure was seen on other aircraft. I have seen extremely limited use of blue styrofoam, since I arrived at Scaled. It was conveyed to me that PVC is a much more reliable foam for wings that experience cold soaking. I did not hear about a specific testing to verify this, but I trust the source of this information. Scaled does a lot of testing with a cold soak chamber for joint designs and material suitability. It should be noted that PVC isn't hot-wired, nor is it used as a solid billet like polystyrene. Instead it is used as a stiffening core for ribs or skins. On a set of Long EZ wings, I saw extensive delamination between the skin and blue foam, under where dark decals were adhered. This type of delamination appears to be due to repeated localized melting of the foam. This is a good reason to not paint any horizontal surfaces with a dark color. -- Len
  2. Yes, there is a big difference. You want to use PVC foams like Divinycell near fuel areas, actually just about anywhere. Polyurethane foams shouldn't be used for any structures, because they become frangible with UV exposure and have a tendency to become brittle. The long-term effects on PU foams were not well-understood when the Vari-eze and Long EZ plans were written. Polystyrene foams are OK for wing cores, but they have a tendency to delaminate from skins under dark coatings (like N-numbers or decals) or after extreme cold soaks. Oh, and there is that whole pesky melting in fuel problem. -- Len
  3. As luck would have it, I was sitting beside Burt at a Half-Baked Lunch* at Scaled recently, when the subject of the Catbird came up. Nothing of the technical merit of the design was discussed, but the origin of the project was. Now, it is known that this plane was designed to win a CAFE 400 race, or more precisely, to take the efficiency record for this race, which is what determines the winner. While Burt is known far and wide as an efficiency enthusiast, this had less to do with his motivation than one might think. Well, Quickie Aircraft was down the flightline from Scaled (and RAF). At this time, the owners of the company were boasting of the efficiency of their Q200 aircraft, and of their ownership of the CAFE 400 efficiency record. Keep in mind, that although Burt had designed the original Quickie, the design was owned, manufactured (as a kit), and marketed by Quickie Aircraft. Burt did not go into any detail about his relationship with Quickie Aircraft at the time, but my read was that he was well-motivated to strip them of that record. The Catbird was designed to raise the bar well above where any Quickie derivative would ever be able to score on the CAFE 400 race. Burt also mentioned Nick Jones and his beautiful White Lightning plane, that was trounced by the Catbird. Nick Jones apparently was billed as "the Mouth of the South" in aircraft designer circles, and was quite boastful that he would triumph in the CAFE 400 record race. The series ended, and Catbird was the first winner of the successor CAFE Challenge prize. Gary Herzler stripped the Catbird of this record with his Vari-eze, shortly after the Catbird had won. Burt didn't acknowledge this after-history, and I don't think he is bothered too much by it, as one of his designs, built by a private builder, still owns this record. Also, the Catbird was not designed for the rules of the challenge, but rather the earlier CAFE 400. That it was the first winner of the CAFE Challenge just shows that it was still a very efficient design, all around. -- Len * The Half-Baked Lunch is a periodic event that we have at Scaled, where employees meet for lunch, and present their half-baked ideas. If you've gotten to the point of development where it looks like the idea is feasible, then it is no longer half-baked, and therefore ineligible for discussion. Some of these ideas proceed further and become fully-baked. The most exciting are always the ones that are possibly fermenting, rather than baking.
  4. I stopped by their booth and picked up their literature. None of it lists prices, and unfortunately, I didn't ask. Their OLED screens were sharp and bright, but this was indoors. I can't say how they will fare in full sunlight, nor after a few years of use. From what I understand, OLED displays tend to degrade over time, and although they have eye-popping contrast under the conditions that I viewed them in, they typically do not have the luminance to overcome full sunlight, and will lack the transflective contrast of a conventional LCD. I was more excited by their custom rocker switches and LED tip lights. -- Len
  5. I forgot to ask. How your project was coming, Dennis? I see what you have in your sig, anymore progress? I missed a lot of people at Oshkosh this year (oops, threadjack). -- Len
  6. I'm still at Scaled and doing well there, but the chairs are on an indefinite hiatus until we figure out how to deal with the insane California Board of Equalization. Yeah, I guess I dropped out for a bit. Before I came to Scaled, I built my plane factory out of my garage. I put in good lighting, and insulated it well for the typical -10° F winter days that I knew I'd have to deal with in central New York. I had a few small parts done, and then I moved. Two years without a factory put my project into deep freeze mode, and the last year has seen my new factory packed with boxes from moving. For most of my time here, I've been too busy at work to move on my project outside of work. That being said, myself and at least one other engineer at Scaled are redesigning fuselages for a Cozy-sized canard aircraft. I'm working on a stretched design with staggered seating and possibly different airfoils, and the other guy is designing a wider and smoother fuselage with an expanded grid backing, rather than sandwich construction. We'll probably combine efforts where it makes sense. For the curious, the expanded grid is a progression of the technique used for the reinforcement structure and lofting on Boomerang. It looks like the mesh netting you would see wrapping a ham. It could be formed on a male plug and then adhered to a skin from a female mold, or the skin could be formed directly over the grid structure, and a whole lot of body work done to make the surface smooth (which is how it was done on Boomerang). For the most part, this technique is not in any way compatible with standard Cozy construction. -- Len
  7. Well, there's always What Wikipedia has to say. Catbird is still hanging inverted in the main hangar, just as pictured in that article. It was retired, because Burt needed its engine, which now resides in the Boomerang. This plane is really a three-surface airplane, since it has a horizontal tail, in addition to the canard. It seats five, tightly. -- Len
  8. One thing to note with this particular test is that both MGS and Aeropoxy look absolutely equivalent when you add a reinforcement to either. This particular test is showing primarily the strength of the fiberglass, not the epoxies. When you look at the data for the epoxies only, MGS 285 is "superior" to Aeropoxy in that it has higher numbers for just about every entry. When you add a reinforcement into the mix, the fiber dominates the test results, as its strength is much higher than the epoxy matrix, no matter which epoxy you use. Two things to note in this test are the tensile strength and the elongation achieved. ~40 ksi is about four times higher than the strength of either of these epoxies, while ~1.5% elongation is about a third of what the epoxies will typically handle. What this is showing is that the glass used for this test has a ~40 ksi tensile strength and ~1.5% elongation when loaded at the fiber orientation used. When the glass breaks, the stress is already well above that of either epoxy, so they fail. In this case, both epoxies are equivalent. Now, what this testing doesn't show, is which epoxy would be a better structural adhesive for our purposes. The structural epoxy has to do its work on its own, dealing with peeling and shear loadings where the epoxy itself is the dominant load carrier. For this type of information, lap shear testing is the best indicator. This is the type of testing that the epoxy manufacturers should put out for their products. Unfortunately, that information is hit and miss between the different formulators, and the easier to test consistently tensile strength is what is normally published. Tensile strength is somewhat related to the shear strength, but surface preparation, reinforcement material and weave, etc. all contribute to this type of testing being difficult to reproduce or quantify effectively. -- Len
  9. Re-reading my original post, I feel that I may have come across a bit rough, so I want to add some context to my post. I missed this plane at Oshkosh this year (if it was there), mostly because I was quite distracted by events in Mojave, but I have seen it there in the past. I did see another plane that was apparently derived from a Velocity XL with complete carbon fiber construction and inboard vertical stabilizers. It hasn't flown yet, but that didn't stop the vendors from trying to hawk it at $140,000 per kit. No flight equals no interest from me. I wish success for any and all new designs, but it is difficult to buy-in when the demonstration of flight is missing, mis-stated, or non-existent. -- Len
  10. Has this new version of the Discovery/Freebird Xtreme flown yet? I know the one photo on the site is from Oshkosh 2005, when it was trailered to the show. Your current site doesn't show the plane in the air. The CG range looks to be larger than most EZ-types (from the posted drawing), was that tested or calculated? I am curious about the flying qualities, specifically stability in yaw and pitch. Does it display any dutch roll tendency? I think it's quite ambitious to pursue the whole range from LSA to Jet, to four-place, and I wish you the best of luck with it. Your current plane and the LSA are less than what I'm looking for. The Jet is way more than I'm looking for, but the four-place is just about right for my purposes. -- Len
  11. This last weekend, thanks to a generous ride provided by Marc Zeitlin, I was able to attend a great canard fly-in at Columbia, CA. I don't know what the actual count was, but I had noted at least 30 canards by mid-day on Saturday. Just about every type of composite canard was represented. The actual number of planes was rumored to be close to 40. For the benefit of those not in the Western U.S., Columbia California is an old gold mining town in the western foothills of the Sierra Nevada mountain range, near Sacramento. Columbia's airport is an uncontrolled field with available on-site camping. The town itself attempts to re-create the "feel" of the gold rush times by only allowing horse-powered vehicles in the town and having everyone who works in the local shops, dress in period attire. Canards de Mayo is a young event, this being the third year. I am tempted to say that it is a miniature Rough River, but since I haven't attend that event yet, I won't go that far. I could see this event matching Rough River in size in a few years, possibly becoming the matching book end at the lead of the summer fly-in season. I met a lot of great people at the event, and saw quite a few that I had met before at Oshkosh or at other airports. Of course there was a lot of hangar flying and perhaps a few people had too good of a time at the Saturday evening dinner (there was a little too much wine to drink). The presentations of some new canard aircraft designs were interesting, and informative. Likewise, the illustration of the dichotomy of brake and rudder pedal philosophy between that of most canard aircraft builder/fliers and the view from the Velocity spectrum was enlightening. All in all, it was a great event. -- Len
  12. My current guess is 10 years for this type of lunch. Less if I can figure out something that will pique his interest. Well, it won't be a speed demon, and there would probably be only about 50 safe flying days a year in Mojave for this plane. Then, again, the same could be said for almost all LSA type planes. The concept is still bouncing around his head, so I'd rather not spoil it. Exactly! He's not a fan of that part of the design. -- Len
  13. We did not discuss them that much. It was the last topic that I broached in our conversation. He said that he did the Defiant as a four-seat canard with side-by-side seating, because it's second engine gave it a much larger acceptable CG envelope. He has an aversion to putting more people at risk in the case of pilot negligence, and sees the ballast shifting that is required with the Cozy or any three-or-more person, single-engine canard as a potential disaster waiting to happen. Especially if the pilot is not the builder, or if the pilot is not sufficiently impressed by the need to maintain the aircraft CG within the acceptable range. Basically, he said that the movement of balast is something that is required in the Cozy, as you could have two heavy people in the front on one flight, and perhaps a very light pilot on the next flight. With the Long-EZ, you balast for the pilot, and (usually) no adjustment is necessary for the addition of a passenger, as they nearly sit on the CG. Also, as alluded by his joke, by seating in tandem, the canopy isn't forcing your head into any unnatural positions. -- Len
  14. As a preface to this post, I must insist that this is in no way an attempt to provoke envy or resentment from anyone here. I'm just relaying some stories and information that I got from Burt today. That being said, I'm sure that he would say the same thing to anyone here, if you were to sit down with him for lunch. Now, on to the stories. As the title of this post implies, I had lunch with Burt today. There is a tradition at Scaled, where each month, three employees are selected at random to have lunch with Burt. Today was my lucky day. Our conversation was wide ranging on topics from electric cars to his brother Dick's attempts at a political career. Invariably though, we discussed aircraft for the majority of the time. His all-time favorite aircraft is the SR-71, and he learned to fly and soloed in an Aeronca Champ 7AC. His favorite GA type plane is his Boomerang. The Boomerang, it's capabilities and design details took up about half an hour, by itself. Some of the conversation about the Boomerang slipped into the Adam A500 (another twin design) and another project, but I'm pretty sure I can't repeat any of those details in public. The Boomerang is his favorite, single or twin. I must say, if he were ever to license the design to a kit maker, I would do whatever I could to buy a kit for this plane. Yeah, you would have to buy two engines for it, but operating it at "economy cruise" would give you 180 knots at Cozy fuel consumption. Typically, the cruise is closer to 260 knots at 65% power. This plane has a 2,600 mile range on a full tank. Burt had a simple and elegant pressurization and cabin heating system worked out for this plane, but never got around to finishing the system before medical problems grounded him. We talked about his earlier designs, too. I had always scratched my head about the apparent missing link between the Vari-Viggen and the Vari-eze, since there are few similarities between them beyond being canard pusher type aircraft. According to Burt, the Vari-Viggen was his attempt at a personal F-4 Phantom. At the time, he was flying backseat in an F-4 as a flight test engineer. His goal with the Vari-Viggen was just to turn "a pile of wood" into a plane that had a fast roll rate, and a similar experience to the vertical-back Martin-Baker ejection seating that he was used to, in the F-4. The Vari-Viggen succeeded in having a fast roll rate, and according to Burt, it is probably the best plane out there in touchdown spot contests, since it comes down real fast due to low L/D. He then mentioned a design of his called the Mini-Viggen. There are a few mentions of this plane on the web as being an aluminum design that was never realized. These reports are wrong. This plane was going to be a kit, based on the mechanical components of a BD-5, but looking entirely different and made out of foam and fiberglass. The lack of a physical BD-5 kit slowed this plan, and Burt's attention shifted to making a more economical plane, which is where the Vari-eze came in. Economy is a special topic for Burt. He mentioned that the original plans-built Long-EZ, with the original engine (O235), could stay airborne for 24 hours on a full tank. Likewise, the Defiant could stay airborne for 12 hours on full tanks. When he first told his brother Dick about this, he was incredulous and the next day, he went out to see how long he could stay aloft. Burt was waiting for him to come back in 12 hours, as they were supposed to go to dinner that evening. Well, Dick came back over 18 hours later, and they had a very late dinner. We touched a bit on plane ownership and insurance issues. Burt confessed that the absences of hassles related to plane ownership have made up for the loss of being able to fly. I asked if he would ever get back in under the LSA license, and was surprised that he hadn't followed the issue much. He did indicate that although he's lost the passion for non-space planes, there may be one more airplane design that he's developed an itch for, as required technologies are almost at the right stage of maturity to use. This plane would be exceedingly efficient, and probably fall under the E-LSA designation, so he may fly again. At the end, I sheepishly asked Burt for his opinion of various derivatives of his design. He responded with a joke about how you can spot Cozy pilots (and co-pilots) by the sideways tilt of their heads.:battle: He then turned a bit more serious and explained that the reason he never did the side-by-side seating is because of the CG issues that have to be accounted for. Basically, two heavy people in the front can cause problems, and also the required movement of ballast. Also, he has worries about the ease of loading the planes into dangerous aft-CG conditions. He said I should catch him again some other time to discuss some of these issues. Well, that was basically it. With Scaled's current rate of growth, it will probably be about 10 years before I'm eligible for the lunch with Burt lottery again. This was definitely a red letter day for me. -- Len
  15. Don't hold your breath on the Starship coming back. The stories I heard about the unfortunate end of that plane (from un-named sources at Scaled) indicate that the plane was killed with malice and prejudice by one or more people who gained power within Raytheon/Beech at the time. The destruction of the prototype happened on the ramp right in front of Scaled's main building. It was destroyed by two monkeys that were hired by Raytheon to do the job. -- Len
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