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rgmwa

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Everything posted by rgmwa

  1. rgmwa
    PC680 weighs 7.0kg.
  2. rgmwa
    I use an Odyssey PC680 AGM with my 912ULS. It's about $160-$190 from various retailers.
  3. rgmwa
    Like Morry Hummel, Vans have over time incorporated improvements in the RV-12, and no doubt the other RV models, based on suggestions and modifications made by the early builders and documented on Vans Airforce website. Even yours truly can claim a couple of very modest contributions that have since appeared in the current kit.
  4. rgmwa
    Agreed Onetrack. I've read the Silver Centenary story and also had a good look at it and watched it fly more than once. It's hangared at Serpentine, where I keep my plane. Ford did a remarkable job - it looks right and in engineering, that's usually a pretty good guide as to whether something is right. And as you say, just because an aircraft was `professionally' designed doesn't mean that it's going to be any good. There are plenty of examples of professionally engineered flying crocks in the history books. Nor does having formal engineering qualifications make you a gifted designer, just as having no formal training doesn't mean you can come up with an excellent design. I learned a lot about aircraft construction from assembling (I won't say building) my kit, and am currently one of the mentors helping a bunch of high school kids put together another RV12. My own preference for a plane that I and others are going to fly in is a kit from a reputable manufacturer, but I'd also be happy to build off plans if I had the time and the right equipment. It's just a lot more work. If I was going to design my own plane, as I said previously, I'd want to make sure I'd done my homework to know what I was doing. In engineering, it's knowing what you don't know that keeps you out of trouble. So far, so good.
  5. rgmwa
    Yes, I’m happy to build and fly a plane that I know has been well designed and tested, and to make relatively minor modifications that I know won’t its airworthiness. Nevertheless, even though I’ve spent the last 40 years designing structures for a living, I’d still think twice about tackling an aircraft without doing a lot of homework. Hats off to the true experimenters though.
  6. rgmwa
    It’s not the ‘design by eye’ part that would would worry me. It’s the ‘confirm by test’ bit that would make me think twice about buzzing around at 1,000 feet to find out which part of my design needed improving.
  7. rgmwa
    The struts are not very long which is good, but I'd suggest "When in doubt, make it stout!"... especially when your life depends on it and you're not sure what the loads are. There's a big difference in strength and stiffness between 20 and 25mm tube for the same wall thickness, and steel is a lot stronger than aluminium (obviously). Also if you're putting bolts through it, the bigger tube will lose relatively less cross-sectional area.
  8. rgmwa
    How long is the strut?
  9. rgmwa
    I agree with Yenn. You need to have a pretty good idea of the tension and compression forces in the strut and its fittings under all loading conditions, and also how to design in timber if you're not building from a plan.
  10. rgmwa
    The highest grade I found for seasoned hoop pine after a quick search was F17. It's a softwood and AS1720 (Timber Structures: Part 1 - Design Methods) - gives a characteristic bending strength of 42 MPa and tensile strength parallel to the grain of 22 MPa for F17. However, these basic values need to be modified by a whole lot of factors if you want to design something.
  11. rgmwa
    I don’t think it’s racist to notice difference. It’s obvious that people from different places and cultures have different characteristics. The problems start when those differences result in differentiation and discrimination. We have many different races and cultures here in Australia, but compared to many other countries like the US, we do remarkably well in creating a pretty homogeneous society. I’ve always thought the Australian accent is a great unifying factor in smoothing out cultural differences over time.
  12. rgmwa
    I wonder about the Wandering Albatross. They spend many weeks flying day and night over water and you would think they might get caught in IMC. Even night flying would be tricky. I suppose they could land but taking off from rough water wouldn’t be easy. Interesting question.
  13. rgmwa
    Good news! Looks like overseas travel is back.
  14. rgmwa
    He makes it look easy. I spent some time watching one of these in action on the North Island a few years ago. It takes a lot of skill fly one of these in that hilly country.
  15. rgmwa
    Looks like those South Africans are in business for the long term. Good to see. Anyone know what a Sling 2 kit costs in Australian dollars?
  16. rgmwa
    Can't vouch for the Sling from personal experience, but it was designed to the EASA VLA standard with an MTOW of 700kg, so when it's sold as a 600 kg LSA, something has to give. However, I have an RV-12 and it does everything that Vans say it will do. My only complaint is that the standard 20 US gal /75 litre tank with a 912ULS is marginal for Australian distances on long trips. I've increased mine to 25 gal which works well, but the trade-off is that I can carry less weight in the baggage compartment with full fuel. A couple of other RV-12's over here have been modified in the same way. However, the 912iS is now the standard RV12 engine. It's significantly more fuel efficient than the ULS according to Vans own testing, so their 20 gal tank even goes a bit further than my 25 gal tank according to the POH.
  17. rgmwa
    Scratching your nose or waving to a friend is probably not recommended either.
  18. rgmwa
    My mistake. Twenty seven gals is a lot better and would give it good range. If they can increase MTOW then the plane is starting to look pretty good in terms of performance, although maybe not aesthetics. We’ll have to wait and see whether they get serious about Rotax. These engines are probably gaining more acceptance in the US through the LSA market with aircraft like the RV12 and Sling, but no doubt the traditional engines are still well ahead in market acceptance. Time will tell.
  19. rgmwa
    It wii be interesting to see if they end up offering a Rotax alternative as Ken Krueger suggested in the video. A 912iS would with reduced weight and better fuel efficiency could make a significant difference to payload and endurance. A 16 gal tank is not much for a plane that looks like it should be a pretty rugged back country tourer. Less of an issue if their main market is flight training.
  20. rgmwa
    Ken Kreuger was Vans chief aeronautical engineer up until a few years ago, and designed a number of the current range of RV's, so he knows a thing or two about aircraft design. I'm not particularly sold on the Vashon though, although I guess they've done their market homework.
  21. rgmwa
    I don’t know the legalities of building from a secondhand set of numbered plans that are not in the public domain, but if you’re willing to wear the cost of building a plane then surely you can afford to buy a new set of plans to make sure you’ve got the latest version. If it also buys you factory support then it makes even more sense to not try to cut corners.
  22. rgmwa
    I remember when my boss and I were invited to another consultant's office to have a look at the owner's brand new fax machine. It was very new technology then. You had to hook it up to a telephone handset and dial up. The owner enthusiastically described what it could do. My boss was suitably impressed and said, "That's great!", and then added, "... but who else has got one?" It was a few years ago now.
  23. rgmwa
    Probably old news, but I only came across this recently. Quite a few aircraft sitting out there in the desert. https://www.escape.com.au/news/incredible-images-of-plane-graveyard-near-alice-springs/news-story/186572ec9da57bb6e6248f915effe876
  24. rgmwa
    Yes, with Trump it's always somebody else's fault.
  25. rgmwa
    Churchill didn’t then promptly claim he was treated very unfairly and try to overturn the election. Go figure.
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