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Davidz90

Eurobricks Knights
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Everything posted by Davidz90

  1. Davidz90
    Incredible . Very interesting idea and great execution!
  2. Davidz90
    I think it should work ok as long as the zeppelin is more or less hanging on them. In pure tension or compression, even a single liftarm can withstand 3+ kg. I had a gravity powered clock where the 2.5 kg weight was hanging on two liftarms. There was no damage after a week.
  3. Davidz90
    Thanks! Figuring out gear ratios took me more time than actually building the thing :D Lining up u-joints is definitely a good idea. Another thing I'd like to improve is to use a large turntable for frame rotation - that would be much less wobbly. Sure, I have few photos on Flickr: Orrery_5 by David_Z1, on Flickr Orrery_1 by David_Z1, on Flickr Orrery_2 by David_Z1, on Flickr Orrery_3 by David_Z1, on Flickr Orrery_4 by David_Z1, on Flickr
  4. Davidz90
    And now something slightly different: an orrery! It was a challenge to get proper orbital periods with possibly simple gear ratios. The result: 99.87% accuracy!
  5. Davidz90
    Thanks! This is my own design, not a set. No clue how much all the bricks would cost, but I guess not that much. The construction is actually simple: There are no rare/expensive parts, only bunch of beams, plates and technic bricks :P
  6. Davidz90
    Ken Kuo has many excellent animations of various escapements: https://www.youtube.com/channel/UC2h07cGBpJs8bF3OkgtJICg Other than that, there are many other animations. As for books etc, unfortunately I don't know any good references. The Arnfield, while conceptually a bit more advanced than other escapements, is actually pretty easy to pull off. The critical part is making sure that unlocking the escape wheel takes less energy than the wheel delivers by lifting the gravity arm back up. Basically, the escapement tuning is like this: gravity arm fails to lift? -> it has to be lighter or more torque is needed gravity arm jumps erratically? -> less torque or heavier arm is needed escape wheel fails to unlock? -> needs heavier gravity arm or less unlocking friction pendulum works for a while then stops? -> needs heavier gravity arm or less unlocking friction I have done recently an instruction for my Arnfield escapement:
  7. Davidz90
    Another design in microwatt power range. Combines very long period pendulum with "spring" made of carbon fiber strip.
  8. Davidz90
    One thing comes to mind: Everything worth doing is worth overdoing Interesting idea and great build!
  9. Davidz90
    Thanks! Limb strength is a major problem here. Ideally, they should be a single piece - a connection in the middle of a limb is just asking for trouble. Keep in mind that while the string has 5 kg pull, this is after the compound system - the limbs hold some 15-20 kg. I'm thinking about something like Ravin R15 crossbow - I'm arleady pretty close to it in overall dimensions, and the limbs are short.
  10. Davidz90
    Congratulations @MegaRoi, @Didumos69 and @Anto! That was a very fun contest
  11. Davidz90
    New version, with double power. This is what "giving up on safety margins" means
  12. Davidz90
    24: 10 25: 6 15: 4 9: 3 3: 2 10: 1 Good luck everyone!
  13. Davidz90
    Great design! Yes, the COG is in proper place. That panel is pretty much blanketed by front anyways and contributes very little to lift. Moving wing back is a good idea - You could unload the front a bit. Moreover, the current front design has pretty significant area and might generate lift on its own.
  14. Davidz90
    @agrof, great pictures and explanation. You are right, both configurations are viable. I'm no aerodynamics expert either, but my worry is that the stabilizer, as pictured, would not act as a smooth wing. Instead, it would just shove the air in one direction, like this (sorry for butchering Your sketch :D): img by David_Z1, on Flickr Anyways, lifting tail is a more tricky configuration - when the tail stalls, nose goes up and tail stalls even more. With stabilizer pushing downwards, stall causes the nose to drop - aircraft dives, accelerates and restores proper airflow over the tail.
  15. Davidz90
    COG is still far too aft - it should be slightly behind the leading edge. I'd suggest adding a beam at the front, and then adding weight at the end of it - this way You can shift cog without adding much weight. Moreover, the tail has to generate a force pushing it down - it might need some inclination. Maybe use a thin string to connect tip of vertical stabilizer and front of an airplane? That way You can bend the tail up a little and make it more rigid at the same time. Lastly, since dihedral is not an option with this construction, moving COG downwards (like in a hang glider) is a good idea too.
  16. Davidz90
    Maybe something like this would do? Russian Yak-15. The tube would be at the front. YAK-15 by Stewart Callan, on Flickr It would be interesting to see what glide ratio can be achieved. My bet is 1-2, so that angle of descent would be something like 40 degrees.
  17. Davidz90
    The plane has far too much mass aft. The planes centre of gravity should lie about at the leading edge of the wing and the horizontal stabilizer should be inclined a bit. Like in the image below, the stability is all about balancing forces: Balans1 by David_Z1, on Flickr
  18. Davidz90
    2kg on a pulley, so 1kg per single support point. Here it is:
  19. Davidz90
    Lots of good advice sir! This contest was a lot of fun for me, and Your clock inspired me to try studless construction in the contest entry. If I may add something, the Arnfield escapement is definitely worth a try. It is very power efficient - on my last big clock, 48h on 144 cm string (actually 72 cm with pulley). And most importantly, the pendulum is 100% separated from escapement wheel torque.
  20. Davidz90
    Incredible! Looks a bit like a steam engine, especially the escapement part . Soo many clever solutions here. I have never seen planetary windup mechanism like that and the constant torque converter is a very interesting design. In clockmaking, such mechanism is commonly called "remontoire". I was actually trying to incorporate one into my entry, with no success. Great job!
  21. Davidz90
    Video is ok for me. Interesting idea with geneva drive!
  22. Davidz90
    Awesome! I love the sound of this clock - the tick-tock is very symmetrical and steady, which is truly a great achievement, and done in system too! Just wow.
  23. Davidz90
    Maybe try grasshopper escapement, like this: or Galileo escapement I can attest that both of them are easier to get running reliably than typical anchor escapement. Been there, done that
  24. Davidz90
    The saw blade is a great idea, the designs definitely look like they would work fine! Obviously, regular gears give the most ticks per revolution, but their fine teeth are hard to work with.
  25. Davidz90
    I actually like that orange - blue contrast. The mixed gearing on pullback motors is a very interesting idea - essentially its like having a two speed gearbox, but simpler and more effective than actual gearbox!
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