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  1. jet guy

    Aero News Network Video - Terrible Raptor 1st Flight Review

    The landing gear wheel wells have absolutely nothing to do with the extremely serious pitch oscillations or the less dramatic roll instability. Some have suggested that his wells being close to the leading edge is a problem, but all retractable wheel taildraggers have the well close to the...
  2. jet guy

    Raptor Composite Aircraft

    No, I gave an OPINION about wing flex. If you disagree and have your own, differing opinion, that is fine. But if you are going to then present some kind of hypothetical scenario about camera stabilization [that frankly defies credulity, and which you don't seem prepared to back up with...
  3. jet guy

    Raptor Composite Aircraft

    I looked at your stills...and what are they supposed to mean, or not mean? Look, you've spent a lot of space here talking about image stabilization. I'm merely asking you to show something that actually backs up what you are claiming.
  4. jet guy

    Raptor Composite Aircraft

    How would you see flex if the image stabilization is distorting the footage? That would seem to be a contradiction, no? Or is there some way to tell when the camera is jumping as opposed to the airplane? Maybe you could take us through the video and show us where these camera anomalies are...
  5. jet guy

    Raptor Composite Aircraft

    Well, now we have image stabilization optical illusions? Look, I posted a video of an ultralight earlier with the same camera mounting under the left wingtip and there was no bouncing up and down. The Raptor even bounces up and down on the takeoff roll from that underwing camera. So every time...
  6. jet guy

    Raptor Composite Aircraft

    Are you sure the airplane is pitching up and down at that point? what we see from the camera is the airplane moving up and down relative to the lens. That means the wing is flexing. The only way to tell when he has the pitch excursions is to watch the cockpit footage where you can see the...
  7. jet guy

    Raptor Composite Aircraft

    It wasn't obvious to me that there was any elevator input, except after the initial liftoff where you could see him put in some pitch down. After that the elevator stayed pretty much motionless for the whole flight.
  8. jet guy

    Raptor Composite Aircraft

    Well...that's some creative interpretation of how the primary flight instruments work. Let's see if we can untangle this. The flight path vector [sometimes called flight path marker] shows where you are going to end up, showing your path over the ground. It's not showing anything about where...
  9. jet guy

    Raptor Composite Aircraft

    Maybe you could point out in Peter's video where the Dutch roll is actually occurring? Keeping in mind the basic definition of Dutch roll as rolling in one direction, while yawing in the opposite direction...repeated cyclically. We do have the PFD in view during the entire flight, so we can...
  10. jet guy

    Raptor Composite Aircraft

    You're comparing apples to oranges. In my opinion the amount of deflection and damping in a wing of that short a span and that depth of beam is dramatically excessive and insufficient, respectively...especially with that small amount of force applied.
  11. jet guy

    Raptor Composite Aircraft

    Yeah, I agree completely. That's just an absolute gobsmacker. Maybe not for the lay person, but for anyone even mildly acquainted with aircraft structures those few seconds of video hit like a ton of bricks. Yup. You can see also he has a guy holding the far end wingtip, and it still shakes...
  12. jet guy

    Raptor Composite Aircraft

    Yeah, I would be interested in hearing what, if anything, you actually know about vibration and damping [besides your 'observation' about 'little missile wings']. The simple fact is that damping characteristics are EXTREMELY important in aircraft structures and much effort is expended to find...
  13. jet guy

    Raptor Composite Aircraft

    The deflection is greatest at the tip, looks to be over a foot, easily. It is deflecting also at the root, but much less. Even this root deflection is surprising and not something you will normally see. If you are going to have deflection, you want it to be mostly in the outboard span. Again...
  14. jet guy

    Raptor Composite Aircraft

    The deflection in this wing can be seen here, where he's shaking it up and down at the tip. That is way too much deflection. And, even more important than the amount of deflection is the damping. Notice how long it takes for the oscillations to damp out and stop. It seems to keep vibrating at...
  15. jet guy

    Raptor Composite Aircraft

    Yes, that illustration from Jan Roskam is very nice. That's one thing I like about his books is that he has ample illustrations...🙂 Notice also how the big difference is that in the short mode the angle of attack varies greatly, while in phugoid it remains constant. This is the big danger with...
  16. jet guy

    Raptor Composite Aircraft

    What we see with the pitch excursions is called the short period mode. There are two pitch modes in dynamic stability [aka longitudinal modes]: the phugoid, which is a long period oscillation, over 30 seconds for one cycle [the cycle time can be approximated by 0.85 times speed in knots]...
  17. jet guy

    Raptor Composite Aircraft

    There was neither PIO, nor wind shear nor thermals in evidence. The AWOS report at the beginning of the clip reported winds 'calm'...there were only high cirrus clouds and no cumulus, which you need for thermals. Wind gradient between the surface and levels above surface requires a wind to...
  18. jet guy

    Raptor Composite Aircraft

    Just for a comparison, here's a little ultralight on its maiden flight, from the exact same camera perspective under the left wingtip. The thing is on rails. There is absolutely zero bobbing up and down from wing flex, control reversals, pitch oscillations...even though this has tiny wing...
  19. jet guy

    Raptor Composite Aircraft

    What a disaster...first the pitch excursions, which are continuous throughout and not caused by pilot input, other than perhaps the initial few seconds after rotation [Peter confirms this, and watching the elevator it's clear there is little input going on]. There continue to be irregularities...
  20. jet guy

    Raptor Composite Aircraft

    That's a good idea. So we see that of course at the lower climb speed the rate of climb increases, since we have lower drag at the lower speed. But is 90 knots really feasible as a climb speed for this airplane, considering that he rotates at 90 at a fairly light weight? I'm including...
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