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  1. Jay Kempf

    Defend Raptor

    Do your best to make a case for the new Raptor design. Cite design parameters that have been offered. Context is a design program that ended up producing a prototype that met near none of the stated goals. How is the proposed reboot of this project going to meet the performance goals? Stick...
  2. Jay Kempf

    Another multi wing game changer
  3. Jay Kempf

    CG longitudinal offset to main gear contact patch....

    Basic question. For a tail dragger worst case for location of the mains is: 1. Ahead of the rear most CG when in the 3 point stance? 2. Ahead of the forward most CG in level attitude? 3. Other? For nose dragger: 1. Empty CG ahead of the main contact patch so it doesn't go on its tail?
  4. Jay Kempf

    Flexible wing structures

    This is a video of a 9 motor flexible wing. Just interesting structures experiment.
  5. Jay Kempf

    Clever landing gear design

    For the retract gear design nerds out there just ran across this guys work: CAD model animated: Pneumatic bench test: Hydraulic in place: Just thought the over center in both directions with a single actuator mechanism was very clever.
  6. Jay Kempf

    Power generating

    Regenerating power with an electric engine with a freewheeling prop has been suggested. The mission profile for this is climb, cruise, then on the descent you would freewheel the prop at some constant speed and at the cost of some drag you would be able to generate power to put some energy...
  7. Jay Kempf

    Mobile on W10 desktop after what looked like an outage?

    Did the site go down for a while and come back up? I had a redirect to some Amtrak scam site. Then when the site came back it looks like the mobile version. Is there software updates going on? And no latest post button?
  8. Jay Kempf

    Tooling board suppliers, prices, advice, BTDT experience

    Anyone have a good supplier or some knowledge of very high density polyurethane boards used for creating composite one off tooling. Been looking around and can't find a good source or much usable info. Have been doing CNC to one off tooling experiments lately. As the tools get large the...
  9. Jay Kempf

    Caution: no Experimental content

    Woohoo! Happy early Solstice to me! Finally got it home yesterday.
  10. Jay Kempf

    ShopTask 20 XMTC 1995 Looks like I am getting one of these turn mill drill combos. A friend has it in storage and the CNC part hasn't worked in a while. I have a complete set of redundant drives, steppers, boards, hardware, power supplies lying around so we decided to bring it...
  11. Jay Kempf

    100HP at FL10

    Was reading through a bunch of old threads about Suzuki and Honda based engines available in the HBA world. $10-15k buys you a bunch of R&D and a decent FWF/FWA package at about 100hp plus/minus. So I started looking around at engines (again). What I started seeing is that there is a lot of...
  12. Jay Kempf

    New battery technology using electrolyte barrier

    Anyone heard any more about this than this article. Sounds like they are through the sciency phase and actually able to produce usable batteries with this technology. Ilon Musk must be trying to buy this technology already. If any of this is true it would be a revolution. Lithium based batteries...
  13. Jay Kempf

    MachUp and other design tools from USU

    Just found this and thought I would share... Take a look at the "Open Source" menu and all the offerings. Very useful stuff.
  14. Jay Kempf

    Dieter Althaus

    I am looking at an airfoil from Stuttgarter Profilkatalog 2: AH 93 K 132/15 Does anyone have flapped polars for this airfoil for at least flapped CD vs. Alpha and CL vs. Alpha either tabular or graphical. Or more generally does anyone have an online source for the Profilkatalog 2?
  15. Jay Kempf

    Just found this airfoil analysis software and have been playing with it today I have run some runs already and it has all of the things that I want. But it has crashed a bunch and I got to the end of a couple analysis and it seems to want money to then get the optimized plot coordinates. Much more looking into this but it is really...
  16. Jay Kempf


    Does anyone have any real world experience with this program? I have an airfoil optimization task to do where I am especially interested in accurate drag and CL/alpha data and I need to be able to evaluate flapped and un-flapped configurations.
  17. Jay Kempf

    Aerodynamics is so complicated compared to other disciplines Dough McLean, retired Boeing Technical Fellow on fire debunking a lot of even elaborate theories of aerodynamics. It's worth 48 minutes of your life. Be forewarned it is full geek at full throttle. Enjoy.
  18. Jay Kempf

    Turbulent flow question

    Does turbulent flow have to impinge on a surface to create an increase in parasitic drag or do vortexes in free streams also contribute? If that vortex was not associated with lift it is not part of the induced drag calculation. It would have to show up in an interference drag estimation I am...
  19. Jay Kempf

    Maverick One

    MaverickONE | Maverick Jets Yikes!
  20. Jay Kempf

    Gust loading, aspect ratio, wing loading, cruise speed

    Been noodling on something for a long while. High cruise speed, high aspect ratio, low wing loading, and turbulence are all sort of mutually exclusive. With a high cruise speed and a low wing loading occupant comfort in turbulence is poor. Obvious. High aspect ratio wings absorb some gusts but...