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  1. W

    Lack of twin engine E/ABs

    Can't be done unless you certificate (both type and production) the engine also.
  2. W

    Units in Design

    When we designed the F406, which is a mixture of 404, 441, 425 and new parts, for production at Reims in France, they came back to us wanting to approve sheet metal in the nearest metric equivalent, eg. 1 mm instead of .040". We ended up refusing because it would have been a paperwork and...
  3. W

    Units in Design

    Burned into my memory: 32.2 lbm-ft/lbf-sec2
  4. W

    TURBINE - WHICH WILL PRODUCE ENERGY - AND PROPULSION

    Better watch out. I read a science fiction story once where the spaceship drive got stuck on and they reached such a high fraction of the speed of light, with associated time dilation, that they went through the end of the universe. Don't remember what happened after that.
  5. W

    Thread Rename: How to build a dynamometer for an aero engine running a prop ?

    Garret turboprops have had problems in the past with internal torque meters which require calibration. They used a Lebow torquemeter which installs between the prop and the prop flange. Normally used for ground runs only, but we flew one once and found that it didn't like the temperature...
  6. W

    Replacement Fluid

    An engine we used on a Cessna bizjet had a Lucas fadec. We never dealt directly with Lucas AFAIK, but the engine guys did not appreciate Prince of Darkness comments or jokes.
  7. W

    The propellers plane of damage ?

    FAA AC 25.905 for Transport Category airplanes, https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25_905-1.pdf, specifies plus or minus 5 degrees for conventional propeller blades with the exception that it could be larger for unconventional blades, such as propfan or scimitar, and...
  8. W

    Converting slugs per cubic foot to more tractable units for computing dynamic pressure

    I am a dinosaur but I always used lbm and lbf with the constant 32.2 lbm-ft/lbf-sec-sec
  9. W

    V8 engine Cessna 172

    Many years ago when I was at Cessna, there was a preliminary approach to GM to supply aircraft engines. I don't know many details except it didn't go anywhere. I imagine product liability, configuration control/QC requirements, and small volume were the cause of it not going anywhere.
  10. W

    Another multi wing game changer

    There was a joke going around Cessna years ago that if you use enough lifting surfaces you get interference thrust, and that is why the Starship needed such big engines to slow it down.
  11. W

    Drivetrain Power Loss

    Weight only really matters inasmuch as it effects such things as bearing loads and losses, or if you are accelerating the weight (which is exactly how an inertia dyno works).
  12. W

    Using a sprag/overrun clutch between the propeller & mounting flange

    If you pull to idle at higher speeds, what keeps the prop from over speeding? We were looking at a two engine single prop with overrunning clutches on an advanced design project and came up with a number of questions that didn't get answered before the project died.
  13. W

    Liquidpiston not dead

    The website says they have a new, patented thermodynamic cycle. I couldn't find any explanation or PV or TS diagrams explaining what this cycle is.
  14. W

    R 4360 Wasp Major

    It gets worse. I used to know a mechanic who had worked on c-124's in the USAF. He said that they changed cylinders almost as often as they changed spark plugs.
  15. W

    Twin engines packaged to replace O-360, both engines sharing a PSRU housing driving independent coaxial props?

    It has been tried. The Learfan and the Soloy 208 to name two, along with some non-publicized studies or advanced design efforts. The problem comes when you are trying to certify as a twin engine or for operations that require twin engines. Some failure conditions that are difficult to deal with...
  16. W

    Twin engines packaged to replace O-360, both engines sharing a PSRU housing driving independent coaxial props?

    My understanding, and what I can find online, is that he got a Part 33 STC for the engine package, but never got a Part 23 STC for the aircraft installation, although Special Conditions were issued. Interesting enough, the engine certification included some failure analysis requirements that...
  17. W

    Just when you thought FAR23 & the ASTM requirements were all sorted.

    I thought the whole thing was a mess from the get-go and never understood why the OEM's and alphabet organizations thought it was so great. The problem is that many of the requirements are poorly defined until the means of compliance are accepted, and the MOC are likely to take one right back to...
  18. W

    Twin engines packaged to replace O-360, both engines sharing a PSRU housing driving independent coaxial props?

    Most successful implementation of this concept was the Fairey Gannet as mentioned above. The first version of the Bristol Brabazon used piston engines, 8 Centaurus radials with two in each nacelle. This one was done in Wichita as a testbed in the 80's (2 x Allison 250 turboshafts) As...
  19. W

    Jet-A vs. diesel

    I have seen that engine certification special conditions require that applicant address effect of cetane number of Jet A, which is not a specification property. What haven't seen is how they did it.
  20. W

    Presurization - Whats it take ?

    Found a Simcom 340 manual online. You are right, there is a manual dump valve on each side with a check valve downstream to prevent backflow. There is a single heat exchanger in the belly after the two sides are teed together. A mixing valve directs the bleed air to flow through the heat...
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