FPVLAB

image
Page 3 of 123 FirstFirst 123451353103 ... LastLast
Results 21 to 30 of 1224

Thread: ZII: Project Hello Kitty

  1. #21
    Co-Pilot
    Join Date
    Nov 2011
    Posts
    1,623
    Wow Ian this is looking excellent so far. Can't wait to see the end result!

  2. #22
    on a vacation brosius85's Avatar
    Join Date
    Jun 2011
    Location
    bathurst nsw
    Posts
    2,250
    i dont wanna be an armchair engineer here ian, i know you have the experience and knowledge to make this thing work and work well

    having said that i am a little worried about the fuel tanks what is the wing being covered in? FG and epoxy? if you are expecting ANY flex, i think the tanks might break the weld at the join on the pipe between tanks.

    feel free to ignore these kinds of remarks, i have never built anything remotely close to this. just thinking out loud

  3. #23
    Cor blimey, guv'nor!
    Join Date
    Mar 2011
    Posts
    2,372
    Quote Originally Posted by londonguy View Post
    Wow Ian this is looking excellent so far. Can't wait to see the end result!
    Thanks londonguy. All advice gratefully received!

  4. #24
    Cor blimey, guv'nor!
    Join Date
    Mar 2011
    Posts
    2,372
    Quote Originally Posted by brosius85 View Post
    i dont wanna be an armchair engineer here ian, i know you have the experience and knowledge to make this thing work and work well

    having said that i am a little worried about the fuel tanks what is the wing being covered in? FG and epoxy? if you are expecting ANY flex, i think the tanks might break the weld at the join on the pipe between tanks.
    All excellent concerns! Other than extra carbon reinforcements, at this stage I don't (yet) intend to do any special covering, other than laminate and then vinyl. Although it'll have a very pokey power-plant, I will always need to be mindful of the limitations of the frame when flying it. No very high-G manoeuvres.

    The tanks however are extremely strong, far more so than may be apparent. Were you to grab both tanks and use them to bend the 10mm joining tube in the middle, the tube would bend and ultimately the tin-plated steel would tare, but the joins would hold. I've actually tried this in frustration when trying to dismantle some of my earlier sample tanks. In the end I gave up and made some new ones.

    A funny storey. With one of my sample tanks, I tried to remove the brass tube. Well, the soldering iron turned up to max wasn't helping, so I reached for the blow touch. HOWEVER, there was still a tiny bit of jet fuel left in the tank (and more crucially, vapour) from my test to ensure they were fuel tight. Well, after a couple of seconds the blow touch ignited the vapour and there was an massive bang and the tank shot across the workshop. The explosion *in* the sealed tank caused the top and bottom to balloon into a dome, yet they still all held together!

    Quote Originally Posted by brosius85 View Post
    feel free to ignore these kinds of remarks, i have never built anything remotely close to this. just thinking out loud
    Please continue to think out aloud! There WILL be stuff I've missed.
    Last edited by Ian Davidson; 23rd July 2012 at 07:28 AM.

  5. #25
    Cor blimey, guv'nor!
    Join Date
    Mar 2011
    Posts
    2,372
    Below is a pretty accurate estimation of where her weight will end up. Please note that 640g of this is fuel, so she'll get faster and faster during the flight.


  6. #26
    Michael Mictronics's Avatar
    Join Date
    Jul 2011
    Location
    Bavaria, Germany
    Posts
    1,010
    Please continue to think out aloud! There WILL be stuff I've missed.
    Not sure how you vent/pressurize the tank but since you supply the turbine just from one chamber isn't there a possibility that while banking the fuel will flow from one chamber to the other when the whole tank empties?
    I mean in a way that the chamber with the supply hose will be drained and the turbine sucks air in the fuel system which may lead to a flame out or RPM oscillation. Have experience that on full scale turbines already.
    Last edited by Mictronics; 23rd July 2012 at 07:53 AM.

  7. #27
    Cor blimey, guv'nor!
    Join Date
    Mar 2011
    Posts
    2,372
    Quote Originally Posted by Mictronics View Post
    Not sure how you vent/pressurize the tank but since you supply the turbine just from one chamber isn't there a possibility that while banking the fuel will flow from one chamber to the other when the whole tank empties?
    I mean in a way that the chamber with the supply hose will be drained and the turbine sucks air in the fuel system which may lead to a flame out or RPM oscillation. Have experience that on full scale turbines already.
    Both tanks will have vents, as otherwise the fuel won't drain evenly. Although what you say could definitely happen, I feel it would take a knife-edge flight for several seconds (around 5-10 sec) to truly empty one tank into the other. I don't even think this type of flying is even possible with the ZII. When it comes to aerobatics, it will be fast rolls and loops only.

    Also, turbines seem to cope with the odd air bubble in the fuel line remarkably well. Starve them of fuel and they flame-out quickly, but with the odd air bubble they just sputter.

    In one of my tests, I run the tank dry to the point where the top 2/3 of the metal clung you can see in one of the above photos was out of the fuel and exposed to air. The turbine was sputtering badly, but still running - albeit just.

    Oh yes, I will be wiring the EzOSD current sensor inline with the fuel pump. This will alert me should the turbine flame-out, as the ECU will cut the fuel pump.

  8. #28
    No Artificial Sweeteners. kev.au's Avatar
    Join Date
    Feb 2011
    Location
    Down Under ⇩⇩⇩⇩⇩⇩
    Posts
    1,823
    Cool project, I'll be following along mate!.
    Håvard Støre : Sir I humbly bow down to your balsa bashing abilities!!.
    chicken sashimi : my T-Shirts are all 100% guaranteed to get you laid.
    Roberto : you're a legend Kev.
    ssassen : I bow humbly before kev.au's greatness.
    Danub : Sir I humbly bow down to your tree bashing abilities!!.
    MonZon : Damn, Kev you are gooooood!.
    R. Montiel : For sure the limiting factor is the earth curvature

  9. #29
    Navigator henkvdw's Avatar
    Join Date
    Mar 2011
    Location
    Fountain Valley, CA 92708, USA
    Posts
    337
    To help with slosh, fuel cell foam may be useful, as used in race car fuel tanks.
    May be difficult not to melt it when soldering up the tank though.
    KJ6BFN

  10. #30
    Just dog tired. Wearyman's Avatar
    Join Date
    Mar 2011
    Location
    Buffalo, NY, USA
    Posts
    2,101
    Well, you could add a mesh grid into the tank to stop slosh. Some of that decorative aluminum sheeting that is sold at your local hardware store, cut into strips and then worked into a grid shape that is soldered into the tank. it will slow down the fuel movement but still allow for free flow of fuel through the tank. Something like this:

    http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051

    or this:

    http://www.homedepot.com/h_d1/N-5yc1...&storeId=10051

Page 3 of 123 FirstFirst 123451353103 ... LastLast

Similar Threads

  1. SWR meter - Do it yourself project
    By IBCrazy in forum DIY
    Replies: 1229
    Last Post: 26th March 2019, 06:14 AM
  2. Stratosphere Project
    By gaben in forum IFR - Video Link Discussion
    Replies: 230
    Last Post: 30th November 2014, 11:13 PM
  3. The Gigapixel Project
    By Blizzard1287 in forum DIY
    Replies: 35
    Last Post: 21st July 2012, 12:26 PM
  4. Tricopter project please
    By tunay in forum IFR - Video Link Discussion
    Replies: 4
    Last Post: 31st January 2012, 04:01 AM
  5. My Project
    By Jeffgiff in forum PILOT'S LAB
    Replies: 6
    Last Post: 14th November 2011, 07:36 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •