1. Hey guyz. Welcome to the All New Phlatforum!



    Sign Up and take a look around. There are so many awesome new features.

    The Phlatforum is a place we can all hang out and

    have fun sharing our RC adventures!

  2. Dismiss Notice

BiPi (Pronounced By-Pie) a twist on the Pi plane

Discussion in 'Double Wing Aircraft Plans' started by dz1sfb, Feb 19, 2012.

  1. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Had to knock this one out. Even got to test fly it today.

    Pronounced By-Pie, got the inspiration from I think it is SR71fan's DarkPi.

    Wingspan - 18"
    Wing area - 252.5 sq. in.
    Motor - 1700 Kv 24g Blue Wonder
    ESC - 10A Turnigy Plush
    Servos - Three 10g HK analog
    Battery - 850 mAh 2s
    Prop - APC 8 x 3.8
    AUW - 8.5 oz
    CG - 5.625" from LE at center of upper wing
    Airframe material - 4mm XPS foam (derivative of dollar tree foam)
    Rates - 100% aileron, elevator, and rudder
    Expo - 75% ailerons only (at this point)

    This build could have come out lighter with 5g servos, but the HK 10g units are what I had. That would be an easy 15g shaved off. Could drop to a Turnigy 2211 1700 Kv motor and loose another 6g.

    Also the foam that I used was a sample of product that we got for testing the shipping and container. It is much denser than Dollar Tree foam, but the same 4mm thickness. So a lighter foam would drop some grams on this build as well.

    Taking this one to the indoor facilty tomorrow to really shake it down and tweak it. Attached files BiPi.cnc (80.9 KB)Â BiPi.skp (1.7 MB)Â [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
     
  2. blindflight

    blindflight Moderator Staff Member

    Offline
    Messages:
    361
    Trophy Points:
    16
    Location:
    CA
    That reminds me of the "Enterprise" kinda / sorta. That's really KOOL !! Have any video?
    :doubleup:
     
  3. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    I will attempt to get video today.
     
  4. rcav8r

    rcav8r Moderator Staff Member

    Offline
    Messages:
    1,193
    Trophy Points:
    38
    Now that's twisted ;-)
     
  5. Gefahren

    Gefahren Member

    Offline
    Messages:
    205
    Trophy Points:
    16
    I usually wont go for anything that looks like a profile, but this plane is far to interesting looking to pass up. If it flys good I might try to make a larger one with a fatter fuselage.
     
  6. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Hi Guys!

    Had a great day with this plane indoors. Lots of interest generated, and got some final postions for the battery and CG (5.625" from LE at center of upper wing). Updated the SU and .cnc files in the first post to reflect those changes.

    Got some video that I will upload to YouTube tomorrow and post here as well.

    Gefahren,
    Bigger would be even better. One person even suggested flopping the rudder and elevator directions and flying it upside down for a standard setup making it a cool staggerwing. Then we went so far as to say put landing gear on top and bottom to do some real crowd pleasing by being able to land and take off inverted.
     
  7. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Heres the video
     
  8. blindflight

    blindflight Moderator Staff Member

    Offline
    Messages:
    361
    Trophy Points:
    16
    Location:
    CA
    Great test flying, it zips right along :good: .
     
  9. cmelton11

    cmelton11 New Member

    Offline
    Messages:
    28
    Trophy Points:
    1
    cool plane
     
  10. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Got to fly it again at the same facility today. Had alot more fun with it having incorporated the mods listed previously.

    There are a couple of things that I think it needs. On the hard landings I tend to pull the horns a bit loose on the big surfaces. I could use a longer base on the horns, but believe that a boss of foam at the mounting slot would get more grip on the horn and distribute the push pull forces over a larger area. Secondly, the interplane strut connection is a little week since it covers about half the length that the upper one does. Just going to add a small doubler on the inside of the strut, thereby doubling the glue surface area.

    Otherwise it is kind of fun to watch people check it out on the bench, just looking at it wondering what is it?
     
  11. thunder hawk

    thunder hawk Member

    Offline
    Messages:
    287
    Trophy Points:
    18
    Location:
    G.H. Boyd Systems, P.O. Box 235 Griffith, IN 46319
    That's an awesome airplane :banger: :banger: :banger: :banger: :banger:

    Thanks for posting the plans.
    GHB :cool:
     
  12. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Here a few more pics. Got the which way is up landing gear installed today.

    Attached files [​IMG] [​IMG] [​IMG]
     
  13. rcav8r

    rcav8r Moderator Staff Member

    Offline
    Messages:
    1,193
    Trophy Points:
    38
    Now that's cool. Hard to tell from the pic, but when sitting inverted, how is the angle of attack? Then again you may have enough power it won't matter. I didn't notice an over abundance of power in the video (nice video BTW) , but it's kinda hard to tell from an indoor video. Years ago my buddy did this to a plane (Hots), and had to have HUGE wheels on the top or else it won't take off, and even with the huge wheels it just lept into the air. Before he added the big tires it was a fast R/C car that turned the wrong way.

    And another buddy showed up to the field with a high wing plane (a Flair Sundancer) with a tail wheel on the top of the rudder; he loved to fly it inverted. When he told us that he wanted to do T&Gs with it and drag the tail, we told him it wasn't gonna take off... He insisted it would. Well on his "test" flight he yells over to us to watch as it was running down the runway on the tail wheel. It sure did look neat. The instant he tried to take off it got sucked to the ground..... Then it dawned on him...it can't rotate :shock:

    I only knew this was going to happen as I was the first in our group to try something like this...I used to get away with dragging the tail on my Kougar on a T&G as long as I approached it with the nose rather high, and powered out of the T&G. The one time I forgot and gave it down elevator it got sucked into the runway like I gave it the wrong elevator... That's when it dawned on my....can't rotate.

    So that's the foam your talking about over on RCG? Can't wait for it to come out... Waiting on the foam to build a modified Twin Cargo....
     
  14. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    I did get to fly it outside today, windy though it was. Lots of successful takeoffs and landings, and a couple inverted takeoffs as well. The vertical stab is the same height as the top of the top wing, and with the wheels under there I've got 1.375" clearance at the wheel for the wing to the ground. It gets off very smoothly.

    As far as power, most my flying in the video is half throttle or less. This plane could be built lighter with some different gear and lighter foam, but this one with the landing gear comes in RTF at 260g.

    The foam its built from is not really what we are getting that we've been discussing in RCGroups. Though white and smooth without waves, this foam is about twice as dense and 2/3 the thickness of the product we are bringing to market.
     
  15. rcav8r

    rcav8r Moderator Staff Member

    Offline
    Messages:
    1,193
    Trophy Points:
    38
    Glad the inverted take offs worked :D

    Any idea what the final thickness of the new stuff will be so I can design my tabs/slots?
    THANKS
     
  16. blindflight

    blindflight Moderator Staff Member

    Offline
    Messages:
    361
    Trophy Points:
    16
    Location:
    CA
    Like to try some of that foam .. :D What's going to be the cost & size?
    Thanks
     
  17. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Guys,
    For now I can only tell you this.

    Size: 6mm x 24" x 48" sheets
    Density: 2 lbs per cubic foot
    Color: White
    Other Characteristics: Flat, no waves, skin, or perforations
    Packaging: Shipped in a 16 sheet count box
    Cost: Not ready to release the final cost, but I think you will be pleased.

    Our first purchase order has been sent and recieved, and we are now waiting for a production date. Hoping to have our first shipment in a couple of weeks. Will likely be reordering by the end of March. We are doubling each order from the previous order, which means by the third PO we will be processing full semi loads.

    Otherwise I would like to keep the discussion to the RCGroups thread. However, when product becomes available, I will post a thread about it on the Phlatforum.
     
  18. Chuck

    Chuck New Member

    Offline
    Messages:
    260
    Trophy Points:
    0
    Neat as can be but I am confused about where to get 4mm foam. Anyone help me with this?

    Chuck
    ...somewhere in Indiana
     
  19. TigerPilot

    TigerPilot Well-Known Member

    Offline
    Messages:
    1,578
    Trophy Points:
    48
    At the dollar tree store. You'll have to remove the paper. Normally it's about 4.6mm but the last batch I've got was 4mm. I found that the best way to remove the paper is to buy at the dollar tree the spray bottle that is called 'LA's totally awesome carpet stain remover'. It comes in a red bottle. You spray the paper and while it's still wet you peel it of. Comes off like nobody's business.
     
  20. dz1sfb

    dz1sfb Member

    Offline
    Messages:
    116
    Trophy Points:
    18
    Chuck,
    You need not feel constrained to 4mm foam. You could go either way on thickness, 3mm for a really light build, or enlarge this puppy 150% for 6mm, or anything in between. This is a fun model, but not a beginners plane.
     

Share This Page