FRCFoamies Mig 2.88 AFC- Plan Available!

Discussion in 'FRCFoamies Plans' started by F1wanabe, Mar 7, 2015.

  1. Flybyknight22

    Flybyknight22 Top Gun

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    One of the great features of this plane in my view.

    Here you can see the cavernous under belly and prop slot.

    Plenty of ground clearance for your props on the Mig 2.88.

    image.jpeg

    image.jpeg
     
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  2. homey666

    homey666 Top Gun

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    You are speeding up that feeling I need to build Blue Kow 2. I toasted #1 when I looked down and realised I was in an ant pile!

    Peter 2015-07-17 07.57.39.jpg
     
  3. Flybyknight22

    Flybyknight22 Top Gun

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    THAT!,.. Is a beautiful looking build Homes!
     
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  4. Flybyknight22

    Flybyknight22 Top Gun

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    I'm hearing you Homes,

    I have yet to fly it but my Sons and I really liked the compact area that FRCs ALPHA jet could fly in and after watching numerous videos of the 2.88 it looked like it has the characteristics we like in a plane with plenty of room for later modifications.

    We like flying the Alpha Jet at night loaded up with LEDs, so much fun seeing it in the sky at night!

    If the 2.88 proves to be as good as I think it is, after a few flights dialing it in we will then try loading it up with LEDs and make it a night fighter to go along with the Alpha Jet MK2.
     
    Last edited: Aug 20, 2016
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  5. F1wanabe

    F1wanabe Administrator

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    You're right about the 6x4x3 on the 450 zoom- I love that combo! We built the Mig 2.88 tough for low level flying so the prop clearance was a must. Hope you enjoy it!
     
  6. Flybyknight22

    Flybyknight22 Top Gun

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    Problems finding correct CG before maiden flight.

    Looking at the CG mark on the plane view my CG seems to be way off with these components.

    My best estimates based on this photo puts the CG approximately 6 inches from the front edge of the battery hatch.

    image.jpeg

    My CG falls approximately 9 3/4 inches from the front edge of the battery hatch as shown in this photo with the battery as far forward as possible on the lower tray.

    image.jpeg



    Hmmmmmmm.

    I might try to get the battery up on the small forward upper shelf.
     
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  7. homey666

    homey666 Top Gun

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    Hi FBK,

    I used the diagram and drew a line in the tray from just behind where the leading edge meets the fuse. That was my starting point. The battery actually bisected that line with a bit more towards the motor mount.

    Peter
     
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  8. FBK,

    I have my CG at about ~21.5 - 22cm mark in your last picture...
     
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  9. Flybyknight22

    Flybyknight22 Top Gun

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    Thanks homes for your help.

    Yeah I did that too but the CG marked there doesn't seem to balance the plane.

    It would be nice if there was a measurement in inches or mm's marking where the standard CG
    is in relation to something, like the front of the motor mount, forward battery hatch, nose of the plane or something but I can't find it anywhere.

    So where is the CG measured at or from on this plane?

    Does anybody definitively know?

    Maybe I just missed it somewhere in the thread?

    I will check through it again.

    Here is my pic where I marked what I think might be the CG in my battery try like you did but it's just a guess as no measurement I can find gives a good referance point, just a general photo from the plain view.

    image.jpeg
     
  10. Flybyknight22

    Flybyknight22 Top Gun

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    Thanks for your help malukk,

    I will try that and see what results I get.

    I Appreciate the measurement.
     
  11. I don't have the measurements on hand but here you go, if this helps:

    The red/yellow box is your "safe range"...
    The red line across is my recommendation for a perfect CG!
    Hope this helps a little better... :) Let us know how the maiden goes!


    image.jpg
     
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  12. Flybyknight22

    Flybyknight22 Top Gun

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    With the battery up in the 2nd deck of the battery tray the plane balances here which seems way off from the provided photo but "might" be closer than I think.

    Can't move the battery any farther ahead than this.

    I will try a 2200mah battery for more weight up front, then test CG again.

    image.jpeg
     
    Last edited: Aug 25, 2016
  13. F1wanabe

    F1wanabe Administrator

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    Flybyknight, the cg starting point is 1 inch behind wing break. Even with a 1500 the recessed battery tray should still be usable. I'll look back over the pictures, but do you have servos mounted behind prop slot by any chance ? With the servos mounted according to the planview you should have no problem getting the cg on the mark.
    [​IMG]
    If necessary, I'd suggest that you use a larger battery to get the battery into the tray since the centerline battery placement had a greater effect than a lighter battery would.

    Sent from my SM-N930V using Tapatalk
     
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  14. F1wanabe

    F1wanabe Administrator

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    Ok, i see from this picture that you have the servos behind the prop slot and yiu are using the ntm prop drive. Did you say you were going to use the 450 zoom instead? The combination of the servos that far back and the long, heavy ntm motor will require a 2200 for sure. The 450 zoom is an ounce lighter so that would help. I bet with the 450 you'd be able to get an 1800 to work. In either case, the cg mark is a starting point and you can go pretty far back from there. Do you have a 2200 to try? If not, do you have the 450 zoom?

    Sent from my SM-N930V using Tapatalk
     
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  15. Flybyknight22

    Flybyknight22 Top Gun

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    Thanks F1,

    Yeah I think you are right I might have to use a 2200mah battery to get the CG adjusted right.

    I have it mocked up checking CG using an NTM 2200KV motor temporarily as well, but will be replaced with the Zoom 450. I will check CG again with the different motor tomorrow.

    F1, that's a good point you make on servo position.

    Mine are behind the motor mount as you can see in the pic but they are very light 9g nylon gear servos but I guess that might be part of the problem as well.

    I will make some changes and try the CG again.

    The measurements you provide are outstanding!

    Thanks for those, I truly appreciate that and it helps tremendously.

    image.jpeg
     
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  16. Kiko12

    Kiko12 Ace Pilot

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    Why 40A ESC and 1500mah zipi ?? You never going to get 40A from this setup ???
     
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  17. Kiko12

    Kiko12 Ace Pilot

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    Why everything heavy is in one place ???
     
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  18. F1wanabe

    F1wanabe Administrator

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    Kiko, to obtain the cg and have maximum flexibility with power systems, we recommend placing all mass as close to cg as possible. This also serves to make the plane extremely maneuverable on pitch for aerobatics. This may not maximize with high alpha or hover like you get but overall the plane performance envelope is extended by placing as much mass around cg point, especially if you can use lighter components.

    Sent from my SM-N930V using Tapatalk
     
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  19. Flybyknight22

    Flybyknight22 Top Gun

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    F1,
    Thanks man!

    That's money on CG now!

    Balances with 1500 or 2200 batteries as arranged in the lower tray, also balances in upper tray with a 1300mah battery so lots of choices.

    Better to use the lower center of gravity in the bottom tray.

    Changed out the NTM and replaced it with a DYS BE-2208-2600KV motor.

    It is lighter and maybe a little more powerful than even the Power Up 450 Zoom.

    Bimo has been recommending this motor to me for quite some time so I decided to use it instead of the 450.

    This motor can safely throw a 7x5E on 3-cells, max current 43.1 amps at over 478 watts.

    This is a very strong little motor and tested very well on the Turnigy Thrust Stand.

    If they weren't so far away I would order several more. This one took over a month to get here.

    Here are the specs on the motor:

    image.jpeg
     
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  20. Kiko12

    Kiko12 Ace Pilot

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    Hmm, what happened after 500mah or 1000mah are consumed from your 1300mah battery or 1500mah battery ,you have choice, how you planning to deliver 400w
     
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