F4u Corsair – Overweight and COG issue

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  • #55765
    Avatarshakti.baliyan
    Participant

    I have finished printing and assembling the F4U Corsair. I use Original Prusa I3 MK3 printer and used factory provided gcodes directly. The print quality came out decent and I faced no issues while printing. I used recommended electronics as well. Before test flight I checked its weight and balance. It seems to be too heavy. The manual recommends maximum take off weight to be 6400 gm (takeoff weight 5950gm) while my turns out to be around 6700gm. This weight is while using a 6s 5000mah battery not the recommended 8s 5000mah battery! By adding a 2s 5000mah, The weight will easily reach just under 7000gm!!

    Although I did not check each part’s weight before gluing but random loose parts that I weighed are almost identical to what is mentioned in the manual. However I noticed that main wheels weigh around 70 gm unlike 39 gm as mentioned in manual. I tried to slice it myself so that weight matches manual weight but printed wheel turned out to be significantly lacking in strength. So I am using my originally printed landing gear wheels.

    Will it fly with this much weight? Can you guys post your plane’s weight that actually works? May be we should have a thread for each plane where people publish their setup and printed weights etc.

    Second issue that I am seeing is that my cg with a 6s 5000 mah battery(830 gm) is at least 3.5 cm behind(towards tail) CG line mentioned in manual. If I add more batteries I add more weight to an already overweight plane and while it only corrects cg slightly. I intend to use HobbyEagle A3 super 3 stabilisation on this plane so Not sure if that will help or worsen the situation if CG is wrong? I am scratching my head now can you guys please help me here? Thanks.

    #55780
    Bernd1000Bernd1000
    Participant

    There is no doubt about having some additional weight in the nose./Add simply some lead.Screw it in place..Without the correct CG also a stabilization is not working.
    Its a wishful thinking to get the CG without any lead. imagine..the tail is four times longer than the nose of a plane. 1 gram in the tail makes 4 grams neccessary in the nose.
    and so on.

    Bernd

    #55809
    Avatarshakti.baliyan
    Participant

    Instead of lead I am thinking of adding more batteries and convert it into a 10s or 12s system. But this adds to total overall weight. My concern is how much max weight this plane can have so that it still flies OK. As you correctly said, more weight is needed at nose to bring CG forward. I am looking at tail section but can’t find anything that I can reduce there. I have added some custom clevis but removing those will not hugely affect cg.

    Anyone here who can please post their final plane’s weight, cog and configuration for reference? I understand that each one may have different equipment but still I can get some reference.

    #55820
    Petr ŠťásekPetr Šťásek
    Keymaster

    Hi Shakti,

    First of all, make the CoG right. It is very necessary.

    Move everything to the front and use the 8S setup as recommended. Probably it will make the CoG right.

    My Corsair with the paintjob and motor replica came up at 7.2 kg including the batteries and the CoG came spot on with the recommended setup. Flies great, very scale looking. I’ll be adding the 200 g soundmodule in the future and I’m sure it will make no difference in flight characteristics of such big plane.

    Being you I’d just tested the plane in flight, and if you find it too heavy, you’ll have to reprint anyway with lower flow settings.

    Please calibrate the flow on some thinwall section, the wheels are not as good reference.

    Our customers have also found that silver filament is slightly denser, so the result is heavier than when using other colours. Not sure what colour you have used.

    Good luck on the maiden flight.

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    #56708
    Avatarcomnean
    Participant

    Mine is 7300 g AUW. Flies with original setup but I found out that CG is better 10mm in front of recommended one. 8s 5200mAh at 980g total . added 210g of lead in the nose. In theory w/o lead and with performant sound module (weight around 200g) must work. Throws incorrect for elevator . Mine is set up +/-25mm.

    #59650
    Avatarfunnyjokes1.com
    Participant

    Really your post is really very good and I appreciate it. It’s hard to sort the good from the bad sometimes.You definitely put a new spin on a topic thats been written about for years.
    run 3

    #64626
    Avatarpigflite
    Participant

    I know this is an old post. I putting this info up hear for others to reference in case they are concerned about the weight.
    My F4U is HEAVY. 16.5 Lbs or 7.5Kg. Sound module, Eflite Power 160. 10s batteries. HVARS. Eflite metal retracts. Flies great. Still even floats on landing with full flaps.

    • This reply was modified 1 year, 4 months ago by Avatarpigflite.
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