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BlackHorse SU26m 55cc COG problem

Discussion in 'Other Manufacturers' started by ron_owens, Sep 9, 2014.

   
  1. Hi,

    I purchased a BlackHorse SU26m 55cc recently and am having what I consider serious issues. It was on the cheap side for a plane of this size, but I put the cost down to the quality for the hardware (Aluminium U/C and wing tubes instead of carbon fibre...).

    However, when I tried to balance it at the recommended place (143 mm back from the LE), I found that I needed 5 pounds of lead to to balance it. After many emails to the dealer and the distributor, they finally said that the COG should be 145mm back from the LE.

    I realise that there is a range of COG depending on how you want to fly the plane (I've been flying a Pilot Sbach 55cc for that past 2 years). BUT... I decided to play safe and try to balance it at 150mm.

    It now takes 2 pounds of lead... The dealer says this is fine !!! However, I'm suspicious in that if it crashes, they will say it's down to pilot error...

    2 pounds of extra weight may be OK for a scale plane, but not for a 3D plane.

    Has anybody any experience of this plane or similar COG/weight issues?

    Thanks in advance

    Ron
     
  2. gyro

    gyro GSN Contributor

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    Ron I've never heard of this plane. Do you have a link? How much was it?
     
  3. Here is a link from the distributor... and the probable reason why you haven't heard of it is that not many have bought them !! I've flown some of their smaller planes over the years but never one of there... it cost approx $620 (£390 sterling / €490)
     
  4. gyro

    gyro GSN Contributor

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    Ron I think you forgot the link :)
     
  5. 3dmike

    3dmike 640cc Uber Pimp

    Wow that's a lot of weight! As one of my first warbirds I bought from a guy here in Oregon a Black Horse T-28 and it flew fine. No cg issues. Not the best quality as I had problems with the canopy. But to your issue. Do you have room up front to push the motor forward with some custom standoffs (Customstandoffs.com) a few inches? What engine did you go with?
     
  6. 3dmike

    3dmike 640cc Uber Pimp

    Snap a pic of the setup with canopy off and cowl off and we maybe able to give you some pointers!
     
  7. thanks Mike... the engine is an RCGF 55cc.... I just receiver some advice that 145mm is way to far forward, and 33% of the chord would be a more acceptable position for it.. I'm going to measure it tonight and see what its would be like with the COG there.. I can bring the engine forward a bit... there is lots of room as the cowl is very long ... I have some aluminium angles that I can extend the engine box with if needs be, rather than add weight... extra weight is the last resort ...
     
  8. AKfreak

    AKfreak 150cc

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    We need to see the setup. How are the elevator and rudder servo setup.
     
  9. Here is a sketch of my calculations...note..it's not to scale but the measurements are !

    THE MAC turns out top be 429mm, and 33% of this is 143mm (surprisingly what the manual says it should be). How, should the COG be this distance back from the LE of the wing at root or from the LE at MAC?

    BH_SU_MAC.jpg
     

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