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Seagull iSport CG

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Seagull iSport CG

Old 03-30-2018, 02:20 AM
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Default Seagull iSport CG

Hi all,

After putting together my Seagull iSport, its come out tail heavy. The manual states a balance point of 75mm from the leading edge. Its got a OS 55AX with a Bisson Pitts muffler up the front, mounted as far forward as possible. Servo's are Hitec HS-422 on all surfaces. The plane requires 320grams of weight up the front to balance. I have relocated the battery to the most forward position.

The model is being balanced upside down.

I am seeking some feedback or suggestions on how I could get this thing to the balance point.

Seagull iSport link - https://www.horizonhobby.com/product...0cc-arf-SEA210

Old 03-30-2018, 08:06 AM
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Brass weight spinner nuts from MECOA could be a solution if your spinner cone is of the type that allows it. Those spinner nuts come in different weights and thread sizes. ISport is a good-looking plane.
Like my Escapade 61, it too turned out tail heavy with the recommended engine size. I went with a larger OS 95AX, but then found that the landing gear was too short for the 15” prop. So then, I spent more money solving the issue with a taller landing gear. What’s with these designers?

Last edited by SA Flyer; 03-30-2018 at 08:09 AM. Reason: Added sentences.
Old 03-30-2018, 09:42 AM
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I can tell you what 40+ years of manf. suggested, starting, or beginning CG positions have taught me. They are very nearly ALWAYS WAY FAR AHEAD of where even a sport flyer will end up!

Also, nearly all of the China built models are safe to fly the maiden if the CG is somewhere near the leading edge to the middle of the wing tube. This nearly always puts you somewhere in that 25-33% of chord range - right where most builders will recommend you start. My opinion, FWIW. -Al
Old 02-06-2021, 07:50 AM
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You picked a real light engine, I've had a couple of these planes, the first had a laser 80 4 stroke and needed no nose weight, my current one has an os 61 fx on board, coupled with an alloy spinner and the battery poked up as far forward as possible and it doesn't have much extra balancing weight. The 61 is about 6 ounces heavier than the 55, by the time you've added a heavier prop etc it's getting on for a good 8 ounces more than your engine so just add the weight, after you've flown it a few times you can start to remove the additional weight until the plane flies like you want. I found fitting an aluminum engine mount can help balance issues if necessary.
Old 02-06-2021, 07:52 AM
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Forgot to say it's a real nice flying plane, I'd go as far as to say it's more user friendly than the pulse 60, especially with the flaps. BTW I used hitec 422s as well.
Old 05-09-2024, 04:58 AM
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Default Seagull Isport CG

Isport balanced perfectly without any additional weight. Using OS GT15 gasoline engine. Plenty of power. Unlimited vertical. Good basic 3-D manoeuvres. CDI mounted under fuel tank. Ignition battery mounted beside fuel tank receiver battery mounted above wing root.

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