GP ultimate 40 CG?
08-15-2012, 06:42 AM
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GP ultimate 40 CG?
I am just finishing with the Great Planes ultimate 40 kit. I tested the CG and found that it was extremely tail heavy.i had to add the weight of an estimated 1/2 to 3/4 of a pound. Can this be right?just for clarity, I built it exactly to manufacturer recommendations, down to the adhesivs. If they said to do it , I did. It also has an OS 46 LA, which I know is a little small. Any thoughts?
08-15-2012, 07:49 AM
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RE: GP ultimate 40 CG?
It will be underpowered with the LA. You need a larger engine for this plane. The 2 wings cause extra drag when flying. A good ball bearing engine in the 46 to 60 range would be the best choice.
Vince
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08-15-2012, 07:57 AM
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RE: GP ultimate 40 CG?
Yeah, I'm realizing that and will try to get a bigger one. As to the CG issue, you have any thoughts? Is that a normal amount of weight to add to the nose?
08-15-2012, 09:44 AM
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RE: GP ultimate 40 CG?
A bigger 4 stroke engine with a good pitts muffler will go a long way to solving your problem. My friend had one with a Saito 65, flew nice but not much vertical. He has put a Saito 82 in it now. Just waiting for him to finish and fly it. I would rather go bigger engine, for the weight you get more power.
Vince
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08-17-2012, 07:24 AM
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RE: GP ultimate 40 CG?
We've deleted several posts because this is not a discussion forum, and non-Great Planes reps are not permitted to reply to questions. This it the Great Planes/Top Flite/Flyzone support forum.
As long as your model is within the kit's weight guidelines, then you add as much weight as necessary wherever needed to get the model to balance. The Great Planes Ultimate Biplane .40-size is intended to be at 6.5 pounds as the maximum. To balance the model, you just add weight where needed to get it to balance. If you go over the 6.5 pounds, then you'll have to figure out why the model is so overweight. You should not have to make the model overweight to get it to balance.
The model will fly fine with a .46LA engine, but it won't have verticals as tall as with a more powerful engine. Takeoffs will be somewhat longer and climb will be less steep. It all depends upon what performance you're seeking.
As long as your model is within the kit's weight guidelines, then you add as much weight as necessary wherever needed to get the model to balance. The Great Planes Ultimate Biplane .40-size is intended to be at 6.5 pounds as the maximum. To balance the model, you just add weight where needed to get it to balance. If you go over the 6.5 pounds, then you'll have to figure out why the model is so overweight. You should not have to make the model overweight to get it to balance.
The model will fly fine with a .46LA engine, but it won't have verticals as tall as with a more powerful engine. Takeoffs will be somewhat longer and climb will be less steep. It all depends upon what performance you're seeking.
