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This Post Morphed> Again

Well due to the great responses ([link=http://www.elite.net/~runner/jennifers/thankyou.htm]Thanks Everyone[/link]). I believe my model is ready to fly -at least test fly. My first flight will be for 5 minutes due to the small fuel tank issue. My local hobby-shop is closed for remodeling until next Monday-!! I will address the fuel tank then...









Does anyone think that an OS 1.60FX is to much power for [link=http://www.cmpairplane.com/new_page_16.htm]this[/link] model? If I have overpowered it (which I fear) What can I do to compensate for the extra power?

The guys at the hobby-shop were very confident that I needed this engine- But I am not so sure?


-Origional Post-

OK- So I have finished my latest model [link=http://24.10.133.8/SU31/su31_1.jpg](See Here)[/link] [link=http://24.10.133.8/SU31/su31_2.jpg](And Here)[/link]
The problem is the weight? This model comes with the worst set of instructions I have ever encountered. According to the sparse instructions this model is supposed to balance at 150mm from the leading edge. See the link for balancing pics.
My dilemma is that I installed a OS 160FX and it still came out tail heavy by a fair amount. The manufacturer recommends a much smaller engine [link=http://www.cmpairplane.com/new_page_16.htm](See Website)[/link]

Has anyone set up a model from this manufacturer?

If not any advice will be appreciated...

NeoGenesis

My Feedback: (27)

I you want it to rip to the max, the 1.60 will do just that. It will give it what it needs to 3D. If you looking for more scale power........go a bit smaller.........that's what it boils down to. If it's so tail heave, move you servo's and battery's forward............get it as close as you can before adding weight.



My .02


Neo

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I was looking for extra power- I just wanted to be sure its not going to rip the wings off in level flight.

Stick Jammer

The bigger engine was a good choice if you would have needed to add nose weight with the smaller one. You're not gonna be flying this type of plane at full throttle when the nose is down or in level flight so the extra power won't be a problem. Throttle management is the key.

Dan767

My Feedback: (19)

Nice looking airplane. Have you used this engine yet? If not, before you fly this plane, please put a Perry Pump on this engine. You will need from Tower Hobbies the nipple from the OS 1.40EFI . Drill a hole in the top left (looking into the back of the engine) for the pressure tap. The part numbers are LXDG59 for the pump and LXWY11 for the fitting. Do a search about this engine on the forum. You don't need a starter for this engine either. Use a piece of foam large enough to plug the carb. Throttle open full, flip the prop 6 or 7 times, remove the foam, throttle just above idle, attach glow starter. Bounce it of the compression backwards using a chicken stick.

Broken

The fuel tank is directly behind the engine and it seems to run well. I have broken the engine in and ran about 2 gallons 10% through it. I performed the vertical test for about 30 seconds with no sign of sagging.

That being said I am still going to look into the pump for good measure.

My next problem is the fuel tank- The Chinese one that came with the model has no label on it- I think it is a 14oz tank? Static level tests at 3/4 throttle runs the tank DRY in about 10-1/2 minutes. This is not good>

I need to find a better fuel tank but the model is specifically designed for the generic funny shaped Chinese tank.

Skunkworks

My Feedback: (1)

Cool,

RevGQ

I have two of these Sukhois. I was able to fly the first with an OS 120 four-stroke. It probably slower than scale using a 15 & 16 inch prop. I remove the OS 120 and placed a Super Tigre G2300 in it on 18 inch prop. In both cases the plane was super tail heavy requiring anywhere from 1/2 to 1 lb. of nose lead. The ST G2300 flies it unlimited vertically @ 13 lbs.

The Second is mounted with a MVVS 160 gas engine. I haven't finished her yet, but I suspect that this high torquing monster will be superb on a 17-18 inch prop.

Suggestions for ya. Start the c.g at 4 3/4 inches behind leading edge, adding what ever amount of lead needed to balance. If you are comfortable with your landing you can then experiment with moving c.g location forward.
Second, beef up the landing gear, because one off the runway landing will reap it out. I beefed my inside lg block using fiberglass and resin.
Third, keep the 160 and leave rudder and elevator servos in tail. You will need the stiffness and positive control, particularly during low stalls.

I love the planes, though I wish they were lighter.
P.S. if you haven't attached the engine, make sure to add a quality ply outer fire wall. Soft mount is a good idea for attaching the engine as well. Good Luck!

Broken

I'm glad that the super heavy tail is "normal"> I had to add about 3/4- of a pound to get it to balance.

I did notice that the model came with conflicting instructions for CG. One set placed it at 140-150mm almost 6" from leading edge. The other set placed it at 25-28% from leading edge 4.5 to 5 inches. I will need to examine my CG to make sure it is within spec.

With this model did you set CG wet or dry?

Stick Jammer

You should always check the CG with an empty tank if it is forward. If you set it with a full tank the plane will get tail heavy as the fuel is depleted. This might result in a very unstable aircraft which could be extremely hard to land.