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Old Jul 07, 2014, 09:18 AM
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United Kingdom
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Help!
Trouble getting F18 to fly - help needed

I bought a Skyangel Nano F18 35mm. I just can't seem to get it to fly.

TAKE 1

Completely stock PNF. Ran it on 2S Nano techs. It would sort of fly/glide for about 3 car lengths then come down fairly gentle slightly nose first. Tried full power, 80% power. Moved the battery back and forth. But it just seemed like it didn't have enough power to fly.


TAKE 2

Upgraded to a 12amp Turnighy Plush and some 3S batteries. I checked out the CG and it's between 33-36mm. If I throw the plane with no power on it glides fairly level for a car length or so. A bit like a paper airplane would and comes down slightl nose first.

With power on when you throw it, it just flips and twirls. Completely unpredictable and will land in a heap in any orientation only 3-10 feet away.

Again I've tried moving the battery forwards and backwards to try and eliminate a CG issue. But no matter what I did it appeared to have little or no affect.

Really looking for some help as I'm kind of out of ideas if what to look at now.



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Old Jul 07, 2014, 03:02 PM
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United States, TX, Dallas
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Tiny EDF

Sounds like you have found the proper CG location because it glides well power-off.
Use the location that begets the longest glide. Our jets are inherently unstable under power because the thrust exit is way behind the CG, pushing it. At low airspeeds this instability is more pronounced. You've gotta "be on it" during the launch sequence, using the ailerons to level the wings- the plane wants to roll due to the instant torque generated by the electric motor.

Hold the plane by the tip of the nose and hang it vertically, nose up. Apply full throttle. If the thrust equals the weight of the plane, it will hang there in midair. If it does, you have enough power to fly with authority.
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Old Jul 07, 2014, 03:48 PM
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What C rating are your packs?
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Old Jul 07, 2014, 04:13 PM
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United States, MN, Hermantown
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Quote:
Tried full power, 80% power
Did you think about starting at 50%-60% --
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Old Jul 07, 2014, 05:41 PM
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Quote:
Originally Posted by dedStik View Post
What C rating are your packs?
I've got a couple of 500mah which are 35C I think and a 370mah which is 25-45C. They where the best 3S batteries Hobbyking UK Warehouse had in stock in this size range.
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Old Jul 07, 2014, 05:43 PM
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Quote:
Originally Posted by CoolerByTheLake View Post
Did you think about starting at 50%-60% --
Yeah I tried quite a few different throttle settings from about 1/4 throttle, half and so on. Going to give it another try tomorrow night hopefully.
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Old Jul 07, 2014, 10:51 PM
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Try letting someone else throw it while you fly
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Old Jul 08, 2014, 12:47 PM
A-4 nut!!
skyhawk's Avatar
Vancouver B.C.
Joined Apr 2002
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Quote:
Sounds like you have found the proper CG location because it glides well power-off.
Use the location that begets the longest glide. Our jets are inherently unstable under power because the thrust exit is way behind the CG, pushing it. At low airspeeds this instability is more pronounced. You've gotta "be on it" during the launch sequence, using the ailerons to level the wings- the plane wants to roll due to the instant torque generated by the electric motor.

Hold the plane by the tip of the nose and hang it vertically, nose up. Apply full throttle. If the thrust equals the weight of the plane, it will hang there in midair. If it does, you have enough power to fly with authority.
that whole statement is complete nonesense.
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Old Jul 08, 2014, 04:08 PM
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made sense to me , what parts do find "nonsense"
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Old Jul 09, 2014, 01:51 AM View Post
blasiteomba
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Old Jul 10, 2014, 06:33 PM
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Try to ROG it from the grass, that way you are less likely to damage the aircraft from a bad throw or setup. If you can get it to ROG then it should be good enough to fly and trim out. I ROG my Skyangel F18 and F35 and they seem to do fine.
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Old Jul 10, 2014, 11:46 PM
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Quote:
Originally Posted by skyhawk View Post
that whole statement is complete nonesense.
Not necessarily. Hanging a jet vertically is a good indicator of how much static thrust it's developing. Since a hand launch starts at very low speed, the amount of static thrust is important.

With that said, a lot of static thrust is not a very good indicator of how fast the jet will go once it's flying.

One part that doesn't make sense to me is the torque statement since torque is usually a by-product of prop wash and EDFs have very little if any torque roll.

CD: Do you have someone that can help you with the hand launch? I recommend an overhand throw rather than side arm. It tends to reduce the wobbling on launch.

Daren
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Old Jul 12, 2014, 02:34 AM
James L
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Beck Row Mildenhall
Joined Mar 2009
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It sounds a bit like a thrust line issue
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Old Jul 14, 2014, 03:33 AM
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Had another go with this bird at the weekend. Before making the attempt I'd gone back and checked over the plane again. I moved some of the control horn links for more throw and checked as best I could the fan placement and thrust line (don't really have anything to work with, but there are some cutouts in the foam and it seems to be aligned well with them).

I did get it airborne this time after a few attempts, but it was only just. The flight didn't last long sadly there seemed to be almost no direction control. I managed to fly it out ahead of me and make a left turn, although it may have done it all itself. It refused to climb at anything more than a very gentle climb (maybe 15-20 degrees from the ground) and didn't really seem to want to respond at all to aileron inputs, e.g. full aileron did not make it roll and hardly made it bank.

In the end after making a wide sweeping left turn it banked over and came in nose first. It was also moving at one hell of a rate (fastest thing I've flown). So I don't know why it didn't have any real control. I accept part of it could be me, but when you are moving the sticks and the plane pretty much ignores them, I'm not sure what you are meant to do.

The good news is, some time with a hair dryer and some glue and it's back in a fairly straight order. So going to give it another go, although I might see about altering the throws again.
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Old Jul 15, 2014, 07:17 AM
James L
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Beck Row Mildenhall
Joined Mar 2009
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Seems to be problematic. It has coupled aileron and elevators are you sure this all doing what it should be eg apply left stick right ailereron down
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Last edited by TANGOSIERRAROM; Jul 16, 2014 at 12:06 AM.
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