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Old Mar 01, 2015, 06:18 PM
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Canada
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My original prop was horrible to balance and I ditched it quite early on. No matter what prop you use, you must balance it well. Vibration is never a friend to any flight controller. I run mine on 4s, so I use a 10X8 prop. If you are dragging the prop on landing, you should consider a folding prop of a similar size. You'll need a "prop stopper" for a pusher. Also set brake to ON. I've been lucky in that the prop has never dragged on the ground when landing. You must make sure you shut throttle off before touch down.
Since it's a rear motor pusher, you only need to make yourself a hard plywood mount and glue it in.
These guys sell all kinds of folding props, spinners, and prop stoppers.
http://www.espritmodel.com/folding-propellers.aspx
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Old Mar 02, 2015, 01:18 AM
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Norway, Finnmark, Hammerfest
Joined Jan 2014
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Originally Posted by Ponpont View Post
Yes other people tell me that 4s will be overpower so i thinking about 3s 10A or 8A
I want it like a glider

Like i said, i use 3S 8000mah battery and i cruise around 5-7 amps depending on weather conditions. Overall cruise is like 6-7amps if there is a little windy.

Motor: Sunnysky 2820 800kv
Prop: 12x6" APC

I want to try with 2x8000mah just to se how it flies and the flying time but the total weight will be 3,4-3,5 kg then. I am a little afraid of how the wingspares will handle the extra 590g of weight.
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Old Mar 02, 2015, 03:30 AM
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Joined Oct 2013
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Originally Posted by xviper View Post
My original prop was horrible to balance and I ditched it quite early on. No matter what prop you use, you must balance it well. Vibration is never a friend to any flight controller. I run mine on 4s, so I use a 10X8 prop. If you are dragging the prop on landing, you should consider a folding prop of a similar size. You'll need a "prop stopper" for a pusher. Also set brake to ON. I've been lucky in that the prop has never dragged on the ground when landing. You must make sure you shut throttle off before touch down.
Since it's a rear motor pusher, you only need to make yourself a hard plywood mount and glue it in.
These guys sell all kinds of folding props, spinners, and prop stoppers.
http://www.espritmodel.com/folding-propellers.aspx
Many thanks Xviper!!

I'll take a look at these folding propellers and see if I find ideas for wooden mount .
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Old Mar 03, 2015, 04:54 PM
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Joined Apr 2009
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Originally Posted by odnanref View Post
Hi Guys,

This weekend I rebuilt my fx79 and I went to see how it flew. I had some problems and I wonder know if tha also happened to you. I am using the PNP version, motor 950 kv and the original propeller 12x3.8. When apply throttle for tacking off I noticed that the plane was vibrating a lot, but as usual. Within 10 seconds of flight autopilot goes crazy (MyFlyDream), the artificial horizon pointing me that the plane was turning 180 degrees and it was flying level. I thought the AP would have fallen so I decided to land to put right again.

Upon landing propeller touched the wet ground and broke the motor mount! propeller left intact ... When opening the dome, I note that the autopilot was not dislodged. My conclusion is that it may be due to the vibrations of the aircraft, what do you think about it?

Moreover, any of you has replaced the motor mount for a harder one? I think I'll also change the original propeller, any suggestion ?
Was ur prop balanced ? If ur prop is not balanced it will vibrate the crap out of the autopilot. U could try a different prop 12x6 12x5 11x6 etc and make sure its balanced. As for ur motor mount they sell them at hobby wireless or u could try the aluminium one that suits the FX61 thats sold on on ebay, would definitely be alot stronger. It "should" fit the buffalo. Both the Buffalo and Phantoms stock motor mounts look identical to me.
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Old Mar 04, 2015, 03:24 AM
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Originally Posted by chris_p82 View Post
Was ur prop balanced ? If ur prop is not balanced it will vibrate the crap out of the autopilot. U could try a different prop 12x6 12x5 11x6 etc and make sure its balanced. As for ur motor mount they sell them at hobby wireless or u could try the aluminium one that suits the FX61 thats sold on on ebay, would definitely be alot stronger. It "should" fit the buffalo. Both the Buffalo and Phantoms stock motor mounts look identical to me.
Thanks Chris,

No, my prop wasnt balanced . I will try with 12x6 APC, I have read that it is the option that bear most with 3S, even one with 4s hehehe, also I will try with 11x6 Apc for 4S. Of course, first of all I will balanc the new prop. Moreover I will also use a dampened bed for autopilot.

I have not clear yet what to do with the motor mount, in hobbywireless charge me $ 13 for freight to Spain so do not know if I'm going to try some plywood mount. I have to study how to do it, I'm a little noob with this heheh
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Old Mar 04, 2015, 10:39 AM
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Canada
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Originally Posted by odnanref View Post
No, my prop wasnt balanced .
I have not clear yet what to do with the motor mount, in hobbywireless charge me $ 13 for freight to Spain so do not know if I'm going to try some plywood mount. I have to study how to do it, I'm a little noob with this heheh
Remembering just how badly balanced the stock prop was, that was probably the biggest mistake. It was likely enough to rattle the motor loose and when the prop hit the ground there wasn't enough strength for it to rotate out of the way.
On a pusher like this, the motor doesn't have to be mounted rock solid. All the propulsion forces push against the mount and it only has to be strong enough to hold fast when the prop drags momentarily on the ground on landing. Just make a plywood disc (1/4" thick) about the size of the stock mount and epoxy it over top of the stock mount if you don't want to dig it out of the foam. Drill a big hole in the center of the disc and a slot for the wires to go through. Use blind nuts and bolts if you're worried that screws may pull out.
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Old Mar 05, 2015, 03:48 AM
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Originally Posted by xviper View Post
Remembering just how badly balanced the stock prop was, that was probably the biggest mistake. It was likely enough to rattle the motor loose and when the prop hit the ground there wasn't enough strength for it to rotate out of the way.
On a pusher like this, the motor doesn't have to be mounted rock solid. All the propulsion forces push against the mount and it only has to be strong enough to hold fast when the prop drags momentarily on the ground on landing. Just make a plywood disc (1/4" thick) about the size of the stock mount and epoxy it over top of the stock mount if you don't want to dig it out of the foam. Drill a big hole in the center of the disc and a slot for the wires to go through. Use blind nuts and bolts if you're worried that screws may pull out.

Many thanks for the instructions, I was so lost on how to make wooden mount, now I think I got clearer . I just ordered an APC 12x6 propeller, when I get it, the first thing I will do is balance it hehehe. This weekend I'll get to work on the construction of the plywood, when I have made I will upload a few photos for you can give me your opinion, once again thank you for sharing your wisdom with me xviper
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Old Mar 05, 2015, 09:51 AM
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Canada
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Good luck. Remember that balancing a prop involves not only balancing the blades but balancing the prop hub. There are videos on YouTube that show you how to do this. Remember that even some of these FX's that fly on 3s, that prop can spin over 12,000 rpm. Those on 4s can spin nearly 18,000 rpm when a 1000 kv motor is used. Any imbalance gets magnified at those speeds.
And hand launched pushers with large props can be a health hazard if you're not well versed in such procedures.
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Old Mar 08, 2015, 04:31 AM
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Joined Apr 2009
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Hey guys, i just had my 2nd flight on the FX79 and noticed at high speeds around 90-100km/h the wing likes to nose drive by itself, i thought it maybe a thrust angle issue but it also seems to nose dive when the throttle is off when going quick. Ive got the CG set at the wing screws which is a little more forward then suggested, i tried to move the CG back to the suggested spot and made it worse. Any else had this or know why its nose diving ? My FX61 also does the same thing. Im running it on 4s so it has a bit more thrust and speed then 3s. Motor is Turnigy XP 3548 790Kv with 10x8 master airscrew prop
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Old Mar 08, 2015, 07:21 AM
hey whats burning?
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United States, FL, Vero Beach
Joined Oct 2007
818 Posts
Mine did the same thing but at lower speeds. Not sure why and it didn't do it all the time. It would randomly start to dive. It felt like the controller would start feeding in down, to confirm that wasn't the case I removed the flight controller and flew it with just the radio gear and nothing else and it still did it. I had HS65 servos so they should have been able to hold the surfaces. Never did figure out why and I ended up wrecking the plane trying to fix it. I would be interested in the your findings.
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Old Mar 09, 2015, 06:54 AM
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Australia, VIC, Berwick
Joined Oct 2013
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Quote:
Originally Posted by chris_p82 View Post
Hey guys, i just had my 2nd flight on the FX79 and noticed at high speeds around 90-100km/h the wing likes to nose drive by itself, i thought it maybe a thrust angle issue but it also seems to nose dive when the throttle is off when going quick. Ive got the CG set at the wing screws which is a little more forward then suggested, i tried to move the CG back to the suggested spot and made it worse. Any else had this or know why its nose diving ? My FX61 also does the same thing. Im running it on 4s so it has a bit more thrust and speed then 3s. Motor is Turnigy XP 3548 790Kv with 10x8 master airscrew prop
I believe this issue was reported earlier in this thread.
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Old Mar 27, 2015, 08:54 AM
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Originally Posted by jet72 View Post
mine should be ready for maiden on saturday
Any brand preference on the vinyl carbon wrap?
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