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Old Sep 24, 2012, 07:02 PM
25+ years of RC flying
BigIron357's Avatar
United States, FL
Joined Aug 2012
1,490 Posts
Quote:
Originally Posted by makind View Post
I talked to the guy and he was swearing that he lunched the plane as straight as possible. He has other planes also and only this one had problems.
Is your friend launching the plane by himself or using a helper? I can't tell from the video, but it does look like he's wearing a GoPro or something and launching the plane alone. If that's true, have him get someone else to launch it for him and see if the same thing happens. (But check out the slow-mo video below... I bet the problem goes away with another person launching.)

As others have pointed out, that right aileron is warped a bit. It might have some effect but since it's warped up it should give a righthand roll moment, not the other way around.

Watch this video closely. You can see that his hand is imparting force to both the roll and yaw axes on launch and that the nose is well up and not straight ahead. It also looks like there MAY be some up elevator input, which could induce a stall rather quickly at that low airspeed.


VIDEO
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Old Sep 24, 2012, 07:17 PM
Rocket Programmer
jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
25,445 Posts
Tell him to try throwing it with the correct hand (and use a radio strap to hold the radio). Try it and let me know if it works then I'll tell you why
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Old Oct 19, 2012, 06:35 AM
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makind's Avatar
Australia, QLD, Morningside
Joined Apr 2011
142 Posts
Changed prop for 12x6 (bigger speed) and the plane fly very very good.

Unfortunately i forgot camera home, next time i will try to capture it.

Also ordered L3010 430w motor with 9x6 prop.


Definitely it was speed issue
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Old Oct 19, 2012, 08:37 AM
Canadian Bacon
flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
13,025 Posts
It was in a stalled attitude as soon as it left his hand. Probably would have flown fine had it been launched straight ahead. Down elev might have helped but not from that altitude.

Gord.
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Old Oct 20, 2012, 12:32 PM
buyer of the farm
United States, FL, DeLand
Joined Mar 2009
4,572 Posts
I'm afraid that plane was stalled before it ever left the hand. It was just a terrible hand launch. I wouldn't make any conclusions about plane setup based on that launch. It looked pretty normal and flyable to me.
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Old Dec 01, 2012, 09:56 AM
fly to the moon :)
aeroseb's Avatar
Canada, QC, Terrebonne
Joined Apr 2009
182 Posts
underpowered motor. The prop doesn't turn enough at the right speed to create good lift.
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Old Dec 01, 2012, 10:35 AM
buyer of the farm
United States, FL, DeLand
Joined Mar 2009
4,572 Posts
Uhhhhh.......props don't create lift unless they are mounted on the wing, and even then it is just a little lift. Unless the plane was GROSSLY overpowered like my Slow Stick, that launch guaranteed a crash, no matter what the pilot did. In normal circumstances, planes fly with their wings, not their motors.
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Old Dec 01, 2012, 11:50 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,961 Posts
Looks to me like it was seriously underpowered, it never had enough airspeed to even start flying... Prop on backwards maybe or maybe a bit heavy, plus wimpy hand launch?
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Old Dec 01, 2012, 02:56 PM
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alibongo's Avatar
United Kingdom, England, Dorset
Joined Apr 2010
973 Posts
Quote:
Originally Posted by JetPlaneFlyer View Post
Looks to me like it was seriously underpowered, it never had enough airspeed to even start flying... Prop on backwards maybe or maybe a bit heavy, plus wimpy hand launch?
All of that.Also,as makind says it can climb vertically, a bit of throttle should have got it away.
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Old Dec 01, 2012, 03:10 PM
buyer of the farm
United States, FL, DeLand
Joined Mar 2009
4,572 Posts
The problem with the underpowered theory is that the plane will fly when properly launched, even with the motor off. It will glide for some distance before it hits the ground because it just doesn't need the motor to fly, just to climb. However, in this launch the plane was an unguided rock. It never began flying.

Bad hand launch. Not enough info to make any other judgement about what might or might not be wrong with the plane.
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Old Dec 01, 2012, 05:36 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,961 Posts
Quote:
Originally Posted by Rockin Robbins View Post
The problem with the underpowered theory is that the plane will fly when properly launched, even with the motor off. It will glide for some distance before it hits the ground because it just doesn't need the motor to fly, just to climb.
That's true, providing the hand-launch is good.. It's probably a combination of a poor launch and being underpowered but as you say, the plane never even looked like even starting to fly.

As noted above, if it really did have the power to climb vertically then he would have got away with it... But clearly it didn't because when it put it nose up it just lost speed, stalled and fell out of the sky.
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Old Dec 01, 2012, 05:59 PM
Registered User
Wilson, NC
Joined Aug 2009
223 Posts
If the prop is mounted backward the prop thrust is reduced to about only 70%. Sometimes it is not obvious that the prop is mounted wrong.
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Old Dec 01, 2012, 09:01 PM
Registered User
United States, ID, Burley
Joined Mar 2012
3,354 Posts
Quote:
Originally Posted by rtbates View Post
Looks like he waited too long to start feeding in DOWN elevator. Was probably giving it up elevator the entire time and she stalled...

Throttle controls ELEVATION, elevator controls SPEED... unless ,of course, you have 1:1 or more thrust to weight..which he obviously did not
Also if it has not be mentioned, make sure the ailerons are trimmed level and trim in just a touch of up in elevator for launch
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Old Dec 02, 2012, 04:03 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,961 Posts
Quote:
Originally Posted by fastfwd View Post
Also if it has not be mentioned, make sure the ailerons are trimmed level and trim in just a touch of up in elevator for launch
If anything he had too much up elevator at launch, the nose came up as soon as it left his hand. Probably more to do with inadequate flying speed than anything else but for sure trimming the elevator more up would have been counter productive.
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Old Dec 02, 2012, 06:42 AM
Not always grumpy!!
insomaniac45's Avatar
UK, Eastleigh, Eastleigh
Joined Jul 2010
577 Posts
im a bit of a noob my self, but have tried to build a few models in the past, with mixed sucess. i have however noticed no one has said about COG?

it could just be too tail heavy, causing the rising nose, then stall.
a plane like this does need a bit of speed to generate stability from air passing over the wings.

I also suck at hand launching, but one way i have foubd that is dead easy, is to do it underarm. hold the fuse as near to the cog as you can, apply enough throttle until you feel her pulling nicly, then rotate your arm as if your throwing underarm, making sure you dont give that extra boost, but keep it steady. then slowly apply a little more throttle. this i have found to give me 100% success at hand launching (as long as the plane will fly)

best of luck

tony
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