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Old Jan 17, 2011, 02:34 AM
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Sorry, dupicate post. Pleaase see: http://www.rcgroups.com/forums/showp...&postcount=525
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Old Jan 17, 2011, 02:36 AM
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Ljubljana Brnik, Slovenia
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Sorry, dupicate post. Pleaase see: http://www.rcgroups.com/forums/showp...&postcount=525
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Old Jan 17, 2011, 05:38 PM
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Mitja,
thanks for your extensive report. It seems that one really needs a lots of practise and experience to get things flying. well, will see.

Mine fuselage can be found here:

https://belohrad.web.cern.ch/belohrad/DSC01788.JPG

i have to admit that it was quite a lot of work, and at some places it is screwed. But i take it as a tax for getting the experience.

One thing, which is not discussed much here is the covering tutorial. Especially how you and others made the covering composed of multiple colours and their combination. Is there some trick to position the stripes of foil correctly and avoid that it displaces under shrinking process?

(btw: i'm from CZ)

thanks again
d.
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Old Feb 22, 2011, 07:19 AM
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Dear All,
i report partially successful maiden flight, you can see some videos here:

first start goes badly:
Guppy Flying test (0 min 22 sec)


second attempt:
Guppy Second Fly (0 min 58 sec)


Now, the thing is, I have to say that the first flight was wrong just because I did not check whether the rudder and elevator go correct direction. Rudder needed to be reversed and that's the reason why the plane fell off.

However in the second fly is visible some vertical instability I cannot explain for the moment. The CG is +- correctly setup as it should be, and the plane has tendencies to stall even in slight wind, and when running on the motor, it rises up quickly and then it stalls. So the flight is somehow waving and it takes lots of effort to keep the plane on-track.

Any ideas?

thanks
d.
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Old Feb 22, 2011, 09:27 AM
Circa:1946
Riverratss's Avatar
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Maiden

Mr. dejfson!

Might try a little more forward COG!
See how you like it?
Just my .02cts.

Regards!
Jimmy
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Old Feb 22, 2011, 10:12 AM
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less throw on the control movement.
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Old Feb 22, 2011, 02:13 PM
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Hand Launch!

Quote:
Originally Posted by bfry View Post
less throw on the control movement.
Definitely concour bfry!!!!!!!!!

I like to hand launch griping the fuse below COG, & throwing out at a slight down angle!!!

Regards!
Jimmy
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Old Feb 22, 2011, 03:59 PM
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not sure what you mean by 'less throw on the control movement'. shall i just 'release' the plane from my hand and let it handle the stability itself?
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Old Feb 23, 2011, 05:52 AM
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Are the wing and tailplane set at zero degrees incidence, I.e. Are they parallel? If not and there is negative incidence then it will always want to stall as it is like having permanent up elevator applied.

When on full throttle you will either have to hold some down elevator in manually or if you have a computer tx you can mix some down in with the throttle so it climbs without stalling.
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Old Feb 23, 2011, 08:45 AM
Circa:1946
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Control Surface!

Quote:
Originally Posted by dejfson View Post
not sure what you mean by 'less throw on the control movement'. shall i just 'release' the plane from my hand and let it handle the stability itself?
Mr. dejfson!

I think what bfry was saying is that your control surface travel is extreme!

Rudder-25MM L&R from zero measured at widest part of rudder.

Elevator-10MM U&D from zero measured at center of elevator.

Regards!
Jimmy
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Old Feb 23, 2011, 09:31 AM
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I see i see now guys.

I'll try to get it running during the week-end
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Old Feb 23, 2011, 09:37 AM
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I have good luck with even a little less than the "factory" spec. on most planes.
It will help you not over control the plane. Give it a whirl.
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Old Feb 27, 2011, 09:39 AM
Circa:1946
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How did it go?

Quote:
Originally Posted by dejfson View Post
I see i see now guys.

I'll try to get it running during the week-end
Mr. dejfson!

Did you get to fly?

Regards!
Jimmy
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Old Feb 27, 2011, 01:21 PM
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Quote:
Originally Posted by Riverratss View Post
Mr. dejfson!

Did you get to fly?

Regards!
Jimmy
I've tried second time. This time however:

1) i've changed CG. I found that the airplane was tail heavy, so by putting (quite a lot of) some material I've managed to get it where it was supposed to be according to planes

2) i've changed the end points to both ruder and elevator to conform with what is in the plans

... and then tried ...

It was much better that the first time, the plane stalls much less, however there is still some fancy behaviour when turning left/right. The plane has tendency to be quickly vertically, and once it is vertical (the wings are verically wrt ground), it points nose down and quickly drops. This can be avoided by not turning so aggressively, so maybe rudder trimming even more (now i'm at 30% on both end points) would help

I think however that combination of motor (XM2826) is definitely not very fancy with 6x3.5 foldable propeller (originally used with speed400 motor in drawings). Although the motor should have enough power (150W?), there is quite a lot of power lost due to mismatch with propeller, which - for this engine - should be somewhere around 7.5x4.5 or 8x5 (??).

This results in very small drag, so if the plane does not catch wind directly during hand launch, it drops to the ground almost like a stone.

And well, this is exactly what happened. So during my third or fourth fly the plane just dropped, nose down, propeller broken... have to order another one, but this time i'm rather thinking to order 8x5 foldable than original 6x3.5.....

i'm not sure whether this helps or not, but i guess this could be the way to go...
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Old Feb 27, 2011, 08:45 PM
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Guppy

dejfson!

I thought from the video the plane looked to be under powered.
Also tail heavy!
Keep going you will get it sorted out!

GOOD LUCK!!!!!!

Regards
Jimmy
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