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Old Mar 07, 2007, 02:36 PM
SB-28 UK Display Pilot
GeeW's Avatar
ENGLAND
Joined Jul 2001
2,461 Posts
Hi guys
Well after two weeks of dreadfull weather I finally managed to test fly my E-Uhu. Very impressed with the overall performance....even more impressed as its a foamie.
The "build" was a non event that I just managed to make last two short evenings...the third evening I spent painting the canopy, wing-tips and tail.
Motor + prop + ESC are stock
Jeti5 Rx
Battery 2 cell 1500 Lipo
Alti2 logger also on board. (extra 9gm weight)

First flight lasted 35 odd minutes with numerous climbs in 10mph gusty wind conditions....a couple of small broken patches of lift worked a little.
toatal capacity put back in battery was 1360mAh.

From the logger info (see below) the climb that passes through the 20 minute line achieved an average rate of climb of 390 feet/min which I thought fair enough.
Roll on the better weather
Best Regards

Gordon
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Old Mar 07, 2007, 03:12 PM
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Aberystwyth, UK
Joined Sep 2004
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Good to hear your happy with the UHU ( looks good in that paint scheme ). I flew mine a couple of weeks back on the slope in 25mph+ winds. The UHU performs really well in this dept.
Got some great vid, just need the time to edit it up and upload it.

Mark
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Old Mar 30, 2007, 03:37 PM
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Buckingham, England
Joined Aug 2005
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Hi Guys
I have just flown my Elektro UHU for the first time this week. It is a perfectly standard set up using a Flightpower 2s 1800 lipo. I normally fly ic (current planes Black Horse Speed Air and 3Styla) and I am just begining to explore aerobatics. However, I wanted a plane to fly in a 'set aside' field near where I live - something that could be landed in long grass. The UHU fits this requirement perfectly. It is very easy to fly in standard form.
One question for others in this group - I notice that under power it climbs steeply and requires a lot of down elevator. I am afraid of an upward zoom stall, especially when launching. When the power is low it glides beautifully more or less neutral on the elevator. The thrust line looks OK - difficult to go wrong anyway its moulded in. The lipo might be a bit heavy but surely that should keep the nose down.

Perhaps they all do this and I should just accept it.

What do you guys think? I would be interested hear flying experiences from the not so advanced fliers out there too. Thanks
Crashard
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Old Mar 30, 2007, 03:42 PM
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Aberystwyth, UK
Joined Sep 2004
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Quote:
Originally Posted by Crashard
Hi Guys
I have just flown my Elektro UHU for the first time this week. It is a perfectly standard set up using a Flightpower 2s 1800 lipo. I normally fly ic (current planes Black Horse Speed Air and 3Styla) and I am just begining to explore aerobatics. However, I wanted a plane to fly in a 'set aside' field near where I live - something that could be landed in long grass. The UHU fits this requirement perfectly. It is very easy to fly in standard form.
One question for others in this group - I notice that under power it climbs steeply and requires a lot of down elevator. I am afraid of an upward zoom stall, especially when launching. When the power is low it glides beautifully more or less neutral on the elevator. The thrust line looks OK - difficult to go wrong anyway its moulded in. The lipo might be a bit heavy but surely that should keep the nose down.

Perhaps they all do this and I should just accept it.

What do you guys think? I would be interested hear flying experiences from the not so advanced fliers out there too. Thanks
Crashard
The UHU will climb under power. The Easystar does the same thing. Only real option is to have a little throttle and elevator mixing or just hold a little down elevator under power.

Mark
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Old Mar 30, 2007, 05:39 PM
SB-28 UK Display Pilot
GeeW's Avatar
ENGLAND
Joined Jul 2001
2,461 Posts
Crashard
i don't know where you've got the C of G. I would recommend taking it back to about the rear limit as recommended. This helps but does not eliminate the nose up with power. Having said that once established in the climb I rarely have to give it a push to keep things nice, probably about 4 or 5 clicks of elevator trim between climb and normal glide. I would recommend not exceeding the aft limit as at high speed it tends to want to tuck gently, easily recovered with elevator but disconcerting!
My best flight to date 47 mins with only 3 1/2 mins motor time. Four flights over 40mins........not bad in 7 flights total!
Shortest flight 18mins, very windy and turbulent conditions, gave up long before the battery expired.

Have fun

Gordon
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Old Mar 31, 2007, 04:54 PM
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Buckingham, England
Joined Aug 2005
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Mark & Gordon
Many thanks for your comments and advice. I will try the throttle and elevator mixing first. I'll leave trying moving the c of g back until full effects of mixing ahve been explored. It might be rather difficult without using a lighter lipo. Having just spent nearly 30 quid on a flightpower you will understand my reluctance... Hopefully the winds will drop a bit later this week and I'll be able to fly.
Thanks Crashard
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Old Mar 31, 2007, 06:17 PM
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If you move the CG back your making the plane lighter in the nose which will make it climb much more under power. Best have the CG to far forward than back.

Mark
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Old Apr 01, 2007, 02:30 AM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by MarkJayne
If you move the CG back your making the plane lighter in the nose which will make it climb much more under power. Best have the CG to far forward than back.

Mark
Sorry Mark, but if your plane is nose heavy, you need up elevator to compensate in a glide. With motor on, the model will climb, because te elevator is not in neutral position.

Moving the CofG too far back however, will make a model more unstable, up to the point where it will become uncontrollable.

Jürgen
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Old Apr 01, 2007, 02:43 AM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by Crashard
Mark & Gordon
...
It might be rather difficult without using a lighter lipo. Having just spent nearly 30 quid on a flightpower you will understand my reluctance...
Thanks Crashard
You don't need another battery. A few grams of lead in the tail move the CofG back by a big margin.

Jürgen
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Old Apr 01, 2007, 02:47 AM
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Aberystwyth, UK
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Quote:
Originally Posted by Jurgen Heilig
Sorry Mark, but if your plane is nose heavy, you need up elevator to compensate in a glide. With motor on, the model will climb, because te elevator is not in neutral position.

Moving the CofG too far back however, will make a model more unstable, up to the point where it will become uncontrollable.

Jürgen
I agree Jurgen, but you will only hold a little up elevator on the glide, you can let it go under power ( although this does cause extra drag ). I rather hold a little up elevator at slower speed than hold a lot of down elevator at full. This is why I mentioned the throttle-elevator mixing, it works well on the Easystar although I have yet to try it on the UHU. Either way your not going to have the model fly level on both full power and on a glide without some sort of Elevator input, you have to compensate a little, and a little extra weight in the nose helps a lot in my experience.

Mark
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Old Apr 01, 2007, 04:27 AM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by MarkJayne
...
Either way your not going to have the model fly level on both full power and on a glide without some sort of Elevator input, you have to compensate a little, and a little extra weight in the nose helps a lot in my experience.

Mark
A model like the E-UHU is not supposed to fly level at all power settings (with motor off it is next to impossible ).

If the CofG is correct and the model is trimmed for a nice glide, the model should climb at full throttle without without any trim changes. If your model is nose heavy or overpowered (or both ), you may need to apply down elevator to control the climb angle.

Jürgen
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Old Apr 01, 2007, 05:46 PM
SB-28 UK Display Pilot
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ENGLAND
Joined Jul 2001
2,461 Posts
Mark & Jurgen

Have you two finished yet? ;-)

As I was saying , bring the C of G back to about the rear limit as in the instructions to minimise trim changes between motor on and off. Add ballast at the nose or tail to accomplish this. As you open the throttle the nose will rise by an amount but not excessively (assuming you are on stock power).
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Old Apr 02, 2007, 12:36 AM
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Quote:
Originally Posted by GeeW
Mark & Jurgen
...
As I was saying , bring the C of G back to about the rear limit as in the instructions to minimise trim changes between motor on and off. Add ballast at the nose or tail to accomplish this. As you open the throttle the nose will rise by an amount but not excessively (assuming you are on stock power).
I fly with the CofG exactly in the middle of the recommended CofG range. CofG position is sometimes a matter of personal preference, but moving it all the way back, might not provide enough stability for a beginner.

Jürgen
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Old Apr 02, 2007, 02:36 AM
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And I fly it with the CG at the most forward position

Mark
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Old Apr 05, 2007, 05:39 PM
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Buckingham, England
Joined Aug 2005
13 Posts
Hi again
Many thanks for your interesting comments on the power on/off trim. The weather in the South Midlands of England was just beautiful today - about 17 degrees sunny and with the gentlest of breeze. So it was off to a local set aside field to get a flight in. I spent 20 minutes cruising around the sky doing circles eights and turns - all very easy. I couldn't get much speed up though so I 'll need more confidence to get the UHU really high for a decent dive. Trouble is my eyesight never much good when I was young isn't that brilliant nowadays. I landed gently in long grass at the end of a long glide in. Bootiful!!
For next flight I am going to increase the control surface throws especially the rudder as I rather doubt if I could keep it into the wind if gets stronger than about 10 knots.
A great little plane for park flying.
Have some great flying this weekend chaps. (OOps and ladies of course!)
Crashard
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