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Old Oct 13, 2007, 09:34 AM
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Quote:
Originally Posted by BrunooO
Ok malves,
I will wait the new version, when u fly it tell me if the plane is better than the other version and post the plan
Daniel Z, here in brazil I have this motor or one motor that weights 9g and for 7" propeller max. it gets about 150g of thrust and i will need to make the plane with 70g!
So, i prefer to use the hextronic motor
Will do, man. A 9g motor would be better for the smaller version. I use the A10 which is 14g and also turns a 7" prop. If you use a light setup - light servos, receiver, 2s 300-350mah packs - you'll definitely be around 105-110g or maybe less, depending on your building. 150g of thrust would be enough for full 3D flying at that weight level.
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Old Oct 13, 2007, 11:14 AM
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BrunooO's Avatar
Brasil, São Paulo, Lins
Joined Jul 2007
97 Posts
Malves, I think I will use thisconfiguration...What do u think??
Motor and Esc:http://www.rctechshop.com/loja/produ...roducts_id=461 (but I will use this batery http://www.rctechshop.com/loja/produ...roducts_id=343 )
3.3g servos: http://www.rctechshop.com/loja/produ...roducts_id=452
And a bLue arrow rx 2.8g: http://www.100aero.com/product_info....products_id=72
The problem is that i have only the 4mm depron ,
So I think i´ll reduce the plan to 25" What do u tHink??
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Old Oct 13, 2007, 11:45 PM
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Joined Jun 2004
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Just got back home. Another great night at the gym. Met Birdie-in-Texas again and his wonder toolbox that save me again, after I hit the floor and my motor came off from the nose.. So, there was another guy flying 3D and the 3 of us are talking. I asked about the guy's motor and it was a very VERY nicely wound cd-rom motor. But I noticed something else. The way the motor was mounted looked familiar. Could it be Fwilly? But wait! Fwilly doesn't live in TX, right? Right, but he drove from New Mexico...and I was pleasantly surprised to meet him.
The longer Yak flew very nice. It came in at 4oz. I bought 2mm depron by mistake. I have a short vid flying it that Birdie shot. I'll try to post it tomorrow. It will show how much class I have when I crash.
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Old Oct 14, 2007, 09:21 AM
Pro Bro #495
fwilly's Avatar
Farmington NM
Joined Apr 2002
3,194 Posts
It was great meeting you, Malves!!

Your Yak sure looked like it flew great
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Old Oct 20, 2007, 01:25 PM
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nishuko's Avatar
Lithuania
Joined Mar 2005
7 Posts
Hi, the summer past and I had some time to make my rew for this amazing plane .
Rx Dynam 5ch
2servo Gws pico 5.4g (on elevator and rudder) and JR es375 (on ailerons)
Akku: (only 2cell for this model) 450mah 15c and 820 10C for outdoor
ESC : Fly 12A/15A
"Vytas engine"
It can do all 3D manoeuvres, but not so good for knife edge (it needs some speed for this), very good for hovering ( I was doing it in my liveing room when it had been raining outside).

Actually this is my first painting job
More: http://rcunderground-nishuko.blogspo...ne-to-fly.html
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Old Oct 21, 2007, 04:31 AM
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richard boyd's Avatar
Northern Ireland
Joined May 2006
1,212 Posts
I love the paint job its cool . Is this your first yak , i have an ikarus yak and knife edge is good . I kept it light and add a little more rudder area and it helped he knife edge speed .

Richard
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Old Oct 21, 2007, 05:21 AM
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Lithuania
Joined Mar 2005
7 Posts
Thanks Yes, it's my first Yak, it was built for f3p B practising, but it was also very good for 3D. I'm going to build one for pure indoor.
Now I am flying with Futurion which requers only a little touch of rudder (actually knife edge is easer when normal, horizontal, flying ), maybe I shouldn't compare the perfomance of these two different planes...
So for the other Yak I'll increase ailerons and rudder (as you did), it should perform much better then.
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Old Oct 21, 2007, 03:05 PM
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Northern Ireland
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I also fly Futurions and they are the best plane for my style of flyin . Yaks are very good as we all know derk has proven this , i am flyin a Future to learn F3p and it is so easy , i look good but im far from it . Knife edge is effortless no imput is required slow up lines and slow down lines . The future is not an easy build but when you take time and make sure everything is equal and set the radio gear in correctly then the rewards are a true flying model that makes a bad pilot look good .
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Old Oct 24, 2007, 08:21 AM
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Joined Jun 2004
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Quote:
Originally Posted by nishuko
It can do all 3D manoeuvres, but not so good for knife edge (it needs some speed for this), very good for hovering ( I was doing it in my liveing room when it had been raining outside).
Plane looks great, bro. I understand KE has some coupling, but I KE mine at slow speed with little rudder and I just mixed the coupling out. The longer version I just built has less coupling during KE, thou.
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Old Nov 10, 2007, 01:49 PM
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BC Canada
Joined Oct 2005
82 Posts
Hi guys,
First time building my own foamy, I'm hooked. I was doing a search and came across your Yak, love it. I am a little stuck though. I have printed out the pages, cut them into templates, cut all the 3mm depron etc. I am trying to do a mock setup but my wings are too far forward. Can someone explain or post a picture so a rank newbie can build this

I am assuming the flat fuse piece butts up against the back of the wing and the front fuse piece butts up to the front of the wing?

My back flat fuse piece is just over 12.5 inches and my front is 3.75 inches

Help

How far from the front of the fuse to the LE
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Old Nov 11, 2007, 07:50 PM
KJ4IKY Gravity Wins
blade thrasher's Avatar
Georgia
Joined Apr 2007
840 Posts
6mm depron build

Using the plans here is what i have so far on this build. I added some foam for stability and used 3.5" floppy media as the hinges.

Right now its pulling 3.2 A and 30W at full throttle from a 2S 850mAh on the 2500kv Turborix.

Here is the motor details. Im trying to get the most thrust with 5-8 min flight times. Any ideas for the best prop size on this foamie?

MOTOR:
No. Of cells : 2-3 Li-Poly
rpm/v (kv) : 2500
Propeller : 5 X 3
RPM : 18000
Max. efficiency current : 7A
Thrust : 300g
Weight : 24g
Shaft diameter : 3mm
Dimensions : 18x10 mm
Max. efficiency : 89%
No load current : 0.9A/10v
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Old Nov 16, 2007, 01:55 AM
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BC Canada
Joined Oct 2005
82 Posts
Your nose came out as long as mine!
The others have a shorter nose. Have you flown it yet? How far back from the LE is your CofG

No one is helping me out
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Old Nov 16, 2007, 04:13 AM
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Ireland, Kildare, Leixlip
Joined May 2002
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Quote:
Originally Posted by blade thrasher
Right now its pulling 3.2 A and 30W at full throttle from a 2S 850mAh on the 2500kv Turborix.

Here is the motor details. Im trying to get the most thrust with 5-8 min flight times. Any ideas for the best prop size on this foamie?

MOTOR:
No. Of cells : 2-3 Li-Poly
rpm/v (kv) : 2500
Propeller : 5 X 3
RPM : 18000
Max. efficiency current : 7A
Thrust : 300g
Weight : 24g
Shaft diameter : 3mm
Dimensions : 18x10 mm
Max. efficiency : 89%
No load current : 0.9A/10v
I don't know the motor but I'd be VERY sceptical about those specs.
I don't for a second believe 89% efficiency from a 24g outrunner in actual operation at 7A. I'd be astonished if that were true and I think they'd have a lot of other manufacturers buying up their motors to figure out how it's being achieved. Also they're claiming 300g of thrust but they don't say on what cell count or prop which makes it meaningless. Motors don't produce thrust, propellors do. And you need sufficient pitch speed too if you want to make a plane fly.
I'm not saying there's anything wrong with the motor but I'm very suspicious of those specs.

Anyway, you want 5-8mins from a 840mAh battery. There's no max current spec so say we use the specified(!) max efficiency current of 7A.
Even loaded to 7A for the whole flight you'll get 0.84/7*60 = 7.2 minutes.
For this sort of plane to fly the way it should you'll want to be able to fly fine at half throttle or much less with full throttle providing lots of extra power only normally used for high drag manoeuvers or vertical climbs. So you'll probably get close to 15 minute duration depending on your flying style and AUW.

If you can measure current I'd suggest getting a GWS HD 6x3 and 7x3.5 for starters and aim to draw somewhere near the specified current. It may manage an 8x4 but I'd try the 7x3.5 first. A 2s 840mAh pack is going to mean the plane's not going to be terribly light and I'm not sure 7A on 2s is going to be enough for good performance but it's worth a try.

Aidan
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Old Nov 16, 2007, 06:05 AM
KJ4IKY Gravity Wins
blade thrasher's Avatar
Georgia
Joined Apr 2007
840 Posts
Suspicions verified

Quote:
Originally Posted by Aio_1
I don't know the motor but I'd be VERY sceptical about those specs.
I don't for a second believe 89% efficiency from a 24g outrunner in actual operation at 7A. I'd be astonished if that were true and I think they'd have a lot of other manufacturers buying up their motors to figure out how it's being achieved. Also they're claiming 300g of thrust but they don't say on what cell count or prop which makes it meaningless. Motors don't produce thrust, propellors do. And you need sufficient pitch speed too if you want to make a plane fly.
I'm not saying there's anything wrong with the motor but I'm very suspicious of those specs.

Anyway, you want 5-8mins from a 840mAh battery. There's no max current spec so say we use the specified(!) max efficiency current of 7A.
Even loaded to 7A for the whole flight you'll get 0.84/7*60 = 7.2 minutes.
For this sort of plane to fly the way it should you'll want to be able to fly fine at half throttle or much less with full throttle providing lots of extra power only normally used for high drag manoeuvers or vertical climbs. So you'll probably get close to 15 minute duration depending on your flying style and AUW.

If you can measure current I'd suggest getting a GWS HD 6x3 and 7x3.5 for starters and aim to draw somewhere near the specified current. It may manage an 8x4 but I'd try the 7x3.5 first. A 2s 840mAh pack is going to mean the plane's not going to be terribly light and I'm not sure 7A on 2s is going to be enough for good performance but it's worth a try.

Aidan
You were exactly right. That little POS couldnt deliver even half the thrust they claimed and it pulled almost 8.7A before it vibrated off the mount and took a chunk of depron from the nose and half the credit card mount with it.
I unglued it and mounted an old slow stick motor. Running an 1280 its pulling 6.4A. The specs say this motor should pull 12A with that prop? Of course my CG had to be moved even further back. My CG is now around 22-23 CM from the LE. Total flying weight with pack is 341g with the 850 mAh 3S. Hopefully the 15 mph winds we have had here in GA will die down and I can get a test flight on this thing.
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Old Nov 16, 2007, 06:19 AM
KJ4IKY Gravity Wins
blade thrasher's Avatar
Georgia
Joined Apr 2007
840 Posts
Quote:
Originally Posted by SaltySteve
Your nose came out as long as mine!
The others have a shorter nose. Have you flown it yet? How far back from the LE is your CofG

No one is helping me out
I actually made the nose 1.5" longer along with .75" wider chord and 1" longer span. I have no idea if these proportions will work but I wanted to fly with larger packs. This is my first foamie too so Im not going to be surprised if I bank straight into the dirt on the first go. The CG is now around 22.5 cm from the LE, loook at the photo above and you can see how far back I had to mount the pack. This is all from 6mm depron.

I think my next scratch build will be a larger fanfold foam body with big dihedral removable wings. I want something that can carry a camera for AP. All I need are some good large scale plans (with removable wing for transport) and a motor reccomendation for something that big.
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