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Old Aug 01, 2010, 06:18 PM
It's over 9000!!!
Trexid's Avatar
San Luis Obispo
Joined Mar 2010
22 Posts
Quote:
Originally Posted by zmantaz View Post
Hey Trexid, anxious to hear of the results of the 720W motor. If it works efficiently, pulling verticals etc this might be a good alternative to the stock. What material is the black fins in the front inside of the cowl? Rather than remove it completely can't you use a dremel or something to open it sufficiently to support the larger C4250 800KV motor, or are there other variables involved?

I feel the 720 might be a bit underpowered, but we have to wait and see the results. I'm pleased that we at least have an alternative.
Well, I think I am going to purchase a more powerful motor. I was planning on using the 720 but I think ukgroucho and yourself are right that it is underpowered. I am going to shoot for a bigger motor/esc combo for this.

I just borrowed this motor from a friend to see how it fit and it will not work stock, the front cowl fins are made out of the same foam as the rest of the plane I don't think its EPO it seems like a little bit crunchier but very strong foam. Not sure.

At this point I am leaning towards something like this and then modifying the cowl / fins so this can fit through.
http://www.hobbyking.com/hobbyking/s...idproduct=4907

The comments and reviews on the product page give it some high ratings. Not sure if I will replace the landing gear right off. I'll probably fly it with those until I run into issues. Eager to hear about fatloser's maiden report from today!
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Old Aug 01, 2010, 08:17 PM
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Stratford upon Avon
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I think it may fly on the 720.. but it will feel lacklustre, like a high wing trainer - it will fly but not be particularly aerobatic.
My caveat is that the stock motor may be horribly inefficient when it pulls 1000 watts and then the extra 33% power drain is irrelevant.
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Old Aug 01, 2010, 09:58 PM
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Adams, Wisconsin
Joined Apr 2010
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Well guys no great news today from me. My day started w/ my daughter shaken the table it was on for pre-flight and broke the rudder. The plane was lite in the nose so i landed in the grass to make adjustments and broke my wood prop. I waited alday for my brother/camera man and he never showed up. I did do a engine test on the ground 3/4 throttle for 5 min and no problems. Motor was hot to the touch, but did not burn me. I'm definately going to run the stock motor until it goes. If your worried bout your cowl just fly w/o it until you see how she is going to last. Sounds to me some guys are fine w/ stock engine. I'm going to order a new wood 14x6 prop and add some weight up front. Probably a 3 to 4 min flight with half to 3/4 throttle and my pack only took 650 mah. Im going to make some adjustments and try to fly again with the plastic prop until i get it flying good. Good luck all... and i will post again when i get time to try again!!
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Last edited by fatloser; Aug 01, 2010 at 10:09 PM.
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Old Aug 02, 2010, 06:16 PM
It's over 9000!!!
Trexid's Avatar
San Luis Obispo
Joined Mar 2010
22 Posts
Quote:
Originally Posted by fatloser View Post
Well guys no great news today from me. My day started w/ my daughter shaken the table it was on for pre-flight and broke the rudder. The plane was lite in the nose so i landed in the grass to make adjustments and broke my wood prop. I waited alday for my brother/camera man and he never showed up. I did do a engine test on the ground 3/4 throttle for 5 min and no problems. Motor was hot to the touch, but did not burn me. I'm definately going to run the stock motor until it goes. If your worried bout your cowl just fly w/o it until you see how she is going to last. Sounds to me some guys are fine w/ stock engine. I'm going to order a new wood 14x6 prop and add some weight up front. Probably a 3 to 4 min flight with half to 3/4 throttle and my pack only took 650 mah. Im going to make some adjustments and try to fly again with the plastic prop until i get it flying good. Good luck all... and i will post again when i get time to try again!!
Yikes! Sorry to hear it dude. Ahh I see well maybe I will have to do some testing on the stock motor on the ground to see if I can get it to blow up before I do any flying on it. I'm still waiting on my 4S battery from HK to come before I can fly though. Maybe I'll run some 3s 2200 mAh's through it tonight and see how it does lol

Thanks for the report dude! I'll keep updating this thread as I get closer to my maiden
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Old Aug 02, 2010, 10:07 PM
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Caribbean
Joined Jul 2010
68 Posts
Woo hoo - that TURNIGY 50-55B 600kv Outrunner looks like plenty power for the yak. I think this, with a higher amp ESC would invariably turn this bird into the monster it is so named. Now, if you could only make it fit. The extra weight of the motor together with a heavier battery (4000-5000mAh) might put the CG spot on. I hear it is a bit tail heavy with the stock. I have not ordered my yak yet but plan to soon.

Keep up the good work of sharing guys, I'm sure in the end we would have a solid and capable "monster" second to none.
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Old Aug 03, 2010, 01:05 PM
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Lyon FRANCE
Joined Oct 2009
7 Posts
YAK 54 With KDA36-12XL

I have just made the first flight with my YAK 54
and the brushless motor burned.
I have just replaced the brushless motor by a KDA36-12XL
http://www.unitedhobbies.com/unitedh...idProduct=4657
it is assembled perfectly well has the place
Tomorrow I make the tests of flight with a new motor
excuse my english i am french
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Old Aug 03, 2010, 01:25 PM
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Xpress..'s Avatar
Joined Oct 2007
20,928 Posts
NEED VIDEO!!!!!!!!!!!!!!!!!!!!!!!!!

I wanna see how it does in the air...
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Old Aug 03, 2010, 02:57 PM
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Originally Posted by Xpress.. View Post
NEED VIDEO!!!!!!!!!!!!!!!!!!!!!!!!!

I wanna see how it does in the air...
1+ !!!!! Its worrying how many are having motors burn out to be honest !
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Old Aug 03, 2010, 03:32 PM
Dirty low puller
GHFlyer's Avatar
Ontario
Joined Apr 2010
31 Posts
Do not fly with the stock motor. It is over propped/underpowered. IT is rated at 800w but pulls +1000w on stock setup(as I have read). It may work fine for belly flying, but this is a 3D machine, and for those of us who like to slap it around, it will fail rather quick. I have ordered the same motor as jackalex69. I hope his flight review is good as I am tired of replacing RTF gear. Shame on HK for this ....but I'm sure we're all used to that by now. After 3 orders and shipping, this plane is no longer a value. BUT, I still look forward to flying it...again as it was a blast for the limited flight time I had. Should get my order any day and I will post some video. Don't be worried about burnt motors, just be worried about companies that sell sub par gear and risk our investments. Maybe we should go back to kits.
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Old Aug 03, 2010, 08:16 PM
It's over 9000!!!
Trexid's Avatar
San Luis Obispo
Joined Mar 2010
22 Posts
New Motor on the way!

Just placed my order today for my replacement motor with express shipping! I don't think I will be RTF by Saturday unless they can get it to me from China by Friday night lol

TURNIGY 50-55B 600kv Outrunner (Eq.4120/14)

Turnigy Brushless ESC 85A w/ 5A SBEC (This was the only Turnigy 80A+ ESC in stock)


And a whole assortment of different size props to play with and put on the meter...

13x10E TGS
11x10E TGS
12x6E APC
14x8 Master Airscrew
14x10 Type A Beech
14x7 APC
12x8 JXF
14x6 Master Airscrew

And these were on sale for a nice price so I snagged one of them as well..

ZIPPY Flightmax 3000mAh 5S1P 20C

This should get my Yak of the ground nicely I'm thinking

Now we play the waiting game...
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Last edited by Trexid; Aug 03, 2010 at 08:25 PM.
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Old Aug 04, 2010, 02:34 AM
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Stratford upon Avon
Joined Jul 2004
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Not had chance to fly mine again sine messing with servo horns etc. But I am starting to worry about the motor situation.

I was thinking that this http://www.unitedhobbies.com/unitedh...er_M%283530%29 might be a good fit.
Only 600Kv but I think that is probably appropriate with a 14" prop
Looks like the standard ESC will be good to go - no-one seems to have had an issue with that.
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Old Aug 04, 2010, 07:25 AM
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Lyon FRANCE
Joined Oct 2009
7 Posts
Hello
I have just made the test with motor KDA36-12XL
after 5 minutes of flight, the same motor blocked and burned.
I think that the problem come from ventilation, not of exit sufficient for the evacuation of the hot air.
I will make a large hole in the engine cowling in bottom.
Damage they was 5 minute of happiness
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Old Aug 04, 2010, 09:46 AM
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Darn that's bad. I must confess I did wonder if that motor was under-spec for the Yak... peak amps of 4S is only 28 amps.

You may have been pushing it a bit too hard

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Old Aug 04, 2010, 10:08 AM
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Lyon FRANCE
Joined Oct 2009
7 Posts
Over the 5 minutes, 4 minutes full throttle with flight slices.
It flight super and planes very well. 2 times to pose without motor and not breakage.
The propeller east can be a little large ????
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Old Aug 04, 2010, 11:38 AM
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Stratford upon Avon
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I think Hobbycity suggest an 11x7 prop to keep within the advertised amp rating. stock one shipped with the Yak is 14x7 ... that's a lot of extra amps.
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