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Old Jun 12, 2012, 03:25 PM
Registered User
United States, PA, Catawissa
Joined Jul 2011
353 Posts
I'd like to recommend you guys not to follow the factory recommended cg for any Techone planes. It seems like techone tend to set their planes slightly nose heavy. Flies good for beginners but kinda defeat its purposes as 3D planes. But thats just my opinion. I can be wrong, but i stand corrected
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Old Jun 12, 2012, 03:27 PM
Registered User
United States, PA, Catawissa
Joined Jul 2011
353 Posts
As for the stock plywood firewall, soak it with thin CA glue to make it stronger
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Old Jun 12, 2012, 07:48 PM
SoCal fair weather flyer
Bloosee's Avatar
United States, CA, San Diego
Joined Jan 2012
2,055 Posts
Yep I hear you all, 3 times broken motor mount on my 35 inch Yak, and yes the CG in the manual is way too far forward. I set mine up with a bunch of lead in the nose to get it as the manual stated. Now after 50 flights I realize that I've pulled most of the lead out and if flies perfectly neutral, and WAY better. CG must be a full inch behind the rear most recommended in the manual. AND now that it's not nose heavy I don't nose-in and break motor mounts!
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Old Jun 24, 2012, 03:19 AM
FOAMIES ROCK MR. BILL
williamleelewis's Avatar
United States, TN, Gainesboro
Joined Apr 2011
91 Posts
I can't decide which one to buy, the swift or the 43" yak or the su-31?
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Old Jun 26, 2012, 05:44 AM
Registered User
Huesca, Spain
Joined Aug 2009
494 Posts
I joined this club today.

Got myself a Pulama for cheap. looking forward to building and flying this cute little bipe.

Steve.
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Old Jun 26, 2012, 10:54 AM
Registered User
United States, PA, Philadelphia
Joined Dec 2011
2,136 Posts
Pulama is a nice little flyer! Again, the recommended CG is nose heavy. After some repairs in the nose, the battery compartment in mine became useless since I need to stuff the battery all the way back.
Also, take your time on the build with Welders glue only.. I am impatient so I used thin CA and accelerator on hinges, CF struts, etc. The EPP foam surrounding the glue became very brittle and got torn by the wind while flying outdoors, but you can always glue them back 100 times without affecting how she flies! It's fun to watch her fights against the wind.
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Old Jun 26, 2012, 03:03 PM
Registered User
Huesca, Spain
Joined Aug 2009
494 Posts
Thanks for the reply Vince_TT.

The advice re not using CA seems sound, I was thinking of UHU por.

Can you recommend a good starting point for the CofG that doesn't result in a nose heavy plane with the remit that I'm not looking to be flying 3D just yet either. I would like to start off by flying the model as a slow gentle aerobatic sporster and then move on from there.

Steve.
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Old Jun 26, 2012, 04:13 PM
Registered User
United States, PA, Philadelphia
Joined Dec 2011
2,136 Posts
I will measure mine tonight. I think mine is about 1/2" after the recommended CG.

Need to keep her as light as possible. My original setup was, C20 1550KV, 10A ESC, 2S 500 ~800 mah batteries, GWS 8x4DD, 5g servos on the tails and corona 9G MG on the ailerons, no landing gears, and she flew beautifully. Even if I use bigger (2s 1000) batteries, BTW which is totally not necessary , she still was under 300 gram. Later on my friend's kid nosed her in, burned the ESC and broke the depron inner structure at the front. I put a 18A ESC in and use EPO to rebuild the fuselage. She is about 315gram now. 8x4 won't give her full vertical so I have to use 8x6SF that requires close attention on overheat problem. In addition I need to stuff the battery fully under the wing to achieve my preferred CG location. Anyway, still a fun plane to fly and attract lots of attention in the school yard. Actually once I ran out of battery and landed her near the playground. An eight-years-old girl sprinted over, grabbed the wing tip and ran away. She tore the wing support and aileron....but what can you do?
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Old Jun 26, 2012, 10:58 PM
Registered User
United States, PA, Philadelphia
Joined Dec 2011
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Steve, my CG is 85mm back from the very front point of the top wing, about 5mm back from the CF spar and 10mm back from the recommended CG. I think you can start right at the spar.
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Old Jun 27, 2012, 04:14 AM
Registered User
Huesca, Spain
Joined Aug 2009
494 Posts
Vince,

Thanks very much for the details.

This is my planned set-up:

2204/14 motor-19g, 8x4 prop, 10A esc-10g, Rx-5g, servos-2x6g, 1x8g.
Lipo-3S 800mah 20c - 60g, or 2S 800mah 20c-46g

With everything loaded onto my scales I get a total 195g without battery. So, should be a nice light model even on 3S.

Steve.
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Old Jun 27, 2012, 11:00 AM
Registered User
United States, PA, Philadelphia
Joined Dec 2011
2,136 Posts
2204 seems a bit short in the length. did you dry fit the motor on the firewall yet? Never try 3S in this class, don't know if the 10A ESC can handle that. But I am sure it would be lots of fun!

Went through 3 packs on my Yak 54 in high wind late afternoon yesterday, decided to get rid of the landing gear for good. Actually no coupling issue at knife edge after removing the LG. The color scheme of the Yak became hard to originate near dusk, so I have some hair moment at rolling cycle. Still cannot do a pop top or a nice flat spin yet, having trouble finding the correct timing. Anyone can share some tips?
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Old Jun 27, 2012, 11:11 AM
WickedFunRC's Avatar
Utah USA
Joined Jun 2002
2,210 Posts
2204/14 motor is a blast on 3S. But you want to run a 7x3.5" prop, the 8" is too much for it.
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Old Jun 28, 2012, 10:31 AM
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LawnDartMike's Avatar
United States, OR, Salem
Joined Jan 2012
286 Posts
For those with the 34" YAK, what COG and battery size are you running? After reading some of the posts here I'm thinking my COG is too far forward running the 1300 battery.
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Old Jun 28, 2012, 12:08 PM
epphobby's Avatar
United States, PA
Joined Aug 2011
321 Posts
Quote:
Originally Posted by LawnDartMike View Post
For those with the 34" YAK, what COG and battery size are you running? After reading some of the posts here I'm thinking my COG is too far forward running the 1300 battery.
I run 800mAh battery on the 34 Yak. With stock setup and without any modifications, AUW will be on the heavy side and it will become nose heavy with 1300 inside the battery slot.
IMO, Techone recommended CoG tends to be on the nose heavy side for 3D setup.
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Old Jun 29, 2012, 07:01 AM
Registered User
Huesca, Spain
Joined Aug 2009
494 Posts
Many thanks to you guys.

I realised that my proposed set-up for the Pulama wasn't hitting the mark, especially the ESC, which was rated at only 10A.

So, I have ordered a 20A ESC and will be using 2S 800mah 20C lipos. Measuring 60x30x15mm and 48g they are perfect for the battery hatch. I still plan on using the 2204/14 motor with an 8x4 prop.

Yes Vince, the motor is a bit short, about 10mm. I will construct a new firewall further forward and attempt to mount it with both down and side thrust built in.

Steve.
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