bipeman-RCU

My Feedback: (16)

Hey Hog, I really think you have it backwards... sounds like a cheap ARF hardware failed causing the flutter, and subsequent loss of aircraft. No? Gears may have stripped due to high forces of flutter banging heck out of them.

Got my wing tube from CG. Happy - happy! Still finishing Composite ARF 33% Extra 330L but can't wait to get the Yak in the air! Going to be a great Fall flying season for me here in TX!

R/C Foolish

My Feedback: (6)

Nobody seems to pay attention to JR Sport servos. Futaba's are too expensive to even bother buying, all you read about is Hitec failures. I use JR 125 MG Sport servos, 125 oz. of torque with metal gears for $34.00, how can you go wrong and that is just with 4.8 batteries.

R/C Foolish

adrenalnjunky

My Feedback: (18)

Some of the threads on the JR sport 125's are less than favorable too. A lot of it seems to be runningthem on 6volt packs, but, oh well, my local shop quit carrying JR.

I own dozens of HiTec servos, and have never had a failure - not saying it doesn't happen, but until I have troubles, I'm not changing what I know and trust. Plus any Nylon/Resin gear servo would have stripped in the situation that stripped the HS635's in question.

Futaba's don't cost much more - basically you have 3 servos for a budget hi-torque MG servo out there -
HiTec 645/625 - ~$34 ea.
JR Sport 125 --- ~$34 ea.
Futaba 3305 --- ~$34 ea.

All are metal geared, all have at least 120oz/in torque on a 6.0v pack - Pick your favorite brand and enjoy.

rkingmanila

My Feedback: (1)

i have a CMP Katana which i have a Brison 2.4 on. I almost lost it too with the Hitec 635HBs that i put on the ailerons. gears stripped and fluttered. luckily i got it down in one piece. I wouldnt ever use Karbonite gears again on any plane larger than a 70 inch span. Lesson learned. I;m guessing hogs problem might have been due to the gears strippin on his 635 as well.

kempo

if you want your plane to hover well DO NOT USE O.S. 1.60 flys great but no pull out power if some one has the right combo let me know i want to change the 1.60 out and put the right engine in. i only want fax and not speculation.

dncmeloni

Kempo- Have you tried any different fuel mixtures with your OS 1.60.
You can swing a APC 18x6- 3d fun fly prop , 400 to 600 more rpm by adding two motor shims and going to 30%.
It will run a little cooler as well.
It might be worth a try.

Frag

When measuring the CG, did you measure under the wing right up against the fuse or out a bit laterally under the wing? There was an article in MA that was saying on tapered wings that the true cg would not be measured directly against the fuse but out a bit...[sm=confused.gif]

R/C Foolish

My Feedback: (6)

After many unhappy flights with my Evolution 35GT, I changed to a Brison 2.4. What prop are you guys with this motor using?

R/C Foolish

adrenalnjunky

My Feedback: (18)

20x8 Xoar on mine. And my Brison was Aerobob's, as I bought his Yak and brison that he started the thread with. He was running a different brand 20x8 on his.

adrenalnjunky

My Feedback: (18)

To all good things come an end, and unfortunately, in this case it is the end of the plane that Bob started this build thread with.

On the maiden of the plane after buying it from Bob, I managed to flutter the ailerons - and worse, it was my fault. Not a servo issue (single Futaba 3305) - it was me not getting the control horn screw tight enough on the aileron servos. Looks like they were able to back out (or were never tightened - now I can't be 100% sure) - and the DuBro HD control horns I used stripped all of their splines out. It might be possible the DuBro arms had some fitment issue that made me think I had the screws tight, and then allowed play - but no way to tell that now. Plane went in in the woods, and actually landed suprisingly well considering I couldn't see it for the last 100 feet or so. After trekking through the trees and thorns I found it sitting on the ground, shattered, looked like it flew through a stand of saplings. The nose broke clean off and only damaged the prop - the cowl would have been perfect if the prop hadn't folded back up into it - but the Brison and spinner are fine - so much for small miracles. Actually all hardware survived the crash - all servos were responding normally to the transmitter post mortem. Then to add insult to injury I put the wreckage in my truck and manage to get the rudder in a bind against the truck door - I was like "who cares - it's trash anyway." Well I get home and notice that my Rx swich had gotten bumped on somewhere in transit and now my rudder servo is locked up solid. Oh well one servo, one Xoar prop down - I'll probably buy another cause for the 1 minute I did fly it - it flew vey well. This time, I'll upgrade to some locking aluminum control arms I think.

EMVIN

adrenalnjunky.....My condolence's...........Welcome to the club......I lost mine back in the spring on the second flight..... since then I bought a QQ Somenzini YAk54 73".....Fantastic!!! ....EMVIN....

Frag

My maiden jitters have been renewed! It may be this coming Sunday....gotta check..EVERYTHING AGAIN[sm=spinnyeyes.gif]

EMVIN

AND AGAIN...........

adrenalnjunky

My Feedback: (18)

I wish you both the best. I just talked to Tower today - I have a new unopened CG Monster Pitts that I haven't started building yet, I'm shipping it back to get credit and order another Yak.

Kevin23

My Feedback: (4)

I just bought a cg yak 77" and was wondering if you guys thought a hobbico cs-70 servos would be ok in the elevator?

I'm asking because i originally had hitec 635's in there,and just after the maiden flight noticed one of the servo's had slop around center and found a stripped gear in the servo.

installed the cs-70's and flew it,then it started to fly like it was out of trim,the longer i flew it the worse it got,barely got it down and one of the cs-70's was fluttering and it lost it's centering.
I was hoping this is just a bad servo and not because the plane requires something bigger,just bought these friday[]

adrenalnjunky

My Feedback: (18)

The CS-70 is what I believe is basically a HiTec HS-625MG in disquise - I know the specs don't quite line up - but it does use the same replacement gearset. Maybe the 70 is the older HS-605 that the 625/645 replaced. I would think that either of these servos would work fine on this plane. I hope so, cause I'm running Futaba S3305's on mine, and they're in the same ballpark on torque. Generally, the elevator surface area isn't that terribly oversized for a plane this size - Iwould hope 125oz/in per side is fine. I would be more concerned about the Rudder since it seems very big in comparison to some other Yaks that are even bigger in wingspan/scale than this plane.

I'm thinking you either have a bad servo, or a bad extension - I have seen several HiTec servos that didn't want to center - actually oscillating around centher, that was fixed by replacing the extension.

Since I dumped my first Yak due to aileron flutter, I'm now very paranoid about how I'm setting up my replacement CG Yak. I finished the wings last night - now I'm using SWB double lock aluminum servo arms, and SWB titanium linkages. I'm still wondering if I should move up to HiTec Hs-5955 Digitals since I'm only running one servo per aileron.

Decisions, Decisions.

adrenalnjunky

My Feedback: (18)

That reminds me - I did seal the hinge line on the wing for the new Yak, but do I need to think about sealing the elevator and rudder hinge lines?

Frag

It may have been overkill but I did seal the hinge lines of the elevator and rudder with clear Ultrakote.

YakPak

Emvin
What engine did you put in the 73" Somenzini?
How does it perform?
Thanks
YakPak

EMVIN

YakPak, Currently I am running a Saito 180 with a Pro Zinger 18 X 6 & hi tec 5945's all around. This engine works very well with the 73" QQ Yak. I started with a Saito 220 ( the one that was on my Goldberg Yak) and ran into engine trouble. At that time I changed it out for the 180 and to my suprise the performance was even better. I believe this being due to less weight / Less wing load...The extra power was not necessary..

Adrenalnjunky, do you intend to 3D this plane or just scale aerobatics? If 3D get the hitec 5985's they are the same as the 5945 just a newer version. They are digital, powerful and fast use 6 volts........Troy built models wants $75+/- opposed to Tower who is getting $90 for them...I think the 645 or the 3305 are fine for scale aerobatics....

YakPak

Emvin,
Thanks for the info.

Regarding the Saito 180.

On the QQ73" Yak, can you hang it on the prop and then accelerate vertically?

Have you tried that on the CG77" Yak with the Saito 180 as well?

Cheers
YakPak

jacklegchris

at 4700 feet, the 180 saito will barely hover at full throttle. I'm looking in to buying a birelli 46cc for my yak. Cost is very good and the weight don't look bad either. May have to relocate rudder servo to back but when I get my pennys together I will give it a try.

EMVIN

YAKPAK, on the QQ 73" it will hover at less than half throttle and climb out nicely. It weighs 11lb 11oz. As far as the Glodberg Yak I was using a Saito 220 and lost the plane to soon to find out how well it would perform 3D. I did read good things about the Saito 220 on the goldberg yak.

YakPak

Jacklegchris,

Your talking about the Saito 180 on your 77" Yak, correct?

Were can I get spec's on the Birelli 46c?

Thanks for your help.

Yakpak

jacklegchris

http://www.scottellingson.com/brillelli_008.htm

here is the web site for the 46cc. Yes I was talking about the Saito 180 on the 77" yak.