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Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Old 09-30-2006, 12:58 PM
  #501  
Hajduk
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Kroma 50i weighs 1575g (3.47 lbs). I used ¾” stand offs to install it. And I removed ALL three servos (two elevator and one rudder) from the tail section and only then my Yak 54 balanced at 5 1/8! This is with stock Great Planes (GP) spinner and Bolly 21X8 Wood propeller installed.

What am I doing wrong? Does anybody know how to contact Great Planes tech support? I did not find any phone numbers on GP web site.
Old 09-30-2006, 05:19 PM
  #502  
xtdsm
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

ORIGINAL: Hajduk

Kroma 50i weighs 1575g (3.47 lbs). I used ¾” stand offs to install it. And I removed ALL three servos (two elevator and one rudder) from the tail section and only then my Yak 54 balanced at 5 1/8! This is with stock Great Planes (GP) spinner and Bolly 21X8 Wood propeller installed.

What am I doing wrong? Does anybody know how to contact Great Planes tech support? I did not find any phone numbers on GP web site.


what you need to do is get some longer stand offs (~3" ) and use pull-pull on your ruddar (you can keep your elevatores servoes at the back) and go from there. make sure you go over your engine box with epoxy tho.

good luck
Old 10-01-2006, 08:50 PM
  #503  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Maiden Flight Today!

The Yak flew great. Wind was about 10 - 15 knots and the plane did not hardly notice. Loops and rolls very clean - no 3D until get a little more time on the engine and I feel it out a little more, but lots of power for sport flying. NO WAY WAS IT TAIL HEAVY [8D]. The plane slowed down nice and landed nice in an unsteady wind, no cross wind. Dead stick landing on second flight - engine died just as I turned toward runway into the wind - easy landing but things were in my favor.

This is my first Giant Scale and my first gas engine. Setup is: Brillelli 46 engine with EI and 22x8 Xoar prop, Hitec 645 all around except throttle, JR PCM receiver, 5 cell 2300 mah nimh control power, 4 cell 2300 nimh ignition power, extra 8 oz weight in the nose box. Flew it without the cowl and spinner.

Problems:
1. Pull -pull rudder cables were not tight enough causing the plane to jump around a little - easy fix.

2. Engine: I hooked up the engine wrong - gas going into the air balance instead of the fuel inlet and I uhhm pressurized the fuel tank from the engine exhaust nipple. OK it wouldn't start like that. This is where flying in a club pays off and together we fixed it all. Also had to reduce the low idle setting to get it to idle lower.

3. Sullivan tail wheel spring bent and pulled out of the rudder. This made for an interesting taxi after the first flight. Problem fixed but I really need a better tail wheel setup.

4. Engine died on second flight I think due to stiff inner tank line. Had 1/4 tank and I do not think the clunker brought the line over and I gulped some air. The gas tank is tall so when it goes over ( I was pulling hard turns) the tank level goes down. Heavier cllunker was recommended by a fellow club member - so I will try it. I think earlier in the post someone recommended car gas tank lines from an auto parts store for a more flexible tubing.

Despite the problems it was a very good day at the field !
Old 10-02-2006, 04:48 AM
  #504  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Glad to hear that the maiden was ok. Just interested to hear where You ended up with the CG and also the final weight on Your Yak.

Nol
Old 10-03-2006, 08:07 PM
  #505  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Okay Im back. I was flying the QQ yak for the summer. I am rebuilding the GP yak today. I decided to go with the os BGX I had lying around. Should prove to be a good combo. 20x10 prop and pitts muffler. Only draw back, 12.00 a gal for the fuel. I installed evrything today, except the muffler, (no UPS today), I did put 7.1 0z on the engine to simulate it. I balanced out at 5.5". All servos in the tail. Battery against the engine box. Cant wait to fly it...

Dave G..
Old 10-11-2006, 12:26 PM
  #506  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I am trying to decide between this plane and the giant super sportster. How would a Brillelli 40gt fly this thing around? My other question is I have a futaba 7c radio, and there are 2 servos for the elevators, I can use a servo reverser on them. But what about the two servos for the rudder? Would I need another servo reverser or would a Y cable work for that?

Thanks
Old 10-11-2006, 12:58 PM
  #507  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I am using a 7C in mine.....I put the rudder servos on a Y-connector and the elevators on a servo reverser. Works fine.
Old 10-11-2006, 03:25 PM
  #508  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Will the Brillelli 40GT get it done?
Old 10-11-2006, 03:34 PM
  #509  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I would think so. Mine has the 43cc Fuji. The 40 might not give ballistic perfomance but it would surely be enough for limited 3D and IMAC type flying.

Be sure to read a few posts back about the CG problems we have had. Put everything as far forward as you can without risking radio interference from the gas engine.

Great Planes has an awesome product, but don't build it by their recommendations for the gas engine. Put the rudder servos in the fuse using the pull-pull setup.
Old 10-11-2006, 04:47 PM
  #510  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Chris,
No sweat on the rudder servos. When you use the install for a glow engine they are mechanically ganged together, (so they turn in the same direction) and when you do the gas engine install the servos are mounted with the servo arms both pointing down. Because of that they will turn opposite of each other, and that's what we want on the rudder (one arm pushing while the other one is pulling)

See pages 15 through 18 of the [link=http://www.greatplanes.com/manuals/gpma1411-manual-v1_1.pdf]Great Planes Yak 54 Instruction Manual[/link] and you can see both install methods. Let me advise you that so far as my own experience if your engine weights less than the Fuji Great Planes 43 EI I recommend you will end up adding weigh in the nose. And the 3.5lb (1588g) approximate weight, with muffler Great Planes advertises is way too conservative. If you add the optional canopy floor, and add a pilot (behind the CG) you will still end up being tail heavy. In my case I used a Evolution 45 GT with a Bisson Inverted muffler which weigts 4 Lbs. versus a Brillelli 46 which weights 7.1 ounces less!!! than the Evolution engine. with a Bisson muffler

If you plan to use a gas engine ideally you want to install a single 170 oz. torque servo with Pull-Pull, have all your batteries all the way in the engine box, and don’t add a pilot figure in order to avoid adding weight in the nose . See [link=http://www.rcaerobats.net/GAS_ENGINE_WTS.htm]Bob Pastorello's RC Aerobatic Page[/link] for some realistic engine weights measurements.
Old 10-11-2006, 05:02 PM
  #511  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Thanks for the advice!!
Old 10-11-2006, 06:53 PM
  #512  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

How does that Fuji 43 pull the yak around? After doing some research I might go with that engine if its powerful enough.

Thanks
Old 10-14-2006, 09:28 AM
  #513  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

so is this thing gonna get down and 3d or not?
Old 10-14-2006, 12:46 PM
  #514  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Can someone tell me how the plane is from the ground to the top of the cowling, I want to know if I am going to have to take the gear off to get it in the trunk of my car.

Thanks
Old 10-14-2006, 03:33 PM
  #515  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Don't plan on taking the gear off....it is 2-piece gear mounted with the screws in the fuselage...under the fuel tank. If it is too tall then don't get the plane. I will be too mauch of a pain in the butt.

About 18.5" at the cowl and 19" at the tail.
Old 10-15-2006, 04:15 PM
  #516  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

what are ther servo arms types/ and lengths you guys are running on the ailerons and elevators

thanks
Old 10-15-2006, 05:12 PM
  #517  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

ifi2,

My experience so far has been with a UCD46 and an OMP profile Edge - so this is a big step up for me, not only in the plane size but to gas engines as well.

Took her up today and she hovered fine but it was waaay up there because I am not familiar with the stall tendencies. Falling forward out of the hover and a forced stall was a piece of cake - it didn't really even appear to stall much. It liked to torque roll a lot more than my UCD in a hover and took a bit more right aileron to keep it steady. But overall it was very steady. The Brillelli seemed to handle it fine.

My main focus is on the engine - Brillelli 46 and getting it tuned right - today was my 3rd dead stick out of 5 flights but I think I now know why thanks to a fellow pilot at the field. I am using a standard servo on the throttle and it is not repeatable within enough tolerance to hold a low idle at min throttle. I have bought a digital today to correct the problem. I also think I have the engine a little overproped at 22x8 and will put a 21x8 on it though I may go with a 21 x 10 later - just have to experiment nd see what works best.

One thing to note is that this plane floats in like a glider - even dead stick. My second deadstick I overshot the field and we have a huge landing strip.
Old 11-04-2006, 06:42 PM
  #518  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Hey all I finally got mine in the air today after 3 long months of slowly getting everything I needed. I have the DA 50 in it and man it's a beast. My first gas engine. I didn't have to touch the high or low needle settings because DA sets and runs all there engines here at the factory. Since I live in Tucson which is were DA is located they told me not to touch it until I have ran 2 to 4 gallons through it. Then Brian at DA said he will come out to the field and tune the engine for me. Sure is nice living right down the street from Desert Aircraft. Anyhow the engine started right up it's running a little rich but has plenty of power. My plane weighs 15 1/2 pounds and I can go verticle with less than 1/2 throttle. I can't wait till this engine breaks in. My first landing was a piece of cake. You got to love this plane.
Old 11-06-2006, 04:49 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Did you use the spinner that came with the plane for your DA-50?
Old 11-13-2006, 04:32 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

After reading this entire thread, I'm ready to start building my GP Yak 54. I still haven't made a final decision on the engine or servos, so your input will be appreciated.

While the OS 1.60 FX is a nice fit, if sticking to glow, maybe the OS BGX-1 3500 (with Bisson Pitts muffler) would work also work nicely (and have a little more power to spare). If making the jump to building my first gasser ... I suppose the 4.2hp (GP recommended) Fuji Imvac BT-43EI-2 would be my choice. However, I'm not really sure of all the Pros and Cons of gasoline (aircraft complexity, support equipment, dependability, etc).

I read about the balancing problems, so it sounds like the rudder servos will go inside (on pull-pull) no matter which engine I go with. I've been running all Futaba gear (FM at 4.8v) lately. For the 6 servos for the ailerons, elevators, and (2 on) rudder I was thinking about Futaba s3305 MG (99 oz-in at 4.8v) for $35 ea. However, I was just looking at the Tower site and it says the s3305 is "not for airplanes" . Maybe someone knows what's up with that?

I would be willing to go the next step up on the servos for a little insurance. But, for Futaba Metal Gear servos, the price doubles as you jump to MG Coreless analog servos, and MG Digitals are almost triple. In no way do I want to cheap-out on servos (the posts about stripped out and failed servos are pretty scary) but before I spend $500 just on servos I wanted to ask someone first .

Old 11-13-2006, 04:54 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Since you posted this, a couple of others have also reported hinge failures. Did you end up building yours with real Robart hinges after all?

ORIGINAL: DOC

I just started to assemble my Yak today! I noticed the Robart hinge point (knock offs ) are of poorer quality than the real thing. The pin has a smaller head , and the peened end, isn't very well peened. I tryed to repair the questionable pins (rivets), but they get too tight and don't work well.
Has enyone had any pin failures? Or is this a non problem.........?
I think I'll use the real thing just in case.
Thanks, DOC
Old 11-16-2006, 09:03 AM
  #522  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine


Tesla1856,

I use 3305's and never had a problem on either of my GP Super Stearman or Yak. The manual also shows 3305's. I can't see the extra cost for .05+ sec. response for the type flying I do. I'm also using a single 3306 pull-pull for the rudder over 300+ oz. of torque @ 6v.
I mostly buy from [link]http://www.wholesaletrains.com/Airplanes2.asp?Scale=None&Item=giantarf[/link] 3305 are 32.00 ea. and the GP Yak 54 was 349.00 and always free ship. But you need to purchase a plane or two to be eligible for club rates (get a buddy to share cost).

The supplied point hinges are fine. Just oil the hinge before epoxy. Also forget the tail wheel, upgrade it to a Sullivan type. I use the 120 U-Can-Do replacement for about 7.00. I did have to add 10 oz. lead to get the cg right with a Brillelli 46 but will remove half cause she flys a little nose heavy.

glowguy
Old 11-16-2006, 01:13 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

ORIGINAL: glowguy

Tesla1856,
I use 3305's and never had a problem on either of my GP Super Stearman or Yak. The manual also shows 3305's. I can't see the extra cost for .05+ sec. response for the type flying I do. I'm also using a single 3306 pull-pull for the rudder over 300+ oz. of torque @ 6v.
Thanks for verifying that. Yes, it's weird that Futaba/Tower don't rate that servo for airplanes (especially since the manual shows them in the pictures). You and others are using them in the Yak, and although it's a smaller plane, myself and others use them alot in the Seagull Edge 540 (60-90 size). Like you said, as I compare the specs., the only thing I see is that they are a little on the slow side ... but it's only hundreths of a second.

I mostly buy from [link]http://www.wholesaletrains.com/Airplanes2.asp?Scale=None&Item=giantarf[/link] 3305 are 32.00 ea. and the GP Yak 54 was 349.00 and always free ship. But you need to purchase a plane or two to be eligible for club rates (get a buddy to share cost).
Excellent prices ... thanks for the tip. That might be cheaper than Tower Club prices even playing the rebate/coupon code game.

The supplied point hinges are fine. Just oil the hinge before epoxy. Also forget the tail wheel, upgrade it to a Sullivan type. I use the 120 U-Can-Do replacement for about 7.00. I did have to add 10 oz. lead to get the cg right with a Brillelli 46 but will remove half cause she flys a little nose heavy.

glowguy
I took a supplied hinge down the Rebel yesterday, and compared them to real Robart hinges ... we couldn't tell a difference.

So, one of these:

[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJUN6&P=Z]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJUN6&P=Z[/link]

[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFV48&P=]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFV48&P=[/link]

Old 11-16-2006, 09:14 PM
  #524  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Hello, I know there is a market place. But for any one needing an upgrade for the landing gear I have a used pair of custom TNT ALU. gear. They are bullet proof. They were built 1 1/2" longer for better prop clearance. (DA 50) Cost $90 will sell for $45. The new owner will love these with out a doubt. Have other parts as well.
Old 11-16-2006, 11:56 PM
  #525  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

As far as the hinges go just make sure they are aligned as good as possible otherwise I think they will bind and eventually fail. I may have installed one a little off - I can hear it groan every now & then.

As far as the CG goes I have a Brillelli 46 and no weight in the nose and have no CG problems at all. The rudder servos are in fuse but I may put them back in the tail. I think GP has an extremely conservative CG set for this plane.

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