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

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

Old 11-21-2007, 11:20 AM
  #776  
Walt and Sage
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine



Mine came out VERY noise heavy with recomened CG...
I would sugest that you lift the plane with the wings on at
the wing tube and then go from there...

Old 11-22-2007, 12:41 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Check my build page 2 for pics of my DL-50 install.

I have since installed a Futaba 3004 on the choke. I installed the included extra servo mount right next to the throttle's 3010. Basically the same nyrod setup as throttle. Didn't extend the choke's arm (like I did on the throttle). Bigger hole in firewall for the choke's ball link to fit through without rubbing. Choke's nyrod forward-most brace connection point in the hole through the gas tank former.

Also installed a EMS/Jomar kill switch on ignition and replaced my solder control rods (elevators and ailerons) with a 4-40 threaded rod/carbon-fiber combo.

I'll try to get more pictures online soon. Mine should be ready to maiden as soon as I get the surface gaps sealed and do some more tweaking on the dual-rate programming.

The last time I did a pre-balance, mine was tail heavy. Now that it's finished, I need to balance it for real and see how much nose weight I need to add to hit the recommended "forward edge of the wing tube" CG.

ORIGINAL: pooks31

Great thread

Does anyone have any photos of their DL-50 installation (especially the throttle and choke linkages) in the Yak? Also, any advice from you DL-50 guys about CG balancing? i.e Pull pull vs servos in the tail; and engine standoff lengths? Thank in advance
Old 11-22-2007, 01:02 AM
  #778  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I have a Brillelli 46 and have the rudder servos in the tail, like the instructions recommend- CG is fine there for flying but is a bit aft of recommended. I had the servos in the forward pull-pull configuration and it was a bit too nose heavy for 3D flying.
Old 11-25-2007, 07:02 AM
  #779  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Thanks guys

Vince you rock! That build thread on your website is just great - thanks mate. I dont start my build on the Yak for another 2 weeks because I'm moving into a new "workshop". Whoops sorry I meant new house (wife looking over my shoulder while typing). So my apologies in advance for the gasser newbie questions I'll be asking.

Cheers
Old 12-04-2007, 05:07 PM
  #780  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Can some one measure how much is cowl diameter to me please? I thinkwhat height engine fits in.
Old 12-04-2007, 10:33 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

See post #752.
Old 12-05-2007, 09:49 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Choopi,

Have you flown yours yet?
Old 12-05-2007, 10:38 PM
  #783  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Ya,

I flew mine 2 or 3 times, but now with winter it's not fun[&:]. I like it but it's not perfect yet, I will have to midify the landing gear, I don't have enough clearance, I broke a prop 25$[&o] Not a bad plane but as right now I need to fly it more to see if I realy like it or not. Some plane just fit right from the first day, but there is not to many of those.

What about you?

The DL 50 is a good match for it.
Old 12-05-2007, 10:40 PM
  #784  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Mine is finished except for final balance. I knew it was tail heavy and it's even worse now that it's finished. I'm balancing upside-down as directed in the manual.

To put the CG at recommended 5-1/8" (almost to the leading edge of wing tube) I'm going to have to add 16 oz. to the firewall.

Or, should I try to only hit 5-5/8" (middle of wing tube). Looks like that will only take 10 ounces.

First flights will be on recommended low rates and I need it to fly real easy till I get used to a large plane like this.

My build pages should show what's in the plane and where. My battery and receiver is on the forward RX tray (just behind the wing tube).
Old 12-05-2007, 11:40 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Hey guy's,
Just wanted to give you an update. Have had only about 6 flights so far mostly due to prop clearence issues. I have finally resolved that problem by replacing the stock gear with carbon fiber gear from Graphtec and placing it from underneath the fuse this has given me much more clearence!
I found that it flys heavy, this plane is over 15lb and does not have enough wing area for good 3D, more for IMAC, sport and precision flying.
I would change my DL50 to an OS 1.60 for weight saving but i know it wouldn't have enough power.

I have just recieved my Extreme Flight Yak 54 88" it's a huge plane designed for a 50cc has over 1400sq.in wing area and looks more like 30%
I have 2 friends who fly them and there is no comparison. Check them out!
Old 12-06-2007, 02:20 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Med,

If you get a chance ...

The Graphtec part number (or new dimensions of the longer gear) and a picture of your fuse mod would be helpful.


ORIGINAL: med601

Have had only about 6 flights so far mostly due to prop clearence issues. I have finally resolved that problem by replacing the stock gear with carbon fiber gear from Graphtec and placing it from underneath the fuse this has given me much more clearence!
Old 12-06-2007, 07:59 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Same here, I had to add weight to balance it. I would have to agree that the EF Yak 88 is a better plane for 3D. At the end if you add money for an other landing gear that plane is not a deal anymore.

Eric
Old 12-06-2007, 10:09 PM
  #788  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Here are a few photo's of the mod. There really is no need to upgrade to the carbon gear, it's only an inch taller but by placing it from underneath the fuse you gain much more clearence. I have a 23x8 and have 5" clearence
Old 12-06-2007, 10:26 PM
  #789  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

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Old 12-06-2007, 10:41 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I have been flying my Yak with the DL in it now for a few weeks. It flies pretty good, but nowhere near as good as the GP Cap with the DL in it. It rolls alot cleaner, and flies smoother, but for all out 3D the Cap kills it. I was pretty frustrated when the gear yanked out on a perfect tail first landing at a snails pace. I have it on video and sent it to GP and told them I didn't feel this was acceptable. I started with the cg about 3/4' behind the recommended and it seems about perfect, but to even get the cg there I had to put the motor out another 1/2" and mount all the batteries up front. I have 3 GP planes all with DL motors on them, and so far I am least impressed with the Yak. I am hoping that as I fly it and get it dialed in more that I will start to enjoy it more. Mean while, the 35% Yak keeps the smiles coming for me
Old 12-11-2007, 04:08 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Yes, the EF Yak 88 looks like a cool plane but isn't it a different class? While we are oversizing the engine (by putting 50s in the GP-Yak) the EF Yak 88 appears to be a dedicated 50cc airframe.

It's still $200 more than a $400 GP Yak and a $50 extra pair of gear.

A friend just bought a Lanier Yak54 - 87" while they were just on sale at Tower for $420. I guess he got one of the last one because now they say Discontinued.

Maybe I will get to maiden mine while the weather is still nice here. They other day it was 81. Usually it's in the 70s during the day.


ORIGINAL: choopi

Same here, I had to add weight to balance it. I would have to agree that the EF Yak 88 is a better plane for 3D. At the end if you add money for an other landing gear that plane is not a deal anymore.

Eric
Old 12-11-2007, 04:14 PM
  #792  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I thought all the main radio gear (and it's batteries) had to stay 10-12" away from the ignition. That works out to be the forward radio tray behind the wing tube.

I don't know ... just asking.


ORIGINAL: mtwister

... and mount all the batteries up front. I
Old 01-09-2008, 06:54 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

bump
Old 01-10-2008, 09:33 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I got a chance to fly a friends GP 80" Yak several times, he has OS 1.60 APC18X6W, CG @ 5 1/4". Dont know the weight but I liked it, had enough power to go vertical straight up out of sight, coupling in KE was acceptable, rudder authority was great, KE figure 8's with little rudder. Aileron authority is powerful, the elevator was a bit sensitive, we dialed in some expo & rates to smooth it out. Inverted flight was just about perfect at 5 1/4", it almost maintained level flight, just dropped slightly, I think he added 4-5 oz. near the firewall.
Landing was super easy, the thing just floats on in a little nose high but no big deal, my friend kept on bouncing it because he was pumping elevator too much. I told him it almost lands itself in a three pointer, dont need much elevstor or flair at all. Very cool!!!
I hope he lets me fly it after break-in, I want to check out hovers,TR, by the way, harriers were good too, very little wing rock, easy to control with a little aileron.
Old 01-20-2008, 08:44 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Ok, read this entire thread and decided to build one. Found it for $300 at local shop who couldn't get rid of it so I took the plunge. From reading this thread, my entire goal for the project was to keep it as light as possible while using a gasoline setup and get the CG correct without adding any weight. It turned out better than I ever expected.

Specs as follows:

Fuji Imvac 43 EI-2
4 - Hitec 5625's on Elevator/Aileron
Single Hitec 5955TG on Rudder
JR ScanSelect Feather PCM 790 Receiver
Castle Creations 10 AMP Switching BEC set at 5.4 volts for Fuji ignition from A123 lead (new, weighs 11 grams!)
Single A123 2300 for EVERYTHING (4 leads from battery--2 to redundant switches for receiver, 1 to ignition from CC BEC, 1 balance lead to charge)
PT Carbon Prop 21 x 8
TBM Carbon Spinner
Graphtec Carbon Landing Gear and Tailwheel
PBG Carbon Wing Tube (30mm x 690mm)

To help with the CG, I used a single pull/pull 5955TG for the rudder mounted in the forward position of the stock tray. The A123 battery was mounted in the bay in front of the gas tank. I mounted the throttle servo in the engine bay and put a magnetic choke on the servo lead (to minimize interference).

The good news! All up weight, using stock spinner, gear, wingtube and tailwheel before mounting the carbon goodies is:

13.4 lbs weighed on a digital scale with +/- 0.1 lb accuracy!!!! Weighed it a dozen times to make sure I wasn't skewing the reading while balancing it on the scale. The CG is at the front of the recommended starting point. I know it's conservative from GP, and I can move the battery back next to/behind the tank to adjust.

I fully expect it to be 12 lbs, 14 ounces when I put on the carbon spinner, wingtube, and tailwheel as i will save 6 -8 ounces. I'll keep you posted.
Old 01-20-2008, 10:20 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Good deal!

Now it's time to fly that baby! C of G is not easy to get with that plane. Let's see some pics do you have any?

Eric
Old 01-20-2008, 01:39 PM
  #797  
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Just finishing the decals. I'm making some custom graphics for it. I will post pics soon.

Brian
Old 01-25-2008, 10:09 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

That's incredibly light given that motor's not the featherweight of the crowd. What's the top-end of the scale's range?

Mine needs to go on a diet (like me!) at 15lbs. 4 oz. With 5 JR 8611s, Brillelli 46 with a 1500mAh single-cell, and Duralight 2600 flight pack and regulator.

I've been meaning to go with carbon gear and wing tube. Can you weigh your gear and tube and post the results here? Also, where did you get them? Thanks.


Al
Old 01-25-2008, 02:19 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

What kind of battery is the A123, Lion? 2300 doesnt sound like much if its running the ignition & reciever/servos?
Old 01-26-2008, 12:28 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Do a google search or click on the underlined A123 text in the post. Thanks to your question, I finally took the time to look into it in some detail and they seem like very promising technology with some trades as compared to Li-Po based chemistries. Summarizing:

High discharge rate (50C+)
Lower voltage per cell (3.3 vs. 3.6)
Slightly heavier
VERY fast charge elapsed time. 90% charge in 15 minutes or less (very nice!).
Physically slightly larger.
Much longer cycle life.
Low impedance growth over life.
Capacity not affected significantly by discarge rate (abuse tolerance).
Less expensive(?). Used in new-gen cordless tools (economy of scale?) so it must be goo enough to keep the liability lawyers happy.

Looks like something I'm gonna keep an eye on. Overall seems like a good balance. Time will tell.

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