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

Old 03-12-2006, 04:24 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

There are few wrinkles on the bottom of the fuselage that I would like to iron out. I don’t have any experience with foam underneath the thin balsa and Monokote.

My question is, how safe is it to use iron to take care of few wrinkles on this Yak, especially in the areas where the foam is underneath the balsa and monokote?
Old 03-12-2006, 05:19 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Hajduk, glad you see you have patience! I could not wait that long, hence the D/A-50
Old 03-12-2006, 06:29 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

ORIGINAL: 3-D Flyer
Hajduk, glad you see you have patience! I could not wait that long, hence the D/A-50
Well, money is another problem. December for new Futaba 9c, January was five high speed digital servos, February Yak 54, March Smart-Fly system, in April I am very busy at work, and May is BME 55!
Old 03-15-2006, 10:29 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Has anyone else run across this with the GP Yak? The photo is of the control horn sitting on one of the elevators and lined up with the servo arm. Notice the overhang? Seems like there is a lot more room on the one in the manual and in the gallery on the website. I am thinking maybe they used photos of the stab/elevator from the CAP 232.

Anyway, I'm just wondering how much of an angle can the control rods run at from the servo to the horn. Will swivel links help? Sorry if this seems like a silly question but this is my first plane of this size and I want to get it right.
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Old 03-15-2006, 10:30 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Oooops! Sorry. Redundantly redundant there.
Old 03-16-2006, 10:14 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Horn is just sitting there. No screws.
Old 03-16-2006, 12:50 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Horn is just sitting there. No screws.
Correct. That is where it would be attached, lined up with the servo arm. I am a little nervous about putting screws in it like that. Looks like they have increased the cord of the stabilizer, lowered the surface area of the elevator, but left the control linkages/connectors the same.
Old 03-16-2006, 01:04 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Corwin, here are a couple pix of mine. Hope this helps you. Basicly you need to make sure they are located on the wood blocks so the screws have something other than sheeting and foam to bite on. Very important!
As far as them being not in perfect line with your servo arms, get them as close as you can wihout getting too shy on the block area to fasten them. I use ball links on my servo arms this will give you the play if they are off a little bit. Hope this helps....

Got my cowl mounted and a am using the stock D/A muffler...... i had to do a little surgery on the cowl but all in all I like it! I am just waiting for a 22x8 Mejzlik run in prop from D/A and i'll be good to go! I will post a couple "finished pix" as soon as she is 100%.



ORIGINAL: Corwin38

Has anyone else run across this with the GP Yak? The photo is of the control horn sitting on one of the elevators and lined up with the servo arm. Notice the overhang? Seems like there is a lot more room on the one in the manual and in the gallery on the website. I am thinking maybe they used photos of the stab/elevator from the CAP 232.

Anyway, I'm just wondering how much of an angle can the control rods run at from the servo to the horn. Will swivel links help? Sorry if this seems like a silly question but this is my first plane of this size and I want to get it right.
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Old 03-16-2006, 01:32 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

3-D Flyer, that helped a lot! Thanks! You should go to work for Hobbico Tech Support.

Showing off that 14mz case are we? I am going to put my G3 receiver in this Yak. Can't wait! Maybe we can exchange 14mz setups.
Old 03-16-2006, 01:59 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

LOL! No!.......... that was out as i was programing this plane and involved in a thread on the Giants on the MZ........ It was perfect to help hold it still for those pix is all!
Go over to the Giants Forum as we have just started a thread the other day on "14MZ for dummies!" we will be exchanging setups, info etc. It should blow away the Flyers club as it seems to take days to ever get any help thru there! Check it out!

Glad it helped......let me know if you are looking for any more info, I'm glad to help.....


Old 03-17-2006, 08:34 AM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I have purchased a YAK and am wondering what engine would be best a Saito 220 or a Fuji43EI. Which engine has more authority? Thanks for the response I have been out of the hobby for a while.
Old 03-17-2006, 12:25 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I have purchased a YAK and am wondering what engine would be best a Saito 220 or a Fuji43EI. Which engine has more authority? Thanks for the response I have been out of the hobby for a while.
GAJ,
In my opinion the Saito 220 problably have the same power, and maybe better torque than the Fuji. Besides that the powerloading with the Saito may be much better. If you like to go with a gas engine I will consider a ZDZ40RV, an Evolution 45, a 2.4 Brison, or even a 50cc engine. There are some folks going with DA50's, or the new BME 55. Those two might be more dificult to install in the GP Yak, and in my opinion somewhat of an overkill. My personal preference if you don't mind the cost, is the new Evolution 45GX. As far as power to weight ratio the Evolution is on par with the ZDZ, and much better than the Fuji43EI, and the 2.4 Brison. The BME 55 is a really a lightweight engine with plenty of power. However I feel a smaller engine will yield a better wingloading in a 12 to 14 Lb airframe like this one.
Old 03-17-2006, 01:10 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Well Folks..... here's where i'm at..... got it up on the balancer this a.m. With the D/A-50 up front, Ignition, and ignition pack on the engine box.... 1 rudder servo in the tail, and of course the 2 necessary elevator servos in the tail... I am STILL TAIL HEAVY!!! So much that the plane acidently fell off the stand and chipped up the top of my cowl![:@] Fortunately i still have the extra one, so i will have to re-cut and set it up all over again..... What a PITA!!!! OK now that i am finished venting on my stupid mistake, i am finding i am going to have to mount my R/X pack on the engine box as well.... and hopefully she will balance but i believe it will still be tailheavy, I'll keep you posted. So to all setting this bird up Check the best you can your C/G before you set it up the best you can. It's looking like no matter what you do the pull pull in the center of the fuse is the way to go. I was never a fan of pull pull setups but that is just my opinion for what it's worth. I am not going to change it over..... Just some info on those planning to use lightweight plants upfront!
Old 03-17-2006, 01:29 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Well Folks..... here's where i'm at..... got it up on the balancer this a.m. With the D/A-50 up front, Ignition, and ignition pack on the engine box.... 1 rudder servo in the tail, and of course the 2 necessary elevator servos in the tail... I am STILL TAIL HEAVY!!! So much that the plane acidently fell off the stand and chipped up the top of my cowl! Fortunately i still have the extra one, so i will have to re-cut and set it up all over again..... What a PITA!!!! OK now that i am finished venting on my stupid mistake, i am finding i am going to have to mount my R/X pack on the engine box as well.... and hopefully she will balance but i believe it will still be tailheavy, I'll keep you posted. So to all setting this bird up Check the best you can your C/G before you set it up the best you can. It's looking like no matter what you do the pull pull in the center of the fuse is the way to go. I was never a fan of pull pull setups but that is just my opinion for what it's worth. I am not going to change it over..... Just some info on those planning to use lightweight plants upfront!
3-D Flyer

Thank's for the heads up on the CG issue. I was planing on the Pup-Pull setup anyhow, but now I'll make sure to move most of the radio equipment and batteries up front for starters. By the way, how far away from the engine box is the DA mounted? A 1/2" forward on the engine will make a huge difference on the CG. You may try that before cutting into that new cowl. Keep us informed how your final set up turns out.
Old 03-17-2006, 02:56 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

AT, well, it looks as tho she is balancing at 4-5/8" now with 2 1650NIMH packs stacked on top of one another atop of the engine box. That puts her 1/2" behind the recommended 5-1/8" starting point which is permissable in the manual for future flights. The D/A-50 is on the longer 3" standoffs putting the prop hub at the recommended 6-3/4" perfectly. Soooo, looks like she is going to be more of a 15# bird afterall...maybe a hair under. Oh well. The D/A should make this a little more un-noticeable... I was spoiled with the performance of my H-9 Extra 260. I have a D/A-50 in the nose of that is well, overpowered but i like it!
Old 03-17-2006, 03:01 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

So it looks like my stupid idea of putting a Saito 270 twin in this thing is not so stupid after all
Old 03-17-2006, 03:31 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Well it looks like weight up there is going to be your freind from what i'm finding!!
Old 03-17-2006, 08:16 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Would using pull-pull servos for all 3 servos help CG?

I love to see how Great Planes balance this plane with their recommended OS 160 FX.
Old 03-17-2006, 09:35 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

3DFlyer

Do the pull pull, leave the receiver in the center of plane, both batteries up front and she will balance. Remember you want to keep the receiver away from the ignition. Tommorow I will do some more flying so I will report in the afternoon.

I also installed the slimline muffler.
Old 03-17-2006, 10:04 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine


Well, finally my engine arrived from Chief, and I have been able to start working on the Yak. So far installed the ailerons, set up the engine and started working on the cockpit details.

The ailerons I glued with Gorilla glue. I have been using polyurethane glue for gluing Robart type hinges for some time now, so far with great success. Polyurethane expands several times the original volume and creates a super strong mechanical bond. You only need to make sure to protect the hinge point with Vaseline, and protect the Monokote with WD40 or Teflon.

I mounted the engine with a set of 2" standoffs from [link=http://www.forgues-research.com/]Forques Research[/link], and the prop hub is sitting right at the middle of the recommended range of 6 3/4' to 7 1/4" from the engine box. Roger Forques will build you custom length standoffs, with whatever thread size you desire, and they can be anodized in your favorite color too. If it becomes necessary for balance purposes I have a set of 1/4" thick aluminum washers to extend the standoffs.
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Old 03-18-2006, 02:11 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I am still trying to decide on an engine for this plane. I am about to give up on the BME 55 (BTW does anyone have any ratings for this engine besides the 55cc and 2.1 pounds?). I am leaning more towards the Evolution 45GX It has the highest HP of the others I looked at (DA50, Fuji BT43, Zen G-45) and the weight is about midrange at 2.84 pounds. My concern is that the RPM is rated at 25% less than these other engines (1000 - 7500) yet swings the same props (22x8 - 24x10). Anyone have opinions/recommendations on this? I should also mention that this will be my first gasser.

Thanks in advance.
Old 03-18-2006, 02:13 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Almost forgot....does anyone have the RPM ratings on the DA50? I can't seem to find them anywhere and DA's website left that space blank.
Old 03-18-2006, 06:14 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine


ORIGINAL: Hajduk

There are few wrinkles on the bottom of the fuselage that I would like to iron out. I don’t have any experience with foam underneath the thin balsa and Monokote.

My question is, how safe is it to use iron to take care of few wrinkles on this Yak, especially in the areas where the foam is underneath the balsa and monokote?
Hajduk,
I just ran across this and hope it will help you. There is a post in the tips and techniques forum regarding covering/painting foam planes. It was said there is an article in the April 2005 Model Airplane news about covering foam. http://www.rcuniverse.com/forum/fb.asp?m=4010933
Old 03-18-2006, 08:24 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

Thanks Flylow.
Old 03-18-2006, 08:46 PM
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Default RE: Great Planes 25% Yak 81" 12-lb, seen on Fly3D Magazine

I am still trying to decide on an engine for this plane. I am about to give up on the BME 55 (BTW does anyone have any ratings for this engine besides the 55cc and 2.1 pounds?). I am leaning more towards the Evolution 45GX It has the highest HP of the others I looked at (DA50, Fuji BT43, Zen G-45) and the weight is about midrange at 2.84 pounds. My concern is that the RPM is rated at 25% less than these other engines (1000 - 7500) yet swings the same props (22x8 - 24x10). Anyone have opinions/recommendations on this? I should also mention that this will be my first gasser.

Thanks in advance.
Corwin,

Power ratings provided by manufacturers of most gassers can be very misleading. HP ratings are calculated data taking in consideration standard ambient temperature (59 F), and standard air density (Atmospheric Pressure of 29.92 In. Hg.). In most cases the RPM figures are actual (real life) measurements, with SPECIFIC props , i.e. Bolly Clubman, MenzS, APC, Zinger Wood, etc., and they determine how much thrust the same amount of power will produce. In some instances the manufacturers seem to grab these figures out of thin air.

One of the most widely used software to calculate thrust and horsepower output is ThrustHP. This freeware is available at [link=http://freespace.virgin.net/barry.hobson/software/goodies.html]Model Goodies[/link]. In the case of an engine (i.e. MVVS 45GX) turning a 24-10 at 6200 RPM a Zinger wood prop should produce 5.648 HP and 36.08 Lb. of static thrust. The same engine with a MenzS will produce the same power, and 37.19 Lb. of static thrust. In comparison the new ZDZ40 RV-L will need to turn a (much smaller) 20-10 MenzS at 7400 RPM to produce 4.631 HP and 25.54 Lb of thrust. On the other hand a BME 50cc Single spinning a 21-8 MenzS will need to turn at least 8100 RPM !!! to produce 5.906 HP and 37.19 Lb of static thrust.

Keep in consideration that most RPM figures are only achieved under "ideal" engine conditions. Fully broken in engine, with the best gas/oil mix ratio, etc., and manufacturers fudge with this data a lot. In most cases (just to keep you guessing) they don't even give RPM/Propeller figures. If you like download the ThrustHP software and play with the available manufacturer data in order to get a better idea of which engine is better suited for the GP Yak. Specifically look at the WING LOADING tab on the program. There you can enter wingspan, wing chord, and AUW to determine Thrust to Weight Ratios for different engine/prop combinations. In comparing the Evolution 45GX versus the BME 50 I come up with a Thrust to Weight ratio of 2.7:1 for the Evolution, and 2.1:1 for the BME, using the same AUW of 14Lb. That's why I am biased toward installing the Evolution engine on this plane.

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