What do you think About QQ Aircraft YAK-54 73" with Saito 1.25 installed ? Isn't it going to be enough ? The plane will be lighter with Saito 1.25 and it's not much havier than 69", so I decided that probably should be enough for flying and 3D, I am not power crazy but also don't want leak of power in my aircraft. As I heard 1.80 has problems with ball bearings and is very thirsty, and as I presume with 73" YAk-54 standart 12oz fuel tank I will have only 6-7minutes safe flight time in 3D.
Any opinion is useful.

With the right prop and 30% the 73" MIGHT hover with a 1.25 Saito. But at full throttle. I have a 1.25 in the 69" and it is a perfect combo. You will need a Saito 1.80. When tuned right it will be economical. Dont believe everthing you hear on the web. The bearings are just like every other Saito has. What would make the bearings more prone to go out more on the 1.80? Also every Saito produced will come with a low end needle 1.5 turns rich. Most people dont know that and waste alot of fuel. ZDZ 40F3A will work for the 73" if you want to go gas.
Adam

i tried several engine on my 73" yak and ended up right back where i started, a OS 160 FX. i would think the 125 would be very week on this bird because i tried a YS 140 and was not happy with the power. it did fly it and 3D but not like the 160. just my thoughts. let us know what you do and how it works.

rr

I have to agree with RR, go with a OS 1.60fx. 18x6 Mejzlic prop, and 15% fuel. I ran this combo all last year, with great results. Take off 30 ft. roll inverted and climb out, vertical to you cann't see it. I'm not into hovering, but did do a few, aways up, and had no problem pulling out. Only aa small bit of throttle to hold it up. Os 1.60 ran super, with SlimLine pitts muffler. Just don;t put tank all the way back to wing tube, center between tube and fire wall, and you don't need a pump. We have a Yak 73 in. with a YS1.40 DZ on 30% nitro, and it couldn't keep up with mine. My 2 cents.
Rick

What kind of flight times do you get with the 1.60, and how big is the tank? I want to get the 73" but 10% nitro fuel here is $35/gal, so I've been leaning toward the 69" with a 1.20. Will it be noticeably different?

Thanks.

I have the 73" Yak with OS 1.60. I had the OS 1.20 for the first 6 gallons I got around 9.5 min on a 16 oz tank and land with 1/8 tank reserve. Now with the 1.60 after 1.5 gallon breaking in, I fly 8 1/2 min and have over 1/2 tank remaining because I can use better throttle management with the bigger engine. most flying is at half throttle or less with plenty of power for vertical stuff.

BTW the 1.20 had everything as far forward as possible for balance, but it did balance ok. I made lots of mods when I added the 1.60 and the weight is now 11 lbs. with the 1,20 the weight was 10 lbs.

my feeling is the 1.60 is a better choice all around. I love every thing about this motor. After 1/2 gallon I added the perry pump and moved the tank back to the tube. Still playing with battery position to get perfect CG for my style. Battery is just forward of the rudder servo location, however I moved the rudder servo to just above the right elevator servo with short rod and ball link.
I added Seagull Ultimate Biplane landing gear +3 oz weight over stock but sooo much better in every way.

APC 18 X 6 W = 8450 RPM
Slimline large volume pitts style muffler
Perry pump
Cool Power 10%

This is a great combination but I dont like the APC I think it comes up to RPM to slow, I will play with props in the spring after more break in. Any suggestion???
Hope this helps
Ron

Ron is right on the money. try a xoir 18-6 prop i think you will like it.

rr

Thanks guys.

I have an Xoar 18X6 on the way, Thanks
Ron

My 73" Yak will be delivered Monday. I am down to the YS 140 sport vs. the OS 160 FX. I am inclined to go with the OS 160, but will not install a third party pump/regulator. Does the plane fly better with the fuel on the CG?

Just wondering why you would mount the tank at the CG without a pump on the OS engine - or are you saying you'll must mount tank at firewall?

I only have experience with one plane having the tank moved back to the CG, and it is so much better. Think about the change in balance from a full 12 or 16 oz tank or whatever going from full to empty. I notice a big change between the way my plane flies at take off versus when it's landing. Perry pumps work amazingly well and are only $30.

I really don't want to run a Perry or Cline system. If the plane really flies nicer with fuel on CG then I will get a YS. Otherwise, I have read and heard that the OS 160 with the fuel placed between the firewall and wing tube runs fine off of the muffler pressure.

IMO if I want to get complicated then I will buy YS. Perry systems seem to work great for some, but not for most.

i have used both the YS 140 sport and the OS 160fx and the OS was much stronger and loves 10% nitro. the 73" yak is way better with the fuel tank centered on the c/g. very small changes in c/g drastically changes the attitude of the plane. i have also used the Perry pump on several different models without any problems, just read and follow their instructions. i have heard very good thinks about the cline system but have not tried one yet. just my take on it, good luck with what ever you decide to go with. keep us posted

randy racer

Well the color scheme finally won me over. I was looking to buy the Magic Hand yak in the Orange/Black with CF wing tubes, but they were not available in the US yet. I took advantage of the QQ year end sale and my Yak will be here on Thursday.... OH THE ANTICIPATION IS KILLING ME. I am going to try a RCGF 26cc gas engine on it, won't have the the pull of the nitro, but I am just looking for a good sport flyer.

If you are not looking to hover than the 26 will be plenty of power, (mine would hover but had almost zero pullout). Also the 73" needs as much weight as possible up front to balance.

Im looking at one of these as well. Do they still make the smoked purple scheme?? How will a 26cc perform at 4500 ASL? Im not looking to hover it, but would like some good vertical out of it. I also would like to put a smoke system in one. Altitude seems to be a killer for us up here and we have to use larger power plants. I would like to go gas to get away from the cost of glow fuel and the mess. Thanks for any input.

Tried the YS 140 sport (very nice engine BTW) in an extreme flight yak 74". Not nearly enough power for ANYTHING and really thirsty on very expensive fuel. Went to the OS 160 and Slimline muffler and never looked back. Run it with a Perry pump and put the tank on the CG. Use a 2 oz header tank and you'll never have a hickup or dead stick ! Balance the plane with the header tank full. I use a XOAR 18 x 8 . Found the 18x6 would let the engine wind up a little too much.

You need to spend some time tuning and breaking in. Set the low needle to 1 turn out from where it will fall into the carb case and then adjust the pump and high speed. This engine just keeps getting better and better with a really cool sound.

Open throttle and choke 5 spins (make sure fuel is drawing into the carb first), then flip backwards with a gentle flip and it will start everytime! Your buddies jaws will drop Did I mention that for glow fuel the 10% Omega is CHEAP!

Good Luck - hope you go OS (and they're cheap too!!)

I've come to the conclusion that planes this size need more power than a 26cc has to offer, and am not willing to load the weight of a 40cc on the front of the plane.

From my little bit of pattern experience, I agree that OS two strokes are the way to go - it seems to be the best option for power to weight ratio.

I think for the 73" plane, the OS 160 is the best choice, and a YS 170 would be great if you can afford it (high consumption of 30% nitro).

I have opted for the 69" plane and an OS 120 AX. I have that engine on a 9lb pattern plane and it is pretty darn impressive.

Thanks for the tips guys.

I have to agree with this. It seems the upper limit for the 26cc class motors is 10lb (At least for 3D).

I see ValleyViewRC has a TLT 40cc that seems pretty light. They have tested it on the 25% TLT Yak (Russian Thunder) and said it worked well, so I may try that if the RCGF 26cc doesn't perform better than what I need.

Guy,
How does the 2oz header setup work, I have not heard of doing this please explain. I have a QQ 73" with OS 160 and Perry pump, love it.
Ron

pressure from exhuast or perry pump goes into the main tank pushing fuel into the headertank then the fuel goes from the header to the carb. the header tank always stays full with out air bubles till you are down to the last 2 oz of fuel. this helps stop the lean runs.

rr

Glow goes goes very well, but the 26cc piped w/a smaller gas tank (doesn't need that much fuel) is very comparable to the os 1.60.
I was considering this plane w/a lightened 40cc piped but It may be better served in a 78" ws but price is always a factor as well..

Hey guys I know a guy who put a 45cc rcgf engine on his aw 73" yak and its holding up great and try and get the 160os to do the vertical a 45cc will do! And I have nothing against o.s. they in my opinion are the best glow engines for starting and performance minus there four strokes then its saito but I love my 55ax's but seriously consider the 45cc, and if you did go with it I would put some reinforcing in the fuselage mostly but other than that its a really light engine and a 26cc is more suited for a 68" plane.

Later
Colin

After a lot of reading and some helpful input from Roxie at Central Hobbies here is my setup:

OS 160 FX
Tettra 18 oz bubbeless tank
APC 18x8
Hatori #850 muffler
Hard mount engine

BTW...if I remember correctly someone at QQ wrote that a 35cc plus engine is not recommended and they will not stand behind the product if you try it. Perfectly reasonable on their part and I wouldn't recommend it.