SJN

Hi guys

I just ordered one of these for my Saito 84FG R3

Since these have been on the market for some time now, someone must have bought one already
Any tips, tricks, or general info on it ?
And how about CG ?


Since the saito 84cc might not be the most powerfull engine out there for this size plane, I will try and build it as light weight as possible.
Making the tail as light as possible, and move all the servos up front ahead of the CG, to keep as little nose weight as possible.


Few pics I found on the net of it.....

IFLYRC-RCU

My Feedback: (28)

Nice looking aircraft! I have some experience with this mfg...

Things I would check - make sure all the formers are glued in properly. Take a good look at ALL glue joints and formers installed to the fuse. Check the firewall - make sure it is fully attached....

Caution on the canopy - they tend to be a bit brittle - warm them in hot water before trimming them to size. Their retracts are sloppy generally... I found the Robart 635s are the same size, but work reliably.

Google You Tube - bet they have a flight video out there. Their planes generally fly well.. just need some attention to detail.

Have fun !

SJN

Thanks.

Yea, I have their spitfire and Bearcat, and they are a little rough out of the box. :-)

SJN

Yak showed up today, and it lioks very nice.

I also have the spitfire and bearcat, and this one is much better quality overall.
Lots of improved bits on it.....its actualy usable out of the box without too many custom mods


Only thing I have to change so far is the stab incidance.
The front tail spar tube needs to be cut free and re-glued to align both stabs.....not a big job.

I like the paint job, allthough the bottom of the plane should have been light blue instead of gray......but ill survive for now.

I hope the saito 84 will be able to haul it into the air.
The plane is bretty big, and will have to be built light.

kimhey

I bought the la-7 from the same manufacturer, modified it and installed a Moki radikal 150ccm. Your Yak is pretty much the same model, and you will probably be ok power vise, if you build it light enough. Speed will most likely be "moderate". My model ended at 21kg, with a lot of modifications/reinforcement.

I can post photo/video if you want.

Kim

SJN

Hi kim.

Yes, please post some pictures.

I have the bearcat with the moki 180, at around 18kg This yak will have to be way lighter. Have not flown the bearcat yet.

kimhey

Photos on my home computer, so I will post them later, but here is the video of it flying. I went for an unusual paint scheme.

https://m.youtube.com/watch?v=qUFc-r1eyxY

SJN

Great video...flys great :-)

Did the CG in tha manual work out for you, or have you moved it ?

kimhey

The cg in the manual works great. I did xcheck with the building plans for the David Anderson 1:4 la-7, and the cg is practically identical.

SJN

Thanks for the info Kim :-)

Im getting the engine installed so I can get an idea about the CG.

With the engine and batteries on the engine mount box, the fuselage is exaxtly on the CG as it is without the wings on, and no servos in the tail and no tail wheel.......
So it will probably be tail heavy, and need soe weight in the nose.

I have calulated that I need about 500g in the nose to compensate if I install the elevator serovs in the tail as described in the manual.

The servos in the wings are behind the CG, bu the landing gear infront, so maybe they will cancel out each other.

This plane is quite neat as you can easyly remove the tail unbolting 4 bolts.....it will fit even the smallest cars if you have transportation problems.
I have a big car, but it is a pain to get a large fuselage out and down the stairs of my small apartment, so I might just seperate the fuse.......but.....
I had plans to move the elevator servos up front near the CG and using long carbon pushrods to the elevators.....but I cant do that if I want the tail to be removable
Will have to install everything but the elevator and rudder servos, and see how the CH turns out.

Have to build this one light......

SJN

This particular Yak has a PW 1830 radial, and has a single large exhaust outlet in the bottom of the fuselage.
This is great, as I will use this as an extra engine cooling exit.

Since the 3 saito flex pipes can not reach, im going to get a large diamter 90 degree pipe, and direct the exhaust into that, and out of the plane like on the fullsize.
Hope this will work out ok, as I have not tried this before.

SJN

little more progress on my tailpipe

Got it cut to length, and installed at the front.
Will be boxed off inside the fuselage so the engine cooling air wil go out of the fuselage, and the aft pipe mount will be in there too.
Will make a bracket for the 3 saito flex pipes too so they do not vibrate and crack......hopefully :-)

Looking forward to hearing the exhaust not to see if the steel tail pipe has an effect on the sound it makes.......hope the large diameter amplifies the sound.....we will see

kimhey

Hi Sonnich, good progress!
I am posting some of my photos for your inspiration (even if it looks like you don't need it..). The position of the l/g on the CyModels La-7 was nothing near scale, so I moved them (have not checked the Yak 3u). A bit of extra work, but worth it in my opinion.
I also ripped off the plastic covering and glassed the wings and tail. One of the pictures is showing the model in gray primer, and that was how it looked when I maidened it. Now it is dark gray metalic, and looks badass in the air
The cockpit is not russian....I fitted a P-47 1:4 cockpit I had laying around. The engine mount looked too fragile to handle my Moki, so I glassed it with 3 layers. Now it is rock solid!
I did have some heat issues at first, so the cowling had to be opened up some, unfortunately. The holes are covered with metal mesh.
Kim

SJN

Thanks for the pictures :-)

Im going to lay glas on my engine mount too, to give it some extra strenght, and to close up the holes.
My carb will then only draw cold undisturbed static air from inside the fuselage....thats the theory anyway :-)

I would love to make heaps of alterations to this plane to make it more scale......but It will take too lang, and just be another unfinished projekt. :-)
My goal is just to get my saito engine flying as quick as possible.

CG is just the largest issue when using a "small" engine.
The tail is long, and the nose very short, but it looks great :-)

SJN

little more progress.....not much time to build after working all day

Got the engine mount glassed and painted.
final install of my exhaust tail pipe, and the saito flex tubes.

Still need to install 2 guide tubes for the low and high needle adjustment. fasten the ignition, and make mounts for my 2 big Nimh RX batts.
Then I can move on the the rest of the plane.

Will be installing the 2 elevator and 1 rudder servo right at the fuselage joint so I can remove the whole tail for easy transport.

Checked the CG, and with the gear on the wings with te servos, CG seems to be very close to CG.

Weighed the plane without the gear, tank, plumbing, servo hardware and and it is 12.5kg/27.5 lbs

I think fully fuled it will weigh about 15kg, /33lbs or a little less.

Sounds a bit heavy, but it is realy light for the size of this massive plane.
Check out my fat arm in the pictures....I have pretty big hands.....they look small on the wing :-)


Found some videos of a aVailly Aviation Fw-190 nd saito 84 that weighs 17.5kg /38lbs , and it seems to fly scale.....not overpowered
https://www.youtube.com/watch?v=YtRI0P2mTS8

dgiatr

Hi, SJN !
great work you are doing there!.
A friend of mine had the same plane and i think he had a 90 cc 2 stroke gas engine on it.
plane weight was at about 20 kgr!....(ok he made some serious reinforcements probably everywhere!)
you have to built it really light for that engine you will use!
I will advise you to be carefull in case the engine will stop running...you will have to put the nose down for emergency landing really fast!!!
Plane flies fantastic when the tail gets some good amount of air flow but when that stops .....that plane becomes a real beach!!
you have a narrow tip which makes that plane prone to tip stalling...thats how my frind crashed his plane....engine stopped but he didnt put the nose down to get some airspeed instantly and at the next second plane was in a "nice" spin....( ok it was a heavy plane thought)
The same thing happened to me with my ESM LA-7 ...its a wonderfull plane to fly as soon as you have some airflow but when you dont......

SJN

Thanks for the tips :-)

wow...20kg...that is a bit more than mine will weigh :-)
I think the lighter wing loading on mine, and I have chosen a little more forward CG will make sure it will not tip stall too easy I hope.
There are some good videos out there that show how nice it realy flys.
The tail is quite small compared to the rest of the plane....but it is scale....will just have to live with that :-)

We will see how it goes :-)

kimhey

20 kg is no problem, 15 kg is silly light but achivable if you do it right. Mine is 20+kg and it still does not feel heavy in the air

SJN

Got a little more done.

Installed 2 carbon low/high needle guide tubes for the long screwdriver that is included with the engine .
installed a neat tachometer on te firewall from Hobbyking that will show the RPM with the cowl off.
Just double side taped it on. Might move it into the fuselage when the engine i finaly broken in.
Tidied up the wiring, and installed my 2 x 4,8V nimh RX batteries. One on each side of the engine box.

So now I just need to install the throttle linkage, tank, and do the baffling inside the cowl, and that should sort out the front end of the Yak

SJN

Got the tail almost finished.

Decided to glue the stabs onto the fuselage, and move the servos to the front of the tail section to get the weight up front.
Had to remove the front tail spar to align it properly, as the factory did not do a good job on that.

I used the stock rudder servo mount, but had to make my own one for the elevator servos, as they are not mounted in the stablizers.
Used carbon rods supported in sulivan outer pushrods so they dont grind up against the fusealge. Nice solid setup.
Had to move the elevator control horns further inboard, so I just covered the mounting holes that were done at the factory.

Got the tailwheel installed, but the spring steering system seems pretty weak, so I think ill just install normal cables instead for direct steering.


Just needs a bit of paint and it will all be good

kimhey

Nice

SJN

Thanks Kim. :-)

I have to build it nice, otherwise it wont pass the airworthiness inspection we have for models over 7kg.

SJN

Man....I hate the stock tailwheel setup.....it looks so ugly.

I have a retract from hobbyking that would work fine, but I will have to add weight in the nose to offset te extra weight gain in the tail.......and I dont want that.....bummer


Manual says to use springs to connect the tail wheel horn to the rudder closed loop cables, but I can not get thet sorted out to work properly.
So I will be useing left overs from the closed loop cables and linkn them to the fiberglass rudder horn instead, for a more solid setup.


I have assembled the plane again, and it is about 1-2cm tail heavy as it is right now......so It will need some dead weight in the cowl.

kimhey

The stock tail wheel is awful scale vise, but I installed it anyway. I flew 3-4 flights before I removed it, and installed a retractable tail wheel and gear doors. I would leave it on, and modify later if you find it "nesseccary" to do so
It might work just fine to leave the steering out as well, I have tail wheel steering on my Cymodels La-7, but not on my C-arf Spitfire....and that works ok too.

Kim

SJN

Yea, I will leave it as it is for now.
Will see how the CG turns out after the first flights, and how good the vertical is, and see if I want to add more weight

Moving on to the wings.
I was going to re-inforce the wheel wells, but they area actualy very well constructed and glued together on this model.
So I will leave them as they are....just add a little extra glue here and there

I leak checked the retracts under water at 100psi/7bar for leaks, and I saw no bubbles.
The stock landing gear is usable, but not a quality product. But they will do the job.

Will have to trim some wood away in the wheel wells as the angle of the wheel interfeera with it.
Also, I will tr install the wheel well liners, so it will have to be trimmed anyway.
The gear doors screw onto the lower sizzer link, and an upper alu block. Nice solid system.
The construction and glue joints in the wing are pretty well done for a chinese ARF.

This plane is much better than the Bearcat and Spitfire I have from the same manufacturer. It is a newer kit than the others.