boltor

Greg - have you done any work on this yet? any thoughts on how to build the box, what sort of stand off it needs?

thanks

vx570

Hi boltor:
I haven't done any work on mine for some time and it appears to fly well as it is, but it has always budged me that their is a lump of lead the nose, I also have a Great Planes Pitts Special that has a 3 ply box on the firewall and I am fitting a Zenoah 45 gas engine to it, to me it looks an easy job too construct the same sort of thing on the Yak, then attach the engine mounts to that, I would judge how far forward by the amount that you could bring the Cowl forward,

I also have an ESM Katana with the same problem, however I can't bring the engine forward because of the restricted Cowl, so it's stuck with a lump of lead up front.

If you have a copy of the latest Aussie RCM news number 93 with the Spitfire on the cover, on page 36, that's the sort of thing, and attach your OS91 engine mounts to it, then move your cowl forward to cover it all up.

Hope this helps.
Cheers Greg

boltor

thanks Greg - I'm a bit undecided too - it flies well, but annoys me to have so much weight up front. Will let you know how it goes...

boltor

Greg (and all),

Have done some basic calculations and it appears as though I would need to move the engine forward 58mm to provide an additional 184g of weight - this would maintain the current CG as is. Almost 6cm seems too much and it makes the cowl look a little silly (too far forward). The maximum reasonable movement forward would be 25mm - this would then need 84g of weight to be added, saving only 100g over the original 184g.

I'm not sure that this is really worth the effort - saving 100g...

any thoughts on this? anyone else moved the engine forward?

johannmicallef

hey guys,

uff last week I got work to do on the bench as I crashed my Yak[:@] while doing a 3cm low inverted harrier.It was a bit windy and first I did some prop hang and even touched it's tail then some harriers and afterwards as I came for an inverted harrier I was high,I did a circuit inverted harrier to get low and on the second one i was realy low,as I turned it downwind I felt it was going down so I gave it full down and full trotel but because I was low when I gave it down the tail touched the ground,ran for about 6m until the nose came down.Not much damage,just a clean cut on the tail and other small damages.

I will be working on it very much as I have a funfly 3D and I want to compete with it.[>:]It's a very gd plane,it fly like my old funtana s90 or even better,perfect 3D for my case.

pearldiver

glad to see this thread still running i've got mine but still in the box. johannmicallef, sorry about the crash...nway, nices pics esp the KE & inverted one!

johannmicallef

Yes your right right pearldiver,this had have been open for 3 years know but still on the move.Is that true,u have it on the box.Go and finish it as soon as possible,when you will touch it the first time in air your go crazy for it even if you don't fly 3D,this plane is awesome and try not to crash it like me as they stopped building it and parts of Black horse Yak 54 doesn't fit for some mm's.10qs for the pics,that one was my 4th flight with it and it was a bit windy and as you can see it is so easy to get used to it.
Hope you fly yours,and mine soon.hehe

pearldiver

project still on hold since i dont have matching engine. initially i planned to convert to ep but after considering few factors has to cancel it.

johannmicallef

ohh,I prefer engines more than ep.I run it with a Saito FA-125A,very powerfull.Hope u found one soon and happy 09 flying.

DfmNet

Anybody try this YAK with Thunder Tiger 91 4 Stroke ?

pearldiver

i just got myself the saito FA-125A johannmicallef, what prop size ur using?

johannmicallef

hello pearldiver,for 3d on my saito i'm running a 15x6 and i did even run a 15x8,they ara almost the same.even when i had it on my funtana 90 i was using the same props.
Have fun with that engine as it is great .If you would some help ask me.

johannmicallef

hi guys,i've just added a video on the web of my yak 54.Check it out and have funwww.metacafe.com/watch/2948765/phoenix_yak_54/

pearldiver

johannmicallef, nice video! couldnt wait to finish mine. maybe will maiden in 2 wks time. sure i'll refer to this thread if i need some help!

johannmicallef

10qs pearldiver.have fun building it and hope u take it to the air soon.Try to find a good mount for the saito as it has alot of vibration.A rubber mount would be perfect.im using the one with the kit but it already got lose 3 times and today i even found a missing bold.know i will do a lock not to be safe.

pearldiver

yeahh i already ordered a better mount. i dont trust the blue mount supplied since i already own few 40 size models from Phoenix (same type of mount supplied with the kits).

pearldiver

maiden last week. she flies beautifullly. take off & landings are easy. i still need to adjust the CG. mine come out abit heavy at the front. im using heavier/longer (customized) brass spinner nut & aluminium spinner. maybe i'll replace the spinner nut to a lighter/shorter one.

johannmicallef

hi pearldiver,
good to hear that.My cg is like 3" back or even more from what the manual says.What i moved was the rx and the battery + I have a regulator with it as I use Li-po.My spinner is made of aluminum too.Hope u enjoy it very much.Last week we had a multiplex aerobatic trophy and will doing my schedule and I was flying straight and forward I had an interference and it just turned to the ground.It locked for a short while and went behind the trees.Fortunately control came back and I manged to see between the trees and i had only the time to get it straight.The only damage was the tail wheel.The good news is that I manged to finish in second place

How was the the saito doing?what prop did u use?

pearldiver

woww ur so lucky to get back the control! CONGRATULATIONS on ur achievement, 2nd place even after getting the interference is something to proud of!
i like the saito 125, but i feel it lacks some punch (compare to my YS63). i've tried JXF 16x6 wooden prop & Master Airscrew K Series 16x6, giving me 8450rpm & 8850rpm relatively. Personally i like the MA better, more punch. i've yet to try APC, just wondering how's the performance against the MA. anyway what prop ur using?
just wondering, when u do the upright harrier, do u on the flap? if yes, how many percent do u set in ur radio? thanks.

johannmicallef

yea I know that,if it was 2.4ghz I would not survive the crash as till the delay that 2.4ghz has till it starts.
Yes even my for the beginning was a bit lackey but know is fine and perfect.I'm using a JXf 15x6 [link]http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5528&Product_Name=JXF_15x6_/_381_x_152.5mm_Poly_Composite_propeller[/link],that's what i found best or a 15x8 they act the same.For the upright harrier u do not use any flaps,just elevator and trotel to keep the plane at level,ailerons to keep it straight and rudder to turn but when your turning help it with some ailerons.

pearldiver

i've tried both on & off the flap during harrier...wing rock would be less if i switch on the flap. maybe i should adjust the CG first, might adjust the Rx battery from behind the firewall to bit aft. i also have the JXF 15x6 (also purchased fr HC)..i'll try this prop this weekend & see if i like it. have u tried JXF 16x6? thanks

johannmicallef

as your telling me this I will try it with flaps next week.never tought of it.On mine it wing rocks only when I turn,on stright line it's very few the wing rock.I will try to post a pic of my sett up so that u can see and I will give you the position of my cg.Yes,I had used a JXF 16x6,it very good but for 3d its not good for my toughts.

pearldiver

johanmicallef, i just realised ur prop is poly composite one. mine are wooden one http://www.hobbycity.com/hobbycity/s...Propeller_16x6. maybe i'll order the composite one & compare which one more suit to my flying. anyway, been busy these few days, managed to fly her few times this last weekend & this morning.
have u tried adding little spoileron?... less wing rock?

sandyjain

Hi Najee and all others in this Forum,

I am just about to start building the Ya54 63" from Phoenix - we still get this around in India !!

Questions/ help required:

1. The manual is silent on the distance of the engine - back of the spinner/ prop. to the firewall. How did you guys decide on where to drill the mounting holes on the mount ? I have chucked the stock mount for a GP 60-120 mount. I will be using the SK90 engine - similar to the OS91FX. There is a lot of discussion on the CG - hence this becomes important.

2. Any tips on the the reinforcements that may be done on the new ARF.

3. What is the ideal prop. for this model using a 90 size 2 stroke engine. The SK90 manual and advice from fellow modelers is that the engine should be peaked at 9500 RPM. These chinese engines have good low RPM torque.

4. Elevator servos/ pushrods - are these mounted symmetrical and using servo reverse on 1 OR are they mounted asymmetrical using Y cable.

5. Ideal fuel tank - preferably Dubro - for 91 engine, that can be fitted in this model. The stock tank seems very small.

I will be very grateful if someone could guide me on these.

Regards

Sandy Jain