w4sm

Brenner, Thanks for the suggestions and calculations! I'll mull them over when I have a little more time. I'm tied up this week and won't have time to take and post pictures of the setup until early next week. I did make a generous hole on the bottom of the fuselage for airflow. I'm not really concerned about the motor overheating as a I seldom run full power for more than a few seconds of vertical. Most of the time the power is at most 1/3 to 1/2. On landing after the 8.5 minute flights the batteries and ESC were just barely above ambient temp. The motor was only very slightly warmer. Not uncomfortable to keep your hand on it indefinitely.

marlin847

My Feedback: (23)

Reza you posted on 10/27/07 that you where going to check on the landing gear. I have had my plane for almost 4 months as well as many of us. Have you heard anything on the correct gear? 11/10/07

Rezagh

My Feedback: (73)

marlin,

I have no dates as when they will be here. On such matters please call QQAC directly as I can't be much of help. I don't get or want to get involved in contacting the OEM directly. Last time I checked, Wayne was going to send an email to the OEM to check the status on these. Current landing gear situation is not causing anyone to ground their airplane but I understand look is very important to some people and you have the right as well, however out of many that were sold I seem to see only 2-3 people that are way more concern and seem to have a hard time dealing with the landing gear toe look!

Please be patient and if your problem is part related make sure to call the company. Anyway, if I can't help you on the forum with your problem or question, you need to call QQAC for those matters or issues.

This would be my last post on landing gear until QQAC notifies me of the status of landing. Once I have more info and they are here, you will hear from me. I too hope we get to the bottom of this.

Reza

marlin847

My Feedback: (23)

Thanks Rezagh, you really have been great with all the info on this plane and different options to go with.Since you are in comunications with the factory more than we are if you could let wayne know which of the few on here would need attention they could call us. But I will call them. I understand that this issue doesnt effect the way the plane flys (which is great) but 400.00 is at the higher end for a 120 size plane and to have the horn issue and the landing gear issue i am sure QQ would like to make it right. But like i said Thank You you have been a big help on all aspects of this plane, the customer ussally doesnt have a person to question and to get the best options for a plane like QQ does it. thanks Again Marlin

Brenner

Well, I finally finished getting Yak put together. It's taken me a while because when we had the horn issue, I put the Yak aside and focussed on Pattern, but now it's finished. Anyhow, I just wanted to report that it came out at about 8 lbs without fuel, and the CG came out exactly as per spec. The only changes I made from stock were to replace the stock OS 120 AX muffler with a Bison Muffler, and to swap out the elevator pushrod for a longer one so that I could cant the horn back towards the front of the plane to linearize the elevator travel. The Bison muffler has two advantages. It's quite a bit lighter than the AX muffler, (thus the 8 lb weight) and it fits totaly inside the cowl, so all I needed to do was cut holes for the exhaust outlets.

overbored77

My Feedback: (11)

Hey guys, Great thread lots of info. My wife was going to order me the 49" electric yak
for christmas but instead ordered the 69" So now I am stuck with it.

I currently have an OS 1.20-E series Four stroke new in box
and a Magnum 1.20 four stroke used. Should I bolt one of these
in it or bite the bullet for a Saito 1.25 or 120AX? I don't have the funds for
a YS.

I also have a small stockpile of Hitec 5645 MG servos will these be OK?

CloudNineAviation

Hi Guys,

Got the kit last Fri and finally managed the 1.20 AX a couple of days ago...for some reason no one in the U.K. had the O.S.

How much lighter is the Bis Muf..?

David Leitch

Hi there.. If anyone is in a position to post the empty weight of the kit I'd be most grateful. The reason I ask is I have to go all the way from Sydney to the USA to pick up this kit, actually just visiting for business, and don't want to have something shipped to a hotel that turns out to be too heavy. I'm looking to do an electric version of this. Been casting around for the right size model for a month now for my Hacker C40 10XL on 8s and the only other thing is the Funtana X 100.

fish4100

I ORDERD A 69 YAK I LIVE 2300 ABOVE SEA IS THE 120 AX GOING TO GIVE ME THE PULL OUT I NEED FOR HOVERING

pinguecola

hello brenner,
i am from italy and i am going to assemble my yak with o.s.120 ax with bisson muffler. did you find any decrease in thrust with this option versus the stock muffler?[:-] i do noy like to destroy fiber glass motor hatch.
thank you francesco

asmatt2

Reza,

What type of spinner is everyone putting on this plane? I was thinking of a carbon fiber but what shape and size should i get?

Thanks!

Brenner

Sorry Francesco,

I never ran my 120 AX with the stock muffler. I installed the Bison right from the start. Seems plenty powerful though ..

fish4100

REZAGH . SORRY MY NAME IS JOHN I JUST GOT THE BEST PLANE I HAVE EVER HAD 69 YAK MY RAIDO IS JR6102 MY SERVOS ARE NEW 5645MG MY 1100JR PACK 5 CELL IS ALMOST NEW I WAS TRYING TO SAVE A LITTLE MONEY IF THIS PACK IS OK IF NOT WHAT WOULD BE OK WITH OUT SPENDING 112.00 ON A BATTERY
PS. I GOT THE OS 120 AX DID THIS MOTOR COME TO LIFE GOOD FO YOU??

Rezagh

My Feedback: (73)

Hello John,

Capacity of the battery is not ideal but it will work for 2-3 flights on the safeside. Just keep an eye on it. I think a 2000 would be a much better selection. And no you won't have to spend a fortune. NIMH batteries are really cheap these days

Reza
P.S. Your email does not say what plane, you are putting these servos in it!

Rezagh

My Feedback: (73)

3.25" P51 or Extra style. Don't use Ultimate style spinner, they don't look good on this plane.
Reza

David Leitch

A while back I asked for the empty weights but noone seemed to have the data. It always amazes me that manufacturers/distributors don't keep such data or are unwilling to publish it.

Anyhow I picked up one from Mikes Models in Oklahoma on a recent visit and carted it all the way back to Sydney, cost me $100 in oversize baggage. According to my scales the total of the bits in the box is around 80 oz, with around 16 oz tied up in the accessories. For the electric configuration I will go with (Hacker C50 10XL on 8S) that should give me an in the air weight of around 155 oz, about 10 oz more than I wanted. There should be plenty of power but a highish wing loading.

I will do a bit of a build thread on the other forum.

Brenner

I just ran your specs through MotoCalc, and according to its results you should be very pleased wih this setup. This is what it says:

Motor: Hacker C50 10XL; 1624rpm/V; 1.26A no-load; 0.0118 Ohms.
Battery: FlightPower 2500 (20C); 8 series x 2 parallel cells; 2500mAh @ 3.7V; 0.0065 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: Hacker Planetary 6.7:1 Gearbox; 20x10 (Pconst=1.16; Tconst=1) geared 6.7:1 (Eff=95%).
Airframe: Yak 54; 950sq.in; 157.4oz RTF; 23.9oz/sq.ft; Cd=0.056; Cl=0.47; Clopt=0.66; Clmax=1.24.
Stats: 213 W/lb in; 192 W/lb out; 23mph stall; 31mph opt @ 66% (56:45, 72°F); 37mph level @ 78% (41:21, 75°F); 3635ft/min @ 90°; -294ft/min @ -6.2°.

Power System Notes:

The full-throttle motor current at the best lift-to-drag ratio airspeed (64A) falls approximately between the motor's maximum efficiency current (54.6A) and its current at theoretical maximum output (1181.7A), thus making effective use of the motor.
The voltage (27.5V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.

Aerodynamic Notes:

The static pitch speed (61mph) is within the range of approximately 2.5 to 3 times the model's stall speed (23mph), which is considered ideal for good performance.
With a wing loading of 23.9oz/sq.ft, a model of this size will have trainer-like flying characteristics. It would make an ideal trainer, for use in calm to light wind conditions.
The static thrust (334.1oz) to weight (157.4oz) ratio is 2.12:1, which will result in extremely short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and vertical climb-outs. This model will probably be able to perform a hover or torque roll.
At the best lift-to-drag ratio airspeed, the excess-thrust (196.2oz) to weight (157.4oz) ratio is 1.25:1, which will give very steep climbs and incredible acceleration. This model can easily do consecutive loops, and has sufficient in-flight thrust for any aerobatic maneuver.

Rezagh

My Feedback: (73)

Great info Brenner. Thanks very much for sharing

Reza

pinguecola

thank you, brenner!
now i am in doubt. i have a saito 125 too, ( i bought it for another plane), i have seen a video it flies great. i do not know the better choice. [&o]
another question please. due to the extreme lightness of the plane , have you to balance to counter act the load of side mounted engine ? i noted the saito is far more tall, and it could be a problem. i think with the 120 and bisson muffler the problem will be less important due the fact it is less tall and the muffler is under the engine.
thank you
ciao francesco

pinguecola

rezagh, have you had to balance for side mount engine? is it the same with ys 110 and o.s.120 ?
thank you francesco

Brenner

Francesco,

I don't recall having any issue with the OS 120 AX. Any offbalance due to the motor wasn't enough to affect the balance of the plane.

Brenner ...

pinguecola

thank you brenner..
i am going to assemlbe:
saito 125
jr 8411
duralite or jr extra
i hope i will not have trouble about elevetor arm.
now i am getting some aliphatic glue on joints.
ciao francesco

Rezagh

My Feedback: (73)

Hi There,

No I never even checked the lateral balance. Didn't seem to need any when I was flying it!

Thank you,
Reza

David Leitch

Well I am struggling along with my build there is a thread in the sports plane forum on the other site. So far not too many issues, motor is mounted, cowl and hatch fittings done, surfaces have hinges installed and the control horns are in. In my not so humble opinion it would be nice if all the blind nuts, including those for the cowl and the hatch were installed at the factory. Not difficult jobs but done more efficiently there. This is just part of a view that the more ARF a kit is the better, at least for a flyer, not a builder. A beautiful kit to be sure and nice and light which is what I was looking for. Rudder is done, bit of an effort with the spacers at the rudder end. I need a better light in my garage.

David Leitch

Pulled a couple of late nights and flew the Yak this morning. Despite have the elevator servo trim and still worse the elevator itself reversed on high rates the model flew great for the 8 minutes or so I've so far had to trim it out.

More comment in the other forum and I will report back further once I get over the initial thrill but right now she seems to have tons of power, lands like a ***** cat and was stable in my version of a harrier. So its already ticked a lot of boxes. Only just enough clearance with the 20" prop and the plastic wing mounting screws are too long but what the heck. Also while I am whining its a nuisance to have to undo two canopy bolts every time you want to change a battery.

Overall and based on the very limited air time to date I'm thrilled.