Dr Crash

The receiver ......



The complete Plane......


Me with my and a friends Phoenix Extra....

Dr Crash

Get yourselves 120AX -- It rocks!!

plopes

Dr Crash, how does she GO...
LOOKS GREAT.

Dr Crash

I wrote this earlier Im just pasting again...


Alright so the Flight Report---


The day was Nice and cold with some cross wind in Noida. We started the engine and the spinner came loose because the engine back fired. Not a problem -- set it up again. The engine was not leaned to max. as this was the first flight.

I gunned the throttle and in less than 5 feet it was airborne. The speed was so high because of the 16x8 (akaram you were right -- 16x16would be better) that I was flying at little more than 1/4 throttle. It was the most amazing first flight -- Everything was just perfect. No trims required. So did some circuits and landed.

I did not add any extra weight on the tail -- it needs some as it is a bit nose heavy like 20 grams or so -- not a big deal.

So the second flight I did some knife Edge -- 4 points -- loops , Man loops are the best I have seen so far, knife Edge is Smooth Even High Alpha.

Third flight I tried Harriers', Wing rocked as the CG is little towards the front but It did it eaisly. I put full rates on the aelirons and the rolls -- Man it was like flying a Jet(Akaram = 3001's worked just fine). The best part was the vertical -- No words, it just keeps climbing. I want to try it when the engine is tuned to the max. performance.

Over all ........

This bird -- i cant imagine it with a 60 or a 90 two stroke . You need a 120AX but you need to handle the power well. Go for it ........
Oh all the landings were slow and crisp!!

I will have to give some more right thrust -- the provided right thrust is not sufficient. The best modification I made was the Battery Plate I made -- If you guys put 120 -- Install your battery there -- so you dont have to add massive weight to balance the Cg. Also I reinforced all the formers which were weak!


Cheers

FUBAR03

Can anybody get me the demensions of the firewall (ie hieght, width, and length to end of cowl). I would like to know if my Zenoah G20ei would fit in it without butchering the cowl too bad. I saw the pics posted earlier but i couldnt tell if the muffler would end up in the cowl or not. How do you all think this plane would perform with the G20? I am looking for scale aerobatics. I know it wont 3D, and have no intenetions of that. Thanks.

FUBAR03

^

bash-ace-RCU

My Feedback: (16)

Has anyone flown this plane with a YS 110? If so, what prop did you use? I'm currently thinking something in the 16-5W ~6 area. Don't want speed, just thrust and breaking.

maukaonyx

This plane looks pretty promising and it is only $129 at Airborne online right now, in the overstock section of their website. I have enough planes that fly similarly otherwise I would get one. Jon

SysmiX

A friend at our club have had this plane with a zenoah G20ei and he really liked the plane. Unfortunately he crashed on the first day. I recently purchased a used one, I am using a OS .61 FX and it is really underpowered. The previous owner assembled the plane with the zenoah G20ei and made just one flight. She had a problem with the RX and got scarred of the plane. The G20ei did fit in the plane without too much damage to the cowl, there is just one 2-3 cm hole for theexhaustand one for the air intake.

plopes

Hi, this plane is beautifull.
here is mine powered by OS 120 ax

SysmiX

Ok, I got the Zenoah G20ei and tried it this weekend. The plane flies nicely, I had to add less than 30g to the tail to fix the CG (the ignition battery is a little to the back, close to the CG). I am not an expert in tunning the engine but I don´t think it has unlimited vertical performance.

kryptonite

Hi all,

I got this plane since the overstock price is just too tempting to pass. The ARF quality is one of the best I've seen - certainly better than Hangar 9's which can be quite inconsistent.

I'm thinking of going electric - probably 1200-1400 watt range as I already have the motor + electric system ready. Alternatively I could go gas (will be my first gasser) - something like a RCGF20 from bphobbies.com and others. The RCGF20 is reported to be able to spin a 16x6 at 9000 rpm - which would be make it identical to a Saito 125.

SysmiX, the Zenoah G20ei and G26ei have notoriously high ignition current, which seems to be a bummer as that is the only drawback on an otherwise fine motor.

I don't have much time now to start building now so there is still time to decide between the two. I'm tired of all the sticky residue of glow motors.

eluminous

Hi all,

This is an old post but worth a shot...

Has anybody found a solution to the issue with the elevator pushrods being very tight. Mine are so firm that they flex the whole servo tray before it moves the elevator. And there are no real bends in the pushrod path at all. Have many people replaced them?

Steve

MrFollies

I picked up this kit a little while ago and am about to start putting it together. For me this will be a stepping stone to 50cc sized exciting models so I want to do it right.
To this end I have a few questions from people who've enjoyed this kit before me.

I am *really* torn on the question of what engine to use. I have OS 61 2s and OS .91 FS (pumped) engines available, but from what everyone else is saying the will be too small.
Looking in the OS 2S range of engines for an alternative I see the following options:

91FX - Discontinued but I can get one locally.
95AX - Expensive but looks like the best fit.
120AX - Cheaper than the 95AX and only a little heavier.

Most people will probably say go for the 120, but I have a few thoughts on that.
- It's *twice* as big as what is recommended. Surely that is just nuts!?
- How much faster will it drain the 380cc tank? If I get a bigger tank we are looking at even more weight.

If the 91FX or 95AX muffler pattern is the same as the 61FX (have to check this) then I already have a pitts muffler that I can use. That makes these engines suddenly more attractive
So, resisting the temptation to say "Get the big one". I was wondering what people thought about the 91FX and 95AX choices here. I want enough power to teach myself a solid range of aerobatic tricks, although I think I am happy to forgo hovering if I can do almost everything else.

The second part of my question has to do with "What would you change on this model".

I'm a little nervous about how the wings are kept on so I'll look at adding wing bolts but what else? I've read about the canopy and I hope that this issue has been fixed by now.
Did people replace the CA hinges or perhaps some of the linkages? I am also considering using dual servos for the elevators but perhaps that is overkill.

Let me know what you all think!

akaram

I owned 2 of these planes which I kept flying for over 2 years, I loved them, both ended up in mid-air collisions

1- I had the OS91fx on them with a slimline large volume pitts muffler, was perfectly happy with it, it would do anything with the 91 except hovering
(it did nice slow knife edges, harriers, rolling harriers, flat spins, ... and still I practiced hovering high, it would hang on the prop (apc 15x6) but not enough power to pull out from the hover. Note that I was flying at 1500 meters above sea level. Once I flew at sea level and the power was fantastic, I did knife edge loops with ease and would slowly recover from a hover !!! Before crashing it the 2nd time, I got a 120AX for it to try and have unlimited power for hovering but didnt have the chance to test it. But definitely if you can afford the 95 it should be the best ! forget about the 61 fx as a friend of mine tried it and it barely flew, was so sluggish, flew just as a low wing trainer not more ...

2- I did add plastic wing bolts on both models, this is necessary !

3- I hate using CA hinges, I used Great Planes plastic hinges for perfectly smooth moving surfaces, also I recommend using hinge glue for those and not epoxy. You will need a hinge slotting machine to enlarge the hinge slots.

4- You dont need twin elevator servos but definitely it is nice to have good servos on it and the rudder at least. I had the perfectly smooth and powerful JR DS8321 servos (9 kg-cm torque) everywhere. The elevator and ailerons would drop after switching off the Rx, just like on bigger models

5-I used blue loctite on the canopy bolts each and everytime I put on the canopy and also used to secure them with a small peace of clear tape, otherwise you lose it in the air !!!

Eluminous, what you are talking about is not an issue on this plane at all, you got something wrong. I used to follow the curvature of the plastic sleeve/guide and slightly bend the pushrods accordingly especially on entry and exit and lightly oil the pushrods or put a few drops in each guide tube, you should get a pefectly smooth system, it just requires a light touch !

MrFollies

Hmmm, so it's a choice between the 95AX and 120AX. The 120 has an included right angle muffler adapter which I am sure would give enough room to fit it up front without the need for an after market muffler.
That would make it cheaper and have the ability to use the default muffler.

I'm still concerned that the 120 will be too heavy and use too much fuel.
95AX = 567gr + 120gr = 687g (based on the weight of the 91FX muffler)
120AX = 650gr + 220gr = 870g

It's 180 grams difference.. Not sure what that means to a model this size.
Still have some thinking to do about this I guess...

Yeah I think I will do that as well. I think I read somewhere that you did this in front of the wing tube? How did you manage that?

I'll definitely consider it.

I have 2 spare HS-645MG servos that I had earmarked for the ailerons. For the other control surfaces I still need to get servos. I'll check these ones out.

Thanks for the help.

akaram

I believe using the 120 with the included OS muffler is not an option, that muffler is very heavy !!! If you are to use the 120 you have to get the Slimline Q Series Muffler O.S. 120AX http://www3.towerhobbies.com/cgi-bin...&I=LXUNU2&P=ML , this way power and weight in the nose will be excellent, besides the slimline will hide nicely in the cowling. I know you will say thats a lot of money and expensive ... but this is the hhobby I think you can purchase the 120 without the original muffler. Use a15x6, 16x6 APC or a 16x6 K-Series master airscrew and you will be perfectly happy !

As for the wing bolts, will try to send you a pic today, still got a fuse. just reinforce with 3 mm ply behing the wing-tube. Drill thru. Cut the threads directly in the wing plywood rib soaking the wood several times with thin ZAP so it becomes solid.

MrFollies

If I source it locally, I can get a pitts muffler (BCM I thbink the brand is) for the same amount as I save by *not* buying the muffler. Nobody reports overheating issues with the slimline?

Wow, would not have thought to do it that way. Pics would be awesome, thanks.

MrFollies

There is one more thing I was thinking about.

The 120AX is rated for 9500 rpm and the 95AX for 16000. The recommended prop sizes are about the same.

Call me crazy but if the smaller engine is turning a similar prop at 1.7x that of the bigger engine does that not transfer to more thrust? Or will it be the case that the smaller engine, although rated for higher RPM will actually not reach that under load?

The specs on the OS site confuse the heck out of me.

akaram

No, the Slimline Q series is a new muffler and it is specifically built to be very light and compact ! We tested it extensively and 2 friends are still flying with it, it is great ! The BCM look OK but I was looking at them , there doesnt see to be a BCM pitts for the 120AX, maybe I just didnt find it, there is one for OS 1.20, this will not mount on the 120AX, the 120ax exhaust port is quite different from all other engines so only a muffler built specifically for it will bolt to it. ask and make sure.

The 95 AX will turn a prop of the same size as the 120AX at much lower PRM thus thrust produced will be much less. The 95 is rated for a max of 16000rpm meaning that it can withstand high rpm and can be used with a tuned pipe on racing, high speed, pylon ... type planes where you usually use low diameter high pitch props which unload the motor and allow it to spin at high revs thus producing much lower static thrust but way higher top speeds. Note that 14x8 is specified for the 95, you can mount something like 12x10 etc, the lowest prop recommended for the 120ax is 15xX. If you allow the 120 to unload and spin at higher than rated rpm you can damage the engine.
BTW prop load factor = Diameter Cubed x Pitch x Square Root (Number of blades - 1)

Experiment with above formula, u will see how changing parameters of the prop changes the load on the motor.

The bolts I used are plastic 1/4 BSW. Tap with a 1/4 BSW tap, after having a 5.1 mm drill hole. tap only after you soak up the hole with thin ca and let it dry. Enlarge the hole gradually, start with 2 mm drill and increase the diameter so the hole in the wing and the fuse align perfectly. Note the soft washer on the plastic bolt, it will prevent the bolt from coming loose due to vibration, I cut it from a soft pad used to protect the receiver.

MrFollies

Thanks for the information about prop loads, I've been flying for about 3 years now and this is something that I've never really looked into.
My local shop does stock a BCM 120AX muffler but I'll probably order everything of tower so I'll go for the slimline. I like the idea that others use it without issue.

With regard to the RPM's, if I understand you correctly, you are saying that the RPM range that the manufacturer specifies have nothing to do with the performance of the engine. It's just what they insist are the safe operating ranges for that engine.
In other words, if you stuck a very small prop on a 120AX, it would probably rev out much higher that 9500, but do damage to the engine in the process. Does that make sense?

If that's true then this is important to make sure that whenever you change props, you do a RPM check to make sure you are not exceeding the engines limits.

When you used this setup, did you also screw in the wing tubes as per the instructions? I am tempted to skip that step and simply use wing bolts in front and behind the tube.

I was thinking about this last night and I thought of another idea. I am concerned about the vibration over long term causing the CA soaked thread to break. What about creating some sort of hollow wall anchor.
Perhaps I could cut slot slightly bigger than 1/16th in the ply, and then take a piece of 1/16th aluminum which is has been tapped in the middle to accept the wing bolt.

Then I could poke it in the hole (tied to something) and epoxy to hold it in place. The epoxy does not need to do much other than hold the aluminum in place while the bolt is tightened (and to stop it falling into the wing when the bolt is not connected).

What do you think?

If I go with the 120AX which I think I will, then I'll probably upgrade the hinges to robart style hinges. I've only ever used nylon and CA type before so I think this will be a good exercise in how to install those types of hinge.

eluminous

MrFollies,

You do know that tower is in the US? I noticed that you are in Oz... Just thought it was worth asking.

MrFollies

Yeah :-)

They are pretty good about shipping over here. I've used them a few times when the Aussie dollar is a position to make it worth my while.

akaram

Regarding Engine RPM what you said is correct but also note the below:

the 95AX is rated at 2.9ps @15000 rpm while the 120AX is rated 3.1ps/9000 RPM
This tells you that for 3D type planes where you normally use large diameter low pitch props that require quite some torque to turn, the 120 is a winner, it will give you the 3.1 HP or something close to it at those low revs ! whereas the 95 at the same low rpms with the same prop will generate much lower power, almost half !
Usually engines that develop high power at lower rpms have longer strokes thus bigger moment arm on the crankshaft, this makes it susceptible to damage at highrpms but gives a lot of torque at low revs.

As for the thread issue, you could of course fill the wing with anchoring epoxy compound, drill the thing and thread for 8mm bolts and hold everything together with 8 mm steel bolts just joking, seriously you dont have to do any of that, as I told you I am an expert with this plane 2 years flying, 5 or 6 flights/week and the holes remained solid and brand new ! Just do them right and yes do use the 2x3mm bolts at the tips of the wingtube as advised, it is better, always put a drop of thread locker each time u assemble the plane on those bolts, you will not have issues. Before drilling and tapping the holes on the wingtube, finish the wingbolts, secure the wings with the bolts, tighten the wings and then drill the wingtube holes, this way whenever u tighten the wings with the 2 wingbolts, the wingtube holes will align perfectly.

MrFollies

All sounds like good advice Akaram. Thanks very much.