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HomeAircraftHelicopterGasser Model RC HelicoptersEngines › OS15 gasser heli
06-13-2013 10:10 PM  5 years agoPost 41
Justin Stuart (RIP)

rrMaster

Plano, Texas

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An electric 700 with 1000-1200rpm headspeed will have roughly the same performance as this motor in a comparable 700 nitro airframe, and with 12s 8000mAh packs will have a flight time in excess of 30 minutes--using packs which cost only $60 each. More importantly, the electric helicopter in all likelihood will last for several years without problem, while this OS15 gas motor has proven time and time again to fail--sometimes with only hovering.

I think the only thing that can save OS with this motor now is to cut the price to $350, and to start offering a Horizon Hobby-like no-questions-asked free repair/replacement policy. How else will OS lure wary nitro pilots into trying this motor given the well-published track record we have seen in recent months? Who is going to be willing to risk $500 with the full-knowledge that the motor can fail in as little as 2 flights, and that in the event of a failure, the modeler will receive very little warranty support from the manufacturer?

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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06-15-2013 07:36 PM  5 years agoPost 42
RM3

rrElite Veteran

Killeen, Texas - USA

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the motor is what it is........
I will take that as code for "its a piece of crap"

showing a preference will only get you into trouble, 90% of everything is crap...

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06-15-2013 08:06 PM  5 years agoPost 43
Carey Shurley

rrElite Veteran

Orlando, FL - USA

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no not at all
the motor is what it is........
its a 15cc gasoline motor that can be installed into most existing 700 class nitro helicopters with minimum modifications
I think at some folks are expecting either glow fuel or 30cc type performance out of it. Before this the smallest commercial engine designated for helicopter use was 20cc

Proprietor - Gas Powered Helicopters

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06-15-2013 10:45 PM  5 years agoPost 44
HP_CC

rrNovice

Asia

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I don't get it with people bashing this engine left and right.

Mine has almost the same performance as my OS70 on 15% nitro. Yes it bogs on most maneuvers even with a governor, but what do you expect?

It's easy to mount on existing 60-90 size helis, easy to tune when run-in, and it gives of the power of a 60-70 size nitro engine.

And I don't get it with people saying "Oh wait till you handle a REAL gasser!" or "A Zenoah (or something) will blow that thing away". I have a Zenoah 26 on another heli and yes it is more powerful but what do you expect with half the displacement? It's not aimed at people wanting to do hard 3D, rather it's for the "sport" flyers and people who have existing 60-90 size nitro helis that want to convert to gas.

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06-15-2013 11:37 PM  5 years agoPost 45
turboomni

rrProfessor

East of the Equator

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Sounds like you have had success with your OS. I think the big gripe is it has had so many failures,,blown pistons etc. Have you flown yours awhile? If so let others that are considering one know your tips for success.

Setup is everything, All my heli's can fly far better than I can pilot them

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06-16-2013 03:08 AM  5 years agoPost 46
Carey Shurley

rrElite Veteran

Orlando, FL - USA

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I've got 40-50 flights on them

the single most important tip is to not overheat them. They aren't any different than the Zenoahs, if they get too hot bad things happen.

Its harder to tell though, its a much smaller motor and you don't get a lot of warning. There is a change in the sound but another way is to install telemetry and thermal alarms

Proprietor - Gas Powered Helicopters

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06-16-2013 04:09 AM  5 years agoPost 47
Gearhead

rrMaster

Vt

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They aren't any different than the Zenoahs
Carey, sorry, I hate to disagree, but the OS really isn't like a Zenoah, the liner in the OS is steel (or brass) and it's not a part of the aluminum cylinder as in a Zenoah, so it will run hotter and cool slower when it's over heated than the aluminum cylinder in the Zenoah, and the Zenoah's have larger cooling fins, so the OS with it's Glow engine case (case) should have larger cooling fins

with that, RIGHT NOW OS needs to do something about that old type head that they have put on it,, OS can not think that we don't know why they put that old type head on it, like the Hyper 50 the next one will come with a larger CNC Head that cools better AND it will cost more, too, remember> OS is not manufacturing engines for fun, they are manufacturing them for profit

I know, I know OS is Japanese, they do things their way, and they upgrade things when THEY feel fit to, but I tell you if it was an American made engine it most likely would have never came with that type head on it, and if it did I bet there would already be a replacement CNC head made for it and sent out to every one that has bought one, same with the Piston Ring Pin falling out

Jim
Buzz Buzz Buzz

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06-16-2013 04:36 AM  5 years agoPost 48
RM3

rrElite Veteran

Killeen, Texas - USA

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...I hate to disagree
oh no you don't, thats a lie
It's not aimed at people wanting to do hard 3D, rather it's for the "sport" flyers and people who have existing 60-90 size nitro helis that want to convert to gas.
Ok explain why others say this:
From what I see a purpose built 550 or light 600 would rock and would have plenty of power for 3D with pennies a flight
.
.
.

...and these two sentences don't belong together BTW, its one or the other dude
Mine has almost the same performance as my OS70 on 15% nitro. Yes it bogs on most maneuvers even with a governor
good performance and bogging don't mix.

showing a preference will only get you into trouble, 90% of everything is crap...

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06-16-2013 06:05 AM  5 years agoPost 49
Gearhead

rrMaster

Vt

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oh no you don't, thats a lie
LOL,,, no it's true LOL
good performance and bogging don't mix.
true, but he did not say what size blades he is sporting,

with what I have seen in the vids, it's well powered for a 15cc Gasser, but also with how well it does performs with 690s/700 it will perform much better with 640s, surely it's to small for all-out wacking 3D with 700s, to add I do not remember seeing a vid of it 3D'ing with 640s

Jim
Buzz Buzz Buzz

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06-16-2013 06:34 AM  5 years agoPost 50
HP_CC

rrNovice

Asia

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Sounds like you have had success with your OS. I think the big gripe is it has had so many failures,,blown pistons etc. Have you flown yours awhile? If so let others that are considering one know your tips for success.
I didn't do anything special to tuning this engine.

It was a pain though to have the needles synced at first as I am used to the 3 needle YS/OS nitros. I have run more than 2 gallons on this one and left it quite rich but not so much that is misfires or vibrates more than it should. Something to consider also is that I can't seem to make it as smooth and not vibrate as my nitro engines. I'm not a gas expert so my senses aren't really keen on small increments towards lean and rich.

Another thing is the needles are really really sensitive, and to make it harder I am guessing this engine is less tolerant to hot runs as everything is smaller (bearing liner piston etc) so I just kept it at 115C to 118C. I am also guessing it hits somewhere to 125C on idle up, just a wild guess. Very small increments (relative to nitro carbs) can make a sudden change in temp, which is a bit weird since my G26 Zenoah isn't this sensitive in terms of temp. Maybe the OS isn't as run in as my Zenoah, not really sure.

Telemetry will help as stated by Carey. For the first gallon I was checking temp by landing it every now and then. I was so careful as parts for the engine are very hard to come by here.

With parts failure, I don't know why some people had those. Maybe they had bad batches of the engine or worse, their 2T oil may be inferior I dont know. I am no expert on this matter. These are all just my theories.

If it helps I have used Maxima brand and Motul brand oils at 25:1 with 100 octane gas (I dont use it for the 100 octane, rather its the only one available here without ethanol)

This video also helped me quite a bit on tuning this engine:

Watch at YouTube

I made the mistake at first to adjust the carb's high needle at hovering rpms before even reaching lean side on the low needle. This made the engine bog like theres no tomorrow on full throttle, high load climbs. And then I watched the video and looked at the manual's graph where it shows the effect of the low and high needles. It seems that the overlap of the two needles is very great in area. In the end, I had good to acceptable hovering to full throttle mixtures. But I would like to add that my engine doesn't run as smooth as the one in the video. I know I'm a bit on the rich side but would like to ask for the help of someone more experienced in gasser motors first as I think these engines require a more sensitive ear along with experience
Ok explain why others say this:
From what I see a purpose built 550 or light 600 would rock and would have plenty of power for 3D with pennies a flight
.
.
.

...and these two sentences don't belong together BTW, its one or the other dude
Mine has almost the same performance as my OS70 on 15% nitro. Yes it bogs on most maneuvers even with a governor
good performance and bogging don't mix.
I didn't say it was that good not to bog, I was saying is that it doesn't get left behind by OS60s or OS70s. I personally ditched my OS70 a few months back as I thought it wont be far off from 90 size engines.

Good performance is relative to what you're using. I am using OS105, YS91SRS so if I compare it to those, I would surely be disappointed. I can only imagine if I was an electric guy, I would be throwing this out pretty soon. Take it for what it is and for what it is made for.

Let me clarify: People with 60s and 70 size engines will feel at home with the power this engine produces. People looking for 91 to 120 size power on this engine (as well as G26s etc etc) will be disappointed. But if you're looking for something thats cheap to just fly out, stall turns, inverted flight, smooth sport flying etc and bolts on with almost any 60-90 size nitro heli on the market then this one will fill the bill.

I am not sure if OS targeted this for 3D fanatics, if they did then they are lying. But I am guessing they didn't.
true, but he did not say what size blades he is sporting,
I am using Align 690D blades which are a oversized for the GT15. I use gear ratios for 60-70 size though so it helps with the bogging, though some headspeed was lost.

Currently its on a Freya Evo but I have tested it on a TRex 700N. With the TRex 700, the 690s were ok and had acceptable performance. I just pulled it out since I prefer to have a more powerful nitro engine on my old TRex 700 (collective management is not one of my strong points). On the Freya the engine felt less powerful even with less pitch, but it was on the same league as my OS70 on 15% Wildcat with all the same equipment albeit heavier (because of the ignition module and another battery)

Right now my dad is the one using that Freya and couldn't be happier with how it's performing for what he does, which is mainly forward flight and hovering.

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06-16-2013 01:02 PM  5 years agoPost 51
dkm

rrNovice

sydney, Australia

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What gear ratio are you running on your Freya ?
And what sort of throttle curves ?
I am running 1650-1850 rpm on a 8.63 gear ratio (95/11)
and 700 fbl blades on mine.

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06-16-2013 02:24 PM  5 years agoPost 52
HP_CC

rrNovice

Asia

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95 tooth and 11 pinion, same as yours.

for Normal I have something like 0-15-25-40-100 (the 25 and 40 not very sure). the pitch curve I have is something like -4, 3, 9

I forgot what throttle curve I had for idl1, but the pitch curve is the same with normal for my dad's forward flight/flyout. Using an Align governor and a JR XG8, the governor's gain is at 70% which roughly gives out (or at least supposed to, I haven't tach'd it yet) 1720~ish head speed.

On idl2 the pitch curve is set at -10, 0, 10 and again I forgot the throttle curve but it was somewhere like 100, 50, (somewhere between 30-40, def not greater), 50, 100. The governor is set at 75% or 77% which should in theory give out 1800-1850ish head speed.

I am using the standard flybar Align 690D blades.

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06-17-2013 07:21 PM  5 years agoPost 53
RM3

rrElite Veteran

Killeen, Texas - USA

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I'll be honest, this engine went into a gasser market absolutely dominated by Zenoah...knowing that, you would have thought that OS would have better field tested this thing BEFORE having the masses burn up $500 to $1000 to be beta testers. That just leaves a bad mark on the future of this engine.

It would however be nice to have an alternative gasoline engine to the Zenoahs, but at least make it as reliable and cost comparative.

its just sad that I'm able to find way more bad stuff posted about it than good stuff.

showing a preference will only get you into trouble, 90% of everything is crap...

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06-17-2013 08:39 PM  5 years agoPost 54
dschertz

rrApprentice

Jackson, MI

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Most people will never post about the good. That is just the way it is.

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06-17-2013 08:57 PM  5 years agoPost 55
HP_CC

rrNovice

Asia

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^agreed

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06-21-2013 06:11 PM  5 years agoPost 56
HP_CC

rrNovice

Asia

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To balance things out, I just heard a fellow flyer had a piston skirt break off while in flight. The damage extended towards the crankcase as part of the piston skirt blew a hole while being stuck in between the crankcase and connecting rod. Don't know much about details except that his engine came from the same hobby shop as mine and is from the same batch.

Is it possible to break a piston skirt because of too high temps? I have had my Zenoah G26 quit (seize) in flight due to overheat but it I just checked everything and did some minor very shallow (due to scratches) sanding on the piston itself after and all is well up to now.

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06-21-2013 07:02 PM  5 years agoPost 57
RM3

rrElite Veteran

Killeen, Texas - USA

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I've been reading alot on those failures...
and it appears to me that the alloy for the piston may be an issue...oddly it seems to be closely tied to the temps the engine is exposed to during operation and breakin. ring locating pins falling out, missing wrist pin clips, pitting piston crowns, fracturing pistons, all this is unacceptable.

whatever issue OS is really having with this engine, needs to be fixed quick if they hope to put a tiny dent into a zenoah dominated market...

but when you can get a stock G20ei for $250 or even a hot G29ei for the same price as a GT15...

showing a preference will only get you into trouble, 90% of everything is crap...

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06-24-2013 12:38 PM  5 years agoPost 58
chuck1073

rrApprentice

North Stonington, CT

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I'm on a rebuilt GT15 in a Trex 700 now. The first incarnation of the engine failed after (I believe) a wrist pin clip came loose. I can't be sure since I never found the clip. Piston, ring and liner had to be replaced although the liner has damage light enough to be a candidate for reuse down the road.

I've got about 3 tankfuls of fuel through it now, running it very rich with a head speed of only 1450. So far so good! Running cool and sounding better with every run.

The needles are super sensitive. Barely moving one yields noticeable differences.

I'm taking my time and getting the suggested 2-3 liters of gas through it before I lean it out any further.

Trex 700N - Raptor 50 FBL - B450FBL - 130X - mCPxBL - AMA #998104

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06-25-2013 01:48 AM  5 years agoPost 59
Gearhead

rrMaster

Vt

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it sound like they need to change the taper on the needles so it's not so sensitive

Jim
Buzz Buzz Buzz

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06-25-2013 02:43 AM  5 years agoPost 60
RM3

rrElite Veteran

Killeen, Texas - USA

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++
taper on the needles
...that or the thread pitch...go with a very fine thread so that the movement in or out is much less per turn. OR it could be that the carb is a bit oversized to the engine ...

showing a preference will only get you into trouble, 90% of everything is crap...

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