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Old Apr 30, 2014, 02:14 PM
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I wonder though, the hobby is so focused on electrics now. Nitro/gas heli's are becoming a smaller part due to the noise and learning curve. Plenty of us know the upside, but I wonder if the big players (OS, Thunder Tiger, Magnum) will put out smaller gasser engines.

On the other hand... the efficiency lends itself to UAV use... maybe that'll drive development.
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Old Apr 30, 2014, 04:06 PM
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Stinky linky, no findy windy, That links doesn't work.

Quote:
Originally Posted by cruzroy View Post
IS THIS TRUE.....Gasser engine for RAPTOR 30


New Gas engine from Go-Engine: GH-56G



http://nitroaddictsaustralia.com/ind...-3-d-heli.html

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Old Apr 30, 2014, 04:40 PM
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Quote:
Originally Posted by Chophop View Post
Stinky linky, no findy windy, That links doesn't work.
This one does: http://nitroaddictsaustralia.com/ind...-3-d-heli.html

This one is even better: http://www.go-engine.com/pdt_view.as...&area=9&cat=25

And this:
GAUI NX4 and NEW Gasoline engine Peter Test 1 (6 min 53 sec)


Brgds, Bert
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Old Apr 30, 2014, 10:32 PM
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Wow, the HP to weight ratio is very impressive. I may be late to catch a great deal on an abandoned Raptor 30 now. Looks great without smoke. I never really liked it.

Man does THAT thing ever say STAY AWAY better than a Totem Pole or skull on a bamboo pole !
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Old May 01, 2014, 01:30 AM
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Iwould not get too exited, because that power spec, 2.2 HP, is high even for a Nitro-burner.... so for a gasser, I simply don't believe it....

Apart from that, the video was posted about 1~2 months ago, and to be honest I have not heard anybody else about it. Unknow, does not mean, that it is a bad product, but there is no big company reputation like OS behind this engine....

I'd say: wait and see.... But if you can fit a .56 engine, running on gas, in a Raptor 30 (with its known very poor cooling system)and still keep that engine running without problems?????

What I find strange is that the manufacturer (second link my previous posting) does not state HP, and mentions 18000 RPM as practical RPM, and the first link, the australian sales advertisement, states a power of 2.2 HP @ 18500 RPM, and 21000 as RPM limit....

When you look at the ignition unit, it states a current draw of 750 mA @14000 RPM.
If the engine is that capable, why do they state that current draw at 14000 RPM, not at 18000 RPM?

I believe the engine is real, but I am not too convinced about its specs, and most, about its longevity if one would use the engine mainly under that load....

Brgds, Bert
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Old May 01, 2014, 02:46 AM
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But what I don't get:

Sparks work, also for Methanol. Smaller engines can be built with a roller bearing in the small-end.
Any glow engine can then be operated with far lower oil content (5% would not be any problem) and as such, glow engines can compete with gas for fuel prices, and with CDI even can compete with them for user friendliness...

I personally like methanol because it is less critical in adjustment and runs a bit cooler, and it does not stink up the house....

Brgds, Bert
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Old May 04, 2014, 01:22 PM
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Yesterday I damaged the engine of my .30 size mini Star Ranger, and upon investigation, found that ALL our CDI equipped helicopters suffered from overheating sparkplugs, leading to the engine igniting due to the heat in the plug, rather than the spark, in effect loosing the advantage of controlled ignition timing....

It seems, that the cooling of a spark plug due to the propwash, that fails in a helicopter (plug cap is enclosing the plug, but the cap is not subject to the cooling air flow) is needed to keep the plug temp acceptable....

I am now working on a design for cooling the plug....

I might be wrong, but I have the feeling, that all "gasser experiments" that failed earlier in this thread, failde because this loss of control over the ignition timing.
I am mildly optimistic, that once I can control the temperature of the spark plug, I will have regained control over the ignition timing....

Brgds, Bert
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Old May 04, 2014, 05:31 PM
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Maybe another reason some are calling for 25:1 oil mix. In addition to compensating for no roller bearing, it cools the plug.

I like the smell of gasoline engines a bit, but with additives like Lucas oil that dissolve combustion deposits, you get a better smell. Some must add scent enhancers, they smell really good.
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Old May 05, 2014, 01:26 AM
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Well.... for example Zenoah is calling for 25:1 and they ARE using a rollerbearing.
AFAIK Saito calls for 20:1 or fatter because they do not have a roller bearing.

But that is not the issue here:

we are running methanol, and roughly a 6:1 fuel/oil mix (15% oil)....

If oil would cool the plug, that would be sufficient cooling, so I guess, that is not the case...

In the meantime, I am working on a way to cool the plugcap....

It seems that the few T-rex 600 that we converted, when equipped with a high flow cooling fan, are not affected by this problem....

Brgds, Bert
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Old May 05, 2014, 03:36 AM
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Quote:
Originally Posted by Brutus1967 View Post
It seems that the few T-rex 600 that we converted, when equipped with a high flow cooling fan, are not affected by this problem....

Brgds, Bert
Just before I started to fabricate some elaborate heatsink for the plug, it struck me, that all engines that seemed not to be affected by the hot plug, were engines designed for higher Nitro. AKA engines with a relatively low compression ratio, and maybe with a less agressive squish.

So since I have still a few loose combustion chambers for the Rossi, I guess it is first more clever to reduce compression ratio....

So fire up the lathe!

Brgds, Bert
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Old May 05, 2014, 05:07 AM
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And.... big dissapointment: I enlarged the combustion chamber with 0.2 cc, which would estimated lower CR by about one point, but no, nada, zilch effect on the heating up of the plug....

In the same effort, I checked if the plugcap possibly would get hot, but it does not.... which means, cooling the cap is not even an option....

Back to square one....

Brgds, Bert
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Old May 05, 2014, 09:48 AM
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Please disregard previous message....

The problem is solved, but previous message was the ONLY condition in which it keeps running on auto-ignition: when after hoovering the heli is landed, and minimum pitch with Idle-up is selected: the tuned pipe keeps the engine on an artificially high RPM, and the closed throttle leans out the mixture.... ANY advance of the throttle, and the mix richens and it needs a spark again.
Any further closing of the throttle, and the RPM drops, the heat goes out of the engine, and it needs the spark again as wel.

But in ALL in flight occuring running conditions, the engine stops when the ignition is killed....

Brgds, Bert
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Old May 05, 2014, 04:22 PM
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Almost an advantage if that is truely the answer. It might help idle smoother and more reliable with a pseudo dual ignition, and may help keep the engine from loading up with gunk with the lean mixture. That is unless it's too lean.
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Old May 05, 2014, 06:07 PM
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I'm sure you've probably already thought of this but have you tried running a tad on the rich side, or possibly higher methanol content? Just throwing this out there.
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Old May 06, 2014, 01:24 AM
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For some reason, we could not richen up the mixure or the engines would start misfiring horribly. No idea what caused that.

That seems to have been remedied as well.

@ ChopHop: auto-ignition is never an advantage, since the only thing you know for sure, is that you have lost control over ignition timing.
It might have been, that the engine was firing on the spark under all conditions, and only after killing the CDI the A.I. would take over with ignition on a slightly retarded angle, but it can be very well that the engine was igniting well before the spark, which seriously engangers all the moving parts.

Definitely the engines were running a serious deal hotter compared to glow, and now it seems they are running more acceptable temperatures....

Brgds, Bert
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