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Old Mar 08, 2013, 02:50 PM
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winston mo
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I also looked at hobby partz those batteries were only a 140 dollars for the gen aces the sky batteries were alittle less but both of those batteries like to puff.
I've used them on my 400 watt planes and they havn't lasted very long while the thunder power seem to last for a few years.
I can't even get a season out of the Hobby kings nano techs.
Thats using 1800 3s on an omera 72 3DHS edge 540.
I have quite a few leccys along with glow and gas.
For me I don't use leccys above the 40/60 size.
The over 60 I really like the dle's and OS's like the dle 20 and the os 22.
Also lipos can be vary dangerous charging at 5 c
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Old Mar 08, 2013, 02:57 PM
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winston mo
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BTW an os 22 or 33 is far more dependable that any leccy in it's size just go to the electric section and you'll see fried esc, thrown magnets, burnt windings just to name a few.
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Old Mar 08, 2013, 06:30 PM
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Originally Posted by AA5BY View Post
I've a flying buddy who had been doing electric exclusively for the last two years but recently came back to gas with two planes, saying he simply missed the sound.
I do love the sound of infernal combustion engines! But if I ever miss that sound in my models, I just go fly my powered paraglider.


Mike
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Old Mar 08, 2013, 07:04 PM
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Latvia, Ventspils pilsēta, Ventspils
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Originally Posted by jetmech05 View Post
Something I need to say. IMHO gas has more power than glow, Never see a glow stand on its tail and accelrate in the verticle until power is pulled off....................
In the 1980's ...................... I flew a WOT4 with ST 60 ABC with pipe ... that used to rise OUT OF HAND vertically and just keep climbing till I decided to stop.

Second - tell your Indy and other Oval racers that Gasoline is more powerful than Methanol ............ I think you will get a 'rich response' !!

Nigel
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Old Mar 09, 2013, 09:14 AM
Jim in the Desert
United States, NM, Las Cruces
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Originally Posted by solentlife View Post
What size does gasoline engine become practical ?

That needs two separate sections ...

a) Size / weight ............. because of it's style / format - then it needs a medium size model and up to be abkle to justify the size / weight penalties. Small Glow engines beat it hands down in the small size models.

b) Running costs ............. this then falls to location more than anything else. For example myself in Latvia .......... at near $50 a time for 4litres of Glow Fuel .... a gasoline engine at $1.30 a litre becomes extremely attractive in ALL sizes ! A common 3S 2200 LiPo at $35 a pop ............ gasoline again.

Thank the stars - there are online sellers who can sell me LiPo's at better prices !! But in larger models - gasoline.

Nigel

Nigel, what gas engine would you use for a high wing trainer or cub, with 70" wingspan?
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Old Mar 09, 2013, 10:49 AM
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Originally Posted by solentlife View Post
Second - tell your Indy and other Oval racers that Gasoline is more powerful than Methanol ............ I think you will get a 'rich response' !!
throw your communist indy crap out the window and realize F1 still uses gasoline WITHOUT alcohol in it and all the largest engines in the world use crude oil.

gas has stratospherically more energy content
alcohol requires stratospherically less oxygen to be present to combust
alcohol resists detonation from high effective compression more than gas

you trying to make this argument is nonsense. power is nothing more than the effective dynamic compression in the engine. if you are bound solely by detonation in dynamic compression, then changing fuels can make more power. if you are not, you will loose power.





at what point is there no longer a power benefit for glow fuel in the engines we use? around 30-35cc. a DLE-30 wont keep up with my saito 1.80 of the same 30cc displacement. then again they turn slightly different props. the closest common prop is an 18x6. i can kiss 10,000rpm on the ground (at 600'asl) with a really hot mix of fuel and all the stars aligned, and its still got some room to unload in the air. a DLE-30 will do good to get to 9300rpm.

at what point is it more economical to go gas? well how much do you fly and you HAVE to mix your own gas, but you don't HAVE to mix your own glow fuel. You can mix glow fuel at $5-6 dollars a gallon here. Buy it from the local track & then add your oil to it at the house. Instant FAI fuel at 1/2 the cost. If you're running 20% or 30% nitro (or more) yes, glow fuel can be pricey! But if for every flight of a big 25-40cc glow engine I have, I fly a .40-60 sized engine (even more a 4-stroke). the cost comes back down.


you should look at what is intended to be flown also. on glow fuel:
you can readily fly everything from .049/.051's weighing less than half a pound to 9' 20 pound planes. i know i do...
the gas engines out there simply don't compete evenly on power at smaller scales paying for battery penalties. they're fine if you're going to mull about.
there are a lot of low clearance planes out there are not designed to swing the larger props slower turning engines call for (electric conversions run into the same issue!)


but thats just things to think about... for the performance, na gas doesn't touch glow under 20cc. 20-30cc its even enough to be competitive. 35cc+ 100% go gas 'cause you're wasting your time!
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Old Mar 09, 2013, 10:58 AM
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Originally Posted by Toysrme View Post
there are a lot of low clearance planes out there are not designed to swing the larger props slower turning engines call for (electric conversions run into the same issue!)
That's not true. With electric you simply select the right KV for the prop you want to run. High KV for small props, low KV for large props.
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Old Mar 09, 2013, 11:54 AM
Jim in the Desert
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Originally Posted by MikeCr View Post
I do love the sound of infernal combustion engines! But if I ever miss that sound in my models, I just go fly my powered paraglider.


Mike
Cool!

What's your top speed in mph?
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Old Mar 09, 2013, 03:53 PM
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Originally Posted by cloud_9 View Post
Cool!

What's your top speed in mph?
Speed in my case is 25MPH whether I'm cruising, climbing or descending. More or less throttle only makes you increase or decrease altitude. Powered paragliders range from about 22 to 30 MPH depending on total weight and the exact wing that you have. Powered parachutes which are very similar are a little faster, maybe upwards of 35 to 40 MPH but require much more power due to the less efficient wing. My engine is a 313cc 2 stroke of about 25HP. I've been flying now for a little over 2 years. It's a blast!


Mike
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Old Mar 09, 2013, 09:12 PM
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Originally Posted by cloud_9 View Post
Nigel, what gas engine would you use for a high wing trainer or cub, with 70" wingspan?
+1 on the question...

I just re-maidened a .60 size trainer with an OS 65 LA. It's been a year since I've flown glow and I had forgotten the slime. So the question remains...

The 10cc Evolution might be big enough...
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Old Mar 10, 2013, 12:45 AM
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I use a 17cc on a 72"ws sport plane with plenty of power. On a true trainer a 10cc would probably be enough 15 or 17cc would be more than enough.
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Old Mar 10, 2013, 04:13 AM
Jim in the Desert
United States, NM, Las Cruces
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Originally Posted by MikeCr View Post
Speed in my case is 25MPH whether I'm cruising, climbing or descending. More or less throttle only makes you increase or decrease altitude. Powered paragliders range from about 22 to 30 MPH depending on total weight and the exact wing that you have. Powered parachutes which are very similar are a little faster, maybe upwards of 35 to 40 MPH but require much more power due to the less efficient wing. My engine is a 313cc 2 stroke of about 25HP. I've been flying now for a little over 2 years. It's a blast!


Mike
Definitely cool. Have you tried flying your RC plane from your paraglider? Probably impossible but would be fun.
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Old Mar 10, 2013, 04:15 AM
Jim in the Desert
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Originally Posted by 600Bob View Post
I use a 17cc on a 72"ws sport plane with plenty of power. On a true trainer a 10cc would probably be enough 15 or 17cc would be more than enough.
Thanks. Is it this thread in which people have said that 10cc gas motors aren't that great, the 20cc engines are where the sweet spot starts....or was that another thread?
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Old Mar 10, 2013, 06:14 AM
222 km/hr Parkjet flyer
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Latvia, Ventspils pilsēta, Ventspils
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Originally Posted by Toysrme View Post
throw your communist indy crap out the window and realize F1 still uses gasoline WITHOUT alcohol in it and all the largest engines in the world use crude oil..........................
Where do you get of with that rubbish ? I was not rude or inviting such response.

Second - F1 is supposedly based on the original concept of ROAD going ... so historically has remained a Gasoline based sport. Has nothing to do with power levels of different fuels.

Third - Communist ............... that's really funny .... I must remember that one Tavarich !


Finally - Most of the largest engines in the world use FUEL OIL or even COAL SLURRY ... those that use Crude Oil have extremely limited range of operation and specifications on that Crude ...... How do I know ? I own a Petrochem Lab and Company involved in Fuels and blending. I am actually typing this reply sitting in a large Oil Terminal in Rotterdam having just superintended the sale and transfer of 150,000 Tons of Fuel Oil. Last month - I looked after over 1 million tons .............

What did you do ?



Nigel
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Old Mar 10, 2013, 06:24 AM
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Originally Posted by cloud_9 View Post
Nigel, what gas engine would you use for a high wing trainer or cub, with 70" wingspan?
Personally if you have good supply of Glow Fuel and costs are reasonable - I'd go 60 Glow ... but if like me Gasoline is the economic way .. then any of the 15cc such as the RCGF I have or even if model is light / floaty enough - the 10cc ... I assume it's a 60 engine size model ?

Problem is people try to compare direct Glow to Gasoline ... they really are two disctinctly different animals. I ran Glow for many years and achieved amazing levels with some .. my ST 61 AAc with pipe would hit 19000 rpm ... it melted the piston and crank later !! But that's another story.

Gasoline engines are better in my book as plodders. They generally have lower rpm and so swing larger or higher pitch props. They are heavier than glow.
If you want speed and flexibility in the sub 20cc bracket - Glow will win hands down ... If you want to plod around the sky economically - then 15cc and up is either 4str Glow or Gasoline.

I have a 53" biplane that in 1980's - I flew with a piped 61 .......... today I have another of the same and is being rebuilot with the RCGF 15cc Gasoline engine ... final decision is still pending though based on weight. I may just put the gasoline job aside for another project and fit a 61 glow.

It all comes down to what you want the model to do.

Nigel
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