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Gas Engines

Old 02-02-2008, 11:08 PM
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GTO Pilot
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Default Gas Engines

I am considering moving from 4 stroke glow to gas engines. Are sites/books available that would help me learn about gas engines, how to determine the correct size based on weight of the plane and how to size props?
Old 02-02-2008, 11:34 PM
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freeonthree
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Default RE: Gas Engines

Try the Aircraft Proving Ground. Lots of info there.
Old 02-03-2008, 08:30 AM
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Bob Pastorello
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Default RE: Gas Engines

Go to http://wildharerc.com/ in the "Downloads" section is a really outstanding article from Tom about "Getting Started in Gassers", and there is a lot of very good information in there. Another benefit is credible information within various forums on RCU and those other places, but not sometimes very easy to sort fact from idiocy.

Many people "test" using gassers, and NEVER buy another drop of nitro fuel again.....
Old 02-03-2008, 12:13 PM
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Default RE: Gas Engines

I was going to have a look, but all I got was "page cannot be displayed"
Old 02-03-2008, 12:43 PM
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Default RE: Gas Engines

Fixed link, sorry.
Old 02-03-2008, 01:11 PM
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Default RE: Gas Engines

That was a good article. The only thing that I disagree with is where he said that the ign and rec stuff be at least 12 inches apart. Maybe that was the old days. My rec and ign batts are an inch apart, and my switch/charge jacks are 1 inch apart, and I have no glitching whatsoever. Maybe im just lucky...
Old 02-03-2008, 03:24 PM
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Bob Pastorello
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Default RE: Gas Engines

Well, maybe you should just write Tom and correct him..... his recommendations are for 72mhz, and work with "FM", non-PCM setups. ON my 2.4 stuff, it doesn't seem to matter, when I ran straight FM it sure *did*. But, as everyone says that tries to offer advice.... consider that it is FREE, and that "YMMV".
Old 02-03-2008, 04:19 PM
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Default RE: Gas Engines

Correct him ? Huh ? about what ? Im on 72.450 (ch 33). I said it was a good article.
Im not saying he's wrong, im simply saying that I havn't had a problem with my spacing between system components, thats all. All of his info there was good, and had I thought about it, I may have done my setup differently. None of the two systems wireing cross over or around each other, I made sure of that, and so far, the only glitch i've had was due to a bad Traxxas 2055 servo I had on my throttle in the beginning.
Brison recomends full synthetic at 80 to 100:1, but i've been told that will damage my engine. Yeah right... Ive also been told, and read somewhere that my 6 volt NiMH battery will roast my CDI box because the the voltage is over 6 when it's fully charged, more nonsense. I've been told that I should use a voltage regulator, and Tom said it's best not to use them, I agree with Tom. Ive never heard of anything roasting because it got an extra volt or even 2. I have been a mechanic my whole life, and I also have a decent electronics backround, so I have to wonder about alot of what I read. I do pay close attention to everything I read out here, or anywhere else, but I don't always agree with it. Some yes, some no. On the oil theory, I did pump up to 80:1 from 100:1 for a test, and the plane still stays clean, so im fine with it, but I think 100:1 was just fine, so im going back to it. My elmers Brison 50 has been running 100:1 full synthetic for 4 or 5 years now, and it still runs like new today, and has never had a failure, and when we pulled the plug for the first time the other night, it looked very nice. No signs of overheating whatsoever. There was also zero carbon buildup on the plug, and thats very good. I believe the worst killer of 2 stroke gasoline engines is carbon, not the lack of lubrication. Over the last 30 years, most of the compression lacking gas 2 strokes i've worked on had carbon issues. The carbon builds up and starts breaking loose, and it gets between the cylinder and piston, and in the ring land, and it dies a slow decreasing compression death. I guess we all have our theories, but mine are mostly from my own experience as a mechanic over a 30+ year period, and an RC pilot for 6. Just like my recent experience with the widely suggested 16x8 prop for my 26cc gas engine. Boy was that a waste of time for me. The benchmark prop for SV26 in my opinion is an 18x8, and so far, I have recieved at least 20 emails from people thanking me for that discovery. I don't care what kind of flying you do, it's silly to run any engine beyond the power band, period. All you get is more noise, more engine wear, less fuel economy, and less grunt to get you going.
Im not in this hobby because I love planes, I just love engines. Engines are my life, and repairing them for others has been my career for roughly 36 years. I think I understand internal combustion engines and the theory of their operation better than most folks who have been doing other things for a living.

Old 02-05-2008, 08:58 PM
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Default RE: Gas Engines

Many thanks Bob. I printed the paper and will attempt to digest it over the next few days.

Goats do fly!
Jim
Old 02-05-2008, 09:55 PM
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Default RE: Gas Engines

Glad to help, Jim.
If there is anything I can do, please email or PM.... gassers are GREAT !!!!!!!!!!!!
Old 02-05-2008, 10:05 PM
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Default RE: Gas Engines

Don's Hobby Shop also has a book on giant planes and gas engines. Lot's of info in it.

Regarding ignition systems and component spacing. There are a lot of methods that work most of the time. The manufacturers try to provide installation information that should work all the time. When I have doubts or questions I seek out the people that design and make the ignitions, generally Terry Grant at CH Ignitions and Ralph Cunningham at RC Ignitions. There are several more that are specialists in their field that are well worth conversing with. Listen to them first.
Old 02-06-2008, 08:41 AM
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Default RE: Gas Engines

Those are two really nice persons to deal with either for business or for just getting some information. Sometimes I give a guy with initials PR a hollar as he knows a thing or two.

Karol
Old 02-06-2008, 09:37 AM
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Default RE: Gas Engines

As far as the 12" rule... has been a rule for quite some time and has nothing to do with the "old days" With 2.4 it is much less an issue.. FM / PCM it is worth listening to the people who design the products and following their guidelines. Sometimes it's not always possible to follow the 12 in rule.. but it is good to follow it if possible.

As far as the 6 volt thing on ignition, #1 There is no benefit to using 6v. #2 TKG ie: Terry from CH has stated many times on here in the last couple of months that in his testing at 6v components start to heat up and will ultimately shorten the life of your ignition. By How much? who knows.. but they are still recommending 4.8 packs unless you have the modified 7.4 ignition from them. Of course there are some brands out there that will handle that stock, 3W is one of them.

In short, never assume.. ask people in the know... some of them have been mentioned already, however there are countless threads on here dealing with gas engines.. there isn't muchyou wont find if you play with the search fucntion for a bit. Sometimes it's not the most accurate but a couple trials and you can find almost anything you want. Most times someone has had the same problem in the past and found the solution already for you.


on a side note what is YMMV?
Old 02-06-2008, 09:46 AM
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Default RE: Gas Engines

To switch to gas; Every piece of fuel line and stopper needs to be changed to either Tygon or Neoprene. Evan the stopper in the tank needs to be replaced with a gas compatible type. Otherwise the gas will disolve them.
The engines run very much the same and sound pretty much the same. They both have an idle adjustment screw and a high speed screw. The main difference is the gas engine has a built in fuel pump.

Search these topics here to read up on gas engines. Also you can go to Tower Hobbies website and pull up airplane build manuals to see what instructions are given for installing a gas engine in their planes.
Magneto
CH ignitions
Gas stopper
Gas tank vent line
Diaphram
Engine standoffs
Old 02-06-2008, 11:14 AM
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Default RE: Gas Engines

Greg has been using 6 volts for years, and so are 4 or 5 other guys here in town. Im stickin with 6 volts thanks. If a 6 volt device cant take 7.5, it a piece of junk to start with and made with cheap components, and I would get a better one. Gregs C&H box has been on 6 volts for years.
Old 02-06-2008, 11:18 AM
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Default RE: Gas Engines

How do I delete this post ? It's a duplicate
Old 02-06-2008, 11:27 AM
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Default RE: Gas Engines

You shouldn't encourage going against what the manufacturer recommends because of your first gas engine plane it works for you and has worked for a few on your buddys. There are hundreds of posts here that show the exact opposite. 12" has been a rule that has worked.. as I said its not always possible.


Edited by Rcpilet:
Edited quote in reply to deleted post.
Old 02-06-2008, 12:21 PM
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Default RE: Gas Engines

Look, all I know is that Greg has a C&H CDI on his Pitts, and has been using a 6 volt batt for years. I have one on my SV, and neither of em even get warm. Several of our other friends use 6 volts too. Point is, were not worried. Thats all im sayin, ok. You do what works for you, and we'll do what works for us. My box pulls almost an amp at high rpm (700ma plus) and I dont want a 4.8 batt that needs to be cycled, nor do I want a lipo in my gas plane. I have my reasons. I would rather buy another box, should mine quit, and I know of noone who has had one give up around here, and there are several. Ours dont even get warm on 6 volts.
This argument is over...
Old 02-06-2008, 12:55 PM
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Default RE: Gas Engines

Show me where I told anyone that they should use a 6 volt NiMH 2000ma battery please. I don't think that I ever did. All I have done is share our experiences. Mine does a fine job, and so does Gregs and several others at our flying site. Maybe were just lucky...
Old 02-06-2008, 08:11 PM
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Default RE: Gas Engines

The original poster asked for help on his FIRST gasser.

The BEST thing that more experienced modelers could do to help him, would be to recommend that he follow the manufacturers recommendations when getting used to these new engines. He's a glow guy. He wants to get his first gas engine (I'm betting it won't be his last ). The BEST chance that he has at success, is to follow the manufacturers recommendations until he has a couple years of gasser operation under his belt. That will just about ensure 100% success for him. And we WANT him to be successful, don't we?

Making blanket statements that you are NOT following the manufacturers recommendations isn't really helping the newbie. It just creates confusion for him. It might be working for YOU, but wouldn't you be helping him the most by simply telling him to "follow the directions"?
Old 02-06-2008, 08:26 PM
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Default RE: Gas Engines


ORIGINAL: Jake Ruddy

As far as the 12" rule... has been a rule for quite some time and has nothing to do with the "old days" With 2.4 it is much less an issue.. FM / PCM it is worth listening to the people who design the products and following their guidelines. Sometimes it's not always possible to follow the 12 in rule.. but it is good to follow it if possible.

As far as the 6 volt thing on ignition, #1 There is no benefit to using 6v.


on a side note what is YMMV?
Your Mileage May Vary

Meaning if you do the same thing that I do, you may get different results, because EVERYTHING varies between setups, almost.

And - the "12 inch Rule" really has it's roots in poorly-shielded (or completely unshielded) *magneto* based ignitions from long-past days of yore.....about the same time someone conclude twisting servo leads and putting ferrite "beads" on them actually improved performance....

Kinda like the little plastic jugs of crap to put in your car engine that guarantees 10% mileage boost.....yep, YMMV....
Old 02-06-2008, 08:40 PM
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Default RE: Gas Engines


ORIGINAL: Bob Pastorello
Kinda like the little plastic jugs of crap to put in your car engine that guarantees 10% mileage boost.....yep, YMMV....
Those don't work?!?!?! [X(]

*^&#!@&^*) [:@]

[sm=lol.gif]
Old 02-06-2008, 09:59 PM
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Default RE: Gas Engines

I give up you guys, I have talked to my friends tonight, and were all switching to 4.8 volt 2000ma or better NiCads. You win... Better to be safe than sorry as they say. I already switch to 80:1 from 100:1 also. Brison say either is fine, but then this isn't a Brison. I thought I was alot more stubborn than this though. Thanks for all the info, were gunna follow it.
Old 02-07-2008, 09:44 AM
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Default RE: Gas Engines

ORIGINAL: Rcpilet

The original poster asked for help on his FIRST gasser.

The BEST thing that more experienced modelers could do to help him, would be to recommend that he follow the manufacturers recommendations when getting used to these new engines. He's a glow guy. He wants to get his first gas engine (I'm betting it won't be his last ). The BEST chance that he has at success, is to follow the manufacturers recommendations until he has a couple years of gasser operation under his belt. That will just about ensure 100% success for him. And we WANT him to be successful, don't we?

Making blanket statements that you are NOT following the manufacturers recommendations isn't really helping the newbie. It just creates confusion for him. It might be working for YOU, but wouldn't you be helping him the most by simply telling him to "follow the directions"?
Just a thought or two after reflecting on my own transition to gassers and right now trying to help my brother do the same.

As a rule, I prefer to follow manufacturer recommendations but there are conflicts which arise when trying to do so, i.e. you get a model that comes from the manufacturer and it is designed for a gasser with the servo mount for the throttle servo right in the engine box. They publish instructions on where to mount things and flight test information for the model using their install locations. Now what recommendation do you use? The radio guys in the pubished info from at least one manufacturer I can think of, still say 12" between those two. So do you redesign the model to accomodate that?

Now this "how close can the throttle servo be to the engine or rx?" question has been beat to death around the forums with some saying you HAVE to use the 12" "rule" and others like myself having no problems with the throttle/choke servos within 4" of the engine and batteries within 12" of the rx, so who's right?

Then there is the "where can I put the batteries/switches?" debate. Same 12" recommendation from some while others use different criteria mostly due to the size/configuration of the model being assembled doesn't allow for those kind of distances.

I tend to agree that a lot of the impetus for the 12" rule was as Bob mentioned since I kind of violated it right from the start using 72MHz radio stuff and things worked out just fine. Now the 2.4GHz radios offer even more resistance to RF interference from various sources, but you can still get bit if you don't do a clean install and pre-flight range checking.

So I would suggest he do some more research like he's started doing with Tom's article and the handbook from Don's helps as well, but some of that information is dated. Then dig around the forums and ask questions, that's what I did and it really helped getting the input from others who've already done this stuff. It's not too hard to figure out which way to go after doing some research and seeing the various replies. You'll eventually see a consensus of opinion on what to do, and it won't take long to figure out who really knows what they are talking about either. Just remember that with very few exceptions, there is more than one way to do things.

And here's the disclaimer; JMHO, YMMV...

Old 02-07-2008, 04:45 PM
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Default RE: Gas Engines

Zeeb - ROTFLMAO


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