combatpigg

My Feedback: (3)

I think you are correct. Nitro occupies space in the fuel and the engine's fuel demand rises with more nitro added. If the engine has less space inside to pass fuel into the combustion chamber, then the engine is able to match the lower demand for low nitro fuel.

tru168

Hi combatting.

Thanks for your explanation. No wonder it can run smoothly without nitro.

combatpigg

My Feedback: (3)

Tru..if the compression isn't high enough...then it wont run at all on zero nitro. The smaller bore engines require the most perfect fit between the piston and the cyclinder wall. Tiny scratches develope on both the piston and cylinder wall that create leakages.
So....adding nitro can possibly help prolong life to an engine that is partially worn out...?
There is a guy in Thailand who came here to show his hand built .049 throttles. They looked very good to me.
His name here was "Bugzidor".
I was surprised that he did not get any response from all the 1/2A flyers here who have been crying like little babies [for many years] for a good throttle. His throttle looked very good to me and he showed it on youtube..

tru168

Combating..my cox engine have little run time and been carefully break in, compression seems still tight. When it worn out one day, I might fuel it with 20% nitro fuel, or just change its piston and cylinder. I ordered a sure start and already on its way, want to see if it will perform well using 0% nitro fuel. The reason I keep working on 0% fuel is just because of I can't get any nitro fuel with castor contain locally. Our local sig champion fuel dealer closed down few months ago. I manage to find o'donnell 30% car racing fuel which contain 8% oil, I add extra 12% castor for my future used.
Since I'm flying sports and going to promote cox engines in our local club, good throttle is a must for me, and i need it badly, but throttle muffler seems expensive to me. Talking about the muffler, I will try to test the sound level and see if it meets our legal sound level without muffler.
I never heard about the Thailand guy, but really interested for what he did , and I'm try to google for more info. I might need your help to get some info in detail if I can't get any from google search.

Thank you.

combatpigg

My Feedback: (3)

http://www.rcuniverse.com/forum/m_97....htm#10163957\
tru168..hopefully this helps you.
I was really very impressed with his craftsmanship and engineering. His throttles looked very good to my eyes.

combatpigg

My Feedback: (3)

[link]http://youtu.be/KKtjxH7getI[/link]

Here is his link to youtube.
I do not think having a throttle for .049 is important to having fun...some people do think so.

tru168

Hi combatpigg,
Thanks for your link , beautiful throttle indeed! Already sent pm to the guy.Thanks!

For me, I already get used to 1/2a planes with or without throttle, but since I'm going to introduce cox engine to our local flying clubs, ( because flying site going smaller and smaller, can't fly with big gun but they still want to hear engine's sound and also the sweet smell of castor oil) most of local flyers still like to fly low , touch and go, and also throttle down for landing, they can always throttle up and fly another round if final line up are out of track.

combatpigg

My Feedback: (3)

tru...if more pilots learned how to fly RC with gliders..then having a throttle would not be an issue.
Too many pilots freak out when the engine dies and they think they have an emergency to dial 911 for.....
I used to fly 1.20 powered 4 strokes and rarely had any emergency landings that my glider experience did not help save.
People who rely on engine power to land their planes will never know the truth about simple flying.

tru168

Yes, you are right , most of them don't know the wing loading of model planes are actually not the same as real one, we can land our sport plane dead stick , in fact, it's easier to land than powered
landing. I think I will fly with them together and use unthrottled cox , let the engine cut and landed dead stick, to convince them .

combatpigg

My Feedback: (3)

It has been at least 12-15 years since I landed a plane with wheels...
It was probably a .45 sized 3D profile plane that landed at 10 mph with a 4 pitch prop.
Show your friends what you like to fly, but don't make it your responsibility to convince them how to have fun. Most flyers I know need big planes to feel the thrill of the sport. They think 1/2A is "cute"..but not for them.

GallopingGhostler

Agreed. Interesting that some people have the same attitude about motorcycles. Most important is having fun, who cares what others think? The 1/2-A's are just as fun and competitive, too.

GallopingGhostler

Most likely the reason why they dread flying dead stick, is they have never practiced it. Being a long time 1/2-A flyer, dead stick is a usual occurrence. The prettiest sight is seeing one's R.O. plane crabbing dead stick as it flies past cross wind prior to landing.

On rudder only, one learns control. Any time rudder is given, the plane drops its nose and picks up speed. If one times it right, they can flare upon landing and in very close proximity. [8D]

tru168

combatpigg,

Thanks for your opinion. several of our flying field forced to reduce its size, flying " standard " .46 size planes seems quite impossible right now ;-) they currently fly electric but start to search for small size IC powered planes. thats why I try to "convince" them :-)

combatpigg

My Feedback: (3)

It sounds like a really important thing is to be able to fly slowly and to kill the engine in case something goes wrong...! Big models [over 300 square inch wing area] with 6x2 or 6x3 props can help. People who live nearby [who do not fly] will get irritated by the sound of Cox engines.
Farmers will tell you the noise makes their cows give sour milk.

Mr Cox

Cox engines have a noise that tends to get on every ones nerves, I've never heard a nice one, not even the muffled ones like the cox 05RC. I think OS .10 and .15 LA are better suited then. These are very quiete (baffle in the muffler) especially when used with a little larger props.

Diesel engines are even more quiet, but are not for everyone.

tru168

combatpigg


Noise from cox engines become one of the problem here, several local flying site refused to let me fly cox engines in their field unless I can prove the sound level is under 94dB at 9 feet. ( legal standard ) I haven't test sound level yet, That's why I wanted to get a Dragonfly to compare with normal cox sound level. (I have a dB meter .)I bought one Dragonfly weeks a go but sadly when I received the dragonfly ( NIB) it have missing fuel tank back plate and also the most important throttle muffler already gone. Contact the seller and didn't get any reply.

Searching hard for one NIB Dragonfly recently without any luck, some wanted to sell their collection item to me at higher price which is too high for me.
Actually a few new cox engines already on its way , donated from some nice guys , to let me test and write articles / review / test etc.. for my coming new web page also local printed article, but no Dragonfly :-( .









[/quote]
It sounds like a really important thing is to be able to fly slowly and to kill the engine in case something goes wrong...! Big models [over 300 square inch wing area] with 6x2 or 6x3 props can help. People who live nearby [who do not fly] will get irritated by the sound of Cox engines.
Farmers will tell you the noise makes their cows give sour milk.
[/quote]

Mr Cox

The TT 07GP is a nice quiete engine too. A bit more power and nice throttling compared to cox .049 engines.

combatpigg

My Feedback: (3)

I've never heard a miniature [.049] diesel engine with a muffler....but I'll bet that would be pretty quiet.
I tried a Cox muffler once and didn't think it helped lower the sound very much.
Wide open land in Malaysia must be getting hard to find..?
There is still lots of it in Alaska....!

tru168

As you mentioned , farmers! their cows give sour milk !

actually not all because of farmers ;-) , years ago , one of local flying club member was hit by a .46 size quickie, and died. thats make few of our flying club reduce its field size to limit large rc planes flying around...

combatpigg

My Feedback: (3)

tru...that is horrible about the man who was killed. I admit to not liking standing inside the race course. I dont see how much good wearing a helmet can do with a 150 mph plane.

ffkiwi

....then you must never have heard of PAW, Schlosser, Davies Charlton-all produce/produced diesels in that range and all have mufflers-in the case of PAW and DC, since the mid 1960's.....! ........and yes they are fairly quiet-but that probably has as much to do with the prop sizes being turned and the revs produced, as it does with the effectiveness of the mufflers...................

ChrisM
'ffkiwi'

MJD

My Feedback: (1)

"Never heard them" is different than "never heard of them"..

I have a Pfeffer .036, sounds like a 5 year old going "brrrrrrrrrrrrrrpt" by blowing air through his lips. No bark to the sound at all.

GallopingGhostler

I can see why diesels are popular in Europe. They don't have a sharp bark and are more tolerated due to their lower noise output. Across the pond here, people have become more and more intolerant of certain noises.

Hence this is why I am glad I live out in the near boonies. I can run my engines in my back yard, houses are spaced roughly 150 feet (46 m) on center (all in my neighborhood have one acre or 0.4 hectare lots). The neighbor builds hotrods. It doesn't bother us if he runs his engines at night, because with the doors closed, we don't hear it. If we have a party in our backyard, it doesn't bother the neighbors.

The flying field a couple miles away is sparsely populated. The nearest home belongs to a farmer is 1/4 mile away. The next house is 1/2 mile away and so forth. Muffler a little noisy? No problem.

However, I know that doesn't help the rest. It is just a freedom I enjoy.

GallopingGhostler

Even the older unmuffled OS Max .10 RC baffle piston was quieter, when operated at less than full throttle. At half, it sounds muffled. At full, it sounds as loud as a Cox .049 reed valve. Compared with unmuffled larger engines (.19 and up, IMO), the Coxes noise doesn't travel as far. This is why AMA started recommending mufflers here in US in the early 1970's. Clubs were starting to lose their flying fields due to noise.

Problem with muffling .049's is the loss of horsepower. Most of the small planes are already underpowered when compared to their larger engine counterparts. About the most restrictive were the aluminum Tatone .049 mufflers, available back then. I still have one or two floating around. The least restrictive seemed to the the short lived Cox .049 R/C Bee engine that came out in the 1970's. It had a flexible silicon sleeve cover that went over the wide flanged exhaust restrictor sleeve. The top flange was wider than the bottom flange. The bottom flange of the restrictor was loosely fit, to allow the exhaust gases to escape.

The silicon sleeve lasted over 100 flights. I still have it. There is only a slight burnt rubber portion where the exhaust gases were strongest. Unfortunately, this is a hard to find part. The engine was only on the market a couple years then withdrawn, for the cheaper to manufacture Dragonfly engine that replaced the R/C Bee.

Bernie at Cox International had a discussion on mufflers. His current impression is that there are not enough market to support having him to recreate these parts (i.e., the Dragonfly throttle muffler / QRC engine muffler by contracting with a machine shop. I think if there is enough general interest from those contacting him personally, may sway him to do a limited test run.

I think this is where the Norvel 061 Big Mig and the Thunder Tiger GP-07 have their place. They have enough power even after being muffled, they come with an effective muffler.

Mr Cox

The Norvel .061 engines are anything but quiet at +20000 rpm, I've had big boys land their planes when I'm up with mine. Said he kept looking at my plane instead of his own...
The sound is a lot more pleasant though, as these engine run strong and smooth.