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 موسوعة صناعة الأسلحة

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مُساهمةموضوع: موسوعة صناعة الأسلحة    الثلاثاء نوفمبر 12, 2013 1:28 pm

تذكير بمساهمة فاتح الموضوع :

 
موسوعة صناعة الأسلحة
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في ظل الحصار الجائر من الغرب والشرق على دخول السلاح الى الداخل السوري
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:33 am

[size=32]هيلوكابتر تعمل بالغاز[/size]

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:34 am

rc helicopter homemade



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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:35 am

[size=32]محاولة جيدة[/size]

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:35 am

RC Turbine Helicopter Basics


RC turbine helicopters are actually not very different from our gas or nitro RC helis with the exception of size (perhaps) and cost (most definitely). They are not enormous, pretty much the same size as larger gas helicopters or 700/800 electrics with rotor diameters in the 2000-2500mm (80-100 inch) range. Most will weigh in the 20-30 pound range so they are heavy buggers compared to equivalent 700 or 800 size electrics at roughly double the weight. You notice that weight in flight and have to fly accordingly - thinking ahead in other words.



As far as controls, mechanics, and how they are built, RC turbine helis are pretty much exactly the same as gas or nitro RC helicopters. Many of the larger helicopter kits on the market that have been designed to run gas engines can be fit with turbine engines with minimal modifications.
Wren for example, offers conversion kits to fit their turbine helicopter engines into several popular large gas and nitro RC helicopter mechanics.
The main differences between turbine powered and gas or nitro lie around the systems required to keep a turbine engine running such as the turbine engine's FADEC, electric fuel pump and valves, larger fuel tank/s, UAT (universal air trap), auto start motor, and perhaps a dry sump oil system for gear box lubrication.
All these extra systems use quite a bit of electrical power and require a dedicated battery pack over and above the normal receiver battery that we are all used to. Speaking of receivers, the radio equipment, servos, gyro are the same you would use on any large nitro, gas, or electric radio controlled helicopter.
One of the biggest differences I found between a turbine powered RC helicopter over gas or nitro internal combustion engines is just how smooth and vibration free a turbine engine runs. They are very much like an electric motor in that respect and have that same "feel" while flying. No reciprocating mass of a piston going up and down and no exhaust pulse, only silky smooth power - and lots of it! :-) No tuning hassles either as the FADEC controls engine management perfectly every time from start up to shut down! So yes, there are certainly some "tangible" performance benefits over the obvious ones that just stimulate the senses.
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:36 am

HOW DO MODEL TURBINE ENGINES WORK?
كيف هو يعمل التوربين



The principle of how model turbine engines work or any turbine engine is very simple. They suck in lots of air, compress it, add fuel to the compressed air, and then ignite the compressed air/fuel mixture. Seeing that the air is so highly compressed, more fuel per volume of air ratios are possible - this is why turbine engines are so powerful.
Igniting this already highly compressed air fuel mixture causes it to expand very quickly and seeing that there is highly compressed air at the front of the engine, this hot expanding air takes the path of least resistance – out the back end of the engine.
As the hot expanding air exits the back of the engine, it is forced by the turbine blades. This causes the turbine to spin and since the turbine blades are connected directly to the compressor blades by means of a shaft – the compressor spins and the whole cycle starts over. In other words the entire process is self sustaining.
The more fuel that is added, the hotter and greater the expansion of gas will be, causing the turbine to turn even quicker, thus sucking in and compressing even more air. The end result is lots of hot compressed expanding air exiting the back of the engine = THRUST!
You might be scratching your head right now thinking... "I understand all that, but how do you get this self sustained process going. If you just add fuel into the combustion chamber and ignite it, the hot expanding air will exit both the front and back of the engine?" That is a great question and you are absolutely right. The engine has to be spinning to create high enough pressure at the front of the engine so the hot expanding air can only exit out the back and past the turbine.
For model jet engines, this "pre" spinning is accomplished by either blowing compressed air into the front of the engine by say a leaf blower, spinning the engine with an external high speed electric starter, or by installing a permanent electric motor to the front of the engine. This electric motor uses a cone type engagement clutch so the only time it's mechanically "connected" to the output cone on the front of the compressor shaft is when the electric motor is powered up and spinning. The torque from the spinning motor pushes the clutch halves together and once the turbine starts, the motor shuts off and the clutch halves move apart and disengage. This prevents the small electric motor from spinning with the turbine which would destroy the small electric motor considering the speeds the turbine spins at (upwards of 160,000 RPM).




As you can see from this cut-away view of a Wren turbine engine above, most of today's commercially available model turbine engines are of the centrifugal-flow type. These engines use a single large centrifugal compressor blade to "throw" accelerating air outwards into the the convergence (compression) zone of the engine. This design is light and provides good compression efficiency from a single compressor blade. Simple & light weight, with very few moving parts compared to an axial-flow compressor with multiple smaller compressor blades to achieve compression efficiency.
Here is good good write up on the de Havilland Goblin full size centrifugal-flow turbo jet engine. It is a good read if you want to understand more about centrifugal-flow turbines and see how similar the scaled down model variety are (there is a good cut-away photo). Other full size centrifugal-flow turbo jet engines include Rolls-Royce's Derwent and General Electric's Allison J33 which powered popular jet fighters of the day such as the Lockheed P80's, Sabb 21R, and the Fiat G80 to name a few.
The picture below shows a Wren electric start turbo jet engine. The pod sticking out the front of the turbine encases the high speed electric motor to get the turbine spinning. Also notice this engine has screening around the intake. This is to protect the model turbine engine from FOD (foreign object debris).




Once the model turbine engine is spinning, only then can fuel be added to the combustion chamber and ignited. Now the next thing to realize is that in order for the fuel to ignite, it has to enter the combustion chamber in a gaseous state, not liquid. This isn’t a problem once the combustion chamber is hot – the liquid jet fuel (kerosene or Jet A) will vaporize as it flows through the combustion tubes and is introduced to the high temperature air. It is however a problem when starting a cold engine.
To solve this cold start issue two methods are currently in use. The first method is to use propane or a propane/isobutane mixture as the starting fuel source. This "starting gas" is already in vapor form (at atmospheric pressure) so a glow plug can ignite the air fuel mixture, this gets the engine started and warmed up.



Once warmed up the propane/isobutane is turned off by the electric gas valve and the kerosene is introduced as the primary fuel source by turning on the second valve and fuel pump.
[size=13]The picture above/right shows the two electrically controlled starting gas and main fuel valves used in an auto start model turbine engine.

[size=18]The other method of starting a model turbine engine is by using what is known as a "KEROSTART" system. This type of starting system does away with the starting gas and uses the main fuel source (jet A or kerosene) to start the engine. A small ceramic pre-heater/ignitor is used to vaporize the liquid kerosene and then uses a high voltage electronic sparker to ignite it. The advantage to kerostart is you don't need to have starting gas and it sounds more realistic. There is no "propane pop" on startup, but instead the all too familiar "tic, tic, tic," of the sparker just like you would hear in a full size turbine powered helicopter).
The draw backs to kerostart is does cost more than the starting gas method and in cold weather can be problematic to get started but they are improving. The ceramic heating element can also fail and it costs much more to replace than a $10.00 glow plug. Both systems work well so it depends on what you deem more important (saving a few bucks and dealing with starting gas, or having a more realistic sounding startup and perhaps run into a few starting issues when ambient temperatures are lower).
[size=13]Here is video that shows an autostart kerostart sequence... They usually start much quicker than this (10 to 15 seconds), but I'm sure since it's a brand new build, there are some fuel ramp parameters to be tweaked or the lines needed to be primed.


[/size][/size][/size]
Now when model turbine engines were first introduced about 10 years ago, all this switching of fuel sources and getting the engine spinning to a self sustaining speed had to be done manually. Once started, only then would the FADEC or ECU handle the fairly simple task of controlling the fuel pump to adjust the speed of the engine and monitor engine temperature.
Today's model turbine engine ECU's control everything from starting to shut down, making model turbines much more reliable and safe. This type of complete on board starting is called "auto start". It costs more than a manual start system and adds more weight to the RC turbine helicopter or airplane, but makes starting a turbine engine very easy and safe - very few if any model turbine engines theses days use manual start systems.
Now the next hurdle is getting all this model jet engine power to spin the main and tail rotor blades on our RC heli
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:37 am

UNDERSTANDING THE DIFFERENCE BETWEEN TWO STAGE TURBINES AND DIRECT DRIVE TURBINES

Two stage turbines and direct drive turbines – the two ways model jet engines convert thrust into horse power and torque.


After learning all about how model jet engines work, we now know they spin very fast and produce lots of thrust. This is fine for a RC jet powered airplane that relies on thrust to push it through the air, but a RC helicopter needs to spin a rotor - we need rotational horse power called torque.

Direct Drive Turbines
The first method of converting turbine thrust power into rotational power for a RC turbine helicopter is to extend the turbine/compressor shaft out the back or front of the engine and attach it to a gear reduction box.
The gear reduction box then reduces the input shaft speed of around 150,000 rpm by about 10 times. This means the output shaft speed is in the range of 15,000 rpm – the same as a nitro engine.
This is the least expensive way to convert turbine power to rotational horse power, but there are some serious problems with this method.
First, all the thrust that the turbine produces is wasted since it is simply just blown out the exhaust nozzle/s. This wasted thrust also pushes your helicopter around so you have to use up even more power to compensate for the push of the thrust.
This leads to the biggest problem of direct drive turbines, they are very inefficient. Most of the power (about 80%) is just blown off. Short flight times and huge fuel tanks are the result.
Direct drive turbines are on the way out as far as I am concerned. The top model turbine manufactures have started getting away from direct drive and most only offer 2 stage turbines now.

Two Stage Turbine Engines
A two stage turbine is exactly what is used on real helicopters and real turboprop airplanes. Instead of wasting all that thrust, it is used to turn another set of turbine blades mounted right behind the turbine blades in the jet engine. These two turbines are not connected to each other with a shaft – they are completely independent of one another.
Think of it like two fans facing each other. If one fan is turned on, it causes the other fan to spin. For you car guys and gals out there, this is the same principle that is used in an automatic transmission torque converter.
The secondary turbine converts most of that thrust back into rotational power and is hooked up to a reduction gear box to reduce the speed down to a usable level – about 15,000 rpm for RC helicopters. The secondary turbine doesn’t spin as fast as the primary turbine in the jet engine. This reduces the amount of heat and wear in the reduction gear box.
The above picture shows a two stage MW54 Wren model jet helicopter engine. Notice the collar that is bolted onto the back of the jet engine. This is where the secondary turbine is located. Bolted onto the back of this collar is the jet exhaust diverter. Behind the diverter, you can see the gear reduction box. This is a 90 degree gear box that allows for the more conventional "vertical" engine shaft placement that is used on most RC helicopters to drive the main gear.
The picture below shows the individual components of the second stage.


[size=18]


This method of capturing the thrust to spin another turbine increases efficiently tremendously. A model helicopter two stage turbine engine is about 80% more efficient than a direct drive turbine engine.
By using up most of this thrust to spin another turbine, there is much less thrust force exiting the exhaust nozzle/s and the effects of jet exhaust pushing the heli around is greatly reduced.
The other big benefit is you are not loading down the engine as you would with the direct drive method. There is no mechanical connection between the engine and the gear box, this means a much smoother running model turbine engine, better engine management, better speed control, and reduced vibrations.
Of course there is a bit more weight with a two stage turbine and it is more costly. These are insignificant concerns next to the many advantages 2 stage turbines provide. If you are serious about turbine RC helicopters – the two stage turbine engine should be your only consideration.
[/size]
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:37 am

Is A Turbine RC Helicopter Right For You?

A Turbine RC helicopter is certainly a very realistic goal. Other than the complexities of the
turbine engine (which really is not that complicated), if you are mechanically inclined and have mastered nitro, gas, or even larger electric powered RC helicopters, a turbine RC heli can certainly be the next logical step.


Prices can get up there ($7,000 – $15,000 for helicopter and engine); but considering there are certainly more expensive hobbies such as snowmobiling, ATV’ing or even golfing for that matter, turbine RC helicopters are not unrealistic. With Bergen RC and Wren combining forces and introducing the new
Intrepid 44 Magnum for just over $5K, prices are still high, but continue to drop.
What I am getting at here is everything is relative. If you are passionate about RC helicopters; RC turbine helicopters will take you in a new and rewarding direction and cost the same or even less than many more popular hobbies and past times.

Turbine RC Helicopter Operating Costs & Upkeep


Speaking of cost, what about upkeep? Well considering the mechanics are pretty much the same as large gas and nitro helis, you can expect that same kind of mechanical component cost. Good quality turbine engines if properly cared for should run at least 50-70 hours between services – that is 300-420 ten minute flights – a lot of flying.
Turbines spin at very high speeds – upwards of 160,000 RPM. They have two special bearings (one at the front and one at the rear) that look just like regular ball bearings but are made of ceramic to handle the very fast rotational speeds coupled with the high amounts of heat they are subjected to. These bearings will be your main service items on the engine throughout the years.
The front bearing in the turbine is the one that takes most of the punishment and usually the first to go. Chris Bergen of
Bergen RC told me you can actually "hear" when these bearings start to go as they wear and loosen. These bearings will generally cost around $100 USD each and as I said are really the only true wear and tear parts in the engine.
So much has to do with how you treat your turbine engine, but RC helis are generally not running these little beasties at full power and this saves both bearings and fuel. For example, during a normal flight, my Wren MW-54 two stage heli engine is usually spinning not much more than 100,000 RPM, and I have my maximum RPM limit set to 130,000.
[url=http://syrianarmyfree.com//www.pinterest.com/pin/create/button/?url=http%3A%2F%2Fwww.rchelicopterfun.com%2Fturbine-rc-helicopter.html&media=http%3A%2F%2Fwww.rchelicopterfun.com%2Fimages%2FJet_Oil200pics.gif&guid=fv8upPSpeQBr-0&description=Is A Turbine RC Helicopter Right For You%3F]6[/url]

That said, even at lower power levels, turbines are still thirsty, generally consuming at least 100 ml of fuel per minute. They use regular kerosene or jet A1 fuel mixed with turbine jet oil. Even at that high consumption rate, fuel costs will be less than nitro fuel, a little more than gas however.






[url=http://syrianarmyfree.com//www.pinterest.com/pin/create/button/?url=http%3A%2F%2Fwww.rchelicopterfun.com%2Fturbine-rc-helicopter.html&media=http%3A%2F%2Fwww.rchelicopterfun.com%2Fimages%2FIsobutane_fill250pics.gif&guid=fv8upPSpeQBr-1&description=Is A Turbine RC Helicopter Right For You%3F]6[/url]

You also have to use small quantities of propane, butane, or a propane/isobutane mix (high performance camp fuel such as Coleman Powermax fuel for example) when starting the turbine (unless you have a "kerostart" system), but these costs are minimal.
[url=http://syrianarmyfree.com//www.pinterest.com/pin/create/button/?url=http%3A%2F%2Fwww.rchelicopterfun.com%2Fturbine-rc-helicopter.html&media=http%3A%2F%2Fwww.rchelicopterfun.com%2Fimages%2FFueling_Intrepid500pics.gif&guid=fv8upPSpeQBr-2&description=Is A Turbine RC Helicopter Right For You%3F]6[/url]

As you can see, refueling a turbine RC helicopter is very much the same procedure as a two stroke gas powered one and operating costs are similar. The Bergen Intrepid here takes about 1.2 liters of fuel per fill and that gives a good 10 minute flight with a couple minutes of reserve. Jet A fuel where I live is about a $1.70 a liter so that is certainly less costly per flight than a big thirsty 90 size nitro engine, but is more than gas (both in cost per L and consumption rates).
Also notice the CO2 fire extinguisher which is a MANDATORY safety item you need at all times with any turbine powered RC model in case of fire.

Dry chemical extinguishers like those found at the local hardware store are not recommended since the dry chem WILL damage the turbine engine. The picture to the right shows what happens when a dry chem extinguisher is used. The dry powder is sucked into the engine, melts inside the combustion chamber, and will usually at a minimum wreck the turbine and combustion chamber sections of the engine.
[url=http://syrianarmyfree.com//www.pinterest.com/pin/create/button/?url=http%3A%2F%2Fwww.rchelicopterfun.com%2Fturbine-rc-helicopter.html&media=http%3A%2F%2Fwww.rchelicopterfun.com%2Fimages%2FIntrepid_nosein500pics.gif&guid=fv8upPSpeQBr-3&description=Is A Turbine RC Helicopter Right For You%3F]6[/url]

So - operating costs are in the same ball park as large nitro or gas models – assuming you don’t crash regularly and have to replace turbine engines on a monthly basis (the engine is the single most expensive component on the bird usually making up for about 75% of the cost). If that is you, better hone your flying skills first. The last thing this hobby needs is for turbine powered model aircraft to get a bad image because of bad pilots.

There is one last point to consider when you are wondering if a turbine RC helicopter is for you. Perhaps you stumbled upon this site looking for RC turbine jet information or are thinking a turbine RC jet is a better choice.
I fly planes too and admit the thought of a 1/6 scale turbine powered F-16 screaming through the air at 200+ kph is a powerful image - but I would be too scared to fly it. With a turbine RC helicopter, I can keep it as close to the ground as I want or fly nice and slow scale type helicopter flying while getting a full dose of turbine noise and smell.
This goes right back to the point I made above about bad pilots. I know my flying skills are probably not good enough to fly a turbine jet, but I do know they are good enough to fly a turbine heli. You must also evaluate your own skill level (flying skills & technical skills) before deciding if you are ready for this next fun step.
The only way I could personally justify having this much money tied up in a RC aircraft is in knowing that there's minimal chance it will crash or crash hard enough to be a complete write-off. Seeing that I don't do any fancy aerobatics with my Intrepid turbine heli and have had many enjoyable flights with it so far, that is a very realistic outlook in my opinion.
Just remember however, crashing is part of this hobby, and you have to do a little sole searching within yourself knowing full well it is not a question of if it will crash, but rather when it will crash. Perhaps that fear is what will keep your turbine RC helicopter safe for many years to come.

This is not to say you can’t perform 3D aerobatics with certain turbine RC helicopters, but I know for a fact crashing is part of 3D – you can’t get away from it... sooner or later the ground always wins. On the other hand, if your skill and bank account allow it, you will impress people beyond measure as Chris demonstrates below flight testing his new Magnum 44 Turbine RC Helicopter.
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:38 am

MODEL TURBINE SAFETY

I have to talk a bit about RC model turbine safety. This goes without saying, but model jet engines introduce new dangers to the hobby.





It is said that RC helicopters are potentially the most dangerous of all RC vehicles. If that is the case, then RC turbine helicopters are the most dangerous of all RC helis. I would argue that RC turbine jet airplanes are more dangerous than helicopters simply because of the very high speeds they fly at.
In any case, I am not starting a debate which has higher risk factors. I also don’t want to imply that model turbine engines are small bombs waiting to explode – they just require a little more care and attention when using them.

Judgement Safety
I already talked about this in the is a RC turbine helicopter right for you section, but it is worth repeating. “If your knowledge about how turbines work and flying skills are not up to a certain level, please don’t even think of getting a turbine powered aircraft”.
Like I said before, turbine powered RC aircraft could cast a very negative image on our hobby if the care, attention, and respect they deserve are dismissed, forgotten, or ignored.
As the price of model turbines keeps getting lower, more and more people will be introduced to turbine powered flight. This is great - provided we all understand that the media loves to blow things out of proportion, and only a few RC turbine related incidents could have our hobby backed into a corner.

Failsafe Turbine Settings
Failsafe is a term that describes a preset condition of operation if your RC model ever looses or gets corrupted radio signals. For those of you with PCM or DSM radios, this term is already familiar too you.
For example, if you are flying your RC turbine helicopter or airplane and get interference or a loss of radio signal, the FADEC engine computer will first ride out the interference or signal loss for 0.5 seconds and maintain engine speed. If the radio signal is still corrupted or lost after 0.5 seconds the FADEC will set the engine speed to idle.
The idle speed setting is then maintained for 1.5 seconds and if the radio signal is still lost or corrupted after this 1.5 second idle command (2 seconds in total from the initial signal loss), the FADEC will then shut the engine down by turning off the fuel pump. If the radio signal returns any time during this 2 second period, the FADEC will reset the timer and return to normal function.
The times are programmed into the FADEC computer and cannot be changed. These model turbine safety guidelines have been determined by several model aviation governmental departments world wide.
The FADEC failsafe systems works with PPM, PCM, and DSM radio systems.
One very important safety point to mention if you are using a PCM or DSM radio - Always program your failsafe to shut the engine off, never fly a turbine RC aircraft with your failsafe on your radio set to hold. If you do and you have a signal loss, the FADEC won’t see this because your receiver has filtered it out and the turbine will continue to run at that hold setting.

Fire Safety
Unlike nitro engines or gas engines, model jet engines have a much higher chance of catching your plane, helicopter, or surroundings on fire. This is because of the high heat and the fact that the turbine has a steady flame burning inside the combustion chamber.
The most dangerous time for a potential fire is at engine start up. ECU’s have greatly reduced the risk, but if there is raw jet fuel in the combustion chamber for what ever reason, it can cause a large flame or serious fire when the turbine ignites.
My first experience with this was while starting my bird in the early spring when the grass was still dry and brown. I overfilled the isobutane starting gas bottle and a good 1 foot long flame shot out both exhaust nozzles when the turbine "popped" to life. Normally this isn't an issue and it looks pretty neat when it happens. Unfortunately, because the grass was dry, it caught on fire behind both exhaust outlets and I had to act pretty fast to get the heli out of of harms way. Lesson learned, start your bird over a non combustible surface if possible.
Always have a good quality, 5 lb or more, CO2 fire extinguisher on hand - it is a MANDITORY requirement for all RC turbine powered models. It has to be a CO2 type extinguisher since dry chemical extinguishers will damage the turbine engine. Hopefully you will never have to use it, but it is safe insurance should anything go wrong.

Like everything else, model turbine safety starts with basic common sense. Safety and fun really do go hand in hand.


البحوث السابقة من الموقع التالي :

http://www.rchelicopterfun.com/rc-tu...elicopter.html
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    الأحد يونيو 08, 2014 2:39 am

UNDERSTANDING THE NITRO RC HELICOPTER








Nitro RC helicopters, also known as "Glow Powered" RC helicopters are still popular and serious contenders with electric RC helis. Why?

Because they are tough and can take a beating, they give good power to weight ratios, they are the lowest cost option for a fuel powered bird, and they have proven themselves time and time again. The pros and cons of nitro RC helis are explained on the Best RC Helicopter Power page.
The simple fact is without the model nitro engine (also called a glow engine), it is doubtful that RC airplanes and helicopters would have taken off – literally.
These little engines produce so much power for their size and weight, it's little surprise that nitro RC helicopters are still the number one choice for so many people.

If you are familiar with large electric RC helicopters, the basic layout and components in a Nitro heli are really not much different. The main component differences mostly revolve around the engine :-)
These include the engine itself, starting shaft, centrifugal clutch, a cooling fan and shroud, the muffler/tuned exhaust, the fuel tank, fuel tubing, an extra servo to control the carburetor, and perhaps a governor to govern engine speed (the carburetor/throttle servo is controlled by the governor). There might also be an on board glow driver if an external glow driver is not used.

Let’s first clear something up when it comes to nitro RC helicopters, more specifically nitro engines in general.
Many people confuse or call these gas RC helicopters – this is not correct.
Gas RC helicopters use 2 cycle gasoline engines, similar to the ones used in small gas powered chain saws or gas leaf blowers.
Nitro engines or glow engines are completely different. They use special fuel consisting of (methanol, nitro methane, and oil) and as the name "glow" suggests, they don’t use a spark plug - a glow plug is used. Lastly, nitro/glow engines run at much higher RPM's – usually in the 13,000 – 16,000 RPM range.
In order to build and fly a nitro RC helicopter, you have to be very familiar with how nitro engines work. The following items are some basic terms & items you'll need to understand when operating a glow engine.



  • Nitro Fuel (percentage of nitro methane)
  • Glow Plugs (heat ranges)
  • Mufflers & Exhaust Systems (pressurized & tuned pipes)
  • Differences Between Ringed & ABC Nitro Engine design
  • Nitro Engine Break In Procedures (heat cycling)
  • Nitro Tuning (low, mid, and high needle/mixture settings)
  • Nitro Engine Care (after run oil, cleaning, inspecting, etc)

Four Stroke Nitro RC Helicopter Engines



Most people will only use 2 stroke nitro engines in their helicopter because of the impressive power to weight ratio. There are still a few 4 stroke nitro engines out there so you should at least know a bit about them.
The 4 stroke heli nitro engine has been around for about 35 years now. They run at a lower RPM and thus produce less noise. It looked like these would become popular for R/C helicopter use back in the day; but the added weight, extra cost, and reduced power has kept them pretty much under the radar, and now a days you hardly ever see one. OS discontinued their 4 stroke heli engine lineup a number of years back and there is no reason to think they will ever return.
There is nothing wrong with the 4-stroke nitro engine, the 2-stroke simply produces more power and doesn’t cost as much making it the preferred and more robust choice with less moving parts inside.

Unique Nitro Engine Requirements
Now that you know a bit about nitro engines, let’s examine how they apply to nitro helicopters. But before getting into that boring stuff, here's a video of a nitro powered T-Rex 700N DFC in action...




The RC helicopter relies on its engine more than any other form of RC model. RC planes can glide in for a landing, RC cars and trucks simply coast to a stop and RC boats will continue to float if their engines quit. Helicopters on the other hand depend on engine power to stay in the air.
Yes there are auto rotations, but when you are learning, an engine flame out will pretty much ruin your day and lighten you wallet.
This dependence on reliable power is key to understanding the unique ways nitro engine set-ups in RC helicopters differ from any other RC model.
There are other challenges that nitro engines in RC helicopters face such as getting adequate cooling and the many different ways of starting the nitro engine.
What about the nitro fuel tank ? Simple right... This is a huge topic on its own, getting it wrong ensures helicopter flying and engine problems. Speaking of fuel, what about all that messy oil residue.

When Starting A Nitro RC Helicopter. The blades won't spool up until the engine speeds up and the centrifugal clutch engages.






"How does the Clutch Work?"
I get this question often enough I thought I better address it.



Here is typical centrifugal RC helicopter clutch with the starter shaft attached to it. The clutch is attached to the rotating face of the cooling fan which is attached to the nitro or gas engine output shaft. In other words, whenever the engine is spinning, the clutch is also spinning. As the engine speeds up, centrifugal force cause the ears of the clutch (circled in red) to spread outward.



The centrifugal clutch is rotating inside the clutch bell seen here. When the ears of the clutch spread out as engine speed increases, they start rubbing on the clutch liner circling the inside of the clutch bell, and the clutch bell slowly starts rotating along with the clutch. Once up to enough speed, the ears on the clutch are spread out with such a large amount of centrifugal force, the clutch and clutch bell are more or less locked together and rotating as one unit. The clutch bell has the pinion gear on the top of it and that is what in turn spins the main gear on the rotor shaft.

It is therefore very important to always start a nitro RC helicoper with the throttle stick in the idle position so the engine doesn't start at a fast speed. If it starts at speed, the clutch will engauge almost the instant the engine fires up, causing you some exciting moments as you go fumbling for the radio with one hand while holding the rotor head with great force to keep it from spooling up in your other hand. While all this is happening, the clutch ears are burning and polishing the liner inside the clutch bell... Nothing quite like the smell of burnt nitro RC Helicopter clutch on top of all the other drama going on - yummy ;-)
The photo below shows how the clutch assembly, engine, gears, and starter hub are positioned. Normally you don't see much of this from the clutch bell downward, but I have removed the cooling fan shrouding for this photo.

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:07 pm




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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:07 pm

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:08 pm




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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:08 pm




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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:08 pm

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:09 pm

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:09 pm

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:09 pm

جهاز ليزر لتحديد المسافات بدقة عالية وبسهولة يمكن استعماله لتحديد بعد الدبابة فيمكن استهدافها عن طريق مدفع هاون

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:10 pm

د


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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:10 pm





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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:11 pm

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:11 pm

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:11 pm

اصنع طيارة تعمل بجهاز تحكّم عن بعد

ملف word

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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:11 pm

موقع يمكن الاستفادة منه
http://www.cnchelicopter.com/servlet/StoreFront
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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:12 pm










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مُساهمةموضوع: رد: موسوعة صناعة الأسلحة    السبت يونيو 21, 2014 8:12 pm







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