carey shurley
03-25-2011, 04:21 PM
I've often gotten questions about whether or not a generator should be installed on a gas helicopter. Sometimes the question is almost presented as an assumption that the model won't fly without it.
So lets talk about on board generators. First off, I'm not going to spend time here explaining how they technically work. This is more focused on whether or not you should have one.
one of the unique things about gas powered helicopters is that depending upon how big of a tank you've installed, they could fly for 30 minutes or longer on a single tank. Thats 2-3 times longer than most glow models and 4-5 times longer than high performance electrics.
if you're at a field with other pilots, fixed or rotory wing this is not going to endear you to other pilots cause you're potentially hogging up airspace. But if you have easy access to your airspace you could easily fly for hours on very little fuel
obviously the battery that powers the onboard electronics may well have a problem with enough capacity to support such long flight times.
so there are 4 solutions to that part of the problem
use high capacity batteries
bring additional charged batteries that you swap out
recharge between flights
install an onboard generator to constantly charge the batteries
to help you determine if this makes sense or not, I offer this:
first question - how much time do you fly in a session? (and this is really a key question)
if you're the type of person who makes 1-2 flights when you go out to the field and no more, then your onboard battery packs will be just fine without any additional gadgets, especially if you're using Lithium based batteries. Depending on the capacity they could run for 2-3 hours or more without re-charging. For most people thats a lot of flying time. now granted you've got to re-charge before your next outing.
If you are just a casual flyer, then a generator would be more of something that you want than something you really need. In that case the rest of these questions won't really matter. On the other hand if you make many flights over several hours in total..........then you may want to generate.
second question - when you're out flying do you just pound the flights one after another or do you make a flight and then visit with your friends for some period of time between flights?
Most hobby pilots I know talk as much as they fly. Which means you've got time to recharge between flights. If you recharge after every flight it won't take long to do, 30-45 minutes tops. Yes I realize this involves bringing chargers and a power supply. These days most of the flying fields I've visited are full of chargers and 110 generators because you've probably got something electric that you're gonna also fly. At any rate If the idea of charging between flights repulses you..........then you may want to generate.
an alternative is to have one or more extra flight batteries that you charge and bring with you. In this setup you fly until your initial battery gets low and then just swap it out. usually takes less than 5 minutes and you'll be limited in total flying time to the number of batteries you have. And consider how many extra batteries you can buy for what a generator setup costs. Now if you see this is just wasting money on extra batteries.......... then you may want to generate.
third question - do you have an electronic ignition??
a couple of the engines available use electronic ignitions out of the box and they can be adapted to most any motor. They require a power supply, typically 4.8-6 volts to operate. Most people use a separate battery pack to power the EI system although its technically possible to run all the electronics from a single power source.
The issue is, if the power source for the EI gets low the motor will not run properly or may stop running altogether. The EI on the Zenoah G20 is quite hungry and consumes a lot of power. Other systems are less hungry but still draw power. So not only is your total flight time limited by the power available for the onboard electronics but for the ignition system as well. If you have an EI system on your motor..........then you might want to generate.
fourth question - do you crash a lot?
the current generator systems for helicopters are not complicated, they use an electric motor that connects either to the start shaft, tail drive gears, or some other engine speed (or near engine speed) rotating component and some circuitry.
Depending on what model you have and how the generator mfgr has mounted it, the generator components may or may not be exposed in a crash. Obviously if you crash you're gonna tear up more than any generator parts but consider that it is possible that you may break one of the generator components which will need to be replaced and will have some cost. If you rarely crash..........then you might want to generate.
After answering these questions, you'll have a better basis to decide if you should generate or not
Regardles there are some other attributes about on-board generators that you might want to consider.
You've still got to have an onboard battery otherwise if for any reason the generator fails to make power, sayonara to your model.
Having said that though for the most part, you don't have to worry about what the onboard voltage is (have you started to wear down the batteries). Unless the onboard battery or generating system has shorted or has some other catastrophic internal failure as long as the motor is running, so will your electronics.
Even with a generator you should make sure that the onboard battery is fully charged or nearly fully charged before you start flying. The purpose built generators will charge the battery but they will be working harder to do so. If you fly often enough that your battery won't self discharge then this is a non-issue as the generator will keep it topped off.
you can use lower capacity and therefore lighter batteries. As long as the generator is functioning and the motor is running, you've got all the power you need to run the onboard electronics. However the tradeoff is that whatever weight you save in batteries you'll lose in the weight of the generator components.
even with a generator it does not result in a "don't care" attitude in regards to the onboard battery. The generator system can fail, the battery can short, something can become unplugged. Just like with your car its still possible to lose power if you don't preflight properly. Safety still has to be a key concern.
The bottom line:
should you install a generator on your gas helicopter?
Its certainly not a requirement, I use Li-Ion batteries and can fly for longer than I want on a single charge. With a spare battery I could fly most of a day at the field. If your motor uses an EI system, you'll get more flying time.
Depending on your flying characteristics it can simplify your flying and what equipment you need to bring to the field with you. But they are not free either, they cost as much as several batteries or a very good charger
If you're careless about checking your battery voltage..........then you might want to generate. It could save your model
So lets talk about on board generators. First off, I'm not going to spend time here explaining how they technically work. This is more focused on whether or not you should have one.
one of the unique things about gas powered helicopters is that depending upon how big of a tank you've installed, they could fly for 30 minutes or longer on a single tank. Thats 2-3 times longer than most glow models and 4-5 times longer than high performance electrics.
if you're at a field with other pilots, fixed or rotory wing this is not going to endear you to other pilots cause you're potentially hogging up airspace. But if you have easy access to your airspace you could easily fly for hours on very little fuel
obviously the battery that powers the onboard electronics may well have a problem with enough capacity to support such long flight times.
so there are 4 solutions to that part of the problem
use high capacity batteries
bring additional charged batteries that you swap out
recharge between flights
install an onboard generator to constantly charge the batteries
to help you determine if this makes sense or not, I offer this:
first question - how much time do you fly in a session? (and this is really a key question)
if you're the type of person who makes 1-2 flights when you go out to the field and no more, then your onboard battery packs will be just fine without any additional gadgets, especially if you're using Lithium based batteries. Depending on the capacity they could run for 2-3 hours or more without re-charging. For most people thats a lot of flying time. now granted you've got to re-charge before your next outing.
If you are just a casual flyer, then a generator would be more of something that you want than something you really need. In that case the rest of these questions won't really matter. On the other hand if you make many flights over several hours in total..........then you may want to generate.
second question - when you're out flying do you just pound the flights one after another or do you make a flight and then visit with your friends for some period of time between flights?
Most hobby pilots I know talk as much as they fly. Which means you've got time to recharge between flights. If you recharge after every flight it won't take long to do, 30-45 minutes tops. Yes I realize this involves bringing chargers and a power supply. These days most of the flying fields I've visited are full of chargers and 110 generators because you've probably got something electric that you're gonna also fly. At any rate If the idea of charging between flights repulses you..........then you may want to generate.
an alternative is to have one or more extra flight batteries that you charge and bring with you. In this setup you fly until your initial battery gets low and then just swap it out. usually takes less than 5 minutes and you'll be limited in total flying time to the number of batteries you have. And consider how many extra batteries you can buy for what a generator setup costs. Now if you see this is just wasting money on extra batteries.......... then you may want to generate.
third question - do you have an electronic ignition??
a couple of the engines available use electronic ignitions out of the box and they can be adapted to most any motor. They require a power supply, typically 4.8-6 volts to operate. Most people use a separate battery pack to power the EI system although its technically possible to run all the electronics from a single power source.
The issue is, if the power source for the EI gets low the motor will not run properly or may stop running altogether. The EI on the Zenoah G20 is quite hungry and consumes a lot of power. Other systems are less hungry but still draw power. So not only is your total flight time limited by the power available for the onboard electronics but for the ignition system as well. If you have an EI system on your motor..........then you might want to generate.
fourth question - do you crash a lot?
the current generator systems for helicopters are not complicated, they use an electric motor that connects either to the start shaft, tail drive gears, or some other engine speed (or near engine speed) rotating component and some circuitry.
Depending on what model you have and how the generator mfgr has mounted it, the generator components may or may not be exposed in a crash. Obviously if you crash you're gonna tear up more than any generator parts but consider that it is possible that you may break one of the generator components which will need to be replaced and will have some cost. If you rarely crash..........then you might want to generate.
After answering these questions, you'll have a better basis to decide if you should generate or not
Regardles there are some other attributes about on-board generators that you might want to consider.
You've still got to have an onboard battery otherwise if for any reason the generator fails to make power, sayonara to your model.
Having said that though for the most part, you don't have to worry about what the onboard voltage is (have you started to wear down the batteries). Unless the onboard battery or generating system has shorted or has some other catastrophic internal failure as long as the motor is running, so will your electronics.
Even with a generator you should make sure that the onboard battery is fully charged or nearly fully charged before you start flying. The purpose built generators will charge the battery but they will be working harder to do so. If you fly often enough that your battery won't self discharge then this is a non-issue as the generator will keep it topped off.
you can use lower capacity and therefore lighter batteries. As long as the generator is functioning and the motor is running, you've got all the power you need to run the onboard electronics. However the tradeoff is that whatever weight you save in batteries you'll lose in the weight of the generator components.
even with a generator it does not result in a "don't care" attitude in regards to the onboard battery. The generator system can fail, the battery can short, something can become unplugged. Just like with your car its still possible to lose power if you don't preflight properly. Safety still has to be a key concern.
The bottom line:
should you install a generator on your gas helicopter?
Its certainly not a requirement, I use Li-Ion batteries and can fly for longer than I want on a single charge. With a spare battery I could fly most of a day at the field. If your motor uses an EI system, you'll get more flying time.
Depending on your flying characteristics it can simplify your flying and what equipment you need to bring to the field with you. But they are not free either, they cost as much as several batteries or a very good charger
If you're careless about checking your battery voltage..........then you might want to generate. It could save your model