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HomeAircraftHelicopterHelicopter Main Discussion › If Nitro is done...
01-21-2015 04:19 AM  3 years agoPost 61
turboomni

rrProfessor

East of the Equator

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YS has aslo had EFI for quite a while. They even have direct injection EFI. And even direct injected EFI with CDI. These are all marketed at the F3A pattern crowd.
Just curious does this system monitor either head temp ,,exhaust temp or analyze O2 in the exhaust? Does the system care what has happened after the combustion has happened in any way or care? How about a knock sensor? Air fuel ratio sensor? Temp sensor either on the head or exhaust as I said before. The biggest power from any IC engine that I know of are fueled by Methanol and nitro as in dragsters etc. Yet with the very small heli engine that is expected to produce amazing power there is no real engine management [other than feed the fuel what it thinks it should be fed] to make it better.Do you think a dragster has no monitoring of the engine before and after the boom in a cylinder?? I think there is alot of room for improvement.

Setup is everything, All my heli's can fly far better than I can pilot them

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01-21-2015 05:45 AM  3 years agoPost 62
Aaron29

rrProfessor

USA

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It does appear to have a throttle position sensor and crank sensor. But I doubt it has a MAF sensor or CHT/EGO2 sensors.

Course all that would come at a price that few would bite.

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01-21-2015 02:18 PM  3 years agoPost 63
turboomni

rrProfessor

East of the Equator

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The carb smart wasn't expensive but was rather crude. Does any one remember the carb smart? It used a servo to control the high speed needle valve that would respond to the computer which was monitoring the the head temp during flight. The user had the option for a target heat range. It worked well.

Setup is everything, All my heli's can fly far better than I can pilot them

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01-21-2015 02:45 PM  3 years agoPost 64
JasonJ

rrKey Veteran

North Idaho

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I remember the carb smart. I even thought of getting one but I never did. Seemed like a good idea. I think one concern was if there was a failure of some sort causing an over lean situation. I know proper setup had the servo operating the needle in a safe range but if a person didn't do their setup right it could be a disaster. I think people didn't want to fuss with it. At this point the idea is unlikely to be revisited since it's all about the electrons these days.

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01-21-2015 03:11 PM  3 years agoPost 65
jschenck

rrProfessor

La Vista, NE.

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Problem with EFI is
1. Weight - we demand light engines and a nitro/alcohol carb is light.
2. Cost - Personally I will not spend twice on the engine for EFI

I can't see how you could put any kind of reasonable exhaust sensor except perhaps temp since it's mostly going to be a spray of oil.

Carb smart makes sense to me. Be nice if we could bring back that concept with a more robust sensor, perhaps designed into the engine (e.g. a pocket in the cyl head just for a temp sensor)

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01-21-2015 03:21 PM  3 years agoPost 66
rexxigpilot

rrProfessor

Florida

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Don't you think that nitros are horribly inefficient? You set the needles so when loaded it wont burn up but anything less than that it's chugging fuel back for no good reason.
Yes, they are very inefficient. But it is not mainly because of the carburetor jet valves. It's because of the use of ports instead of proper valves and the inefficient nature of internal combustion engines (ICE).

Ports have too much overlap. As a result, much of the air-fuel charge is pumped straight out the exhaust port.

Even the most efficient ICE is perhaps only around 30% efficient. ICEs are like incandescent light bulbs. Most of their fuel's energy is converted into heat. The heat energy is pumped out the exhaust and lost.

A carburetor regulates how much fuel and air is used. Sure, the RC engine's carb is a simple device, but it's not wide open all the time. The barrel along with crankcase vacuum regulate how much air-fuel is delivered to the combustion chamber.

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01-21-2015 05:23 PM  3 years agoPost 67
rexxigpilot

rrProfessor

Florida

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I have a fuel injected OS FS-91SII-FI in my P51. Cost was the reason it didn't sell well. It cost $800 when I bought it for a huge discount. A similar OS 91 four stroke w/o fuel injection cost less than half that. However, my FI engine runs better than any RC engine I've ever seen. You can even adjust the fuel mixture while flying. These FI RC engines are still relatively simple devices. They regulate the amount of fuel delivered based on cylinder head temperature and RPM. I'm fairly sure a PID control is used.

The Carb Smart and other governors with mixture control like the MultiGov Pro have the ability to adjust the fuel based on cylinder temp only. They use a servo to adjust the main needle valve using feedback from a temp. sensor that has to be glued to the cylinder head. It works to some degree. However, they are too slow to respond and too crude in carb adjustment to work great. Because of the inherent hysteresis in this type of system, they need to utilize PID logic control. Not sure if any do.

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01-21-2015 07:12 PM  3 years agoPost 68
Rob43

rrKey Veteran

Midland, MI USA

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Yeah...and I can slowly scratch my fingernails down the full length of a blackboard too. LOL
Oh yeah...you're the one that planned to run 2600 rotor speed on your 700 nitro, if I am not mistaken..
Its still a lot easier to get long flight times on wet power by just adding a larger tank. I'd like to see an electric that can match the 20-30 minute flight times of a 700 gasser
1. I've not seen any aftermarket fuel tanks for increasing on-board capacity. Evidently, there's no market for it. I believe it's because the 7-10 minute range is enough for most nitro pilots. It is for me, at least.

2. If you're flying at a club flying site, 30 mins isn't very considerate to others who might want to fly, not to mention the kind of noise they make. I can't bear to listen to a gasser for long. Different frequency and tone is just not pleasant to me.

Rob

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01-21-2015 07:13 PM  3 years agoPost 69
turboomni

rrProfessor

East of the Equator

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Yes as I said the Carb Smart is crude. But I remember when using it how over rich I had been without the carb smart to be safe. I had the Hyper 50 at the setting most were using at the time, 1 1/4 on the high comes to mind. My Raptor 50 went from 6 to 7 minutes to over ten minutes on 30%. I never burnt out the engine or plugs. When flew hard [at least for me] lots of smoke as before but with light loading there would be less smoke and in hovering. Hit it and very quickly the smoke would come gushing out again. There was more power to boot and transitions were very smooth and quick.

As jschenck said
Carb smart makes sense to me. Be nice if we could bring back that concept with a more robust sensor, perhaps designed into the engine (e.g. a pocket in the cyl head just for a temp sensor)
I agree with this as a way to make the system even quicker with out the complexity of exhaust analyzing systems.
Also if I remember correctly in the event of a sensor failure the computer will go rich and stay there.

Setup is everything, All my heli's can fly far better than I can pilot them

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01-21-2015 11:57 PM  3 years agoPost 70
jharkin

rrApprentice

Holliston, MA - USA

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Alright, let me try and take these in order...
before the E guys bust that 1.
I can run at the same power level as gas by lowering my head speed
and using 2 6s5000 in parallel
Let me guess. Your 700 electric is probably running some crazy speed like 2400+ at 12-14 degrees pitch, right? and getting 3-5 minutes. I’ve seen those low headspeed videos, wire the batts in parallel rather than series and you trade head speed for runtime.
So now instead of 2400 for 4 min, you are running 1200 rpm for 8-10 minutes.

So you got more time, but equal power and time as a nitro or gasser? I dont think so. Is it really as powerful as a nitro at 1200rpm? or even a gasser? Unless its pulling ridiculous pitch I have doubts.
My latest 700 gasser is running a tuned Zenoah 30cc and I'm pulling 12.5 deg collective on 716 blades at 1900 rpm and I can do a full collective punch out with zero bog. And with the 22oz TRex tank it can keep doing that for 25-30min (well maybe only 15 if I was smacking it full throttle like that). So long that I get bored before the tank runs out.

Can a 12s 700 running half speed on 6s match that? I’m happy to be proven wrong but I doubt it.

I’m not saying a 700 electric wont embarrass the gasser for brute power. We all know it will. But the numbers don’t lie - electrics have crazy power density, but the massive energy density advantage of methanol and gasoline is just too much to overcome for duration right now, even factoring in the low efficiency of internal combustion. Someday there might be a breakthrough to bring batteries closer but right now, IC still wins. Which is why we are a long way off from a battery powered plane you can ride in.

-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks

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01-21-2015 11:57 PM  3 years agoPost 71
jharkin

rrApprentice

Holliston, MA - USA

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Do you think a dragster has no monitoring of the engine before and after the boom in a cylinder?? I think there is alot of room for improvement.
Actually in a lot of race series they don’t, due to rule restrictions. Much drag racing and NASCAR are only allowed to use carburetors. Formula One allows FI and complex engine management but that series has become more aobut tech than driver skill.

Somebody upthread said that carburetors only exist in lawn mowers now, but I think you guys would be surprised how much low tech is still out there. Its not just lawn tools - A lot of motorcycles are still carbureted, as are many light civil aircraft. In fact you might be shocked to know that if you drive to you local civil airport and hop in a rental Cessna or Piper, not only is it carbureted, but it has magneto ignition, a cast iron block and pushrods.

The reason is the same logic that had the Space Shuttle flying with 1970s computers. Carbs & mags are simple and fool proof and do a good enough job with much lower risk of failure in the constant power use on a light airplane. There wasn’t enough performance or efficiency reason to make FI and EI wrth the added cost.

This is the same reason that the occasional appearance of FI for model engines never really takes on (and its been done over and over and over)… for our usage the average modeler doesnt see a need to spend hundreds more up front to save a couple bucks in fuel.

-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks

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01-21-2015 11:58 PM  3 years agoPost 72
jharkin

rrApprentice

Holliston, MA - USA

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Yes, they are very inefficient. But it is not mainly because of the carburetor jet valves. It's because of the use of ports instead of proper valves and the inefficient nature of internal combustion engines (ICE).
Ports have too much overlap. As a result, much of the air-fuel charge is pumped straight out the exhaust port.
Even the most efficient ICE is perhaps only around 30% efficient. ICEs are like incandescent light bulbs. Most of their fuel's energy is converted into heat. The heat energy is pumped out the exhaust and lost.
Not quite. Two stroke engines MUST have port overlap by design. This is how it scavenges exaust from the cylinder on the same cycle as the intake, using the incoming charge to push out the old. In a four stroke you don’t have the losses of raw fuel out the exhaust and you gain efficiency, but you offset that by losing half you power strokes. So you have to go up in displacement, and hence weight to get the same power. And in a single cylinder you also have a big increase in vibrations. Both of these factors we can deal with fairly easily on a plank but they have killed off every attempt to do it on a model heli.

(now the same is not exactly true on full scale aircraft and cars as engineers can use lots of tricks to bring4S near to parity with 2S like forced induction, variable valve timing, and so on – but none of these are practical at our scale)

In terms of thermal efficiency – you average gasoline 2 stroke is around 20-25%, four stroke is in the high 20s, very efficient 4 strokes in automobiles like an Atkinson cycle might get into the high 30s and diesels can approach 40%.

Nitro engines have similar thermal efficiencies, but their fuel efficiency is worse because methanol only contains about 2/3 as much energy per gallon as gas. They also burn at a much richer air fuel mixture further exaggerating the difference in fuel consumption (and this is how a nitro engine can make more power than gas even though the fuel has less energy).

-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks

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01-21-2015 11:59 PM  3 years agoPost 73
jharkin

rrApprentice

Holliston, MA - USA

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1. I've not seen any aftermarket fuel tanks for increasing on-board capacity. Evidently, there's no market for it. I believe it's because the 7-10 minute range is enough for most nitro pilots. It is for me, at least.
2. If you're flying at a club flying site, 30 mins isn't very considerate to others who might want to fly, not to mention the kind of noise they make. I can't bear to listen to a gasser for long. Different frequency and tone is just not pleasant to me.
Yeah I doubt there would be any marketed add on tanks as most sport and 3D pilots wouldn’t have interest… but its certainly not hard to rig up. I’ve seen large scale UAV setups – like 700-800 gassers rigged with saddle tanks for hour long aerial video flights. Not hard to do with gas but times like that are pretty much physically impossible with electric.

7-10min probably average in the hobby is because that’s what heli pilots have always been used to. For me I came from nitro and gas planks that we typically would run 15 minute tanks so 10 seems short and a 5 min electric is just intolerable to me. Everyone’s preference is unique and I don’t begrudge anyone their choice. I fly all 3 power sources myself (E, N, G)

I’m not saying that I fly 30 min, just that my heli is capable of it. Honestly I’d have been happy if the designer had put a smaller tank in it, as is I usually just land with 1/3 left or so. At my field if there are guys waiting our rule is 10-15min top and I follow it. If I'm out alone I’ll go a bit longer.

Funny you mention the noise of gas. That’s another preference thing… I find the 12000rpm gas done more pleasant than a 16000 rpm nitro myself. To each there own.

-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks

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01-22-2015 12:18 AM  3 years agoPost 74
turboomni

rrProfessor

East of the Equator

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Let me guess. Your 700 electric is probably running some crazy speed like 2400+ at 12-14 degrees pitch, right? and getting 3-5 minutes. I’ve seen those low headspeed videos, wire the batts in parallel rather than series and you trade head speed for runtime.
So now instead of 2400 for 4 min, you are running 1200 rpm for 8-10 minutes.

So you got more time, but equal power and time as a nitro or gasser? I dont think so.
I fly gassers and now also am experimenting in LHS electric 700E.
I run one 6 cell pack so it is much lighter than a 12 cell heli.
Head speed is 1400 or so. Is it comparable to a nitro? No. Is it comparable to a gasser? I would say yes. It is more powerful than my old 1005 Min Air with a Hanson 26cc and it is abit less powerful than my Spectra FBL with a 29cc Hanson. The 700E though flys effortlessly with its much lower disc loading. I bring it in at 10 minutes to be safe on the lipos as compared to 15 or more on my Spectra or 1005.It does not compare well to the screaming gas Goblins running high engine and head speeds however.

By the way jharkin lots to great info in your last few posts and I stand corrected about the dragsters.

Setup is everything, All my heli's can fly far better than I can pilot them

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01-22-2015 02:21 AM  3 years agoPost 75
Rob43

rrKey Veteran

Midland, MI USA

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Right. It's just a hobby too. Easy to get carried away. It's all for fun, and not right or wrong. My favorite is what I am flying at the moment...

Rob

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01-22-2015 03:44 AM  3 years agoPost 76
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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How would a carb smart work with a 3 needle carb ?

I think it's a wonderful idea for those of us that have tuning deficit syndrome

spending time, paying attention

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01-22-2015 03:54 AM  3 years agoPost 77
Aaron29

rrProfessor

USA

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Most engines have a "main" needle that can control overall flow while the other two are for fine tuning different spots across the range.

With OS the main is usually the high. With YS, it's typically the "hover" needle, which I think of as midrange.

So with an OS, you set the high first, and then tune the mid and idle. If you enrich the high needle, the mid and low are automatically enriched.

YS, at least the two I've owned, is weird. You set the hover needle first. Then the high and low. If you move the hover needle, it will affect the high and low.

So in short, you'd only put the carbsmart on the one "main" needle.

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01-22-2015 04:18 AM  3 years agoPost 78
turboomni

rrProfessor

East of the Equator

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How would a carb smart work with a 3 needle carb ?
I have no feaken idea as I have been out of nitro for a long time and never dealt with a 3 needle carb. Seems to me a 3 needle carb is there for experienced flyiers to really dial it in. A 2 needle carb I would guess would be easier to dial in with carb smart type system as it just regulates the big hose or high needle valve to work. But really I do not know.
I think it's a wonderful idea for those of us that have tuning deficit syndrome
Well I read all the forums when flying nitro and my needle valve settings were on the safe side and had no problems without the carb smart. But I was really woken up with it. It took awhile to dial it in but the directions were very intuitive. I would think anyone could dial it in just like anything else in this hobby.

I have left nitro long ago but I always knew it was very inefficient in every way and always thought it could be improved with very few mods to react to the performance in a closed loop ,, even if primitive,,even a simple as head temp to make it more efficient. Why is there not an improved version of the carb smart available today? In my opinion your bigger nitro engines they may make more power but are even more inefficient than the smaller displacement engines because ther is absolutely no communication between the carb and the engine operation,,heat ,,or o2 or what ever. I would think an original carb smart today would be better than you all have now ,,which is nothing.

Setup is everything, All my heli's can fly far better than I can pilot them

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01-22-2015 04:45 AM  3 years agoPost 79
EEngineer

rrProfessor

TX

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Even though 2-cycle engines are "inefficient"....their performance can be enhanced by a "tuned pipe" exhaust.....which "reflects" the wasted fuel exhausted from the exhaust phase....and "supercharges" it back into "intake" before the port closes.

4-cycles can't do that.

And, with a 2-cycle, head shims/nitro content/with lotta oil can increase performance too....

And, they're easier to re-build...

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01-22-2015 05:03 AM  3 years agoPost 80
turboomni

rrProfessor

East of the Equator

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I agree engineer ,,I remember tuned pipes on my aircraft from the 1980's that really woke up performance. They really did suck the fuel then too!! Gasser heli's have been doing this for sometime now too. I do remember raising and lowering the head for less or more nitro too. I remembered really looking into 0 or very low nitro fuel and having to remove the head shims that were required for high nitro content fuels. I just think nitro fueled heli's could be more efficient and have more power as a result too very easily. Much more research has been put on electric heli's in recent years and the only real developments on nitros is bigger displacement.
My opinion only!

Setup is everything, All my heli's can fly far better than I can pilot them

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