In-Flight Mixture Control
11-11-2008, 10:41 PM
#26
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RE: In-Flight Mixture Control
hAS ANYONE TRIED THE cARBsAMART BY csm ON AN AIRPLANE? It is designed for rc heli's. It has a temp sensor on the head and a mini servo for the main needle valve hooked to a small computer. You set the desired head temp [for my 50 sized heli it is set at 110C] and it does the rest . It only uses the RX for power and is not controlled by the radio'.
11-11-2008, 11:36 PM
#27
Senior Member
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RE: In-Flight Mixture Control
I just bought a Carb Smart for my Raptor 30, but I have yet to get into the instructions.
The heli with collective pitch keeps the engine spinning within a very narrow rpm range. Throttle is applied to the engine when the load increases on the engine. This was not done by metering after measuring any engine parameter in real time, before the Carb Smart came along. It was a preset set of throws which had to be adjusted by trial and error after the heli landed.
However, an airplane engine is not focused upon a very narrow rpm band, as the helicopter is focused, so it isn't likely that a heli tuned Smart Carb device will be all that useful unless collective pitch is used on the airplane, which has been done before, long, long ago.
Ed Cregger
The heli with collective pitch keeps the engine spinning within a very narrow rpm range. Throttle is applied to the engine when the load increases on the engine. This was not done by metering after measuring any engine parameter in real time, before the Carb Smart came along. It was a preset set of throws which had to be adjusted by trial and error after the heli landed.
However, an airplane engine is not focused upon a very narrow rpm band, as the helicopter is focused, so it isn't likely that a heli tuned Smart Carb device will be all that useful unless collective pitch is used on the airplane, which has been done before, long, long ago.
Ed Cregger
11-12-2008, 09:42 AM
#28
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RE: In-Flight Mixture Control
Interesting thoughts ED. I use a carbsmart on my Raptor 50 and it works great. You will like it alot on your 30. My flight times went up by 3 to 4+ minutes on my Hyper 50. Your thoughts on narrow rpm band of a heli are intereting,, . But load = heat at any rpm band at what ever rpm the motor is. I think it might be worth a try because the carbsmart only uses temp as a guide to open or close the main up to 1/2 turn. [it is adjustable so you can limit throw on either end of travel]. On my carbsmart at idle it will be at its leanest setting that I set and richen under load based only on temp. I don't understand your reasoning about a narrow rpm band being a problem. Idealy you want a constant engine temp that is safe under all load conditions that is all. Maybe I am missing something here. Your thoughts?
11-12-2008, 10:30 AM
#29
RE: In-Flight Mixture Control
They're useful for adjusting the top end either in-flight or on the ground as a pose.
The problem is whether you're able to adjust the mid range for example without the specialist carb.
That's an easy test to do before you but or build in the mixture equipment.
Set up the top end and idle as normal, them go to the rich/ lean point and try twisting the needle valve.
If it cures the problem, go for the mixture equipment.
I have a 91FX and a Perry that's still rich in the midrange, even after adjusting the pump and idle needle.
Manually adjusting the needle in the mid range doesn't cure the problem because the carb isn't the type that allow midrange adjustments!
Thus for me it's pointless using the in-flight mixture controls (and I have several including OS) as they do ZIP!
Try the manual test first before you spend money and time.
The problem is whether you're able to adjust the mid range for example without the specialist carb.
That's an easy test to do before you but or build in the mixture equipment.
Set up the top end and idle as normal, them go to the rich/ lean point and try twisting the needle valve.
If it cures the problem, go for the mixture equipment.
I have a 91FX and a Perry that's still rich in the midrange, even after adjusting the pump and idle needle.
Manually adjusting the needle in the mid range doesn't cure the problem because the carb isn't the type that allow midrange adjustments!
Thus for me it's pointless using the in-flight mixture controls (and I have several including OS) as they do ZIP!
Try the manual test first before you spend money and time.
11-12-2008, 01:25 PM
#30
Senior Member
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RE: In-Flight Mixture Control
ORIGINAL: turboomni
Interesting thoughts ED. I use a carbsmart on my Raptor 50 and it works great. You will like it alot on your 30. My flight times went up by 3 to 4+ minutes on my Hyper 50. Your thoughts on narrow rpm band of a heli are intereting,, . But load = heat at any rpm band at what ever rpm the motor is. I think it might be worth a try because the carbsmart only uses temp as a guide to open or close the main up to 1/2 turn. [it is adjustable so you can limit throw on either end of travel]. On my carbsmart at idle it will be at its leanest setting that I set and richen under load based only on temp. I don't understand your reasoning about a narrow rpm band being a problem. Idealy you want a constant engine temp that is safe under all load conditions that is all. Maybe I am missing something here. Your thoughts?
Interesting thoughts ED. I use a carbsmart on my Raptor 50 and it works great. You will like it alot on your 30. My flight times went up by 3 to 4+ minutes on my Hyper 50. Your thoughts on narrow rpm band of a heli are intereting,, . But load = heat at any rpm band at what ever rpm the motor is. I think it might be worth a try because the carbsmart only uses temp as a guide to open or close the main up to 1/2 turn. [it is adjustable so you can limit throw on either end of travel]. On my carbsmart at idle it will be at its leanest setting that I set and richen under load based only on temp. I don't understand your reasoning about a narrow rpm band being a problem. Idealy you want a constant engine temp that is safe under all load conditions that is all. Maybe I am missing something here. Your thoughts?
I'm thinkin' - I'm thinkin'! <G>
Ed Cregger
11-12-2008, 02:41 PM
#31
RE: In-Flight Mixture Control
Turboomni.
In the past I did remark that the old system is mixture adjustment, when looking the way it works.
Mostly a reason for me was that using control it isn’t really the right description.
Now you show me why, because your system is really a mixture control, no adjustment.
I think about the system it is good In a heli, in normal level flight and a nearly constant position of tank versus engine and power range.
When the level of the fuel in the tank lowers the temp will rise and richen the mixture.
I think this system is designed this way because you really cannot measure the mixture in the crankcase only the effect of e lean mixture and that can be the temperature. (oxygen in the exhaust?, WEDJ do you have a sensor for that?)
In a plane I think it is better to control the pressure of the fuel near the inlet of the carb.
Look at my 61 FX, with pressure control on engine and tank.
The position of the plane and g-forces do not disturb the carb anymore, he “thinks” the tank with right and constant fuel level, is right along side him. You automatic have a constant mixture.
Temperatures I also measures and I know the temperature rises very fast when the mixture is too lean.
In the FX the result can be destroyed main ballbearing because of the wrong position of the ballbearing in the crankcase, too far afterwards after overheating and cooling down after that
About the rich midrange David, can that have to do with the normally uncontrolled (and too high?) tank pressure that is used mostly or a too high Perry pump pressure? Because I do not have problems with that, also not with my MVVS 10 cc 0.60 and MVVS 7,5 0.45.
With pressure control the inlet pressure of the fuel to the carb, after the regulator is very low, so the carb has to “suck” the fuel out of the regulator in a situation you can compare with “no tank pressure”.
So when you have a problem with a rich midrange, what happens when adjust the carb with NO tankpressure and NO pump ? Of course not to fly with it, only to see the result of adjusting on the midrange.
When it is oké than maybe a Cline regulator you can use.
Cees
In the past I did remark that the old system is mixture adjustment, when looking the way it works.
Mostly a reason for me was that using control it isn’t really the right description.
Now you show me why, because your system is really a mixture control, no adjustment.
I think about the system it is good In a heli, in normal level flight and a nearly constant position of tank versus engine and power range.
When the level of the fuel in the tank lowers the temp will rise and richen the mixture.
I think this system is designed this way because you really cannot measure the mixture in the crankcase only the effect of e lean mixture and that can be the temperature. (oxygen in the exhaust?, WEDJ do you have a sensor for that?)
In a plane I think it is better to control the pressure of the fuel near the inlet of the carb.
Look at my 61 FX, with pressure control on engine and tank.
The position of the plane and g-forces do not disturb the carb anymore, he “thinks” the tank with right and constant fuel level, is right along side him. You automatic have a constant mixture.
Temperatures I also measures and I know the temperature rises very fast when the mixture is too lean.
In the FX the result can be destroyed main ballbearing because of the wrong position of the ballbearing in the crankcase, too far afterwards after overheating and cooling down after that
About the rich midrange David, can that have to do with the normally uncontrolled (and too high?) tank pressure that is used mostly or a too high Perry pump pressure? Because I do not have problems with that, also not with my MVVS 10 cc 0.60 and MVVS 7,5 0.45.
With pressure control the inlet pressure of the fuel to the carb, after the regulator is very low, so the carb has to “suck” the fuel out of the regulator in a situation you can compare with “no tank pressure”.
So when you have a problem with a rich midrange, what happens when adjust the carb with NO tankpressure and NO pump ? Of course not to fly with it, only to see the result of adjusting on the midrange.
When it is oké than maybe a Cline regulator you can use.
Cees
11-12-2008, 04:38 PM
#32
RE: In-Flight Mixture Control
I have tried a Cline, Like it until I got air leaking into the fuel line form the regulator to the card. No idea where the air was entering, everything was glued and sealed. Still, it was unusable for me.
Have adjusted the Perry to the max point, any less pressure from the pump and it can't carry the fuel from the CG mount tank.
Point is, unless you have a carb that is designed to allow midrange mixture... like your old Webra and some new heli carbs... an in-flight mixture needle added into the equation may not fix the problem
If the engine responses to manual needle valve adjustments in the problem area, all well and good, go for the servo mixture solution.
If it doesn't... then you're wasting good money. And carrying around an extra servo.
Have adjusted the Perry to the max point, any less pressure from the pump and it can't carry the fuel from the CG mount tank.
Point is, unless you have a carb that is designed to allow midrange mixture... like your old Webra and some new heli carbs... an in-flight mixture needle added into the equation may not fix the problem
If the engine responses to manual needle valve adjustments in the problem area, all well and good, go for the servo mixture solution.
If it doesn't... then you're wasting good money. And carrying around an extra servo.
11-12-2008, 05:11 PM
#33
RE: In-Flight Mixture Control
David.
The air you are talking about, was that realy air? I do not think so!
When it was an engine with a backplate mounted needle valve it was vapor I think.
When the temperature rises, the crankcase becomes hot, so also the needle valve unit.
Evaporation of the fuel gives bubbles so the engine get more problems, leaning and more temperature rising.
I did remove the needlevalve and use an enlarged Moki carb on my Os Max 61 FX. for this reason.
I could enlarge the bore because the pressure controlles (like Cline) does his work, the carb does not have to make much "sucking" pressure.
Cees
The air you are talking about, was that realy air? I do not think so!
When it was an engine with a backplate mounted needle valve it was vapor I think.
When the temperature rises, the crankcase becomes hot, so also the needle valve unit.
Evaporation of the fuel gives bubbles so the engine get more problems, leaning and more temperature rising.
I did remove the needlevalve and use an enlarged Moki carb on my Os Max 61 FX. for this reason.
I could enlarge the bore because the pressure controlles (like Cline) does his work, the carb does not have to make much "sucking" pressure.
Cees
11-13-2008, 03:58 AM
#34
RE: In-Flight Mixture Control
David from “Aircraft and Instrument Panel Illustrations”.
I did make an illustration for you from a (spare) part of my aircraft. LOL
I did take a look in the physical date of methanol.
Methanol boils at 65 graden Celcius, 149 Fahrenheit.
65 degrees Celcius, 149 Fahrenheit, isn’t high!!
The OS Max engine backplate is normally integrated with the needle valve, see picture.
I think they later did make the unit separate so the heat conduction to the needle valve is less.
I do measure the engine head temperature near the plug normally above 150 degrees C (302 F). Overheating above 200 degrees C (392 F).
It isn't strange that in some situations , fuel, plug type, crankcase ventilation, propsize, leaning mixture, environmental circumstances (TEMP!) etc, the temp of the needle valve rises above the evaporation temp of 65 C / 149 F !!!!
(That overheating is the problem after the engine stops. this heat in the material of the head of the engine, which is a lot of material, transfers of the other parts of the crankcase.}
When using a normal OLD! carburetor, from the "pioneer days", the needle valve automatic is situated in the coldest part of the engine by the evaporation of the fuel!, also in the summer, but, yes, we with our little engines want everything the big boys have so also “vapor lock”.
Cees
I did make an illustration for you from a (spare) part of my aircraft. LOL
I did take a look in the physical date of methanol.
Methanol boils at 65 graden Celcius, 149 Fahrenheit.
65 degrees Celcius, 149 Fahrenheit, isn’t high!!
The OS Max engine backplate is normally integrated with the needle valve, see picture.
I think they later did make the unit separate so the heat conduction to the needle valve is less.
I do measure the engine head temperature near the plug normally above 150 degrees C (302 F). Overheating above 200 degrees C (392 F).
It isn't strange that in some situations , fuel, plug type, crankcase ventilation, propsize, leaning mixture, environmental circumstances (TEMP!) etc, the temp of the needle valve rises above the evaporation temp of 65 C / 149 F !!!!
(That overheating is the problem after the engine stops. this heat in the material of the head of the engine, which is a lot of material, transfers of the other parts of the crankcase.}
When using a normal OLD! carburetor, from the "pioneer days", the needle valve automatic is situated in the coldest part of the engine by the evaporation of the fuel!, also in the summer, but, yes, we with our little engines want everything the big boys have so also “vapor lock”.
Cees
11-13-2008, 07:38 AM
#35
RE: In-Flight Mixture Control
Thanks for that.
I'm using a different remote needle assembly than the stock 91fx NV.
Unfortunately, there is no transfer of heat from the engine to this NV that could be causing the bubbles in the fuel line.
The bubbles are originating from the cline. Fuel in is perfect, fuel out... bubbles.
Hummm.
Thanks anyway.
Regarding the cARBsAMART. A couple of the guys are using them down at the strip and are very happy!
I'm using a different remote needle assembly than the stock 91fx NV.
Unfortunately, there is no transfer of heat from the engine to this NV that could be causing the bubbles in the fuel line.
The bubbles are originating from the cline. Fuel in is perfect, fuel out... bubbles.
Hummm.
Thanks anyway.
Regarding the cARBsAMART. A couple of the guys are using them down at the strip and are very happy!
11-13-2008, 08:41 AM
#36
RE: In-Flight Mixture Control
David,
Than there is something wrong with that Cline, you are right.
There is a membrane inside, maybe there is a pinhole or leakage in that membrane.'
When you can find the thirt opening, so not fuel in- of outlet than maybe you can check.
Put a very little pressure, by blowing, in the outlet (to carburator) with a piece or fuel line and with the Cline under water. Closed inlet.
When you see air bubbles from the third (sensor?) opening, there is a hole in the membrane. When bubbles somewere from the casing maybe a crack in that.
I do not know the inside of the Cline, but I think it is something I show on the picture. I use also a reference to pick up the pressure near the carb.
Succes Cees
Than there is something wrong with that Cline, you are right.
There is a membrane inside, maybe there is a pinhole or leakage in that membrane.'
When you can find the thirt opening, so not fuel in- of outlet than maybe you can check.
Put a very little pressure, by blowing, in the outlet (to carburator) with a piece or fuel line and with the Cline under water. Closed inlet.
When you see air bubbles from the third (sensor?) opening, there is a hole in the membrane. When bubbles somewere from the casing maybe a crack in that.
I do not know the inside of the Cline, but I think it is something I show on the picture. I use also a reference to pick up the pressure near the carb.
Succes Cees
