NexSTAR EP is nice, but...
- Thread starter skygeezer
- Start date
Maj. Numbskully
Well-known member
that or put the fat chick in the back seat 
skygeezer said:
No, the propeller supplies the necessary propwash flowing over the rear stabilizer/elevaor to provide the force to make the stab work effectively. You don't have to have the plane going at any particluar speed. Idle/up elevator will keep the tail down on most planes.
12oclockhigh
Banned
Expo
75% expo... I have never seen that before! Read up on the subject of expo. The correct plane modification is to reduce the throw total deflection as was correctly answered. If the rudder deflection was 1-1/2 inches right and 1-1/2 inches left before, reduce both sides to 1". Another possibility, and my preferred method is to use dual rates... set full rates at 100% and low rates at 50% or sometimes a bit greater.
The chief cause of zigzaging down the runway is over control by the pilot. "Pilot induced oscillation" or pilot error are the appropriate terms. Anticipate the engine torque as RPM increases and correct for it with constant right rudder before it happens. The extreme expo is reducing your rudder movement until you have a huge stick input, not at all what you want.
I consider a 40 sized plane to be small. If you are having trouble flying that sized plane move to a 60 sized plane. They are more stable and you can see them better from a lot farther away. The cost is about the same. For my money, 60 sized is the smallest I want to fly. The reason we fly larger planes is because they are more stable. A 100 inch wing span plane of similar type is much easier to fly... it is the power that accompanies it that gets people in trouble.
Most RC guys fly tail draggers. The reason is the tricycle landing gear is inherently unstable on the ground and prone to tipover. Full down elevator helps but reduces the effectiveness of the nose wheel. It is a balance between control and tip-over. Tail draggers are not really a beginner type of airplane. The sooner the pilot learns to fly the rudder, the better off he will be.
Pilot error is usually the cause of all airplane accidents.
75% expo... I have never seen that before! Read up on the subject of expo. The correct plane modification is to reduce the throw total deflection as was correctly answered. If the rudder deflection was 1-1/2 inches right and 1-1/2 inches left before, reduce both sides to 1". Another possibility, and my preferred method is to use dual rates... set full rates at 100% and low rates at 50% or sometimes a bit greater.
The chief cause of zigzaging down the runway is over control by the pilot. "Pilot induced oscillation" or pilot error are the appropriate terms. Anticipate the engine torque as RPM increases and correct for it with constant right rudder before it happens. The extreme expo is reducing your rudder movement until you have a huge stick input, not at all what you want.
I consider a 40 sized plane to be small. If you are having trouble flying that sized plane move to a 60 sized plane. They are more stable and you can see them better from a lot farther away. The cost is about the same. For my money, 60 sized is the smallest I want to fly. The reason we fly larger planes is because they are more stable. A 100 inch wing span plane of similar type is much easier to fly... it is the power that accompanies it that gets people in trouble.
Most RC guys fly tail draggers. The reason is the tricycle landing gear is inherently unstable on the ground and prone to tipover. Full down elevator helps but reduces the effectiveness of the nose wheel. It is a balance between control and tip-over. Tail draggers are not really a beginner type of airplane. The sooner the pilot learns to fly the rudder, the better off he will be.
Pilot error is usually the cause of all airplane accidents.
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dhk79
Well-known member
I'm sorry but that's not quite correct. The use of expo has a definite purpose. It softens the responce around center allowing for finer control in this region, while still allowing for full deflection. It does not do the same thing and is normally used in conjunction with dual rates.12oclockhigh said:
Doug
opjose
Well-known member
Yes.. but 75% is a bit extreme.
This produces a marked "deadening" of the servo response around TX stick center, but it also makes travel and movement of the control surfaces very fast as the stick moves past the last 1/4 points, to max travel.
I've seen newbies try to correct for their inability to control yaw at run up, by turning up Expo to 75%.
Needless to say this only acts to exacerbate the problem!
Their plane starts to yaw or veer to one direction, so they apply rudder.
Nothing happens, so they apply more, still nothing, now the control surface slams to one side... so in a panic they push the stick the other way also overcontrolling.
The end result is their plane careens back and forth accross the runway until it takes off.
I instruct newbies to use only about 15-20% Expo for the rudder. This gives the rudder a quicker response to inputs that they can see.
If they require further deadening, I'll have them dial down the throws or adjust the linkages to reduce total travel.
This produces a marked "deadening" of the servo response around TX stick center, but it also makes travel and movement of the control surfaces very fast as the stick moves past the last 1/4 points, to max travel.
I've seen newbies try to correct for their inability to control yaw at run up, by turning up Expo to 75%.
Needless to say this only acts to exacerbate the problem!
Their plane starts to yaw or veer to one direction, so they apply rudder.
Nothing happens, so they apply more, still nothing, now the control surface slams to one side... so in a panic they push the stick the other way also overcontrolling.
The end result is their plane careens back and forth accross the runway until it takes off.
I instruct newbies to use only about 15-20% Expo for the rudder. This gives the rudder a quicker response to inputs that they can see.
If they require further deadening, I'll have them dial down the throws or adjust the linkages to reduce total travel.
12oclockhigh
Banned
Expo is not Dual Rates.
That is not what I said... I absolutely don't think 75% should ever be needed or used... (read the original post, that no one raised an issue with) by using 75% the dead center extends almost to the end of the throws.... I did not say that expo was related to dual rates...they are quite different, yet work together. You mis-read that... I said that a method of softening things is to have two rates... a low and a high rate. Agree with Opjose too. adjust the throws but the expo should not exceed 20-30%. I like to keep a lower expo to make it a livelier plane... too much expo makes it dead...
The OP was the one who used expo to deaden the response and keep it from zigzagging down the runway 75% expo - I would not think of using that...
Low Rate 50% and 20% Expo
High Rate 100% and 10% Expo
That might be an appropriate setting setting for a beginner... The throw's mechanical adjustment (servo horns) or radio travel adjustment settings would also have to be set appropriately for the particular plane.
That is not what I said... I absolutely don't think 75% should ever be needed or used... (read the original post, that no one raised an issue with) by using 75% the dead center extends almost to the end of the throws.... I did not say that expo was related to dual rates...they are quite different, yet work together. You mis-read that... I said that a method of softening things is to have two rates... a low and a high rate. Agree with Opjose too. adjust the throws but the expo should not exceed 20-30%. I like to keep a lower expo to make it a livelier plane... too much expo makes it dead...
The OP was the one who used expo to deaden the response and keep it from zigzagging down the runway 75% expo - I would not think of using that...
Low Rate 50% and 20% Expo
High Rate 100% and 10% Expo
That might be an appropriate setting setting for a beginner... The throw's mechanical adjustment (servo horns) or radio travel adjustment settings would also have to be set appropriately for the particular plane.
dhk79 said:
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Wrend
New member
I typically prefer dual rates over expo because it tends to be a little easier for me to feel what the plane is doing, and know what to expect from it. I only use expo on very acrobatic planes that really do benefit from softer controls for precision flight, but still snap when you want them to without having to flip a switch. For me, that's the exception, not the rule.
Wrend
New member
jeffpn said:
True, they're not mutually exclusive, but they're not entirely different from each other. What I mean is that I generally prefer to lower a plane's responsiveness for more subtle control using dual rates instead of expo (which could also be used), because the throws remain proportional to the stick inputs and give me a better feel for what the plane is going to do. I prefer to have my thumbs directly proportionally controlling a plane's throws, relatively speaking. More likely than not, that's just because it's what I'm used to.
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12oclockhigh
Banned
Little Bit of Expo and A dash of that.
I can fly them without expo, but they are very jittery... the fingers have some natural tremor to them that the expo obliterates. 10% is very nice for a high performance aerobatic plane... 20% is my preference for a scale plane. Try some rolling circles with my buddies 0% expo, full rates, 85cc, Wild Hare, 40%, 260 Extra sometime and you will quickly appreciate Expo and dual rates.
30% is what my WWI buddy uses on his D-VIIs, Sopwith's, Spad's and DR-1s.... I will be doing some testing soon on my 1/4 Balsa USA Sopwith Pup.. I plan to follow his lead @30% as a starting point and go from there.
I can fly them without expo, but they are very jittery... the fingers have some natural tremor to them that the expo obliterates. 10% is very nice for a high performance aerobatic plane... 20% is my preference for a scale plane. Try some rolling circles with my buddies 0% expo, full rates, 85cc, Wild Hare, 40%, 260 Extra sometime and you will quickly appreciate Expo and dual rates.
30% is what my WWI buddy uses on his D-VIIs, Sopwith's, Spad's and DR-1s.... I will be doing some testing soon on my 1/4 Balsa USA Sopwith Pup.. I plan to follow his lead @30% as a starting point and go from there.
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Wrend
New member
Don't get me wrong. I'm not trying to say that expo isn't useful. I even use it. I just tend to prefer not to use it when I don't need to. Maybe my thumbs are unusually steady or something. Who knows?
For a more vintage and scale like feel, I don't use expo at all on my WWI bipes. To each their own. What really matters is getting out their for the dawn patrol to see how the front is doing and to make sure the troops are guarded against the enemy from above.
For a more vintage and scale like feel, I don't use expo at all on my WWI bipes. To each their own. What really matters is getting out their for the dawn patrol to see how the front is doing and to make sure the troops are guarded against the enemy from above.
12oclockhigh
Banned
Agreed. My fingers/thumbs are steady to look at, but seems like there is a need for a little slop like in a car's steering wheel... you actually have to move more than a little to get a reaction. No, I don't drive a rack and pinion high performance car either. When I watch some guys make about a hundred flight corrections, I think that they are moving the sticks just to move the sticks. I try to set the surfaces and fly for a bit. I try to look smooth and it is always good to try to plan ahead.
Oh and another thing... you're late for patol, get a move on.
Oh and another thing... you're late for patol, get a move on.
Wrend said:Don't get me wrong. I'm not trying to say that expo isn't useful. I even use it. I just tend to prefer not to use it when I don't need to. Maybe my thumbs are unusually steady or something. Who knows?
For a more vintage and scale like feel, I don't use expo at all on my WWI bipes. To each their own. What really matters is getting out their for the dawn patrol to see how the front is doing and to make sure the troops are guarded against the enemy from above.