P-51 Mustang Brotherhood
02-28-2016, 03:02 PM
#752
acdii,
When you add power on takeoff and the tail comes up, the plane yaws left. Some pilots attempt to beat this by lifting off prematurely causing the left wing to stall, and drag a wingtip, and it can turn into a disastrous cartwheel/crash. In forward flight, a sudden application of power coupled with up elevator (pitch up) causes a right yaw/right wing stall and if too low to recover, a crash. Both of these stalls are a result of the torque/'P' factor/gyroscopic precession forces overcoming the airframe's positive stability and causing a departure from controlled flight. The gyroscopic precession is the dominant force here. In the case of the pitch down at the 'tail lifting' point of takeoff the yaw is to the left. In flight, the pitch up causes the opposite yaw, to the right. The correct control to use is the rudder, not aileron to lift the low wing tip.
The inflight condition is also an accelerated stall, which is a stall occurring well above the normal low speed stall. Full scale pilots are taught to "keep the ball centered' during turns by the correct amount of rudder to center the ball. The pilot is trained to 'step on the ball' using the correct rudder pedal.
RC pilots are not in the cockpit with a needle and ball to use for this so must compensate by limiting the applied pitch rate so as not to enter this type of 'loss of controlled flight'.
RC pilots who are used to the oversized vertical fin/rudder most trainers or sport planes/3D planes have to provide built in yaw stability in these planes are surprised when they discover a condition of flight they never experienced before-when they transition to Scale Models of full scale aircraft.
Usually, a primary design feature of full scale aircraft is tail surfaces sized to provide adequate stability and maximum fuel economy (minimum drag) for their designed purpose. For this reason many full scale aircraft are placarded against certain maneuvers (stalls, slow rolls, exceeding 'G" force limits, etc.). For instance, P 51 aircraft were restricted from high G maneuvers with a 'full' aft fuselage tank (the wings would tear off at the gun-bays), caused by the resulting accelerated stall. They were restricted from high speed slow rolls after horizontal tail surfaces failed causing fatalities or captured pilots. The correct P 51 roll is a positive 'G' roll or 'barrel' roll with up elevator applied to maintain at least 1 'G' even when inverted.
Experienced RC P51 pilots use the model manufacturer's elevator control throws and either get used to applying smooth, gradual application of elevator or even use exponential to soften initial elevator response. It is not the amount of elevator applied that causes accelerated stalls, it is the RATE off of neutral. And the hotter the weather, the more likely you will experience one of these high speed stalls. A high speed turn at low altitude aggravated by turbulence and the plane will snap into the ground before you are even aware there is a problem. At high altitude it may do an outside snap into an inverted flat spin (always fun to figure out even with adequate altitude).
When you add power on takeoff and the tail comes up, the plane yaws left. Some pilots attempt to beat this by lifting off prematurely causing the left wing to stall, and drag a wingtip, and it can turn into a disastrous cartwheel/crash. In forward flight, a sudden application of power coupled with up elevator (pitch up) causes a right yaw/right wing stall and if too low to recover, a crash. Both of these stalls are a result of the torque/'P' factor/gyroscopic precession forces overcoming the airframe's positive stability and causing a departure from controlled flight. The gyroscopic precession is the dominant force here. In the case of the pitch down at the 'tail lifting' point of takeoff the yaw is to the left. In flight, the pitch up causes the opposite yaw, to the right. The correct control to use is the rudder, not aileron to lift the low wing tip.
The inflight condition is also an accelerated stall, which is a stall occurring well above the normal low speed stall. Full scale pilots are taught to "keep the ball centered' during turns by the correct amount of rudder to center the ball. The pilot is trained to 'step on the ball' using the correct rudder pedal.
RC pilots are not in the cockpit with a needle and ball to use for this so must compensate by limiting the applied pitch rate so as not to enter this type of 'loss of controlled flight'.
RC pilots who are used to the oversized vertical fin/rudder most trainers or sport planes/3D planes have to provide built in yaw stability in these planes are surprised when they discover a condition of flight they never experienced before-when they transition to Scale Models of full scale aircraft.
Usually, a primary design feature of full scale aircraft is tail surfaces sized to provide adequate stability and maximum fuel economy (minimum drag) for their designed purpose. For this reason many full scale aircraft are placarded against certain maneuvers (stalls, slow rolls, exceeding 'G" force limits, etc.). For instance, P 51 aircraft were restricted from high G maneuvers with a 'full' aft fuselage tank (the wings would tear off at the gun-bays), caused by the resulting accelerated stall. They were restricted from high speed slow rolls after horizontal tail surfaces failed causing fatalities or captured pilots. The correct P 51 roll is a positive 'G' roll or 'barrel' roll with up elevator applied to maintain at least 1 'G' even when inverted.
Experienced RC P51 pilots use the model manufacturer's elevator control throws and either get used to applying smooth, gradual application of elevator or even use exponential to soften initial elevator response. It is not the amount of elevator applied that causes accelerated stalls, it is the RATE off of neutral. And the hotter the weather, the more likely you will experience one of these high speed stalls. A high speed turn at low altitude aggravated by turbulence and the plane will snap into the ground before you are even aware there is a problem. At high altitude it may do an outside snap into an inverted flat spin (always fun to figure out even with adequate altitude).
02-28-2016, 04:52 PM
#753
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sjhanc, great explanation. I have, of course, read so much about how the P51 requires close attention and proper control inputs for successful flight and your explanation really makes it clear why.
Thank you.
Mike
Thank you.
Mike
02-28-2016, 06:11 PM
#754
acdii,
When you add power on takeoff and the tail comes up, the plane yaws left. Some pilots attempt to beat this by lifting off prematurely causing the left wing to stall, and drag a wingtip, and it can turn into a disastrous cartwheel/crash. In forward flight, a sudden application of power coupled with up elevator (pitch up) causes a right yaw/right wing stall and if too low to recover, a crash. Both of these stalls are a result of the torque/'P' factor/gyroscopic precession forces overcoming the airframe's positive stability and causing a departure from controlled flight. The gyroscopic precession is the dominant force here. In the case of the pitch down at the 'tail lifting' point of takeoff the yaw is to the left. In flight, the pitch up causes the opposite yaw, to the right. The correct control to use is the rudder, not aileron to lift the low wing tip.
The inflight condition is also an accelerated stall, which is a stall occurring well above the normal low speed stall. Full scale pilots are taught to "keep the ball centered' during turns by the correct amount of rudder to center the ball. The pilot is trained to 'step on the ball' using the correct rudder pedal.
RC pilots are not in the cockpit with a needle and ball to use for this so must compensate by limiting the applied pitch rate so as not to enter this type of 'loss of controlled flight'.
RC pilots who are used to the oversized vertical fin/rudder most trainers or sport planes/3D planes have to provide built in yaw stability in these planes are surprised when they discover a condition of flight they never experienced before-when they transition to Scale Models of full scale aircraft.
Usually, a primary design feature of full scale aircraft is tail surfaces sized to provide adequate stability and maximum fuel economy (minimum drag) for their designed purpose. For this reason many full scale aircraft are placarded against certain maneuvers (stalls, slow rolls, exceeding 'G" force limits, etc.). For instance, P 51 aircraft were restricted from high G maneuvers with a 'full' aft fuselage tank (the wings would tear off at the gun-bays), caused by the resulting accelerated stall. They were restricted from high speed slow rolls after horizontal tail surfaces failed causing fatalities or captured pilots. The correct P 51 roll is a positive 'G' roll or 'barrel' roll with up elevator applied to maintain at least 1 'G' even when inverted.
Experienced RC P51 pilots use the model manufacturer's elevator control throws and either get used to applying smooth, gradual application of elevator or even use exponential to soften initial elevator response. It is not the amount of elevator applied that causes accelerated stalls, it is the RATE off of neutral. And the hotter the weather, the more likely you will experience one of these high speed stalls. A high speed turn at low altitude aggravated by turbulence and the plane will snap into the ground before you are even aware there is a problem. At high altitude it may do an outside snap into an inverted flat spin (always fun to figure out even with adequate altitude).
When you add power on takeoff and the tail comes up, the plane yaws left. Some pilots attempt to beat this by lifting off prematurely causing the left wing to stall, and drag a wingtip, and it can turn into a disastrous cartwheel/crash. In forward flight, a sudden application of power coupled with up elevator (pitch up) causes a right yaw/right wing stall and if too low to recover, a crash. Both of these stalls are a result of the torque/'P' factor/gyroscopic precession forces overcoming the airframe's positive stability and causing a departure from controlled flight. The gyroscopic precession is the dominant force here. In the case of the pitch down at the 'tail lifting' point of takeoff the yaw is to the left. In flight, the pitch up causes the opposite yaw, to the right. The correct control to use is the rudder, not aileron to lift the low wing tip.
The inflight condition is also an accelerated stall, which is a stall occurring well above the normal low speed stall. Full scale pilots are taught to "keep the ball centered' during turns by the correct amount of rudder to center the ball. The pilot is trained to 'step on the ball' using the correct rudder pedal.
RC pilots are not in the cockpit with a needle and ball to use for this so must compensate by limiting the applied pitch rate so as not to enter this type of 'loss of controlled flight'.
RC pilots who are used to the oversized vertical fin/rudder most trainers or sport planes/3D planes have to provide built in yaw stability in these planes are surprised when they discover a condition of flight they never experienced before-when they transition to Scale Models of full scale aircraft.
Usually, a primary design feature of full scale aircraft is tail surfaces sized to provide adequate stability and maximum fuel economy (minimum drag) for their designed purpose. For this reason many full scale aircraft are placarded against certain maneuvers (stalls, slow rolls, exceeding 'G" force limits, etc.). For instance, P 51 aircraft were restricted from high G maneuvers with a 'full' aft fuselage tank (the wings would tear off at the gun-bays), caused by the resulting accelerated stall. They were restricted from high speed slow rolls after horizontal tail surfaces failed causing fatalities or captured pilots. The correct P 51 roll is a positive 'G' roll or 'barrel' roll with up elevator applied to maintain at least 1 'G' even when inverted.
Experienced RC P51 pilots use the model manufacturer's elevator control throws and either get used to applying smooth, gradual application of elevator or even use exponential to soften initial elevator response. It is not the amount of elevator applied that causes accelerated stalls, it is the RATE off of neutral. And the hotter the weather, the more likely you will experience one of these high speed stalls. A high speed turn at low altitude aggravated by turbulence and the plane will snap into the ground before you are even aware there is a problem. At high altitude it may do an outside snap into an inverted flat spin (always fun to figure out even with adequate altitude).
02-28-2016, 07:14 PM
#755
acdii,
I use 30% expo on both of my Giant scale P 51 model's elevators. I still have to use a smooth touch with no jerking of the sticks. P 51 flight controls are relatively powerful needing little actual travel for good control. With an onboard camera aimed at the surfaces there is only small movements even when doing aerobatic maneuvers. Back when I was having a lot of trouble nosing over and breaking props every 4-5 flights I did a lot of experimenting with tail-wheel strut design. I discovered a hobby shop part, I believe it is a Sullivan tail wheel strut that gave superior bounce control so I installed one in the D model I was flying at the time. I used that same strut in several succeeding Mustangs until recently when I realized it was too flexible side-to-side for positive steering on takeoff and landing.
I bought some larger diameter wire and a Higley wire bender and copied the Sullivan design. The result gives me excellent ground handling and still has good bounce control. If I can get the thread tools to co-operate I will up load a picture.
The strut installation is important for best results. I had to modify the TopFlite mounting to get the strut's pivot axis vertical to the ground when the tailwheel is down on the ground. The stock mount aligns the tailwheel strut vertical only when the tail is flying with the wheel in the air. As soon as the wheel touches the ground the steering axis is incorrect and crosswinds can stall the servo and even reverse the steering, especially if there is any slope to taxi over. When properly installed the tail wheel is slightly in front of the vertical strut. This put a neutral load on the servo in crosswind conditions.
I use 30% expo on both of my Giant scale P 51 model's elevators. I still have to use a smooth touch with no jerking of the sticks. P 51 flight controls are relatively powerful needing little actual travel for good control. With an onboard camera aimed at the surfaces there is only small movements even when doing aerobatic maneuvers. Back when I was having a lot of trouble nosing over and breaking props every 4-5 flights I did a lot of experimenting with tail-wheel strut design. I discovered a hobby shop part, I believe it is a Sullivan tail wheel strut that gave superior bounce control so I installed one in the D model I was flying at the time. I used that same strut in several succeeding Mustangs until recently when I realized it was too flexible side-to-side for positive steering on takeoff and landing.
I bought some larger diameter wire and a Higley wire bender and copied the Sullivan design. The result gives me excellent ground handling and still has good bounce control. If I can get the thread tools to co-operate I will up load a picture.
The strut installation is important for best results. I had to modify the TopFlite mounting to get the strut's pivot axis vertical to the ground when the tailwheel is down on the ground. The stock mount aligns the tailwheel strut vertical only when the tail is flying with the wheel in the air. As soon as the wheel touches the ground the steering axis is incorrect and crosswinds can stall the servo and even reverse the steering, especially if there is any slope to taxi over. When properly installed the tail wheel is slightly in front of the vertical strut. This put a neutral load on the servo in crosswind conditions.
Last edited by sjhanc; 03-01-2016 at 03:21 PM.
02-28-2016, 08:07 PM
#756
I regularly fly my planes in strong crosswinds when others are sitting it out. The P 51 especially is able to operate safely in 15-18 mph winds up to 20 degrees off the runway centerline. I make a lot of trips to distant club fields for warbird events and in Florida the wind can be a problem. I will try to fly as long as the crosswind is steady, not gusty. I lower the upwind wing a little to cancel the drift and hold opposite rudder all the way to the tail dropping after the ground runout. The approach speed is always a little faster to have a safety factor in case the wind stops suddenly. My tailwheel is on its own channel slaved to the rudder but it has 85% exponential so that I can move the rudder a long way while the tail steering hardly moves at all. This allows straight tracking when the TW is effective but a lot of crosswind rudder at the same time. For taxi steering the rudder is near its limit to give small radius turns in the taxiways. The real P 51 uses a different mechanical arrangement to get almost the same effect that I get with my model's steering.
Years ago I took others advice to limit the use of flaps in strong, gusty winds but now I use full flaps with confidence in any flyable wind conditions. This way I have a lot of power on during the approach and landing and the P 51 handles wind conditions better than most other designs excepting P 47 models. I used to fly at a club field that had some rough bumps and a small hill near the middle of the runway. I began to use 20 degrees of takeoff flaps with 30% elevator up trim to relieve the strain on the retracts and this worked much better. After getting used to this flap setting for grass I began to use it on hardtop runways also, it shortens the takeoff run.
Years ago I took others advice to limit the use of flaps in strong, gusty winds but now I use full flaps with confidence in any flyable wind conditions. This way I have a lot of power on during the approach and landing and the P 51 handles wind conditions better than most other designs excepting P 47 models. I used to fly at a club field that had some rough bumps and a small hill near the middle of the runway. I began to use 20 degrees of takeoff flaps with 30% elevator up trim to relieve the strain on the retracts and this worked much better. After getting used to this flap setting for grass I began to use it on hardtop runways also, it shortens the takeoff run.
02-28-2016, 08:24 PM
#757
I also play with the CG until I find the 'sweetspot'. This is the TopFlite GS Mustang's recommended 4 9/16 inches back from the kink in the leading edge of the wing. After much moving forward and then back I ended at the recommended CG as the best location. With my Hanger 9 Mustang I started in the middle of the range, then moved it rearward 5 times until I got no further improvement, then moved it forward 1/4 inch and that is where I like it. One thing I discovered about the H 9 plane is that knife edge flight is better with the forward CG, the further back I moved it the more pitch coupling I saw, and at the most tail heavy CG it was hard to hold it in knife edge. The H 9 Mustangs CG range is so large it should be able to satisfy any pilot.
Last edited by sjhanc; 02-28-2016 at 09:19 PM.
02-28-2016, 09:40 PM
#758
acdii,
I'm thinking that full throttle rpm is causing a vibration that causes an aileron or rudder servo to malfunction giving a right control movement. I had that problem with my Robart electric retracts. The retracts would not work over 1/3 throttle. You might test it by having a couple friends hold the model off the ground while you apply full throttle.
Ralph
I'm thinking that full throttle rpm is causing a vibration that causes an aileron or rudder servo to malfunction giving a right control movement. I had that problem with my Robart electric retracts. The retracts would not work over 1/3 throttle. You might test it by having a couple friends hold the model off the ground while you apply full throttle.
Ralph
02-29-2016, 09:59 AM
#759
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But what causes a hard RIGHT snap with power, and speed not being factors in a stall? It is a fast 90* change in direction to the right. The plane was never slow enough for a wing tip stall as it was still at 1/4 throttle on approach, I only drop to idle once I cross the threshold. I have done low passes with it at 1/4 throttle and its moving pretty good too. It only happens at full throttle and up elevator.
Acdii as aircraft get heavier they become more sensitive to quick changes in directions. did you pull E before it snapped?
story time:
I used to fly 704 SCALE combat (while they still looked like planes) I would ignore the manufacturers suggestion for elevator throw and set it for 30 degrees setting the other dual rate for 12 degrees. after it was trimmed out at a safe hight with high rate E at full throttle I would pull a hard elevator and the plane would snap. the plane would continue the snap till I released the E. it would snap to the first wing to stall but the snap would always be a angle from the original direction 20 degrees left or right and 20 degree climb. it would track on that heading till I release the E (I had 1.25hp on a 2# plane). my spotter would then reduce the 30 degrees electronically and I would try it again till it did not snap any more.
now what did you do going into the snap did you pull E? r u aft CG?
02-29-2016, 10:25 AM
#760
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sjhanc,
Your posts have been very enjoyable to read and very helpful towards my understanding of the aerodynamics at play with the P51. Thanks for taking the time to write.
Mike
Your posts have been very enjoyable to read and very helpful towards my understanding of the aerodynamics at play with the P51. Thanks for taking the time to write.
Mike
Last edited by mikedj; 02-29-2016 at 10:27 AM. Reason: spelling
02-29-2016, 11:13 AM
#761
Acdii as aircraft get heavier they become more sensitive to quick changes in directions. did you pull E before it snapped?
story time:
I used to fly 704 SCALE combat (while they still looked like planes) I would ignore the manufacturers suggestion for elevator throw and set it for 30 degrees setting the other dual rate for 12 degrees. after it was trimmed out at a safe hight with high rate E at full throttle I would pull a hard elevator and the plane would snap. the plane would continue the snap till I released the E. it would snap to the first wing to stall but the snap would always be a angle from the original direction 20 degrees left or right and 20 degree climb. it would track on that heading till I release the E (I had 1.25hp on a 2# plane). my spotter would then reduce the 30 degrees electronically and I would try it again till it did not snap any more.
now what did you do going into the snap did you pull E? r u aft CG?
story time:
I used to fly 704 SCALE combat (while they still looked like planes) I would ignore the manufacturers suggestion for elevator throw and set it for 30 degrees setting the other dual rate for 12 degrees. after it was trimmed out at a safe hight with high rate E at full throttle I would pull a hard elevator and the plane would snap. the plane would continue the snap till I released the E. it would snap to the first wing to stall but the snap would always be a angle from the original direction 20 degrees left or right and 20 degree climb. it would track on that heading till I release the E (I had 1.25hp on a 2# plane). my spotter would then reduce the 30 degrees electronically and I would try it again till it did not snap any more.
now what did you do going into the snap did you pull E? r u aft CG?
I was going to weigh it and see what it is, but it now has a Saito 125 instead of the GK 100 in it, so the weight is not what it was when the incident happened, that and there is some added wood to the plane from the repairs, so it will be heavier now than when I first flew it.
02-29-2016, 01:15 PM
#762
acdii,
As in full scale aircraft, scale model aircraft need gentle application of power on and power off. The stronger the motor the gentler you must be. Scale model aircraft do not obey the rules of RC sport and 3D aerodynamics. Scale models almost always have smaller wing area and tail surfaces and the wing loading is much higher than sport and 3D. The pilots who always recommend you use a nose heavy CG forget that this will increase the angle of attack and stall angle at all speeds making the plane ALWAYS closer to its critical stall angle AT ANY SPEED. You should maiden the plane at the middle of the manufacturer's recommended CG range and test it at high altitude to see what happens when it stalls. Nose heavy planes, when stalled in level flight usually just drop the nose and lose altitude until the pilot releases up elevator and recovers. What they don't tell you is that in other stall conditions, sometimes violent and unpredictable snap stalls occur, and depending on how much air is left makes quick judgment calls necessary to get a stall recovery.
On the other hand, properly balanced planes have a lower angle of attack in flight and more room before the critical stall angle is reached. This translates to a plane that is more responsive to less control input, has a lower level stall speed, and is much less likely to get into an accelerated stall when maneuvering. Take the CG just a smidgen more tail heavy and you have a beast that can't slow up for landing and won't easily recover from a stall or stall-spin because it is trying to backup when stalled. At approach and landing and even low takeoff speed a tail heavy plane will snap and head for the hard place.
When I am fine tuning the CG on a plane type that is new to me I start at the recommended CG and add small amounts of rearward CG change (never more than 1/8 inch at a time, or 1/16 inch on smaller planes), until I see a slight porpoise in pitch in level flight (or no improvement from the last CG change). Don't be tempted to try aerobatics until the CG is like you want it. Then when I think I have found the most rearward CG for the plane I move the CG back toward nose heavy 1/4 inch for Giant scale or 1/8-1/16 inch for smaller planes.
The pilots who try to get you to set CG by using their favorite climbing/diving pitch change test are usually flying an light, aerobatic model with oversized control surfaces. I know how to do that but don't use it on scale models. A sport/3D model with huge horizontal/vertical surfaces will fly successfully even when it is grossly tail heavy because the oversize tail moves the center of lift way back on the wing. This is how 3D planes are able to hover and do high alpha maneuvers close to the ground, given a high power to weight ratio.
That being said, I will never recommend that a pilot stall test his heavy warbird. Even if it has forgiving stall characteristics there may not be enough altitude for a recovery. If you want to practice your stall recovery skills, use a sport plane and wring it out, it is cheaper and it will teach you the necessary instinctive reflex actions you may need for that warbird. When I am flying my warbirds I am always on the lookout for the slightest hint of a departure from my planned flight path.
As in full scale aircraft, scale model aircraft need gentle application of power on and power off. The stronger the motor the gentler you must be. Scale model aircraft do not obey the rules of RC sport and 3D aerodynamics. Scale models almost always have smaller wing area and tail surfaces and the wing loading is much higher than sport and 3D. The pilots who always recommend you use a nose heavy CG forget that this will increase the angle of attack and stall angle at all speeds making the plane ALWAYS closer to its critical stall angle AT ANY SPEED. You should maiden the plane at the middle of the manufacturer's recommended CG range and test it at high altitude to see what happens when it stalls. Nose heavy planes, when stalled in level flight usually just drop the nose and lose altitude until the pilot releases up elevator and recovers. What they don't tell you is that in other stall conditions, sometimes violent and unpredictable snap stalls occur, and depending on how much air is left makes quick judgment calls necessary to get a stall recovery.
On the other hand, properly balanced planes have a lower angle of attack in flight and more room before the critical stall angle is reached. This translates to a plane that is more responsive to less control input, has a lower level stall speed, and is much less likely to get into an accelerated stall when maneuvering. Take the CG just a smidgen more tail heavy and you have a beast that can't slow up for landing and won't easily recover from a stall or stall-spin because it is trying to backup when stalled. At approach and landing and even low takeoff speed a tail heavy plane will snap and head for the hard place.
When I am fine tuning the CG on a plane type that is new to me I start at the recommended CG and add small amounts of rearward CG change (never more than 1/8 inch at a time, or 1/16 inch on smaller planes), until I see a slight porpoise in pitch in level flight (or no improvement from the last CG change). Don't be tempted to try aerobatics until the CG is like you want it. Then when I think I have found the most rearward CG for the plane I move the CG back toward nose heavy 1/4 inch for Giant scale or 1/8-1/16 inch for smaller planes.
The pilots who try to get you to set CG by using their favorite climbing/diving pitch change test are usually flying an light, aerobatic model with oversized control surfaces. I know how to do that but don't use it on scale models. A sport/3D model with huge horizontal/vertical surfaces will fly successfully even when it is grossly tail heavy because the oversize tail moves the center of lift way back on the wing. This is how 3D planes are able to hover and do high alpha maneuvers close to the ground, given a high power to weight ratio.
That being said, I will never recommend that a pilot stall test his heavy warbird. Even if it has forgiving stall characteristics there may not be enough altitude for a recovery. If you want to practice your stall recovery skills, use a sport plane and wring it out, it is cheaper and it will teach you the necessary instinctive reflex actions you may need for that warbird. When I am flying my warbirds I am always on the lookout for the slightest hint of a departure from my planned flight path.
02-29-2016, 05:09 PM
#765
I have done a ton of stall tests with my T-Clips, and Cub, just never had a chance to stall test, at least low speed stall, with the stang. If it wasn't for trying that cross wind landing, I probably would have figured out the problem and still be flying it. My Cub is a tricky bird, it will stay airborne at a slow speed, but once it hits its stall, it flops down, which on landing is a PITA. I can get a high AOA on it before it drops a wing, the problem I get is that when I try to land it in a 3 point fashion, it just floats nose high while climbing until it stalls. Very sensitive to elevator at low speed, just a touch on landing will put it back in the air. This is all most likely due to it being way over powered with a 15x6 prop on it.
Now if I can get my P-51 to fly again, hopefully I can figure out the quirks and have some fun with it.
What I do when I get a fresh plane is trim it out and land it to see how it handles on landing. Then I fill it back up and take off and put it through some maneuvers to see what it does with each control, aileron rolls, elevator loops and rudder turns, then put it up way high and cut to idle and keep adding up E until it drops to see what its reaction is and just how slow it can go, then I flip it on its back and do the same thing.
I didn't do this with the Mustang mainly because of the snapping it did under power, and I was learning how it works with flaps. I was still in the tweaking stages before I put it through its paces to see what it can do when I flipped it in.
The one plane I have done some aww crap things with is my Somethin Extra. I was having engine issues with it cutting out at half a tank, and it cut out when I was at the wrong end of the field and it went behind trees on me, so it took a beating. Got it repaired and replaced the engine with a Saito72 which ran great through a full tank, so the problem is with the OS 70 I had on it, or the RX, which I also switched out to a Futaba from the Spectrum I had in there, so it was either the RX going to failsafe for a brief moment killing the engine, though why half tank, unknown, but more likely it is the carb. The second time I had a Aww Crap moment is when I forgot to put the rubber band on the hatch, the magnets wouldnt hold it down, and it came off in flight and completely upset how it flew, and it stalled way sooner than it normally does.
Well anyway, when it is running good and the hatch is secured, I can harrier land it at a high AoA, or slip it in with a strong cross wind, so I got the skills to land the Mustang, just have to learn its limits, and hopefully with what everyone suggested with CG and such, I can figure out how to eliminate that damned snapping at high speed.
PS forgot to mention I fly a Twin Otter with full flaps, and have my 4*120 setup with flaperons, so been practicing landings with flaps. The TO is definitely not an easy plane to fly, if you slow it down too much it will drop its nose and head for the ground very quickly. It will stall in a high bank turn if not enough power is applied. Right now its on the bench getting its belly repaired from it getting too far down the runway for me to judge its speed and it stalled nose first 2 feet straight down ripping the gear out. Lesson learned there, go around when its too far down. When on a proper approach with full flaps it comes in slightly nose high with just a touch of power on, and just before touching down, kill the power and it settles in nicely, my last landing it was too high coming in, and I should have gone around as I could not judge its speed.
Now if I can get my P-51 to fly again, hopefully I can figure out the quirks and have some fun with it.
What I do when I get a fresh plane is trim it out and land it to see how it handles on landing. Then I fill it back up and take off and put it through some maneuvers to see what it does with each control, aileron rolls, elevator loops and rudder turns, then put it up way high and cut to idle and keep adding up E until it drops to see what its reaction is and just how slow it can go, then I flip it on its back and do the same thing.
I didn't do this with the Mustang mainly because of the snapping it did under power, and I was learning how it works with flaps. I was still in the tweaking stages before I put it through its paces to see what it can do when I flipped it in.
The one plane I have done some aww crap things with is my Somethin Extra. I was having engine issues with it cutting out at half a tank, and it cut out when I was at the wrong end of the field and it went behind trees on me, so it took a beating. Got it repaired and replaced the engine with a Saito72 which ran great through a full tank, so the problem is with the OS 70 I had on it, or the RX, which I also switched out to a Futaba from the Spectrum I had in there, so it was either the RX going to failsafe for a brief moment killing the engine, though why half tank, unknown, but more likely it is the carb. The second time I had a Aww Crap moment is when I forgot to put the rubber band on the hatch, the magnets wouldnt hold it down, and it came off in flight and completely upset how it flew, and it stalled way sooner than it normally does.
Well anyway, when it is running good and the hatch is secured, I can harrier land it at a high AoA, or slip it in with a strong cross wind, so I got the skills to land the Mustang, just have to learn its limits, and hopefully with what everyone suggested with CG and such, I can figure out how to eliminate that damned snapping at high speed.
PS forgot to mention I fly a Twin Otter with full flaps, and have my 4*120 setup with flaperons, so been practicing landings with flaps. The TO is definitely not an easy plane to fly, if you slow it down too much it will drop its nose and head for the ground very quickly. It will stall in a high bank turn if not enough power is applied. Right now its on the bench getting its belly repaired from it getting too far down the runway for me to judge its speed and it stalled nose first 2 feet straight down ripping the gear out. Lesson learned there, go around when its too far down. When on a proper approach with full flaps it comes in slightly nose high with just a touch of power on, and just before touching down, kill the power and it settles in nicely, my last landing it was too high coming in, and I should have gone around as I could not judge its speed.
Last edited by acdii; 02-29-2016 at 05:16 PM.
02-29-2016, 06:11 PM
#766
Cubs are not as easy to land as everyone thinks they are. There are a lot of them at the fields I fly at and they do more than their share of takeoff ground loops, slow stalls at 10 feet on landing, then going nose down into the rough, or my favorite, the ground loop during landing that ends up inverted 200 feet out. This last maneuver always closes the runway until he can walk slowly out to the plane, stand there scratching his head, pick it up and drag ass back to the pits. All the while several other orbiting planes are now running low on fuel waiting for the runway to open.
03-01-2016, 03:19 AM
#767
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Well Boys and Girls I have issues in River City, oppps I meant Riverside 
If you want to see a stall check out this camera angle video: I was able to do some over the top wing overs and stalls.
With my Bud Nosen I like to "Depart" and "Recover", with this plane I try to tickle "Departing" and stay ever so close to the feathered edge. Not easy to do with no power or idle speed, but I said I would post video if it made into the air and this topic is Perfect timing for my new training. I am going to TATTOO some of these comments on my forearms!!!
At the 11:00 minute mark in the video I will gain altitude for a vertical tail slide and with out top end power to control the nose I will cause departure and nose over in a fast wide pendulum swing past inverted to a negative dive angle with no positive control - Using altitude I let the nose drop to vertical gaining speed and pull out but on the edge of elevator snap. Had I been lower I would have maintain the inverted dive and pushed out inverted with gradual power. Either way there is loss of control with vertical loss of altitude and high risk of snapping it all the way down - Fun Fun Fun but an altitude hungry maneuver and you need to be dialed in on the elevator.
A day of Bad luck & forced luck. Looks like the diaphragm finally failed on the 3W 120 inline twin on a tuned pipe. I could not get it started yesterday.
I broke it down, soaked the diaphragm in fuel and still could not get it to idle or reach top end. On the last ounce of energy I had at the end of the day it finally started but with no idle or top end response.
By that time I was so frustrated I just pointed it to the wind, pushed the throttle forward and did what I could do with what I had. Maintaining high RPM to keep it running with no top-end means it was not the flight I was looking for; so I will have to come back and do it again however i did get to play with it just enough to make the day awesome!
I have just transferred the plane program from a DX18 onto my new Stealth without any hassle and (not having idle or a top end speed) The slow flying was perfect to dial in new flap and elevator settings.
I broke it down, soaked the diaphragm in fuel and still could not get it to idle or reach top end. On the last ounce of energy I had at the end of the day it finally started but with no idle or top end response.
By that time I was so frustrated I just pointed it to the wind, pushed the throttle forward and did what I could do with what I had. Maintaining high RPM to keep it running with no top-end means it was not the flight I was looking for; so I will have to come back and do it again however i did get to play with it just enough to make the day awesome!
I have just transferred the plane program from a DX18 onto my new Stealth without any hassle and (not having idle or a top end speed) The slow flying was perfect to dial in new flap and elevator settings.
If you want to see a stall check out this camera angle video: I was able to do some over the top wing overs and stalls.
With my Bud Nosen I like to "Depart" and "Recover", with this plane I try to tickle "Departing" and stay ever so close to the feathered edge. Not easy to do with no power or idle speed, but I said I would post video if it made into the air and this topic is Perfect timing for my new training. I am going to TATTOO some of these comments on my forearms!!!
At the 11:00 minute mark in the video I will gain altitude for a vertical tail slide and with out top end power to control the nose I will cause departure and nose over in a fast wide pendulum swing past inverted to a negative dive angle with no positive control - Using altitude I let the nose drop to vertical gaining speed and pull out but on the edge of elevator snap. Had I been lower I would have maintain the inverted dive and pushed out inverted with gradual power. Either way there is loss of control with vertical loss of altitude and high risk of snapping it all the way down - Fun Fun Fun but an altitude hungry maneuver and you need to be dialed in on the elevator.
.
video starts just after take off, flying slow, down and dirty Hoover style until I adjust the radio settings I need then its gear up test and a couple of times around the horn and then to the landing, which is way fast to keep her running but I get lucky and set it down using the 25+mph breeze down the runway.
All in all a good day but hard work vs. lazy Sunday at the field.
The Handheld Camera also failed so this is what I captured: https://youtu.be/zEC6dr6Gk1o
<iframe width="350" height="197" src="https://www.youtube.com/embed/zEC6dr6Gk1o" frameborder="0" allowfullscreen></iframe>
Sent from my iPhone
All in all a good day but hard work vs. lazy Sunday at the field.
The Handheld Camera also failed so this is what I captured: https://youtu.be/zEC6dr6Gk1o
<iframe width="350" height="197" src="https://www.youtube.com/embed/zEC6dr6Gk1o" frameborder="0" allowfullscreen></iframe>
Sent from my iPhone
Last edited by simple; 03-01-2016 at 03:43 AM.
03-01-2016, 09:59 AM
#768
Cubs are not as easy to land as everyone thinks they are. There are a lot of them at the fields I fly at and they do more than their share of takeoff ground loops, slow stalls at 10 feet on landing, then going nose down into the rough, or my favorite, the ground loop during landing that ends up inverted 200 feet out. This last maneuver always closes the runway until he can walk slowly out to the plane, stand there scratching his head, pick it up and drag ass back to the pits. All the while several other orbiting planes are now running low on fuel waiting for the runway to open.
03-01-2016, 12:15 PM
#769
My long time pit helper, spotter and camera man is fascinated by Cubs, he will turn the Camera on any Cub that flies during an event. As a result of this we have a large video library of Cub flying accidents. I should put together a youtube video of Cub misadventures but I didn't want to come off as overly critical of Cubs and their pilots. They are the reason I installed 32 ounce fuel tanks in my Mustangs-so I would be able to cruise around for an extra 10-15 minutes and still have enough fuel for several approaches. I was frustrated after several close calls nearly running out of fuel. On several occasions my engine ran dry on final approach or during the landing run and I had to make the walk of shame to drag my plane back. Now if a Cub takes off after I have been flying for 5 minutes I will cut my flight short and land immediately. At the pilot's meeting Heavy Metal warbird pilots are instructed to always fly a racetrack pattern so that mid-air conflicts are minimized, we all fly more or less together in a loose formation, even doing maneuvers together. If a Cub takes off during this they will fly a random, unpredictable flight requiring the warbird spotters to watch the Cub and advise their pilots how to fly to avoid a collision with the almost stationary obstacle in the airspace. Strangely, I have observed this same behavior by one of the jet-jockeys at my club field. He's a lot faster but always flying in the wrong direction.
03-01-2016, 05:53 PM
#770
Well, I can bet my Cub can almost keep up with your Mustang! LOL With the Saito 100 and a 14x6 prop it will take off like an F-15, Straight Up and just climb. The downside is it takes forever to slow down enough to land
03-03-2016, 11:43 AM
#771
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Shout out to my guys in Warbirds West!!
Got to put a shout out to my buddies in Warbirds West. These guys got my old bones out of medical treatment and out to the field to make this flight happen.
Carb. diaphragm issues kept me from prolonged idle and top end performance but we found a middle ground and I got a mid-range flight and out of the Hospital for an excellent day of RC Warbirds West flying. Shout out to Sam, Michael, Tim, Tim, Brian, Jamie and the family with the BBQ Spanish tacos ready to feed an army of pilots "Warbirds West Rules"
Maiden of Michael's Zirole P-40 "awsome" https://www.facebook.com/warbirdswest/
Flight of my bird with on-board micro cams = https://youtu.be/76mUu-bku9M
<iframe width="400" height="225" src="https://www.youtube.com/embed/76mUu-bku9M" frameborder="0" allowfullscreen></iframe>
Carb. diaphragm issues kept me from prolonged idle and top end performance but we found a middle ground and I got a mid-range flight and out of the Hospital for an excellent day of RC Warbirds West flying. Shout out to Sam, Michael, Tim, Tim, Brian, Jamie and the family with the BBQ Spanish tacos ready to feed an army of pilots "Warbirds West Rules"
Maiden of Michael's Zirole P-40 "awsome" https://www.facebook.com/warbirdswest/
Flight of my bird with on-board micro cams = https://youtu.be/76mUu-bku9M
<iframe width="400" height="225" src="https://www.youtube.com/embed/76mUu-bku9M" frameborder="0" allowfullscreen></iframe>
03-04-2016, 06:52 AM
#772
Hello guys, I would like to ask if somebody here is interested in some parts for Ziroli´s P-51D Mustang.
I thinking to list a spinner, fibreglass cowl and air intake. So I would like to ask you about your opinion.
I thinking to list a spinner, fibreglass cowl and air intake. So I would like to ask you about your opinion.
03-08-2016, 11:21 PM
#774
I perform stall tests with every plane I fly including my TF Mustang. Slow flight, stalls and flap elevator mix tests with the gear up and down so I know as much as possible how each plane will respond in any configuration. When the guys in the club ask me to maiden a plane we go over everything and in flight I talk thru the maneuvers with the owner as a spotter. That way they get a good read on the model with me.
The TF Mustang I have is very docile as Mustangs go I think. I've flown it in high winds and cross winds and it is very positive and stable. In winds above 15mph I can easily pull power back to 1/3 and just float and cruise around like a powered scale slope soaring model. I've tried this with different flap settings and even hovered it with no problems. I had one moment when I pushed it too far and it stalled with a roll to the left. It came on predictably and with the right inputs and power it recovered quickly.
The Mustangs rudder is pretty effective on crosswind landings. You must get used to flying it with rudder, it's your friend. Literally 90 degree wind change just before landing and the wind was in the 10mph range but the Mustang handled it great.
To fly a Mustang like this takes practice, confidence, and a well set up plane. You have to invest the time in flying in poor weather and flying technical or touchy planes. You need to fly different types of planes. The guys I see that fly only or mostly one type, like IMAC, usually have problems with more scale planes because of their lack of understanding with them. They're used to chucking planes around with large control surfaces and scale planes are just the opposite.
My advice to would be scale pilots is to fly in all kinds of weather and as many different kinds of planes as you can.
The TF Mustang I have is very docile as Mustangs go I think. I've flown it in high winds and cross winds and it is very positive and stable. In winds above 15mph I can easily pull power back to 1/3 and just float and cruise around like a powered scale slope soaring model. I've tried this with different flap settings and even hovered it with no problems. I had one moment when I pushed it too far and it stalled with a roll to the left. It came on predictably and with the right inputs and power it recovered quickly.
The Mustangs rudder is pretty effective on crosswind landings. You must get used to flying it with rudder, it's your friend. Literally 90 degree wind change just before landing and the wind was in the 10mph range but the Mustang handled it great.
To fly a Mustang like this takes practice, confidence, and a well set up plane. You have to invest the time in flying in poor weather and flying technical or touchy planes. You need to fly different types of planes. The guys I see that fly only or mostly one type, like IMAC, usually have problems with more scale planes because of their lack of understanding with them. They're used to chucking planes around with large control surfaces and scale planes are just the opposite.
My advice to would be scale pilots is to fly in all kinds of weather and as many different kinds of planes as you can.
03-09-2016, 10:15 AM
#775
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Hello everyone. I have been reading all the information about the bad things that happen with the P-51. Yes I agree it can be a handfull to fly. Has anyone here had any experiance with the World Models P-51 GS? It has a 80.6" wing span and it is powered with a DLE 35 RA and a 20 x 8 prop. Any input would be greatly appreciated