Ruder size - Bashing a single to a Twin
04-01-2014, 01:59 PM
#2
Hi Bill
That question is a little difficult as many airplanes require no increase in the vertical surface in fact many more that you might think. For example none of the popular Cadet series (sig) which are very popular for twin and sometimes three or four engines even, require additional vertical surface.
What is the subject airplane of your kit bash Bill?
John
That question is a little difficult as many airplanes require no increase in the vertical surface in fact many more that you might think. For example none of the popular Cadet series (sig) which are very popular for twin and sometimes three or four engines even, require additional vertical surface.
What is the subject airplane of your kit bash Bill?
John
04-01-2014, 09:30 PM
#3
Senior Member
Thread Starter
Dear John,
Thanks for the response.
The bash is a Superstar 40 trainer. The rudder is approximately 2" by 7 1/4". A Kadet rudder is almost twice as large.
Bill
Thanks for the response.
The bash is a Superstar 40 trainer. The rudder is approximately 2" by 7 1/4". A Kadet rudder is almost twice as large.
Bill
04-03-2014, 04:48 AM
#5
Hey Bill sorry I did not get right back, I am in the middle of painting my house.
I feel that you do not need to increase you vertical surface areas at all. Your airplane is a fine choice for a first twin. If you feel the need to increase the rudder authority then I would do it by increasing the rudder size and reducing the fin area by an equal amount, in other words just moving the hinge line forward, although its not really needed.
What I would recommend however is to use ample and equal out thrust on both sides, something on the order of 4 degrees minimum. This is far more important to important to the survivability of your ship than any increase in vertical areas. Remember while yes the cadet has more vertical surface but remember it is a far bigger airplane.
I have done considerable research on out thrust with one of my airplanes being easily variable from zero to ten degrees in just minutes, The airplane I have used for teaching some other folks on how to fly and maintain control to a landing where you want to land is adjustable for the out thrust and I do change it for each individual as they learn the technique.
John
I feel that you do not need to increase you vertical surface areas at all. Your airplane is a fine choice for a first twin. If you feel the need to increase the rudder authority then I would do it by increasing the rudder size and reducing the fin area by an equal amount, in other words just moving the hinge line forward, although its not really needed.
What I would recommend however is to use ample and equal out thrust on both sides, something on the order of 4 degrees minimum. This is far more important to important to the survivability of your ship than any increase in vertical areas. Remember while yes the cadet has more vertical surface but remember it is a far bigger airplane.
I have done considerable research on out thrust with one of my airplanes being easily variable from zero to ten degrees in just minutes, The airplane I have used for teaching some other folks on how to fly and maintain control to a landing where you want to land is adjustable for the out thrust and I do change it for each individual as they learn the technique.
John
Last edited by JohnBuckner; 04-03-2014 at 04:51 AM.
04-03-2014, 08:41 PM
#6
Senior Member
Thread Starter
Dear John,
Thanks, it should be easy to not change the rudder. Out thrust was planed at 4 degrees but it should not be too difficult to make it adjustable which had not been considered.
I have some twin experience but always treated an engine out as a total loss of power. Worked OK with many landings in very strange locations. It's time to determine if something other than glide can be accomplished with engine out.
Thanks again.
Bill
Thanks, it should be easy to not change the rudder. Out thrust was planed at 4 degrees but it should not be too difficult to make it adjustable which had not been considered.
I have some twin experience but always treated an engine out as a total loss of power. Worked OK with many landings in very strange locations. It's time to determine if something other than glide can be accomplished with engine out.
Thanks again.
Bill
04-04-2014, 05:09 AM
#7
Cool, there is no need to make out thrust adjustable unless you wanted to just experiment as I and to have it adjustable when working with others and introducing them to the joys of sustained single engine flight with a twin (or more) 
To sustain flight on one engine there is going to be a very simple pilot reaction required but it is not intuitive and most pilots no matter how experienced will imput the wrong control. That most important reaction is the application of rudder into the good engine and lots of it, in most cases all the rudder. What most will do is use ailerons into the good engine (or aginst the direction of yaw) and this is the worst thing you can do and will promote even more Yaw into the dead engine.
Now the tendency is for most once they may have applied the rudder appropriately into the good engine they will simply let right back off the rudder instinctively and this is a killer. That rudder must be held an kept pinned into the good engine as long as power is maintained on that engine. This technique will result in skidding flight but fully controllable and actually easy just keep the rudder pinned and use the ailerons to control all the turns.
Yes partial power reductions will result in need for the rudder but most find it very easy to simply keep the rudder pinned and drive the airplane around with the ailerons. Agine this is not intuitive and but works increditably well and if you think about it is very close to full scale technique not quite but close.
Now lets talk about how to identify which engine is out and believe me this is the most difficult part of all and the full scale pilots have it easy compared to what we have to do? I have used the expression 'dead foot, dead engine' thousands of time teaching full scale multi but that is useless of course for us. For me all the fellows I have helped with this is simply put as one word and that is practice and knowing how you airplane will behave with engine out senarios and at different airspeeds and power settings.
So how does one get this practice? Well here is the technique I used for myself and others and there is no need for independent throttle setups or complicated electronic systems. All of the multics I have done have used simple Y corded throttles and that includes many twins several triples two quads and one all the way up to six engines. The procedure is a simple one I call short tanking, simply filling one fuel tank only partially. Now by doing this for your first engine outs you will already know which engine is going to stop and it will give you the opportunity to think about before the flight and rehearse in your mind the application of the rudder and not the aileron. You will just fly a nice pattern with good altitude until the known engine quits and remember most engine stoppages very confusingly are not clean stops. Doing this on both sides is very beneficial and then working with someone else unknown short tanks should be practiced, that will provide the ultimate challenge and perhaps why we fly these wonderful multi's
John
To sustain flight on one engine there is going to be a very simple pilot reaction required but it is not intuitive and most pilots no matter how experienced will imput the wrong control. That most important reaction is the application of rudder into the good engine and lots of it, in most cases all the rudder. What most will do is use ailerons into the good engine (or aginst the direction of yaw) and this is the worst thing you can do and will promote even more Yaw into the dead engine.
Now the tendency is for most once they may have applied the rudder appropriately into the good engine they will simply let right back off the rudder instinctively and this is a killer. That rudder must be held an kept pinned into the good engine as long as power is maintained on that engine. This technique will result in skidding flight but fully controllable and actually easy just keep the rudder pinned and use the ailerons to control all the turns.
Yes partial power reductions will result in need for the rudder but most find it very easy to simply keep the rudder pinned and drive the airplane around with the ailerons. Agine this is not intuitive and but works increditably well and if you think about it is very close to full scale technique not quite but close.
Now lets talk about how to identify which engine is out and believe me this is the most difficult part of all and the full scale pilots have it easy compared to what we have to do? I have used the expression 'dead foot, dead engine' thousands of time teaching full scale multi but that is useless of course for us. For me all the fellows I have helped with this is simply put as one word and that is practice and knowing how you airplane will behave with engine out senarios and at different airspeeds and power settings.
So how does one get this practice? Well here is the technique I used for myself and others and there is no need for independent throttle setups or complicated electronic systems. All of the multics I have done have used simple Y corded throttles and that includes many twins several triples two quads and one all the way up to six engines. The procedure is a simple one I call short tanking, simply filling one fuel tank only partially. Now by doing this for your first engine outs you will already know which engine is going to stop and it will give you the opportunity to think about before the flight and rehearse in your mind the application of the rudder and not the aileron. You will just fly a nice pattern with good altitude until the known engine quits and remember most engine stoppages very confusingly are not clean stops. Doing this on both sides is very beneficial and then working with someone else unknown short tanks should be practiced, that will provide the ultimate challenge and perhaps why we fly these wonderful multi's
John
04-04-2014, 11:17 AM
#8
Twin model flying is different to real flying because we don't have our bum in the cockpit.
Our first reaction is to visual input.
Flying a model the first we see of an engine out is a uncommanded roll, the first we hear is a change of engine sound. As the model yaws with the engine out it also rolls and our reaction is to correct the roll.
The moment you think an engine out, put full rudder in the same direction as you have the aileron. lock the rudder in and let the aileron back to neutral. Keep the nose level and the throttle and speed up.
All this should happen in 2-3sec.
For power vs rudder corrections, Power IN Rudder IN, Power OFF Rudder OFF.
With radios these days we can set throttles up on seperate channels and use mixs as well. It gives you total control over individual idle trims and top end, it allows for assymetric training by mixing and condition
switching to lock a engine at idle and recover on command or shut down any engine.
Our first reaction is to visual input.
Flying a model the first we see of an engine out is a uncommanded roll, the first we hear is a change of engine sound. As the model yaws with the engine out it also rolls and our reaction is to correct the roll.
The moment you think an engine out, put full rudder in the same direction as you have the aileron. lock the rudder in and let the aileron back to neutral. Keep the nose level and the throttle and speed up.
All this should happen in 2-3sec.
For power vs rudder corrections, Power IN Rudder IN, Power OFF Rudder OFF.
With radios these days we can set throttles up on seperate channels and use mixs as well. It gives you total control over individual idle trims and top end, it allows for assymetric training by mixing and condition
switching to lock a engine at idle and recover on command or shut down any engine.
