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HelicopterMain Discussion › gyro in twin engine plane
08-06-2007 09:34 AM  10 years agoPost 1
muz

rrNovice

Reefton(west coast)

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hi can any one help me i have a twin dual ace twin engine plane and am thing about puting a gy401 gyro in it on the rudder to help keep the plane under control if one engine cuts out will this be a good idea cheers muz

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08-06-2007 01:22 PM  10 years agoPost 2
SSN Pru

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Taxachusetts

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you shouldnt rely on electronics to help you incase of an engine out.

Ive flown twin engine planks for years and never had a problem. If you understand the basic physics of flight and you are a good enough pilot without bad habits, then you wont have a problem with twin engine airplanes.

I used to take my Hobbico Twin star off on one engine and fly around an entire tank on one engine all the while doing aerobatics...

If you really want a gyro on there then dont use the 401, you dont need heading hold. All you need is a cheap rate gyro.

Be aware though that there are a lot of situations involving one engine out that a gyro just wont help you. The only help youll have is quick reflexes and good thumbs!

Stupidity can be cured. Ignorance is for life!

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08-06-2007 03:23 PM  10 years agoPost 3
Pistol Pete

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Seffner, FL

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Have you considered placing the gyro for the elevator instead?

This will keep her in level flight while you worry about yaw control as it seems to be your main preocupation.

~~Enjoying the hobby one flight at a time~~

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08-06-2007 03:54 PM  10 years agoPost 4
SSN Pru

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Taxachusetts

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that would work as long as the aircraft didnt roll. Generally, with an engine out, you are going to get a yaw coupled roll too. then your in trouble.

the best bet for twin engine safety is a good working knowledge of what to do when the fecal matter hits the ventilation. A good set of thumbs doesnt hurt either.

The most critical situation to experience engine out is on takeoff. If you get an engine out on takeoff you are most likely going to crash if you dont detect it right away. During takeoff, both engines are at high power and airspeed is low. When the airspeed is low, the rudder has a much lower effectiveness.

Some design points to minimize yaw with engine out:

Use counter rotating engines. This isnt very practical with RC.

Basically, you should always practice turning away from the dead engine and not towards it. If you turn towards it, the asymmetrical thrust will help to "overturn" your aircraft and you'll probably end up in a spin right into the dirt.

The best bit of information regarding design is to add some offset to the engines. Generally, 3 degrees outward will help a TON! The offset thrust line will generally help to counter-act the asymmetrical thrust when an engine goes out.

When i first got into twins, I had an ATX Stylux TX which had sliders available on the upper corners of the radios. I was able to program the radio such that a switch would allow one engine to be idled while the other engine was under control of the throttle stick. I would get up high and practice my engine out procedures by using this method and it helped me to learn a lot about emergencies. Having a father with over 9000 hours instructing in varous A/C including multi engines didnt hurt either...

Stupidity can be cured. Ignorance is for life!

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08-06-2007 05:13 PM  10 years agoPost 5
BarracudaHockey

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Jacksonville FL

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Put some out thrust in the engines, it will handle engine out alot better.

And as someone said, you dont really want heading hold in an airplane, use a piezo rate gyro.

Andy
AMA 77227
http://www.jaxrc.com

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08-06-2007 05:37 PM  10 years agoPost 6
skyhawk172n

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Forest, MS USA

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"can't remember which is the critical engine...." The one that just quit is ALWAYS the critical engine when flying a multi, whether a model or f/s
BTW, the general rule is never turn INTO the dead engine, always away from it. It's generally not a problem with lightly loaded model multis. On F/S twins or heavily loaded models (think P-38) the engine torque can easily overcome rudder effectivness at low airspeed.
Roy

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08-06-2007 06:57 PM  10 years agoPost 7
SSN Pru

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Taxachusetts

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can't remember which is the critical engine...." The one that just quit is ALWAYS the critical engine when flying a multi, whether a model or f/s
While you are correct that, anytime you loose an engine, it is critical, I was refering to the fact that IF you do lose an engine, there is ONE ENGINE that you would rather have not quit. that engine is the right engine (just called my father, over 9500 hrs and a former CFI). The reason being, the torque reaction will tend to "roll" the aircraft into the right engine if the (the dead one). If the left engine were to quit, then the torque reaction would roll the aircraft into the working engine.

you never want to roll into the dead engine, EVER!
It's generally not a problem with lightly loaded model multis.
I dont know what your experience is with multi engine RC models, but I have quite a bit. It is a rare thing to have a "lightly loaded" multi model...

The power to weight ratio may be good, but the wing loadings are still going to be rather high compared to a similar sized single engine A/C. With an engine out, you arent only concerned with power loading but arguably more so the wing loading.

Stupidity can be cured. Ignorance is for life!

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08-07-2007 12:28 AM  10 years agoPost 8
skyhawk172n

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Forest, MS USA

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I was referring to your paragraph beginning " use counter rotating engines" In it you mention practicing turning into the dead engine as the preferred method. This is quite backward to the flight training I have recieved over the years both in F/S and models, but feel free to use your own experiences...

Referring to 'lightly loaded models' I was talking about trainers converted to twin or even tri-motor configuration. Yes, the loading is higher than as a single, but usually quite acceptable.

My crack about the critical engine was an attempt at a joke that goes around in aviation circles, similar to the one about what the second engine in a light twin is for. The answer; to get you to the scene of the crash faster!

Good luck either way, just trying to help.

Roy

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08-07-2007 12:59 AM  10 years agoPost 9
SSN Pru

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Taxachusetts

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Yeah, that got screwed up in an edit when i first posted the thing.

The simplest way to fly multi's is to use counter rotating engines so you dont have a critical engine...

you never want to turn into a dead engine if you can avoid it.

Stupidity can be cured. Ignorance is for life!

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08-07-2007 08:48 AM  10 years agoPost 10
Paul Woodcock

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Dubai - United Arab​Emirates

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Hey guys

Twins are not monsters.

If you loose an engine on a twin MODEL and you are out of control....just close the throttle......make it a glider, roll wings level and regain control.....Why fight an out of control machine into the ground.

If you are low, like on a take-off....land straight ahead...Like you would with a single. Better to do an out landing than a crash.

If you are high.....when you are ready, gradually open the throttle and catch the yaw with rudder. For the landing, come in a bit high and low power, then you have limited yaw issues.

Even i can do this.

Regards

Paul

PS: The left engine on most multi-engine machines is the critical engine. The aircraft will be flying nose up because of the low speed. The up comming blade will have a longer helix path to travel in the same time as the down going blade. This will offset the thrust on either engine to the left. So inboard for the right engine and outboard for the left....making the yaw worse on the left engine.

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08-07-2007 12:40 PM  10 years agoPost 11
SSN Pru

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Taxachusetts

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I should also add that most models are designed with larger rudders and vertical stabs if they are designed for twin engines. They do this because of their "monster" reputation with one engine out.

Proper practice and training is most useful. Above all else, get out and experiment. Like I said earlier, I purposefully idled 1 engine on most of my flights and had a blast with it doing all sorts of aerobatics. It's pretty neat to see an 80 in. twin dong rolling 360's on one engine...

Its also pretty cool to take-off on one engine. I only did that once and got it back down in one piece haha. I was bored...

Stupidity can be cured. Ignorance is for life!

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08-07-2007 10:53 PM  10 years agoPost 12
Two Left Thumbs

rrKey Veteran

Houston, Texas - USA

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How about an FMA Copilot?

http://www.fmadirect.com/detail.htm...1489§ion=20

I have not flown a twin, but seems this would be a big help when you loose an engine and cannot react quickly enough.

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08-08-2007 12:55 AM  10 years agoPost 13
SuperSixTwo

rrVeteran

Virginia City, NV​---USA

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fma in twin

I have the fma on the heli, and would expect that it would work fine.
You could also use the GYA 352 which is a dual axis gyro. The best answer is practice and stick time. Just like our full size counterparts, knowing what to do and when to do it comes with experience. Remember though, that with slow airspeeds all control surfaces have low air flow so dont expect that either a gyro or the fma will save your bacon. It might try to, but not be capable of it if your too slow or to close to the ground.

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08-08-2007 02:43 AM  10 years agoPost 14
SSN Pru

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Taxachusetts

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a gyro wont save you if you are in an unusual attitude, ie. spiraling towards the ground.

only your thumbs, eyes, and brain will save your a/c then.

I personally wouldnt recommend using a gyro to help with engine out on a twin, it simply isnt needed.

Stupidity can be cured. Ignorance is for life!

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08-08-2007 07:47 AM  10 years agoPost 15
Paul Woodcock

rrElite Veteran

Dubai - United Arab​Emirates

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Hi guys

If you want to put an electronic 'thing' to help you....put a single axis gyro with normal setings. ie non HH. Put it on the rudder...like a heli.

Dont use a FMA CoPilot or a 2 or 3 axis gyro. I say this because, when the engine fails.....it will start to yaw. Lets say left engine fails (no. 1) the plane will yaw left. If uncorrected, it will start to roll to the left and then enter a spiral dive to the left. You MUST recover with right rudder only. If you use right aileron to try and level the wings, you will be creating even more drag on the left and more left yaw and make the situation worse....

Most pictures of twins crashing....especially movies you can see the ailerons in full, with no rudder correction......and the pilot wondered why he lost control. The problem is, with a model, you are not sitting in it so you don't feel the initial yaw. The first thing most people will see will be the roll and they will instinctively correct with ailerons....This will happen even more easily when there are other planes flying and you can't hear your engines....in this case engine!!!

This is why i said earlier, if you have lost control, close the power and remove the problem. Once you have regained control, slowly open the one engine. Better to have a controled glide than an out of control crash....

Another thing to consider would be on a 3-position switch, put in a rudder mix. When an engine fails, after you have the correct rudder input in, flick the switch to give 1/4 rudder in the correct direction. On full size aircraft, there usually is a 'magic' rudder trim setting. On the A330, it is 6 sec of elecrtic trim. On the B737 it was 2 turns. This 'magic' setting works, because you fly at a set speed and only removed just before landing.

Hope this helps.

Paul

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08-08-2007 01:15 PM  10 years agoPost 16
SSN Pru

rrElite Veteran

Taxachusetts

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I'd have to disagree with the "Only use rudder" to correct for an unusual attitude after engine failure. Sure rudder is requried to stabilize the assymetrical thrust and resultant yaw but a lot of A/C dont have very good roll-to-yaw coupling which means you can apply all the rudder you want and you are only going to get a yaw. The application of BOTH rudder AND aileron would be the better bet.

I would wager a bet that most multi engine rated pilots out there are undertrained and have never experienced an engine out situation. Ive read several first hand account of pilots loosing an engine and not being able to detect which one was out in time because of panic.

You say that most videos or pictures showing engine out wrecks show the use of aileron and not rudder. This indicates a fundamental lack of training in primary flight. The first rule of thumb: if you roll, you use aileron, unless you are performing aerobatics. My father engrained and stressed this point so much that whenever I fly now its second nature. Its not that way with every pilot though.

Stupidity can be cured. Ignorance is for life!

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08-08-2007 02:05 PM  10 years agoPost 17
Paul Woodcock

rrElite Veteran

Dubai - United Arab​Emirates

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Hi guys

Yes, i do agree that you do need rudder and aileron to correct from an unusual attitude and elevator for that matter.

BUT

Most models are 'straight' wing with little or no sweep. The engine out situation will create mainly a yaw and little roll. The innitial yaw correction should be ONLY rudder. Then the roll can then be corrected with aileron. I used to fly twins piston powered machines and practiced engine-out alot. Both simulated and real.....

A gyro would help to correct the innitial yaw very well.

The high sweep of a jet aircraft, that i now fly, makes the roll much worse and you do innitially correct the roll with ailerons and then use rudder to straighten it all out....

Paul

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