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Author Topic: Right-right trim and random P-30 thougths  (Read 1283 times)
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Jukka Juslin
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« on: October 17, 2011, 12:35:14 PM »


Dear All,

First, a true mystery in my head is why right-right trim (climb to right and glide to right) is so popular? It makes no sense in the context of physics, because the propeller causes torque to left and you get more aerodynamic penalties when try to force it to right. Quite tight spiral to left in the start of climb would not necessarely hurt that much, as does with the same stab setting a straight climb - does not work always that good without additional down elevator.

So, in order to put the plane to right circle in the climb you will loose energy because in addition to fighting the torque you will even put it to go right. Then another point is that I have had several Pee-Wee models (now since August 2011 even the carbon Pee-Wee) and they really have hard time on right-right. One person had idea that it might be due tu so large rudder and that seemed to impact it. But over all I think longer flying times would be attained with left-left. It just means to reworking all the warps and stab settings again, which costed so much valuable flying time, and in addition quite a lot of money went to this right-right experiment.

Then some random P-30 thoughts, which have nothing to do much with this right-right issues (necessarily). I started some months ago here a discussion on wind speeds. I personally settled to 2 m/s as pretty much the maximum. Other than that it is better to continue building I think. The flying field sizes what I have don't provide much chances for higher winds.

One strange thing about my P-30 flying is that I seem to be so interested now in calm weather flying. It like flying indoor outside, but without a roof and getting fresh air. One concrete chance for this, which I already used and tested is night flying at a Finnish airport. There additional plus is that it is very silent during the night and you can operate freely. During the day you could not operate freely because of all the flying traffic. One big minus thing is of course, that is physically quite hard at least at first to stay up all night. You need to change your rhythm. But I see currently no other way to attain the best trims.

I hope the day would come that I feel like the trims are okay and I can start flying during day also. One absolute requirement for daytime flying is of course the timer and a working fuse system. Of course this should be self-evident, but many self-evident things really end up being non-self evident. I have a tendency for example to forget turning on the timer. There are of course various solutions for this, but I think for me best working would be a check-list, like what the real pilots have. Only other thing, that might not be evident at launch is adding a rubber to old the nose together after the rubber runs out of turns.

I think thermal flying with my mylar streamer could be interesting. Wind limitations apply, though. But it really would require a little bit of space. It is a pity, that I don't have or there is no RC D/T device for P-30 and also getting electronic timer to work with my resources doesn't see that attainable now.

Jukka
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Jukka Juslin
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« Reply #1 on: October 17, 2011, 12:47:33 PM »

Hello again,

I wanted to add one more thing: I really like flying with the RAM-3 logger. That ends the endless speculations about "how high". And potentially you could get more scientific view to the flight and glide. Of course again as many others, this way of action is pretty much created by Tapio Linkosalo. It gives meaning to compare the log results to his results. I try to post all good logs also this forum - it is just I don't have very many working cases, because as usual limited energy, money and time to spend on this issue. Every summer big flying session-dreams usually end up with one night of flying, but I think I continue dreaming anyway. With model airplanes just sometimes feels like the harsh reality is no match to the dreams Smiley

Jukka

P.S. The reason why night flying at summer in Finland works, is that Finland is almost at the arctic circle, and the sun never sets on arctic circle during a few weeks of mid-summer.
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crashcaley
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« Reply #2 on: October 17, 2011, 01:45:05 PM »

Jukka, I can understand how you feel.  Many have the same problem.  Many young people have to earn a living, take care of family things, and that definitely puts a roadblock in model airplane building and flying.  Retirees have it a lot better, but not always.
  Though never as far up north as you are, I can remember a few times in my military service where it seemed we only got four or five hours of night.  That does make for more time to do things out of doors if you have an opportunity.  Glad you have a few weeks that you find you have an opportunity to fly and experiment.
  Do you have any flying pals?  I know that would make things a lot more enjoyable, if you do.  I lack local flying pals when it comes to free flight.
  Best wishes on your endeavours in the technical parts of our hobby.  It does sound interestin, though a bit over ny non techie head.  Caley
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Jukka Juslin
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« Reply #3 on: October 17, 2011, 01:55:26 PM »

Jukka, I can understand how you feel.  Many have the same problem.  Many young people have to earn a living, take care of family things, and that definitely puts a roadblock in model airplane building and flying.  Retirees have it a lot better, but not always.
  Though never as far up north as you are, I can remember a few times in my military service where it seemed we only got four or five hours of night.  That does make for more time to do things out of doors if you have an opportunity.  Glad you have a few weeks that you find you have an opportunity to fly and experiment.
  Do you have any flying pals?  I know that would make things a lot more enjoyable, if you do.  I lack local flying pals when it comes to free flight.
  Best wishes on your endeavours in the technical parts of our hobby.  It does sound interestin, though a bit over ny non techie head.  Caley

Caley,

Flying pals are usually not too many. You are right, that is very very important aspect. Though, on the other hand we strive to be independent, but in the end we are really not. Everybody depends on others. Went quite philosophical Smiley

I have looked at some advertizements, when people sell all their FF planes. There usually a given reason (probably needed to give a reason) is lack of local support.

Jukka
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Jukka Juslin
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« Reply #4 on: October 20, 2011, 10:45:27 PM »

Ok, nobody knows about the right-right vs. left-left trim? That is a pity.

I guess I just have to experiment then without much theoretical thoughts.

Jukka
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danberry
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« Reply #5 on: October 21, 2011, 01:29:13 PM »

You're probably gonna crash flying left/left.
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Dave Andreski
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« Reply #6 on: October 21, 2011, 01:35:53 PM »

You're probably gonna crash flying left/left.

Dan's right.
Dave Andreski
« Last Edit: October 21, 2011, 02:01:30 PM by Dave Andreski » Logged

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Dave Andreski
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« Reply #7 on: October 21, 2011, 01:48:31 PM »

JUKKA,
P-30 flyers know about it. YOU don't Huh
Dave Andreski
« Last Edit: October 21, 2011, 02:02:42 PM by Dave Andreski » Logged

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applehoney
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« Reply #8 on: October 21, 2011, 02:17:05 PM »

Right/left with most folders

Right/right with most freewheelers

Left/left  ...    with very few of either type.
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RalphS
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« Reply #9 on: October 21, 2011, 02:21:52 PM »

Jukka -  if you had put this query in the "Aerodynamics" part you may have had a well reasoned reply from Hepcat.  I know that Hepcat is not too keen on P30 - something to do with plastic props, so he may have missed this thread.

Coming from a radio control background I know that attempting any flat(ish) turn needs crossed controls and requires the model to yaw presenting lots of fuselage side area to the turn which requires more power to keep the yaw going.  So I think that I agree with your conclusions.  However, with rubber powered freeflight models, trying to turn left with the the torque reaction trying to bank the model left results, I understand, in an ever increasing spiral dive.  So the easy way to stop this happening is to turn right under power.  On the glide the model can glide left or right. Most people keep the right turn going because if you have waited for that thermal to come through and get the model into lift it is better to stay with it rather than change direction and go out of the lift.

I am not sure but I believe that indoor fliers usually fly left hand circles.  The models are much lower powered and perhaps a little bit of bank helps to keep them turning tightly and probably stops them climbing too high.  I don't know if this is correct because my views on indoor flying are similar to Hepcats views on P30 and I don't get to see it Grin.

Anyway my comments may draw some fire from others who are better informed and get some feedback for you.

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Jukka Juslin
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« Reply #10 on: October 22, 2011, 08:49:33 AM »

JUKKA,
P-30 flyers know about it. YOU don't Huh
Dave Andreski

Dave,

Sorry about making you unhappy.

I have flown a lot of indoor and P-30.

Jukka
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Dave Andreski
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« Reply #11 on: October 22, 2011, 04:47:23 PM »

Jukka,
Make ME unhappy? I don't think so.
My post was in response to your statement -"Ok, nobody knows about the right-right vs. left-left trim? That is a pity."
I find nothing pitiful about the info available on this forum.
If you fly P-30, then why the question?
Dave Andreski

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Hepcat
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« Reply #12 on: October 24, 2011, 05:14:27 PM »

Ralph (Spadge) you know me too well but how can any aeromodeller like P30 when you are forced to buy the propeller?  Real aeromodellers make things they don’t buy them.  Strange, but I think I had some influence on your first P30.

JJ your physics training must be much more advanced than mine if you can assess the energy required for different trim movements.  It is easy to see the energy required for straight flight is Drag x Velocity but the minute differences with trim elude me.  However I do feel that the amount required to yaw the model, as when initiating a turn should be quite small, a little trim tab on a long moment arm and directional damping is not usually high.  On the other hand roll damping is high with both wings resisting movement and complete wing panels are often given a different incidence setting to give a roll effect. 

A symmetrical glider set to turn in either direction will tighten its turn and in the end will spiral dive unless there is a lot of dihedral.  A powered model will do the same except that the motor torque will be trying to roll the model to the left.  The left roll combined with the left turn will spiral dive the model much sooner but the left roll combined with a right turn will give a right spiral climbing upwards.  In the right turn case the roll from motor torque is reducing the need for incidence increase on the right wing and probably reducing energy loss.

Indoor models will climb better turning to the right but a good climb is rarely a primary consideration indoors so, in general, indoor models have had their aerodynamics optimized for a left turn.

I don’t think that that adds much to what others have said but it shews my support for their point of view.

John
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« Reply #13 on: October 25, 2011, 02:44:21 PM »

My thoughts.

You can trim for left-left, but the margin for error is very slim for outdoor models, largely due to the amount of power used.  At launch, with the motor putting out much more thrust (as much as 50% more than cruise), the reaction is a STRONG left torque.  This must be counter-acted, and having a right spiral climb trim is much more forgiving (less sensitive to adjustments).  I'm one of the ones that believe a right-left flight pattern actually gains the most altitude, but it also leaves your model circling the opposite direction of most thermal circulations (in the northern hemisphere, when the thermal HAS a circulation), and is less likely to stay in a thermal as long.

Even in low-wing models where the trim IS often left-left, the prop is often set for both right and downthrust to keep from arcing into the ground at launch.  For indoor models, as mentioned, the power is much less, and a successful left-left flight pattern works - and even helps to keep the model away from the walls.

Your question also leads me to my strategy during trimming - look first to take OUT a trim before you add one, and see if that can solve the problem.  In other words, if you have the rudder set for a right turn, and the model enters a right-right "death spiral", think about reducing the right rudder before you add that tab to the right wing to "hold it up" in the turn.  If the model NEEDS more right during the power phase, think about a touch of right thrust, not putting the rudder back in. . . . and at the end of the session, take a look a where you ended up, and where you started - do all the adjustments make sense, or are some of them opposing each other?

Justin
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« Reply #14 on: November 26, 2012, 12:07:05 PM »

Jukka:
A right-right trim produces a steeper climb profile. A steeper climb results in more altitude in the same amount of time ( assuming the same power/no. of turns) Altitude gained=time aloft. Time aloft =contest wins.
The "ultimate" rubber powered models are probably Wakefields, NO ONE that I am aware of flys a Wakefield to the left. If that does not convince you to fly right, you must be a "leftist" Grin Grin

Bob
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« Reply #15 on: November 26, 2012, 12:12:42 PM »

I'd have to disagree with at least part of what you said Bob. A right climb is proper for outdoor duration models, but I don't see why Right/Right would give a steeper climb over Right/Left. Unless you are just talking about the climb direction in which case .... "never mind" ;-)

By the way, my flying buddy Cameron Ackerley flies all of his Wakefields to the left! However, he does wing "backwards" so all of the trim settings are exact mirror images of the Right climb settings. At every World Champs I've been with him the time keepers are freaked out when he launches! They assume there is some sort of mistake..... Shocked

Tmat
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« Reply #16 on: November 26, 2012, 12:38:53 PM »

Tmat, of course I was addressing climb, and I was talking outdoor duration models. Since the subject of the thread was right-right trim as applied to P-30's. As noted, no one that I am familar with flies Wakefields to the left, as usual, there are always exceptions Roll Eyes As I recall, Doug Joyce always flew canards in F1C.
If I recall correctly, Joyce was not particularlly successful in F1C.  I am not familar with Akerly's record in F1B, but I do not remember seeing his name high on the list at World Championships.
Please correct me if I am mistaken.
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« Reply #17 on: November 26, 2012, 01:22:10 PM »

Cameron was part of the winning Canadian F1B team at the 1993 World Championships. I think he finished 12th?
His model is an exception in that he winds it in the reverse direction so his prop rotates in the clockwise direction (when viewed from the front). Thus the left hand climb is the "correct" direction with respect to prop rotation. He's left handed so does everything "backwards".
When we flew locked down models his reverse winding made sense as he could launch the model with a left bank with his left hand. I've told him that with today's Wakefield models with delayed prop release it doesn't matter which way the prop rotates as they all begin the climb straight up and straight ahead. Indeed lefty Bernard Guest chose to fly F1B with a Right/Right climb and wind the "right way" rather than complicate matters for himself. Cameron's models all require special custon left hand prop blades and hubs as well as timers on the opposite side of the model etc.

Tmat
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« Reply #18 on: November 26, 2012, 07:21:15 PM »

Jukka, basic explaination: right thrust to achieve a right climb gives a very nose up climb during the initial power (and torque) burst, transitioning to a good cruise attitude as the torque decreases. With a left circle during the power burst, you waste altitude with a shallow or flat attitude until the power is reduced. Why would you want this?
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« Reply #19 on: November 29, 2012, 11:10:44 AM »

Cameron was part of the winning Canadian F1B team at the 1993 World Championships. I think he finished 12th?
His model is an exception in that he winds it in the reverse direction so his prop rotates in the clockwise direction (when viewed from the front). Thus the left hand climb is the "correct" direction with respect to prop rotation. He's left handed so does everything "backwards".
When we flew locked down models his reverse winding made sense as he could launch the model with a left bank with his left hand. I've told him that with today's Wakefield models with delayed prop release it doesn't matter which way the prop rotates as they all begin the climb straight up and straight ahead. Indeed lefty Bernard Guest chose to fly F1B with a Right/Right climb and wind the "right way" rather than complicate matters for himself. Cameron's models all require special custon left hand prop blades and hubs as well as timers on the opposite side of the model etc.

Tmat
The important thing to note here is that a nose-high climb is achived by flying against torque. No matter if you choose to build conventional?? models with props turning counter-clockwise (as viewed from the nose) or clockwise for "left handed" props.
The majority of low-wing scale models being flown are flown to the left, as it is considered "safer". I try to fly EVERY rubber powered model to the right because of the nose-high climb profile.I am considering a "paper" for the upcoming NFFS Digest with some reasons/explanations for that logic..

Bob
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« Reply #20 on: November 29, 2012, 01:57:43 PM »

A friend in England was/is lefthanded and looks very awkward hand-starting an engine with that hand.   He launches both power and rubber with his right but with still some inconsistency in release attitude.

I. too, am left-handed but even so find it quite natural to launch a rubber or power model with my right and to start an engine in the more customary manner.  I guess it's a matter of degree as to how greatly an individual is affected by personal dexterity limitations.

As with Cameron Ackerley, the late Jim Brooks was totally a 'southpaw' and flew his Wakefields and Unlimiteds to the left with reverse-pitched props and 'back'ards' winding.
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« Reply #21 on: November 29, 2012, 04:54:47 PM »

"I guess it's a matter of degree as to how greatly an individual is affected by personal dexterity limitations."

I'm left-handed when I write or cut balsa. When I flew rubber I launched from my left side, though I used my right hand to wind.

I launch power model from my right side, however, but flick the prop with my left hand. I do have to concentrate to avoid bad launches.

I did at one time think about flying 'left-handed' rubber models, (as I believe Ian Davitt did/does.)
It just didn't feel natural, though.

When I played cricket at school, I batted right-handed but bowled left arm.
I gave up trying to play squash, as I could never make up my mind which hand to hold the racket with!

My father could hold a pen in each hand and then write a sentence backwards with his left and forwards with his right at the same time, producing a mirror image. If we'd lived a few centuries earlier we'd probably have been burned at the stake for withcraft!

Robin
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« Reply #22 on: November 29, 2012, 07:12:46 PM »

>as I believe Ian Davitt did/does

Yes.

As a matter of interest  (maybe)  many many moons ago when resident in Merrie Olde ...  I answered the door to a gent who introduced himself as one Dennis Davitt and said he'd like some guidance towards getting involved in buiilding a model aeroplane.........

It would seem he got the idea okay  .....
 


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« Reply #23 on: November 29, 2012, 10:08:38 PM »

Well, I'm clearly right-handed.  However, when hand starting engines, I flip with my left hand bringing my flipping finger below the engine.  Actually, a chicken stick because I don't fancy getting prop cuts from kick backs or being slow.  Even more truthfully, I use a starter motor rather than a chicken stick these days for the same reasons.

However, when flying U-Control, I hand start with the right hand so I can stand outside the circle.  Most of the time it is little Cox motors with starter springs, but I use the right hand.
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