Mudelismifoorum

Sai siin mõningad korrad proovitud uut mudelit Condor,kõik on väga hea,aga
Tõus on nii järsk,et peab pidevalt kõrgustüüri allapoole hoidma,muidu läheb selili.
Millised oleks sobivad miximise variandid?
Kas ehk panna mootor rohkem alla vedama?
Ise arvasin,et peaks mootorieebli mixima kokku kõrgustüüriga,st annan gaasi ja ka kõrgustüür võtab alla.

Just... gaas/kõrgustüür mix on täiesti tavaline asi ja peaks saatjal kohe eraldi valmis mixina olemas olema, ei pea vabalt programmeeritavat mixi isegi kasutama.

Ma pole plaaneriasjanduses väga kodus, aga ehk annaks ka tiiva profiili muuta klappide abil? Teine mix tekitada, mida ka gaasi kang juhib.

Mul saatja suht tagasihoidlik,miximisvõimalused on olemas,aga pan vaatama kas mingid tehasemixid ak peal on,tegemist Futaba FX6 seeria puldiga.

Allaveo korral läheb veojõu allaveo komponent kaoks ja see võib tulla päris suur (kõrguse arvelt muidugi).
Mootorlennus, suuremal lennukiirusel (planeerimisel ca 8 m/s, tõusul 10-35 m/s) peab normaalseks lennuks tiiva-stabilisaatori vaheline nurk väiksem olema ja seda see alla kõrgustüür teebki.
Miksimine on normaalne lahendus. Ka vabalennus on mootoriga ülesminejatel (F1C, F1B) mootorlennul stabilisaatori nurk automaatikaga väiksem tehtud.
Vastupidi on mootorlennukiinimestel. Nad teavad, et seisva mootoriga tuleb kõrgustüüri üles anda, et lennuk pikeesse ei läheks ja puruks ei kukuks.

Mitu protsenti reaalselt mix võiks panna,kas kusagil 10% algatuseks ja siis edasi trimmida vastavalt vajadusele.
Praegu on nii,et hoian kõrgustüüri alla ca neljandik sektorist ja tõusunurk on silma järgi kusagil 65-80 kraadi,mis oleks ka ideaalne.

Ei oska arvata. Ise paneksin algul vajalikust vähem ja siis timmimise käigus juurde.

Selge ,järelikult hakkame proovima minimaalsest ja edasi vastavalt vajdusele.

Jäta see mixi protsendi koht saatja menüüs ette, pane mõned protsendid mixi ja tõuse lendu. Kui on vähe, siis saad ju isegi ilma saatjale silmi pööramata lennu ajal näpuga näiteks 5% juurde klõpsida ja siis teed õhus uue tõusu. Nii peaks saama asja ühe lennuga enamvähem timmi.

Nii proovingi.

Mina kasutan enda elektriplaaneril nii gaasi-kõrguse kui ka gaasi-eleroni mixe, seda viimast küll suhteliselt väikese käiguga.

Ühe ja sama lüliti alla on pandud nii gaasi-eleroni mixi välja lülitamine kui eleroni-kiilu mixi sisse lülitamine. Idee peaks seisnema sirgema tõusu saavutamises samas kui plaanerdades on vaja kiiluga pööramisele kaasa aidata.

Gaas kõrguse mix toimib,vähemalt puldist sain korralikult tööle.
Homme üritan reaalselt lennus proovida.
Eleron ja kiilu mix oligi nagu tehase poolt peal,aga seadsin selle ümber mootori ja kõrgustüüri jaoks.
Uurin veel puldi võimalusi ehk saab ka selle teise versiooni paralleelselt peale tagasi,kuigi kahtlen.

Kas on keegi katsetanud ka eleronidel mingeid planeerimisrezhiime - st eleronid pisut alla,tõstejõu suurendamise eesmärgil?
Küsimus ka eleroni kiilu mixi kohta - kas kiilu anda samas (pöörde) suunas ku elerone või vastupidises,ma oma mõistusega arvasin et kiilu tuleks anda vastu.........

Hei,

jah, ma olen proovinud elerone paar kraadi alla ja üles liigutada nupu abil, aga jäi see nüüd lennuki või minu taha, aga mingit olulist vahet ma ei märganud. Võib-olla on-board logger oleks midagi aru saanud.. Mina küll soovisin saada natuke kiirust juurde vastu tuult lennuks - aga kui saingi, siis ma ei saanud sellest aru.

Mis puutub kiilu (rudder?) ja eleronide miksimisse, siis eesmärgiks on minu arust koordineeritud pööramine, ehk lennuki juhtpinnad peaksid töötama sama eesmärgi nimel (näiteks paremale pööramine). Siin on aga eleronide ja rudderi koostöö natuke tricky, sest pööramisel on imo oluline koordineerida rudder'i ja kõrgustüüri tööd, elerone kasutad pöördesse minekuks ja sealt välja tulekuks (ja kui on pikad tiivad ja väike pöörderaadius, siis jah, võimalik et pead natuke elerone vastu andma kompenseerimaks sisemise tiiva aeglasemast liikumisest tingitud tõstejõu vähenemist).

AndrusK

Rudder on pöördetüür ja on osa kiilust.

29.05 F3J Riidaja
Seal on kohal lähiümbruskonna parimad (Leedu, Soome jne) ning võib oma silmaga näha kuidas asi võistlusolukorras käib ja milline on hästi lendav lennuk.

Eleronid võiks ikka kiiluga samasse suunda pöörata. Eks see kõik oleneb muidugi ka lennukist paljuski. Minu loogika ütleb, et sirgema tiivaga võiks eleroni-kiilu mixi rohkem olla ja tugeva V-kuju puhul pigem vähem. Termikarežiimi tarvis profiili muutmine tiiva juhtpindadega on omaette teadus, mis on paljuski sõltuv tiiva profiilist, tüüride pikkusest ja laiusest ning üleüldistest mudeli eripäradest - samas katsetamine ei tuleks kindlasti kahjuks.

Suure F3J plaaneri peal jõudsin kah järeldusele, et mida vähem elerone kasutada, seda ilusam profiil peaks ju tegelikult säilima, ning seda ongi suure kaldega väikest ringi lennates vaja. Kõrgustüürga hoian kiirust ning ringi raadiust ja pöördetüür on abiks õige suuna hoidmisel ja vajadusel ka mingil määral kiiruse korrigeerimiseks.

Palju olulisem, kui termikarežiim, on minu arvates paika saada eleronide diferentsiaal.

Eleronide diferentsiaal ?
Et siis täpsemalt....

Kui palju liigub üks eleron üles rohkem kui teine eleron samal ajal alla - vast see.

Miskit sellist ma nagu arvasin ka, mul Proximal ongi nii tehtud,mingi tsehhi kutt soovitas ja andis ka suht täpsed nurgad,tal päris mitu sedasorti mudelit,saatis mulle kaks lehküljetäit erinevaid mixe,mida ise kasutab.

Ja lisaks suht normaalne ülevaade.

- Orlando Buzzards - http://www.orlandobuzzards.org -

Mixing Full House Sailplanes
Posted By Gordon On January 12, 2010 @ 10:06 pm In General Discussion | No Comments

By Rick Eckel (Copyright 1995, printed by permission)

Let’s admit it. The simple two channel ‘floater’ type sailplane are the most relaxing and enjoyable planes to fly. They look graceful in the sky, practically fly themselves, and land so slowly you can walk beside them. On a beautiful, calm, sunny, summer Sunday there is no better way to spend time than guiding a floater beneath billowy clouds suspended in a deep blue sky. But…..

There are some of us who can’t leave a good thing alone. We must have speed…… Or “performance”….. Or a thousand little switches sticking out of our transmitters. We want launches to the moon, thermal searches that cover at least three states and landings on the head of a nail every time. For us there’s no fun like the good adrenaline rush of a high speed pass low across the field!

So we opt for the full house sailplane. Fiberglass, carbon fiber, Kevlar, foam, obechi, and servos in every nook and cranny. Beasts that are inherently unstable, fast as the dickens and prone to landing like lawn darts. And then we are faced with trimming the dang things, getting them to fly in a civilized (or at least somewhat controlled) manner, and landing ‘em without cutting off our own legs. The key to all this is a computer radio and that most dreaded of all procedures:

MIXING

Many newcomers to our wonderful sport have approached me and asked about computer radios, how to choose one and what it is that you really do with one when you have it. Nosy and full of questions as they are, they are seldom satisfied with “mixing” as an answer. So here is the lowdown on what ‘real’ sailplane pilots do with a computer radio.

Let the mixing begin:
Setting up, or ‘mixing’, a full house sailplane with a computer radio can be a pretty intimidating task for the uninitiated. There seem to be so many possibilities, so many control surfaces, so many switches and so many terms and nomenclatures. Actually… there really are too many. But they’re manageable if we first understand the basics of what we need to accomplish. Then we must translate that into the terminology and control functions provided by our particular computer radio manufacturer.

Sailplanes have three distinct flight requirements:
Launching, landing and the flight task. Mixing is used to enhance the flight characteristics of the plane for each of these requirements. In launching we want to obtain the highest possible altitude. For landing we require slow speed with the most control possible in order to land very precisely. The flight task requirements vary with the task (I’m most familiar with the thermal duration task but there can also be speed and distance tasks).

As the full house sailplanes and computer radios have become more common, basic ways of enhancing each of these flight requirements have become more or less standard. They are enabled by mixing two or more control functions (for instance: flaps and elevator or aileron and rudder) together so that the flight characteristics of the plane are optimized for a particular flight requirement. The interesting part is that each airplane design will have its own reaction to the typical mixes and must be optimized individually for top performance.

A Few Definitions
Camber, reflex, crow and butterfly are terms tossed about by those baptized in the use of computer radios as if their meaning were obvious. From my experience they are only obvious if you already know them. (Or is that obvious?)

Anyway, a brief review won’t hurt. Camber and reflex are kind of equal but opposite terms. They refer to the position of the wing’s flaps and/or ailerons. Camber means that the flap or ailerons are deflected a little downward effectively adding under-camber to the normal wing airfoil. Adding under-camber means that the bottom surface of the wing becomes more concave. Reflex, on the other hand, is deflection of the flaps or ailerons upward. Moving the flap or ailerons up removes camber in the airfoil making the bottom more flat or even giving the wing a ‘reflexed’ trailing edge.

Butterfly and crow are different terms for the same thing. A sailplane in the crow or butterfly configuration has its flaps lowered and both ailerons reflexed (raised). The ailerons stick up and the flaps hang down making the plane look reminiscent of a crow or butterfly as they approach a landing.



The flaps, ailerons or the full trailing edge (both flaps and ailerons) can be referred to as cambered or reflexed. Camber and reflex are used in a variety of circumstances. Crow (or butterfly) is only used for landing or perhaps for diving out of a thermal.

Launch Mixing
A sailplane will launch from a winch or high start perfectly well without any trim adjustments — assuming that the tow hook is well positioned. However the launch may be enhanced by several adjustments. The first is to camber flaps a bit to generate more lift during the launch. A little up or down elevator compensation is frequently of benefit when flaps are used during launch. Flaps only cover perhaps 1/2 of the length of the trailing edge of the wing. Some fliers find that additional lift can be generated and a steeper launch attained if the ailerons are also cambered to match the flaps, or a little less, when launching. As a beginning point of reference, we are talking about a cambering of flaps and ailerons of perhaps 1/4”.

At the end of the launch some additional altitude can be gained by “zooming” off of the winch line. This zooming can be enhanced by reducing airfoil drag by reflexing the trailing edge. That is, reflexing both the flaps and ailerons slightly above their normal positions, Again, as a point of reference, we are talking about maybe a 1/16” reflex of flaps and ailerons.

All of these things can often be controlled using the 3 position flaps switch as the master channel for the flaps and slaving the other channels that require adjustment (elevator and ailerons) to them. This means that a lot of flexibility for mixing to flaps is necessary for the launching task. That makes it one of the key things to look for if you are choosing a radio for a full house sailplane.

Landing Mixing
For landing a sailplane the flaps are again important.They are useful for obtaining the slow speeds while retaining good control that make spot landings easier. Most airplanes exhibit a nose up pitching motion (or “ballooning ) when flaps are deployed. So a mix of elevator to the flaps is employed to counteract the pitching. The elevator mix used in the launch may or may not work (or be available) for the landing flaps deployment. So a different elevator mix may be needed. Most pilots also prefer to have landing flaps fully proportional and controlled by the throttle stick on the transmitter so that they can vary the flaps depending on their landing approach.

Another enhancement to the landing function is the use of ailerons as spoilers. When both ailerons are reflexed and the flaps are lowered the plane is said to be in the “crow” or “butterfly” configuration. A little reflex of the ailerons just dumps (spoils) the lift of the wing and steepens the glide slope. A large degree of reflex adds drag as well. So this landing mix is a lot like the launch mix except that the ailerons have a different motion, the elevator to flaps mix is different and the flaps are proportionally controlled by the throttle stick rather than having preset positions via the 3 position switch. Only the more advanced programmable radios and/or those specialized for sailplanes will have the ability to provide both launching and landing mix setups.

Flight Task Mixes
Perhaps the most widely used flight task mix is rudder to ailerons. The purpose of this mix is to allow coordinated turns to be accomplished using only the right stick on the transmitter. This mix also eases the transition from a two channel (rudder—elevator) sailplane to an aileron equipped model. (Just don’t forget that the ratchet trim for the rudder is now under the left stick!)

There are also a variety of other mixes for the flight task requirements for sailplanes. Pilots tend to vary in their preferences for these mixes. Part of the preference is personal and part is because different planes respond differently. Some pilots like to have the trailing edge of the wing camber, either just flaps or flaps and ailerons, with the application of up elevator. This gives an apparent increase in the effectiveness of the elevator. Conversely they sometimes want the trailing edge to reflex with the application of down elevator. This makes the plane accelerate more quickly. Pi!ots like to be able to switch this mix in and out depending on whether they’re in a thermal or not. So they turn it on and off with a switch on the transmitter.

In addition to or in place of the above,some pilots like to be able to ‘dial in’ some camber on the wing while they are working a thermal. With more camber some airfoils can fly slower, develop more lift, and get more altitude out of a given thermal. Once a thermal expires or is lost, pilots want to ‘flee the sink’. The ability to reflex the trailing edge can be very effective when you need to get away from a particular piece of sky quickly. These controls are often handled by a pot (potentiometer) on the transmitter or, as an alternate by the throttle stick so that they are proportionally variable. In slope racing it is very important to make good ‘bank and yank’ turns. I understand that some pilots like to use an inverse aileron differential mix in order to put some adverse yaw in the plane as they bank up for the turn just prior to the ‘yank’.

The Mix is the Secret!
There are many other mixes and variations on mixes that different pilots use for different flight requirements. I think that some of them must be closely guarded secrets! Secret mixes that provide a competitive edge that pilots develop and hand down only with greatest ceremony to select co-conspirators! I think that’s why I can’t fly as well as Brian Agnew or Joe Wurts (or a lot of other pilots for that matter) — I don’t have any secret mixes! (Aren’t conspiracy theories wonderful excuses!)

Article printed from Orlando Buzzards: http://www.orlandobuzzards.org

URL to article: http://www.orlandobuzzards.org/?page_id=892

Click here to print.

Copyright © 2009 Orlando Buzzards. All rights reserved.

Veel üks artiklike algajatele.

The Model

Before flying the model you should check it out to be sure that there are no warps or mis-aligned surfaces. A model with a twisted wing, or one where the tail is not perpendicular to the wings will be much harder to trim than a "straight" model. Similarly, check the lateral balance, one heavier wing is not uncommon. At low speed these problems are not so evident, but at high speed they can be very pronounced and require a different trim to correct them. Make every effort to have a "straight" model .
The whole purpose of the trimming process is to make your glider easy to fly in a "hands off" situation. The easier it is to fly, the better it will fly .

First launches

Having checked the model for warps etc, put the CG where the manufacturer suggests (or having done your own calculations) checked that the controls all move in the correct direction, you are ready for that first launch. The object of the first few launches is to obtain a neutral trim setting for ailerons, elevator and rudder. Fly the model into wind and adjust the trims to obtain straight and level flight. Adjust the elevator trim to the point where the model feels "soft" or "mushy" and then go forward about 2 clicks of down trim .

Centre of Gravity

This subject is probably the object of more debate than any other with regard to model gliders. Why, because changes to CG can drastically affect the way your glider flies. There is no single "perfect" CG for any model, your flying style is part of the equation. The following technique is widely used and will get the CG close to your ideal position .
Launch the model, level off after the zoom and head into wind. Dive the model at about 300 with wings level for about 2 seconds. Then release the elevator stick and carefully observe the behavior of your model. If the model pitches up (climbs) then the model is nose heavy. Land the model, remove some nose weight (5-7g). Push in 2 clicks of down trim and then launch the model again. Fly straight and level into the wind and adjust the elevator trim to be just forward of that "mushy" point. Now perform the dive test again and observe the pitching motion of the model. If you remove too much weight the model will continue to dive at ever increasing downwards angles. In this situation the elevator may not respond quickly so don't perform the test close to the ground. (If the model will not pull out with up elevator, don't panic, just feed in some aileron input and the model should come out of the dive. If all else fails push in full down elevator and perform a bunt or 1 outside loop.) The aim is to achieve a model which does not pitch up or down when you release the elevator stick. i.e. is neutrally stable in pitch. (If the surfaces are all straight it should already be neutrally stable in roll and yaw)

Control Surface Deflection

Elevator:

Moving the CG rearwards makes the elevator control more efficient or effective. That means that less movement is required to obtain a given amount of pitch movement (the stick becomes more sensitive) The cure for this is not to add lead to the nose of the glider, but to reduce the amount of travel you have on the elevator. Assuming that you are using a computer radio it is a simple matter to reduce the travel (dual rates or travel adjust). How much elevator movement do you need? The 2 situations that require the most elevator movement are the down elevator at the top of the zoom after launch and the amount of up elevator in a tight, slow thermal turn. Reduce your elevator movement so that the stick is almost bottomed out in that tight thermal turn. If you are using equal throws for up and down elevator, test the amount on launch. If you find that you need more throw at the top of the zoom then dial in some more and consider dialing in some exponential as well. A softer elevator input makes the glider much easier to fly, especially at greater distances .

Ailerons:

The roll rate of your model is not affected by CG, but increases with the speed of the model. This should be born in mind if you are setting up flight modes in your Tx. So how much aileron control do you need? This is a bit of a "feel" thing, but for mind the most demanding situation is the downwind turn onto base leg when setting up a landing. If you have done everything correctly you will have plenty of speed on and it is not difficult but we have all made that turn too low and too slow at some stage and felt the sluggish response of the model. Set the aileron rates such that you are happy with the response whilst flying slowly downwind and see what it is like in all other situations. A well trimmed thermal glider should not be able to perform 3 rolls per second, one roll may take up to 2 seconds to complete. Any faster roll rate than this may get you in trouble when you are thermalling a kilometre downwind at low altitude. Minor inputs on the sticks should result in minor outputs at the model. Don't forget that you have exponential control options in your Tx. Aileron differential can have a large bearing on how flat your model will perform thermal turns. All model gliders require some aileron differential. 8 units up and 5 units down is a good starting point for most gliders. Aileron differential is best tested in calm neutral air, strong thermal activity can mask a poor set-up. Launch the model then switch off the aileron-rudder mix. Roll the model to the left and closely watch the angle of the fuselage to the horizon. If it goes nose high (yawing to the right) you have too much differential. If it goes nose down (yawing to the left) you have too little differential. Make the necessary adjustments on your Tx and test again. Aileron - rudder mixing does not cure the nose high or low situation described above, changing the differential is the only cure. Aileron - rudder mixing is used to stop the model skidding in the turns. Imagine looking down on your model (plan view) as it performs the perfect thermal turn. In an ideal world the fuselage would follow the perimeter of that circle. If it is nose in or out there is an increase in drag that will reduce the rate of climb. This is not an easy thing to observe from the ground so using some well proven settings is about as good as you can do. On a 3 metre, 2200g, RG15 equipped model try 10-15% mixing percentage. The faster the model flies use less mixing, the slower it flies use more .

Rudder:

The rudder control is not used independently in a thermal glider a lot. As described above it is mixed in automatically in conjunction with the aileron most of the time. Exceptions to this are on launch where corrections to launch direction should be made with rudder not aileron. If you have flight modes then set up a lot of rudder travel in "Launch" mode. The other consideration is rudder differential in V tail models. This should be tested in calm neutral air. Launch the model and fly into wind with your normal trim settings. Feed in full left rudder and observe the angle of the fuselage to the horizon. Ideally it will remain horizontal as the fuselages yaws to the left. Test with right rudder. If you have the same movement for both left and right rudder then the fuselage should do the same to each direction. If it climbs then you need to reduce the amount of movement on the upgoing side or increase the movement on the downgoing side. This will require some programming input on your part and depending on the brand of radio you use may not be easy. Look in the travel adjust section for rudder to begin with. If the nose drops then the correction is the reverse of that described above .

Flaps:

On a modern 6 channel glider the flaps serve 3 purposes. On launch they are used to raise the CL of the wing. In thermal mode the whole of the trailing edge can be raised or lowered to decrease or increase the camber of the wing. This will increase or lower the flying speed of the model. On landing the flaps are lowered to increase the drag and reduce the lift that the wing creates to increase the rate of sink .
Launch. This is a complete and complex subject in itself. Suffice it to say that about 200 positive (down) deflection is a good starting point .
Thermal. The complete trailing edge can be lowered about 3mm (on a 3 metre 250mm root chord wing) to enable the model to fly slower in small weak thermals. This should be set on a switch function rather than a slider if possible so that you always get the same deflection and can easily return the trailing edge to a neutral setting. Similarly the complete trailing edge can be raised 2-3mm to improve penetration in strong winds, between thermals or for speed tasks. The ideal settings vary from model to model and should be tested carefully. Again, calm, neutral air is ideal .
Landing. To really slow the model down and increase the rate of sink, the flaps should be lowered at least 600. At the same time it is normal practice to raise the ailerons about 300. Ideally, this braking action (commonly called crow or butterfly braking) should be operated by the throttle stick. The ideal settings will be determined by a number of things, how much downwards flap movement is mechanically available on your model, what mixing is available on your brand of Tx, and your flying style. There are however, some basic rules to follow .
It is better to drop the flaps than raise the ailerons (it effectively washes out the tips lowering the stall speed)
Dropping the flaps will cause an upwards pitching movement which should be corrected with down elevator mixing. Have lots of practice landings to fine tune the amount of down elevator mixing. Once properly set up landings become a breeze.
Raising the ailerons will reduce the roll rate of the model, making directional changes on final slower than you might expect. If you have flight mode switching on your Tx then dial in as much rudder as you can in landing mode
Remember that the "crow" action is proportional. Half stick movement should result in half the rate of descent etc. Raising the flaps quickly may result in the model losing airspeed and "dropping" out of the sky. Try and move the throttle stick in a smooth and controlled manner .

Towhook position

With few exceptions the towhook should be placed in front of the CG. If your model has an adjustable towhook then start about 6mm in front of the CG with the initial launches. Chances are that you have moved the CG rearwards during the trimming process and once you have completed all the steps above you can move the hook back. The ideal position also depends on flap and elevator presets so there is no definitive position but suffice it to say that if the trailing edge of the towhook is 2mm in front of the CG the model will launch well. Moving the hook rearwards increase the steepness of the climb, but ultimately with a reduction in directional stability. Go too far back, get a poor release of the model and before you know it your pride and joy is buried 300mm deep in the ground. Tread warily as the towhook approaches a position near the CG!

üks lingike http://www.lakesawyerhawks.org/how_to.htm