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Author Topic: Trimming and flying a hlg - Kevin Moseley - wrote some years ago  (Read 2694 times)
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Kev
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« on: February 21, 2012, 03:24:34 AM »

Trimming and flying a hand launch glider – a basic and beginners guide
by Kevin Moseley

First and foremost, I am by no means a master at what I have done or do in hlg or the class. I am fortunate enough to have been encouraged through my parents and step father to fly the class as I have always had a “good arm”. By good arm, I know I can throw and throw very hard, however, all that throwing to extremes has taught me a vital lesson, its not how hard you throw, its all in technique and strength only has a little to do with the launch. It almost as if I have finally learnt that by not throwing so hard and backing off, I throw smarter and more controlled. So, it’s not down to power, its down to technique and a well trimmed airplane. However, its getting to that stage of having a well trimmed model that we need to get to and by offering various scenarios in this text, I hope to reproduce the problems that can be found and how to resolve them all.

– the expressions used and understanding them.
I would say that the main thing about the airplane and trimming is that you are going to be putting warps into the wood, bending this way, that way, using expressions such as wash in, out, finger tabs, rudder etc. It helps if we have an idea about what these do so when they are used in the examples, you understand better.

First – wash in. Imagine a sheet of wood that is flat. There is the leading edge and the trailing edge. If we want the sheet of wood to rise on one side when the wood is in flight, then we would bend the trailing edge down at certain points. Look at a full size airplane, if it wants to get more lift at slower speeds, then its flaps are dropped to give that added airfoil shape. With the wind underneath this, it effectively pushes up that wing. This is the same with gliders. In order to make a wing lift, as hlgs have a flat bottom on the wing, one bends the trailing edge down.

Wash out. Ok, so you want to make the wing be pushed down, so the same in reverse applies. Wash out is when the trailing edge is bent upwards and therefore, the air going over the top forces the wing down. Easy huh!

However, if you watch a full size airplane turn, or even these radio models, they have ailerons and you can make an airplane turn by increasing the amount of wash in and out it has. If you are flying straight and level and want the airplane to turn right – you turn the control stick right and away she slides. However, to achieve this, the right wing must drop down and the left wing up. Referring to the thought process above – the right wing would not need that much lift and needs forcing down, so the ailerons go up (wash out) and the left wing needs forcing up, so the flap goes down (wash in). To stop the turn, the pilot would resume back to straight and level flight with no wash in or out on either wing.

So, by understanding this, wash in and out can have the effect of being able to turn an airplane as well as making it more stable as we shall see later. If you can understand this part, the rest is simplicity itself. As a lot of what we do involves wash in and out, its really quite easy from here onwards. However – moving on – heres a drawing of a sideways view of a glider.

Its important to visualize that the wing sits on a length of wood we call the pylon. There is the fin at the back and another flying surface called the tail plane or stab (short for stabilizer which will become apparent why later).

In order for this airplane to fly, it needs the wing, fin, stab and a fuselage (fuz). On a lot of the modern airplanes, the part that separates that stab and wing is called the tail boom. Its just a word that means that its something that separates the wing and the stab. If you did not have a stab and fin and just threw the wing and fuselage, the model would dive to the ground and go no place – hence why the tail plane is there and is known as the stabilizer. Its job is to assist the stabilization of the airplane in flight. The fin provides a means of turning the aircraft in slow flight and is covered later.
However, by having all these parts on an aircraft, we get a long way to achieving safe flight.

Centre of gravity ( c of g).

Imagine a sheet of wood and you hold it between your two hands and resting at opposite ends on your finger tips. As you move the fingers closer and closer, eventually they will join and you will have found the centre. The weight is even on both sides and should be the middle of it. If one finger was removed, one side would be heavier and therefore, your other index finger would need to find the centre again and move slightly to balance it. This is the centre of gravity or c of g. Our gliders need a c of g about 70 % from the leading edge of the wing. So if you have a wing that is 100 ml wide – then at 70ml, that’s where the c of g would be. This figure can and does change model to model –design to design – however, I have always said approximately 2/3 of the width of the wing and you are onto a winner. If the model has a c of g too far forward, one thing it will do is dive.

If we refer again to the drawing of the glider sideways on – as it flies, it glides through the air smoothly and all being well, does not dive (points the nose at the ground and hits it). So, what causes a model to dive and how can we correct it?

Diving – why?

Fact 1 – the model is lightweight and made of wood. It wants to glide. Fact 2 – the ground is hard, unforgiving and has no consideration to you wanting to keep your model in the air. So, we need to stop a dive.

A diving airplane is not a good sign that things are well, entirely the opposite. What causes it. First, it could be down to balance or the location of the c of g (centre of gravity). I mentioned earlier that the glider needs a c of g at approximately 70 per cent or two thirds. If you were to add nose weight – ie putty to the nose of your glider, you would make the nose heavier. Therefore, if you were to find the c of g again, it would mean that this would have moved forward. It may now be at 50 per cent or half way across the wing. This is not good. The airplane is nose heavy and needs adjusting, so lets keep the c of g at the correct point and if its diving and the weight is wrong – then it needs checking.

Assuming the c of g is correct – excellent. However, there are other factors that contribute to making an airplane dive. The word incidence is one that comes to mind immediately and one I have learnt a lot about through my trails and broken airplanes.

Incidence – definition, the angle the wing is against that of the stab. If the wing is flat along the pylon and not down at the front and up at the back, or vice versa, then great. However, if you were to draw a line from the underside of the wing along the plan, then drew a line for the top of the stab, it should all be straight – no stab pointing up at the front, down or any other direction. Its easier to draw it than explain it so see below.

If you look at your airplane and the wing at the leading edge is in some way down a little – even 1/64 – anything other than perfectly flat – it has to be cut and glued again. I don’t mind a little what is called positive incidence – its often very helpful but the maximum should be 1/16 leading edge higher than the trailing edge.
Assuming you have it lower at the leading edge, as the model attempts to glide, the airflow is pushing the wing down and as I said before, the ground tends to not take any prisoners, so get it so its perfectly flat – or just a little “up” at the front and reglue. I will stress here that no amount of throwing it is going to do any good, it wont change, you will hurt your arm and it needs changing desperately.

Still diving? No problem…
Lets look at the line that we drew from under the wing. Assuming that the front end under the wing is perfect, excellent, what about the back? In a perfect world, you need a nice straight imagery line. However, what if the stab is down at the back? Well, the first thing this is going to make the model want to do is point its nose down. The wind under the wing is great and is helping it fly, but if the stab is down, we are effectively, forcing the back end up, pushing the nose down and in she goes. So lets keep that wing and stab flat in a line and no variations will do. Nice line, no problems. Now do a few test glides and a few throws, nothing strenuous mind you.

Ok, its gliding, but now when I throw it, it dives and keeps turning until it hits the ground.

It still dives huh?? Its one thing after another isn’t it? Hlgs are all about small corrections making a large impact on an airplane. How many times have we heard it when we were learning to drive, small corrections, not huge turns of the wheel It’s the same here.

Ok, we have eliminated the c of g, there is a flat line between underside of wing and so all is good. Take the model in your hand and launch it flat from about head height. Does it glide away in a nice left gentle turn? This needs to be a large floating glide? Is it a small sharp turn? Too sharp? Not good.. Time to look at the fin and the part known as the rudder. A rudder helps turn the airplane at slower speeds. Looking at the fin – is it perfectly straight? If not, take it off and get a new one on. No ~ shapes will do here – it has to be straight. At the part where the rudder is though to be, you need to bend that last few mm to the left. You don’t need the whole rudder bent and it only needs very tiny movement. Wet the balsa with your siliva, then bend gently and breathe it dry. Even breath the turn in, the moisture from your breath is adequate for this. Once dry, again, try the glide, if everything is now correct, the balance, incidence etc, the glide should be floaty and away from you. One of the possible problems of a spiral dive is that the rudder is over powering the turn and as the model tightens its turn in a thermal, it becomes terminal and down she comes. So, reducing the amount of turn will help this.
So, a small amount of rudder – max 1/16 is great, no more needed and by now, you should not be diving anymore.

So take the model to the field and start throwing it. First – nice straight pushes – just to the left of the wind. If the model is balanced correctly and she glides in a nice left turn – then, time to take it up a step and start launching steeper and steeper. There is one more possible reason that the airplane can dive now assuming there are no warps in the stab and that’s the angle that the model is launched at. If you launch the model vertical, unfortunately, this means that the nose is pointing upwards. As speed lowers, the model will stall and then start a dive down. If you don’t have enough height, the model will drop its nose and head towards the ground. You need to lessen the angle of the climb a lot – this way the model will climb out right in a large right turn and then as the speed is bled off, the airplane levels out and she glides smoothly away and into a left turn.

Finally - Altering things on the tail plane – well, the next option would be to add a little “up” on the tail plane. By up I mean wash out. This is sometimes needed on models and is a great help for small adjustments. This is just a case of wetting the tail plane right next to where it joins the fuz and bending it a little upwards. Not too much and bear in mind that by doing this, you are altering the incidence a little and therefore, the nose may need a little plasticine again to add a little weight.

That I believe covers diving – so lets cover the turn a little more.

Turning
These gliders need to climb in a right turn and then glide left. Why? Well, if you throw right and have right rudder, the model is going fast away from you and with the extra right rudder, it makes the whole thing terminal. The extra turn off the rudder will force the model right and into the ground. However, I will stress that this can be controlled somewhat to a degree with warps – but not advisable. Lets keep the airplane safe and do it right left.
So, to turn it, breathe in a maximum of 1/16 turn at the end of the fin. This needs to be done from the base of the fin end to the top. Again, very small movements pay dividends with these airplanes. Too much and the ground takes no prisoners. Too little, the model will not turn into the thermal as quick and the walks are long collecting them. So, just a tiny movement.

One of my best suggestions to help with a rudder is to change the angle that the grain of the wood is. In my models, I have the grain of 2/3 of the fin at about 45 degrees to the fuz. Then, I change the rudder and do it the opposite way. Its meant that the rudder has stayed in the correct angle and also has stayed warp free. If you have the whole fin vertical, sooner or later, it will snake and then you need to replace it.

The other way of being able to turn the model is to mount the fin at the correct angle and skew it – personally, I don’t do it at all and would not recommend it. If you need to change things, its not easy on these gliders at all and therefore, keep it straight and correct things gradually.

Launch

One of the main problems that folks have is that they get the launch wrong and things go wrong in this. The model flies out of their hand in a large left turn and its perfect. Then they come to throw it and its all wrong.

The perfect launch – run, pull glider back, throw to just right of wind, model climbs, right wing down, speed bleeds off, transition, then left turn. No loss of height – so what happens when it don’t work this way.

Problem - Model climbs too flat and gains little height.
Not throwing steep enough – increase angle of launch

Problem – on climb – model starts going straight instead of climb right
The rudder is counteracting the throw – too much left rudder. Decrease it.

Problem - The model rolls fully on the climb to the right
The airplane has a warp on the right side of the stab – wash out, decrease it. Also, add a small amount and that’s very small wash in the opposite side on the stab.

Problem - Model loops
Too much incidence, if you do not have an adjustment screw, then where the stab joins the fuz, bend this down.

Problem – model climbs straight up and then turns left.
Not enough right bank – increase bank on launch.

Problem – model climbs straight up and then stalls. Often terminal!
Increase the bank, if it stalls, then add a small amount of left turn. Add a small amount of weight.

Also, remember, to launch to the right of the wind. Left is a no no!

Problem - Model dives to the right on climb
Too much right bank on throw, add a little wash out to the left wing tip to help push it down on climb.

Ok. So there are flat stabs and there are V tail stabs and these need slightly different trimming. My chosen model for many years was Mick Page ‘s Butterfly 2. This man is a real gent and one of the nicest hlg fliers I have ever had the pleasure to meet. Hes not the tallest on the field, but hes the one with the biggest heart.
For months and years I flew against him and watched him. Hes smaller as I say, however, he picks air like no one I know. Max after max. My throws were all over the place and I watched in awe at this man winning.
Eventually, on a thing that I aint gonna learn if I don’t ask, I went and sought his advice. He became one of my idols that day and is still a real great bloke.

Butterfly has a V tail. In other words – its not flat as what we talked about. This model needs trimming slightly different as the dihedral at the centre of the stab makes things a bit more lively. Basically, build the model as per the plan (it still wins these days) and then go from these directions which I plaugurised from his article.

Launch problems with a V tail.

Problem – model barrel rolls to the left, comes out of the transition very fast and then spiral sin.
Solution – reduce left rudder. Wash out right hand tip of the stab also increase wash out on right side of the wing. More right bank on launch.

Problem – model rolls on climb to the left entering a very tight circle. Great idea for catching the thermals but real bad in the wind.
Solution – this time add a little wash in on the left hand inner part of the stab – near the fuz. That’s the best place.

Problem – model performs a vertical loop – Runnnnnn as it follows you and panic!
Solution – reduce left rudder, add down on left hand side inner panel of stab, increase wash out on right wing tip and more right bank.
Stop running and panic for another reason instead
Model turns and loops to the right, however, finishes nose up and drops in and usually after a 90 degree turn.
More wash out to the right side of the right wing tip, take off some left rudder, little more negative incidence to the stab.

Problem – as above but model pulls out from dive too quick.
Solution – reduce left rudder, more wash out on right wing tip, more bank on launch.

Problem – as above but model completes a minimum of 180 degrees – ie a banked loop
Solution - more left rudder, reduce right wash out on right side of stab, less bank in launch
________________________________________

So that’s all there is to it or so I am told. Its all through many years of flying the classes that I can now write a bit about them and give something back and what I hope is of use to you.

My flying continues, albeit restricted in hlg. The old shoulder is not what it used to be anymore- and I ain’t as young as some of you but I can be found at the big events, often watching if not flying a little so do come and say hello. I assure you I don’t bite and will happily try and help you as much as I can and share some air with you if you want.

If not on the field, then you will find me with the other gliders I fly, however, these ones I cant throw that well – not just yet but I will not be beaten…!!!!

All the best,
Kev
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Kev
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« Reply #1 on: November 01, 2012, 07:07:14 PM »

Just out of interest, when did I write this?  Anyone any ideas???

Kev
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Dave Andreski
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« Reply #2 on: November 01, 2012, 07:12:04 PM »

Don't know when you wrote it Kev but I've had it on my computer since April, '06.
Dave
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Kev
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« Reply #3 on: November 01, 2012, 07:23:32 PM »

Oh hell Dave, that makes me feel old  Sad   Was written then around 2004!  Came across the article and had forgotten about it.  Was wrote initially for the SFA when its original owner (lovely chap who has since passed on) was running it.  Then I had a disagreement with his son and I had it removed or so I thought and brought it over to here.  Nice to see its still around, even if I have long since stopped flying the class due to age and illness.  Still flying full size though and love to be in the sky alone with 18 meter wing slightly above and behind me as I ride along the air currents and float with the birds with the vario pipping away!   Cheesy
How you doing these days?
My best wishes
Kev
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Dave Andreski
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« Reply #4 on: November 01, 2012, 07:32:08 PM »

Kev,
SFA is where I got it. I think Lyman Hatz converted it to a WORD DOC. That's the version I have.
How am I doin'? How about 60 pounds overweight and feeling every bit of it. I'm gonna try to shed most of it before Spring. Huge task but I gotta do it. My 'get up and go' seems to have 'got up and went'.
Good to see you back here.
Dave
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« Reply #5 on: November 01, 2012, 07:41:12 PM »

Kevin:

You also put together an excellent piece for the 2003 National Free Flight Symposium.  Not as much trimming info, but some really good building tips and, best of all, what to do at the contest.

Louis

That Sympo is out of print, but check with NFFS Publications at www.freeflight.org. Used copies are sometimes available. 
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« Reply #6 on: November 01, 2012, 07:49:16 PM »

I know the feeling Dave. Iv kidney problems and waiting for a date to remove a disc in the old back. Was play silly beggars years ago diving in the Maldives and slipped two discs.  At 39 I had the start of a heart episode (dad had had his attack the previous year and I just had to copy) and been declining since this last four years. I lost a couple stone by making sure I went for a walk every day. Half killed me but got even more fascinated with plants and birds and a ten min speed march became a walk to see what else I could see and it became an hour.
I'm not working at the moment, so spending a lot of time walking, photography and on that face book thing where I created one for vapour trails / Contrails.
Have my passion though for free flight and always will spend my days looking up, then others strapped with a glider on
My back looking down above an airfield hoping not to get wiped out or hit an F1c going past me!!
Start walking - 54 days till Xmas - you could lose a stone in that. If you do it - I will!!
Off to. Sleep now.
Night mate.
K
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« Reply #7 on: November 01, 2012, 07:58:20 PM »

Louis - was it 2003!!!! Oh my lord. I will still have my copy of that somewhere.
I was feeling old thanks to Dave. Now I feel ancient. My son was 4 then! A lot has changed and I have even less hair than my father Jim Moseley - although he has a 19 feet comb over that is used instead of streamers at contests. They stand him on some steps and his comb over gives good lift indication.  If kill to get my razor on his head and shave it off. Bald is great and dad will have to use a streamer like everyone else!!
Have a good evening
K
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« Reply #8 on: November 01, 2012, 08:54:30 PM »

Hi Kev, I left you a message via SEN re Stafford's F1C that you were interested in.   Did you get it?  Or start it?  It's a pretty good base balsa model to get into F1C or Power IMHO.

Re. losing weight.  I'm not heavy at 73/74 KG......Well I don't think so, but a couple of months ago I was over 75KG so did not have a beer or a wine or a coffee for a full month and dropped to 71.5KG.
Back on it now in moderation and walking about 45 minutes every day and steady at 73+.  Have our FF Nats coming up in January so wish to be in reasonable condition.

Cheers.
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« Reply #9 on: November 01, 2012, 09:24:24 PM »

Good to hear from you Kevin. You contributed so much to HLG. Everyone misses your contributions.
Here's my favorite photo of you and Christopher from 2003.
I'm sure he's a fine young man now and hope he has continued the modelling tradition of his father and grandfather.
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Re: Trimming and flying a hlg - Kevin Moseley - wrote some years ago
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Me with F1B - epic retrieval (flew 10km after DT)


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« Reply #10 on: November 01, 2012, 10:25:08 PM »

Hi All,
Don't wanna evangelize or anything but I recently shifted from being a died in the wool carnivore to being a semi vegan (not militant, but I avoid anything related to animals especially dairy of any kind and eggs etc.). I eat lots of whole foods (meaning not refined ... so no white flour or sugar based products). I did this to ensure that I do not come down with the nutrition related "western diseases" that killed my father and Uncle. The result has be awesome. I don't really miss meat and dairy and have seen the pounds melt off. I am now about 30 pounds lighter after 2 months and looking forward to getting back the my youthful fighting weight of ~190 pounds (I am 6'5"). I do exercise (walking the dog and rock climbing) but nothing more than what I have done for years.

If you really want to turn back the clock on heart disease and a variety of other western disease symptoms get this book and be amazed: The China Study by T Campbell. More people should know what this book reveals. If you take it seriously you will shift to a plant based diet and never look back.

ok my two cents ... live long and prosper.
BG

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« Reply #11 on: November 01, 2012, 11:23:47 PM »

BG,

This is the second time today that I've come across this book, so I just ordered it from Amazon.  Thank you for your post.

-Kang
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« Reply #12 on: November 01, 2012, 11:43:37 PM »

To each his own of course, but I've never eaten much meat of any sort even since a child.  Can't remember the last time we had meat here. It just does not appeal.

 We are not a crazy vegetarians as such......We have booked a very nice place to take the family out for Christmas lunch and I'm sure to have a slice or two of turkey breast. (Royal Pines Resort Benowa.)

 We do eat lots of veg. and fruit, and my Wife is a fantastic cook to boot, as are our two girls and our Son.  Had a tremendous mix of very spicy veg. last night for dinner.  Not sure what's on tonight.
Only dairy would be that flat white coffee in the morning from our machine or great local coffee shop that I really do enjoy.  Maybe a very light scrapping of butter on toast, wholegrain of course, in the mornings.

Will I live to 100?.......No way, just hopefully stay reasonably fit and well until I drop.
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« Reply #13 on: November 02, 2012, 01:06:59 AM »

> or a coffee for a full month

A month?  A MONTH Huh

 Shocked

I NEED 3-4 mugs of strong black unsweetened a day just to get by !

That first one of a morning is SOooooo  good!
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« Reply #14 on: November 02, 2012, 06:38:47 AM »

> or a coffee for a full month

A month?  A MONTH Huh

 Shocked

I NEED 3-4 mugs of strong black unsweetened a day just to get by !

That first one of a morning is SOooooo  good!

Yeah, I understand exactly.   But I could see my belly expanding and decided to do something positive about it.....It was tough, but it partly worked.  I'm sure it's the milk in mine as I enjoy it is the problem.

That China Study book has some interest to me.  Going to our local library in the morning, and after a VERY good coffee at our favorite spot, will see if they have it.
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