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Seagull Boomerang or Arising Star - any difference at all?

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Robin Colbourne15/07/2020 14:35:02
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When you bank your model into a turn, some of the lift holding it up is now keeping it into the turn, so either;

  • The model will drop to gain the extra speed to generate the extra lift.
  • You feed in up elevator to keep the nose up, and the model slows down (and will eventually start to descend to maintain lift equilibrium, or stall).
  • You feed in up elevator and a bit of throttle to maintain speed and height through the turn.

When you finish the turn by levelling the wings, the model is now likely to have an excess of speed relative to when it started the turn as you now have the lift back that was resisting centripedal force; therefore the nose is going to go up. This is more apparent when turning into wind because the model covers less ground, so this climb appears steeper. When the turn is downwind and the model ends the turn going with the wind, the climb angle relative to the surrounding air is the same, but appears less steep to the pilot, as the model covers more ground.

A model with a symmetrical wing is likely to have less longitudinal dihedral(relative angle of incidence of the wing to tailplane) than one with a flat bottomed wing. It is this longitudinal dihedral which exacerbates the zoom up when the flat bottomed aerofoil model returns to wings-level flight.

Flat-bottomed wing trainers are great, partcularly for early lessons teaching older beginners in nil or light wind conditions, as the model can be trimmed to fly slowly enough that their brain processing speed can keep up, and prevents them losing confidence in the early stages.

Semi-symmetrical wing trainers are better for more windy conditions, for the reasons others have stated.

Edited By Robin Colbourne on 15/07/2020 14:37:05

Jonathan M15/07/2020 20:12:08
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Thank you Robin for your very clear explanation.

Having yesterday been gifted the very worn Boomerang for the club (which really needs a good winter overhaul first), today I drove down to my LMS (50mins) and picked up a brand new one for myself, plus a set of 2.5" wheels to cope better with our patch than the stock 2" ones. Back home, I then ran up the OS 46FX which goes beautifully! Already got a set of standard servos, etc, so hope to put it all together tomorrow, ready to fly by the weekend!

All I need (for trainees) is a suitable but inexpensive used TX for use as a buddy-box on a lead - anyone got one to sell just PM me please.

Cheers

Jon laugh

EarlyBird15/07/2020 20:16:01
204 forum posts
163 photos
Posted by EarlyBird on 15/07/2020 07:46:37:

How does the model know when it is 'turning into wind' ?

Well that is any easy question!

Obviously IT knows, because IT has Ballooned up. But that is only after starting the turn. How it knows before is beyond me.

smileysmileywinkwink 2

I am new here and there is a lot I do not understand or miss understand I thought that when one is joking that everyone would realise because of the smiley faces. This does not appear to be the case because of the serious posts that followed. Novices always blame the plane by saying IT did that. Now we all know the plane was not to blame but the one holding the sticks.

As it happens I also believe that the ballooning up is also the fault of the pilot. Either they held up elevator for too long as they came out of the turn or they did not push down elevator soon enough when the plane started to rise.

I understand that there are differences in the way planes fly and the wing section can cause ballooning up to be more pronounced or less pronounced. The issue I have is that for me none of my planes balloon up nor do any that I maiden or test fly for others. I think that is because I control it automatically as it just happens.

I conclude that all novices have to learn to control the plane at all times and with stick time this becomes automatic, we all know this.

Wind affects the plane, again as we all know, but what confuses me is that there appears to be a consensus that novices only fly in light winds. I can assure you, from personal experience, that is not the case. What I found out two years ago when I started RC was flying in a wind was more interesting. Calm conditions were in no way challenging.

And where did the idea that a trainer has to be trimmed to fly slow so that old people can have more time for their slow thought process to react come from. This infers that a trainer does not need to be slowed down for a young person. Why bring age into it at all.

So I apologise for my joke that started this discussion.

I will now step down from my soap box and be careful not to make jokes in the future.

Steve

john stones 115/07/2020 20:41:09
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Well I would suggest you carry on making jokes myself, It's just a discussion on trainers.

EarlyBird15/07/2020 21:00:54
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Thanks John.

Will do then.

Steve

David Davis15/07/2020 21:43:29
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Early Bird, I am seventy -two years of age and by no means a hot shot pilot. For example, I struggle to hold a WOT 4 inverted for more than a few seconds, but I am a club-level approved instructor with both the BMFA and its French equivalent, the FFAM and I have been told by some of my trainees that I am a good instructor, in two languages too.

I have taught people how to fly for several years and regrettably with some, I have not succeeded. All of these failures had one thing in common, most were retired when they started to learn to fly r/c models but there were some who were less than retirement age who never quite got the hang of it either. Fortunately, the majority of my trainees eventually got their A Certificates or Brevet As.

Younger trainees pick up the technique very quickly. When I lived in England my club staged a competition offering free flying tuition to three young people. The winners were all thirteen or fourteen years old. They all gained their A Certificates within three months.

Older trainees require much longer to get to that level. My latest trainee, aged sixty-four, when first given control of an electric four-channel foamy trainer had it in a spiral dive within seconds of having been given control. With trainees like him I wait for a calm day and give him a long flight on a buddy box with a Junior 60. This is a three channel vintage model which will self correct if the trainee gets into trouble, given sufficient height. Having had a successful experience on the sticks, the novice gains in self confidence and together we can make progress from that point onwards.

Older beginners also have difficulty flying in a wind. More experienced pilots look at the model and react immediately if the model is flying off course. Beginners, young and old, have to work out what's happening, then decide what to do. For older people this is a slower, less automatic process and they make lots of mistaakes before they get it right. Thank heaven for buddy boxes I say.

That's why I never take up rank beginners in a wind. The Boomerang comes into its own when your trainee has almost reached A Cerificate standard. He is able to fly the model around for fifteen or twenty minutes without a qualm and once he's got to that level, his confidence levels are high and the passing of the test will be easy.

Just my experience of course, others may have a different perspective.

john stones 115/07/2020 22:33:17
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My job when i'm teaching is to build the learner up, remove all the obstacles i can, a model zooming usually leads to a loss of speed, trainee waggling sticks coz nowts responding, it's stalling, oo'er, confidence takes a hit, doesn't want to fly in winds.

Buy the Boomerang, jobs easier, more flying days, happy trainee. wink Passed out quicker, he can fly on his own sooner. smiley

Jonathan M15/07/2020 22:35:29
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Very useful contribution David.

I too am an (informal) instructor at my club. By no means a highly experienced fixed wing power flier, I only started when I was fifty (and usually find slope and now thermal soaring more instinctive) but gradually getting better at all aspects of RC flying. One day I hope to get the B Schedule properly nailed, but for the time being I seem to be the only member close enough to the patch and with the time available to help with basic training. My main advantage in the task is that I have a lot of prior experience of teaching older adults technical and craft skills from scratch - so I'm intrinsically patient and structured.

Everyone learns differently, but the common theme (as you observe!) is that the older you are when you start, the slower the process! The essential method is to explain, demonstrate and then let the trainee practice ONE new thing at a time, building their confidence from secure basic foundations onwards.

Pilot workload has to be kept at a comfortable level at all times. This is why many otherwise very skilled fliers who aren't trained or natural teachers often wind up stressing the trainee in error - too much information too fast, or not in the right order, resulting in too little time for the trainee to settle down at any juncture and relax into comfortable level flight, etc.

Whatever a field's normal conditions of wind or turbulence (ours happens to be particularly exposed), I've become convinced that a larger traditional model like the Boomerang has an obvious advantage over the smaller, lighter foam trainers too many people buy for themselves: it can be flown a greater distance out without the trainee losing clear sight or orientation of it, which in itself buys more time for them as each leg of a circuit then takes a bit longer, allowing the trainee to settle his/her mind before the next turn or manoeuvre.

Of course the other way to start off older trainees is with a sizeable foam powered glider. This won't give any training in the take-off/landing side of things (which can be factored in later using a proper powered model), but will enable people to become comfortable with the basics of smooth flight control, orientation, etc. With this they can also spend time practicing on their own using hand-launches for any suitable field, whereas normal power training would necessitate instructor and trainee meeting up regularly at the club field while progress is slowly gained and confidence built.

Anyway, looking forward to getting the Boomerang fitted out and flying.... and maybe it'll also prove to be a suitable model for myself - alongside my electric Wot4 - to practice with for my B Cert!

Dwain Dibley.15/07/2020 22:45:13
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I have also taught people to fly with a Boomerang, both on buddy leads and in the grab the tranny mode.....

The boomerang will do anything you want. best on a .46. I have built in excess of 20 for people, and they are easy to repair. They will also fly extremely plump and overweight.

I passed my A on one , passed it on to a mate and he passed with it also. called it Tree hugger, as it ended up in one....

we got it back and wrote tree hugger on the wing, it's still flying

I still have one built from a kit, electric...Of course......

D.D.

Here she is before the tree incident.

pic_2900.jpg

EarlyBird16/07/2020 08:08:13
204 forum posts
163 photos

Thanks and wow so many Instructors!

Everything you say is true from what I have observed.

I started when I retired . I went to the LMS bought a RTF Ares Alara. Joined a club who assured me there would always be people there to give me stick time. I went full of enthusiasm to be met with a barrage of criticism many would have given up there and then. Fortunately the Instructor came 'right have you got a plane if so lets get you in the air'.

He checked it over, without comment, put me on the buddy box did the usual told me to try a few circles just to get a feel for the sticks. He landed it for me told me the rates were too low and adjusted them to maximum with the comment 'right lets see how you get on now'. Second flight he explained about circuits and flying straight and level. After he landed I asked what he thought 'you have just done in two flights what for some takes a year and others never achieve well done' he did not mention my age. Wow it felt good.

Thanks to him I passed my A in four months.

Later he had a nine year old novice who was very quick to learn, us old guys were amazed how he visibly improved with every flight. He took his A after a month and only flying at weekends amazing!.

So yes age does have an effect but when one retires one has more time to fly. It's not a competition it's just about having fun.

As for flying in a wind my instructor's response to, but its too windy surely, 'wind what wind lets get you in the air' but its 18mph are you sure 'yes you will be fine' he is very positive and never says anything negative. All his pupils learned to fly in a wind and still do. I think that on a windy day he derives some sort of pleasure from seeing his pupils flying while others are using the 'it's too windy excuse' as he puts it.

A time came when he had six novices at once so I offered to help. Never say anything negative because it sends the wrong message was the advice. I always had respect for Instructors but standing with novices, I learned, requires a high level of commitment. Having six at once unbelievable. I had two novices and had no time to fly myself. All Instructors deserve a medal in my view.

Too all Instructors thank you.

Steve

David Davis16/07/2020 09:08:57
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I tend to form a judgement as to the beginner's position on the learning curve before taking them up in a wind. I am currently teaching three beginners, two expatriate Englishmen and a Frenchman. One of the Englishmen and the Frenchman could fly in a wind but I would have to catch the model once or twice in each flight. The other Englishman has only flown once and has not reached that stage yet.

PS. I read somewhere that if the Battle of Britain Spitfire pilots had been forty years old rather than twenty years old, there would have been wrecked Spitfires all over the place at the OTUs!

Edited By David Davis on 16/07/2020 09:11:56

Jonathan M16/07/2020 20:55:40
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747 forum posts
294 photos

Nice 'tree-hugger' DD!

So here's another question: I've got the choice of either the OX Max 46FX or an Irvine 46 to put into the Boomer, both used engines but both good. Anything in it?

Dwain Dibley.16/07/2020 21:50:12
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If you look closely there is an Irvine 46 in the tree hugger, my mate swears by them. Properly set up they go every time on the first turn, and drag the model round like a rag doll.

D.D.

J D 816/07/2020 22:06:26
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1525 forum posts
84 photos

Irvine 46ARC Jupiter UK made with black carb. Has been powering my ARC Jupiter for many years. The most reliable and least fuss engine I own.

Jonathan M16/07/2020 22:14:11
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That's just like mine - except mine says JAPAN on it.

David Davis17/07/2020 08:01:52
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3785 forum posts
729 photos
Posted by Jonathan M on 16/07/2020 20:55:40:

Nice 'tree-hugger' DD!

So here's another question: I've got the choice of either the OX Max 46FX or an Irvine 46 to put into the Boomer, both used engines but both good. Anything in it?

Both are excellent engines and will suit the Boomerang admirably. I have just fitted an old Enya 50 in mine because I have a soft spot for the old thing! Your Japanese Irvine will have a silver or aluminium OS carburetter instead of the black Irvine Jetsream carburetter but that's the only difference. Most of the other i/c trainers at my club are powered by the OS 46 FX which is available for less than 100€ in France.

My Boomerang is pictured below when it was fitted with a Webra 40. Performance was adequate but the engine cut out over the field of sunflowers and I had to land out of sight.I think it needs more running in. A similar thing happened to the guy on the left a fortnight ago. A search party was organised and the guy in the middle found both models! The yellow and blue model was no worse off from its holiday in the crop!

bastille day 2020.jpg

Ben B17/07/2020 09:05:20
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1438 forum posts
4 photos

Just briefly re ballooning- it's pilot induced. On the downwind turn people hold in more elevator to prevent drifting downwind and trying to keep a constant radius on the ground (ignoring that the plane is flying through the air). When this extra elevator isn't bleed off quickly enough the plane "balloons" and people blame the plane / weather / spektrum transmitter etc etc.

 

In I.T. this is called PEBCAK

 

"Problem exists between chair and keyboard"

Edited By Ben B on 17/07/2020 09:05:46

john stones 117/07/2020 09:30:27
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They pull harder on elevator with the Boomerang as well against the wind then, no one saying It balloons ? Whether It's a bit more incidence or just the flat bottom, It balloons, It's a given pilot can correct this. Or you can choose the Boomerang.

Steve J17/07/2020 10:45:52
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"Once the aircraft has climbed out of this turbulent level it is, in effect, flying in a steadily- moving block of air. Thus, with a wind speed of 10 mph the block of air in which your aircraft is flying is moving downwind at a speed of 10 mph. So, your aircraft which flies at a speed of, say 20 mph will appear to be doing only 10 mph when flying into the wind (flying speed less wind speed) and 30 mph when flying downwind (flying speed plus wind speed). In point of fact your aircraft knows nothing about the wind speed at all and is flying at a steady 20 mph all the time!

"You will often hear people say that their aircraft tends to climb when turning into wind and dive when turning downwind. What is really happening, of course, is that they are subconsciously trying to compensate for the apparent variation in speed and themselves causing the aircraft to climb and dive."

(BMFA - Flying Start 2015)

john stones 117/07/2020 11:05:15
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Do they explain why the Boomerang wing doesn't balloon, or why the learner has this inbuilt compensation on the flat bottom wing flying ? Pretty good this learner, can't fly yet, but subconsciously is correcting for variation in speed, airfoil play no part in aircraft behaviour ?

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