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Seagull Boomerang or Arising Star - any difference at all?


Jonathan M
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Looking to buy a traditional trainer for club use with a buddy-box, and have a spare OS46 to go into it.

Is there any practical difference between the Boomerang and the Arising Star (2" bigger span), or are they in effect exactly the same thing? Are they equally robust? Different wing section? Any real difference at all?

Boomerang:

Span – 61ins
Area – 612 sq.ins
Suits – 40-46 2-stroke
Approx flying weight – 5.7-6.1lb
Section – Semi-symmetrical

Arising Star:

Approx flying weight - 5-6lb
Suits - 40-46 2-stroke
Area - 645 sq.ins
Span - 63ins

Alternatively, anything else that is still made that'll fit the bill?

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Cheers.

Just to say its not for me to learn on, but to use with the buddy-lead to introduce potential new fliers and to train beginners etc.

Our club field is exposed, usually with a bit of slope lift/sink on two of the four sides and can be a bit turbulent due to trees upwind - so the usual modern lightweight foam trainers don't really help novices gain early stick-time or confidence.

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The Boomerang is my favourite ARTF trainer. It can be flown in a stiff breeze without ballooning when turning into wind. There are lots of beginners in my club and I do a fair bit of instructing. I've just maidened a Boomerang this afternoon. It was powered by an old Webra 40 fitted with an MDS silencer. It was alright but I think I'll fit my Enya 50. I've flown that combination in the past very successfully. Which engine will you be using?

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Thanks for the steer, especially the point about the Boomerang being the better option in breezy conditions.

DD, I've got a used OS Max 46FX and I was going to buy a new trainer for it - hence my question earlier - but I've just now been gifted by another member for club use a very knackered-looking Boomerang MkII complete with an Irvine 40 !!

It is restorable as a winter job, but frankly its potentially quicker (and less irritating hassle than trying to do a never-ending series of quick fixes) to put together a new one for the rest of this summer, and install whichever of the two engines runs the most reliably and is better suited for the purpose.

Boomerang.jpg

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Never mind what the model knows or otherwise, what will two almost identical trainer models with moderate dihedral do differently as they are turned into the wind, everything else being equal? Will the one with a flat-bottomed wing section balloon up more than the one with the semi-symmetrical wing section?

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The flat bottomed wing will gain height more readily into wind

Where the semi symmetrical wing will penetrate more easily without gaining height from the wind

Big advantage with landing, the flat bottomed wing

Can be flown more slowly for arrival

But in the UK, I think the Boomerang can be flown on more days considering wind speeds

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Posted by Steve J on 15/07/2020 09:02:31:
Posted by Jonathan M on 15/07/2020 08:52:31:

Never mind what the model knows or otherwise, what will two almost identical trainer models with moderate dihedral do differently as they are turned into the wind, everything else being equal?

Assuming that the model is high enough that wind gradient effect are negligible, the model doesn't know if it is being turned into or out of wind. 'ballooning' is down to the actions or perceptions of person on the sticks.

That may well be the case, I bow to the greater aeronautical knowlege of those who state that there is no such thing as ballooning into wind. However, to my way of thinking if a model is travelling downwind and then turns into wind the lift should increase if the model has a Clark Y aerofoil because the airspeed over the wing has increased. I.e models' speed plus speed of the wind produces more lift, that's why we take off into wind isn't it?  If it's all in my imagination I'm happy to live with that.

The Boomerang still remains my favourite ARTF trainer espaeciallly if the weather's a bit breezy. Telemaster 40s are nice flyers too but you have to build those and they DO have flat bottomed wing sections!

Edited By David Davis on 15/07/2020 09:14:46

Edited By David Davis on 15/07/2020 09:17:07

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We all know that any airframe is unaware of it's ground speed whether it is flying downwind or into the wind, however subjectively some of my planes appear to want to zoom as they turn into the wind and some are blissfully unaware of their ground speed when turning back into the wind. Having learned to fly models on the slope I was taught to push in a brief touch of down to offset my Impala's tendency to zoom a little when straightening up out of a turn, my electric Junior 60 for example, does exactly this (both sport flat bottomed airfoils), yet almost anything I've flown with a symmetrical/semi-symmetrical airfoil ( seem ! ) not to  🤔 .

Edited By Mr Chinnery on 15/07/2020 10:43:08

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I've trained newbies on both and also the Irvine Tutor 40 (I & II). By far the best was the Tutor 40 but a very, very close 2nd was the Boomerang. Tutor 40 is no longer available so it's the Boomerang, which incidently I used for my B test.

With the CG set correctly (that is, not nose heavy) it has a plenty long enough glide for landing and as has already been stated is better suited to windy conditions.

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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

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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

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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

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