Altered title - Can a low wing model be a good trainer?

[Toni Ertl]

with the model in a balanced, banked turn the 'gravity' it experiences isn't directly downwards, it is on a line through the vertical plane of the fuselage.

With the model (or full sized) plane in a banked turn the centripetal force a plane experiences will be on a vertical line through the fuselage. Gravity will continue to act in the same direction it always has - effectively a true vertical - and will create a pendulum effect in direct proportion to its strength in relation to the centripetal force the airframe is experiencing. Thus if the plane is pulling 5G in a turn the 'pendulum effect' will be around 20% as strong as if the plane were not turning at all at the same angle of bank. This is why the pendulum effect is significant for low speed FF models and relatively irrelevant for most RC stuff.

The earlier part of this thread reminded me of my first 'trainer' - a Flair Cub. That would absolutely hammer round the patch, and although it was supposed to fly on a 25, it didn't really want to know without a 40. It wasn't until I built a DB designed trainer with a PAW15 that I found out what a trainer was supposed to be like.

[Tony Jones]

Toni

Note I put gravity inside quotation marks in my previous post. I don't think Alisdair would agree with you but I'm not knowledgeable enough to put up a reasoned argument in his defense.

Best wishes
Tony

[Tony Jones]

Thinks: If pendulum effect exists in a balanced turn, then as bank angle is increased and the point at which the vertical component of the wing's lift gets displaced further and further away from the CG of the airframe towards the inside of the turn, one would need more and more aileron to resist it. In a vertically banked turn, the righting moment trying to roll the aircraft back upright would be enormous and one would have to hold lots of 'pro turn'aileron to overcome it - would you not? But this is not what we experience in practice.

Best wishes
Tony

[Peter Miller]

Rereading kermode I think he was referring to a slideslip which you would not get in a balanced turn,
Mechanics of Flight is virtually the same as Flight without Formulae but has masses of maths in it which I am afraid are way over the top of my head.
I also have a superb book called "The Design of the Aeroplane" by Darrol Stinton. It covers everything you ever need to know and more, Most of it is way over my head again but I do pick odd bits out of it plus some interesting annecdotes..
Alasdair reccommended it to me and I bought a copy S/H, cost a fortune.

[Toni Ertl]

Toni - I don't think that the pendulum effect is all *that* great, especially at steeper angles of bank as the centre of mass will have reduced leverage in relation to the centre of lift. In fact at steeper angles of bank you'll require less aileron input to get the same roll rate rather than more.

Try this: Take a highwing airframe and arrange a 'pivot' at the centre point of the wings (near enough to the centre of lift with the mass of the fuselage hanging below). Tilt the wings at roughly 30 degrees. Release the wings you're holding up and watch how quickly the wings move to horizontal. Then try it at 70 degrees, then at 90 degrees. With the wing vertical it will almost teeter before accelerating toward horizontal.

This is consistent with what you experience in RL. Past a certain point (probably around 45 degrees, but not exactly) the 'pendulum effect' will actually decrease. It can't ever disappear as no-one can turn off gravity, but it can become so small as to be insignificant in an unmanned model.

[scott cuppello]

All this aerodynamic stuff is great [not being sarcastic!], BUT, speaking as someone who can still remember what trainers fly like....I have often wondered why the only thing reccomended is high wingers?

The reason I'm saying this is that yep, on a flat calm day, they are stable, easy to fly and land...but throw some wind into the equation, and they are more difficult to land than most...either wanting to stall, or glide by....I can understand that in one respect this is a good thing [if potentially expensive if it goes pear shaped] for beginers, but it's also very frustrating. Trying to land high wingers in wind nearly destroyed my confidence at one point!

[Peter Miller]

I ahve seen several modellers who just could not master landings, they always seemed to get mixed up in the last few yards and crash. This included the modern high wing trainer.
I usually gave them a few flights on a vintage style model in calm weather. That sorted them out and they never looked back.
I had one person who had a Sid Miller (no relation)) Rhoma. A 50s single channel R/C model high wing auto stable model. He had three channels in it. He never crashed once and we didn't have buddy box in those days.

[Bob Cotsford]

"I had one person who had a Sid Miller (no relation)) Rhoma. A 50s single channel R/C model high wing auto stable model. He had three channels in it. He never crashed once and we didn't have buddy box in those days.
Send to friend"
I had a Rhoma when I was about 15, ED Hunter deisel and home made cingle chanel radio -flew itinto the school craft block. The models in those days were pretty much guided free flight, not so much radio control as radio interference. The whole learning curve was much more gentle.

[Pat (rActive) Harbord]

Still, interesting point that we think Cessna like and not Piper like. I have to agree (with someone) that low wingers fly in a more predicable way, especialy on finals. Tending to go where pointed. It's not how I learnt to fly RC because I build and fly small free flight stuff, so naturaly went the high wing route, but I'm sure a 1st low winger/aileron trainer is probably the better way to learn for most people if built light and flies slowly. I have a good friend that learnt on a Wot4 which has quite an interesting configuration, and am sure this is a contributing factor to his confidence and ability to fly "anything"

[arthur bishop]

Wow! what a great thread! that lot put the hawk among the pigeons..? or is it pidgeons?,by the way,consider birds,(yes, lets) are they not shoulder wing?

[Tony Jones]

Arthur
I always have trouble with pidgeons/pigeons too. Spellcheck has just underlined pidgeons in red, so I suppose it must be pigeons.
I suppose birds are shoulder wing because of the necessary muscles. So should we assume that after millions of years they are still learning? ;)
Best wishes
Tony

[Peter Miller]

I know how to spell pigeon but only because I fly an Easy Pigeon.

[arthur bishop]

Sheesh! 'Lo lads,good typical club house stuff! high wing versus low wing, it has been argued in the past,it will always be argued,it keeps the aeronautical stew pot bubbling, fly a 'high winger' by the seat of your pants,then fly a 'low winger' at 77 I no longer fly anything,but,there is a different 'feel' about it, 'hanging under' or 'sitting on', yes or no? it's a good discussion.

[Peter Miller]

When I learned to fly R/C in about 75 everyone was scared of having to fly their first low wing model. We got really good with the high wing models first.
When I flew mine, a Cambria Instructor, I suddenly wondered what all the fuss was about it was so easy but orientation was still took some getting used to.

[Tony Jones]

Sorry Arthur, it's not a question of 'hanging under' or 'sitting on' - however intuitive that appears. It would be if the aeroplane was stationary, but it is flying through the air, so complex aerodynamic forces are what primarily determine stability.

My personal opinion is irrelevant; what matters are the scientific 'facts' established by far brighter and more knowledgeable people than me.

Of course, the best scientists acknowledge that 'facts' are nothing more that 'what we understand to be the case at present'. So we proceed on that basis until something comes along to modify that view. So if God one day puts in a personal global appearance, the scientists will say: 'Ah, this new evidence leads us to modify our view of the universe and all that and everything. Great.'

Oops! I sense a drift off topic...

Best wishes
Tony

[Myron Beaumont]

Carry on ! Very interesting !Angels seem to be pictured with loads of dihedral .I wonder why ?

[arthur bishop]

Tony,thank you, I value reminders of things that are,and will not change,you inadvertently mentioned God,dont apologise,
He is the great aero dynamicist,why do we hang under a parachute and not stand on a platform? now I have really diverted..... who is on tea duty by the way? oh yes,has anyone got an Owlet plan?

[Tony Jones]

Arthur
Do I detect an ironic or even sarcastic tone here? :0 Dont forget that us 'Low Whingers' have accepted pendulum stability at the instant of roll but say that if the aircraft has yaw stability, it will translate immediatey into a roughly balanced turn, thus cancelling out the pendulum effect.

Parachutes don't operate with any forward airspeed so pendulum stability is all they've got.

I've done a bit of hang gliding and am just ruminating on how one would launch a low winger.

Best wishes
Tony

[Toni Ertl]

Angels seem to be pictured with loads of dihedral .I wonder why ?

It's because they must remain upright at all times.

;-)

[Tony Jones]

I was told that Angels have that much dihedral because they aren't actually very good fliers.

[Myron Beaumont]

Who told you that ?

[Myron Beaumont]

Tony
I wouldn't dream of flying a LOW wing hang glider (which more or less proves something & i'm not sure what !)
Mine was a Sunspot after the Regallo i'd built. Yes I know I'm going back a few years .

[Tony Jones]

Myron

God. Said he just couldn't get the right sort of recruit these days. More interested in being celebs than in practicing circuits and bumps.

My point about the low wing hang glider was intended to show that the choice of a high wing isn't always due to stability: other aspects can affect it. Like the need for a good downward view, or in this case, ease of launching and attachment of pilot.
Best wishes
Tony

[arthur bishop]

Tony,no Bro,I'm not being sarky,I have much respect for fellow Modellers, but you say 'chutes have no forward speed,ha! well if you are drifting towards a steeple or old fashioned chimney stack...a pull down on right or left then forward you go..hopefully,whilst still descending of course, sorry, I have digressed from the discussion which is good because I am learning anew. from what I remember an aircraft can be made to perform any shape if it is unstable enough,but parasol wing seems to give more stability,yes?

[arthur bishop]

Brian,What wing span is your "Eurobat"? it sounds quite a 'biggy',