Low tech thermal soaring - RES?

[StraightEdge]

I'm interested in getting (even building if I really have to?) a 2-3m rudder/elevator/spoiler flat field glider for bungee launched pure enjoyment, rather than an expensive full-house mount with powered winch gear for contest work or a fashionable electric launch thermal soarer.

I know its a retrograde step, but are there any good designs still available in the UK or from Euroland, either ARTF with modern materials or more traditional kits?

The only current option I've found so far is the Circle Dancer (based on the Drela Bubble Dancer) from Hyperflight. Not cheap, but at least it looks good-to-go and I'll only need three servos!

Would also need to source suitable bungee, line, reel, etc.

Any help/advice/pointers/prejudices would be most welcome.

Jon

[Gary B]

Hi Jon,

 You're looking at the 100S (100 inch span/2.5 metres) class, there is an active competition scene.

At competition level the glider mostly used is the 'Tracker', British made all composite.

Kits that should still be available are the Cambrian Elan and Flair Albatross, both quick builds and good flyers.

Chris Foss Centi-Phase can be built from plans, an old design but good.

All are RES, apart from the Elan which has no spoilers.

If you could make it to Bicester on  a Thursday evening I could show you all four and let you have a fly.

 Cheers

   Gary

Edited June 9, 2015 by Gary B

[Gary B]

I missed the West Wings Lancer, no experience of this apart from it's a relatively expensive kit and from reviews likes to fly on the fast side.

GB

Edited June 9, 2015 by Gary B

[Gary B]

Electric but avoids the bungee is the Parkzone Radian, very popular at our club.

[StraightEdge]

Gary

Super advice thanks, and I'd like to take up your offer to join you at Bicester (about an hour from here depending on traffic). PM with time, location, etc - and whether or not the current windy weather will be too much this Thursday!

So far I've flown some slope and 1m mosquito class DLG, but my dicky ankle is beginning to make proper 1.5m discus launches a bit painful...!

Jon

[Gary B]

Will the wind ever drop?!

If you can drive 12 miles further to Brackley I could show you these models and current F3J/F5J ones as well.

I'm usually free Monday to Thursday.

GB

[StraightEdge]

That would be grand!  Google shows 47mins in current traffic... which reminds me that its waaay past my nod time and I've got the school run first thing!

Touch base tomorrow.

Jon

[Gary B]

Sure, no worries.

 

[Ribs]

Hi Jon,

I built an Allegro-lite, similar to the Bubble dancer, only not quite as big (2m span). It's absolutely awesome! It is solid as a rock on the bungee and is designed for a full winch launch, if you make the spar correctly.

I highly recommend having a go at this - all the parts are available and there is loads of on-line information about the build.

If you want to get flying sooner, then go with what the 100s fellow suggest - perhaps a tracker - but for an easy to fly, top performance RES model, you can't go wrong with the Mark Drela designs. If you don't have time to build something (the AL does take a bit of patience) then I'm quite sure the Circle Dancer from Hyperflight will be fantastic.

If you'd like more info about the Allegro build, let me know.

cheers,

Chris

[heli_bee]

Jon,

I have had great times with my old 100" Algebra. Mine has a fibreglass fuselage and built up wings. However, the plan is still available for r the 3m version with wooden fuselage.

Martin

[StraightEdge]

Pete

Most interested - PM sent

Jon

[StraightEdge]

Hi Jon,

I built an Allegro-lite, similar to the Bubble dancer, only not quite as big (2m span). It's absolutely awesome! It is solid as a rock on the bungee and is designed for a full winch launch, if you make the spar correctly.

I highly recommend having a go at this - all the parts are available and there is loads of on-line information about the build.

If you want to get flying sooner, then go with what the 100s fellow suggest - perhaps a tracker - but for an easy to fly, top performance RES model, you can't go wrong with the Mark Drela designs. If you don't have time to build something (the AL does take a bit of patience) then I'm quite sure the Circle Dancer from Hyperflight will be fantastic.

If you'd like more info about the Allegro build, let me know.

cheers,

Chris

​Chris

This is valuable input, thanks.

I'm attracted to the simplicity, stability and visibility of a large polyhedral ship.  Although I 'wasted' my early teenage years by building rubber-powered scale from kits and plans, I've come back as a middle-aged person who has only been RC flying for a couple of years (like learning to drive when you're fifty!) and into thermal soaring for but a year now (like learning to read the road and struggling to anticipate the flow of traffic for the first time at such an age and with less than keen eyesight!).  So I'm inclined to something that can be flown with minimal input, especially at a distance, whilst I concentrate on what the air is doing, and where and which way my glider is pointing within it.

That's not to say I mightn't eventually graduate to a more modern F3J ship and the contest classes that predominate for these here, but for now my instinct is towards the simpler 'aesthetic' of the Bubble Dancer, Allegro, etc.

I'm also short of time to engage in a building project (self-employed, single-Dad, that sort of thing), so my ration is for flying.

I might yet speak to Neil at Hyperflight about the Circle Dancer 3000... but also hope to pick up Pete's Algebra 100s as a second mount.

Cheers

Jon

Edited June 12, 2015 by StraightEdge

[Ribs]

Those teenage years with rubber power models are never wasted!

I had exactly the same ambitions as you a year or so ago when I started the Allegro build - I wanted something to move on from DLG to a bungee/winch capable model to work on my thermal searching abilities. There's loads of models that will be good for this, but I am a little biased now toward the Mark Drela designs - he's a engineer I find very inspiring, so it felt like embracing a bit of history to build the AL. 

If you are short on time, the Allegro build may not be for you, as the construction takes some effort, particularly the carbon capped spar with its kevlar wrap and the fiddly little tip joiners. I think it is great now that the Circle Dancer is available, as this means the model type is an option without putting in months of build time. I think the construction of the Circle Dancer is perhaps less involved than the original Bubble Dancer plan - no kevlar wrapping I suspect and no tapered carbon spar caps (which, as for the Allegro, you have to order in from the USA). If you're not planning on full winch launches, this won't matter.

One thing going for the more modern models (build yourself or "ARTF") is that they will benefit from advances in both aerodynamics and materials research. The AG aerofoils and others have been developed specifically for thermal flying by model sailplanes. Many of these sections are possible only because of the readiness of carbon fibre and kevlar that has occurred in recent years, along with improved manufacturing techniques for mouldings and so on. These developments allow for bending and torsional stiffness without the need for a deep spar or large d-box.

No doubt at all that the older models, such as Algebra, will be good, but things have moved on a little in the years since these models were designed. Add to this the fact that so many models are coming out of Eastern Europe and China to a very high standard, means that exotic materials and complex construction need not cost the earth - just look at the work involved in, say, the Circle dancer or the Skymaster (other sailplane vendors are availlable ;-)) and they start to look very cheap at the price. If I factor in my time to build my Allegro, I stagger to think what it stands me in at!

Whatever you go for, I wish you lots of luck and fun with it. I find flying off the bungee or into a light slope upcurrent the most relaxing of flying. I time my first flight and then set a countdown timer to a duration a minute or so longer than this and spend the rest of the evening/afternoon, trying to make it to that time. It's good to know others out there are still looking for this kind of aeromodelling fix.

all the best,

Ribs

[Ribs]

Totally fair points Pete.

I guess what I was getting at is that RES models or non-moulded molded models may be perceived as low-tech, when in fact they are simply optimised for a different kind of flying and may have received as much 'tech' advancements as the bigger, more complex ships. 

Yes, you are right, there is a big jump between a second hand Algebra and the £500 (for the airframe only, not forget) Dancer.

I agree that, in general you get what you pay for too, the point I was making is that even £500, though clearly a lot of money, is getting you an awful lot of airframe. I think we live in an unprecedented age in aeromodelling, where the range of models and equipment available is staggering and at a quality and price that is amazing.

Anyway, to topic, perhaps the best plan for Straightedge is to get a good cheapo second hand model to start with, then save/build/procure as suits.

Right then, I'm off to Westbury where there's a light Northerly to play with...

cheers,

Ribs (Chris Lamming WSRFC)

[timboiow]

Late to the party again, but for what it is worth...have you seen the plans of the Philip Kolb Miles 2M?...looks like this would make a good low cost ship ,easy to transport, quick to rig and reasonable performance. Might also be a candidate for a scale up to 100" just to make it easier on the aging eyeballs. I think the plans were on the rcgroups forum as pdf so should easy to find (if not I did grab a copy so shout if you'd like hem emailed through).

There was also the 100" version of the multiphase that Chris Foss did, although that was a foam wing I believe, but it wouldn't be hard to sketch up a build up wing for it (use the fendon wing as the basis - scaled down of course)

Hope this helps

Timbo

[StraightEdge]

Well folks, Pete very kindly sorted me his old fully-loaded moulded-fuselage Algebra (with two pairs of extra wing blanks, one with ailerons for later maybe, also a tailplane and spare balsa fuselage), a Spektrum carbon-friendly RX, plus a bungee and line on reel, all for a completely fair quantity of beer tokens.

The main question now (in order to get the old bird in the air) is what control throws on rudder and elevator... Pete?

And a secondary question (less urgent):  I've never used solarfilm or similar coverings, so what is the method of removing old covering and applying new?

Cheers

Jon

[Jef Ott]

Educated guess time (take better note if anyone has model specific data)...

Rudder throw on most (RES) models is 30 degrees either side of central. No point in going for a greater deflection than this as the control surface will probably stall. 

Elevator will require about half an inch (10-13mm) movement either side of neutral.

Good luck with removing the old film - defo not my forte!

Jef

 

[satinet]

If it were my money i would go for a skybench aerotech (usa) or hoellien model (germany) for a built up model. 

 

The reason moulded models are expensive is because they take ages to build (man hours). Carbon, fibre glass etc aren't that high tech or expensive in this day and age.  Moulds and materials are a cost but If i was going to charge you a normal working rate for building you a 3m woodie to a top notch standard it would be a lot of money as well.

 

The problem with wooden models is that no one wants to pay what they cost to make which is why there is not a lot of choice. It's not profitable i think. 

Edited July 12, 2015 by satinet

[Gary B]

Apologies to Pete for not mentioning the Algebra in my non-exhaustive, biased list of 100 inchers!

I remember a friend cursing trying to fit servos to an EMP Algebra fuselage, ship in a bottle stuff!

I would go for as much throw as you can get without servo binding and use a good amount of softening exponential around neutral, test glide from a hand throw, wiggle the sticks and see what you think.

Solarfilm is a pain to remove cleanly but it can be done with patience. Brown parcel tape can be used to remove remnants but it can lift fibres from the wing veneer.

GB

 

[StraightEdge]

Thanks for the advice on throws.  I set the Algebra up more or less as Jeff and Gary suggested (and Pete also suggested on the phone before I saw these posts) and went out for some very basic javelin trimming flights in yesterday's unusefully-high winds.  I then moved on to try out the standard bungee system of 25m of surgical cord (the first 5m needed to be discarded due to UV degradation/brittleness) plus 100m of fishing line, which I also picked up from Peter, but which was a little long for my local field, and so had to position my launch position from down a rutted byway leading off the main field!  A tricky, but more or less successful series of test flights despite the overstrong and turbulent conditions, and came away with one unhurt middle-aged Algebra.

Compared to the almost instantaneous turning responsiveness of my Elf 1m mini-DLG also just on rudder and elevator, I found the much larger size, thicker airfoil section and polyhedral wing of the Algebra much slower to respond to turns, and - frankly - need to carry out plenty more launches on days with more moderate winds and more favourable thermic conditions before I get used to it.

Re the bungee launch system:  what sort of launch heights can one expect from 25m of surgical tubing and 100m of line?  If I reduced both these components by say 25% each to fit my local field more comfortably, should I expect a launch height reduction of 25% (ie a linear reduction) or would it be poorer than this?  Also, might I more sensibly just reduce the length of line, whilst keeping the surgical tubing at almost full length?

Cheers

Jon