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BUNGEES (HI-STARTS)

 ADVANCED ARTICLE

UNPOWERED GLIDING FROM THE FIELD

Why gliders?

They are the most user friendly and least expensive way to enter radio control flying. They are also what many choose to stick with because of their special challenges, quietness and closeness to nature. Further, there is no noise, no messy fuels and they are not subject to council "noise limitations" imposed on internal combustion engined planes.

One of the attractions of the great outdoors is excercise, and fetching bungees will give you exercise.

Gliders launched from the field are also suitable for the slope.

Flight Times (See also Catching Thermals article)

This will depend on the conditions, the thermals and your ability to stay in them. Expect 2-12 minutes for your average flight, sometimes many more!

A Word of Caution:

A fast moving glider can be a lethal object. Gliders must be flown safely and responsibly in a safe area. They are not suitable to be flown by children without an experienced supervisor.

What glider for the beginner?

Recommended Size: 1.8 metre (6 foot) to 2 metre wing span

  • Big enough to: - carry the weight of the required radio equipment; - be seen and in control at 300 feet up; - fly slowly enough to be stable in the air and be gentle to land.
  • Small enough to: - fly in a good range of winds; - be easy to build; - be transported and stored. At the very least, it should have a wing span of 6 feet.

A plane under 6 feet will usually fly too fast (with shorter flights) and/or require lighter (more expensive) radio equipment and will be difficult to read its reaction to thermals. A plane bigger than 2 to 2.5 metres will generally have difficulty in higher winds, needs more strength in its construction and not be as manoeuvrable as a beginner generally requires.

Wing shape:

Polyhedral - that is, the wing is "bent" about half way out and (usually) also in the middle. (By the way, if you are in a quandary as to whether the additional bend in the middle of a polyhedral wing is essential, don't worry about it - both usually fly well.)

Gliders with polyhedral wings are controlled with rudder and elevator only, are particularly stable and respond better to the controls than a conventional looking plane which has a single bend in the middle.

Planes with ailerons (control surfaces on the wings) usually require more vigilance and concentration to keep them level, whereas a well trimmed polyhedral glider will be self-levelling.

Construction:

Balsa-wood is easy to work with and repair. Avoid fuselages and wings covered in fibreglass at this early stage, they are generally a little too heavy for the beginner and/or when crashed, far more difficult to repair.

Fuselage Construction:

Balsa-wood, possibly with light plywood, covered with heat-shrink covering.

Wing Construction:

Balsa-wood, covered with heat-shrink covering. Foam and Balsa-wood is an alternative. A wing that can dismantle is preferred for transport and storage.

Build From Scratch, Buy a Kit, Buy Almost Ready to Cover (ARC) or Almost Read to Fly (ARF)? -

Buying your own balsa and building from a plan won't save much money, so first time around let the kit builders do much of the work for you. Expect to pay A$70 to $95 for a kit and expect to take some 40 hours to build it.

In addition to the kit, you will require Covering, Glue and probably control rods and horns which go on the Control Services (Rudder and Elevator - down the back of the plane), and a special iron for applying the covering. (See How to Build your plane and install your Gear.)

Your shop may be able to do you a complete deal on all the bits but I do recommend strongly that, as a raw beginner, you do not stray from the size, weight and wing shape suggested in this article.

Planes can also be bought partially assembled and Almost Ready to Cover (ARC), requiring some more minor assembly, gluing and then covering. Expect to add roughly A$100 for this luxury.

The next step up is Almost Ready to Fly (ARF) which will be ready covered and require a small amount of assembly and then installation of radio equipment. These planes are more expensive again and can also be heavier. This is important, especially for the beginner, as the heavier they are, the faster they fly and the harder they fall - and break(!).

A plane of 6 feet to 2 metres will be more forgiving if it is below 900 grams. Suitable beginners kits in this size and weight include the Prelude Plus (by Southern Sail Planes), 2 x 6, Brolga, Quiet Advancer, Easy Answer, Isis and the Gentle Lady.

The 2.5 metre unpowered Albatros is also an excellent glider in light conditions, but is not suited for higher winds.

For detail on ARF polyhedral glider kits, see your hobby shop but watch that weight!! Avoid anything over 900 grams.

In fairness to these kits, they will generally have been built "straight" (ie without any warping) but still have them checked by your expert assistant before putting them into the air.

Spoilers

Spoilers are usually a pair of small strips of about 300mm (12 inches) that are embedded in the centre of the wing and can be raised to reduce the lift being provided by the wing.

A dedicated chanel is required to operate them so this means they cannot be used with a two channel radio.

They are used to stop gliders rising too far in a thermal (big thermals can eat planes!) and if required to bring the plane down for a landing, particularly if trying to land on a spot, within a time limit, or simply because the landing approach was too high to land without them.

They can be particularly handy when landing at the slope when the landing area is small or the lift simply won't put your plane down.

They are "nice to have" but unusual on a 2 metre floater. On some larger planes in some conditions / locations they are very valuable.

What Radio? (also see the What Radio to Buy article)

Most trainers require a simple two channel set which will cost around A$120. For this you will get a transmitter and, to go in your plane, a receiver, battery holder, on/off switch and two standard size servos. (Servos are the small boxes with levers on the top which transform electrical impulses from the receiver into a mechanical motion.)

There are many popular brands in this price range, speak with your local hobby shops and people who own sets for more information.

The next step up is a multi-channel radio (generally four or more channels) for some A$300 plus (plus plus). More advanced gliders (with multi control surfaces) and anything motorised will require more than 2 channels. However many advanced pilots still retain their two channel set as they are suitable for a number of other planes including hand launch gliders (HLG), flying wings and slope soarers. Thus two channel is still a good start - and very good value if you consider all the bits that come with it .

Batteries (also see Batteries & Chargers article)

Two channel transmitters almost always use AA size dry cells. Duracells and Energizers are suitable but some generic brands are half the cost and just as good.

You will need 8 cells for the transmitter and 4 for the receiver.

Down the track you may wish to purchase rechargeable batteries, but be aware that these are more expensive initially, can run down quicker and generally require an overnight charge unless you own a fast-charge 'peak detector' unit. Nicad batteries are getting cheaper and are now available in capacities of up to around 1100 milliamp-hours.

In the plane, you will generally require 4 cells. (5 cell packs are sometimes used in high performance gliders running lots of servos.) A two channel set will have generally come with a 4 cell battery holder. A multi-channel set is more likely to have come with a sealed 4 cell pack of rechargable cells.

Check your plane's remaining battery capacity regularly with a battery testing unit such as made by Hitec (about A$45 - cheap insurance against losing your plane!!) or, my preference, an on-board battery indicator - with a line of LEDs - about $25.

Always have a supply of Duracells or Energizers (or generic alkaline cells) with you in case you run out of battery on the field.

Getting Training and Guidance (also see Learning to Fly article)

You WILL need to be trained if you want your plane to last more than 4 seconds.

There are many model aero clubs around with members willing to assist you. For details of these speak to your local hobby shop and other fliers. It is important to note that some clubs specialise in Internal Combustion powered planes and may not have the emphasis that you require on gliding.

Location requirements: Plenty of space for stretching bungee, few trees to tangle bungee line or crash plane into.

At a club, you will require a separate space from power fliers. Some clubs may prohibit gliders (totally or on "power flying" days) because of the lines interfering with the power models and the need for unpowered gliders to have "right of way" when landing because they have no ability to stay up while another plane lands.

 

Great Planes Spirit.

SPECIFICATIONS
Wingspan:
78.5 in (2000 mm)
Wing Area: 676 sq in (44 dm2)
Weight: 30 oz (850 g)
Wing Loading: 6.5 oz/sq ft (20 g/dm2)
Fuselage Length: 39.25 in (1000 mm)
Requires: 2-3 channel radio & 2+ rolls of covering

 

 

 

Gentle Lady

 

All that glitters is not gold! This plane looked great but sank quickly.

Hitec Ranger - basic popular 2 channel radio

Hitec Flash 5 computer radio.

5 channels, 5 model memories (earlier models had 2), mixes.

Approximate cost: - from around A$400 including radio; plus club fees.

Item

Approx Cost A$

Your cost $

Radio - 2 channel OR

120

 

Radio - Multi Channel

300-800

 

Dry Cell batteries - 12 (for most 2 channel sets)

12

 

*Glider Kit

90-140

 

*Covering

20-30

 

*Glue - CA

10

 

*Knife

5

 

*Covering Iron

45-50

 

Battery Tester

45

 

Shop Bought Bungee OR

150-200

 

Do it yourself bungee (rubber bands & line)

30-40

 

Certification of radio

25

 

Frequency key

3

 

Club Fees, including Insurance

75-200

 

Total

$

  An Almost Ready to Fly (ARF) kit may be around - A$200 - A$350 excluding radio. Replaces items marked * above, but knife, covering, iron and glue may eventually be required for repairs.

How to get your glider into the air

You have possibly seen gliders launched by rubber "bungee". These consist of about 30 metres of surgical rubber tubing with one end of the rubber is attached to the ground with a tent peg, or similar. The other end is attached to 100 - 125 metres of fishing line, usually about 25 kilogram/50 pounds breaking strain, with a parachute on the far end.

(Two and a half 500 gram bags (A$4 each) of number 64 rubber bands from your bulk office supply shop, looped together in threes, plus some key rings, the fishing line and a bright scarf may be a cheaper start.) The ring on the parachute (or scarf) is attached to a simple hook on the bottom of the plane (usually about 25 - 30 degrees ahead of Centre of Gravity).

The plane is pulled back umpteen metres to put strain on the line then launched by the experienced pilot into the wild blue yonder(!).

 

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