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### From Theory?

A better understanding and the basis to learn more quickly.

Concepts, Figures and Explanations

- Primarily concerned with understanding the detail of how a balloon goes up and down.
- Some surprising facts and reasons why.
- Some practical stuff.
- Understanding the principles allows you to work it out for yourself.

Equilibrium Temp

- What is ET at take-off for a 77,000 with an all up weight of about half a metric tonne and ambient temperature of 16 °C ?
- Stand-up temperature approx. 40°C (200 Kg)
- Maximum envelope temperature is ???

77,000, 519 Kg: 86°C

- Exact conditions
- All up weight: 519 Kg
- Temperature: 16 °C
- Altitude: 120 ft (ground amsl)
- Lift is 10 grammes (0.01 Kg)
- From Liftcalc/MiniSim (website)

- Warmer & Heavier
- Temp 23 °C, AUW: 564, ET = 105 °C

Net Forces, 86°C, 86.5°C

- Equilibrium Temperature
- neutral buoyancy

- Half a degree increase
- small net force upwards

False Lift

Aerodyamic effect of a curved surface

Net Forces, 86°C, 86.5°C

- Equilibrium Temperature
- neutral buoyancy

- Half a degree increase
- small net force upwards

- Take care
- need to overcome inertia

* Ascent rates which will be maintained.

If you know the envelope temperature can you predict what the balloon will do?

Ascent RatesHeating: 77,000 Cu ft

- Rule of Thumb
1 second of burning increases average envelope temperature by 1 °C

Cooling: 77,000 Cu ft

- Rule of Thumb
10 seconds of not burning decreases average envelope temperature by 1 °C

Staying at Equilibrium Flying straight and level

- How often do you burn?
- This is replacing heat due to cooling.
- What affects this frequency?
- Differentiate between those things that give you a higher equilibrium temp. at take- off
- and those that affect heat input or loss.

Normal Response Times

- Attaining but without haste.
- From neutral to 100 fpm up
- 10 seconds (2 second burn)

- From neutral to 100 fpm down
- 30 seconds (cooling)

- From 300 fpm down to zero
- 40 seconds (6 seconds of burner)

- From neutral to ascent of 500 fpm
- 50 seconds (16 seconds of burner)

Emergency Response Times

- Achieved by leaving burner full on, attaining and exceeding the target
- From 100 fpm down to 100 fpm up
- 10 seconds

- From 200 fpm up to 200 fpm down
- 20 second (two 5 second dumps)

- From 300 fpm down to 300 fpm up
- 25 seconds

- From 500 fpm down to 500 fpm up
- 32 seconds

What have you learnt?

- Temperature control !!
- Short burns

- Fast ascents – overheat.
- Fast ascents if very high – more overheat.
- Now we’ll look at what happens during a descent.

Slowing a Descentby increasing envelope temperature

Equilib T Reached

Exceeded

Temp Up

Downward force

Deceleration rate increases

Descent rate

Above ET slows more quickly

- Foot off the accelerator v. foot on break

Question

- From 300 fpm down to 0 fpm from 150 ft agl
- 40 seconds (about 4 seconds of burner)

- Does it matter when you put the burn in?
- How do you avoid over burning?
- Is the ET Exceeded?
- How would you stop the balloon more quickly?

What have you learnt?

- You may be falling but accelerating upwards.
- Once you reach the equilibrium temperature your rate of deceleration will increase.
- If you continue putting in the same burns all the way down you will over-burn.
- Half as much is a good rule.
- Now look at landing.

Landing

- Tony Brown – Concorde
- Always aim for the field before
- Line to the ground
- Adjust all the way down – under control
- Stop descent slightly above ground
- When ready, rip out in air and lock.
- Get ready for landing.

Adrenalin

- You are in a 1,000 ft / minute descent, there is only 400 ft before you hit the ground. If you put the burner on and leave it on will you avoid hitting the ground?

Control

- Never do anything else (except fly the balloon) for more than 10 seconds.
- If you are 500 ft above the ground a controlled descent rate is 500 ft/minute.
- 400 ft: 400 fpm
- 300 ft: 300 fpm
- Etc.

To Control a Balloon (Safely)

- Need to know what is happening at any point in time and understand why.
- Need to know what the balloon is capable of and its limitations.
- Understand the basic concept of the equilibrium temperature and the wide range (60 – 120) and how these relate to what the balloon does.

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