Estes, the most popular brand in model rocketry, offers a wide range of engines, each designed for specific rocket sizes, weights, and performance levels.
This guide breaks down the Estes engine coding system, thrust classes, and recommended uses, and provides an expanded engine chart for quick reference.
Estes Rocket Engine Chart
| Engine | Total Impulse Class | Average Thrust (N) | Delay Options | Typical Altitude | Best For |
|---|---|---|---|---|---|
| ½A3‑2T | ½A | 3 N | 2 sec | 50–100 ft | Small starter rockets, indoor fields |
| ½A6‑2 | ½A | 6 N | 2 sec | 80–120 ft | Tiny lightweight rockets |
| A3‑4T | A | 3 N | 4 sec | 200–300 ft | Mini models, small lightweight rockets |
| A8‑3 | A | 8 N | 3 sec | 300–500 ft | Beginner rockets, low-altitude flying |
| B4‑4 | B | 4 N | 4 sec | 300–600 ft | General flying, school projects |
| B6‑2 | B | 6 N | 2 sec | 500–800 ft | Slightly heavier rockets |
| B6‑4 | B | 6 N | 4 sec | 500–800 ft | Slightly heavier rockets |
| B6‑6 | B | 6 N | 6 sec | 900 ft | Heavier B-class rockets |
| C5‑3 | C | 5 N | 3 sec | 700–900 ft | Low-weight medium rockets |
| C6‑3 | C | 6 N | 3 sec | 900–1,500 ft | Workhorse engine for many rockets |
| C6‑5 | C | 6 N | 5 sec | 900–1,500 ft | Workhorse engine for many rockets |
| C6‑7 | C | 6 N | 7 sec | 900–1,500 ft | Workhorse engine for many rockets |
| C11‑3 | C | 11 N | 3 sec | 500–700 ft | Medium rockets needing extra thrust |
| D12‑3 | D | 12 N | 3 sec | 1,000–1,600 ft | Larger, heavier rockets |
| D12‑5 | D | 12 N | 5 sec | 1,000–1,600 ft | Larger, heavier rockets |
| D12‑7 | D | 12 N | 7 sec | 1,000–1,600 ft | Larger, heavier rockets |
| D16‑6 | D | 16 N | 6 sec | 1,400–1,800 ft | Heavier mid-power rockets |
| E9‑4 | E | 9 N | 4 sec | 1,500–2,000 ft | Mid‑power rockets; long burn time |
| E9‑6 | E | 9 N | 6 sec | 1,500–2,000 ft | Mid‑power rockets; long burn time |
| E12‑4 | E | 12 N | 4 sec | 1,700–2,200 ft | Heavy models with high-altitude goals |
| E12‑6 | E | 12 N | 6 sec | 1,700–2,200 ft | Heavy models with high-altitude goals |
| E12‑8 | E | 12 N | 8 sec | 1,700–2,200 ft | Heavy models with high-altitude goals |
| E16‑6 | E | 16 N | 6 sec | 1,900–2,300 ft | High-altitude heavy rockets |
| F15‑6 | F | 15 N | 6 sec | 2,000–2,800 ft | Larger mid‑power flight, heavy payloads |
| F15‑8 | F | 15 N | 8 sec | 2,000–2,800 ft | Larger mid‑power flight, heavy payloads |
| F44‑4 | F | 44 N | 4 sec | 2,500–3,500 ft | High-thrust heavy rockets, advanced users |
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Understanding the Estes Engine Coding System
Each Estes rocket engine is labeled by a combination of letters and numbers (e.g., A8‑3, C6‑5).
Here’s what each part means:
1. Engine Class (Letter)
The first letter (A, B, C, D, etc.) indicates the total impulse—the total power delivered by the engine.
- ½A – lowest power
- A – small rockets, low altitude
- B – beginner rockets, moderate altitude
- C – larger rockets, high altitude
- D, E, F – mid‑power engines, heavier rockets, long flights
Each step up roughly doubles the total power.
2. Average Thrust (First Number)
The number after the letter describes average thrust in Newtons (N).
Example: A C6 engine has an average thrust of 6 N.
3. Delay Time (Second Number)
The final number is the delay in seconds before the ejection charge fires.
Example:
- C6‑3 → 3‑second delay
- C6‑5 → 5‑second delay
Choosing the correct delay ensures parachute deployment at the right moment.
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How to Choose the Right Estes Engine
Selecting the right engine depends on:
1. Rocket Weight
Heavier rockets require higher thrust (e.g., C6, D12).
Light rockets can use low‑impulse motors.
2. Launch Field Size
Small fields → ½A to B engines
Large open areas → C, D, E, F engines
3. Flight Objective
- High altitude → Higher impulse engines (C, D, E)
- Slow controlled lift‑off → 3–6 N thrust engines
- Long burn → E9, F15 series
4. Recovery System Timing
Delay selection affects when the parachute deploys.
For fast rockets, choose a longer delay (5–7 seconds).
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Tips for Safely Using Estes Rocket Engines
- Always use an official Estes launch pad and controller.
- Check that the igniter is firmly placed and secured with the plastic cap.
- Keep spectators at least 15 feet away for small rockets, 30 feet for larger ones.
- Never reuse single‑use motors.
- Inspect the rocket body tube, fins, and parachute before each launch.
Advantages of Using an Estes Engine Chart
The Estes engine chart is helpful because it:
- Allows easy comparison of motor power levels
- Helps pair the correct engine to the rocket’s weight
- Prevents over‑powering or under‑powering
- Improves flight height and stability
- Ensures ejection charges fire at the correct time
- Supports safer launches
Whether you’re a beginner launching your first A8‑3 engine or an enthusiast stepping up to an E12 or F15, the chart makes engine selection simple and accurate.
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FAQs
What do the numbers on Estes rocket engines mean?
Estes rocket engines use a code like C6‑5. The letter (C) indicates the total impulse or overall power of the engine. The first number (6) represents the engine’s average thrust in Newtons (N). The second number (5) is the delay time in seconds before the ejection charge deploys the parachute.
What is the most powerful Estes engine?
The most powerful commonly available Estes engines are F‑class motors, such as the F44‑4. These engines deliver very high thrust (44 N) and can lift larger rockets to altitudes of 2,500–3,500 feet. They are intended for advanced users and require large, open launch areas.
What size motor is in the Estes rocket?
The size of an Estes rocket motor depends on the rocket model and recommended engine class. For example:
- Small starter rockets → ½A3‑2T or A8‑3
- Beginner rockets → B6‑4
- Medium rockets → C6‑5
- Larger rockets → D12‑5 or E12‑6
- Check the rocket’s instructions for the exact recommended engine.
What is the Estes B4‑4 rocket engine?
The B4‑4 is a beginner-friendly rocket engine.
- Class: B (moderate power)
- Average thrust: 4 N
- Delay: 4 seconds
- It is ideal for general flying, school projects, or rockets that need moderate lift without excessive altitude.
What does B6‑4 mean?
The B6‑4 engine code breaks down as follows:
- B: Total impulse class (medium power)
- 6: Average thrust in Newtons
- 4: Delay in seconds before the ejection charge deploys the parachute
- It’s a versatile engine for slightly heavier beginner or mid-size rockets.
What is the Estes C6‑7 rocket engine?
The C6‑7 is a workhorse mid-power engine:
- C class: Moderate-high total impulse
- 6 N average thrust
- 7-second delay
- It is suited for medium rockets where a longer delay ensures parachute deployment near the peak of the flight.
What is the Estes C6‑5 rocket engine?
The C6‑5 engine is similar to the C6‑7, but with a slightly shorter delay:
- C class: Moderate-high power
- 6 N average thrust
- 5-second delay
- It is widely used for medium rockets, offering reliable altitude while deploying the recovery system at the correct time.
