Get Help With The Model Rocket Engines/motors.

Please choose one of the following:

• What the engine code means?
• Do I need to buy the engine or it is included with the rocket?
• The description says I can use several different engines, which one do I choose?
• Do I also need igniters or wadding?
• What is the difference between all these engines?
• Can I launch my Estes/Quest/Custom rocket with engines other than in recommended list?

What the engine code means? The code for rocket motors looks like B6-4 or F25-4W. The first letter is a range of the total impulse (or total power) produced by the engine. Each next letter has up to twice the total impulse. The number before letter "A" says that the impulse is a half or a quarter of an "A" motor.

First Letter	Total Impulse N	Total Impulse Lbf
A	1.26 - 2.50	0.29 - 0.56
B	2.51 - 5	0.57 - 1.12
C	5.01 - 10	1.13 - 2.24
D	10.01 - 20	2.25 - 4.48
E	20.01 - 40	4.49 - 8.96
F	40.01 - 80	8.97 - 17.92
G	80.01 - 160	17.93 - 143.83

The first number following the first letter tells us the average thrust in Newtons. So in case of our B6 motor we can now tell that the motor will burn for less than a second, since total impulse is 5 and average thrust is 6. We can also tell that A8 engine has more average thrust than B6, however the rocket will go higher on B motor, because it will burn longer. The number after the dash represents the delay from the motor burnout to the firing of the ejection charge in seconds. The delay is needed, because rocket will continue coasting upwards for some time. Then the ejection charge will push the parachute out and let the rocket land nicely to the ground. Aerotech motors have another letter right of the last number, this letter tells what kind of propellant is used. Please see code explanation here.

Do I need to buy the engine or it is included with the rocket? In most cases engines are not included with the set or the rocket and you need to buy them separately. The only exception are combos, which include everything you need for launch.

The description says I can use several different engines, which one do I choose? In our listings we arrange the engines from less powerful to the ones having most thrust. Pick the one that is first on the list of recommended engines for the first flight. If the first flight is successful, you can try more powerful engines. We recommend trying the engines with different first digit. For example: take this list of recommended engines: A8-3,B4-4,B6-4,C6-5. Pick A8-3 for the first flight. You can then launch C6-5 to see how far your rocket is going to fly. However it is worth trying B4-4 to enjoy slower take-offs.

Do I also need igniters or wadding? You always need igniters. The good news - they are always included with the engines. You might need extra if you break them, but this does not happen often. Estes bulk packs include more igniters than you need and you end up having few extra igniters. We recommend buying extra igniters for Aerotech motors. Yes, you need to get wadding or a heat shield*. Wadding is a flame-resistant paper that serves as a barrier between hot ejection charge and the parachute or streamer. Heat Shield is a piece of flame resistant cloth that you can reuse. You need wadding or heat shield unless you are launching Aerotech mid-power rockets. They have the built-in gas cooling system. Never substitute the recovery wadding with any other non-certified material. * All Engine Bulk Packs include wadding.

What is the difference between all these motors? You will find 2 different brands of motors on this site. Estes and Aerotech

Estes engines sold on this web site are powered by compressed black powder.

Aerotech produces totally different breed of engines fueled by composite propellant. This propellant is on average 3 times more powerful than black powder. The ignition and launch of composite motor powered rocket looks more like a real rocket accompanied by a loud roar. To launch composite motor powered rockets you need more powerful 12v launch controller.

Aerotech also produces reloadable motors to keep the cost down. To use reloadable motor, you need to buy motor casing and reloads.

Can I launch my rocket with engines other than in recommended list? Only when you have experience launching mid-power rockets, have knowledge about engine thrust and aerodynamics, have a launch site that is big enough for the bigger engines - you can consider using the engines other than recommended. Neither we (Denau Hobby Supplies Ltd.), or manufacturer of rockets or engines - endorsing the use engines other than recommended in any rocket we sell.