Model Rocket Motors

Estes motors have been the primary model rocket motor used worldwide for many years since their introduction in the late 1960's. Literally millions have been fired by hobbyists and schools and they have achieved an exemplary safety record.

Rocket Store usually stock all the Estes motors at great prices which are legal for the UK market and these can be found in our Online Store. We are normally the cheapest in the UK for Estes motors. Just click on the Shopping image and you will be taken straight to these estes engines in our Online Store.

Introduction to Estes Motors

Estes motors are available in three diameter sizes, 13mm, 18mm and 24mm and in 4 different power bands and provide power from less than A up to D class power. If you are not familar with rocket motor impulse classes, then have a quick read of our factsheet.

Estes are the only black powder motors currently available in the UK and motors are available in A-D sizes. Estes do offer an E motor, however the E engine is not covered under the same pyrotechnic exemption in the UK as A to D are, and are therefore not legal in the UK unfortunately. This may change in the future.

These motors traditionally known as Black Powder motors are typically sold in packs of 3 or 4 and cost approximately £8 - £18 per pack depending upon size. The motors are ignited using small igniters provided with the motors.

UK Legal Estes Motors

There are a few Estes motors that aren't currently legal in the UK so we have put together a list of those ones legal for the UK market. If it isn't listed below then as far as we are aware they arent legal for the UK.

Name	Impulse Class	Diam(mm)	Peak Impulse(N)	Avg Impulse(N)	Burn Time(s)	Tot Impulse(Ns)
1/2A3-2T	< A	13	8.3	4.17	0.3	1.25
1/2A3-4T	< A	13	8.3	4.17	0.3	1.25
1/2A6-2	< A	18	8.9	4.17	0.3	1.25
A3-4T	A	13	6.8	4.17	0.6	2.5
A8-3	A	18	10.7	5	0.5	2.5
A8-5	A	18	10.7	5	0.5	2.5
A10-3T	A	13	13	3.13	0.8	2.5
B4-2	B	18	13.2	4.54	1.1	5
B4-4	B	18	13.2	4.54	1.1	5
B6-2	B	18	12.1	6.25	0.8	5
B6-4	B	18	12.1	6.25	0.8	5
B6-6	B	18	12.1	6.25	0.8	5
C5-3	C	18	21.9	5.3	1.7	9.5
C6-0	C	18	15.3	6.25	1.6	10
C6-3	C	18	15.3	6.25	1.6	10
C6-5	C	18	15.3	6.25	1.6	10
C6-7	C	18	15.3	6.25	1.6	10
D11-P	D	24	27.6	11.1	1.8	20
D12-0	D	24	32.9	10.2	1.7	16.8
D12-3	D	24	32.9	10.2	1.7	16.8
D12-5	D	24	32.9	10.2	1.7	16.8
D12-7	D	24	32.9	10.2	1.7	16.8

Anatomy Of An Estes Motor

A black powder motor is one of the simplist and reliable solid rocket motors available in the UK. As with all rocket motors, it has a motor case, however due to the low power of the motors, a cardboard casing is adequate.

The motor contains a clay nozzle. This is possible once again due to the low power of the motor. Next is the propellant, this is a mixture of Potassium Nitrate, Sulphur, Charcoal and Dextrin. This is then followed by the delay grain. The delay grain is a simple mechanism to stop the ejection charge from being detonated once the propellant has finished burning. This generates the coasting phase. The clay cap is used to just hold the ejection charge in.

What Do the Numbers Mean ?

A common question asked by many beginners is, what do those numbers and letters mean? Lets explain the example as shown above, the A8-3 motor.

B: The B letter indicates the total power (in Newton-seconds) produced by the engine. Each succeeding letter has up to twice the total power as the previous letter. (Example: "B" engines have up to twice the power of "A" engines, which results in approximately twice the altitude the rocket will reach.)

6: The number after the letter, in this example the 6 denotes the average thrust of the rocket motor in Newtons.

4: The last number, in this example the 4 denotes the time delay in seconds after the thrust phase finishes that the ejection charge will be fired. A few of the motors have a T after the number. This just denotes it is a mini motor, a 13mm diameter motor.