Motors, Igniters & Wadding
There is a lot to talk about when it comes to motors, even though I am a long way from understanding everything about motors I am going to explain what I have learnt about the most common brand and type of motors available here in the UK
The key things to know about a standard rocket motor from ESTES
- Cylindrical shape.
- Made from cardboard.
- They burn a black powder fuel.
- Most have a delay timer after the fuel is burnt.
- After the delay, there is a small out of the top of the motor.
ESTES have a fantastic range that starts from their own Tiny class of motor and goes all the way up to the F class of motor.
If you are buying your rockets online then most will say on the product page which rocket motors are compatible with your rocket. If not then go to the manufacturer’s websites and it will be listed there.
Bigger isn’t always better when flying your rocket for the first time. Some great advice is to start with the smallest that your rocket is compatible with when flying your rocket for the first time. You can think of your first flight as a shakedown test to make sure everything is good. If your flight characteristics are good then you can progressively go bigger on your motor choice to see just how far you can push it.
By using a smaller motor during the shakedown the theory is you will limit the potential damage that can be caused. All being well you can fix all the issues and try the shakedown test again. This will save you from sitting on the sidelines all day because your rocket got obliterated on the first flight.
The Classification System
There is a classification system that I have already mentioned a little so far but now I am going to break it down as simply as I possibly can without getting too technical.
Examples 1/2A6–2 or C11–3
The first letter is the power level classification of the motor. The maximum power doubles from one letter to the next. So a “B” motor can have twice the power of an “A” motor; which means it will fly approximately twice as high.
if the letter has a 1/2 before it thinks of this as having half the amount of fuel so its flight length is halved.
The first number after the power letter is the average thrust level of the rocket. to put it simply the bigger the number the faster it will fly.
If you have and A6 and A8 launch at the same time they will both have the same amount of fuel in each tube but the A8 will burn that fuel quicker because it has a higher thrust value and needs more fuel to go faster. The A6 may not go as fast but the motor will burn for longer as the thrust is lower and therefore speed of the rocket is slower.
The number after the dash is the length of the delay before the ejection charge, which deploys your parachute or streamer. The delay allows time for the rocket to naturally decelerate and reach apogee so the streamer parachute doesn’t get damaged by ejecting at high speed
If the number is 0 then the motor has no ejection charge and this type of motor has a special use circumstance which we will talk about in a later post.
A “T” at the end in the case of ESTES motor designates that it is a tiny configuration motor and therefore has a 13mm diameter and a 45mm length which is surprisingly small for a motor but ESTES has a range so check it or if your a scratch builder then why not take on that challenge… Bigger isn’t always better.
When you buy ESTES motors you also get the right igniters to fit and the end of the motor and the plugs to secure it so that you can ensure that the cable from the launch controller doesn’t pull it out before launch
There is one thing I briefly want to talk about which is wadding. Wadding is a fire retardant cloth or paper that you stuff into the end of your rocket between the motor and the parachute or streamer. This means that when the explosive charge at the end of the motor fires the sparks and hot gasses push the wadding which in turn pushes the parachute out. The wadding acts as a fire break and ensures that the parachute does get damaged and can be used repeatedly to recover your rocket.
That’s a quick overview of ESTES motors and a great start to your rocket hobby but at some point soon I will be talking about multi-use rocket motors as and when I get time to have a go myself.
Happy landings or at least have some fun trying