Why lowest Power Engine for First Fligh

So I'm looking to buy and launch my first set of rockets with my young kids. We went to our local model rocket club monthly launch and were hooked. When we go to do our first launch it will be with this group. I have picked some Estes rockets that I think will fit my needs for easy of building and fun launching and recovery. However I'm confused by the engines. I know they represent different sizes with higher numbers and letters being more powerful.

Below is the engine recommendations for one of the rockets.
Recommended Engines: B4-2(First Flight), B4-4, B6-2, B6-4, C6-3, C6-5

I think I finally figured out that the (First Flight) is to the lowest powered engine for the rocket. Do I have that right? Also why the recommendation to use the lowest power one for the first flight?

Thanks,
Andrew

Correct, typically the lowest acceptable power/impulse engine is recommended for the first flight to both limit the height that the rocket will go and to also allow you to "test" the quality of your build. Nothing worse than putting in the C6-5/3 for the first flight and losing a wing or having the launch lug come off at launch. Once you are confident in the rocket and your recovery capabilities, then you can move up the stack.

Hi new guy Best reason I can think of is to get used to the flight characteristics. After the B4-2 then the B6-4 then the C6-5. If you go right for the C6-5 it's possible to lose it because your not used to following something that small that high.

The B4 and B6 have the same total power but the B6 burns it's fuel faster. You will find, especially when you progress to more power(and you will ) there can be a lot of option among all the different manufacturers in the same power range. This really get's going when you get to the "E's" and above.

Have fun and ask questions, take photos if you can

andrewec2f said:

So I'm looking to buy and launch my first set of rockets with my young kids. We went to our local model rocket club monthly launch and were hooked. When we go to do our first launch it will be with this group. I have picked some Estes rockets that I think will fit my needs for easy of building and fun launching and recovery. However I'm confused by the engines. I know they represent different sizes with higher numbers and letters being more powerful.

Below is the engine recommendations for one of the rockets.
Recommended Engines: B4-2(First Flight), B4-4, B6-2, B6-4, C6-3, C6-5

I think I finally figured out that the (First Flight) is to the lowest powered engine for the rocket. Do I have that right? Also why the recommendation to use the lowest power one for the first flight?

Thanks,
Andrew

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Nice motor basics sheet from Estes:

https://www2.estesrockets.com/pdf/Estes_Model_Rocket_Engines.pdf

Hello Newbie:
Just so we're sure you understand one of the most important numbers on our motors. the last number -2,3,4,5 or 7 is the delay time after the motor burns it's propellant in Seconds.
Can't tell you how many times I've had to tell a dad in front of the kids at check in he's installed a motor with too long a delay for the mass of the model and will have to change it before it can fly.

As several have said the reason to use the lowest recommended motor for each models first flight is to get to know what your Finished model will do in free flight. As you grow in the hobby I'd also suggest visiting the NAR's web site and look closely at all the motor Thrust curves to better understand what each motor has to offer. For instance that B4-2 listed above has a pretty good kick in the pants at ignition even tho it's overall thrust is shorter then that of a B6-2.

In addition to what everyone said, I thought it's so that a newcomer doesn't lose his/her rocket on its maiden flight, get upset at the mfg, and then give up the hobby!

Welcome and have fun!

grapetang said:

In addition to what everyone said, I thought it's so that a newcomer doesn't lose his/her rocket on its maiden flight, get upset at the mfg, and then give up the hobby!

Welcome and have fun!

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I'm with you on this one, grapetang. I think that's part of it, but I know at least two newbies who went for the top motor, and produced two lawn darts...never returning to the hobby again!

Also keeping the altitude low on the first flight helps you to learn to fly your field, when first starting out it is very easy to not realize how much field you really need. Glad you're starting with a club too that definitely will help keep you coming back

Also, smaller motor usually allows you to see the whole flight, so that you can note any stability and/or recovery issues. If you can't see it, you don't know if it's working as designed.

Welcome!

In very broad terms, the letter indicates how high it will fly. A "B" motor will go twice as high as an "A" motor (in the same rocket with the same weight), and a "C" motor will go twice as high as a "B" motor. More precisely, the letter indicates the total amount of "kick factor" (what scientists call "impulse") the motor has. The numbers before the dash indicate the average rate at which the "kick" is released. For example a B12 motor (if one existed) would release its "kick" twice as fast as a B6, but would burn out it half the time. As mentioned above, the numbers after the dash represent the time in seconds from the time the "kick" ends until the parachute ejection charge is fired.

If you want to learn more rocket basics, I would highly recommend getting the book, Handbook of Model Rocketry, by G. Harry Stine and Bill Stine. There is a lot of information in there about the principals of rocketry, that are a applicable to model rockets as well as high power rockets.

https://www.amazon.com/dp/0471472425/?tag=skimlinks_replacement-20 to order or check out your local library.

It will have just about everything you need to know to get you started.
Also, finding and joining a local club can help. Many rocket folks are helpful and can answer many of the questions that you might have.

Hope that helps.

Greg

For my son and I, I sought out the smallest rocket that I could put the biggest engine in. I settled on an Alpha 3 with a C6-7. It was about 2 seconds after lift-off that I realized the err of my ways. That thing went WAY out of sight, took forever to 'float' back down. Even though we had only the slightest breeze that day, the hang-time was long enough that the rocket drifted away from the field, across a road, into a tree. That was the first/last flight for that rocket.

Jesse said:

For my son and I, I sought out the smallest rocket that I could put the biggest engine in. I settled on an Alpha 3 with a C6-7. It was about 2 seconds after lift-off that I realized the err of my ways. That thing went WAY out of sight, took forever to 'float' back down. Even though we had only the slightest breeze that day, the hang-time was long enough that the rocket drifted away from the field, across a road, into a tree. That was the first/last flight for that rocket.

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After a few rain's or a lot of time in the tree, it may come down... Have you checked to see if it's still AWOL? Even if the body tube, motor mount, and parachute are damaged beyond repair, the nosecone is usually salvageable (barring a cow sitting/stepping on it (I got my revenge... someone eventually got to eat it), or a lawnmower).

Jesse said:

I settled on an Alpha 3 with a C6-7. It was about 2 seconds after lift-off that I realized the err of my ways. That thing went WAY out of sight, took forever to 'float' back down. Even though we had only the slightest breeze that day, the hang-time was long enough that the rocket drifted away from the field, across a road, into a tree. That was the first/last flight for that rocket.

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I remember doing that with a white Alpha (regular, not III) on a cloudy day. Even with a streamer, what was I thinking?!??? White-on-white with a C6-7 and it just disappeared in the clouds. I remember packing up dejected only to stumble across it along the schoolyard fence on my way home. Talk about luck!!!

If you buy an Alpha and a 3-pack of C6-7's, the usual result is you end up wondering what to do with the other 2 engines.

The first flight engine isn't always the least powerful one. For instance, my daughter's Estes Wizard had these recommendations: 1/2A6-2, A8-3 (First Flight), A8-5, B4-4, B6-4, B6-6, C6-5, C6-7. I bought a pack of A8-3s and consulted this chart:


The local park had a couple of softball fields and was about 250x200, so I thought we were ok. The Wizard really moves on an A8-3, and even with a streamer it drifted in the breeze. I can't imagine it on a C6-5.
Maybe a pack of 1/2A6-2s would have been better.

BobH48 said:

If you buy an Alpha and a 3-pack of C6-7's, the usual result is you end up wondering what to do with the other 2 engines.

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That sounds about right.

Thanks everyone for the great advice. I'm ordering my rockets and engines to day and very excited.

andrewec2f said:

Thanks everyone for the great advice. I'm ordering my rockets and engines to day and very excited.

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Andrew,
Rocketry is exciting! Let us know how it goes for you and the kids... and post some pictures - we love pictures here!!!!


very old pictures of my kid's launching their first rockets

Exactly! Mine are 3 and 5 and can already tell you about impulse, delay, reloads and fillets.

gna said:

The first flight engine isn't always the least powerful one. For instance, my daughter's Estes Wizard had these recommendations: 1/2A6-2, A8-3 (First Flight), A8-5, B4-4, B6-4, B6-6, C6-5, C6-7. I bought a pack of A8-3s and consulted this chart:

The local park had a couple of softball fields and was about 250x200, so I thought we were ok. The Wizard really moves on an A8-3, and even with a streamer it drifted in the breeze. I can't imagine it on a C6-5.
Maybe a pack of 1/2A6-2s would have been better.

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I am a little dubious of this chart: apparently they say it's OK to fly models with an expected peak altitude 4x the size of your field.

If you have anything more than a whisper of a breeze, I don't think that's going to work: if you launch a small model on an "A" to 400 feet, it is very likely to drift more than 200 feet with the wind direction.

If you are VERY experienced in reading wind currents and directions, you could get lucky and get some of your rockets back, but more likely a good percentage of them are going to go drifting cross country.

.5x - .7x the expected altitude would be more realistic.
Rex

JStarStar said:

I am a little dubious of this chart: apparently they say it's OK to fly models with an expected peak altitude 4x the size of your field.

If you have anything more than a whisper of a breeze, I don't think that's going to work: if you launch a small model on an "A" to 400 feet, it is very likely to drift more than 200 feet with the wind direction.

If you are VERY experienced in reading wind currents and directions, you could get lucky and get some of your rockets back, but more likely a good percentage of them are going to go drifting cross country.

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I agree. My side yard is 100ft X 150ft and I only launch Micro Maxx (1/8A) rockets at home. I would never attempt to fly even a 1/2A model in my yard if I was hoping to get it back.