How to Determine the Amount of Ejection Charge for a High-Power Model Rocket

Рет қаралды 10,623

2 жыл бұрын

When you start flying large diameter rockets, and you are setting up dual deployment charges, the common question is how much black-powder do you need to ensure a successful deployment? How do you go about calculating the size of the black powder charge?
In this video, we'll cover these questions, as well as things like the different types of grain size for black powder, and where you will purchase it. We'll also talk about ground testing your deployment charges, and what constitutes a successful ground test.
Shear pins: www.apogeerockets.com/Buildin...

Пікірлер: 44

@bluewaterboof82 2 жыл бұрын

Thank you for this! I’ve been reading forum posts and whatnot about this subject but it is always super helpful for me to have a visual and auditory explanation.

@jodigant 2 жыл бұрын

Wonderfully explained Tim. Thanks for the video

@islandtime100 2 жыл бұрын

Thank you Tim; I am working on a fairly complex build and this answered many of my concerns. Also I am subscribed and liked the video to help get your videos more traction.

@apogeerockets 2 жыл бұрын

Thanks!

@johnjones947 2 жыл бұрын

Thank you for going through this in detail. I'm new to the sport, so I'm not quite to dual deploy yet, but I enjoy reading up on it. I notice on the lower end of high power rockets, you don't need to be concerned about having vent holes or sheer pins, however every dual deploy rocket I've seen has people recommending vent holes to prevent separation by pressure change on ascent, and sheer pins on both the ebay and the nose to prevent premature deployment. Is there a particular altitude or engine size that determines whether or not you need to add vent holes and sheer pins?

@johannesdesloper8434 2 жыл бұрын

Yes very cool vid. Here in the Netherlands we cannot own gunpowder without a permit so most use flashcotton but I hate that stuff. I'm asking myself if I could use the blackpowder from firecrackers. Those are legal to own and the powder comes in nice little stable units.

@lbeyyt6581 2 жыл бұрын

Can you do a short vid on how to add extra bp to the ejection well of a dms motor? I know most people do the making tape method, but it would be great to see a visualization

@moosoneerocketry9826 9 ай бұрын

Can you use Three F or Fffg? That is all I could find. Is there a calculator for Fffg? If I have to, I will use a Ffffg calculator and I will ground test of course. I will have my parachute well protected with a Nomex blanket.

@shekharsharma7295 Жыл бұрын

I love you You are awesome 👏

@normellow 6 ай бұрын

When in doubt, double it out.

@pisolo86 2 жыл бұрын

If you don’t have a backyard, which is the best location where to do a test like this? Great video!

@apogeerockets 2 жыл бұрын

someone else's backyard. You'll need to ask permission wherever you go.

@jasonb938 2 жыл бұрын

MidwayUSA , PowderValley for 4F

@larrytorres-ff3dp 11 ай бұрын

Great video!!! Now, what about the lower stage? If you have dual deployment, how do you calculate the bottom half of the rocket?? Especially with the motor installed…

@apogeerockets 11 ай бұрын

You do exactly the same thing for the lower stage. Find the volume of the compartment that needs to be pressurized to blow out the parachute.

@xxshooterxxdm 2 жыл бұрын

Blow is apart or blow it up

@tonysworksMGB 2 жыл бұрын

When will you have any 4” or bigger fiberglass kits in stock?

@apogeerockets 2 жыл бұрын

see our video at: kzfaq.info/get/bejne/gM-Kl5mh2LnHXZc.html

@stephenmartin4273 2 жыл бұрын

Thanks for the infos! I would like to know Tim if 3fg instead of 4Fg black powder would do?

@xxshooterxxdm 2 жыл бұрын

Yes but you need to test and if in doubt give it a dash more

@apogeerockets 2 жыл бұрын

I personally would use a ceramic mortar and pestal to grind the 3F down to 4f size. Be careful. Do it outdoors and away from others.

@stephenmartin4273 2 жыл бұрын

@@apogeerockets Thanks Tim!! Feeling a bit uncomfortable about grinding black powder LOL.. But will try instead finding 4Fg BP.

@AlChemicalLife 2 жыл бұрын

@@stephenmartin4273 grinding it with some wooden utensils like a wood dowel that has been rounded at one end and a wooden bowl or something non sparking is safe and is no cause for concern. Blackpowder is not friction sensitive or shock sensitive. I mill 2.5lbs of black powder every 2hrs with 35lbs of lead in a ball mill, if that gives you some idea of how rough you can be with it. Don't use ferrous metals or sparking objects or glass objects. Wood , aluminum , lead and brass are safe to use for grinding. Ceramic has a small chance of sparking, not to any significant degree but I would avoid it if you can.

@metalsurgeon9196 Жыл бұрын

My grandfather used to compete in black powder shooting, he would buy "raw" ,what he called it, and would process it in a glass mortar and pestle. He said the glass won't carry any static charge, and will make a finer grind.

@atomicall Жыл бұрын

What do I do if my parachute tube is not pressurized? Not sure how to calculate the force then...

@apogeerockets Жыл бұрын

I'd watch the video again. You have to pressurize the tube to blow out the parachute. If it is open, then you won't be able to get the chute out.

@atomicall Жыл бұрын

@@apogeerockets Okay because currently I was going to have my nosecone separate at apogee then deploy my drogue parachute. Then after falling for a while I would cut the drogue then launch the main. That means both of these tubes should have some sort of cap with shear pins installed on them in order for them to be pressurized correct?

@travelrideandfly8355 2 жыл бұрын

Hi. The spreadsheet is not there. Did you obsolete it ?

@apogeerockets 2 жыл бұрын

I'm sorry. It wasn't our spreadsheet, nor our website. So I don't have any control over it. Just do an internet search, and you'll find something.

@pilot76103 Жыл бұрын

Found it! www.aeroconsystems.com/tips/Ejection_ChargeCalc.xls

@jesuscoria5675 2 жыл бұрын

The link to your black powder calculator from your website no longer works.

@apogeerockets 2 жыл бұрын

That is why we don't like to put external links on our website. They often break because someone else controls them.

@roberth5435 3 ай бұрын

Why use black powder? It's dirty and corrosive. Smokeless powder compounded for muzzle-loaders substitutes exactly by weight, volume, and burn rate.

@rudraagrawal1988 2 жыл бұрын

Just a suggestion : please upload more videos a about rocketry building techniques and not rocksim 🙂

@apogeerockets 2 жыл бұрын

There will be plenty of building techniques videos. But we will support our RockSim users too. We're not leaving any customers behind.

@rudraagrawal1988 2 жыл бұрын

@@apogeerockets ohh, great!

@brocktechnology 3 ай бұрын

Area of a circle is pie r squared, yes your formula gives the same answer but I'm guessing your goal is NOT to scare away people that think there bad at math.