Question on types of Black Powder for ejection charge

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

scschulte

Well-Known Member
Joined
Jul 6, 2020
Messages
80
Reaction score
51
Location
Liège, Belgium
I am wondering if the Black Powder used in Cesaroni reloads to eject the parachute is 4F or if it is finer than 4F. I was using 3F BP for dual deployment but during a ground test last week it did not generate the oompf that I needed, so I re-ran the test using BP from Cesaroni motor ejection. (I save this when I launch my Endeavour-- a piston recovery rocket that cannot have the motor ejection charge going-off so rather than throw it away, I save it). That worked great-- but then I got some 4F black powder and when comparing the 3 BP's, I noticed quite a difference. As you can see in the attached photos (3F, 4F and "CTI" is the Cesaroni BP), the 3F is definitely a larger grain than the 4F. But the Cesaroni BP looks almost like "dust" -- I mean it is REALLY fine-- so I'm wondering if they use a different BP (i.e. not regular 4F) in their ejection charges for reloads?

Any comments appreciated.

Steve
Friday 15 April 2022
 

Attachments

  • IMG_6079D.jpg
    IMG_6079D.jpg
    138.1 KB · Views: 20
  • IMG_6078D.jpg
    IMG_6078D.jpg
    150 KB · Views: 21
  • IMG_6077D.jpg
    IMG_6077D.jpg
    164.8 KB · Views: 21
Here are the sizes of BP used for sporting purposes (sizes in mm):

1FG 1.68-1.19
2FG 1.19-.59
3FG .84-.29
4FG .42-.15
5FG .149

You can see there is quite a range for 4F. I fly a lot of CTI motors and have noticed they have a very consistent grain size, so maybe they are using 5F? Or just 4F that has been screened towards the smaller end of the scale. I do know that different brands of BP can perform quite differently, and maybe screening is part of that. I’ll have to check it out the next time I dump out a CTI charge.


Tony
 
Thanks Tony & Titan II--- I just found the reference to FFFFG (4F) on the FAQ page of Cesaroni's website. I am thinking this is 4F screened towards the smaller end of the scale. I'll be doing some more ground testing using my new 4F BP prior to launching my just completed modified MadCow "Broken Arrow" fiberglass 4" dia, 9'4" tall rocket in June this year. Redundant dual deploy - but should I go drogueless? 35 foot long x 6" wide Streamer? 36" Rocketman 1.0 CD drogue, 20" drogue or either drogue with the streamer attached to the drogue??? Hard to ground test that!

Steve
Friday 15 April 2022IMG_5931.jpg
 
The CTI stuff looks like Swiss Null B. Null B is listed to have a wide range of granulation (0.19mm-0.23mm), but in practice, people in Flintolock circles know Null B is much finer than 4Fg. Allegedly, Swiss basically sweeps up the fine "dust" left over from producing their other black powder grain sizes and then packages that up as Null B.
 
Very interesting. I see that the CTI BP does seem to form pea-size/smaller 'lumps' - likely moisture absorption with the small particle size. Again, I'll be ground testing to make certain my 4F is able to deploy my 5 foot Rocketman 2.2 CD chute. (Yes, the Belgian or German Flag - depending which way you go!)IMG_5387.jpg
 
Very interesting. I see that the CTI BP does seem to form pea-size/smaller 'lumps' - likely moisture absorption with the small particle size. Again, I'll be ground testing to make certain my 4F is able to deploy my 5 foot Rocketman 2.2 CD chute. (Yes, the Belgian or German Flag - depending which way you go!)View attachment 514319

Very nice!

Where do you live in Belgium? I lived in Lens from 2010-2014. Loved my time in Belgium!

I have a Madcow Broken Arrow and I use 1.6g of FFFFg for the main and drogue deployment charges, with a 2.0g backup in each. It looks like you have an extended payload bay, so I would think about starting your ground testing with about 1.8g of FFFFg for the main and work your way up from there. Make sure to pack the BP very tightly, it will greatly increase the effectiveness and decrease the amount you need.

For a drogue on a 98mm rocket of that length (assume it is about 8000g dry weight?), I usually use an 18" drogue. 20" would be fine, but if you start getting bigger than that, you are going to end up with a lot of drift.
 
Great comments, mtnmanak! Lens is nw of Mons and we are about 140 km east of where you lived-- little village of HERMEE near LIEGE and not that far from the lovely city of MAASTRICHT, NL. (But I launch 300 km north of my home with Tripoli Netherlands - north of Zwolle, NL! -- very well-organized and fine Prefecture - great friends!!) (I certified at BONG on 2 July 1991 -- in those days there were no levels! Now I'm level-2 -- level-3 "someday"!)

Appreciate the comment on packing the BP tightly. My ejection charge canisters can each hold up to 4 grams of BP - but they are wide and not tall -- I'm calculating 2.1 grams of 4F BP -- since I don't load BP until I am at the launch site I can pack it tight, use wadding then masking tape. But I'm going to ground test this again several times before the launch. If the video (2 sec long) plays, you'll see I got a good ejection with 2.1 gm of CTI BP - but the chute was not positioned correctly-- more testing soon! (Not the actual nosecone/payload bay for this test - wasn't finished yet!)
View attachment 2022-04-03 iPhone 5 Ejection Test Broken Arrow (2 sec) 30fps.mov

IMG_5949.jpg

Yes I did add-on about 20" of payload bay (makes it easy to attach the Mobius Maxi camera and also I will put my tracker inside with the antenna running into the nosecose). Your comments on drift with a larger drogue are exactly what I'm hearing from a number of people. I am considering just using a 35 foot long x 6" wide Rocketman streamer with no drogue parachute. I have a 30' long Kevlar® harness and don't believe the rocket will be going too fast when the main deploys at about 500 feet (backup altimeter set for 300'). But maybe for the first launch just a basic 20" drogue parachute…. Rocket at 8.1 kg (just under 18 lbs) with a Pro54 3 grain: 1266 J760-19A -- I should have an 9:1 thrust-to-weight ratio or a bit more with this motor-- and I want that for a first launch.

Thanks for your comments-- really appreciated!

Steve
Friday 15 April 2022
 
Just a note on BP history.
BP is typically used in Muzzle loading rifles. 4F (FFFF) is used as a primer in the pan for Flint lock rifles. It needs to be very fine (small grains) for easy ignition from the flint sparks and burn fast through the touch hole into the barrel chamber to ignite the main charge.
Courser, 2F or 1F, BP is typical for the main change that propels the projectile.

We want a very fast burn rate so use 4F BP in ejection charges.
 
Great comments, mtnmanak! Lens is nw of Mons and we are about 140 km east of where you lived-- little village of HERMEE near LIEGE and not that far from the lovely city of MAASTRICHT, NL. (But I launch 300 km north of my home with Tripoli Netherlands - north of Zwolle, NL! -- very well-organized and fine Prefecture - great friends!!) (I certified at BONG on 2 July 1991 -- in those days there were no levels! Now I'm level-2 -- level-3 "someday"!)

Appreciate the comment on packing the BP tightly. My ejection charge canisters can each hold up to 4 grams of BP - but they are wide and not tall -- I'm calculating 2.1 grams of 4F BP -- since I don't load BP until I am at the launch site I can pack it tight, use wadding then masking tape. But I'm going to ground test this again several times before the launch. If the video (2 sec long) plays, you'll see I got a good ejection with 2.1 gm of CTI BP - but the chute was not positioned correctly-- more testing soon! (Not the actual nosecone/payload bay for this test - wasn't finished yet!)
View attachment 514327

View attachment 514326

Yes I did add-on about 20" of payload bay (makes it easy to attach the Mobius Maxi camera and also I will put my tracker inside with the antenna running into the nosecose). Your comments on drift with a larger drogue are exactly what I'm hearing from a number of people. I am considering just using a 35 foot long x 6" wide Rocketman streamer with no drogue parachute. I have a 30' long Kevlar® harness and don't believe the rocket will be going too fast when the main deploys at about 500 feet (backup altimeter set for 300'). But maybe for the first launch just a basic 20" drogue parachute…. Rocket at 8.1 kg (just under 18 lbs) with a Pro54 3 grain: 1266 J760-19A -- I should have an 9:1 thrust-to-weight ratio or a bit more with this motor-- and I want that for a first launch.

Thanks for your comments-- really appreciated!

Steve
Friday 15 April 2022

Steve - while descent rate of the drogue is important to reduce drift, it is not as important for the opening of your main, in the sense that you can fly drogue-less and still have a safe main deployment (the drag of the separated rocket parts will keep the descent rate to a relatively slow terminal velocity). More importantly, though, is the relative position of the booster and payload bay when the main opens. Picking a drogue is a balancing act to find a good descent rate, yet ensure your entire assembly maintains a good "inverted V" while under drogue. This ensures the payload bay is not under the booster when the main is deployed. I have used streamers for drogues in smaller rockets, but when I get up to this size of rocket, I am concerned that a streamer will not have enough drag force to keep the assembly in an inverted V formation.

It can be surprising how small of a parachute you can use as a drogue. I have a rocket that weighs about 45-50 Kg on the pad and it works just fine with a 36" drogue.

Unfortunately, outside of making a good initial guess, the only real way to find out how well a drogue is going to work is to fly it.
 
Excellent points and another Tripoli member wrote to me separately about the "Inverted V" -- I think for my first flight I will use my 20" drogue (or even my 16") and do a lot of observing as I will keep this first flight under 2,000 feet max. Love to see a photo or video of that 40+kg rocket!

Here's a fun video/YouTube that I did of my Frenzy & Endeavour launches from Sept 2021:

Next issue: Screw Switches. I went to screw switches for my AvBay after thinking that slide switches were too susceptible to being pushed to the OFF position. But now realize the screws can easily come out (I've build a "cage" around the screw) and perhaps not the best solution for arming AvBays………

Steve
Friday 15 April 2022
 
But now realize the screws can easily come out (I've build a "cage" around the screw) and perhaps not the best solution for arming AvBays………

There are several threads discussing this in detail. They work great.
 
Excellent points and another Tripoli member wrote to me separately about the "Inverted V" -- I think for my first flight I will use my 20" drogue (or even my 16") and do a lot of observing as I will keep this first flight under 2,000 feet max. Love to see a photo or video of that 40+kg rocket!

Here's a fun video/YouTube that I did of my Frenzy & Endeavour launches from Sept 2021:

Next issue: Screw Switches. I went to screw switches for my AvBay after thinking that slide switches were too susceptible to being pushed to the OFF position. But now realize the screws can easily come out (I've build a "cage" around the screw) and perhaps not the best solution for arming AvBays………

Steve
Friday 15 April 2022


Here is a video:



Here are some photos from a launch a couple weeks ago on an N2220:

1650053817162.png

1650053839525.png

Build Thread:
https://www.mountainmanrockets.com/index.php/builds/8-inch-agm-33-pike-build/
 
Last edited:
Just a note on BP history.
BP is typically used in Muzzle loading rifles. 4F (FFFF) is used as a primer in the pan for Flint lock rifles. It needs to be very fine (small grains) for easy ignition from the flint sparks and burn fast through the touch hole into the barrel chamber to ignite the main charge.
Courser, 2F or 1F, BP is typical for the main change that propels the projectile.

We want a very fast burn rate so use 4F BP in ejection charges.

Hmmmmm..... "historically speaking"......
I absolutely agree that BP was used in muzzle-loading (ML) smooth-bore shoulder arms of all sizes and later rifles. But BP was also used in ML canons, ML pistols, and ML shotguns. And while it was used in Flintlocks, it was used much earlier in wheel-locks and in the even earlier fusil which became a generic word for gun, but originally a fusil was a very early ML gun that was ignited by the use of a fuse thru a touch hole like early cannons.

The mechanism for igniting the BP inside the barrel improved greatly over the years, from the ifrst simple touch holes fired with a match or fuse, to the mechanical fuse holder in the wheel-lock, to the flint-lock, to the percussion cap which was generally speaking, the last major innovation of the muzzle-loading era before the the invention of the rear/breech loading gun with a cartridge which held a pre-loaded percussion cap, the BP charge and the bullet inside a (usually) brass tube.

Most ML guns that I know of used 4F in the pan for later matchlocks/wheel-locks, and flintlocks because it was easy to ignite. The size of the BP inside the barrel was dependent mostly upon the diameter of the barrel. Most cannons used 1F. Most large bore shot guns used 2F. Most large smooth bore muskets like 60 cal plus used 2F. Most rifles in the 30 to 60 cal range use 3F. Pistols are another matter. I've seen originals loaded with both 3F and 4F. It depends on the pistol.

Often the size of the BP grain was limited by the quality of the metallurgy of the barrel itself. The larger grains of BP allowed for a slower build-up of pressure which kept the barrel from bursting from over pressure. Many old ML guns from the 1700's and early 1800's had proof marks stamped into the barrels by whatever government was legally certifying the barrel for use and export. The barrels were often "proofed" by firing them with a double charge of both BP and whatever was being shot out of the gun.

As to BP used in ejection charges, I used 3F for years without any problems because being one of those ML rifle guys, its what I had on hand. But these days I use 4F because I have it and I'm pretty sure that's what is recommended by the rocket motor folks for ejection charges. And if it works for motor ejection then it ought to work just fine for electronic motor ejection as well.

I suppose that's enough muzzle-loading history for now. I suppose that one could argue that most of our rockets are simply replicas of antique propulsion systems. I load my parachutes in the muzzle end of the rocket. I told the guy at the gun shop where I first bought some DuPont 4F that I needed it for my muzzle-loader. He didn't ask any more and I didn't offer any more. I must admit that it was just a bit of subterfuge on my part as some of the gun shops in those days would not sell BP to the "rocketry" community. I did have an actual muzzle-loader so I was telling the truth......mostly....... oh dear...... maybe I should just delete this whole post............

Well, I am a sinner and I guess here's proof for all to see, and oh dear its even Good Friday. Too late now........Fortunately I'm a forgiven sinner by that guy with the nail holes. And that was long before I was ever called the "Rocket Rev." Even after all these years, still only by His mercy.

Brad the "thankfully forgiven" "Rocket Rev.," Wilson
 
Back
Top