Adding addition powder for ejection to Enerjet and Economax motors?

[Back_at_it]

I recently picked up someone's collection of previously built rockets. Many were built for display and have never been flown. Of course I fly all of my rocket but I don't have a ton of room unless I'm flying up at Bong so I tend to use smaller motors. A few of the rockets are LOC kits like the LOC VI. It's 100% stock but built to pop the nosecone for recovery. I have flown it twice on F67-4's. The first time I had a successful deployment but the second launch the nose cone only popped and there wasn't enough force to push the laundry out.

I understand that a rocket this size has a lot of area to pressurize and I'm wondering if it's possible to add additional powder to something like the E30, F44, F67 motors to increase the ejection pressure. I have just flown my level one on an H550 which did allow for additional powder. Can this be done?

 

[DigBaddy]

Yup, pull out the cap, add a bit more BP, put cap back.

 

[Antares JS]

I recently picked up someone's collection of previously built rockets. Many were built for display and have never never been flown. Of course I fly all of my rocket but I don't have a ton of room unless I'm flying up at Bong. A few of the rockets are LOC kits like the LOC VI. It's 100% stock but built to pop the nosecone for recovery. I have flown it twice on F67-4's. The first time I had a successful deployment but the second launch the nose cone only popped and there wasn't enough force to push the laundry out.

I understand that a rocket this size has a lot of area to pressurize and I'm wondering if it's possible to add additional powder to something like the E30, F44, F67 motors to increase the ejection pressure. I have just flown my level one on an H550 which did allow for additional powder. Can this be done?

Your chute is not airtight and adding more pressure is not likely to help it come out. I would work on the folding method for your parachute or investigate to find some other reason it might be hanging up inside the rocket before thinking about adding more ejection powder.

 

[Handeman]

I've seen this same thing many times on similar rockets like the G-Force. MPR motors don't usually have enough powder to reliably push the nose cone off with enough energy that the inertia of the nose cone will pull the chute out of the BT. I saw one pop the nose cone only 2-3ft. from the BT and fall flat. When the rocket was picked up by the fins, the chute and remaining shock cord fell out of the BT. Obviously it wasn't hung up, just not enough ejection charge.

I would recommend adding powder to any MPR motor used in 4" diameter rockets, especially if they don't have a long MMT and forward CR to reduce the size of the payload area that needs to be pressurized.

 

[Back_at_it]

Your chute is not airtight and adding more pressure is not likely to help it come out. I would work on the folding method for your parachute or investigate to find some other reason it might be hanging up inside the rocket before thinking about adding more ejection powder.

The second flight was low enough that you could see that the force of the ejection wasn't strong enough to pop with enough force to extend the shock cord. It also "sounded" significantly softer than other ejections. The rocket that flew with an F44 a few minutes earlier had a noticeable bang when the ejection fired.

This could have just been a weak charge but it sounds like adding powder is at least an option.

 

[Back_at_it]

I saw one pop the nose cone only 2-3ft. from the BT and fall flat. When the rocket was picked up by the fins, the chute and remaining shock cord fell out of the BT. Obviously it wasn't hung up, just not enough ejection charge.

I would recommend adding powder to any MPR motor used in 4" diameter rockets, especially if they don't have a long MMT and forward CR to reduce the size of the payload area that needs to be pressurized.

This is exactly what happened. Nose cone only popped out a couple of feet and didn't extend the cord which was laying loosely on top of the chute. Typically when I build BT80 or larger I do so with a stuffer tube and only leave enough open area for the laundry. Unfortunately these rockets were built when I got them and they are really nicely finished so I didn't want to start cutting them up.

I'll be adding powder to the ejection for these rockets going forward. Thanks for the info.

 

[ThirstyBarbarian]

If the LOC IV was built with the nosecone option, not the center-break option, then the volume to pressurize is more than doubled. And the mass of just the nosecone is less than the constructed payload section, so there’s less momentum to pull the chute from the compartment. Plus the compartment is just much longer, leaving more room for things to get hung up. That’s why the LOC IV and similar rockets like the G-Force are better if built center-break style. But with an inherited rocket, you get what you get.

You probably do need more powder, to give the nosecone more momentum to yank the chute out. You can just pull the red cap out of the charge well and dump the supplemental powder in on top of what’s there, then push the cap back in. If the powder takes up too much room to get the cap back in, stuff a bit of dog barf in on top to keep the powder packed, then seal it up with masking tape. Or if you need a really big charge that’s bigger than the charge well, you can wrap masking tape around the end of the charge well to build up a cup, pour the powder in the cup/well, then pinch it closed, and seal the whole thing up with tape. However you choose to do it, try to make sure the powder is compressed or packed a little bit, not loose with a lot of space.

A couple other things to check or try — review your recovery loading technique like @Antares JS mentioned to be sure nothing is getting hung up and everything is set to be pulled out in the proper order. You don’t need a very long leader from the nosecone to the chute bundle, maybe 3 or 4 feet. The only thing sitting on top of the chute bundle should be that leader, and the rest of the shock cord needs to be loaded into the tube first, with the chute bundle on top of it. The nose cone pops and pulls the leader, leader pulls the chute bundle out, chute pulls the rest of the shock cord out. Last in, first out, nothing out of order.

You could add some weight to the nosecone to help it pull the laundry out, but if you add very much, you might have trouble using an F67 due to weight.

You might be able to add a chute shelf to keep the recovery gear forward and shorten the distance it needs to travel to get out of the tube. This wouldn’t make the volume any smaller, so you might still need more BP, but it would help to prevent the chute from hanging up inside. There are probably lots of ways to do it. One way would be if you were given the bulk plate for the unbuilt payload section, you could drill some holes in that to make a baffle, add the eyebolt for the recovery system anchor, and glue it into the tube at some point forward of the existing forward centering ring. You’d have to look inside the tube at where the coupler is to see how much room is available and be sure to leave enough room in the chute bay for everything to fit with the nosecone installed.

Good luck!

 

[waltr]

I also add BP to some motors for large tube rockets. The LOC 4" Goblin works best with 1gram BP and most motors have about 0.7gm. This also includes RMS reloads.

But I recommend do not just add BP. After pulling the cap off dump out the BP in the motor and check how much is there. Then add to the amount you wish.

It would not be a bad idea to check the amount of BP in every SU motor used. This should avoid the cases of under or over charge.

 

[Back_at_it]

If the LOC IV was built with the nosecone option, not the center-break option, then the volume to pressurize is more than doubled. And the mass of just the nosecone is less than the constructed payload section, so there’s less momentum to pull the chute from the compartment. Plus the compartment is just much longer, leaving more room for things to get hung up. That’s why the LOC IV and similar rockets like the G-Force are better if built center-break style. But with an inherited rocket, you get what you get.

You probably do need more powder, to give the nosecone more momentum to yank the chute out. You can just pull the red cap out of the charge well and dump the supplemental powder in on top of what’s there, then push the cap back in. If the powder takes up too much room to get the cap back in, stuff a bit of dog barf in on top to keep the powder packed, then seal it up with masking tape. Or if you need a really big charge that’s bigger than the charge well, you can wrap masking tape around the end of the charge well to build up a cup, pour the powder in the cup/well, then pinch it closed, and seal the whole thing up with tape. However you choose to do it, try to make sure the powder is compressed or packed a little bit, not loose with a lot of space.

A couple other things to check or try — review your recovery loading technique like @Antares JS mentioned to be sure nothing is getting hung up and everything is set to be pulled out in the proper order. You don’t need a very long leader from the nosecone to the chute bundle, maybe 3 or 4 feet. The only thing sitting on top of the chute bundle should be that leader, and the rest of the shock cord needs to be loaded into the tube first, with the chute bundle on top of it. The nose cone pops and pulls the leader, leader pulls the chute bundle out, chute pulls the rest of the shock cord out. Last in, first out, nothing out of order.

You could add some weight to the nosecone to help it pull the laundry out, but if you add very much, you might have trouble using an F67 due to weight.

You might be able to add a chute shelf to keep the recovery gear forward and shorten the distance it needs to travel to get out of the tube. This wouldn’t make the volume any smaller, so you might still need more BP, but it would help to prevent the chute from hanging up inside. There are probably lots of ways to do it. One way would be if you were given the bulk plate for the unbuilt payload section, you could drill some holes in that to make a baffle, add the eyebolt for the recovery system anchor, and glue it into the tube at some point forward of the existing forward centering ring. You’d have to look inside the tube at where the coupler is to see how much room is available and be sure to leave enough room in the chute bay for everything to fit with the nosecone installed.

Good luck!

All good points. I do have some 4" bulk heads that I could drill and use as shelfs. I feel like I could get a shelf down below the existing coupler. With the recovery harness attached to an eye bolt I would then use that to pull the shelf up tight against the bottom of the coupler.

 

[Handeman]

Another option if you don't want to use a shelf or add powder to the ejection charges is to use a piston. You can get good deployment with less powder when using a piston.

 

[ThirstyBarbarian]

All good points. I do have some 4" bulk heads that I could drill and use as shelfs. I feel like I could get a shelf down below the existing coupler. With the recovery harness attached to an eye bolt I would then use that to pull the shelf up tight against the bottom of the coupler.

Yeah. If you could get the plate past the coupler, that would be great. And now that I think about it, you definitely should be able to. You could just cut a bit off of one side of the plate and slide it down sideways. There might be a bit of awkward fiddling around with one arm down the tube, but I imagine it’s doable.

 

[Back_at_it]

Another option if you don't want to use a shelf or add powder to the ejection charges is to use a piston. You can get good deployment with less powder when using a piston.

The LOC IV has a coupler between the upper and lower tubes that would get in the way of a piston but that is a thought for larger rockets that don't have couplers.

 

[Back_at_it]

Had a chance to work on this a bit more yesterday and decided to check the amount of powder in a couple of F67-4 motors. The first showed .50gm while the second was .70.

Since these motors will be used in the LOC IV and Phantom that were built with nose cone ejection, I have increased the total amount of powder to 1.3gm. This still allows me to insert the plug and compress the powder. Hoping to get out to fly a couple of rockets this week before it gets too cold.

I'll come back with a flight report later in the week.

 

[waltr]

Wow, 0.7 & 0.5 grams is a pretty big difference and could cause a non-deployment.

I'm going to start checking every motor's change instead of depending on the manufacture.