Help! Smoke Generator(Powder) for RC electric planes

[cdfigueredo]

Yes, for sure.

The biggest problem I see is that as the pitch of the helical is shortened, the amount of material to print it increases and therefore the weight. In addition, the capacity of the tank decreases. But I think it can work to print several helicals with different pitches and try it out.

 

[cdfigueredo]

Note, the screw goes past screw housing so powder can fall out without bogging or binding. Inverted or not.

Excuse me for my English, but what does this really mean?

 

[Apis]

Excuse me for my English, but what does this really mean?

I mean that the screw should poke out a little past the tube/cylinder for the screw. Also it shouldn't run into a wall, it should end into empty space so the powder can fall away and not get packed and rammed into a hard surface. I'm worried that the screw with break if the powder backs up in the exit chamber and the screw presses against this packed material.

I might be over thinking the powder issue.

EDIT: on second thought. Ignore the screw length. Just make a prototype to test.

 

[cdfigueredo]

I mean that the screw should poke out a little past the tube/cylinder for the screw. Also it shouldn't run into a wall, it should end into empty space so the powder can fall away and not get packed and rammed into a hard surface. I'm worried that the screw with break if the powder backs up in the exit chamber and the screw presses against this packed material.

I might be over thinking the powder issue.

EDIT: on second thought. Ignore the screw length. Just make a prototype to test.

I understand! i think that using the last diagram that you published there will be no problem with the compactness of the powder. anyway i think that the first step is to design a simple prototype and make it more complex if it really doesn't work or can be improved.

 

[cdfigueredo]

Here is the a prototype of the concept.

i Think the first attempts should be without any fan. At least to try the smoke generation at speed.

This version has 14 "steps", so if we assume that the servo rotates at a rate of 1 turn of 360 degrees per second, then it would take the tank 14 seconds to empty, which provides very little smoke. To increase the smoke time there are two options:
1- Increase the number of "steps" (with all the disadvantages this brings).
2- Decrease the servo speed (which I am not sure if it will be proportional to the movement of the potentiometer on the transmitter).

 

[cdfigueredo]

Last night I got this design pretty close to a working prototype. The green piece is the tank cap, filling is done by turning the plane upside down and removing the purple hood and the green cap. Finally the green cap is inserted using the clamps on both sides and the purple piece is reinserted. This yellow piece can be used as helper to fill the tank

 

[cdfigueredo]

Notice how the servo wires pass through the pylon.

 

[cdfigueredo]

about 110g if printed in PLA.

 

[Apis]

I think we're onto the beginnings of functional design with this version. Its much more simple and should be easier to refine and troubleshoot compared to previous attempts.

 

[cdfigueredo]

I think we're onto the beginnings of functional design with this version. Its much more simple and should be easier to refine and troubleshoot compared to previous attempts.

I agree! thank to you for your inputs.

 

[cdfigueredo]

IT is here https://www.thingiverse.com/thing:6329351
The printable prototype is ready. I've already sent some parts to print but it's going to take me a while to pick them up, so I'd appreciate if someone wants to give it a try.

 

[cdfigueredo]

I already have my prototype printed and ready for flight test. The model needs some improvements but I will make them after flight testing this version. At least the powder pusher mechanism works and the radio configuration was very easy. I will try this afternoon to test on the test bench if the thrust generated by the propeller turns the powder into smoke.

This Friday I will try to test it, wait for video.

 

[Apis]

I already have my prototype printed and ready for flight test. The model needs some improvements but I will make them after flight testing this version. At least the powder pusher mechanism works and the radio configuration was very easy. I will try this afternoon to test on the test bench if the thrust generated by the propeller turns the powder into smoke.

This Friday I will try to test it, wait for video.
View attachment 241101

Now that I'm looking at it without the shroud, if this works, these would be nice on the wingtips to show off wingtip vortexes.

EDIT: which guide did you follow to make the servo's continuous/360 compatible?

 

[cdfigueredo]

Now that I'm looking at it without the shroud, if this works, these would be nice on the wingtips to show off wingtip vortexes.

EDIT: which guide did you follow to make the servo's continuous/360 compatible?

Ohhh, placing them on the wingtips whould work great, haven;t think about that before. great idea.
I watched a flite test video, here is the link

 

[cdfigueredo]

Now that I'm looking at it without the shroud, if this works, these would be nice on the wingtips to show off wingtip vortexes.

EDIT: which guide did you follow to make the servo's continuous/360 compatible?

I even think that putting them on the wingtips would be a great idea to avoid the dirt produced by the powder on the fuselage.

 

[cdfigueredo]

It works. Has plenty room for mods but it works.

Edited to give more details of the experiments, results and possible improvements.

Conditions

• I performed two tests, with and without the hood, each video corresponds to one of the tests.
• Both tests were done by filling the compartment to approximately 80% of its capacity.
• I used wheat flour which was what I had on hand, which is quite heavy compared to baby powder.
• In both tests the mtor was accelerated to 100% and the servo was spun at its highest speed.

Results and conclusions

• The auger outlet is very wide and a lot of powder falls to the ground before it is mixed with the air.
• Better results are obtained when the hood is used to redirect the air to the auger outlet.
• With the servo at full speed you get only a few seconds of smoke, about 14 seconds (this is because the servo turns about one turn every second, and the worm has 14 turns).
• Nevertheless the effect is achieved.

Improvements

• The system must be tested in flight, as the higher speed will cause the falling dust to disperse with the air, generating a greater volume of smoke.
• The hood should be lengthened so that it is longer than the auger, so that the excess dust will fall into the hood and mix with the air.
• The exit hole of the hood should be narrower to better concentrate the smoke trail.
• It would be good to increase the capacity of the tank or at least try reducing the output speed to get more duration of effect.
• I also think that testing with colored powder would be excellent to be able to observe the effect better.

I think that as a prototype it showed that the design is functional, now it only remains to improve it.

 

[Apis]

It works. Has plenty room for mods but it works.

Edited to give more details of the experiments, results and possible improvements.

Conditions

• I performed two tests, with and without the hood, each video corresponds to one of the tests.
• Both tests were done by filling the compartment to approximately 80% of its capacity.
• I used wheat flour which was what I had on hand, which is quite heavy compared to baby powder.
• In both tests the mtor was accelerated to 100% and the servo was spun at its highest speed.

Results and conclusions

• The auger outlet is very wide and a lot of powder falls to the ground before it is mixed with the air.
• Better results are obtained when the hood is used to redirect the air to the auger outlet.
• With the servo at full speed you get only a few seconds of smoke, about 14 seconds (this is because the servo turns about one turn every second, and the worm has 14 turns).
• Nevertheless the effect is achieved.

Improvements

• The system must be tested in flight, as the higher speed will cause the falling dust to disperse with the air, generating a greater volume of smoke.
• The hood should be lengthened so that it is longer than the auger, so that the excess dust will fall into the hood and mix with the air.
• The exit hole of the hood should be narrower to better concentrate the smoke trail.
• It would be good to increase the capacity of the tank or at least try reducing the output speed to get more duration of effect.
• I also think that testing with colored powder would be excellent to be able to observe the effect better.

I think that as a prototype it showed that the design is functional, now it only remains to improve it.

Congratulations! It works! Now it's time to iterate for optimation!

 

[cdfigueredo]

Congratulations! It works! Now it's time to iterate for optimation!

Exactly! Now to make the necessary modifications so that it really is something we can all use. For that we have to improve two elements, efficiency and usability. It must produce smoke for a reasonable time that really merits adding 100g (for now) more weight to the model and on the other hand it must be easy and comfortable to disassemble, refill the tank and finally clean the residual powder.

But if there is one thing I can say is that this project would have reached this result without the help of you and some other people outside this forum.

 

[cdfigueredo]

I am working on a second prototype using the principles of the Coanda effect. The new advantages are in theory a reduction of the diameter of the bell and therefore a reduction of the height of the system, because it tends to rub the ground when it is located in the belly of the model. And also a decrease in weight and easier assembly. I also moved the suggestion point more towards the center to achieve a better balance, as the current one tends to have too much pull on the mount.
Plus it looks very cool to me .

 

[Apis]

I am working on a second prototype using the principles of the Coanda effect. The new advantages are in theory a reduction of the diameter of the bell and therefore a reduction of the height of the system, because it tends to rub the ground when it is located in the belly of the model. And also a decrease in weight and easier assembly. I also moved the suggestion point more towards the center to achieve a better balance, as the current one tends to have too much pull on the mount.
Plus it looks very cool to me .
View attachment 241111 View attachment 241112 View attachment 241113 View attachment 241114

I am worried that for air collected from plane forwards movement and propeller wash that the restrictions to the openings in this model will be too harsh.

I do think the shroud assembly looks markedly improved as compared to the last version. How do you keep the top and bottom halves of the shroud connected?

EDIT: this new design makes me want to stick a small fan on front for active air flow