Pulse Jet Aircraft

[telnar1236]

*Video not available👍

Looks like the guy who posted it made it so you need to open it directly on Youtube - guy seems like he knows what he's talking about - one useful and telling statistic though that he points out is that you only get 0.18 psi of ram air pressure even at 100 mph (he rounds down to 0.17 but it's 0.1798 psi). You really need to be going quite fast for the air pressure into the inlet to actually help very much and as he points out, at low speeds, you might be getting 20% of thrust out the inlet which corresponds to a 40% loss compared to an inlet pointing backwards since that's 20% lost and then 20% cancelled out by the flow out the front

 

[Houndpup Rc]

Looks like the guy who posted it made it so you need to open it directly on Youtube - guy seems like he knows what he's talking about - one useful and telling statistic though that he points out is that you only get 0.18 psi of ram air pressure even at 100 mph (he rounds down to 0.17 but it's 0.1798 psi). You really need to be going quite fast for the air pressure into the inlet to actually help very much and as he points out, at low speeds, you might be getting 20% of thrust out the inlet which corresponds to a 40% loss compared to an inlet pointing backwards since that's 20% lost and then 20% cancelled out by the flow out the front

Ah, thanks!🤦‍♂️😂👍

 

[telnar1236]

Designing your own pulse jet is one of the cases where I would strongly advocate for learning some math and doing quite extensive research in the RC world - there aren't any moving parts so you don't need to worry about throwing a blade like with a turbine, but you are still working with red hot metal, flames that will be burning at thousands of degrees, and explosive fuels so this one those things you want to do right to avoid hurting yourself or anyone else. No plane, no matter how cool, is worth getting hurt for

 

[Bearcat]

Considering all of that and wanting the best chances of a working plane I think I'm just going to copy that design I showed a while ago. Somebody much smarter than me designed it and I think It will work much better than any custom design I could come up with. That being said I would like to try making my own in the future but for my first I stick with what works. I just designed mini slip roller that ill use to bend the cones tomorrow hopefully. If it gets done tomorrow I was wondering If anyone knows how the fuel systems work on these

 

[Mr Man]

Considering all of that and wanting the best chances of a working plane I think I'm just going to copy that design I showed a while ago. Somebody much smarter than me designed it and I think It will work much better than any custom design I could come up with. That being said I would like to try making my own in the future but for my first I stick with what works. I just designed mini slip roller that ill use to bend the cones tomorrow hopefully. If it gets done tomorrow I was wondering If anyone knows how the fuel systems work on these

I've heard it's 10x easier to run one off of propane than off gasoline if that helps

 

[Bearcat]

I've heard it's 10x easier to run one off of propane than off gasoline if that helps

Yeah I've also heard that my issue is trying to store propane on a plane without too much weight that's why I was thinking gas. I have seen people on YouTube start them on propane and then switch to gas once there warm tho so maybe I could try that.

 

[telnar1236]

One thing to keep in mind with any liquid fuel is that you need a way to get it into the engine, either a fuel pump or a system to pressurize the fuel tank or a venturi. You may also run into issues with inverted flight and low G flight like power dives since the fuel may move around a fair bit. In contrast, propane is much simpler, you simply open the valve and are ready to go since the tank self-pressurizes. Butane might be an option if you live somewhere warm and don't need a ton of power since it has a lower vapor pressure and therefore lighter tanks

 

[Bearcat]

I'll look into the butane but I would like to stick to gas AI told me about pressurizing the tank via the pulses from the engine so I'll probably end up doing that

 

[Bearcat]

Got the new one designed from that drawing. Also watched some YouTube on bending metal into cones. I am hoping to get all parts cut out today and maybe start ending but well see hw that goes. I only have access to a stick welder currently so I may have t wait on that too. Any advice on bending/welding sheet metal would be appreciated!

 

[Bricks]

Years ago replacing car panels we would use lead and acetylene torch not sure if the melting point is high enough at 621 F. Welding even with a wire feed metal that thin is a trick, takes practice and a properly set up wire feed welder, don`t think rosin core wire feed welder will do it

 

[Houndpup Rc]

Got the new one designed from that drawing. Also watched some YouTube on bending metal into cones. I am hoping to get all parts cut out today and maybe start ending but well see hw that goes. I only have access to a stick welder currently so I may have t wait on that too. Any advice on bending/welding sheet metal would be appreciated!

@Patriot Rc (My brother) has done a good bit of welding! You got any tips or ideas patriot?

 

[telnar1236]

Not a welding expert either, but I second the idea that you'll want a mig or tig welding setup - might not be impossible with stick, but it would definitely be harder

 

[Patriot Rc]

Not a welding expert either, but I second the idea that you'll want a mig or tig welding setup - might not be impossible with stick, but it would definitely be harder

Agreed! I think mig would work, but I think tig would work better. I think Stick would just blow holes in sheet metal.

 

[Patriot Rc]

Got the new one designed from that drawing. Also watched some YouTube on bending metal into cones. I am hoping to get all parts cut out today and maybe start ending but well see hw that goes. I only have access to a stick welder currently so I may have t wait on that too. Any advice on bending/welding sheet metal would be appreciated!

Here is a link to a tig welder thats a pretty good price (seems to have some good reviews).

https://www.amazon.com/dp/B0CP3W94K9/?tag=lstir-20

 

[Bearcat]

MY brother has a roller at his school along with a cnc plasma cutter so I'll come with him sometime next week and get those cut and bent and I'll look into that welder because it would be ideal to tig it

 

[Houndpup Rc]

MY brother has a roller at his school along with a cnc plasma cutter so I'll come with him sometime next week and get those cut and bent and I'll look into that welder because it would be ideal to tig it

Noice!!!

 

[Patriot Rc]

MY brother has a roller at his school along with a cnc plasma cutter so I'll come with him sometime next week and get those cut and bent and I'll look into that welder because it would be ideal to tig it

A cnc plasma cutter should make cutting it out easy.

 

[Houndpup Rc]

A cnc plasma cutter should make cutting it out easy.

Just a little😉😂😂

 

[Bearcat]

Just did the final rough draft with the new engine and I think I'm going to stick with this design. Should be going to make the engine soon not sure when exactly tho. Let me know what you think I'll probably start refining it tonight.

 

[telnar1236]

Just did the final rough draft with the new engine and I think I'm going to stick with this design. Should be going to make the engine soon not sure when exactly tho. Let me know what you think I'll probably start refining it tonight.

What airfoil are you using? For flying wings and deltas you want something with reflex or symmetrical since cambered flat bottomed airfoils produce a nose down pitching moment generally