Yeah, I wouldn't trust the guy who wrote that answer, he/she can't even do simple math like $7.125/3.72=1.91$... 😉

Welcome to Av.SE. This question has a couple of issues, not the least of which is the 7 questions within it. But beyond that, this is far more about Space Exploration (and even Drones) than it is about Aviation as defined in the Help Center. I'd suggest focusing the question much more tightly and then posting it on SpaceExploration.SE; I don't think any amount of edits can bring discussions of flying robots on Venus on-topic here.

@RalphJ: for sure it has 7 questions in one but it is not (in my opinion) off-topic since it deals with basic aerodynamics. I'd be glad to answers it (them) as soon as it is corrected.

@sophit: I posted my question on SpaceExploration, as suggested by the moderator. I would appreciate your help. space.stackexchange.com/q/67148/59829

@Zippi: in my opinion you should just split your 7 questions in a couple of separate questions and post them here.

@Zippi: I mean -> post it here on the stackexchage, not as comments but as new questions.

@sophit Thank you. I understood you.

@sophit I posted the first question at the top here. The rest of the questions are separate. Thanks for the explanation.

Well, you know, they flew on Mars with much thinner atmosphere. Pressure (accounting for Temperature) means you must calculate density altitude to determine lift/thrust forces. Also, the atmospheric composition will play a role (mv). On Mars, CO2 atmosphere helped as CO2 has higher molecular mass, 44, vs N2 (28) and O2 (32).

How would high pressure affect? Try a heavier than water submarine design using a rotor for "lift". Denser fluid means slower acceleration, but if there is more lift than gravity, the craft will rise.

@Ralph J I have edited my question. Is it possible to open it to everyone?

I answer in a comment while waiting for the question to be reopened: you can use the same equations which have been developed on earth if you have the same physical conditions. For a rotor, same conditions basically means: 1) Reynolds number of around $10^5$ to $10^6$; and 2) Mach number at the tip of the rotor $<0.7$. To calculate these 2 numbers one needs to know density, viscosity and speed of sound in the venusian atmosphere, values that I unfortunately couldn't find anywhere. Maybe you can try to ask them on chemistry or space stackexchage. If you get those values then we can continue.

I don't think that flying on Venus is on topic here, but if the community votes to reopen the question, that's fine. Right now, it's 2/3 of the way there.

@sophit I have an article that I am currently studying. This article provides the "Mean Standard Atmosphere for Venus (JPL Model)". Оn page 24. Link: researchgate.net/publication/…

@sophit I took the values from the surface (0 km) to an altitude of 1 km, since I consider flying closer to the surface. For a height of 0 km: density 64.79 kg/m3, dynamic viscosity coefficient 3.35*10^(-5) Pas, kinematic viscosity coefficient 5.17*10(-7) m^2/s, sound velocity 410 m/s. For a height of 1 km: density 61.56 kg/m3, dynamic viscosity coefficient 3.12*10^(-5) Pas, kinematic viscosity coefficient 5.07*10(-7) m^2/s, sound velocity 408 m/s.

@Zippi: Thanks for finding those values! Just give me some time to come up with a couple of equation to preliminary size your rotor 🖖