How to properly design a VTOL/ADAV helicopter-plane?

[Christophe]

Here I am calculating the comparative drag forces: the 4 m cubic trailer at 130 km/h a priori is 160 kg of drag according to the first simulation that I have just done! It's huge and that's why we don't see many at these speeds!

But Macro will tell you I've already seen it and it's a good tool!

ps: and an additional drag of 160 kg at 130 km/h is an additional theoretical power to be provided of 1600 * 130/ 3.6 = 58 additional Watts or 000 hp! In other words, a 78 hp car cannot travel at 110 km/h with such a trailer. I will refine the calculations...

[Remundo]

the aerodynamic drag force is 1/2 ro S Cx v²

if we take the Cx = 1 of a block, v = 36 m/s, ro =1,3 kg/m3

we arrive at 842 N

The software estimate seems a little high, but not crazy.

at this enormous speed, it represents a power of 30 W, or about 400 hp

but it is doable with a car of 100 hp and more.

[Christophe]

the aerodynamic drag force is 1/2 ro S Cx v²

if we take the Cx = 1 of a block, v = 36 m/s, ro =1,3 kg/m3

we arrive at 842 N

The software estimate seems a little high, but not crazy.

at this enormous speed, it represents a power of 30 W, or about 400 hp

but it is doable with a car of 100 hp and more.

Uh... you did your calculation for 1 square meter Remundo... My trailer is 1.4 * 1.4 = 2 m² of front surface and we therefore obtain exactly the same result in order of magnitude...

So a 110 hp car will have trouble going up to 130 km/h with such a trailer...it's possible but it will take a lot of km...on the flat...uphill it will be 110 km/ h big max...! (a single car needs at least 30 to 40 hp for 130 km/h)...

ps: a rectangular parallelepiped has a slightly better Cx than a cube...I'm sending you a PM because I knew how to calculate them for the 3 cases

[phil59]

Attention, I specify right away, this is not a criticism to drive anyone!

But, can we individually make a calculation, with on one side, and on the other the car?

Isn't it a rolling set, where the car is already creating something behind it?

With the ion, which has (was) 100 km of autonomy, "I liked", being "sucked" by a truck, 5m behind, because my autonomy was greatly increased.

It's just a remark, put with gloves! but certainly no more than that!!!

[Christophe]

But VTFF with your tractor vehicle! It has no interest in the context ofa comparative study between 3 different forms of trailer !!

You don't understand what in these words and this principle of comparison?

And if you want to find out and get results, open the yellow pages, a fluid design office is at least €500 excluding tax per day so prepare your checkbook!

I just gave all the results to Remundo in MP... he deserves them, not you...

[Remundo]

the aerodynamic drag force is 1/2 ro S Cx v²

if we take the Cx = 1 of a block, v = 36 m/s, ro =1,3 kg/m3

we arrive at 842 N.

Uh... you did your calculation for 1 square meter Remundo... My trailer is 1.4 * 1.4 = 2 m² of front surface and we therefore obtain exactly the same result in order of magnitude...

so totally okay for 2 m², that brings me to 1684 N, or around 170 kg in mass equivalent.

my literal calculation and the simulation are very consistent

I missed this data.

[Macro]

I didn't start it!!!

When you have 2 mins. You will find out which of us threw the first insult at the other. You'll find me the moment I said your job was shit....
About your trailer. I even think I helped you a bit at the start, concerning for example the length of the drawbar, the condition of the axle and with looking at some photos, I even found old repairs to be redone... Concerning aerodynamics. .. I don't know anything about it... On the other hand in such a project... I don't understand why you didn't do physical measurements before modification to quantify your improvements... Excuse me for the bars roof .... Indeed it was small ...

[Remundo]

So to get back on topic...

Let's get acquainted with the latest quadcopter technology

it's very easy to fly, very developed, very stable, and not too expensive!

for 100 € you have an entry-level model.

One can imagine the extrapolation to a model that carries passengers. Apart from strengthening the engines, the algorithms and the control can remain the same.

Lots of intelligence, responsiveness and fast automatisms at your disposal, a 4 year old kid is able to move a quadcopter.

In my opinion in a good VTOL/ADAV, you need a quadcopter structure switchable to airplane mode.

But if a rotor breaks or fails, there is no redundancy and the drone falls. This poses a problem if you carry passengers!!

Some multirotors have 8 motors and algorithms that compensate for returning to the ground smoothly. Debated here eg

Lift is better.

If we push the multirotor to the extreme, there is a taxicopter project with many propellers, called "VOLOCOPTERE"

But I don't think we should go in this direction in an ADAV/VTOL concept!

[Remundo]

So today, here are some concepts or prototypes of VTOL/ADAV

This interesting first with a central propeller surrounded by an aircraft fairing

This one has 3 rotors including 2 tilting ones (on the wings)

Finally this one of a large capacity American VTOL

[Remundo]

Some thoughts on the best aerodynamic shapes for a subsonic aircraft

Subsonic light aircraft ideally revolve around a streamlined body, here are some examples from the site Mauboussin planes

For a small plane, the model Alerion

avion_mauboussin_alerion_m1h_solo.jpg (157.48 KiB) Consulted 560 times

For a slightly larger aircraft, the model halcyon

avion_mauboussin_alcyon_solo.jpg (163.96 KiB) Consulted 560 times

In the category of small "private jets", we can also cite the Piaggio Avanti which had been particularly studied on the aerodynamic plan

piaggio_avanti.png (507.83 KiB) Viewed 560 times

The placement of the propellers is generally:
* at the nose tip for small planes
* at the wingtip for medium aircraft
* mid-wing for larger aircraft

Note that for the Avanti, the placement of the propellers has been debated; these propellers placed upside down, at the tail of the aircraft and close to the fuselage have a degraded efficiency, even if overall the aircraft obtains quality performance thanks to its fine aerodynamics and powerful turboprops.

But the Avanti wanted to keep a large volume and good comfort for the passengers and deliberately made the choice to deport the wings and the propellers to the rear.

A note about the Alcyon, which has no propeller at the tip of the nose, nor "duck-plane" wing, I wonder about the pointed shape that was chosen, which is not necessarily the most aerodynamic. Perhaps we are falling back into "design" coming from an erroneous "perception": no, the sharp wedge is not the best way to slice through the air. Air is not wood.

Here is to fix the ideas, disregarding the propellers and the wings, the forms and their Cx from French Wikipedia

Cx_differentes_formes.png (63.47 KiB) Viewed 555 times