The construction of the manned Copter FlyingBike continues.
The FlyingBike will be a double copter with a take-off weight of 460 kg, with a payload of 190 kg, a twin-engine (with internal combustion engines), four electronically controlled variable pitch propellers, an electronic flight stabilization system and a parachute rescue system designed for full takeoff weight.
The main advantages of this project are:
- perfect ease of control, which does not require long training and is available to almost everyone (who, for example, can manage a radio-controlled drones);
- significant autonomy, flight range of about 300 km.
Details are on the FlyingBike project website
There are NO drone controller suitable or safe for human use... This said, Arducopter (firmware that runs on the pixhawk) can be personalized to add just about any function you need such as IC engine management as long as you are willing to write some code...
Your project looks cool in theory but mechanical reliability is at a "scary level" in this design... You mention twin engine for safety but will there be redundancy on the:
- 7+ gearboxes to transmit mechanical power
- 4 servos to control rotor pitch (which will need to be massive)
- transmission to connect your 2 engines reliably for redundancy...
There is a good reason why Curtiss-Wright abandoned this design concept...
At 460 KG's (+-1000 lbs) , twin engines and a range of 300 Km's did you compute the power and fuel requirements?
I don't mean to burst your bubble but this project just scares me... Good luck anyway and I hope you can prove me wrong!
In any case - the best proof of theory practice. And besides - until there is no practical experience - all the arguments about "reliability" or "unreliability" - just words or opinions ...
7+ - this is where it came from? I somewhere brought such figures?
And what problems with servo drives? Why do not they embarrass their use in "big aviation"? And what does it mean - "massive"?
Servo machine develops traction more than 16 kg. Where is more to paddle the blades 12 degrees?
If I use EXACTLY in the prototype those servos that I could buy for YOUR money - this does not mean that I can not apply the more reliable ones that are used in aircraft and helicopters.
In fact, it would be right to discuss not the specific details that are used in this first prototype, but the concept.
In addition, the Curtiss was not giving up the idea, but the military. And they were no longer satisfied with the unmasking signs, not the summer possibilities. Because the tasks were different. Do not compare directly.
300 km - approximately ... Same as weight. Weight will strongly depend on the weight of the frame. And the range is from the fuel reserve. At a speed of 150 km / h, the fuel reserve should be for 2 hours. At an hourly rate of 15 liters - about 30 liters of fuel should be enough.
It is clear that the figures are approximate. As long as the prototype is not completely finished - the numbers will change.
And about the "scares" ...But in any case - thanks for the opinion!
OK I had to do the math on power requirements...
The most basic calc that can be used (at least I believe) Would be the classic mechanics calculation for accelerating a body.
Pt=1/2 * mv^2
P: Power in Watts --- > this is what we need
t: Time of acceleration
m: Mass in Kg
v: speed change in m/s
I'm interested in the minimum power needed to hover. So lets say in the experiment we hover our hulky 460Kg beast for 1 second
t: time = 1second
m : Mass = 460 Kg
v: because earth's G value is 9.81 m/s^2 hovering for 1 seconds is exactly the same as accelerating from 0 to 9.81 m/s so v = 9.81 m/s
P*t = 1/2 * m + v^2 ---- > P*1 = 0.5 * 460 * 9.81 * 9.81 --- > P= 22 134 Watts in Horsepower thats: 22134W / 746W/Hp = 29.7 Hp!
Thats 30 HP after all losses and inefficiencies. Now the drawings provided are fairly detailed in terms of the path taken by the mechanical power.. that's how I came up with the number of gearboxes at 7 . Lets work our way of that mechanical chain and calculate efficiencies just for laughs and this ambitions DIYer's sake and safety
I'm assuming that the design in not crazy enough to rely on chains or belts for power transmission so I'm assuming oil filled gearboxes at an efficiency of 95% for: oil friction, bearing and joint friction, and gear friction
30 Hp is the base power required for hovering. In order to actually fly safely, at a sufficient speed and be able to slow its descent and bail itself in case for emergency, it needs a thrust to weight ratio of close to 2 at absolute maximum power.. This is A big assumption on my part based on my hobby and work experience so feel free to correct me. so the base power is now at 60HP
Lets follow 1 arm: 60 HP / 4 arms = 15 HP/ arm
Propeller: The efficiency of a stationary propeller is abysmally low, like 15% or less... with variable pitch, this will probably increase alot so lets arbitrarily put the number at 50% to be very generous. I did read a few articles that explain full scale propellers and small aircraft with variable pitch props can probably achieve that. Once again please correct me if I"m wrong.
15Hp / 0.50 = 30Hp
now the 3 gearboxes : 1st is 90 degrees on end of arm, 2nd is 90 degrees from from arm axle to longitudinal axle, and 3rd is the speed reduction from the longitudinal axle to the engine.
30 Hp / 0.95 / 0.95 / 0.95 = 34.99 HP
Thats 35Hp per arm so 35hp * 4 arms = 140Hp on Engine PTO at maximum thrust. and 70HP just for hovering: I don't know of any motorcycle engine that can deliver that consistently for more that 5 minutes without overheating.. Motorcycles just don't need to do that... It would be like holding your bike on a dyno for hours on... simply not possible.This is a task for a Diesel engine and a 140HP diesel will not fit in the 460Kg weight budget...
Hope this helps..
actually, a modified VW 2.0L TDI diesel could probably fill this role... I admire your tenacity and workmanship Those propeller hubs are quite sexy. You are absolutely right about learning by experience. I have never tried a project of that scope so Cheers to you for actually moving forwards. That's impressive in itself.
In general terms - the calculation of the required power coincides with mine.
But on ... Engine - TWO !!! Therefore, taking two engines with a volume of at least 1 liter, with a power of about 120-130 forces, they will easily provide the required long-lasting power of 70 hp. each, since this is even less than 70% of their maximum capacity.
And as for the "overheating" ...
I recommend to see and try motorcycles in action, and not speculatively. If you gas in place, without blowing, then in that case only the radiator fans are switched on. But in order to "boil" ... Now it's not the 40s of the 20th century ...
And motorcycles such as Kawasaki ZZR1400 and it's not enough that they have a power of about 190 hp, and are designed for LONG movement with high speeds. And really work as an aircraft engine in an INSTALLED mode with good airflow - for such motors in general as a vacation!
Therefore, I think the question of the EXTREME HAPPINESS is greatly exaggerated ...
But in any case - thanks, since you are not indifferent to this topic!
Ok and did you figure out how to transmit the power from the engine to your props?
Also, by 'massive servo' I mean some actuator that can move all four blades under load through their full range of pitch in say 200ms and than do it again over and over. This will be one of the most vital parts of your machine given the naturally unstable nature of multi-rotor craft.
Lastly, your last sentence did not translate well it reads in english:
Therefore, I think the question of the EXTREME HAPPINESS is greatly exaggerated ...
"... I have never tried a project of that scope so Cheers to you for actually moving forwards..."
Many thanks! It's flattering to hear! :-)
The biggest problem, unfortunately, is that many nodes have to do "as possible", and not "as needed." Since the cost of many parts and materials is more than I can afford. I talked about this on the project's website - https://flying-bike2018.com/home/
Accordingly, part of the original ideas and decisions so far had to postpone and use more simple and cheap solutions.
Therefore, I had to resort to IndieGoGo.
But in any case - I will finish this project and raise it in the air!
In transmission I try to use purchased products. Used in cars. This allows to ensure sufficient quality (at least at the stage of the prototype) and eliminates the problems with spare parts.
As for servo drives, modern digital servos provide normal operation at 60 degrees in 0.12 seconds with an effort of 16 kg per centimeter.
More than enough.
Moreover, the greater the weight of the apparatus, the higher its inertia. So 200ms may not be needed.
If the response of the servo is enough to respond in a helicopter weighing about 1 kilogram, then in an apparatus weighing about 500 - even more so!
But this - only in the process of testing will become clear.
I meant extreme overheating.
What can I say?
On the one hand, you are right. On the other - and the other option is NO AT ALL!
Since in addition to using a variable pitch propeller with electronic control - there is no other!
Well again, on one side, what is there to break? And on the other - it's only about money! About what I already said. When we collect the money for the end of the project for IndieGoGo - I can put a servo of a professional class. And, if necessary, duplicate them.
So - I do not see the problem at all! The methods for solving these issues (reliability and duplication) are known to me.
The problem is only in money!
Ok may I interrupt a great conversation between you two? :)
Regardless, Igor - When you are ready to test this vehicle, I would strongly recommend that you use some crash test dummies first of human weight and remotely control it till you figure out if your calculations were correct or not.
As you said, we are not in the 20's right? so there is no reason to put a live human being inside this new invention till you feel its safe to sit inside it. if it crashes the first time, who is going to do further testing and design modifications? :) I hope you catch my drift here. Thanks and keep us all posted on the development.
It's clear!!! :-)
With all my enthusiasm, I'm not crazy enough to immediately climb into the pilot's seat! :-) I want to go to heaven, but it's better not as a soul, but as a whole, on my flying motorcycle! :-)
Of course, at first there will be flights with a weighted mannequin. Since the adjustment and adjustment of control systems takes time.
Since I have problems with project financing, I do it in a simplified version - one motor while instead of two, there is no duplication of control channels, there is no parachute rescue system.
That's why I'm asking for help on the IndieGoGo website!
And according to the results of tests of this prototype, changes and clarifications will be made!