Need help building a large quadcopter

Discussion in 'General Discussion' started by Ikram, Jun 30, 2018.

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  1. Ikram

    Ikram New Member

    I am a software engineer and don't have much knowledge of mechanics. I want to build a quadcopter that can lift about the wieght of a person say 100 kgs. I am thinking of to use a 125cc bike engine for power and gearbox for related speed change requirements. So the total weight of the drone could be around 150 KGs including that pilot I talked above.
    I want to know
    Will it be possible practically to build in such a way?
    Would the engine be able to provide required speed and RPM?
    What size of propallers should be?
     
  2. RENOV8R

    RENOV8R Well-Known Member

    Do you have a budget that may exceed $75,000-$100,000? (Conservative estimate)
     
    mozquito1 likes this.
  3. LoneRCRanger

    LoneRCRanger Well-Known Member

  4. Tentoes

    Tentoes Well-Known Member

    Well, let's see... When I was into rotorcraft, a 90hp gyrocopter engine produced about 300 pounds of thrust when we tied the gyro to a scale. 4 25hp engines might lift your pilot and machine, but won't have much power left to stop a descent before hitting the ground. 25hp is about 19 kilowatts.

    The biggest problem is going to be "engine out performance." What do you do when you're flying along and something breaks? One of those ballistic parachutes might be a good idea.
     
  5. LoneRCRanger

    LoneRCRanger Well-Known Member

    There were similar problems with developing the OSPREY VTOL. Engine power coordination was the main problem. That project cost what, $175 Million Dollars?:
     
  6. Ikram

    Ikram New Member

    parachutes can be used in failure. So what do you think about 150 hp engine? Will it be enough to perform all the flight operations?
     
  7. RENOV8R

    RENOV8R Well-Known Member

    How the heck are we supposed to know? This is a quadcopter forum, we play with little toys where thrust is measured in grams!
     
    mozquito1, Ikram and dragger201 like this.
  8. wafflejock

    wafflejock Well-Known Member

  9. wafflejock

    wafflejock Well-Known Member

    Last edited by a moderator: Jul 21, 2018
    Ikram likes this.
  10. dragger201

    dragger201 If it ain't broke, don't fix it??? You kidding?

    Yeah, I don't think eCalc is gonna be any use for this one.................
     
  11. wafflejock

    wafflejock Well-Known Member

    I tried it for a few minutes there and closest I could find was a 7kw motor (big turnigy motors) and seems like 6 or 8 of them, managing the heat on the motors would still be a major issue.
     
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  12. Tentoes

    Tentoes Well-Known Member

    Well, that's about 9.3 horsepower. Heat of the motors? No problem, just let the prop wash blow on them.

    Um. My biggest quad is 300 grams.
     
  13. Dugdog47

    Dugdog47 Well-Known Member

    Is using 4 chainsaw motors an option?
     
  14. wafflejock

    wafflejock Well-Known Member

    Just remembered Colin furze on YouTube made a "hover bike" apparently used two paramotor engines.
     
  15. mozquito1

    mozquito1 Well-Known Member

    Ha too big for this site but a fuel engine is not the way to go. At least study the police bikes in dubai a bit. Or the ehang.
    Stupid money. I think this is the wrong site.
     
    Last edited: Jul 20, 2018
  16. Ikram

    Ikram New Member

    Ehang's motors provide a commulative horse power of around 143 hp and is able to lift and fly around 700lbs(including its own). If I use a heavy bike engine worth of 150hp of moderate wieght, why should it not not be able to fly around 650lbs. Shouldn't it?
     
  17. RENOV8R

    RENOV8R Well-Known Member

    You are not listening. We play with toys. We are not engineers. How are possibly able to tell you if a homemade death trap is able to carry around Shaquille O'Neil?
     
    Dugdog47 likes this.
  18. Dugdog47

    Dugdog47 Well-Known Member

    How would one motor be able to run four propellers lol?

    Now four chainsaw motors might just work if you hooked the throttles up to servos and have the servos controlled by a flight control board.

    Can you imagine how totally AWESOME four chainsaw motors would sound flying through the air lol?
     
  19. wafflejock

    wafflejock Well-Known Member

    I'm a software engineer (web dev, but have CS degree) as well but that doesn't really cover the electrical or mechanical engineering you'd need to be capable of to pull this off. Regarding the single drive supplying power to multiple rotors I imagine you can do this with some sort of continuously variable transmission but still separate throttle controls would be better. Even if you have separate throttle control the response time from activating the throttle to the power being delivered is going to be slower with gas powered vs electric so quick adjustments to RPM that most of our toy/hobby grade stuff basically depends on for stable flight won't be possible you'd need to either adjust the PIDs to account for delays in the mechanical systems or develop that yourself.

    If you are really going to pursue this would suggest you start at a much smaller scale to work out problems that will be amplified when you scale the thing up and take it piece by piece instead of trying to jump into the deep end with no experience.
     
  20. Dugdog47

    Dugdog47 Well-Known Member

    The reason I suggested chainsaw motors is because the two stroke engines are fairly responsive and just might work but this is just an idea to me and just throwing stuff out there lol. Of course it would take some trial and error on a smaller scale and cost some serious $$. A single engine with a variable transmission has been tried with various levels of success but four independant motors is a proven design that works on a larger scale.
     
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