Thread Tools
Dec 26, 2012, 11:54 AM
Registered User
Thread OP
Discussion

Gasoline Multicopter, is it possible?


The thread earlier today about capacitors and battery energy density got me to thinking: is the technology mature enough for a FC to control a fast servo connected to the throttle of a gas engine? If so, then it should be possible to build a quad with 4 engines and a fuel tank for greatly extended range and endurance for FPV. Of course it would also be as loud as the hammers of hell, or perhaps the dental drill from hell!

Has this ever been tried? Does anyone with a greater knowledge of the RC world have any input? My suspicion is that the vibrations would be too much for any camera, but who knows?
Sign up now
to remove ads between posts
Dec 26, 2012, 12:12 PM
Registered User
Why not use one engine for belt drive and go collective pitch? Like 4 tail rotors? That way you only need one servo for throttle and let the fc run the 4 servos for pitch.
Dec 26, 2012, 12:30 PM
Registered User
KAMAX-T's Avatar
yep , what irocjr. said....

Terry
Dec 26, 2012, 12:33 PM
KK Tri Flyer
mattcro's Avatar
You'd need fairly well matched engines with very fast throttle response - and I'm not just talking about the servo. They also need a good wide power band (wide range of RPM at good power output).

A better solution is probably variable pitch props (single-rotor heli style) driven from 1 large motor or individual motors at the same throttle/speed... quad rotor Chinook anyone?
Dec 26, 2012, 12:39 PM
Registered User
I was just thinking of how much of a pain it would be to tune 4 different engines to give equal performance. I would rather not have that aggravation. Lol
Last edited by irocjr; Dec 26, 2012 at 08:32 PM. Reason: horrible mobile autocorrect...
Dec 26, 2012, 01:01 PM
Registered User
Thread OP
Why would the engines have to be tuned equally? We don't power match our electric drivetrains: the FC only cares about movement and attitude, not the power or throttle settings needed to get that attitude. It would seem to me that the FC would just move each throttle servo as required to get the thrust it needed to achieve the result you commanded.

As for variable pitch systems and wacky belt drives, they sound like an expensive exercise in frustration and hyper-complexity. If you could get it to work long enough to be useful at a reasonable price it would be too heavy to fly or you could throw custom titanium/aluminum and carbon at it until it became too expensive to be practical. (I know a little about such systems after a career as an offshore and expat helicopter technician and then flight test mechanic at Edwards AFB.)

I am not talking about re-inventing the wheel, just using off the shelf tech in a different way..... I read here about people with hexes and octos who run pairs of heavy 5000ma batteries and I cannot help but think that a similar weight of Iiquid fuel would give much greater range and endurance.
Dec 26, 2012, 01:10 PM
Triple Tree Aerodrome
heli001's Avatar
It's kinda been done....Thrust vectoring...! The technology is already there...just look at any 3D plane in hover....the elevators and rudder are doing all of the work.....the motor is just providing neutral lift through throttle management.....I'm kinda thinking four DA-150's should do the trick.....!
Dec 26, 2012, 01:26 PM
Registered User
There are better ones, but I like this one.
https://www.rcgroups.com/forums/show...5#post22705146
Dec 26, 2012, 09:38 PM
Registered User
Quote:
Originally Posted by irocjr
Why not use one engine for belt drive and go collective pitch? Like 4 tail rotors? That way you only need one servo for throttle and let the fc run the 4 servos for pitch.
SOMEONE will make this happen...
Dec 26, 2012, 11:01 PM
Registered User
Quote:
Originally Posted by irocjr
Why not use one engine for belt drive and go collective pitch? Like 4 tail rotors? That way you only need one servo for throttle and let the fc run the 4 servos for pitch.

The primary advantage of a quadrotor is that it lacks the mechanical complexity (and multiple points of failure) of a helicopter. If you introduce collective pitch on 4 rotors, you lose that advantage, and you also lose the efficiency of a single large helicopter rotor.

Basically, if you want to use collective pitch, you're better off sticking with a helicopter, IMO.
Dec 26, 2012, 11:27 PM
Use the flybar young Padawan
jombo's Avatar
Now this is interesting , it is definitely doable . No complicated computer controlled electronics . You just put the gyro on the throttle servo . The hard part is the fuel tanks . You can do 2 tanks or 4 (one per engine) . Tuning wont be too bad , just try to make them not stall or bog on fast throttle response by the gyro .
The biggest thing i see is all that smoke , you may loose it in the air
Dec 26, 2012, 11:39 PM
Registered User
It appears variable pitch on quads are right around the corner for the masses. Now it's just a matter of the guys with their ingenious ability to code to make them work for the rest of us.
Dec 26, 2012, 11:52 PM
Registered User
Quote:
Originally Posted by jombo
Now this is interesting , it is definitely doable . No complicated computer controlled electronics . You just put the gyro on the throttle servo . The hard part is the fuel tanks . You can do 2 tanks or 4 (one per engine) . Tuning wont be too bad , just try to make them not stall or bog on fast throttle response by the gyro .
The biggest thing i see is all that smoke , you may loose it in the air
Speaking of fuel tanks, I imagine that fuel sloshing might cause the CG to shift rapidly and unpredictably in a multirotor. I wonder to what degree this might affect the stability of the craft.
Dec 27, 2012, 12:34 AM
Detroit 2-stroke junkie
1320fastback's Avatar
Rite on with one engine.
Have it center mounted with a extended crankshaft to drive 4 belt stacked ontop of each other.
The rotors will be CP and the engine would run in Idle Up.
Dec 27, 2012, 12:39 AM
Registered User
EddieWeeks's Avatar
My friend and I ran a 32 heli engine with a rubber hose connected to a 700 watt brushless motor as a generator.... The wires then went to a 100 amp rectifier, same kind on everyones car... It worked... I ran the .32 engine with an air hose blasting on it, making all kind of racket...
While he connected it to a ESC and then ran an engine with a prop on it... he turned the knob and the prop turned... the alcohol motor slowed down and we sent 100 watts to the props.... Its was so noisy, messy and it was not long before the 700 watt brushless motor started smoking, all for a lousy 100 watts that we could not maintain... I needed 1000 watts... I think a 50 cc Gas twin with a very low KV motor may work but the motor and generator will need serious cooling... With funding I think it could work but on a somewhat larger scale.. maybe 5-10 hp gas…

Eddie


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Multicopter Extras: Optical Flow, Magnetometer, KK Multicopter, AND MORE! Ecibob Aircraft - Electric - Multirotor (FS/W) 2 Nov 29, 2012 03:47 PM
For Sale Gasoline Engine LCD Hour Meter spookyeng Aircraft - Fuel - Engines and Accessories (FS/W) 2 Feb 28, 2012 02:03 PM
Discussion Fastest possible forward flight with multicopter SGsoar Multirotor Drone Talk 28 Feb 18, 2012 11:44 AM
New Product It's a gasoline tax - but we won't call it a gasoline tax... D B Cooper Life, The Universe, and Politics 46 May 14, 2010 06:59 AM
Glow to Gasoline Conversion Possible? Yokozuna Engines 1 Jan 07, 2005 06:20 AM