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Old Jan 10, 2015, 08:38 PM
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Evolution EFI Engine on Mugin 3m Plane UAV for cheap long range aircraft?

Hi, I'm very new to this forum and hobby but I've recently gained an interest in making a very long range drone.
From a bit of research if seems like the best is the penguin B, but is way too expensive.

The next best seems to be the Mugin 3m Plane UAV from FPV models. It has a huge decrease in performance, however - changing from over 24 hours of flight for the penguin to only 3 hours. Range is dramatically limited as well.

From what I can tell the reason for this is the engine. If it isn't Ultra efficient from an electronic injection system then flight time dramatically decreases. I don't think it is the airframe that is making such a big difference.

The Mugin plane has less weight , and I believe is approximately the same dimensions. Please correct me if I am wrong.

So, I am curious if the best option would be to go with the Evolution Engines 62GXI with SureFire EFI on the mugin frame. Could this possibly reach 24 hours of flight time? Is there anyway to figure out what to expect with this combination?

The engine I am talking about is:
http://www.evolutionengines.com/Prod...odID=EVOE62GXI
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Old Jan 10, 2015, 10:55 PM
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Alternatively if there are other more efficient engines or plane bodies I'd absolutely love in put on it!
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Old Jan 11, 2015, 03:54 PM
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You're very new to the hobby and you plan on starting with a very long range drone? This is possibly one of the worst ideas. There is so much critical knowledge to learn first before you have a chance of success. What you should do is go to the bank and withdraw approximately $3000, go to the top of a very high cliff, and throw that $$ off the cliff and go home upset and frustrated.

OR, you could buy something like a Bixler and a cheap but good autopilot (like a APM 2.5) and get a basic Fpv system on it and have a blast flying and learning with a system easily capable of around 10 miles (which is PLENTY far enough to get in trouble).

Then, after you get comfortable and used to flying that system, you upgrade to a "long range drone". It will be a much more enjoyable, much cheaper way, to get into UAVs.
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Old Jan 11, 2015, 06:24 PM
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I knew I was going to get an answer like that, and I agree it's a bad idea to start on this level. I probably won't but I that will be my ultimate goal and I currently want to plan and design it, then as I learn more about the issues I can improve on the design and run tests on smaller planes. I'm not really interested in anything besides a long range Ultra efficient self flying plane.

I'll be sure to check out the Bixler and it's autopilot system.

For the mugin, I am intending to have it almost entirely run on autopilot with me doing the bare minimum. Having something like the Panda 2 autopilot hardware/software for it, which seems like a pretty good system but perhaps isn't the best.

http://www.fpvmodel.com/fy-panda2-pa...wing_g384.html

I figure the autopilot discussion is best left to a different thread.

Could anyone at least guide me to one of the best and most efficient engines for fuel usage? It seems like EFI is the way to go, ideally with a four piston engine, though it seems like such a thing does not exist. Additionally having a smaller engine, like 50cc or something is better than a very large one.

What type of engine has the lowest grams of fuel per hour ratio, that still provides enough thrust for flight of a Mugin?

Also if I am running it entirely on software, what benefit do I get from knowing how to fly it manually?
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Old Jan 12, 2015, 03:19 PM
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EFI gives a small reduction in bsfc values -- not as large as you seem to think.
With such a large engine, that plane would be lucky to get to 12 hours endurance.

More important is engine design and propeller-to-engine matching. Typical RC 2 strokes have very old-fashioned porting arrangements that are fine if you just want high power, but lousy if you don't want to shoot unburnt fuel out the tailpipe.
There are also a few 4 cycle options that are much less thirsty .. but much less powerful as well.

I agree with philthy that you should focus on just familiarizing yourself with rc planes and autopilot usage first. You have an RC simulator that you practice with frequently right? RIGHT?? Autopilots don't always behave -- especially when first tuning them. $100 for a good sim is dirt cheap when compared with the time and money wasted with even just one crash.

For research google:
"aerosonde trans-atlantic flight"
"currawong fuel injection"
"3w 28i"
"honda gx-35"
"orbital uav engine"

Slowly slowly catch your monkey.
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Old Jan 12, 2015, 06:16 PM
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Thanks for the reply! I'm sure I'll start out on small planes and cheaper things, but if I can't achieve what I want there is no purpose to go down this road in the first place. I'm not sure how relatable this is for you guys as hobbyists, but whatever hobby I have I can't *just* fly for fun. I like to have a purpose or goal in mind at the very end. When I was into rocketry, my main interest was to make the best most efficient propellant, and rocket design. Launching an estes in some junked-up model of a Saturn five just seems like a horrible waste of money and thought to me. It all about the engineering, learning about specific impulse, etc.

I guess this personality is manifesting itself via trying to figure out the best way to build an ultra long range uav autopilot.


Also that's fantastic to hear that EFI only gives a little reduction in fuel consumption. I saw that the engine used for the pegquin is $16,000+ and figured that is where the magic happened.

Now it appears that perhaps if I used a honda gx-35 that is perhaps tuned to be most fuel efficient at a certain speed I could achieve great flight times.

What is the limiting factor on propeller size? I understand currently that a larger slower propeller tends to give better fuel efficiency than a small rapid one. Would this be so significant that I'd want to modify the rods leading to the tail to allow for a larger propeller?

I could imagine having them lift above and be slightly wider than the current model to help increase the size of the propeller by a pretty decent amount.

Then it sounds like the orbital uav engine is a modification to engines, changing how they get their fuel injected? Perhaps it'd be possible to combine the Honda with the orbital to further improve performance on fuel consumption. From what I can tell it doesn't look like it's add much additional weight, but I need to look into that more.


Would a four or three bladed propeller have any benefit against the typical 2 blades? Seems like it may serve the same function as a much larger propeller? (I'm asking this mostly so I remember to Google it later when I have more time)
Edit: looks like it can be calculated with this info: http://www.nar-associates.com/techni...ncy_screen.pdf
Two blades seems to be the best.

This is good information though, can come up with the best propeller design for speed of plane and weight, plus rpm of motor.
I'll look into the rest of the suggestions later, I'm somewhat familiar with the aerosonde trans-atlantic flight already.

Another question, is there any chance it might be better to get the CAD drawings of something like the penguin or mugin and then rebuild it entirely out of lighter materials, such as only carbon fiber vs fiberglass and balsa?
Obviously it would make it more expensive, but perhaps not significantly if you're doing it yourself and count labor as free, plus would make future repairs easier from developed skills.

Seems like you could pay someone to mill out a wood mold to the perfect dimensions to make the fuselog out of a sheet of carbon fiber, which could b e reinforced by carbon fiber rods and whatever else.
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Last edited by Vesp; Jan 12, 2015 at 07:29 PM.
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Old Jan 13, 2015, 01:05 AM
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Found a $600 EFI for the Honda GX35!
Now this is looking like the best option so far, but still researching a lot of other options. They say it is light but they don't say it's actual weight from what I can see.
http://www.ecotrons.com/products/hon...injection_kit/


So if the EFI makes it more fuel efficient, the 4 stroke has the best efficiency, and it is going rather slow with a large propeller, likely two blade propeller that is designed based on the PDF article and other information... We'd likely get a very nice flight time, especially if other things are improved as well: I am pretty skeptical that the Mugin was designed for the maximum flight efficiency. I wonder how they decided what to shape the wings? "If it flies, sell it!" vs "Wind tunnel results indicate that at X speed, the wing optimized for best lift/air resistance, etc"

Likely could design a wing that, corresponding to the thrust output of the motor/propeller combo would be best suited for it. Though, I am not sure if that is taking it too far at this point.
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Old Jan 13, 2015, 05:19 PM
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Sounds like you are on the right track.

To really answer all the questions you ask requires a degree in aero engineering and a fair amount of analysis.

..but yes, going with a relatively small 4-cycle engine and putting it on an airframe that is relatively large and light is how you maximize endurance. Like I said before, EFI may give you a small increase in efficiency, but don't fixate on it.
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Old Jan 13, 2015, 09:03 PM
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Is it possible to remove much material from the Honda GX35 to decrease it's weight?

Honda GX35 engine:
Install an Ecotrons EFI kit on a Honda GX35 engine (3 min 43 sec)



Additionally, do you think the Honda GX25 engine would be an even more efficient long range motor or is it getting to weak at that point for even flying?
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Last edited by Vesp; Jan 13, 2015 at 10:52 PM.
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Old Jan 13, 2015, 11:58 PM
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After further research it seems like the only reason four stroke engines are rumoured to be more efficient is because of unfair comparisons.

Now it seems like the best motor would be a 20cc to 30cc two stroke engine with an EFI.

Something like DLE-20RA with Ectrons Eectronic Fuel injection kit for two strokes is probably the best.

The wieght difference and the maximum power is very significant.
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Old Jan 19, 2015, 10:55 PM
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I have basically the same attitude as you when it comes to going big or go down in flames... I'm not saying it's the right choice... pretty much I'm saying it's the worst choice. But none the less I'm curious to see how this turns out...

I spent 6k to build my own quadrocopter... from scratch, my own motors selection, carbon fibre props.. the works.. everything from the ground up...

Let's just say thank god I had a fire extinguisher... twice. But keep the drive... I'll be looking out for your posts.
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Old Jan 20, 2015, 05:59 AM
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Thanks! It looks like the Mugin isn't a well engineered plane so I am thinking of maybe trying to reverse engineer a Penguin B, but with a different engine and a made if fiberglass.
I've been looking into a lot - really overwhelming how much there is to this project (which is why I am interested).

Of course half the people at this hobby place keep telling me to just save money and buy one, as if they have forgotten what it's all about.

It looks like ectron has a UAV EFI system. Haven't really decided one an engine: first I need to decide what I am going to do for the airframe.
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