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Old Dec 26, 2012, 09:08 PM
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derp express's Avatar
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FPV with a gas motor

Gentlemen,

I'm considering converting several of my planes to gas so that I can set up wing tanks and extend my range / endurance considerably. I'm wondering if it's feasible to use a gas plane as an FPV rig, of if the vibrations caused by the engine are too severe for the camera/tx?

Regards,


-DE
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Old Dec 26, 2012, 09:27 PM
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United States, CO
Joined Jun 2012
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Totally possible, the vibration can be dealt with. My end goal is the same and have done lots of homework over the months. Basically go for a 1/4 scale or 100+ wingspan ship with a 20cc chipper. Fuel burn is about 8oz/ hr, pop in a 64oz tank for 6-8 hour endurance.
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Old Dec 26, 2012, 10:00 PM
person
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That's more or less my plan as well. Hobbyking has a little 9cc 0.8 hp that would be ideal for a 7 ft span project I've been cooking up for a while. I'm just guessing here, but it seems like if you had your motor hooked up to a rubber mount, that could dampen a huge amount of vibration. But yeah, my end goal is to be able to fly hours on end at a high altitude and then deadstick the thing down on a reserve battery to run the servos. I'm going for a 20:1 aspect ratio...we'll see how that works out. My plan to negate wing-bending tendency is to load fuel toward the tips to more or less neutralize bending stress in flight...works for the airforce, anyway.
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Old Dec 27, 2012, 12:41 AM
fly by night
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Joined Sep 2011
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pretty cool project. If I lived in a desert or open country I would love to do a project like this. One fellow over on FPVLabs has run for several hours on a single tank.
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Old Dec 27, 2012, 10:23 AM
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Might be this guy, super nice Porter!http://fpvlab.com/forums/showthread....6-Porter-build

I have my eye on a 1/4 scale super cub to fly from my mountain retreat, fly around the mountains for hours on end. When at home in the city, well that's what smaller electrics are for.

Ahh yeah, I found it!

65.18 (6 min 30 sec)
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Old Dec 27, 2012, 11:24 AM
BEOWULF
North vancouver, B.C. Canada
Joined Apr 2008
18,597 Posts
Quote:
Originally Posted by derp express View Post
Gentlemen,

I'm considering converting several of my planes to gas so that I can set up wing tanks and extend my range / endurance considerably. I'm wondering if it's feasible to use a gas plane as an FPV rig, of if the vibrations caused by the engine are too severe for the camera/tx?

Regards,


-DE
I use glow engines that are 2 stroke no problem for fpv

Vibrations are not a problem
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Old Dec 27, 2012, 05:19 PM
person
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Joined Dec 2012
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Quote:
Originally Posted by aviatorgeek View Post
Might be this guy, super nice Porter!http://fpvlab.com/forums/showthread....6-Porter-build

I have my eye on a 1/4 scale super cub to fly from my mountain retreat, fly around the mountains for hours on end. When at home in the city, well that's what smaller electrics are for.

Ahh yeah, I found it!

http://youtu.be/Yfrp1DAdvms

Pretty awesome stuff. I guess the question at that point becomes how do you know how much fuel you've got? Are you just staying close enough to glide back to home or doing the world war 1 style "basic math and guesswork"?

Also, am I reading that right? 60 miles from home? O_O

Anyway this is pretty much exactly what I want to do - although I'd want something smaller scale than that. I'm pretty curious to find out what I can do with that little 9cc gas motor hobbyking wears. I know a lot of electrics are balsa, and currently I just build with foam for mine, because I don't have skill required for wood as delicate as balsa. However, since I'm guessing these combustion engine planes are subject to different and/or potentially higher stresses, are they made from a different material? I guess what I'm asking is what's your normal scratchbuilt combustion plane made out of?
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Old Dec 27, 2012, 06:07 PM
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To check your fuel levels, you have a dedicated cam looking at your fuel tank and mark your levels on your tank with a sharpie. Or just make sure your FPV cam has a view of the tank. Not high tech but it's one less thing that can break.

If you watch Picturethis's videos you can see he pans his cam on the left wing to check the tank, but the gas is all sloshing around. To fix this I imagine a fuel tube protruding from the bottom of the tank then going up vertically with 1/4 1/2 ect, marks on it. This is just like a full scale Piper cub fuel gauge.

Fuel gauges are also optional IMO, in the full scale world flight planning is all calculated with fuel burn per/hr. You should always know how much fuel you have at any 'checkpoint' along your route. ie 65% thottle, which equates to a certain engine RPM and fuel mixture depending on altitude and temperate and a certian fuel flow per/hr. So to apply that, he reports 8.3/oz HR @ 40 MPH Cruise, 4800RPM, 3000FT.



Typically they are plywood structurally covered in sheet balsa.
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Old Dec 27, 2012, 06:13 PM
person
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Joined Dec 2012
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Quote:
Originally Posted by aviatorgeek View Post
To check your fuel levels, you have a dedicated cam looking at your fuel tank and mark your levels on your tank with a sharpie. Or just make sure your FPV cam has a view of the tank. Not high tech but it's one less thing that can break.

If you watch Picturethis's videos you can see he pans his cam on the left wing to check the tank, but the gas is all sloshing around. To fix this I imagine a fuel tube protruding from the bottom of the tank then going up vertically with 1/4 1/2 ect, marks on it. This is just like a full scale Piper cub fuel gauge.



Typically they are plywood structurally covered in sheet balsa.

That's a pretty crafty little mechanism. Never would have thought of it.

It makes me happy to hear these things can be built with plywood, since I actually have the skill to work it. I always thought it was too heavy of a material, but combustion engine planes are a different animal, I suppose. Makes me wonder what size of plane I could build around a little motor like this

http://www.hobbyking.com/hobbyking/s..._Ignition.html
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Old Dec 27, 2012, 06:25 PM
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A .40 size trainer plane...1/5 scale or one with about an 70-80in wingspan would be ideal.
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Old Dec 27, 2012, 06:40 PM
person
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Originally Posted by aviatorgeek View Post
A .40 size trainer plane...1/5 scale or one with about an 70-80in wingspan would be ideal.
What would that be made out of plywood? 3-4 kg?
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Old Dec 27, 2012, 06:42 PM
Registered User
United States, MD, North East
Joined Apr 2011
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I have flown fpv with fuel - but the vibrations and potential for engine quitting (and lack of FPV experience) caused me to take a step back and go electric.

I am now back to building a fuel-based long range plane as well, now that I have had about a year of flying electric to gain confidence in my fpv stuff. Fuel is a different animal for sure... But I think it will be worth it in the end.
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Old Dec 27, 2012, 07:20 PM
fly by night
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Joined Sep 2011
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Here is a very interesting thread on fuel engines (well mostly nitro) but they discuss the vibration issue fairly in depth

http://fpvlab.com/forums/showthread....ion-Glow-Plane

and another one - really going for duration and wind handling in this one

http://fpvlab.com/forums/showthread....pable-airframe

I don't know much about fuel, but I do get annoyed by the charging time for big batteries, plus their poor energy/weight ratio. I can' use fuel at my main flying/testing field, but I would love to have a very quiet fuel-powered plane for roadside 'commando missions'. So what is the quitest possible fuel engine/muffler combo out there for models?
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Old Jan 05, 2013, 09:59 AM
Registered User
Australia
Joined Mar 2005
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Main thing id be concerned with is flaming out. If you going to fly gas id take a look at an onboard starter http://www.femamodelltechnik.de/Neue...ist03_engl.pdf
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Old Jan 05, 2013, 01:45 PM
Aerial Operator
United States, CA, Sacramento
Joined Feb 2012
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Quote:
Originally Posted by derp express View Post
Gentlemen,

I'm considering converting several of my planes to gas so that I can set up wing tanks and extend my range / endurance considerably. I'm wondering if it's feasible to use a gas plane as an FPV rig, of if the vibrations caused by the engine are too severe for the camera/tx?

Regards,


-DE
I think one thing to keep in mind is using rubber engine mounts to keep vibration down. I remember seeing a guy that use to sell rubber motor mounts for a .60 size motor and it worked great. Sounds like a fun project.
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