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  #1  
Old 05-23-2018, 02:06 PM
Reaver Reaver is offline
 
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Location: Claremont, CA
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Default Total Engine & Fuel System Weight?

Does anyone have an accurate or close-to-accurate total weight for the engine and fuel system on their RV? (If so, could you share with which components are included and which are excluded, eg fuel lines, mags, engine mount, oil filter, etc?)

Background: we were talking around the hangar of just what would be necessary, and how much technology would need to improve, to get to an all-electric light single engine aircraft. This naturally gave way to wondering what is possible today. So the question we're trying to answer is what the "weight" budget is if we take out the engine, mags, alternators, fuel tanks, fuel lines, oil system, etc. and used that exact weight for an electric motor and batteries. For simplicity we're assuming a FP direct-drive prop.

And just to avoid getting off-topic, yes we know that there is a lot which hasn't been proven about electric motors in aircraft. We aren't planning on doing this, just wondering what the state-of-the-art flight range would be with current technology, and to figure out what improvement factor is needed for battery technology before reaching parity with avgas.
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  #2  
Old 05-23-2018, 03:03 PM
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RV6_flyer RV6_flyer is offline
 
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The engines recommended by Van's Aircraft have their weight published in the Type Certificate Data Sheets. You will need to estimate the weight of all the other stuff. Be advised if the fuel tanks on an RV were to go away, you would still need to add ribs and wing skin back in to complete the airfoil and have a complete wing.

The engine mount is still going to be required even with an electric motor. Some tailwheel RVs use the engine mount as part of the landing gear support structure.
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  #3  
Old 05-23-2018, 03:45 PM
Reaver Reaver is offline
 
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I agree, the new engine would still need a mount. I was asking to ensure that it's counted on the proper "side" of the equation.

Thank you for the link. Now here's hoping someone has weighed all of the other "stuff" needed to make an engine turn......
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  #4  
Old 05-23-2018, 04:11 PM
tgmillso tgmillso is offline
 
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Hey Alexander,
Full marks on heading down this path. I agree that it will be a few more years until a practical range is achievable in an RV, but the fact that the battery specific output is doubling every six years or so really doesn't put things too far away, considering the engineering work that needs to be done beforehand... and how long it takes to build one of these things. From a weight perspective, like Gary said, you're going to need to keep the weight of the tanks. You can't just transfer weight around in the design (i.e. move the fuel weight to the fuselage) because of the increased bending load at the root. Thus I envisage that you will need to keep some weight of batteries in the wing if you are going to use a Van's existing design. Therefore the only saving be the 260lbs of fuel, which can directly be converted to battery weight along the inboard half of the wing. The weight of the fuel lines is minimal.
I'm building a -7, which is almost complete, but I didn't pre-weight many things. That said, an IO-360 weighs about 300lb dry, there's 60lb in a Hartzell constant speed propeller and about 50lb (stab in the dark) of other fruit under the cowl that could be removed including the intake snorkel, air filter, oil, fuel lines, engine baffles and seals, oil cooler, engine controls, sensors, 10 pounds of oil, alternator etc.
Good luck with the project.
Tom.
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  #5  
Old 05-23-2018, 04:36 PM
rv7charlie rv7charlie is online now
 
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That's a *very* optimistic weight for an angle valve engine; about right for a c/s prop, but you need to add for the governor.

I've seen some Lyc FWF numbers in the past, so I'm really looking forward to someone on this forum actually unbolting a fully installed Lyc, including mount, exhaust, intake bits, baffling, oil cooler, lines fwf, etc and hanging it on a scale. I wonder if they will have the courage to post the weight....

I can tell you that a Mazda Renesis (~200 HP) complete with reduction drive, starter, heavy intake system, heavy muffler, radiator, oil cooler, duct work, dual 55 amp alternators, and about 6 lbs of motor mount adapter hardware weighs just over 330 lbs. That includes everything except the part of the mount that's actually attached to the firewall, and it shed about 30-40% of its weight when adapted to the Renesis.

Last edited by rv7charlie : 05-23-2018 at 04:39 PM.
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  #6  
Old 05-23-2018, 04:59 PM
Reaver Reaver is offline
 
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Quote:
Originally Posted by tgmillso View Post
Hey Alexander,
Full marks on heading down this path. I agree that it will be a few more years until a practical range is achievable in an RV, but the fact that the battery specific output is doubling every six years or so really doesn't put things too far away, considering the engineering work that needs to be done beforehand... and how long it takes to build one of these things. From a weight perspective, like Gary said, you're going to need to keep the weight of the tanks. You can't just transfer weight around in the design (i.e. move the fuel weight to the fuselage) because of the increased bending load at the root. Thus I envisage that you will need to keep some weight of batteries in the wing if you are going to use a Van's existing design. Therefore the only saving be the 260lbs of fuel, which can directly be converted to battery weight along the inboard half of the wing. The weight of the fuel lines is minimal.
I'm building a -7, which is almost complete, but I didn't pre-weight many things. That said, an IO-360 weighs about 300lb dry, there's 60lb in a Hartzell constant speed propeller and about 50lb (stab in the dark) of other fruit under the cowl that could be removed including the intake snorkel, air filter, oil, fuel lines, engine baffles and seals, oil cooler, engine controls, sensors, 10 pounds of oil, alternator etc.
Good luck with the project.
Tom.
Good call on keeping the tank weight. CG wouldn't be a concern for a system like this because batteries come in cells that can be put almost anywhere to get the desired CG. Electric engines are lighter than avgas, so some batteries would need to go under the cowl, and you're right that many would also need to be in the wings.

Quote:
Originally Posted by rv7charlie View Post
That's a *very* optimistic weight for an angle valve engine; about right for a c/s prop, but you need to add for the governor.

I've seen some Lyc FWF numbers in the past, so I'm really looking forward to someone on this forum actually unbolting a fully installed Lyc, including mount, exhaust, intake bits, baffling, oil cooler, lines fwf, etc and hanging it on a scale. I wonder if they will have the courage to post the weight....

I can tell you that a Mazda Renesis (~200 HP) complete with reduction drive, starter, heavy intake system, heavy muffler, radiator, oil cooler, duct work, dual 55 amp alternators, and about 6 lbs of motor mount adapter hardware weighs just over 330 lbs. That includes everything except the part of the mount that's actually attached to the firewall, and it shed about 30-40% of its weight when adapted to the Renesis.
I'm going to ignore the prop weight, since an electric engine still needs a prop and there's no reason to re-invent the wheel there. The other reason it's easier to consider a FP instead of CS prop is that an electric engine doesn't have/need the oil line which is required for the governor. So one would cut more weight out of the system by using a FP prop.

btw, I put this in the traditional engines forum because the goal was to get weight on traditional engines, but if a moderator feels it is better-suited for the alternative engines forum a case can easily be made there, too.
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  #7  
Old 05-23-2018, 10:41 PM
tgmillso tgmillso is offline
 
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Hi Charlie,
The weight if for my IO-360M1B, which has a published dry weight of exactly 300lbs (see link below):
http://11hc.44rf.com/manuals/engine-...ec_2-specs.pdf
I concur that my estimate may be a little on the light side for the accessories, however I would rather underpromise and over deliver in this regard. If Alexander subtracts too much weight, then it puts him in an overly optimistic case for how much he can allocate to batteries.
The Hartzell BA 72" constant speed propeller weights exactly 59.6lbs, including the spinner backing plate but not including the spinner itself. I weighed it before I installed it, so that when I remove it, I know how much upwards force is necessary on the prop so that I don't damage the bolts when I undo the last few threads.
Alexander, regarding the propeller weight, I would not assume you would need a propeller of this weight. If you are going with a fixed pitch propeller (eg. Catto, or Sensenich composite), you could save at least 40lbs of weight. The electric motor won't need a beastly heavy prop from an inertial perspective (electric motors run comparatively smoothly compared to internal combustion), and the subsequent CG issue can be addressed by battery placement forward in the engine compartment. 40lb of extra batteries is not to be sneezed at, as you're going to need every pound you can get. Even if you went with an electric adjustable pitch, something like the MT MTV17C/183-59 would still save you 20lbs because of the wood/composite blades. I'd be leaning toward a fixed pitch prop at the outset, as you'll want to keep this project as simple as possible if you wan't to execute successfully. I learnt this the hard way, and have a Subaru EE20 diesel in a crate in my hangar that should be in my aircraft, but there is an IO-360M1B in its place.
Tom.
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  #8  
Old 05-24-2018, 06:54 AM
rv7charlie rv7charlie is online now
 
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Is the M1B parallel or angle valve?
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  #9  
Old 05-24-2018, 08:16 AM
YvesCH YvesCH is offline
 
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Location: Basel, Switzerland
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It would be really cool to have the instant power of a Electric Motor...

I was working as a engineer for the Solar Impulse Project (the plane one who flew around the world only with solar power) and thus thought about building my RV-8 electrically. But as I wanted to fly some cross country I decided to install a IO-360..


But in Switzerland are currently several Projects ongoing to build electrical airplanes such as:

Hangar 55 (Team includes the former CEO and Pilot as well as the former Head of Propulsion for Solarimpulse):
http://www.h55.ch/

Evora:
http://www.evolaris-aviation.com/

Hybrid Aircraft:
https://www.facebook.com/TravellerHybrid/

And from Germany:

Extra:
https://www.aerospace-technology.com...tric-aircraft/
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  #10  
Old 05-24-2018, 02:24 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by rv7charlie View Post
Is the M1B parallel or angle valve?
The IO-360-M1B is a parallel valve engine.
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