Electric part 103 regulations?

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Greg,

When Part 103 was written it was assumed powered ultralights would use a gas engine so the limitation in the regulation is based upon fuel capacity in gallons.  There was no, and currently is no consideration for electric powered ultralights.  So, an electric powered ultralight must comply with the current Part 103 rules, for example:

254 pounds max empty weight

55 knots max full power level flight speed

24 knots max power off stall speed

Extra 24 pounds (278 pounds total) if ballistic chute is installed

5 gallons max fuel capacity (N/A to electric powered ultralight)

So, the question is what about battery weight?  It is included in the empty weight of the ultralight no extra allowance is provided for. 

It would seem reasonable that the FAA would consider an exemption to allow some extra weight for the weight of the batteries. 

Ultralights seem like a great fit for the development of electric powered flying machines, good luck with your project!

Timm

Thanks, Timm, that clarifies pretty much what I already suspected.

I'll ask the EAA guys for some tips and advice as well and report back.  We have a meeting tonight  meeting at Lenhardt's, roughly 25nm S. of Portland). 

I'll also contact our nearby FSDO and (they have an ultralight bird in addition to the 2-seat 25:1 E-430 LSA that's in development) and find out if there are allowances made for up to 30lbs of batteries and the questions of controllers limiting max-level speed (done for ground electric-vehicles.)

I don't see electrics as a panacea, but there's a lot of potential for it to solve many of the problems that attack GA - the issue of leaded fuel, fuel prices, maintenance and reliability, and noise.  Right now the cost of Li-Ion batteries.

Greg

EAA Member since 1992 + ch 105

Please keep us posted here.  I foresee a great interest in an electrically powered ultralight if the range is great enough.

the range obstacle will likely be a biting one. I'm speculating but thicker, higher max-CL airfoils will likely be needed to maintain decent L/D and keep weight down due to spar thickness, necessitating lower speeds, but that's not a given.  We're probably looking basically at motorgliders for smaller pilots for awhile, but my designing hasn't been real-life, just simulated with an eye on reality in XFLOIL/XFLR5, and X-Plane. 

At such low speeds it's easy to get caught into what I've come to call "Reynold's Wrath" too - which means shorter aspect ratio usually.   It's not as bad as high-altitude and/or Mars designing (low Re) yet not kind to thick surfaces.

There's no free lunch.

-GL

[P.S. - Unrelated beta test feedback::  I found the textbox edit problem does not exist in IE. I use Firefox.]

Here's my 2 cents for whatever it is worth.  Is it correct that the max. empty weight is without fuel? Add 5 gallons of fuel at ~ 6 lbs/gallon and you actually have a legal flying weight of 254 + 30 = 284 lbs.  For electrics, the owner/builder should remove the batteries (fuel) for the compliance with the 254 lbs. and then be still legal with the fuel (batteries) installed at 284 lbs.  It's not much but it's 30 lbs of (extra) batteries: how much endurance does that add?  Bob

Bob,

You are correct, max empty weight without fuel is 254 pounds.  The FAA sets the fuel limitation in gallons (5 U.S.) not pounds.  So unfortunately, the way Part 103 is written there is no provision for adding extra weight for batteries.

I like your logic for determining what additional weight the FAA should allow, it would be reasonable for the FAA to issue an exemption for the extra 30 pounds for electric powered ultralights.

Timm

This must come up, there have been a few electrics built. Maybe they're all under 254 lbs with batts, but I'll get around to checking....I totally forgot to ask around last night about the issue, got so wrapped up in other conversation and the impressive Christavia work-in-progress project suspended from the hangar's roof support structure by rope (currently just tube frame, spars + ribs -- yet that's a lot for a plans-built project).

-GL

A more accurate and more useful conversion would be to allow the same amount of electrical energy in batteries as is contained in 5 gallons of gasoline. I don't know what that is or even how much battery weight that would amount to with current technology (no pun intended)- probably more than a 254 lb. airframe could safely lift with an average American (200 lb?) aboard. This value- once carved in stone- would allow any future battery, fuel cell, dilithium crystal, or whatever development to be used resulting in aircraft equal or superior to present gasoline powered ultralights.

9

Great point on equivalent energy vs. equivalent weight. Could get heavy, though - but hopefully battery technology will improve in time and this will be a less-significant issue.

I have heard ultra-thin-film PV's (photovoltaics) are showing progress, too, though I haven't read up on the details.  More viable for lightly-wing-loaded planes vs. heavier, obviously to extend range, given Part 103 is daylight anyways, typically flown in good weather, but would need to be very light to make it viable for part 103  I suspect at 19-20% efficient.