Electric homebuilt aerobatic glider

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bmcj

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This comment reliably comes up every time someone mentions the concept of a motor glider. You'd think in an aviation related forum people would know that a glider isn't just a regular plane without engine.
Sorry, my comment was offered in fun with a wink and a giggle. Over my many years of flying, I have flown powered planes (jet and prop), gliders, motorgliders, ultralights, hang gliders, and even rolled and parachutes (less like flying, more like falling with style), so I actually understand the nuances between airplanes and gliders. The two I haven’t flown is balloons and Gyrocopter, but I hope to eventually add Gyrocopters to my logbooks sometime in the future.
 

jedi

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I've always liked classic German gliders from the 20s and 30s and 40s, especially the aerobatic ones. I had a notion lately to come up with something along those lines, except: easier to build and with electric self launch capability. Enough juice to get up to, let's say, 4000ft , shut down and aerobat your way back down. No great cross country requirements, nor speed. Just unbreakable in the air, cool classic lines (probably open cockpit and easily removed wings, by one person. Ought to feasible even with current battery technology.

Glider plans seem to be thin on the ground and I certainly can't find anything with these kind of lines. The motor could always be retractably mounted on a pylon . Anything even remotely like this out there?

View attachment 128845

My sincere apologies for going way too far afield from the OP referenced above.

In an attempt to get this conversation back on track I think it would help to define any material limitations. If labor intensive wood construction is selected there should be several examples to copy. If carbon fiber composite is an option the result should be fantastic but a bit expensive. Aluminum and aerobatic implies fatigue issues.

To PTAirco. Do you have a preference or know of other options, steel tube for example.
 
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jedi

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If low cost and ease of construction is dominant I would look to the
Bailey-Moyes Tempest ultralight glider for some inspiration.

If you really want the the 30’s look the design is there to inspire or copy as you wish.

In carbon I don’t think you could find a better example than the electric Windex 1200C redrawn as you wish to look 30ish.
 
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Peterfyg

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Maybe the original 12m Silent motorglider converted to electric might work, though dont know about the aero potential, but the fuz seems to be the same as the current one they fit FES to. I remember watching a sizeable electric RC sailplane. Short burst of power during thesequemce made a huge difference to the flight duration, maybe it could be more than a straight climb.
There are large scale plans for the Lunak around 😁/
There are a couple ow winches in Europe that can do 4000'
 

radfordc

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So if my Hatz biplane identifies as a motorglider, I don't need a medical to fly it? 🤔
Not so sure about your Hatz, but Bert Rutan's original Space Ship I was registered as a motor glider. Glide ratio was probably less than a Hatz
 

PTAirco

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Not so sure about your Hatz, but Bert Rutan's original Space Ship I was registered as a motor glider. Glide ratio was probably less than a Hatz
I thought a minimum glide ratio of 20:1 was required to qualify as a motor glider in the eyes of the FAA?
 

Tiger Tim

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I suspect finding the line between an E-AB airplane and motor glider is like finding what makes a pot differ from a pan.
 

PTAirco

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All the FAA rules for gliders only apply to aircraft with a type certificate (ie, factory built). There are no standards for experimental motor gliders.

So how would that work regarding flying with no medical? If a type certified motor glider needs to demonstrate at least a 20:1 glide ratio to enable it to be flown with no medical, surely the same applies to experimental motor gliders. Otherwise you could claim your Stolp Starduster or RV6 is a motorglider and forgo the hassles of medicals.
 

jedi

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So how would that work regarding flying with no medical? If a type certified motor glider needs to demonstrate at least a 20:1 glide ratio to enable it to be flown with no medical, surely the same applies to experimental motor gliders. Otherwise you could claim your Stolp Starduster or RV6 is a motorglider and forgo the hassles of medicals.
True! And many other benefits also.
 

radfordc

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So how would that work regarding flying with no medical? If a type certified motor glider needs to demonstrate at least a 20:1 glide ratio to enable it to be flown with no medical, surely the same applies to experimental motor gliders. Otherwise you could claim your Stolp Starduster or RV6 is a motorglider and forgo the hassles of medicals.

So you're saying that the FAR's should all make sense and be rationale?

A guy named Chuck Shrivner fought a battle with the FAA to get his Quicksilver MX II ultralight trainer registered as an experimental motor glider.

Here is the documentation....
 

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radfordc

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Spaceship I is a glider, too.
"SpaceShipOne has a standard "N" registration number; but it is licensed as an experimental glider. There was a huge bureaucratic hassle trying to license it as a rocket powered spacecraft, which they just sidestepped by calling it a glider. When asked if it had a yaw string; Melvill laughed and said that lacking a center window, we could not use a Yaw string. The registration number is N328KF, where 328K is the number of feet in 100km, the official edge of space. (White Knight'the aircraft that took SpaceShipOne aloft'is N318SL - Burt Rutan's 318th design."

 

radfordc

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These are old examples. I don't know if you could do the same today or not? The FARs haven't changed as far as I know, but it's up to the DAR/FAA to issue the experimental certificate.
 

addaon

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Yeah, I think that’s what people are missing here. The CFRs, like all laws, are interpreted by humans, not machines. The fact that it’s technically possible to register something that doesn’t meet the standard definition of a glider as a glider is a major boon for us — it allows true experimentation, shifting the boundaries of what’s possible. As an example: a microlift glider, with a < 200 ft/minute sink rate, might be so slow that it doesn’t hit 20:1 glide, but is certainly a glider, though not a sail plane. We can build that, and register it, and even make it self launching, and find out if that’s the future of gliding.

But folks seem intent on abusing any flexibility in the rules for their own convenience. And I get it — hacking is cool, and both written laws and bureaucracies can be hacked. But this is also how we as a community lose privileges, such as the Part 103 training exemption.

DARs (and FSDOs) are the enforcers here. If you want to do something a bit off the beaten path, make sure they know what you want to do, and why. If you’re turning off the engine during flight, register as a glider — it reflects the intent of the rules. If you’re just worried about medicals — we have LSAs and Part 103 for that.

Put your cleverness towards designing and building a plane, not towards ruining things for the rest of us.
 

BBerson

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There isn't any 1:20 rule for type certification. Basic Glider Criteria doesn’t even mention glide ratio, it only says the climb angle should not be less than 1:17.
The definition of “self-launching” glider is “based on the premise that power is intended to be used for takeoff, climb, and intermittent use thereafter. (ref. Basic Glider Criteria)
 
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jedi

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If you want to know the limit of what is possible contact your local DAR and ask. Not all DARs can or will sign off a glider. All DARs are not created equal. The DAR needs the authority from the FAA to do the inspection.

Anyway, that is what I was told by an unofficial source and I know it is nearly impossible to get the FAA to sign anything off.
 

PTAirco

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There isn't any 1:20 rule for type certification. Basic Glider Criteria doesn’t even mention glide ratio, it only says the climb angle should not be less than 1:17.
What does "climb angle" mean in relation to a glider?
 
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