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Motorglider definition...huh?

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BBerson

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Joe Norris at EAA told me 61.31 allows the FAA to grant those 61.31 exemptions when appropriate and only when appropriate.
He said the individual limitation they issue does overrule and supersede all or part of 61.31 as they deem required at that time.
 

jandetlefsen

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requirement for sustained soaring flight.
This is not too complicated to prove. Just look at the sink speed at certain speed ranges. Glider have lower sink speed than what you typically find in thermals, at speed ranges that let you center in the updraft. This is sustained soaring. It's also where your "jetplane in a wave" fails to qualify.
 

BBerson

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There is no requirement for "soaring" in the definition. The requirement is "glide" and the definition does not mention soaring.
A trainer glider may never "soar", yet a trainer has a useful purpose.
I personally, enjoy gliding but am bored with "soaring".
 

Hot Wings

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A bit off topic:

How may motor-gliders, certified or not, have tow hooks as standard equipment?
 

bmcj

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OK, but what if somebody says that they have modest performance goals and tries to register a Volksplane as a motor glider? If there are no criteria, on what grounds does the FAA deny the application?
They may not have any grounds to deny it, but of course every office seems to work a little differently with their own interpretation of the rules. One person licensed a Quicksilver MX-II as an experimental motor glider... he had to push against some fairly strong resistance, but was able to get it done. I think he had to convince them that he often landed with the motor shut off, which is easy to do; we trained a lot of people in MX-II’s and we did a majority of our landings deadstick as a way to emphasize proper glide path judgement. The Quicksilver has neither a long wing nor a noteworthy glide ratio.
 

jedi

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A bit off topic:

How may motor-gliders, certified or not, have tow hooks as standard equipment?
EMG 6 does Most do not unless power is minimal or a sustainer engine. Sailplane type with retractable pod generally do.

For most that do not have the front tow hook it is because the of engine that replaces to typical tow hook position.
 

bmcj

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Believe it or not, I’ve flown a Quicksilver MX from takeoff to landing without starting the engine. Because of the orographic profile of the area, we would get some pretty strong wind gradients when the Santa Ana winds were blowing. We took the plane out to the runway (with lots of people hanging on to the wings and wires), pointed it into the wind and popped the stick back smartly. The sudden AOA change allowed the wind to lift the plane into the air, then inertia and wind gradient allowed me to climb up into the faster air maybe 100-200 feet (?) or more before the gradient tapered off. Once at the top of the elevator ride up, it would start an elevator down, accelerating downward as it descended into the slower headwind. At the top, you had to stuff the stick to the forward stop in order to have enough energy to flare at the end and arrest the downward descent enough to avoid bending the bird.

I think that must qualify as a glider???
 

Topaz

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They may not have any grounds to deny it, but of course every office seems to work a little differently with their own interpretation of the rules. One person licensed a Quicksilver MX-II as an experimental motor glider... he had to push against some fairly strong resistance but was able to get it done. I think he had to convince them that he often landed with the motor shut off, which is easy to do; we trained a lot of people in MX-II’s and we did a majority of our landings deadstick as a way to emphasize proper glide path judgement. The Quicksilver has neither a long wing nor a noteworthy glide ratio.
^ This.

Claims here to the contrary, there are NO concrete requirements defining a homebuilt motorglider as-such. None. Every single FAR and JAR spec cited in this thread is for classifying type certificated motorgliders, not E-AB. As crazy as it sounds, the final determination is going to come down to the opinion of the DAR or FAA examiner doing the airworthiness inspection, and that will not only vary from FSDO to FSDO, but from examiner to examiner, and so on down to whether he had a fight with his wife that morning.

If you can show that you've got a Glider rating on your certificate, have flown sailplanes at least "a bit," and the airplane has "long wings", a starter on the engine*, and generally "looks like a motorglider," you'll have a much better chance of getting your homebuilt declared a motorglider. If you show up with a denied medical on a PPL-ASEL with no "G", and something with short wings and a big motor, the "giggle factor" goes up and you're much less likely to get that declaration (and the privileges that go with it.)

The FAA knows that people want to use the "motorglider loophole" to keep on flying without a medical, or get around the altitude, retractable gear, speed restrictions, and other limitations of LSA. They're generally not fools. If your intent is clearly to go soaring, that's going to show in your cert, your logbook, and the overall appearance and intent of the airplane you're presenting. If your intent is to game the system to get around the medical or LSA requirements, that's usually going to be obvious, too. The case of the Challengers and similar aircraft were enough in the "gray zone" that they gained some notoriety in the back-and-forth to get them declared motorgliders.

So, for an E-AB airplane, span loading, L/D, sink rate, or any other metric are totally irrelevant towards getting it declared a motorglider. If you want to type certficate the design, then yes, JAR-22 is used by the FAA as a baseline but, ultimately, it's going to be up to the certification committee to make the final determination. E-R&D gets a broad pass on limitations, if the proposed design mission supports the notion that the aircraft is intended to operate power-off for significant portions of that mission. This is how things like Scaled Composites' Space Ship One can get a "motorglider" declaration. But E-R&D isn't homebuilding, and gets much tighter scrutiny in other ways.

@cluttonfred, if your intent is to build a self-launching sailplane or glider, make sure you can convince the examiner that you're really out to do just that. People who are serious about it won't have a hard time.

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* A purported ICE or electric "motorglider" without some kind of in-flight restart capability is going to be laughed at. Openly, with a "nice try" thrown in for good measure. Think about it: A motorglider takes off and climbs out, shuts down the engine and goes soaring. Very often, at the end of the day, it's restarted to fly back to the airport. The other point to having the engine on board - for most glider pilots, the main point - is to be able to use the engine for a "save" if the lift dies out, especially in places with poor prospects for an outlanding. If you can't restart the engine, you're not serious about ever shutting it down in-flight, and that's going to be really obvious.
 

Pops

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I have many hours working lift with the SSSC. No electrics on the VW, hand prop only, so I just let the engine idle. One day I flew under a big dark cloud about 4 miles north of my field and watched the ground start dropping away as I circled. Summer time and I just had a Tee-shirt and shorts on and had the windows off and door down and latched for the summer. Got very high and started to get sucked into the bottom of the cloud. Dropped the nose and got away from the monster. It was so cold, I was shivering and wanted to get down quick. Having so much fun don't remember even looking at the altimeter, but took 25 or 30 minutes to get down to the pattern and land and warm up. Just need some longer wings , need to go from 30' to 36'. I have a little 1300 cc, 50 HP , VW engine, 2- 5 gal wing tanks should about do it. Wind generator for the Dist and coil and a recoil starter on the flywheel end for the restart.
 

BBerson

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The majority of motorglider crashes are while trying to restart. I normally land engine off.
 

Speedboat100

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Sink rate isn't always a factor to the purpose of gliding. The essential factor is the intent to use it in unpowered glides.



"example of an extreme experimental glider is SpaceShip One, the winner of the X-Prize for first civilian spacecraft."
First Starfighter was glided to base from 40 miles away when the engine seized.
 

cluttonfred

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@cluttonfred, if your intent is to build a self-launching sailplane or glider, make sure you can convince the examiner that you're really out to do just that. People who are serious about it won't have a hard time.
I was just asking out of curiosity with an eye towards glider-like homebuilt designs like the Souricette. I had no idea what a can of worms I’d be opening.
 

Vigilant1

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The F-104 had a "clean" glide ratio of about 5:1. It was about 3:1 if configured with flaps and gear.

FWIW, I know that in the T-38 in USAF service (a plane with similar glide capability), students were never advised to attempt a dead-stick landing if a safe ejection was possible. Attempt to restart an engine as long as practical (and you'd be trying pretty hard), but don't delay ejection until it is too late.
The approach speeds of the Century Series fighters was quite high, lots of energy. And below some airspeed you'd lose any remaining hydraulic pressure from the windmilling engine. On many of these planes, the flight controls are solely hydraulic, which would make the whole exercise even more "exciting".
 
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blane.c

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I was just asking out of curiosity with an eye towards glider-like homebuilt designs like the Souricette. I had no idea what a can of worms I’d be opening.
"I think" a comprehensive list of the forms needed to be signed off by the government to end up with a legal and flyable experimental amateur built motor glider would be desired? Then figuring out how to get them all signed is up to the individual?
 

Pops

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Let me dream.
Strut braced wood wings of 145 sq' @ 35' 4" span , Single place high wing with my 235 lbs of weight and 2 -- 5 gal wing fuel tanks, for a EW of 475 lbs and a GW of 770 lbs. Use my 1300 cc, 50 hp , VW engine with a fuel burn of 2.75 gph at cruise of 70/75 mph. Need a touch more HP, put in a set of 1600 cc pistons and cylinders with a slightly more fuel burn. Culver wood prop of 54" X 26" pitch. Non- electric, Dist and coil powered by a wind generator on the LG Vee, and a small 5 lb battery , and a recoil starter on the flywheel end as I stated in post 71.
Straight Experimental and fly it LSA. Have low and slow cross country flying and work lift when you want.
 
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