New glider design

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gtae07

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The consensus might surprise you: L/D in the 30-32:1 range, easily trailerable, self-launching.
That doesn't surprise me in the least. Someone looking for "an 'adequate' sailplane/motorglider for casual/fun-flying use" is looking for ease and convenience of operation, not maximum performance.

I got my glider rating this past April at a commercial glider school, and enjoyed the hell out of the flying*. Unfortunately I have not yet had a chance to log any more glider time. We have a "local" club ~40min up the road that I'll probably eventually join, but so far I just can't justify it.
- They only operate on weekends, and until about a month ago I worked weekends.
- Being a club, you need to stick around and help out/participate. That's not inherently a bad thing, but what it translates into is the expectation that if I'm going out there, I'm out there all day and most of it won't be flying--and that's just not going to work with my current family situation. I can't justify a full day at the airport every week (or every other week) with a young child at home, an unfinished RV project, and other commitments, just to get an hour or two of flying in.
- They have the US-standard aerotow model (read: high operating costs, extra manpower requirements).

My interest in gliders is similar to the reasons I enjoy taking a small sailboat out on a lake. I'm not interested in competition and though the badge system holds some interest I'm primarily just looking to stay local and have fun. A self-launch glider would free me from the fixed time window and the necessity of having others standing around just to get me in the air (and probably impatiently awaiting their turn), and makes operation from "regular" airports a little easier. Easy trailerability has obvious advantages.


I started taking OP's survey but realized so many of the questions I don't have the experience to be able to answer--and it seems primarily geared towards competition flying, not a fun/recreational flying that I'm looking for.


*unfortunately I had very limited opportunity to do any thermaling/soaring; the weather was less than desireable for that and admittedly the school is much more a ratings mill than a soaring school so they didn't really do any practical instruction on the matter
 

PiperCruisin

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Hi, you need to get some sailplane experience to see if soaring appeals to you. If you are not likely to ever fly engine off, a motorglider is not the right plane for you. The long wings are a pain to deal with on the ground and the c-c ride is bumpier and slower than a c-c oriented LSA. There are some MG that can be flown at spans matching the type of flight; with long outer wing panels for soaring or with shorter span tips.
I agree with blane.c. I have glider experience. The tow is expensive and a bit of a logistical inconvenience. Longer wings means that for any design, the outer panels need to be removable or foldable to be practical. A TMG can soar or tour and is relatively efficient. If you don't like the bumpy conditions, fly in the morning.
 

User27

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...
The consensus might surprise you: L/D in the 30-32:1 range, easily trailerable, self-launching.

IMHO, 18m is more for those who are interested in competition, even if it's just the OLC. Nothing at all wrong with competition, but it's not why everyone flies. I have zero interest in it, myself. My interest is in a touring motorglider, and the ESA "consensus" glider would be perfectly adequate for me, and it can certainly carry an engine and do 30:1+ at 13.5m span.
I understand why some people might feel that way, from my perspective that is just throwing away performance. I don't fly many competitions, and only then to fly in an organised soaring week. I enjoy the challenge of being set a task on a day when you may not have even gone to the gliding club - and then getting around. But at 30:1 (against around 50:1 for an 18m glider) performance becomes quite limited on windy or weak days which limits your enjoyment. I would rather have a self-sustainer engine (electric by preference) as the compromise for a self launcher is too great for me. The minimum performance that is really useful is the good standard class bench mark of 1:42 at around 60kt. Ideally with the ability to carry water to increase wing loading to increase cruising speed on a strong day. I favour flaps because they just the glider more efficient over a wider speed range, accepting the greater complexity. I want to be able to fly 300 to 500km on a good day with a good chance of getting home without taking (m)any risks and in relative silence without an engine running. I'm currently rebuilding a Ventus 2CT, it meets all my goals and is also not too difficult to rig or handle on the ground. The price of these gliders in Europe is now north of $100K, even though the design is 25 years old, and appreciating slowly. To me that reflects their value to those who are interested in a good day out soaring without too many compromises. A 30:1 motorglider doesn't really hold much attraction for me. But I also understand there is no one answer for all!
 

Topaz

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I understand why some people might feel that way, from my perspective that is just throwing away performance....
That's the exact same argument that was used for 15m ships 30 years ago as being the only "serious" soaring and the same one will be used for the 23m ships fifteen years from now, when anyone flying 18m gliders will be "just throwing away performance."

In your case, since what you describe is "... enjoy(ing) the challenge of being set a task on a day when you may not have even gone to the gliding club - and then getting around," you're still competing - just with yourself. When I go up, I don't have a goal or a bar to surpass at all. I just enjoy flying. No more, no less. I also want to do some traveling in my airplane, and that means a motor for cruising, even if I also have the ability to turn it off and soar, also. A 50:1 pure sailplane, or even one with a sustainer, is worthless for that.

Different worlds. If yours is what you enjoy, then I have no problem with that. Try to judge the worlds of others a little less harshly. Different people value different things.
 

mm4440

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Many years ago Dr. Eppler wrote an article identifying 18m as the sweet spot for competition sailplanes in terms of performance, handling in the air and on the ground and cost. I think it was pre carbon which changes things somewhat. I don't remember the exact figure but cost was an exponential factor with span(2-5). I still find that difficult to understand. Any thoughts?
 

Topaz

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Any notion of a "sweet spot" or "ideal" span is going to be entirely subjective, and depend entirely on what kind of soaring the pilot wants to do. 18m certainly isn't anywhere near optimum for paragliders or hang-gliders, for example. Nor for trainers, nor for micro-lift gliders. I personally knew someone (now deceased, unfortunately) who got all three of his FAI Diamonds in an SGS 1-26D, which certainly isn't 18m. In fact, it's not even 13m.

For pure competition-style flying, maybe 18m is "ideal," But if that's so, why do we have an Open Class?

In my personal experience, the definition of "ideal span for serious soaring" seems to be "The span of the glider I have that's a little bigger than most of the people I fly with." Kinda like how instrument stacks on powered planes aren't "serious" until they're a little bigger than the other guy's.
 

mm4440

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A mix of subjective and calculation taking practical restraints into consideration to get to a satisfactory, buildable, etc. design. Span is good for performance. My idea to to increase span and performance while increasing buildability, ground handling ,and trailer-ability is multi-panel wings With ~14' panels. I am even considering a folding or removable tail boom. A modular design that can be built in section in a modest building space and fit on a more modest size and easier to tow and store trailer than the typical monsters.
 

Victor Bravo

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There are several different types of "non-competition" soaring, and several ways to define and enjoy performance.

When the 13.5m Sparrowhawk came out, it promised a whole new sport of "micro-lift" ultralight soaring, where you could accomplish things that even the open class ships could not (because they weighed more and had zero maneuverability). The whole micro-lift thing, being able to stay aloft at 9AM on morning mouse farts, and ridge soaring on manure piles that only R/C gliders were flying... you would be just losing out on all the fun if you "only" owned a Ventus or a Nimbus 4.

If you have a ratty SGS 1-26 tied down outside, and all you have to do is un-tie the ropes and hook up the tow rope, then from your point of view the guy with the full-tilt racing Ventus is "giving up half the soarable days" if he's too lazy to pull it out of the trailer, or doesn't have a crew, etc.

When I was lucky enough to have that full-tilt Ventus 16.6 meter racer a million years ago, I looked down my nose and past the dog-s**t on the bottom of my shoes at the guys floating around the local area in the 1-26. I laughed my ass off at the humble guys who were boasting about making a 200mile triangle in them. Today, I'd be thrilled to have that 1-26 tied down and ready for me to just fly around the local area, or plod around a 50 mile triangle.

Matter of fact, just today I signed up for membership in a local club so I could have access to their "high performance" 1-34!
 

John.Roo

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Actually is possible to find on market a lot of beautifull gliders practically in any requested range of performance. New or used...
Even self launch or FES versions are available (not that many and of course for much higher price).
When money is not a problem to buy "orchids" with L/D 1:50 and participate on serious competitions.

However I am personally also missing category descripted by Topaz.
"L/D in the 30-32:1 range, easily trailerable, self-launching".
And I would add - "able to cruise and easy to fly with safe stall characteristics".

- L/D 1:30-32 means no need of large wing span
- shorter wings = lower weight = easier manipulation (dismantling to a trailer etc.)
- self launching means freedom to use it whenever I want to go to fly
- friendly and safe flight characteristics are important for older (or very young) pilots
- fun factor - "... enjoy(ing) the challenge of being set a task on a day when you may not have even gone to the gliding club - and then getting around".

I know, I know... last argument has been used to explain necessity of much higher performance (1:40+). But who says that this performance is not achievable? Before you blame me for contradiction in terms I would like to explain that electric propulsion allows to use "sponzored L/D".

Small one seat glider needs 5 kW of power for horizontal flight. With added power of 2-3 kW you could increase your L/D to higher number than 1:30(32). "Hardcore glider pilot" will may call it "cheating". I say - that is energy management :cool: And this "addon" can add new "dimension" to beautifull world of casual gliding.
 

mm4440

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There are several different types of "non-competition" soaring, and several ways to define and enjoy performance.

When the 13.5m Sparrowhawk came out, it promised a whole new sport of "micro-lift" ultralight soaring, where you could accomplish things that even the open class ships could not (because they weighed more and had zero maneuverability). The whole micro-lift thing, being able to stay aloft at 9AM on morning mouse farts, and ridge soaring on manure piles that only R/C gliders were flying... you would be just losing out on all the fun if you "only" owned a Ventus or a Nimbus 4.

If you have a ratty SGS 1-26 tied down outside, and all you have to do is un-tie the ropes and hook up the tow rope, then from your point of view the guy with the full-tilt racing Ventus is "giving up half the soarable days" if he's too lazy to pull it out of the trailer, or doesn't have a crew, etc.

When I was lucky enough to have that full-tilt Ventus 16.6 meter racer a million years ago, I looked down my nose and past the dog-s**t on the bottom of my shoes at the guys floating around the local area in the 1-26. I laughed my ass off at the humble guys who were boasting about making a 200mile triangle in them. Today, I'd be thrilled to have that 1-26 tied down and ready for me to just fly around the local area, or plod around a 50 mile triangle.

Matter of fact, just today I signed up for membership in a local club so I could have access to their "high performance" 1-34!
Hi VB, Sparrow Hawk was not a micro-lift sailplane. It was a UL weight conventional wing loading sailplane. The micro-lift sailplanes were the Carbon Dragon and Danney Howell's Light Hawk. Sailplanes that could really fly with the soring birds. Bruce wrote that the magic number is < 1'/sec min sink and you can stay up almost any day. If you can combine that with a reasonable L/D and redline speed you would have quite a soaring machine.
 

Hot Wings

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I laughed my ass off at the humble guys who were boasting about making a 200mile triangle in them.
I remember reading some posts on RAS from a guy with similar opinions in the distant past...................life does tend to change us. :beer:

I would like to explain that electric propulsion allows to use "sponzored L/D".
I like the term 'sponsored L/D'. 👍 It isn't limited only to electric and is an option that gets dismissed way too easily by the 'purest' IMHO.
 

John.Roo

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I like the term 'sponsored L/D'. 👍 It isn't limited only to electric and is an option that gets dismissed way too easily by the 'purest' IMHO.
Thanks ;)
It is true that L/D is not limited by electric propulsion, but electric propulsion is most suitable option:
- no need to "warm up" =power available immediately
- combustion engines would need special cooling system to keep optimal temp. range. It will run on a very low power settings
- easy to set requested power very precisely
- theoretically possible to "connect" with electronic flight instruments to allow options like "constant L/D" at any speed
- etc... it opens new possibilities for "open mind" (=not too conservative) pilots ;)

For example - "FES like" installation of propulsion system in nose is OK, however retractable propulsion systems are not optimal because pylon with motor (engine) makes additional drag.
 
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opcod

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It<s all about the market: if you do go the many glider club, mostly you see what : 1 - training and tourism flight in the morning and after a lineup of glider waiting for a sweet spot to fly for supposed good number. So having a glider for market not related to competition, with your own e-motor, give full freedom, but made to fly properly.. While a Sinus do quite good, better can be acheived. So minimum 50ft and +30:1
 

peter hudson

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Then there's the example of Sonja (MAP) and her motor glider CARO. she designed it, built it, flies it all over, and she doesn't know her L/D. So at least for that case it clearly isn't important. It doesn't affect the fun.

I think we all agree that for efficiency, SPAN rules. And most decisions about it for sailplanes are based on the max the rules allow for the category.
where it gets harder is when it's a personal design. Then the limits are: "how big is my shop?"; "where am I going to store it?" ; " how many pieces is reasonable for the wing to break into?". For these we can't possibly all agree on a span.

Also as span increases the spectre of flutter gets more pronounced, That adds risk to a design that is hard to quantify until the structural dynamics of the bird can be measured and a proper analysis done. Keeping the wings a little shorter and similar to something that works provides a lot of comfort and that is worth trading some performance for too!
 

Topaz

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Thanks ;)
It is true that L/D is not limited by electric propulsion, but electric propulsion is most suitable option:
- no need to "warm up" =power available immediately
- combustion engines would need special cooling system to keep optimal temp. range. It will run on a very low power settings)
- easy to set requested power very precisely
- theoretically possible to "connect" with electronic flight instruments to allow options like "constant L/D" at any speed
- etc... it opens new possibilities for "open mind" (=not too conservative) pilots ;)

For example - "FES like" installation of propulsion system in nose is OK, however retractable propulsion systems are not optimal because pylon with motor (engine) makes additional drag.
It's also an option for situations like my own, where you have a touring motorglider that compromises absolute drag reduction for more practicality in powered cruising mode. (Not everyone can own a Stemme 😉) Offsetting the extra cooling drag with a slight bit of thrust brings performance up to "pure glider" standards for a given span. I'm not flying competition, so it can't possibly be a matter of "cheating."

In my particular case, I know it's also going to be a while before I can obtain or (more likely) design and build a feathering prop for my plane. Since the engine is fixed on the nose, a fixed-pitch prop becomes an air brake unless I can get it stopped exactly across the cylinders. Even just letting the engine idle would be a huge improvement.

I'd love to go electric for propulsion, because all the options you describe are true, but I want a 300nm+ range under power. Batteries will catch up to that someday. 👍

EDIT: Something has been nagging at me in this conversation, and I finally put my finger on it. It's the notion that "setting and task and getting around" somehow takes a certain span or performance to be satisfying. No. And the way it was actually expressed was "setting a task on a day nobody else can even stay up, and getting around." The focus there is "...on a day nobody else can even stay up ...". There may not be a trophy involved, but that's competitiveness, that's competition. Again, if you're in competition, then fine, every bit of performance matters. 15m twenty years ago, 18m today, 23m twenty years from now. You need "an edge." Fine.

Not everyone flies competitively. Not everyone has to prove that they're better, faster, stronger, all the time. If that's your thing, fine. Have at it. I honestly don't care if someone stayed up longer than me, went farther than me. I fly for fun. And I can "set a task and get around" in any glider/motorglider there is, right down to an SGS 2-33. It won't be a 600km 0r 1,000km flight task in a lower-performance glider but, as I said, my late friend Gary got all his Diamonds in his SGS 1-26D. Now that's a challenge, and in a 12.2m ship!
 
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Victor Bravo

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Holy crap... Hot Wings, if you can find that snot-nosed a** h*** on RAS who had the gall to have that elitist attitude, tell him I would like to have a word with him out behind the hangar, and there will be a painful spanking involved:) I didn't know you went that far back in these ridiculous internet discussions... Were you there when that same guy realized that one of his boyhood heroes (and one of the great soaring pilots in history) was not as classy of a fellow as one had hoped?

mm4440 you are correct, wrap me in Depends and send me off to Happy Acres Alzheimer's Resort... now I remember that Greg Cole's Sparrowhawk was not really intended for microlift. It was to meet the 155 pound Part 103 regs with a "real" sailplane (I think Gary Osoba won the 15M nationals with four feet less span, embarrassing the crap out of the 15 meter span ships?).

For microlift I meant the LightHawk, which was an incredible techincal achievement (but a complete legal/financial boondoggle sponsored by the Law Firm of Ego, Arrogant, and Hubris).
 

WonderousMountain

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The Duckhawk won 15M ship W/O winglets and made podium in 18M class as 15M, there is also a 13.5 competition wingset, the SparrowHawk is 11M microlift capable.
 
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