New glider design

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watt

Member
Joined
Sep 8, 2014
Messages
16
Location
France
Hello everyone,
I have been designing aircraft for eight years now, and my last post here was in 2014 for a four seat long range aircraft.
Being also a glider pilot I have decided to turn my attention to them.
Glider design seems pretty straightforward as everyone pretty much copies the same concept from 1978 working hard to find small defect to correct, airfoils and materials to improve and every time the performances improves by a couple of L/D points a new glider is born.
Being interested mostly by the design process I have decided to try something new and start with the motivations of glider pilots. I am hoping to have an Ah-ah! moment that will explain better why we fly.
I have put together this small 5mn study that will help me understand "Where" to start with my design. It is as much a performance wish list as it is a psychological study on the brain of pilots.
I am an amateur, this is non commercial and I will share my findings on this thread when done.
Cheers

Soaring study
 

blane.c

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HBA Supporter
Joined
Jun 27, 2015
Messages
5,027
Location
capital district NY
Hello everyone,
I have been designing aircraft for eight years now, and my last post here was in 2014 for a four seat long range aircraft.
Being also a glider pilot I have decided to turn my attention to them.
Glider design seems pretty straightforward as everyone pretty much copies the same concept from 1978 working hard to find small defect to correct, airfoils and materials to improve and every time the performances improves by a couple of L/D points a new glider is born.
Being interested mostly by the design process I have decided to try something new and start with the motivations of glider pilots. I am hoping to have an Ah-ah! moment that will explain better why we fly.
I have put together this small 5mn study that will help me understand "Where" to start with my design. It is as much a performance wish list as it is a psychological study on the brain of pilots.
I am an amateur, this is non commercial and I will share my findings on this thread when done.
Cheers

Soaring study
I am interested in a touring glider. I have no glider experience so your Soaring study isn't applicable to me.
 

mm4440

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Joined
Jan 14, 2012
Messages
288
Location
LA area, CA
I am interested in a touring glider. I have no glider experience so your Soaring study isn't applicable to me.
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.
 

watt

Member
Joined
Sep 8, 2014
Messages
16
Location
France
I am interested in a touring glider. I have no glider experience so your Soaring study isn't applicable to me.
I don't know what a touring glider is, but it is a start in an interesting direction (btw I know what a touring motor glider is.)
 

Victor Bravo

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Joined
Jul 30, 2014
Messages
9,704
Location
KWHP, Los Angeles CA, USA
The SCUD in Post #6 is an exceptional achievement.

They managed to take the very simplest model airplane style "box fuselage" that you could build... and find a way to make it more complicated to build, with no increase in parts count.
 

Exian

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Joined
Jul 26, 2018
Messages
54
Location
BORDEAUX
Please keep us updated with your progress/ideas on this project.

By the way, I am already working on the glider that suits my answers in your study...
 

User27

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Joined
Apr 5, 2015
Messages
123
Location
England
I think your study is a little limited, why have you missed out 18m gliders? On the assumption that you will not be designing a World Championship winning glider (otherwise you would be working for Schempp-Hirth, Schleicher or Jonker) why would you concentrate on the existing classes? The only time these classes are relevant are at the Worlds/Continental/National Championships. If a pilot is not interested in winning a championship - I'm guessing 95% of pilots are not - then the classes are not relevant. Witness the popularity of 18m unflapped gliders and 21m flapped. These are great gliders for club pilots, and still competitive in handicap competitions. 13.5m gliders seem to be largely a waste of time. Compare a new 13.5m aircraft to an older, longer span, glider for a similar price. Much more performance is available with little downside.

From my (perhaps peculiar) perspective a good condition 18m 2nd hand glider, with a turbo, is the best value in today's market. Open class gliders are too difficult to handle on the ground (too big and heavy), although they are relatively inexpensive 2nd hand. Standard class (or 13.5m) is too small to carry an engine (gas or electric) in weak conditions. So 18m or so (flapped or unflapped) is the way to go. If you are designing from scratch for a recreational pilot I would say cockpit comfort is high on the list, as is ease of rigging & ground handling. Good in-flight handling is more important than ultimate performance. I use water most times I fly, so would say the ability to vary wing loading is important. To put it another way the ability to achieve a light wing loading in weak conditions is useful (so design in sufficient wing area), and the ability to increase the wing loading in strong conditions also increases the pilot's enjoyment of his flying.

Hope this helps ...
 

Jimstix

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Joined
Sep 29, 2012
Messages
160
Location
LAS CRUCES NM
A few thoughts: Write down your glider requirements - features or performance that you must have. Don't forget things like ease of assembly, will it fit on a trailer, pilot parachute or BRS? You will be sitting in the glider for hours at a time (getting that Diamond badge) so it needs to be comfortable for your butt, back, legs, shoulders, and head.
Most gliders are 15m standard class machines, so here are some data from older 15m ships..

1631373754183.png
So, I would start with the average numbers for wing area, AR, empty weight, max takeoff weight and work from there. Maybe, using modern materials, airfoils, and fabrication techniques, you can do better. Keep us posted. Jim
 

Bille Floyd

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Joined
Sep 26, 2019
Messages
517
...
To put it another way the ability to achieve a light wing loading in weak conditions is useful (so design in sufficient wing area), and the ability to increase the wing loading in strong conditions also increases the pilot's enjoyment of his flying.

Hope this helps ...
100% agree , with your assessment !!

The first time I pulled the handle, to deploy a Fowler-Flap, on
an L-13 , (in 1998) and felt the initial drag, push my body forward in
the cockpit ; that is when I first realised what the ability of creating
different wing-loading, and CL , on a glider , (Could) lead to, if taken to
an extreme.

Fast forward ; about a decade :
I was flying a glider called the Exxtacy, alongside a friend on
a Ghostbuster , that had a retractable flap ; when he retracted
his flap, (he left me in the dirt) as he pulled away !! :(
That is when i Really Wanted, a retractable flap
that could + or - a much larger wing aria, to affect wing-loading
a Lot more .

I made a Thread on the subject a while back ; wanted
to learn more about , how it works :

Bille
 

Topaz

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Orange County, California
I think your study is a little limited, why have you missed out 18m gliders? ...
I can remember the days when people were saying "if you're not flying 15m, you're just not serious." Now it's 18m.

At the 2019 ESA Western Workshop, one of the presenters casually polled the room about what the attendees felt would be an "adequate" sailplane/motorglider for casual/fun-flying use. In other words, not competition-oriented. The attendees in question ranged from neophytes to some of the absolute legends of ultralight and light soaring, to high-performance sailplane manufacturers, to NASA aerodynamics researchers (several of the latter).

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.
 

opcod

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Aug 28, 2010
Messages
97
Location
Canada
A pipistrel sinus is also a motorglider with 26:1 , and same as a cf-18 is also a glider at 1:35 . If the market is for ulm to compete agains Silent .. ok, But for the rest, no interest under a 50ft wingspan. And wingextension are the key. Steeme have retact one if the taxi is a concern .. But as being a pure glider... if it,s uber cheap into the ulm cat.. perhaps, but wing that short is just a skip.
 

TFF

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Joined
Apr 28, 2010
Messages
15,602
Location
Memphis, TN
I only read the questions, not being a glider pilot I did not answer, but I don’t think the questions were concrete in designing a new sailplane.

The factions seem to be well drawn out. Competition is easy. Best wins. If someone wants that trophy in whatever class, they spend what it takes. Everyone else is harder to design for.

Nature abhors a vacuum. If you don’t see a vacuum in some direction, whatever is designed has to create one. Be so good, that everyone has to have it. Performance, looks, cost. What you design has to be an expert in at lest one but probably two. Hard hurting want is the only way.

Personally I would want a 1-26 like kit. Not chasing trophies, but it would be nice to have either plans or let’s say a $10k kit with everything to build a sport glider. One not too dainty for the Everyman. Graduation to something else would be fine down the road or just plug away with what you got and have fun. Something that can be passed down over time, because it’s value is not in being able to fly another ten seconds longer over competitor, or it’s obsolete.

The HP-24 is going to be hard to beat, unless you can do it a lot cheaper, or it has to be 13.5m.
 

Erik Snyman

Well-Known Member
Joined
Oct 9, 2019
Messages
99
Hello everyone,
I have been designing aircraft for eight years now, and my last post here was in 2014 for a four seat long range aircraft.
Being also a glider pilot I have decided to turn my attention to them.
Glider design seems pretty straightforward as everyone pretty much copies the same concept from 1978 working hard to find small defect to correct, airfoils and materials to improve and every time the performances improves by a couple of L/D points a new glider is born.
Being interested mostly by the design process I have decided to try something new and start with the motivations of glider pilots. I am hoping to have an Ah-ah! moment that will explain better why we fly.
I have put together this small 5mn study that will help me understand "Where" to start with my design. It is as much a performance wish list as it is a psychological study on the brain of pilots.
I am an amateur, this is non commercial and I will share my findings on this thread when done.
Cheers

Soaring study
Not a glider pilot, but please put up a link to your 2014 long distance four seat plane design.
Erik in Oz
 
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