Why 1.5 meters? - Page 3 - RC Groups
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Jan 03, 2018, 06:40 AM
Team Spektrum FPV
aaronredbaron's Avatar
I would love a bigger DLG I could really put some weight into. I've only had some 1st gen DLGs about 16 years ago, and recently a dlg foamy (hand-me down, why not?), but I'm 6'6" and I've got 275 pounds of mass to put into it, and I've always wondered if I could get more out of a bigger DLG.
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Jan 03, 2018, 06:52 AM
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I hope others have noticed this but the answer to the original question seems to be pretty obvious at this point. DLG's are 1.5m because that is the size being flown in competition, the answer really is that simple. Pretty much every answer supporting the idea that 1.5M is the ideal size was using competition flying to support their premise.

Thomas mentioned flying his 1m in some events and doing well. Beyond that I think one of the reasons he flew the 1M is that they are fun to fly ! I could be wrong but I would bet that was part of the equation.

I also wonder how many of those who are commenting have spent any amount of time flying DLG's with different wing spans? I have spent quite a bit of time flying DLG's of all sizes. For me I simply don't enjoy flying 1.5m DLG's. I actually love 1.3m planes, it seems to be a nice balance between 1m and 1.5m.

I wonder what size would be people's favorite size to fly if the rules had not dictated 1.5m or if they were not looking at this purely from a competition standpoint.

So, removing the competition stuff all together what size DLG would most of you enjoy flying?
Jan 03, 2018, 06:54 AM
Closed Account
Quote:
Originally Posted by aaronredbaron
I would love a bigger DLG I could really put some weight into. I've only had some 1st gen DLGs about 16 years ago, and recently a dlg foamy (hand-me down, why not?), but I'm 6'6" and I've got 275 pounds of mass to put into it, and I've always wondered if I could get more out of a bigger DLG.
I may be able to help you with that..... I have been kicking around the idea of doing a 2m DLG just for the fun of building one. I already have a 2M hi start wing it would not take much to do a DLG wing.
Jan 03, 2018, 06:55 AM
Closed Account
Quote:
Originally Posted by ThomasLee
I'm 5'7
Like I said 5'8" on a good day, otherwise I am right there with you.....
Jan 03, 2018, 07:33 AM
ThomasLee's Avatar
1m and 1.5m are both fun for me... I mainly chose to bring the 1m on the US and Japan trip because it's easy to travel with, and I didn't have a 2p model at the time. I flew it in our league contests because I wanted to see how it flew against 1.5 m models. I just wanted to point out that flying a 1m in an F3K contest is okay. You probably won't get in the flyoffs with one, but you'll still have fun.
Jan 03, 2018, 09:18 AM
Transplant Chey WY from Reno
Thermaln2's Avatar
Quote:
Originally Posted by krikkens
Have you seen or tried it? i've seen both 2m and 2.5m dlg thrown by f3k pilots and the way you rotate to throw it is totally diffrent , especially the 2.5meter glider launched very low , somewhere around 20meter i think it was , while the same guy launches a 1.5m dlg to 70m+
Krikkens,

Your questions actually prove my point. If the span was open, i. e. unrestricted, then each pilot would probably find the optimum dimensions for their flying style, body, ability and such. My first HLG, for Thornburgs contest, was 66" because that was what I found my arm could throw, and the wing area and airfoil was adjusted to what I needed for myself. Nearly everyone else was just flying their main TD ship.

If you have a greater span you will see an improvement in duration, and perhaps that would be not due to how high you can throw it, but what the sink rate is for the height you could/can get. What would end might be the offerings of manufacturers because now one glider, or glider type, does not necessarily match what the general public needs or desires. So if you are a designer/competitor then this is to your advantage, and if you are a MFDer, then you see a company disadvantage.

Personally, I am on the designer side and hence I will take the initiative to build a plane that fits my capabilities. There was an old HLG freeflight champ who knew his planes were better, and he knew no matter what air he threw in when you threw, his plane would get a longer flight. It is the same in our DLG circles (no pun intended), if I can't throw as high, but I can out-sink your plane and still get to the thermals just like the "gorilla's" then low and behold I all of a sudden become competitive.

It's all on how you look at it.

Chris
Jan 03, 2018, 09:22 AM
Transplant Chey WY from Reno
Thermaln2's Avatar
Quote:
Originally Posted by The_Builder
I hope others have noticed this but the answer to the original question seems to be pretty obvious at this point. DLG's are 1.5m because that is the size being flown in competition, the answer really is that simple. Pretty much every answer supporting the idea that 1.5M is the ideal size was using competition flying to support their premise.

Thomas mentioned flying his 1m in some events and doing well. Beyond that I think one of the reasons he flew the 1M is that they are fun to fly ! I could be wrong but I would bet that was part of the equation.

I also wonder how many of those who are commenting have spent any amount of time flying DLG's with different wing spans? I have spent quite a bit of time flying DLG's of all sizes. For me I simply don't enjoy flying 1.5m DLG's. I actually love 1.3m planes, it seems to be a nice balance between 1m and 1.5m.

I wonder what size would be people's favorite size to fly if the rules had not dictated 1.5m or if they were not looking at this purely from a competition standpoint.

So, removing the competition stuff all together what size DLG would most of you enjoy flying?
Paul,

Yes I agree with you . It is the design limitation for the class, the upper limit. If 1.3M ships got 30 ft higher than 1.5 M ships, and still had the same general sink rates, ranging, etc, then the 1.5M dimension would not be the limiting factor. But in our case it is. After that it comes down to what you like to fly, how you fly (technique) and then ease of getting and keeping a plane in tip top shape.

Chris
Jan 03, 2018, 09:28 AM
Transplant Chey WY from Reno
Thermaln2's Avatar
I'd like to add another note. Many of our designs are limited by many other factors that we often don't acknowledge as issues. For example, radio weight, while going down, it still remains. Likewise we have servso thickness because everyone wants to put the servos in the wings. Then there is the flaperons controls and methods, and in conjuction to that having 4 in the pod. And probably above all, our short sightedness to not deviate too much from the norm. (my opinion).

As such, I , like any good individual designer, have thought of trends that might change designs a lot more. But as with any idea, you have to get them tried, and that is what I try to address in the shop.

Chris
Jan 03, 2018, 09:31 AM
In F3J size does matter!
roydor's Avatar
I remembered seeing clips of the Gigantalus, a stretched Tantalus, by Vincent merlin. A quick look on YouTube ant found these:
gigantalus starts (1 min 30 sec)


gigantalus, fun in low level thermals (1 min 25 sec)


Vincent Merlijns - "dolle Show, dolle Show" mit Miss Gigantalus (F3K, DLG, SAL, HLG) (0 min 33 sec)


IMG 0483 (1 min 16 sec)
Jan 03, 2018, 09:42 AM
1 revolution and throw!
Quote:
Originally Posted by roydor
I remembered seeing clips of the Gigantalus, a stretched Tantalus, by Vincent merlin. A quick look on YouTube ant found these:
https://youtu.be/_UpNQCq7ZSw

https://youtu.be/_7cJyVpB1n8

https://youtu.be/5Ocd0bdiYpU

https://youtu.be/0vnjVoT54H0
that was the 2.5meter plane i was refering too , this guy throws his dlg to 70m+ but if i'm correct he was only getting around 20m out of this one .
Jan 03, 2018, 09:42 AM
hot air rises...
jfinch's Avatar
Probably the wrong group to ask in, but what is a "typical" early morning sink rate for a 3m glider?
Jan 03, 2018, 10:08 AM
In F3J size does matter!
roydor's Avatar
Quote:
Originally Posted by jfinch
Probably the wrong group to ask in, but what is a "typical" early morning sink rate for a 3m glider?
Can’t say about the 3 meter gliders because I don’t fly them but I do fly 4 meter F5J and the light ones can reach about 0.25 m/s sink rate. 1.5 m F3K’s reach about 0.27m/s so the difference isn’t great. The main difference between the smaller span F3K and bigger F5J is the L/D and it can be as much as 30% better. So using a bigger span DLG that launches lower you probably won’t out float a 1.5 m DLG in dead air but you will be able to reach further out if there is air and come back. That is as long as you’re not launching 30% lower because then the 1.5 m DLG will out glide you due to the higher start and out float you, again due to the higher start.

This is why I think the differences won’t be night and day, you’ll be trading height for some float or float for some height due to your personal preference, similar to what we have today on the market today, some have high launching models with slightly reduced float, some have floatier models with reduced launch.
Last edited by roydor; Jan 03, 2018 at 10:13 AM.
Jan 03, 2018, 10:29 AM
1 revolution and throw!
Quote:
Originally Posted by roydor
Can’t say about the 3 meter gliders because I don’t fly them but I do fly 4 meter F5J and the light ones can reach about 0.25 m/s sink rate. 1.5 m F3K’s reach about 0.27m/s so the difference isn’t great. The main difference between the smaller span F3K and bigger F5J is the L/D and it can be as much as 30% better. So using a bigger span DLG that launches lower you probably won’t out float a 1.5 m DLG in dead air but you will be able to reach further out if there is air and come back. That is as long as you’re not launching 30% lower because then the 1.5 m DLG will out glide you due to the higher start and out float you, again due to the higher start.

This is why I think the differences won’t be night and day, you’ll be trading height for some float or float for some height due to your personal preference, similar to what we have today on the market today, some have high launching models with slightly reduced float, some have floatier models with reduced launch.
in f3k planes are all about high launching these days , nobody will buy a 185-190mm root dlg anymore i think .
that's also the reason i think more span will garantue lower averag contest results , people know what launchheight means .
launching higher can get you jst above the turblent air coming over trees , can get you just in that next layer of air on an open field that is better then what's below , gives you more room and time to try something ,etc....
in good air turnaround time will suffer so i expect more span is always a disadvantage , and i mean going to 2 meter orso , adding a few cm could work for some offcourse....

you cannot underestimate the importance of launchheight , in belgium i always had an advantage in launchheight (nowadys rather small , some others are catching up very well) but in the past the 20% higher launches over some others brought me 40% orso more flight time , just that other layer of air or the possibilty to reach out where other couldn't go made this diffrence .

offcourse our average weather is windy and offenly nasty , windy up to the point we are jamming the fuse full of ballast and max make 2 or 3 turns in 1 flight because 1 turn means 30 meter downwind and groundspeed witot putting it into a dive is near zero even with this ballast
offtenly the sink rate increases when comming closer the the ground
Last edited by krikkens; Jan 03, 2018 at 10:35 AM.
Jan 03, 2018, 11:12 AM
Oleg Golovidov
olgol's Avatar
Quote:
Originally Posted by krikkens
in good air turnaround time will suffer so i expect more span is always a disadvantage , and i mean going to 2 meter orso , adding a few cm could work for some offcourse....

offcourse our average weather is windy and offenly nasty , windy up to the point we are jamming the fuse full of ballast and max make 2 or 3 turns in 1 flight because 1 turn means 30 meter downwind and groundspeed witot putting it into a dive is near zero even with this ballast
offtenly the sink rate increases when comming closer the the ground
Kristof, maybe a larger span would allow you to make 5-6 turns (instead of 1-2 turns) in your windy conditions and still penetrate back to the field.

I for one am very curious to see what an unlimited HL class would evolve into
Even now, with the same launch techniques, for an average pilot, I think a slightly larger span would not reduce the launch height, and improve the glide. So 1.6m or even 1.7m could easily become the preferred span. With a double spin technique, we can probably launch 1.8-2.0m models to nearly the same height as we launch 1.5m models.
Just fun to think about it. It would be a very interesting design optimization challenge.
Jan 03, 2018, 11:21 AM
Closed Account
Quote:
Originally Posted by krikkens
in f3k planes are all about high launching these days , nobody will buy a 185-190mm root dlg anymore i think .


you cannot underestimate the importance of launchheight , in belgium i always had an advantage in launchheight (nowadys rather small , some others are catching up very well) but in the past the 20% higher launches over some others brought me 40% orso more flight time , just that other layer of air or the possibilty to reach out where other couldn't go made this diffrence .

These are some great comments and reinforce some thoughts I have had for some time.


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