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Nov 12, 2019, 12:23 PM
solastagia
kcaldwel's Avatar
Quote:
Originally Posted by Mr. Wiz
So in the wind we're suppose to fly nearly as fast (wind speed) down wind with our ballasted (faster) plane as we fly up wind. The ground speed at that point has to be pretty darn fast! So here is what goes thru my mind when flying in that condition. I damn well better know the lift is down there and reachable because I'm flying away from myself like a bat outta .... And, will I climb enough to make it home when I finally get there or will I be so far down wind that I can't see my plane?

Well, you can fly unballasted too slowly down wind, not reach the drifting thermal, and then not be able to get back against the wind. That's what I do!

Somehow it was easier to fly MacCready speeds from 15,000' on a glide to the next cloud, than with a DLG from my pitiful launch height.

Kevin
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Nov 12, 2019, 02:57 PM
Come out swinging
sporter's Avatar
You better have a REALLY good reason to track way downwind (past the point of no return) chasing a thermal. You better have a solid read or there are other gliders in clear strong lift. In my mind this is amplified when ballasted. The glider is flying really fast, which means your decision time is reduced. Personally, if I had a clear read for strong lift, I probably wouldn't ballast. This is because I expect to get up high enough to get home without ballast. I am more interested in getting as high as fast as possible. I also think the only time I would ballast is if I can't get the plane to fly forward.

Sean
Nov 12, 2019, 03:14 PM
Dark Side of the Red Merle
Curtis Suter's Avatar
One of my favorite website tutorials that goes with what other's have shown here, it's from a full scale designated glider examiner.

http://www.5c1.net/Glider%20Performance%20Airspeeds.htm

Curtis
Nov 12, 2019, 04:59 PM
Time for me to Fly...
Mr. Wiz's Avatar
Quote:
Originally Posted by Curtis Suter
One of my favorite website tutorials that goes with what other's have shown here, it's from a full scale designated glider examiner.

http://www.5c1.net/Glider%20Performance%20Airspeeds.htm

Curtis
That’s the third link to that info in this thread.... I’ve seen it before too. It helps kinda explain what’s happening with our DLG’s but I didn’t see anything there that I could actually put into practice... other than to fly faster when ballasted, in the wind.

Maybe the secret is to fly with ballast in dead calm and make some observations (with a watch) about how it effected the plane and then ballast accordingly when the wind is up.
Latest blog entry: Something old is new again
Nov 13, 2019, 09:59 AM
Barney Fife, Vigilante
tom43004's Avatar
Mike, try going out on a normal day when there is some really active air and adding ballast when you normally wouldn't. See how it changes your flying. Now add DOUBLE that ballast and fly again. See how it changes your flying.

Many people don't fly well with ballast because they simply stop flying when the wind / turbulence levels exceed their comfort zone. They're inexperienced in carrying weight. What you will find is that the more you fly with weight, the less anxiety you have about it, and the more you'll do it. Also, after you get comfortable carrying weight, you'll probably notice changes to your decision making. When you're carrying, you typically have to be a little more decisive than when you're not... at least that's what you may feel. In reality, after getting comfortable carrying, and having your flying style more suited to it, you may find that your options are more limited when you're NOT carrying.

Dead calm is a different beast. That's about the only time I don't carry.
Nov 13, 2019, 12:06 PM
In F3J size does matter!
roydor's Avatar
When I’m practicing and there is a certain amount of wind that “requires” a certain amount of ballast I fly a few flights with the amount of ballast I think is needed (what I would normally choose if I were in a competition) then I fly a few flights with 20-40 grams over that amount and 20-40 grams less then that amount.
This approach allows me to see how ballast affects the way the model fly’s and also to practice “incorrect” ballast choice as sometimes you find yourself too light or too heavy due to misjudgment or a rapid change in the conditions.

One thing I noticed over the years is that my ballast choice has “evolved” over the years and today I prefer to fly heavier then I used to in the past, mainly because of the possibilities ballast opens up and also because I recognize today that 20 grams difference does not make a model “too light” or “too heavy”, if you think you can’t come back or make your time due to 20 grams, you are just looking for excuses...

Roy
Nov 13, 2019, 12:40 PM
Time for me to Fly...
Mr. Wiz's Avatar
Lol.... that’s a funny last comment, Roy.

I’ll definitely be giving things a try based on this discussion. Thank you to all that responded with advice.
Latest blog entry: Something old is new again
Nov 16, 2019, 11:33 AM
FIN-5414
meeks's Avatar

m/s


Now,
this thread is a great read, being the worst wind flyer in the world (proven in Hungary) In particular I like the theoretical parts of the discussion and can extract quite a bit of new information for the next (windy) season.

However, one small but crucial detail still evades me even after many years of flying DLGs: how to best determine the vertical and horizontal plane speed (m/s). Having access to both altitude and GPS data during or post flying session is obviously one way but back in the days when these were a distant dream how did you figure those parameters out?

Looking forward to the secret formula which helps me to prevent the land outs next summer!

Cheerio,

>m
Last edited by meeks; Nov 16, 2019 at 11:59 AM.
Nov 16, 2019, 11:47 AM
Registered User
Quote:
Originally Posted by Rich Erikson
Hello.... i am brand new to DLG gliders (well any glider for that matter)and have a vague understanding about ballast.... but I am hoping this thread can be used to explain ballast in-depth... just not by me ;-)
Can you guys chime in on the why it is done... how to decide how much to use... changes in cg... I want to know it all... and I know virtually nothing now.

I tried to search... but ballast is a common term and appears in a million threads.

its help a nooby day!
Glad you asked, this thread now has some great info. Time to study those graphs!

On the practical side, if your field has any boundaries or tree lines you'd rather not land outside of, just ballast up and enjoy the wind. Many many times I wish I put more ballast in and almost none where I wish I had less ballast. Same for contests.
Nov 18, 2019, 01:12 PM
hot air rises...
jfinch's Avatar
Quote:
Originally Posted by meeks
Now,
this thread is a great read, being the worst wind flyer in the world (proven in Hungary) In particular I like the theoretical parts of the discussion and can extract quite a bit of new information for the next (windy) season.

However, one small but crucial detail still evades me even after many years of flying DLGs: how to best determine the vertical and horizontal plane speed (m/s). Having access to both altitude and GPS data during or post flying session is obviously one way but back in the days when these were a distant dream how did you figure those parameters out?

Looking forward to the secret formula which helps me to prevent the land outs next summer!

Cheerio,

>m
This is how I do it.
For minimum sink: Get up in the morning before the sun comes up, just barely light enough to see your plane at distance on a day without any wind. Pick a camber setting, launch and trim for the slowest speed you can control. Relaunch and fly with minimal stick inputs (big circle or straight out and back). Time the flight. Do this 5 times. Now change elevator trim setting so the plane flys a little faster. Repeat. Trim faster again, repeat. repeat. You'll find the correct flying speed for that camber by the longest flight times. Be honest with yourself and if you start to notice any lift or even neutral air stop testing and come back on a different morning. You can then do this all again for a different camber setting. Obviously an altimeter is helpful here as you can plot the data and pick the best slope.

For cruise (best L/D): I think this is pretty subjective... I will do a quick 5' dive in minimum sink mode and note how quickly the plane recovers (it's usually pretty quick on my planes). Then go to the manufacturers suggested camber setting for cruise mode (usually level/even with the fixed sections of the wings trailing edge) and trim for a recovery from the same kinda dive in 2x-3x as much time. I'm not sure this the correct way to do it, but thats how I do it.

For speed/launch: Trim for straight flight regardless of airspeed at the manufacturers recommended reflex setting. That's it if you don't have an altimeter. If you do have an altimeter then launch a bunch in the morning at different reflex setting and pick the one that launches the highest.
Nov 18, 2019, 07:25 PM
Registered User
I have found this link useful - http://www.5c1.net/Glider%20Performance%20Airspeeds.htm
Nov 20, 2019, 02:15 AM
FIN-5414
meeks's Avatar
Jon,
thanks for the approach, it sounds perfectly reasonable and doable to me (except of the part getting up on the field before the first pigs fart). I’ll combine this approach with a GPS-logger and altimeter. Pretty curious what comes out....

Cheers,
Nov 20, 2019, 09:50 AM
Wayne Wimbish
wdwimbish's Avatar
Quote:
Originally Posted by Marin Mitev
That is a really good link. I bookmarked it so that I could really digest it later.

Thanks,
Wayne
Latest blog entry: Paying for Purchases by PayPal
Nov 20, 2019, 12:22 PM
Oleg Golovidov
olgol's Avatar
And it has been only posted 3 times in this thread...
Nov 20, 2019, 05:03 PM
hot air rises...
jfinch's Avatar
I like this link: http://www.5c1.net/Glider%20Performance%20Airspeeds.htm


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