SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Nov 30, 2011, 11:30 PM
a.k.a. Bob Parks
Glendale, AZ
Joined Jun 2008
2,382 Posts
I have a how high and a Ram3 in my dlg, and often see a big difference between the two altimeters. It is not a consistent amount during a typical flight session.

BP
bbbp is offline Find More Posts by bbbp
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 30, 2011, 11:38 PM
Kyle Clayton
Wave Glider's Avatar
United States, VA, Dinwiddie
Joined Feb 2008
2,438 Posts
I see. It would interesting to test that idea and see if it really would work as hypothesized. Well I can't argue with you about his work!
Wave Glider is online now Find More Posts by Wave Glider
RCG Plus Member
Latest blog entry: Helios and XXLite DLG
Reply With Quote
Old Dec 01, 2011, 12:59 AM
Full disclosure, not sponsored
JONBOYLEMON's Avatar
United States, UT, American Fork
Joined May 2002
17,127 Posts
Not to thread drift, but I did the dead air test with my B3 and flaps. I got past a certain point, something like 4 mm, and the flight times started going down. I did not however do a big time flap like I use on landings.... Is that what you are saying?

If so, its back to the field for more dead air testing.
JONBOYLEMON is offline Find More Posts by JONBOYLEMON
Reply With Quote
Old Dec 01, 2011, 01:22 AM
Registered User
Woodinville, WA
Joined Jul 2009
442 Posts
This is torture! 67 meters but not sure about the altimeter's accuracy!

If 200'+ launches become the norm, would tasks be in need of modifying?

Joseph
JoeCube is offline Find More Posts by JoeCube
Reply With Quote
Old Dec 01, 2011, 01:25 AM
G_T
Registered User
Joined Apr 2009
5,884 Posts
Chris,

It is routine for many to use 4 degrees of camber relative to speed mode for float mode and sometimes even more. 3.5mm for Edge is about the least of the set when it comes to min sink settings for calm air. The setting is of course dependent on the wing design which includes the airfoil family.

The confusion might come from some mouldies having their wings made in cruise camber rather than speed camber. Such wings already have 1.5 to 2.5 degrees of flaperon camber built-in, relative to speed mode. So a couple additional degrees gives a starting float setting.

Gerald

PS - 30 degrees of typical mild DLG landing approach flaps gives about 15% total camber. I'm not sure where the 3.8% came from relative to landing flaps... If you mean sufficient flaperon deflection to get the total percentage camber to 3.8% then that is somewhere in the neighborhood of 7 degrees down from speed mode. The required airspeed tolerance for good performance is tight at that point. If one can fly a DLG precisely enough and the air is calm enough and the wing design supports it then perhaps 7 degrees would be better than 4 degrees down. Rarely, IMO.
G_T is offline Find More Posts by G_T
Last edited by G_T; Dec 01, 2011 at 01:47 AM.
Reply With Quote
Old Dec 01, 2011, 03:20 AM
Registered User
Joined Aug 2009
1,278 Posts
hi,

first of all the 67 meter ,it was windy outside (average of 63-64 that day)

the day before ,no or very little wind, i got 55meter average (56max it was i believe)

meassured with my own ram3 , the z-log showed higher results on the first day(didn't had it on the second,windy day)

as for camber , i immediatly noticed it could handle more camber then what i was used to, when ballasted a lot more then empty .

empty i had about 6 of camber and ballasted i went to 8 or a bit more and still didn't had the feeling i wen't over the top.

also my 45gram ballasted didn't seemed to suffer performance , next time the weather permits flying , i will trim off the horizontal tip's
and also fly with more ballast , probably even more cambered.

-kristof-
krikkens is online now Find More Posts by krikkens
Reply With Quote
Old Dec 01, 2011, 08:40 AM
Registered User
United States, FL, Gainesville
Joined Nov 2004
232 Posts
Not sure this is completely relevant to the discussion, but thought I would share my experience with an old beat-up Twister I I fly. Had to rebuild it with a new fuse after a power-off launch (don't ask!) and used an early Tom fuse design which was much heavier than the original Twister fuse. Along with the repairs and the new heavier fuse, the AUW went from 300 grams to over 330 g. As I flew the plane after the repairs it just seemed to come right down, very short flight times. I was using the recommended camber for thermal, but it just was no fun to fly. I hung it up for about 3 mos, then one day increased the camber to more than 10 degrees and she came alive! My dead-air flight times returned to my before-repair times, and she still climbs in lift as well! I was thrilled, and now fly her all the time with more than 10 degrees camber most of the time and she is a joy to fly. What a difference the added camber made with the increased weight! I would have never guessed that if I had not experienced it.

-Robin
rhoon is online now Find More Posts by rhoon
Reply With Quote
Old Dec 01, 2011, 10:32 AM
Kyle Clayton
Wave Glider's Avatar
United States, VA, Dinwiddie
Joined Feb 2008
2,438 Posts
What CG are you flying the XX at? Is it relative to the Helios (% of chord-wise, not direct measurment)? Is the location much more sensitive and the range smaller because of the very narrow chord?
Wave Glider is online now Find More Posts by Wave Glider
RCG Plus Member
Latest blog entry: Helios and XXLite DLG
Reply With Quote
Old Dec 01, 2011, 11:40 AM
Registered User
Joined Aug 2009
1,278 Posts
Quote:
Originally Posted by Wave Glider View Post
What CG are you flying the XX at? Is it relative to the Helios (% of chord-wise, not direct measurment)? Is the location much more sensitive and the range smaller because of the very narrow chord?
kyle,

haven't experimented with cg yet , started out around 60mm (just put it on my fingers and measured it )

i only wanted to know if it just might be good to start flying .

it felt really well like that on the windless day , i made a piece of ballast bringing the cg more upfront (by 2or3?mm i guess) that too feld just about right .

i like my cg far upfront , but i will test some more locations when the weather gets better (we're close to storm for a few day's)

-kristof-
krikkens is online now Find More Posts by krikkens
Reply With Quote
Old Dec 01, 2011, 11:51 AM
Jens Hoffmann
jensdk's Avatar
Denmark, Region Zealand, Herlufmagle
Joined Jul 2006
437 Posts
Quote:
Originally Posted by JoeCube View Post
This is torture! 67 meters but not sure about the altimeter's accuracy!

If 200'+ launches become the norm, would tasks be in need of modifying?

Joseph
they are !!
jensdk is offline Find More Posts by jensdk
Reply With Quote
Old Dec 01, 2011, 11:59 AM
Jens Hoffmann
jensdk's Avatar
Denmark, Region Zealand, Herlufmagle
Joined Jul 2006
437 Posts
Quote:
Originally Posted by rhoon View Post
Not sure this is completely relevant to the discussion, but thought I would share my experience with an old beat-up Twister I I fly. Had to rebuild it with a new fuse after a power-off launch (don't ask!) and used an early Tom fuse design which was much heavier than the original Twister fuse. Along with the repairs and the new heavier fuse, the AUW went from 300 grams to over 330 g. As I flew the plane after the repairs it just seemed to come right down, very short flight times. I was using the recommended camber for thermal, but it just was no fun to fly. I hung it up for about 3 mos, then one day increased the camber to more than 10 degrees and she came alive! My dead-air flight times returned to my before-repair times, and she still climbs in lift as well! I was thrilled, and now fly her all the time with more than 10 degrees camber most of the time and she is a joy to fly. What a difference the added camber made with the increased weight! I would have never guessed that if I had not experienced it.

-Robin
What a great example, of the philosophy that's involved in flying.
And another reason to spend a lot of time experimenting with setting to finetune.
Use the forum as a guideline, then finetune by yourself.
There ain't no easy way to the top and one cannot buy skill

I love it !!
jensdk is offline Find More Posts by jensdk
Reply With Quote
Old Dec 01, 2011, 12:30 PM
Registered User
ydevriendt's Avatar
COSMOPOLITAN
Joined Oct 2005
522 Posts
Quote:
Originally Posted by Thermaln2 View Post
I am totally supporting Kristofs ideas, they are expectional.
I am very interested in Krstof's work, Grea t going, Kristof!
Chris,

You should sponsor him to set up a XXLite workshop in Reno. In his spare time he can go and lend a hand to Aerion who are just around the corner from you. They obviously need somebody to expedite the development of their supersonic corporate jet

Yves
ydevriendt is offline Find More Posts by ydevriendt
Reply With Quote
Old Dec 01, 2011, 04:32 PM
Registered User
United States, AZ, Arizona City
Joined Sep 2001
5,011 Posts
Chris,

What specific Drela F1 airfoil are you looking at? I wasn't even aware that he had developed any.

My FAI ff goes back so far, I can't relate to the current alphabet soup. Are you referring to a power airfoil? If so, I'd think those RE numbers are very comparable to hlg RE's. The last power ship I saw climbing (Eloy) was doing over 90 mph straight up, and the pilot was complaining about being down on RPM's.

Gary
GaryO is offline Find More Posts by GaryO
Reply With Quote
Old Dec 01, 2011, 05:27 PM
Registered User
Thermaln2's Avatar
Reno Nevada
Joined Oct 2007
2,647 Posts
Quote:
Originally Posted by GaryO View Post
Chris,

What specific Drela F1 airfoil are you looking at? I wasn't even aware that he had developed any.

My FAI ff goes back so far, I can't relate to the current alphabet soup. Are you referring to a power airfoil? If so, I'd think those RE numbers are very comparable to hlg RE's. The last power ship I saw climbing (Eloy) was doing over 90 mph straight up, and the pilot was complaining about being down on RPM's.

Gary
Gary,

The section I mentioned was the NG-01. I'd tell you which section in the DLG world I found this related to best (IMHO) but then I would get ripped apart for doing the comparisons as I have done for Zone comparsions. Ping me off line and I'll send you the coordinates. BTW, these wings are molded.

The airfoil is used on F1A towline gliders. For those who might be unfamiliar with the F1A glider and some of the things that are offered, take a look at these links, http://w-hobby.com/?p=Wings LDA and http://www.vasi.scana.com.ua/. I found this on You tube, which shows some of the launch techniques,
Freeflight F1A Towline Glider (0 min 54 sec)
, and then this one which was taken from the glider looking down,
F1A downward facing camera (2 min 13 sec)
,

I have read a few articles on the LDA F1H flights at Lost Hills (LDA = Low Drag Airfoils in their terms). The planes are like Kristof's, only bigger. We can discuss scaling versus performance effects, but let's not go there here.

The things I find of interest are really those that deal with lower sink rates and how they might be applicable to us. what I am seeing ar thicker sections, like 7% , which appears to be what happend when the Edge airfoils moved to the Zone airfoils, to improve AoA issues on simple glides. That is my opinion of course and I was glad to see them thicker since I mentioned it so much before the change. The links show some airfoils that are thicker and more undercambered, but you will see the parallels I am making.

Hope that helps.

Kristof,

Thanks for posting the increased camber trials. Very intersting. We might also be seeing an effect where the extra ballast is bringing the plane up to a flying speed that makes the airfoilswork better. It's nice that you are telling us about the real work results you see. Some designers I Know feel that you might need a minimum loading for some wings and airfoils, not just lighter.

Thanks,

Chris
Thermaln2 is offline Find More Posts by Thermaln2
Reply With Quote
Old Dec 02, 2011, 12:00 PM
Registered User
United States, SC, Mt Pleasant
Joined Nov 2003
1,206 Posts
To further derail the thread as we wait for more pics and flight reports...

Phil Pearson commented to me quite a few times that his Encore when loaded heavy (16 oz+) made use of added camber further then what Drela specified for the AG foils. The Encore also has a small section of true AG45 on the inboard section of the wing to increase lift of the wing. That wing is still one of the best out there, it just needs to be loaded so that it moves. Kind of like a Blaster.

On a related note, the Stobel instructions mention using deeper camber settings for the higher ballast weights. I have tested this a few times. When empty and using camber setting for highest ballast, the plane just mushes around the sky and flies too slow to really feel like it has positive control.

Chris,

I would be curious to see what you come up with. I have done a little research to see what the F1 guys are doing for inspiration although their tasks/goals are a bit different then ours. I have also researched soaring bird wing sections...now thats interesting.

James
hohensej is offline Find More Posts by hohensej
RCG Plus Member
Latest blog entry: Aerial Information
Reply With Quote
Reply


Thread Tools