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Jul 30, 2016, 05:03 PM
Wayne Wimbish
wdwimbish's Avatar
Both Streams came out at 240g at 77mm CG as most others in this thread use. At the Nats I had Oleg test them out and trim them for me.

He said that they were excessively neutral. Would not pull out at all in the dive test.

He had me add 4g to the nose to move CG forward. Now they will pull out very slightly in the dive test.

The surprising thing is that the CG now is at 72mm.

Should I worry about the forward number of the CG or just be glad now that the planes fly well and have a small amount of positive stability?

Advice?
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Jul 30, 2016, 05:48 PM
Time for me to Fly...
Mr. Wiz's Avatar
I always like my planes balanced near the forward end of the recommended CG range. I generally don't like the CG's people here say they use.
Jul 30, 2016, 11:49 PM
In F3J size does matter!
roydor's Avatar
That seems very strange... At 77 mm mine were pulling very well outbof the dive, about 3 seconds from a 30 degree dive to level.
I would suggest you ballast them to 260 grams and try trimming again, sometimes models fly differently when they are very light, sometimes we tend to try and fly them at a speed we are used to so push them faster. Check your elevator trim as well, is the elevator fairly symmetric or do you have a larga amount of trim? May also affect behaviour.
Jul 31, 2016, 12:28 PM
Oleg Golovidov
olgol's Avatar
Roy, was it in speed camber? or cruise? or thermal?
Wayne's model was very slightly stable, in speed camber (and trimmed for fast flight).
This is the most critical regime and most demanding of the forward CG.

Trim will not affect the behavior unless some weird airflow over the stab is happening that is very different from one speed to another. Elevator trim by itself is harmless and is not an indication of forward or aft CG necessarily.
Latest blog entry: DLG assembly service
Jul 31, 2016, 01:53 PM
In F3J size does matter!
roydor's Avatar
My test is always in cruise mode. In speed I intentionally trim the model not to pitch up so it tends to pick up speed and cruise at 150% cruise speed with a flat glide. In thermal it always pitches up more. I find the dive test as a test to get a "feel" for the model. The dive test is VERY trim dependant and cam be misleading but gives a "ball park" figure for the CG position.
Last edited by roydor; Jul 31, 2016 at 02:02 PM.
Jul 31, 2016, 03:56 PM
Wayne Wimbish
wdwimbish's Avatar
I have been flying both Streams this week at home. The red one is the one we added 4g nose weight to and is at 72mm. The red/green one is still 'as built' at 77mm cg.

The red one seems to be more stable in all flight modes and is pleasant to fly. The red/green one is quite twitchy by comparison and I have to keep an eye on it. It is a lot more pilot load.

I am planning to add some weight to the nose of the red/green one tonight to move the cg to 74/75mm and try it tomorrow morning to see how it feels.

At this point I am more interested in getting it flying comfortably for me rather than trying to hit a magic number.

Once I get to where I like it, then I will work to get both set up the same as much as possible.
Jul 31, 2016, 04:26 PM
In F3J size does matter!
roydor's Avatar
In the end the most important thing is to get the plane to fly well for YOU. There is no magic number and as long as you are comfortable, your number is as good as any.

Enjoy your Streams, still one of my favorite DLG's
Aug 01, 2016, 09:20 AM
Wayne Wimbish
wdwimbish's Avatar
Added ~2g to the red/green Stream moving the cg to 75mm. Trimmed Speed (0mm camber) for a very gentle pullout from the dive. Trimmed Cruise (2mm camber) and Thermal (4mm camber) to not porpoise.

Flew this morning at 7:30am in dead calm following early morning thunderstorms. Was very pleased with the performance.

I only launch to about 130-140' due to tendonosis in both ankles. I was consistently getting 1:40-1:45 min in cruise and a little more in thermal.

Then I started playing with the camber for float to see what effect it had. With 5mm camber times improved to over 1:55min. With 6mm camber times were over 2:00min. In fact I had 6 consecutive flights over 2:10 with the longest being 2:25. I have never had a plane that would do this before.

Oleg mentioned last week that he likes a crazy amount of camber. The question is, how much will it take, and under what conditions would you use it?
Last edited by wdwimbish; Aug 01, 2016 at 09:47 AM.
Aug 01, 2016, 10:30 AM
Oleg Golovidov
olgol's Avatar
I use crazy amounts of camber on NXT.
Stream classic probably does not need as much. But it is always good to find out how much is OK and how much is too much.
Latest blog entry: DLG assembly service
Aug 13, 2016, 06:42 PM
Ivan MacKenzie
imack's Avatar
After getting caught in big downpour at today's Canadian F3K Team Trials, my Stream wing is now covered in whitish "watermarks". Anybody know a good way to get rid of this?

Ivan MacKenzie.
Aug 13, 2016, 09:43 PM
Time for me to Fly...
Mr. Wiz's Avatar
Lemon Pledge
Aug 14, 2016, 04:18 AM
Ivan MacKenzie
imack's Avatar
Quote:
Originally Posted by Mr. Wiz
Lemon Pledge
Thanks Mike. Pledge was OK, but I had better results with Multisurface Windex.

Ivan MacKenzie.
Aug 22, 2016, 03:00 PM
RHX138
RHX138's Avatar
What CNC machine was used to make the molds? It looks like a HAAS..
Aug 22, 2016, 08:00 PM
Wayne Wimbish
wdwimbish's Avatar
Out flying again today about 7am. Dead calm about 30 min after sunrise. Heavy dew and some fog.

Have settled on 75mm for cg and really like the float with 6mm camber. I finally have a combo that will consistently beat my flying buddy's Tweagle in dead air from essentially equivalent launches.

Love it!
Aug 23, 2016, 03:43 AM
Registered User
Stream's Avatar
It was made with OKUMA


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