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Old Feb 03, 2006, 10:26 PM
It pays to be a winner
Keith R.'s Avatar
T-Town, AZ
Joined Jun 2004
1,733 Posts
Question
Dailing in the Mach Dart

Hey everyone. I have finally decided to get my mach dart really dialed in for this upcoming race @ parker. I think my CG is a little too far forward, and was curious what all you mach dart owners have your CG set at.

Also, what are your control throws, and how much camber and reflex to you use? And how much deflection do you have your ailerons have for snap flap, if you have it set up?

Thanks,
Keith
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Old Feb 04, 2006, 01:58 AM
more casual than stylish....
slopemeno's Avatar
Joined Jan 2003
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I'd love to hear the following, as I'm very close to the first flight.
CG: How far back?
Throws
Spoilerons and elevator compensation
Differential, if any

Also:
What thread is the little nylon bolt thats begging to break, and what SAE thread are you guys replacing it with? 4-40?
What thread are the v-tail bolts?
That should cover it I guess. Any news on the carbon version?
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Old Feb 04, 2006, 02:19 AM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
21,858 Posts
Slope-
I think the thread is 3mm or 4mm.
But I think I remember Bill L saying he tapped his out with either 6-32, or 8-32; I cant remember. Do a search on Mach Dart.

T
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Old Feb 04, 2006, 02:27 AM
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80SGliderDude's Avatar
W. Santa Cruz, CA
Joined Jun 2005
241 Posts
BillL's thread is here: http://www.rcgroups.com/forums/showthread.php?t=408301

I have a cg of 86 mm.

Flaperon mix with down elevator worked a little bit prior to flap mod.

I set the aileron throws to max deflection (~2 cm) and 50% differential. Roll rate okay but not axial yet. Still working this out.

-Chad
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Old Feb 04, 2006, 02:30 AM
Detail Freak
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Harbor City, CA
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Is that 50% diff the actual measurement at the surface, Chad?

T
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Old Feb 04, 2006, 03:09 AM
It pays to be a winner
Keith R.'s Avatar
T-Town, AZ
Joined Jun 2004
1,733 Posts
Quote:
Originally Posted by slopemeno
I'd love to hear the following, as I'm very close to the first flight.
CG: How far back?
Throws
Spoilerons and elevator compensation
Differential, if any

Also:
What thread is the little nylon bolt thats begging to break, and what SAE thread are you guys replacing it with? 4-40?
What thread are the v-tail bolts?
That should cover it I guess. Any news on the carbon version?
The little nylon bolt on the wing is a 3mm bolt, and the 2 for the tail are 4mm bolts.

For the throws on mine rite now, about 1cm elevator up and down, and max aileron up with 66% diferential (about 2:1)

All i need to do now is fly the thing withi all my new mods...and my new radio

Keith
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Old Feb 04, 2006, 03:18 AM
It pays to be a winner
Keith R.'s Avatar
T-Town, AZ
Joined Jun 2004
1,733 Posts
Here are some pics of the reflex, camber,and elevator compinsation. Do any of these look like i went overboard with too much or not enough movement?

K
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Old Feb 04, 2006, 03:19 AM
more casual than stylish....
slopemeno's Avatar
Joined Jan 2003
6,985 Posts
I'd prefer to change over to SAE bolts whenever possible. Kinda hard to find a 3mm nylon bolt at 4pm in Bandon Oregon...

Also it doesnt hurt to have some commonality between planes. Most of my sheeted crunchies are either 1/4-20 or 10-32, to minimze what I have to carry in my backpack.
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Old Feb 04, 2006, 03:24 AM
Serenity now!
80SGliderDude's Avatar
W. Santa Cruz, CA
Joined Jun 2005
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Quote:
Originally Posted by target
Is that 50% diff the actual measurement at the surface, Chad?

T
It looks like ~20 mm on the up deflection and about 7 mm on the down. On my Evo9 it is 50% differential. Pretty close. I might go back to no differential. Any thoughts?

-Chad

Ed: that is measured at max stick movement.
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Old Feb 04, 2006, 04:18 AM
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BeeDee's Avatar
Fallbrook, California, United States
Joined Jul 2003
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lose the metric bolts... get rid of the nylon and go steel.... especially if you ever attempt to DS with it... I use a countersunk washer and bolt on the aft wing hold down bolt... Works great!

BD
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Old Feb 04, 2006, 10:47 AM
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San Diego
Joined Apr 2003
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my last darts cg was at 86mm, I removed .25 oz after maiden, get rid of the nylon, especially if you are going to ds, if you get in a good groove they will probably not last one flight

B
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Old Feb 04, 2006, 11:15 AM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
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Most of these newbies don't DS. They will want the nylon in there until they master the smooth landing...In my opinion.


Chad- if your rols aren't axial, leave in the diff, and set it up on one of the "Digi Adjusters" on the EVO, that way you can adjust it easily while you are flying.

T
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Old Feb 04, 2006, 11:32 AM
It pays to be a winner
Keith R.'s Avatar
T-Town, AZ
Joined Jun 2004
1,733 Posts
Chad- I think remember you saying you had snap flaps set up on your MD. About how much deflection do your flaps give with full up and full down elevator?

K
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Old Feb 04, 2006, 11:39 AM
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timmig's Avatar
Southern California
Joined Sep 2003
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Your camber and reflex look good to start--- I MAXED my aileron throws and put enough elevator in to keep from snapping it-- through trial and error on the slope, as when you move your CG--the throws will change. I tapped the rear hold-down hole to 440- then used a steel bolt. I also could bolt right into the fuse-- 1/2" lead rope that I got from Tom Copp-- sections that weighed 4oz each-- I could easily ballast up to 12 oz's that way with one long bolt. Once you find your sweet spot for CG--drill a hole at the fuse bottom there, add a few fiberglass circles about 1" in size around that area for strength-- and you're good to go! F3F Mach Dart!!! They fly very nice and with ballast-- very fast!
FWIW
Timmig

BTW-- snap flaps should only deflect DOWN-- you don't want them mixed with your down elevator-- only UP for pull through the turns. And you shouldn't need more than 1/8"
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Old Feb 04, 2006, 11:57 AM
Serenity now!
80SGliderDude's Avatar
W. Santa Cruz, CA
Joined Jun 2005
241 Posts
Quote:
Originally Posted by timmig
Your camber and reflex look good to start--- I MAXED my aileron throws and put enough elevator in to keep from snapping it-- through trial and error on the slope, as when you move your CG--the throws will change. I tapped the rear hold-down hole to 440- then used a steel bolt. I also could bolt right into the fuse-- 1/2" lead rope that I got from Tom Copp-- sections that weighed 4oz each-- I could easily ballast up to 12 oz's that way with one long bolt. Once you find your sweet spot for CG--drill a hole at the fuse bottom there, add a few fiberglass circles about 1" in size around that area for strength-- and you're good to go! F3F Mach Dart!!! They fly very nice and with ballast-- very fast!
FWIW
Timmig

BTW-- snap flaps should only deflect DOWN-- you don't want them mixed with your down elevator-- only UP for pull through the turns. And you shouldn't need more than 1/8"
Keith- Mine is similar to timmig's maybe a bit more. I'm still adjusting things.

My approach for ballast was different. I made a ply plate with a bolt coming up from the back side that was epoxied into the fuse under the wing. I didn't want to drill a hole in the fuse. I casted a couple of 8 oz lead plates with a hole in the middle. These are held in place with a 1/4-20 wing nut and washer. Other folks and I have posted on our various methods.

Can't wait till the winds kick up.

-Chad
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