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Old Nov 23, 2010, 07:20 AM
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The model will take a little bit of flying to get used to. And for those flying against it, you are out of luck in how it looks visually. Almost every other current F3b model looks almost the same at a distance in the air. The Fosa truely looks different with the high aspect ratio wing. It is almost starting to look like a real sailplane....

There are too many different things a F3b model has to do well to say any one design will be the best. But as everyone has seen with the Freestyler which looked kind of small and low aspect ratio, but performs well. I think the Fosa shows it's possible to go the high aspect ratio route too. But it is more of a challenge in construction.

In the past few years, I have flown a Ceres F3b, Tool, Ceres Lift, Tanga, Freestyler, Shooter, Cyril, and now Fosa. They are all a little different and may be better or worse for different pilots. And have different prices and levels of availability.

For tight radio installs, at the top is the Fosa and Radical. After that the Freestyler, then Cyril. Shooter, Tanga, and Ceres variations are spacious in comparison although the Tanga ballast tube installation requires careful planning.

I do like the fuse ballast in the Fosa and Cyril for contests. You can load the wing to what you think you need then put some extra in the fuse and quickly drop it if conditions look marginal.
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Old Nov 23, 2010, 07:38 AM
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The construction of the model is very stiff. It's tough to do with the high aspect ratio. Obviously you have seen the photos of the two wing joiners. They are much lighter in weight than you would expect. The two joiners allows for an extra web between the joiners to keep the joiner box in one piece. You can see the different webs looking inside the wing.

The top skin has some reinforcements around the servo area. It looks like a strip of carbon under the inside skin. I think the usual core might be removed from the top skin where the servo goes to allow for extra thickness. And the strips help keep the skin from distorting in that area. Servo frames for the RDS also help keep skin from moving.

The wing also has at least 3 ribs at different places along the span. This probably helps in torsional strength as well as keeping skin from distorting under load.

It's a nice planform so there is no funny tip to the aileron. Straight hinge line almost to the wing tip. Hinge is molded in. It's not a silicone hinge like on the Shooter or Radical.

I'm really impressed on what was done on the RDS box. It is a really good fit. I don't know how it's made but it feels better than the original Ceres Lift ailerons and Tanga setup. Cyril is the same way. I know everyone argues about degrees of freedom in RDS but the throw is good and the ball bearing close to the servo seems to work well.

The fuse is nice and light. And small. It's a bit flat on the top and bottom so it's small like the Radical but space is used a little differently. The "unique" battery pack allows for a little better shape to the front of the nose. And it requires very little nose weight to balance. The fuselage also has a number of carbon covered formers. So it doesn't have the finish inside of a bladder style layup. But it's stiff and light. The rectangular joiner on the V-tail is nice for stiffness on the small tails. It might look like a Cyril but it's smaller in cross section which is better for speed with the reduced surface area.
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Old Nov 23, 2010, 03:52 PM
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Carlsbad Ca
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Awesome reporting Mike

mmmm, new B plane in grass, mmmmmm


I ecco DK's sentiment.... it is best if you read it like Homer Simpson.....Mmmmmm Saaaaaawd

Curse the gravel
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Old Nov 23, 2010, 04:54 PM
the flying is good
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Gravel, what's that?
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Old Nov 23, 2010, 05:23 PM
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Gravel, what's that?
It's what is at the edge of the road when you turn off into tobacco.....
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Old Nov 23, 2010, 05:25 PM
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Since there are a lot of freestyler pilots out there in california. The Fosa wing is only 54,4 sq dm. A FS3 is 56,4. I worked through the wing loadings and when I was flying with the four 180gm pieces in the wing, the wing loading equivalent was 55% of your Freestyler ballast.
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Old Nov 23, 2010, 05:54 PM
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Mike,

What is the maximum ballast that the plane comes with? Wing and fuse.

-Aaron
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Old Nov 23, 2010, 07:42 PM
the flying is good
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USA, CT, Hamden
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Currently flying on turf for golf course greens, maybe a bit too short though.
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Old Nov 23, 2010, 08:14 PM
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Todays question - what wire did I use and where did I get it....

Alpha wire, part 2844/19 for the 24 gauge and 2843/19 for the 26 gauge. It's available from Newark Electronics. I use a drill to twist the three wires together.

http://www.newark.com/alpha-wire/284...ack/dp/02F9583

http://www.newark.com/alpha-wire/284...red/dp/02F9584

http://www.newark.com/alpha-wire/284...ite/dp/86K9023

http://www.newark.com/jsp/content/pr...g128&page=1230


Pick your favorite combination of colors. Prices have gone up on copper and the silver plating.
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Old Nov 23, 2010, 08:20 PM
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Originally Posted by Avaldes View Post
What is the maximum ballast that the plane comes with? Wing and fuse.
The stock ballast set is 4 - 180 gram pieces for the wing.

Fuselage tube takes up to 8 - 65 gram pieces. But that depends on your radio installation if you have room to get the ballast tube far enough to use all 8. Mine is back a little so I can only put 7 of them in there centered on the CG.

The 3-view says 2100-3400g. Also note that the wing area is only 54,4 dm2. This is less wing area than any other F3b model out there. Even the Freestyler has an extra 2dm2 of area. That's 843 in2 for the metric impaired. It almost starts looking like a real sailplane.....
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Old Nov 23, 2010, 11:35 PM
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Mike, are those the same pieces as the Cyril? I would assume so...

D
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Old Nov 24, 2010, 12:22 AM
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Ok, so looking at my Radical's, the wing area is 59.1 dm^2 or 916 in^2. With the stock brass ballast (all I have currently) I can fly at a maximum weight of 3.8 kg, or 8.38 lbs. This gives a max wing loading of 21.14 oz/sq ft. Wow, I didn't realize it was that high. The FS3 guys better check that their tungsten configurations aren't over the 24 oz/sq ft limit!

Anyway, per Mikes dimensions above, the max wing weight of the Fosa is 3.34 kg or 117 oz. And the max wing loading on the stock Fosa is 20 oz/sq ft....interesting.

PS- Ooops, the 24 oz/sq ft rule is for total surface area, so we need to include the projected horizontal area of the V-tails for that calculation...something I will leave to each of us to do.
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Old Nov 24, 2010, 06:28 AM
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Quote:
Originally Posted by Daryl Perkins View Post
Mike, are those the same pieces as the Cyril? I would assume so...

D
Only the fuselage is the same. There are only two pieces per side on the wing ballast. It is 15 mm square brass. The two wing joiners take a bit more space and the chord is narrower. I don't like the length of the pieces since if you had a wing wire that would slide out of the wing for ballast changes, it would have to be really long. On the other hand, the two pieces on each side will get you to a minimal distance weight anyway. When I do tungsten pieces, I'll do 3 per side.
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Old Nov 24, 2010, 06:42 AM
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Originally Posted by Avaldes View Post
Ok, so looking at my Radical's, the wing area is 59.1 dm^2 or 916 in^2. With the stock brass ballast (all I have currently) I can fly at a maximum weight of 3.8 kg, or 8.38 lbs. This gives a max wing loading of 21.14 oz/sq ft. Wow, I didn't realize it was that high. The FS3 guys better check that their tungsten configurations aren't over the 24 oz/sq ft limit!
Projected area....but all tungsten in a FS3 might be an issue.

Anyway, stock brass ballast in models is always too light for when the wind is really up. But alternatives are either socially unacceptable, handling lead, or pretty expensive except for those dedicated contest pilots, tungsten.


A Freestyler at 120% of stock ballast is about 21.7. Never had an issue with that weight. I don't know of anyone who has flown one with full tungsten everywhere. I can only put in a mix of tungsten and lead in mine.

I have launched my Ceres Lift with full lead ballast. There are 6 slugs per side. That is at 24.25 loading. The airfoil on the Lift is great at launching weight.
With the wind up on Saturday at team selections, I flew the Cyril with full lead in the wing and 6 pieces of brass in the fuse. A little over 62 ounces of ballast. So that's over 22 if you figure just wing area of 899.
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Old Nov 24, 2010, 11:26 AM
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I reload shotgun shells...I like handing lead...it gives me a tingly taste in my mouth

In all seriousness, if the proper precautions are taken, there is nothing wrong with handling lead. Tungsten is just that much cooler!
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