How much ballast and what conditions

[ORRich]

I have a 1.5m Elf slope that I'm about to maiden - it's not quite ready but I went to scout the flying site and winds here will be in the 10-15mph on a 'normal' day - currently the weight of the Elf is around 645g - I'm open to trial and error, but it would be good to get a recommendation on a good starting weight - 3o grams? 20? thanks in advance

 

[Konrad]

With the Elf if you need ballast it might be best to use another ship. The amount of ballast is highly dependent on the slope. I’d think 200 grams is about the max. I’d think about using 20 to 50 gram slugs. What does your ballast tube look like?

 

[ORRich]

No ballast tube yet - not sure how it compares to the Mephisto fuse, but the Elf fuse is tight

 

[Konrad]

Having added a ballast tube to the larger Mefisto I wouldn’t bother with a ballast system for the Elf. The Elf is a nice light lift ship. If the winds are so strong as to need ballast it is time to select another glider.

 

[ORRich]

Thanks Konrad - that makes sense to me

 

[Wayne]

We had some guys in So Cal with really heavy Elfs. Don't even know how you can achieve this, but they did. Their planes turned a good bit of speed. I was surprised. They had ballast tubes in them.

I still think it best to keep these planes light, they shine nicely in that arena.

 

[ORRich]

Well, finally after a long absence on this site and what seems like an interminable summer, I got to maiden the Elf - here is a very short clip - there was only about 5 kts of wind at best, so I was about to scrub the flight, when Wayne's words kept reminding me that "the Elf will fly in very light winds" - total of 4 flights, which were the first real RC slope soaring flights in literally 30 years! My hands were pretty shaky - she weighs in around 750g and the CG is about 72mm from the LE - very happy with her characteristics as the CG placement and trim seemed to be spot on - about an hour before, while I was getting it ready at home, I dropped her on the tail and broke the fin and rudder - but I managed to fix it and get her to fly -

 

[Doc J]

Fly the plane up to 50 feet. If it can go higher you need ballast.

Doc.

 

[purview]

if it lifts you can add more. the wing loading isn't a problem you just need more flying speed. the thing with ballast is that you have to land the total thing, that means more abuse of the structure, materials and bonding.

so dependend on plane and flying style and on flying skillz it should be no problem to fly with twice the model weight (yours from 750g to 1500g), but nature of lift is not a constant, that is the gambling factor you have to deal with.


5 slugs with 50g each is a good starting point, somewhere near the CG

 

[Konrad]

Rich, she looks like a perfect light inland slope ship!

As to ballast this is NOT an F3F racer! Ballast her to deal with the turbulence of the flying site. That generally means less is better. There is NO set rule as to what amount of ballast to use. If you have good lift and can't make a nice axial roll, add ballast. If you can't loiter at the lip remove some ballast.

I have a Mefisto that I can ballast to the point that the wings will flex and look like a sine wave! This is ridiculous and means that if flying in that kind of wind I need to change ships!

The Elf is a sweet plane for low lift sites. I like to keep some ballast just for the flexibility it offers. But really if I need to add ballast, I'd rather pull another ship out of my quiver.

 

[Wayne]

Not sure why people are commenting on ballast.

Looks like a good flying plane and a good pilot. Enjoy her!!

 

[Konrad]

Thread heading

 

[ORRich]

Thanks Wayne - the thread was an original post a couple of months back on ballast recommendations but then I posted the video a couple of days ago - so it's normal that people assume the question of ballast is still a question, when all I was doing was posting the maiden video - I'll take the lump on that one

 

[Doc J]

Not sure why people are commenting on ballast.

Looks like a good flying plane and a good pilot. Enjoy her!!

Yeah man...

We 'don need no stinking ballast!

Doc.

 

[Hill Hobbit]

As the Elf has a very light fuz layup, I wouldn’t really consider putting ballast in one. What does make a difference though is a reflex/speed flight mode, where the ailerons are both raised about 1mm above neutral. I’ve built a couple of these models, and they are good at stock weight up to about 20-25mph headwind. Above that, the folks that have them fly something else.
A thermal/climb mode, with the ailerons drooped around 1 to 1.5mm also helps in light lift.

 

[Hill Hobbit]

I’m guessing your Elf might have the HN1033 wing section, which is great for light conditions. An option to go a bit faster is to use the s6063 section wing (which you might already have).

 

[ORRich]

I’m guessing your Elf might have the HN1033 wing section, which is great for light conditions. An option to go a bit faster is to use the s6063 section wing (which you might already have).

It’s the 1033 with cross tail

 

[Hill Hobbit]

The 1033 wing is marketed as the ‘thermal’ version, whilst the s6063 is branded as the sloper. The two I built were both 1033 foils, but still would fly inverted all day long, do nice outside loops etc. Not much in it really, I think. The same goes for the Mefistos I’ve built. They have the ‘thermal’ foils, so will fly well in very light lift and accelerate very quickly to do most aerobatics. Being so light (both around 970/980g) though, they don’t retain energy, but are sweet models up to around 20/25mph. With cut back trailing edges underneath to get more down flap throw than stock, they are beautiful to land.
Here’s the 2nd Elf in my frosty yard:

 

[Wayne]

My Mefisto has the slope airfoil. I'd still say she is a great light wind plane. When I first had her flying a let a bunch of different pilots fly here while I recorded video. I always thought it was interesting that each pilot flew her differently and all liked here. Some floated here around, some liked to zoom up and down and other doing Acro. You could actually tell in the video when the plane was handed off as the flying style changed that much. I think that says a lot for the Mefisto. It is a well rounded plane. So is the Elf, it will do many things very well, and I really love the looks of these planes.

 

[Hill Hobbit]

The Serafin is really good as well. It’s one that I regret selling, so as I’ve got a kit stashed, I might well work on it when the weather really cools down. They stay up in a flea f- -t!