Funny how things seem to develop. The Ballast box.

[Doc James Hammond]

Hey Guys,
Flying F3f planes or in fact most slope planes these days you need to carry ballast, lugging it all over the topography which is par for the course. Actually, pretty much anything will do to contain it as it can't go far.

Its only when you have to put it in the hold of an airliner plane or something that it gets a bit of a problem as the the weight in such a compact bunch makes it quite damaging should it somehow break loose. I have tried various fishing boxes made of plastic etc and some of them were Ok but all broke eventually.

Since I now use two types of ballast: 19mm round Tungsten Copper slugs, and recently 20mm square brass ones the problem has doubled - so I decided to make a bespoke ballast box - or in fact two fo them, one for each type, and also to hold the wooden spacers as a set.

So here is the result.

Wood incidentally, is recycled Vietnamese Red Cedar.

Cheers,

Doc J.

 

[Doc James Hammond]

'Course, then I got carried away...

How about a box for the ballast boxes? Mused I.

Planes come and go, but a really neat model flight box...? Hmm

Modelled on a toolmakers/master machinists tool cabinet, only a bit smaller at about 75%, this is what happened...

There ensued a mad week of hacking at some nice red cedar I'd had for a while, that was looking for a worthy project - I'd salvaged the wood from a broken old "Made in Vietnam" (It said so on the bottom) kids desk that I found by the side of a road. At the time it was made, about 80 years ago, it would have been cheapo kids furniture, but now the wood is very scarce, and its obviously well seasoned!.

The two small boxes in the bottom of the cabinet are the ballast boxes from my post above - see how neat they look?

The opening chest area at the top of the cabinet is to hold the plane fuselage crutches (Not shown, I'll post them later) that screw to the sides of the cabinet so you have somewhere to work on your plane at a decent height. I also added a couple more screw fittings at the bottom of the case to take stabiliser outriggers should they be needed.

Missing are the two hasps that will hold the opening top to the rest of the cabinet - my local hardware store had run out! I'll add them later.

Useful Huh?

Doc.

 

[Wayne]

Super nice! Sean commented that he really likes it, and looks somewhat familiar. LOL

Speaking of ballast, I am in the process of ordering in more and I am looking at a few new sizes. Was not sure what the sizes are for the wings in your planes. If you can give a safe dimension I can see how bad the pricing will be for custom slugs. Will be from tungsten. I usually have to buy a bunch to get a decent price.

I don't know what is wrong with me, but I seem to have a weakness for ballast materials. We now sell Tungsten, Lead and woodsmetal and I am still adding to the collection. LOL

 

[Doc James Hammond]

Active uranium, Wayne - its the only way to go for night flying...

I'll get all the sizes to you be eemer.

And now for something completely different...the model box with ears!

Cheers,

Doc.

 

[Wayne]

OK- I'm sold, I'll take 100 of them.

 

[Doc James Hammond]

I could make a (very) few if people wanted them.

Say 3 or 4, but no more.

Doc.

 

[Doc James Hammond]

Super nice! Sean commented that he really likes it, and looks somewhat familiar. LOL

Speaking of ballast, I am in the process of ordering in more and I am looking at a few new sizes. Was not sure what the sizes are for the wings in your planes. If you can give a safe dimension I can see how bad the pricing will be for custom slugs. Will be from tungsten. I usually have to buy a bunch to get a decent price.

I don't know what is wrong with me, but I seem to have a weakness for ballast materials. We now sell Tungsten, Lead and woodsmetal and I am still adding to the collection. LOL

Hi, Wayne,
as you know I use different ballast for wings and fuselages.

For Fuselages: For Wings

Stormbird = 20mm = 12mm
Aresti 80 = 20mm. = 16mm
Aresti 108 = 20mm. = 20mm
Schwings = 20mm. = 12mm
Gremlin = 20mm. = None (Inside the wing joiner)
Redshift = 20mm SQUARE. = 20mm x 12mm Rectangular.

Thats about it. The Redshift can also use round ballast in the fuselage but I need to know about it on ordering.

Also, the Redshift has one unique ballast trick because you can put ALL of the ballast to get to FAI limits in the wings, or ALL needed in the fuselage - or of course half in each.

Cheers,

Le Bonne Docteur.

 

[Wayne]

Ok - Looking at getting some custom stuff made up. Any idea on a good length for the Redshift if I get some tungsten bricks made up? I'd probably undersize the dimensions a half mm or so to be safe on the fit. Grinding tungsten does not work well!

 

[Konrad]

0.5mm (0.020" old school) sounds a bit, much rattle a lot.

Doc. what tolerance do you have on the production on these balast "tubes"? I'd think 0.15mm to 0.25mm (0.006" to 0.010" ) would produce a nice working clearance. Now I did see Doc fighting a wing joiner on his last visit. That was no fun.

 

[Doc James Hammond]

Ok - Looking at getting some custom stuff made up. Any idea on a good length for the Redshift if I get some tungsten bricks made up? I'd probably undersize the dimensions a half mm or so to be safe on the fit. Grinding tungsten does not work well!

Hi Wayne - I use 35mm always for my fuselage ballast - all the same square or round.

I make the tubes oversized to normally the correct bar size fits OK.

Cheers,

Doc.

 

[Doc James Hammond]

0.5mm (0.020" old school) sounds a bit, much rattle a lot.

Doc. what tolerance do you have on the production on these balast "tubes"? I'd think 0.15mm to 0.25mm (0.006" to 0.010" ) would produce a nice working clearance. Now I did see Doc fighting a wing joiner on his last visit. That was no fun.

Normally I make them about 0.5MM oversized.

You have to remember to take the edges of the bar - square or round - as otherwise it will catch.

Wayne has a Redshift ballast set that I made which will fit well and gives a good example of how it should be - these are brass and as Wayne says Tungsten is a bugger to cut or grind, and the only thing that will help is (believe it or not) Carbon Tetrachloride.

Cheers,

Doc.

 

[Konrad]

I seem to recall the oversized compartments. This is a very good Idea as it allows us the end user to build up the clearance by painting the weights with enamal paint (0.15mm per side).

 

[Doc James Hammond]

I seem to recall the oversized compartments. This is a very good Idea as it allows us the end user to build up the clearance by painting the weights with enamal paint (0.15mm per side).

I don't think I'd do that Konrad - but each to his own.

I normally try to make the tubes/blocks/sizes so that it relatively easy to find a similar imperial/metric size.

12mm = 1/2" - this is the only size where the imperial is larger (12.7MM = 1/2")
20mm = 3/4"
20mm x 12mm - 3/4" x 1/2"

It might be necessary to remove some stock from the 1/2" type, but so far I have found it seems to fit OK in my tubes.

Cheers,

Doc.

 

[Konrad]

What issues would you see with tightening up the clearance? There needs to be clearance but for 50mm to 75mm long ballast I don't see the need for .5mm clearance.

There shouldn't be any moisture expansion issues with the materials used.

Loose ballast makes a heck of a racket as the plane hits the shear layer while DSing.

 

[Doc James Hammond]

Hi Konrad - I use tension - or rather compression actually.

Use a medium tension spring or a spring like EPP blob (Which I prefer) to compress the ballast in the tube.

Look at the pic.

Simple, cheap and works a million times better than all the screw, nut and bolt arrangements I have seen so far.

Cheers,

Doc.

 

[Konrad]

That works real well controlling axial movement. I seem to hear a lot of rattling when there are more than two joints (three slugs) in the tube. I’m assuming that this is radial movement. Hence my concern about clearances.

I like that your tubes are oversized allowing me to build up the slug to achieve a tighter clearance. I like hard enamel as it is easy to sand back down when I take up too much clearance. Also it is easy to reapply as the surface wears. Your nice boxes should minimize a lot of that wear !

 

[Doc James Hammond]

I wonder what would happen if someone contact adhesive'ed some soft rubber caps on each end of the slugs...

Actually they would only need to have one end "rubberised"???

Cheers,

Doc.

 

[Wayne]

If you have ever had a slug stuck in a plane, you will happily live with some tolerance. Drilling a hole in your plane to push out a slug really does suck. This can be an issue after some abuse to the plane has occurred. With softer metals , it is easy to drop a slug and cause fitment issues, only to be discover after you push the darn thing into a tight tube.

 

[Konrad]

If you have ever had a slug stuck in a plane, you will happily live with some tolerance. Drilling a hole in your plane to push out a slug really does suck. This can be an issue after some abuse to the plane has occurred. With softer metals , it is easy to drop a slug and cause fitment issues, only to be discover after you push the darn thing into a tight tube.

Yes, but 0.5mm (0.020") is too much in my book.

 

[Wayne]

Tungsten in an unforgiving material and I would need to see the tolerances from our supplier, but yes, I hear you. I know of some folks that did a group buy for tungsten for some go fast plane. They finally got the stuff in and discovered it was all too big, but when they checked, it was within tolerances the manufacturer had informed them of. They then spent a lot of time trying to find a machine shop that was willing to grind it down. One shop that should have known better gave a reasonable quote to grind it down to fit the planes. Soon that shop discovered the nightmare they had signed up for. They finished them all, but broke many of the bars during the grinding process. (It was not an alloy!)

I have 1mm of clearance on some of my planes. Does not bug me..