What to use to make a mold?

On 24 Mar, 23:05, AK wrote:

Ian, I create a mold first then I pour lead into the mold. Later I
break the mold up and I use fiberglass to cover the lead so it is
trapped and I am not exposed to lead dust.

I don't think you need worry about lead dust. I used to fly a Club
Libelle (not a Libelle owned by a club) which had a 1/4" sheet of lead
under the pilot's seat - if that's the sort of thing you need then why
not glue a thin layer of energy absorbing foam to each side and make
yourself a very heavy cushion?

Ian

At 15:03 25 March 2009, The Real Doctor wrote:
why
not glue a thin layer of energy absorbing foam to each side and make
yourself a very heavy cushion?

And have it hit you hard in the back of the legs under high g if you plant
the glider?

Always a good idea to have any necessary forward of CG ballast in front of
the pilot.

On Mar 25, 11:15*pm, Z Goudie wrote:

Always a good idea to have any necessary forward of CG ballast in front of
the pilot.

That may depend on whether the objective is to adjust CG, or to
increase flying weight.

Andy

On 26 Mar, 06:15, Z Goudie wrote:
At 15:03 25 March 2009, The Real Doctor wrote:
why

not glue a thin layer of energy absorbing foam to each side and make
yourself a very heavy cushion?

And have it hit you hard in the back of the legs under high g if you plant
the glider?

He has said elsewhere, I think, that this is for placing under him.
And he could fasten the cushion down.

Always a good idea to have any necessary forward of CG ballast in front of
the pilot.

In general yes, but surely it depends entirely on the glider's weight,
balance and limits?

Ian

On Tue, 24 Mar 2009 19:20:32 -0700, AK wrote:

Is this for a private glider of for use in a club glider?

IOW, what are your options for placing the weight and for securing it?

- if you have to sit on it then sheet bent to match the seat pan
would minimize its effect on your headroom, but securing it
properly could be difficult.

- putting a block of lead in the nose is safest (its on the scene of
the crash before you get there), and securing it may be somewhat easier,
particularly if you use sheet lead and the securing bolts also hold
the sheets together. Last but not least the forces you need to
anchor it against would be less (launch acceleration, sliding back
during a winch launch)


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

At 14:35 26 March 2009, The Real Doctor wrote:

He has said elsewhere, I think, that this is for placing under him.
And he could fasten the cushion down.

I would be worried about the design strength of any fastenings to flimsy
seat pans during high g impact decelerations.

In general yes, but surely it depends entirely on the glider's weight,
balance and limits?

If it's for C of G positioning then the further forward the less mass
needed. You may exceed the all up weight limit with sufficient mass at
the seat lever arm for CG positioning; also I'd not be particularly happy
about speed performance ballast I couldn't get rid of in the air if I
ended up low and scratchy!

On 26 Mar, 21:00, Z Goudie wrote:
At 14:35 26 March 2009, The Real Doctor wrote:

He has said elsewhere, I think, that this is for placing under him.
And he could fasten the cushion down.

I would be worried about the design strength of any fastenings to flimsy
seat pans during high g impact decelerations.

I'd be concerned about doing them right...

In general yes, but surely it depends entirely on the glider's weight,
balance and limits?

... I'd not be particularly happy
about speed performance ballast I couldn't get rid of in the air if I
ended up low and scratchy!


Having spent 5 hours 4 minutes sitting on a 1/4" lead sheet in a Club
Libelle below 2000' in France, I can assure you that "low and
scratchy" takes on a whole new meaning.

Ian