Liftoff (FW) build diary

[Mouldy]

I understand what you mean and technically there's nothing in the rules that states "it must be a ball valve" however this is the standard here.

For the weight of the mechanism your planning you could easily fit a low pressure ball valve.

[Liftoff]

Ok point taken, separate valve it will be.
On a different note, started building the gearboxes, look good so far...

[Liftoff]

Can someone to do some double checking for me please - I want to use a 9oz Co2 main tank and would like to know the max number of flips it can possibly give.
I want to regulate the operating pressure to a range from 19 to 24 bar max. I'm using two rams with a combined volume of 0.436 Lt.
I calculated this would give me a max of approx 13 flips at 24bar...is this close to reality, and would that be near enough for a round?

[maddox10]

9oz carries 138 liters of gas @1 bar. @24 bar that is 5.75 liters.

5.75/0.436=13 actions.

But, you're fogetting losses in the setup, and inefficiencies. If you get 10 decent flips, the setup is well done.

And I doubt that it will be enough in a fight with an experienced opponent.

[Liftoff]

What would you rate as a decent amount of flips? Keeping in mind it's a feather and constrained by weight and space, that's why I was drifting towards a 9oz tank, a 12oz tank would be the maximum I could go up to. ..

[maddox10]

If you can't get an opponent OOTA with 10 flips, it will become an endurance fight.
Can your machine drive upside down?

[Liftoff]

Can your machine drive upside down?

Unfortunately no, worse than that, the way it's designed, when it runs out of Co2 the flipper blade will always be in the open position. So I need to leave some reserve Co2 to keep it closed.

[maddox10]

Better to use spring(bungee) return, that saves gas and gets the flipper in default closed.

[Liftoff]

The thing is I'll be using a spring as the main force to deploy the flipper the pneumatics to cock the spring. It's still at design stage but before starting the actual build I want to make sure it's within the weight limits

[Liftoff]

Untitled.jpg
Is there a way to calculate what throw would this set up be able to produce?
The pneumatics would run on 55bar.

[mark_m]

flip height

How free flowing the gas supply is has as much influence as the geometry. Small tank, pipe, regulator and valve will restrict gas flow and you wont get full pressure. The flipper arm mass has a small effect too, as does where the opponent is on the arm. You could get from 30cm to 3m depending on the system efficiency.
Assuming a very light arm and perfect pnuematics:
H = P*(R^2)*T/10/M
H=flip height
P = pressure in pascals
R = cylinder radius in metres
T= cylinder throw in metres
M = opponent mass in kg.
but that will only tell you the upper limit. The pressure drop will be significant.

[Liftoff]

Let's leave the efficiency of the pneumatics out of the equation for now, what I'm after is the geometry. With a ram stroke of 38mm and a force of approx 1000kg will the geometry work?
I'm wondering if I put too much negative mechanical advantage, and can't figure out how to get approximate figures.

@Mark, your formula seems to do without leverage ratios

[maddox10]

The flipperarm will push the extended rod down and lock it, making retracting difficult or even impossible.

[Liftoff]

It will be pneumatic retract ram Mario so should not be an issue, what do you think in terms of flip height tho?

[maddox10]

Going from real life examples with rams in that size range you get this kind of flips.

Starting on 18 seconds.

https://www.youtube.com/watch?v=HM349ORrbq4