Member postings for Jacob Worthington

I had disregarded the mass of the water since I want the rocket to glide to the tune of the weighted nose using the momentum of the takeoff. And also the water will be expelled in literally less than a second.

Still a consideration?

Jacob

Fantastic ideas and suggestions. I've managed to design and laser cut thin plywood wings. Which should be stronger and better shaped without compromising too much on weight. However before I secure the wings to the main frame, I was wondering if there's a formula that calculates the optimal position of the wings(fore and aft) with regards to the balance between the centre of mass and centre of lift. That the plane neither stalls or nose dives. I imagine that it's application in this instance may be difficult to configure since acceleration is a consideration.

Really, many many thanks,

Jacob

Thanks for your ideas, very useful having other opinions. Yesterday I tested my prototype design. A balsa wood frame covered in tissue and shrinking dope. Weighted in a way that flew horizontal with no water in it since at 110psi all the water will be expelled in less than a second. The wing design I went for was a medium swept wing to cope with the acceleration, and a tail to give directional stability.

Filled with 550 ml of water, and at 110 psi at an angle of 45degrees launched with the wind, the thing went some! One wing and tail wing broke off in an upward direction suggesting too much lift(which is good) and not strong enough materials. Regardless it had a maximum altitude of about 25 metres before crashing down at the other end of the park (some 100 metres)

I have in mind to use software to laser cut 3.6mm ply wood as a substitute to the balsa frame, including additional supports to increase durability. Is there a stronger substitute to using tissue paper and shrinking dope that doesn't compromise weight?

Nice ideas, I like the idea of a coil that widens the aperture or the bottle neck over time, but how to make this without the whole lot flying out in one hit after the trigger mechanism is released? Spring loaded pop-out wings have been considered, and despite my love for thunderbirds I'm afraid it will have other weaknesses, and certainly difficulty during manufacturing.

Thank you Michael. I was hoping to go for more of a powered aircraft since it will travel further horizontally than a rocket launched mortar style. So for this distance long glider wings may be suitable, however the longer the wings the greater the moment and leverage the air resistance will have. Maybe I can compromise by having a long flat triangular wing like on the space shuttle or Vulcan bomber. I suppose it will depend on what materials I use for the wings but I'm afraid the shear lift could cause the wings to snap off. It may be subsonic but it packs one hell of a punch.

Many thanks,

Jacob

Hello,
For a mechanics project I've been asked to design a bottle rocket.(pressurised air using water as propellant). The aim - to get the rocket as far horizontally as possible.

Now, for maximum flight time glider wings may be ideal, but won't survive the initial acceleration of the rocket considering I'm using a 2litre bottle at roughly 110 psi (subject to change).

For this reason I'm wondering what measures I can put in place to limit the acceleration of the rocket. Ideally the rocket/plane will accelerate slowly until it reaches maximum velocity. Perhaps a valve that regulates the flow of expelled pressures? Or a way of restricting the flow in a way that decreases as the pressure decreases.

Bit of a long shot but appreciate any advice.

Many thanks,

Jacob