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Pulse Jet LSR


jaxenro

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2 hours ago, jaxenro said:

Where would you place the front wing? Is there any danger of going too far forward and causing it to dig the nose in and flip over tail to nose? I don’t need traction for power just steering. How about even with the front wheels?

Something to bear in mind here from an actual engineering perspective...you don't necessarily need "downforce" to achieve good steering response and forward traction at speed.

What you DO need is an absence of "lift".

Creating downforce with any kind of "wing" or airfoil-shaped device inevitably creates drag as well. Drag force is proportional to the velocity for a laminar flow and the squared velocity for a turbulent flow. Simply stated, this means the power requirements to push the vehicle at speed will increase dramatically with increasing speed, and REALLY dramatically if a non-laminar flow airfoil is used.

Laminar flow airfoils were well understood at the end of WW II. The P-51 Mustang had laminar flow wings.

But whatever some "guys" would come up with, unless one of them had recent aerodynamic engineering experience, would likely be a draggy mess.

Sure it looks cool to have an upside-down wing stuck over the front of the car.

But this is one of those areas where sound engineering dictates the KISS principle...keep it simple, stupid.

The primary goal of developing the shape of the nose should ideally be to ELIMINATE the possibility of a cushion of air developing UNDER it, rather than tacking on extraneous flippers and fins to COMPENSATE for it.

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On 11/23/2018 at 6:56 AM, jaxenro said:

Where would you place the front wing? Is there any danger of going too far forward and causing it to dig the nose in and flip over tail to nose? I don’t need traction for power just steering. How about even with the front wheels?

Placement is only critical in that you need it in clean air.  The wheels will cause a lot of turbulence around them so in front of them would be preferable and the higher the better.  Size and shape  of the wing is going to determine the amount of lift/downforce you generate and the sensitivity.  The larger the wing the more force for a given change in the angle of attack(the angle between the cord of the wing and the angle of the air).  So a smaller wing would be less likely to develop too much lift/downforce but by the same token, if you don't have a large enough wing, you will not have enough to keep the nose on the ground.  Best to use a SWAG measurement on the model.  (SWAG = Scientific  Wild A## Guess)

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  • 3 weeks later...

So I finally got the base model in the mail from HK. My thought was to make wheel covers like the Stutz LSR car from the wings but the chord isn't big enough to cover nor are they thick enough so i am looking for a plan B. Pics to follow it is really a simple kit for the price not a lot of parts.

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  • 3 weeks later...

Lot of the weight is on the back end the front section was the 1,000 kg warhead which I think they are leaving out but I will go with the forward position

I am working on mounting the rear stabilizer and elevators on the nose to keep it down running the elevators in tandem

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14 hours ago, chris chabre said:

Wheelbase is your friend at high speed

That is a solid thought.  The shorter the wheel base, the more sensitive the vehicle is to small steering inputs.  For very high speed cars you want the wheelbase to be as long and possible the control movement to have a minimal input(e.g. most amount of steering wheel imput for the minimum wheel deflection).

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  • 2 weeks later...

Not that any of this will show but I did add some seat belts and stuff and gussied up the control panel a little. I am sort of trying for a rough edge look as they tacked in some sheet aluminum to cover parts of it

I cut out and built the front wheel well also I will be closing it all up and painting the main body over the weekend

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Edited by jaxenro
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