Theoretical question about wingless flight with a flight pack

  • #1

Main Question or Discussion Point

What is the power to weight ratio required from a wingless augmented portable flight pack (jetpack) so that it can enable flight horizontally?

Assume that the jetpack and the user both weigh 300 pounds combined.
 

Answers and Replies

  • #2
Anachronist
Gold Member
82
23
Well, if the power to weight ratio is above 1.0, it can fly horizontally. How fast horizontally depends on the ratio.

The horizontal component of thrust that is possible is given by the Pythagorean theorem, where the total thrust is the hypotenuse and the weight is one vertical side:
$$F = \sqrt{T^2-W^2}$$
where ##F## is the horizontal thrust, ##T## is the total thrust, and ##W## is the total weight.

So if the jet pack thrusted just 301 pounds, it could be tilted ever so slightly to impart a slight horizontal force to propel the wearer horizontally, but slowly.
 
  • #3
CWatters
Science Advisor
Homework Helper
Gold Member
10,529
2,296
I doubt humans make very good "lifting bodies" so +1 to what Anachronist said.
 
  • #4
727
168
I doubt humans make very good "lifting bodies" so +1 to what Anachronist said.
I guess it depends on what you mean by very good. A skydiver can reach horizontal speeds of 19 m/s while vertical speed is about 72 m/s, is that bad, good? Not good enough to land I suppose :-(

Cheers
 
  • #5
CWatters
Science Advisor
Homework Helper
Gold Member
10,529
2,296
Any glide slope less than 1:1 isn't even bad.
 
  • Like
Likes cosmik debris
  • #6
Anachronist
Gold Member
82
23
Any glide slope less than 1:1 isn't even bad.
That depends on the speed at which you hit the ground. :)
 

Related Threads on Theoretical question about wingless flight with a flight pack

  • Last Post
3
Replies
63
Views
21K
Replies
1
Views
3K
  • Last Post
2
Replies
33
Views
2K
  • Last Post
Replies
14
Views
4K
  • Last Post
Replies
15
Views
8K
  • Last Post
Replies
3
Views
38K
  • Last Post
Replies
18
Views
3K
  • Last Post
Replies
6
Views
970
Replies
4
Views
2K
Top