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Search: Posts Made By: jtt
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Forum: Private Flying
18th Oct 2020, 19:30
Replies: 33
Views: 8,583
Posted By jtt

From a height H you can see w = R * acos(R /...

From a height H you can see

w = R * acos(R / (H + R))

afar in each direction. R here is the readius of the earth (about 6360 km). The formula assumes that the earth is a perfect sphere (which...
Forum: Questions
31st Dec 2018, 19:49
Replies: 5
Views: 2,515
Posted By jtt

Take a tin can and put and cover the top with an...

Take a tin can and put and cover the top with an rubber foil, sealing it air-tight. If the pressure in the tin can is equal to the outside pressure the foil will be flat. If you take it to higher...
Forum: Rotorheads
21st Jan 2018, 11:12
Replies: 11
Views: 6,300
Posted By jtt

It's a joke - according to the (special) theory...

It's a joke - according to the (special) theory of relativity the mass of an object increases with it's speed - the nearer it gets to the speed of light the heavier it becomes, so it takes more and...
Forum: PPRuNe Problems or Queries
25th Mar 2017, 22:42
Replies: 18
Views: 3,398
Posted By jtt

Using HTTPS does just that - it's completely...

Using HTTPS does just that - it's completely transparent to the user of the web site. If done correctly most users won't even notice when a site switches from HTTP to HTTPS. But since they don't...
Forum: PPRuNe Problems or Queries
17th Mar 2017, 21:09
Replies: 18
Views: 3,398
Posted By jtt

But that's the fundamental problem! Many (most?)...

But that's the fundamental problem! Many (most?) people do use the same password (or with only minor and easy to guess modifications) for a lot of sites. You can preach to them until you're blue in...
Forum: PPRuNe Problems or Queries
17th Mar 2017, 00:23
Replies: 18
Views: 3,398
Posted By jtt

A quick look at the sources of the PPRUNE web...

A quick look at the sources of the PPRUNE web pages show that the password doesn't seem to get sent out in clear text. Instead a "hash" value is created from it and that's what is send to the PPRUNE...
Forum: Military Aviation
15th Mar 2017, 22:20
Replies: 30
Views: 10,473
Posted By jtt

I may look like a spoil-sport and I'm not a...

I may look like a spoil-sport and I'm not a (mlitary) pilot but merely a programmer. But the question you should ask yourself is how important are those data to you? If you can say without hesitation...
Forum: Tech Log
9th Jan 2017, 10:58
Replies: 37
Views: 9,081
Posted By jtt

Well, if you load an infinite amount of fuel the...

Well, if you load an infinite amount of fuel the airplane becomes infinitely heavy. So you need infinite thrust just to get it to move. And for that you need an infinite amount of fuel - all the fuel...
Forum: Tech Log
19th Jan 2016, 20:34
Replies: 8
Views: 2,337
Posted By jtt

> How long till you hit that cone, at mach .78?...

> How long till you hit that cone, at mach .78? But I do wonder myself...
Probably after the sound has left, moving at mach 1.0;-)
Forum: Tech Log
31st Jan 2015, 22:05
Replies: 48
Views: 11,147
Posted By jtt

Me neither anymore;-) (Sorry, BTW, for the long...

Me neither anymore;-) (Sorry, BTW, for the long delay, but I hadn't looked at this thread for some time.) Actually, the speed of sound does not depend on the speed of the source, that's where I got...
Forum: Tech Log
22nd Jan 2015, 16:41
Replies: 48
Views: 11,147
Posted By jtt

Post Not a very good idea, sorry

There's nothing the Doppler effect will help you with here. It's due to a velocity difference between the sender and the receiver and doesn't depend on some surrounding medium (which isn't even...
Forum: Freight Dogs
6th Mar 2014, 21:49
Replies: 8
Views: 2,988
Posted By jtt

Probably a similar way of thinking - I found that...

Probably a similar way of thinking - I found that when trying to come up with an intuitive explanation it's often useful to consider "extreme cases" that are really obvious and then start arguing...
Forum: Freight Dogs
6th Mar 2014, 21:30
Replies: 8
Views: 2,988
Posted By jtt

Hi, I'm not a loadie or anything related...

Hi,

I'm not a loadie or anything related to aviation, just a simple-minded physicist, so take this with a grain of salt... I'd say you're absolutely right with your 667kg/m^2 - that's the...
Forum: Tech Log
19th Apr 2012, 10:38
Replies: 9
Views: 8,476
Posted By jtt

As others have already pointed out you don't have...

As others have already pointed out you don't have much power available on a satellite. Unless you use something based on nuclear energy your only alternative is solar power (you don't want to shoot...
Forum: Tech Log
4th Feb 2012, 22:41
Replies: 16
Views: 2,987
Posted By jtt

If the brakes are on and the plane doesn't move...

If the brakes are on and the plane doesn't move it's like having thrusters bolted to the earth: you push some air in one direction and what the thrusters bolted to (the earth) must go in the other...
Forum: Tech Log
11th Oct 2010, 01:40
Replies: 46
Views: 9,025
Posted By jtt

When the energy of the aircraft doesn't change...

When the energy of the aircraft doesn't change then no work has been done on it per definition (at least in the language of physics). And there is neither change of kinetic nor potential energy of...
Forum: Tech Log
8th Oct 2010, 14:50
Replies: 46
Views: 9,025
Posted By jtt

if you look for the energy you can't think about...

if you look for the energy you can't think about the aircraft alone - it's flying throught the air and what happens to the air must also be taken into consideration. You are correct that in level,...
Forum: Rumours & News
31st Aug 2010, 13:56
Replies: 64
Views: 17,615
Posted By jtt

LIDAR?

Could that have been a LIDAR experiment and getting "hit" was just bad luck? As far as I know you need to get a permission before you do that kind of stuff, but then at the physics institute I was...
Forum: Aviation History and Nostalgia
31st Oct 2008, 12:44
Replies: 31
Views: 6,093
Posted By jtt

Sorry, but I've got to rain in on the parade a...

Sorry, but I've got to rain in on the parade a bit. Let's start with the "beauty" of Tempelhof. It simply doesn't exist. The building is ugly as hell and is a typical example of Nazi-architecture,...
Forum: Tech Log
27th Feb 2006, 17:41
Replies: 66
Views: 12,678
Posted By jtt

You shouldn't try to think of an aircraft flying...

You shouldn't try to think of an aircraft flying due to either Bernoulli or N3. Basically, there are two fundamental laws of physics that always need to be obeyed. The first one is conservation of...
Showing results 1 to 20 of 20


 
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