1 horse power and 1 horse power is not 2 horse power. Please help needed.

[joe indian]

Hi guys, I need help, please.

I have created 2 interplanetary tugs which each has delta V = 5000 m/s. On LKO (80km) I connected them paralel using docking ports and third T like struts construction, and naively supposed, that now I will have big horse with delta V = 2 times 5000 m/s, but it does not happend. I have still the same delta V. Can any one help me how to connect on LKO N independent tugs to have N times delta V? All suggestions or advice is appreciated. Thanx a lot. Joe Indian

Bellow is schematic picture what I tried to tell

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/---------\ /--------\

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|-------| |-------|

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Edited September 6, 2013 by joe indian

[TheDarkStar]

Delta-v does not act like that. It's not a sum, it's a ratio. The equation for it is

dV = I_sp * G * ln(starting mass / ending mass)

where G is Kerbin (Earth) gravity, and the starting and ending masses are for a specific stage.

This means that if you double the amount of everything on your rocket, you still have the same ratio, and so, the same delta-v. However, you get more delta-v if you copy more fuel and less of everything else. Also, staging can help. Make sure to minimize extra mass (especially extra engines).

[Wallace]

you do have 2 horsepower so to speak, but as you have double the weight too, it means you end up with the same amount of work done.

Delta V is not a measure of power, it is more like how far the horse can go before it is tired out. so two horses going side by side will still only go as far as one horse on it's own. however if you attach some payloads to those tugs, your double one should be able to take the same load further.

[Tank Buddy]

Your delta V does not change, you tripled your mass if you had 3 connected, so if anything it would go down.

[joe indian]

Thanx.

Joe.

[Luis]

However, if you connect your tugs together and shut down all but one of the engines, you will end up with more delta V. Not a simple product of the number of tugs, because you still need to haul extra mass, but a little bit more. As you add more tugs, each one adds a smaller amount of extra dV until you reach a limit for that design.

[kurja]

However, if you connect your tugs together and shut down all but one of the engines, you will end up with more delta V. Not a simple product of the number of tugs, because you still need to haul extra mass, but a little bit more. As you add more tugs, each one adds a smaller amount of extra dV until you reach a limit for that design.

I don't understand how this would be possible, please elaborate? By my understanding the delta V does not change. Consider three identical engines drawing from a common fuel source, you get the same thrust and efficiency from each of them, delta V should be the same regardless of how many of them are used at any time.

[kurja]

Thanx.

Joe.

But, if you're using them to tow something, then you'll have more delta V with two tugs than with just one. As said delta V is the same if it's just the tugs.

[Awaras]

However, if you connect your tugs together and shut down all but one of the engines, you will end up with more delta V. Not a simple product of the number of tugs, because you still need to haul extra mass, but a little bit more. As you add more tugs, each one adds a smaller amount of extra dV until you reach a limit for that design.

This is not correct.

The only way he can increase dV by shutting down engines is if he has a mix of engines with different Isp's and he shuts down all less efficient engines. If he only has one engine type, than the dV will remain the same no matter how many engines he shuts down.

Now, if he was to REMOVE all those extra engines completely, he would get an increase in dV because of the mass reduction (with the tradeoff of a longer burn time).

[SRV Ron]

DV is a function of the amount of mass to be accelerated VS the amount of fuel consumed plus the efficiency of the engine. Also, the mass being accelerated will drop as fuel is used.

Two tugs will go a given distance when they both fire their engines until they run out of fuel. Stage one on top of the other, fire the first stage tug that now pushes the second stage one, dump it when it is out of fuel and fire up the second tug until it runs out of fuel, and you will send that tug a lot further out. The reason that will work is because you have eliminated the mass of the empty tug. IE, a smaller mass will be sent out to a much further distance then a bigger one given a starting mass of fuel and engine efficiency.

Now, two tugs pushing a given mass will send it further then just one tug. But because their mass has to be included in the Delta V, two tugs will not double the distance the payload mass will be sent. That payload will be sent further if you stage the tugs, use one to push the second and the payload, then dump it and its dead weight mass when it runs out of fuel. That could double the distance sent based upon the mass of the two tugs.

How far it goes is a function of engine efficiency, the amount of fuel used, and the change in mass of the total package from start of the burn until all fuel is used up., and or, empty tanks dropped, engines no longer used jettisoned.

Lots of people use clusters of LV-1 not considering that you are pushing a mass of 2.25 tons per engine. Signally, they can push a payload a long distance on a 1000 units of fuel, but a cluster of LV-909s in place of the same cluster of LV-N can easily send the same payload much further on that same amount of fuel. Why, the additional mass is going to cancel out the higher efficiency of the LV-N.

If you are confused by the math, just experiment and see what works. That is the beauty of a sandbox program.

Edited September 6, 2013 by SRV Ron

[Javster]

If you add a module with little fuel and high mass, you won't get as far; like if you added a very heavy fuel tank to a car.