TrevorC42303

Posts
10 
Joined

Last visited
Content Type
Profiles
Forums
Developer Articles
Posts posted by TrevorC42303


My TWR for my first stage, if I've done my math correctly, is about .99 or 1. This doesn't seem right

The one thumper is enough to get me up as far as TWR goes, but it does not have the dV. My total dV for this ship is 3,704, and I would like to be around 4,500 just to be safe.

18 ton launchpad mass.
3. Thumper
2. Reliant, 4 tons of fuel
1. Reliant, 2 tons of fuel
Pod

This is my ship info thus far, including my recent changes.
Stage 1: a single thumper
(need more thrust) 2 fleas with the thumper?
Stage 2: a relient with 2 T200 fuel tanks, and 1 T100
Stage 3: same as stage 2 but including the pod, 1 Mk16 parachute, 2 Mk2R radialmount parachutes, various science gadgets, heat sheild, and decoupler.

8 minutes ago, Snark said:
Why do you have any radiator panels on the ship? At all?
I laughed way too hard at this. I figured as much.
How do I calculate TWR

Granted I am new to this, I may have used too many radiator panels, but I don't think removing them will add too much dV. I might be wrong. My image url is not cooperating.

4 minutes ago, Snark said:
What does your ascent profile look like? What's the TWR of your rocket on the launch pad? When you reach 45 degrees from vertical, how high are you and how fast are you going?
Ascent profile matters quite a lot, in terms of dV efficiency. A suboptimal ascent can waste quite a lot of dV.
My ascent profile is dreadful, it is steep, I do try and take advantage of the gravity assist in that I tilt east, but I can never quite get my ship to tilt enough for a solid profile. Also, at this point I do not have nose cones, so my 2 'thumper rockets create a heavy amount of drag, possibly the reason for the lack of control. My image is being loaded, one moment.

This has helped tremendously, I recalculated after my realization (still using ATM ISP for this, ending up with 5,685 deltav. I figured it would most likely be a little more than that based on the idea still that I underestimated. I know that it should take around 4,550 dV to reach LKO but even with my calculations, i reach the correct height, but don't have the dV left to make the orbital burn.
11 minutes ago, Snark said:Aside from the fact that your math has gone off the rails because you're not using the whole rocket mass... it's also worth noting that you have a really wrong number for Isp on this one. SRBs' Isp is nowhere near 520. ASL Isp for a Thumper is 175, and for a Hammer is just 170. So the value of the three of them together would be between those two numbers (closer to the former than the latter, since that's where most of the thrust is).
Didn't think to figure this, my thought process was to add all thrust in the stage to get a total thrust.

I have had KSP for the PS4 a total of 4 days now, and it's complexity and intricacy exceeds what I prepared for. I am happy in this, but mortified as well. I have started a science save file, and have only researched 4 additional groups including: basic rocketry, engineering 101, general rocketry, and survivability.
With the new parts acquired from researching these groups I built a simple, 3 stage ship, and have decided to try to achieve LKO. To do so efficiently, I delved into the KSP wikis and forums to find the relevant information. I understand to a certain point the rocket equation, or the "*dudes name I can't spell*'s equation".
Anyways, I found the ISP of the rockets used in each stage, and I wasn't going for complete accuracy at first, using the ATM ISP for every equation done. Then, I found the total mass of each individual stage, as well as the dry mass of the stages by themselves. In order to do so I had to take the first to stages off, and measure the total and dry masses for the last stage, then add the second stage and subtract the total mass of both stages my the total mass of the last stage to get the total mass of the second stage. Then I proceeded to do so with the first stage attached as well. I found both total and dry this way for the first and second stages.
Now that I have the ISP, M_FULL, and M_EMPTY, I figured I could calculate and add the answers together to find my overall deltav, granted I SHOULD have more than I calculate based on the idea that my ISP for each equation will be the atmospheric ISP.
My work: (weights are rounded)
Stage 1 (final stage): pod, fuel tank, and 'reliant' thruster. 
Dv = 265 * 9.8 * In (4/3) = 747
Stage 2 (second stage): 2 fuel tanks and 'reliant' thruster. 
Dv = 265 * 9.8 * In (3.5/1.5) = 2,200
Stage 3 (first stage) 2 BACC thrusters, and 1 'hammer' thruster, with added radiator panels.
Dv = 520 * 9.8 * In (19.5/4.5) = 7,472
I am now realizing that each stage must also push the weight of the stages above them, meaning I must carry the mass of those stages into that equation, adding to the total and dry mass of the stage being figured. If this is not so and I have created a false solution, please let me know, thank you.
Could someone help with these multistage Deltav calculations?
in Gameplay Questions and Tutorials
Posted
I flew a few times, and I reach 300 m/s around 50 degrees east, this seems almost perfect as this is when my solid fuel cuts and I blow my fist stage, here I realized I needed find on the second stage because my stability is off and I spin out of control. Once I did this I was able to retain a 4550 degree ascent till my AP reached around 80km, I then cut my engine with just about a 3rd of my fuel left in the second stage. I set a maneuver nose for a prograde burn to circularize my orbit. I started the burn with my second stage and finished with about half my last stage, using the other half to create a aerobrake as it was too expensive to create an impact from the single burn, I burned till my AP reached about 40 km, then I waited to hit atmosphere, when I exited the atmosphere, I could've waited for the next aerobrake and saved all my fuel, I burned the last of my fuel, dropping my orbit into kerbin.
Thank you for your help, I appreciate it greatly.