Squad Should Re-Balance the Poodle Engine

[King Arthur]

I've found many uses for the Poodle as orbiter and lander engines. Its efficiency rivals the LV-909 which I use for 1.25m orbiters/landers, and it's far more practical than spamming LV-Ns for similar purposes (also less radiation).

I almost never use the 48-7S outside of probes despite their overbearing efficiency and effectiveness. Why? Because 0.625m engines clustered on 1.25m and 2.5m rockets look arse-ugly; plus, the Poodle and LV-909 simply sound better than the 48-7S.

[Tweeker]

So it's a matter of TWR. Your payload may be too large for the Poodle, you may switch from larger engines to the Poodle too early, or your ascent path could requires a high TWR for circularization. Can you show an example of a rocket where you tried using the Poodle?

With a 10t payload, I put a poodle and a -16 fuel tank under it. This gives me a last stage of:

21T

1770 m/s delta V

Below this I put a -64 and a -32 Fuel Tank and a Mainsail, that gives me

Total

80 T

4884 m/s of Delta v

so:

1st stage

60 t

3112 m/s D/V

2ND stage

10 t

1772 M/S D/V

300 M/S Spare d/v

10 tones to LKO

2 points however:

A) I can swap in a LV-T30 with no, or little change and gain a small amount of Delta-v, using an LV-T45 I loose a small amount, but they are both lighter and cheaper than the Poodle.

Additionally as the payload gets heavier the Poodle falls behind in it's ability to deliver enough D/V quickly, time is more critical at this point than ISP, cost, or form. It is easier, to add lv-30s or -45s radially, or to switch to a Skipper.

The poodles real flaw is that there are 2 engine that easily replace it in it's intended role. The area right around 200 KN thrust is crowded, unlike the rest of the range. There are 3 engine within 10% of each other thrust wise, but you have to go up 300% to get to the next engine the Skipper. Increasing the Poodles thrust would take it out of this cluster, and give it a place to shine on it's own.

[Murph]

The poodles real flaw is that there are 2 engine that easily replace it in it's intended role. The area right around 200 KN thrust is crowded, unlike the rest of the range. There are 3 engine within 10% of each other thrust wise, but you have to go up 300% to get to the next engine the Skipper. Increasing the Poodles thrust would take it out of this cluster, and give it a place to shine on it's own.

There's only 1 engine which is low-profile for use on landers, and 2.5m, that's the Poodle. It doesn't need to be moved to shine, it already does that very nicely in its intended role on a 2.5m lander. It is not intended as an upper lifter stage engine, although can work ok there with a light payload and a suitable strong lower stage.

Frankly, you're using the Poodle for the wrong thing, not in the role it's designed for, your design is wrong. Alternatively, add a couple of boosters to your 1st stage, and your problem is solved. Alternatively, just use the Skipper if you want the dV delivered quickly, and your problem is solved. Lots of different solutions for you, none of which require taking the Poodle away and leaving us without a good 2.5m lander engine.

[LABHOUSE]

...The poodles real flaw is that there are 2 engine that easily replace it in it's intended role. The area right around 200 KN thrust is crowded, unlike the rest of the range. There are 3 engine within 10% of each other thrust wise, but you have to go up 300% to get to the next engine the Skipper. Increasing the Poodles thrust would take it out of this cluster, and give it a place to shine on it's own.

But it is a 2.5 version of the engines it replaces, it would look bad if you put a 1.25 engine on a larger fuel tank.

[John FX]

While we are talking about gaps in the engine spectrum,

Where are the 100Kn engines?

We have a few at around 200-250, a lot under 60 but none around 100?

Often I have wanted a 100kn engine to fit in a 1.25m stack with a relatively low profile, for landers.

Restricting a poodle just means carrying around a metric tickload of weight for no reason. I`d like it to fit with the design also so using two smaller engines is out.

If we can have a fairly efficient engine with a good TWR at 220 and 50, why not 100?

It`s something I`ve felt missing for a while now.

[Jouni]

A) I can swap in a LV-T30 with no, or little change and gain a small amount of Delta-v, using an LV-T45 I loose a small amount, but they are both lighter and cheaper than the Poodle.

The LV-T30 and the LV-T45 can be more efficient, because they are much more lightweight than the Poodle, and their Isp is essentially the same. They are 1.25 m engines, however, so they have weaker connection nodes than the Poodle, and the engine fairings are also wrong size. Hence a single LV-T30 or LV-T45 cannot replace the Poodle, unless you reinforce it with struts and don't care at all what the rocket looks like.

Additionally as the payload gets heavier the Poodle falls behind in it's ability to deliver enough D/V quickly, time is more critical at this point than ISP, cost, or form. It is easier, to add lv-30s or -45s radially, or to switch to a Skipper.

I've used the same upper stage as in your example for payloads up to 30 tonnes. With larger payloads, the burn time remains the same, while the delta-v decreases, so lower stages have to do a bit more work.

There's only 1 engine which is low-profile for use on landers, and 2.5m, that's the Poodle. It doesn't need to be moved to shine, it already does that very nicely in its intended role on a 2.5m lander. It is not intended as an upper lifter stage engine, although can work ok there with a light payload and a suitable strong lower stage.

I don't understand why people use the Poodle as a lander engine. It's not low-profile, and it's way too heavy for most landers. A single 48-7S engine with an X200-8 fuel tank can carry 5 tonnes of payload to the Mun and back, and if you add a second engine, you can land on Duna with 4 tonnes of payload.

[Tweeker]

The LV-T30 and the LV-T45 can be more efficient, because they are much more lightweight than the Poodle, and their Isp is essentially the same. They are 1.25 m engines, however, so they have weaker connection nodes than the Poodle, and the engine fairings are also wrong size. Hence a single LV-T30 or LV-T45 cannot replace the Poodle, unless you reinforce it with struts and don't care at all what the rocket looks like.

In the end function trumps form, When you build landers with " A single 48-7S engine with an X200-8 fuel tank" you are making a lot bigger step down than swapping a lv-t30 for a poodle, and Not worrrying about the mismatch between a 2.5m tank and a .625m engine.

I've used the same upper stage as in your example for payloads up to 30 tonnes. With larger payloads, the burn time remains the same, while the delta-v decreases, so lower stages have to do a bit more work.

For an upper stage burn time is the critical issue, with a 30t payload, with about 1080 fuel and 1162 D/V the Poodle has a burn time of 3 minutes 30 sec. to reach LKO you need to start circularizing at about 40,000 and 1:45 before apoapsis. If you swap in a Skipper your D/V drops by 84 m/s, but the rocket's TWR goes from .49 to 1.41 and you can start burning much later, about 33 sec before apoapsis. With no change to your rocket's form.

If you radial mount 2 lv-t30s you see similar improvement. D/V drops by 65, or 5%, but TWR of the rocket is .95 and the burn only takes 1min 45 sec. 3 lv-30s give you similar performance to the skipper.

The TWR of a poodle powered rocket doesn't go above 1.0 until the entire rocket is below about 26 tons. To keep the burn time reasonable, >2 minutes, you can't lift more than about 10 tonnes More than this and the poodle take too long to make the burn. If you lift the rocket higher you might as well circularize with your transfer engine.

[King Arthur]

I don't understand why people use the Poodle as a lander engine. It's not low-profile, and it's way too heavy for most landers.

If the Poodle is not low-profile then what do you call a Mainsail? Mega-profile? Either you're confusing the Poodle for another 2.5m engine or you don't understand what "low-profile" means.

A single 48-7S engine with an X200-8 fuel tank can carry 5 tonnes of payload to the Mun and back, and if you add a second engine, you can land on Duna with 4 tonnes of payload.

A 48-7S under a 2.5m tank also looks butt-ugly, some of us aren't number min-maxers and actually want to design and fly rockets that are aesthetically pleasing.

---

For an upper stage burn time is the critical issue, with a 30t payload, with about 1080 fuel and 1162 D/V the Poodle has a burn time of 3 minutes 30 sec. to reach LKO you need to start circularizing at about 40,000 and 1:45 before apoapsis. If you swap in a Skipper your D/V drops by 84 m/s, but the rocket's TWR goes from .49 to 1.41 and you can start burning much later, about 33 sec before apoapsis. With no change to your rocket's form.

If you radial mount 2 lv-t30s you see similar improvement. D/V drops by 65, or 5%, but TWR of the rocket is .95 and the burn only takes 1min 45 sec. 3 lv-30s give you similar performance to the skipper.

The TWR of a poodle powered rocket doesn't go above 1.0 until the entire rocket is below about 26 tons. To keep the burn time reasonable, >2 minutes, you can't lift more than about 10 tonnes More than this and the poodle take too long to make the burn. If you lift the rocket higher you might as well circularize with your transfer engine.

Perhaps you should fly a different ascent trajectory that gives you more horizontal velocity? The Poodle is a decent engine, the problem you're describing sounds (with all due respect) more like a problem with your flying and failure to adjust appropriately to the situation.

Edited November 27, 2014 by King Arthur

[Jouni]

In the end function trumps form, When you build landers with " A single 48-7S engine with an X200-8 fuel tank" you are making a lot bigger step down than swapping a lv-t30 for a poodle, and Not worrrying about the mismatch between a 2.5m tank and a .625m engine.

There is a difference between stuff that's behind payload fairings, and stuff that's exposed to the elements during the ascent. A Mun lander can use designs that wouldn't be reasonable in a launch vehicle, just as the Moon lander used designs that were not reasonable in a launch vehicle. Even with FAR & DRE (which should be stock), the aerodynamic simulation in KSP is very rudimentary, and hence it's up to the player to avoid silly stuff that the game doesn't notice.

For an upper stage burn time is the critical issue, with a 30t payload, with about 1080 fuel and 1162 D/V the Poodle has a burn time of 3 minutes 30 sec. to reach LKO you need to start circularizing at about 40,000 and 1:45 before apoapsis. If you swap in a Skipper your D/V drops by 84 m/s, but the rocket's TWR goes from .49 to 1.41 and you can start burning much later, about 33 sec before apoapsis. With no change to your rocket's form.

You make a mistake by adding so much more fuel to the upper stage. Of course the burn time increases to unreasonable figures, if you intentionally make it so.

The amount of fuel in a stage should depend on the engine, with the payload only having a minor effect. The burn time always remains pretty much the same, while the TWR and the delta-v vary. As long as the TWR and the delta-v stay above certain thresholds, you can keep using the same upper stage, adjusting the lower stage and the boosters instead. This way you use the engines for what they're good for, adapting the design to the realities you face. If you don't have an engine for a certain role in a certain thrust range, you change the design to work with what you have, instead of building a design that doesn't work with the engine you use in it.

When I still played mostly stock, I had a family of medium-lift launch vehicles based on the same core design. The upper stage had a Poodle with an X200-16 fuel tank, while the lower stage had a Skipper with an orange tank and an X200-16 fuel tank. The rocket also had two boosters, which changed with the payload. For a 10-tonne payload, I might use two Rockomax SRBs. For 15-tonnes, I would switch to bigger SRBs. For 20 tonnes, the boosters had a Skipper and an orange tank each, and the lower stage was throttled down to 80%. For 30 tonnes, the boosters used Mainsails with two orange tanks each.

Compare this to the Delta IV, where the lower stage is always the same, and the upper stage always uses the same engine, with burn time either 850 s or 1125 s. With just the lower stage and a small upper stage, the Delta IV can launch 8.51 tonnes to LEO or 4.44 tonnes to GTO. With two SRBs and a small upper stage, the payload capacity is increased to 12.00/6.39 tonnes. With two SRBs and a large upper stage (with large fairings), the payload capacity is 10.22/5.49 tonnes. With four SRBs and a large upper stage, the payload capacity is 12.82/7.30 tonnes. By using two additional lower stages as boosters and a large upper stage, the payload capacity increases to 25.98/14.22 tonnes.

If the Poodle is not low-profile then what do you call a Mainsail? Mega-profile? Either you're confusing the Poodle for another 2.5m engine or you don't understand what "low-profile" means.

The Poodle is so tall (only marginally shorter than the LV-T30) that there's always the risk of the engine hitting ground on high-gravity bodies. Using it also raises the center of mass of the lander too high, which is generally a bad idea. The Poodle is about as tall as the 2-kerbal lander can and taller than the X200-8 fuel tank, while being clearly lighter than either of them.

The main reason why I don't use the Poodle in landers is that it's almost always much more powerful than needed. The 15.2-16.4-tonne Apollo Lunar Module used a single 45 kN engine in the descent stage. The Poodle is around 5x more powerful than that, so it's suitable for Mun landers heavier than 50 tonnes.

A 48-7S under a 2.5m tank also looks butt-ugly, some of us aren't number min-maxers and actually want to design and fly rockets that are aesthetically pleasing.

It doesn't look too bad, as it's also a low-profile engine with similar dimensions as the LV-909 and the Poodle. A tall 1.25 m engine under a 2.5 fuel tank looks much worse.

Edited November 28, 2014 by Jouni

[King Arthur]

The Poodle is so tall (only marginally shorter than the LV-T30) that there's always the risk of the engine hitting ground on high-gravity bodies. Using it also raises the center of mass of the lander too high, which is generally a bad idea. The Poodle is about as tall as the 2-kerbal lander can and taller than the X200-8 fuel tank, while being clearly lighter than either of them.

You are failing to look at the whole picture. Yes the Poodle is about as tall as an LV-T30, but it's also twice as wide. Comparing the Mainsail to its other 2.5m engine counterparts, the Mainsail and the Skipper, the Poodle is very noticably shorter in height and thus a low-profile engine in exactly the same way the LV-909 is considered a low-profile engine compared to the LV-T30/T45 and LV-N 1.5m engines. If you are tail-striking during landing, you aren't placing your landing legs down far enough.

The main reason why I don't use the Poodle in landers is that it's almost always much more powerful than needed. The 15.2-16.4-tonne Apollo Lunar Module used a single 45 kN engine in the descent stage. The Poodle is around 5x more powerful than that, so it's suitable for Mun landers heavier than 50 tonnes.

I've personally found more use for the Poodle as the primary engine for my orbiters and some of my tugs thanks to its great thrust and efficiency, with it also seeing use in many of my landers because of its convenient form factor. If you don't need the entire 220kn of thrust that the Poodle provides then simply don't use it, tweak it down if you really have to. Just because it's there doesn't mean you have to use it.

[Tweeker]

You make a mistake by adding so much more fuel to the upper stage. Of course the burn time increases to unreasonable figures, if you intentionally make it so.

if I build a 3 stage rocket with a 10.9 ton payload, 81 tons total, total delta v 4637m/s and the smallest 2.5m fuel tank above a Poodle I end up with:

1st stage

Mainsail a, X200-64 fuel tank

42 tons,

Delta V 1759 m/s

TWR 1.87, 3.08 empty

1min 15 sec burn time.

2nd stage

Skipper, and a 200X-32 fuel tank,

1min 29 sec burn time.

6.9 tons,

Delta V 974 m/s

TWR 1.26, 162 empty

3rd stage

poodle, and a 200X-8 fuel tank,

21 tons,

Delta V 1905 m/s

TWR 1.69, 2.85 empty

1 minutes 9 sec burn time.

That's the smallest 2.5M fuel tank and the poodle in the last stage, In this rocket the poodle works, but if you remove it, and add the X200-8 to the 2nd stage the Total delta V increases to 4676 m/s, so once again the poodle falls short, even using less fuel as you suggest. More fuel makes the burn time too long, and less makes the poodle expendable. If you work at it you can make the poodle work, but it is quite simple to remove it, and end up with a better rocket.

[Tweeker]

You are failing to look at the whole picture. Yes the Poodle is about as tall as an LV-T30, but it's also twice as wide. Comparing the Mainsail to its other 2.5m engine counterparts, the Mainsail and the Skipper, the Poodle is very noticably shorter in height and thus a low-profile engine in exactly the same way the LV-909 is considered a low-profile engine compared to the LV-T30/T45 and LV-N 1.5m engines. If you are tail-striking during landing, you aren't placing your landing legs down far enough.

I'm with Jouni on this, the Poodle is too heavy to be a lander engine, and too tall. For landers it is best to use the 48-7S or the LV-909. If your lander is heavier mounting multilpes of these radially will give your lander a wide base, and lower the CG enhancing it's stability. 4 LV-909s will give similar performance to the Poodle with the added benefit that the CG is lower, and the lander is wider, and more stable.

[King Arthur]

That's a very basic stock lander that I whipped up in like 10 minutes. Plenty of clearance beneath the Poodle with the legs extended and I'm not even trying to place the legs as low as possible, so I call bull at this notion that the Poodle is too tall.

[Jouni]

You are failing to look at the whole picture. Yes the Poodle is about as tall as an LV-T30, but it's also twice as wide. Comparing the Mainsail to its other 2.5m engine counterparts, the Mainsail and the Skipper, the Poodle is very noticably shorter in height and thus a low-profile engine in exactly the same way the LV-909 is considered a low-profile engine compared to the LV-T30/T45 and LV-N 1.5m engines. If you are tail-striking during landing, you aren't placing your landing legs down far enough.

My point was that the Poodle isn't low-profile enough to be useful as a lander engine. You have to place the landing struts really low, which raises the center of mass and makes the lander less stable. With smaller engines, you can place the landing struts higher and have a more stable lander, while still having enough clearance for the engines.

I've personally found more use for the Poodle as the primary engine for my orbiters and some of my tugs thanks to its great thrust and efficiency, with it also seeing use in many of my landers because of its convenient form factor. If you don't need the entire 220kn of thrust that the Poodle provides then simply don't use it, tweak it down if you really have to. Just because it's there doesn't mean you have to use it.

Tweaking engine power down a bit is often useful. If you tweak it down a lot, you end up carrying a lot of useless engine mass. In the case of a Poodle as a lander engine, that engine mass still takes a very awkward shape. A half-Poodle would be more useful as a lander engine.

These days I don't use the Poodle that much anymore, because I'm playing with the 6.4x Kerbol System, and the payloads end up begin much larger and the delta-v requirements higher than in the stock game. I used it in the CSM of my Apollo-style Mun mission and for delivering the command module of my Tylo ship, but usually the upper stage engine is a KR-2L (or even a KR-2L boosted by a few Skippers).

That's a very basic stock lander that I whipped up in like 10 minutes. Plenty of clearance beneath the Poodle with the legs extended and I'm not even trying to place the legs as low as possible, so I call bull at this notion that the Poodle is too tall.

Here is the difference between a Poodle and a 48-7S in a Mun lander:

The lander with a Poodle is 2.1 tonnes heavier and has over 500 m/s less delta-v, while the difference in the centers of mass is almost the height of the fuel tank. If more payload is needed, the center of mass of the lander with a 48-7S can be lowered even more by attaching the additional payload to the fuel tank.

if I build a 3 stage rocket with a 10.9 ton payload, 81 tons total, total delta v 4637m/s and the smallest 2.5m fuel tank above a Poodle I end up with:

Now you built a three-stage rocket with very little fuel for the engines and a lot of useless engine mass. I was advocating a similar design strategy as many real rockets use these days. Start with a good two-stage rocket that can launch a small-to-medium payload to orbit. Then, by adding side boosters, you can easily adjust the rocket for launching several times the original payload.

For example, start with a simple Poodle/X200-16 + Skipper/Jumbo rocket that can lift around 7 tonnes to LKO. Add two large SRBs throttled down to 60%, and the payload capacity increases to around 13 tonnes. Use two additional Skipper/Jumbo combos as boosters, and throttle the lower stage down to 80%, and the payload capacity becomes 22 tonnes. These three rockets cover a large fraction of the interesting payloads in the stock solar game.

As a side note, I tried rebuilding my old stock lifters from 0.23.5. It turns out that the designs I described no longer work, because the Skipper is too efficient. The TWR of the lower stage doesn't get up fast enough, so the rocket can't sustain the climb rate after booster separation.

[Tweeker]

That's a very basic stock lander that I whipped up in like 10 minutes. Plenty of clearance beneath the Poodle with the legs extended and I'm not even trying to place the legs as low as possible, so I call bull at this notion that the Poodle is too tall.

I can't see everything you've got on that lander, but I can see some of the stats, If you swap the poodle for a 48-7S you can make the lander shorter, lighter, and still have the same delta V.

I think you have a docking port on top, so I assume that you can use a quad adapter, on the bottom. This gives you the same Delta/v and TWR in a shorter, lighter, lander. about 6T VS 11.2T

If you mount 2 or more fuel tanks radially you can make the lander even wider, and more stable. Doing this has the added bonus of allowing you to jettison expended fuel tanks, and the landing legs after you land. Meaning you have a better TWR and Delta v when returning. 4 LV-909 mounted in this way effectively replace the poodle and add several additional benefits.

The poodle can be serviceable as a lander engine, but the are better choices.

[King Arthur]

The poodle can be serviceable as a lander engine, but the are better choices.

I'm glad that we can at least agree on something despite our differing opinions on the matter, that the Poodle still is a legitimate choice among others for a lander. It's not the best engine for the job going strictly by numbers, but at least we can both agree the Poodle is a usable lander engine.

[Tweeker]

Now you built a three-stage rocket with very little fuel for the engines and a lot of useless engine mass. I was advocating a similar design strategy as many real rockets use these days. Start with a good two-stage rocket that can launch a small-to-medium payload to orbit. Then, by adding side boosters, you can easily adjust the rocket for launching several times the original payload

In the 30T example the burn time was too long, and you say use less fuel, So I built the 10T rocket with less fuel in the top stage, and you say it has too little fuel. My fix for this is to remove the Poodle, and 3rd stage entirely, riding to orbit on the Skipper. Which is identical to what you describe. :

I was advocating a similar design strategy as many real rockets use these days. Start with a good two-stage rocket that can launch a small-to-medium payload to orbit.

For example, start with a simple Poodle/X200-16 + Skipper/Jumbo rocket that can lift around 7 tonnes to LKO

If I build the Lifter you describe, the Poodle does work, but I can lift the same payload with 1.25m engines, and the rocket is lighter and cheaper. You can lift 10t with a 2 stage 1.25m rocket, that weighs about 61T vs the 80T example I cited. As the payload increases beyond 10T The 1.25M 2nd stage dips bellow 1.0 TWR, and the burn time increase beyond 3 minutes per stage. So you need to switch to 2.5 M parts to do your lifting. The poodle has lost effectiveness by this point and the Skipper steps in, as in the 10T rocket example I cited previously. For the Poodle to fill it's roll it needs to lift ~7 tons and it can easily be replaced by 1.25M engines in this role.

Edited November 28, 2014 by Tweeker

[Jouni]

In the 30T example the burn time was too long, and you say use less fuel, So I built the 10T rocket with less fuel in the top stage, and you say it has too little fuel. My fix for this is to remove the Poodle, and 3rd stage entirely, riding to orbit on the Skipper. Which is identical to what you describe. :

In a launch vehicle, the amount of fuel in a stage should depend mostly on the kind of the engine used. A Poodle-powered upper stage should have an X200-16 fuel tank, a Skipper should have 1-1.5 orange tanks depending on its role, and a Mainsail should burn 2-3 orange tanks. Using less fuel means that the rocket is carrying useless engine mass, while more fuel usually makes the TWR too low.

If I build the Lifter you describe, the Poodle does work, but I can lift the same payload with 1.25m engines, and the rocket is lighter and cheaper. You can lift 10t with a 2 stage 1.25m rocket, that weighs about 61T vs the 80T example I cited As the payload increases beyond 10T The 1.25M 2nd stage dips bellow 1.0 TWR, and the burn time increase beyond 3 minutes per stage.

Are you sure about that 61-tonne figure? Did you actually build and fly the rocket, as I did with my example rockets for 7/13/22-tonne payloads? The 1.25 m engines are inferior to the Skipper and the Poodle, and the payload fraction sounds more like what's achievable with asparagus staging than with two vertical stages.

[Steambirds]

Oh god... what have I created?!

[rkman]

I'm glad that we can at least agree on something despite our differing opinions on the matter, that the Poodle still is a legitimate choice among others for a lander. It's not the best engine for the job going strictly by numbers, but at least we can both agree the Poodle is a usable lander engine.

Any engine can be used for landing as long as it provides enough TWR. But for most bodies the Poodle is way overpowered as a landing engine (the Poodle on that lander has a TWR of 14 on the Mun).

In most cases it is more ligitemate to use a smaller, less massive and cheaper engine that gets you more delta-v than the Poodle.

The one reason left to use the Poodle on a lander is that it fits nicely in a 2.5m stack. But "it looks nice" should not be a reason for choosing an otherwise far sub-optimal part.

[J.Random]

But "it looks nice" should not be a reason for choosing an otherwise far sub-optimal part.

Says who?

10chars

[Murph]

The one reason left to use the Poodle on a lander is that it fits nicely in a 2.5m stack. But "it looks nice" should not be a reason for choosing an otherwise far sub-optimal part.

"It looks nice", combined with "it works well" are very valid reasons for choosing it. It's clearly a lander engine, and while overpowered for very small and minimalistic 2.5m landers, its power allows it to work nicely for larger landers as well. I don't care whether my landers are super-optimal, only that they work nicely and have a comfortable margin of excess dV and excess power (only just enough is bad design in my book, as this is KSP and not a NASA mission where min-maxing is actually important).

I still don't actually believe that there's a gap to be filled between Poodle and Skipper, but if people want something more powerful than the Poodle and less than the Skipper, that's what should be added, leaving the Poodle alone. There is no downside to adding a 4th Rockomax engine, if people really feel they need something in that gap, but there's a significant downside to basically removing the current Poodle, which is what seems to be being demanded here.

Campaign for a new 300-400kN Rockomax 2.5m engine instead, and you'll get far less objection.

[Tweeker]

I'm sorry, that should have been 71tons, I can do it with less, but It's easier to do it reliable with a little extra Delta/v. I had the Frist stage attached radially, but you can put it vertically using a quad stack adapter. There is no asparagus staging, or fuel lines.

The first stage is:

4X aerospike plus 810 fuel, or 2 Ft-L800 and 1 Ft-L200 each.

46.7T

Twr 1.0

Delta/v 2693

burn time 2 min 53 sec.

The second stage is:

1 LVT-30, plus 3 FT-L800s.

14.6T

Twr .9 *

Delta/v 2093*

burn time 3 min 19 sec.

By the time you light this stage the twr will have increased to .99 and the Delta/v will have climbed to 2400.

In a launch vehicle, the amount of fuel in a stage should depend mostly on the kind of the engine used. A Poodle-powered upper stage should have an X200-16 fuel tank

Sitting under a 10T payload this would have a TWR of 1.06, If you change to a LV-T30 it would have a TWR of .99, but with the LV-T30 you can add another 45 fuel, to end up at the same weight, with a little more Delta/v than the poodle, not to mention the cost savings.

[BrotatoSalad]

I think it's really good in mun/minmus transfer stages, especially in career. I use the big radial engine for landers because it's more convenient to mount multiple ones and decouple from a flat fuel tank base. The poodle as it is has some utility, but it could use a buff or two.

[rkman]

"It looks nice", combined with "it works well" are very valid reasons for choosing it.

I think "it works a lot better" is a very valid reasons for choosing another engine.

It's clearly a lander engine

You mean you are certain that Squad intends it to be used primarily as a lander engine?

It is just an engine that has high vacuum ISP and a correspondingly low twr. These engines shine for large delta-v expenditures such as orbital transfer because that's where they make a positive difference in efficiency, not so much in relatively short landing burns.

Generally the intention in rocketry is to use the best engine for the job.

If another engine than the Poodle does a better job for a particular landing, why use the Poodle? The fact that it can do a decent job for big landers is no reason to also use it for a small lander, it is not that much "clearly a lander engine".

I don't care whether my landers are super-optimal "far sub-optimal", only that they work nicely and have a comfortable margin of excess dV and excess power (only just enough is bad design in my book

7 times as much power, 5 times as much cost and 20 times as much mass as needed is excessive in my book.

I don't think that "i don't care about efficiency" is a particularly strong argument in relation to a game that is very much about science and technology.

I agree though that the issue is less about re-balancing and more about not having enough engine options (and/or no proper engine clustering support) to begin with.