I built a probe...

[Chel]

For my career playthrough, I built a small rocket to explore Kerbin. It would travel on a suborbital trajectory, and after reaching the target biome, release the scientific payload (a materials bay, mystery goo, thermometer), and land, to be recovered for science. On it's first mission, I managed to get all the way to Kerbin's north ice caps. on the second, I tried to get it to the big desert (not that far away from the KSC). Instead, I ended up in the highlands for some reason. I've been trying to reach the desert, but seem to fail. So, should I

A) Add more fuel

B) Reach a higher altitude to then cover more distance

C) Cheat and put 'Infinite Fuel' on.

I was able to reach the ice caps, but can't reach the desert (which is closer to the KSC). Does anyone know why?

[Starman4308]

In theory, it could be that you're trying to go retrograde and getting hit by the loss of rotation from KSC.

In practice, I suspect you were just first time lucky with the ascent profile, hitting it dead-on while not quite managing it the second time around.

 

There are a few things you can try:

Refine your gravity turn: try turning more or less steeply until you have a good handle on what maximizes distance.

Add more delta-V: once you can hit orbit, you can hit any biome fairly easily on the deorbit.

Add some aerodynamic control surfaces to glide to the target, instead of a purely ballistic trajectory.

[Chel]

12 minutes ago, Starman4308 said:

In theory, it could be that you're trying to go retrograde and getting hit by the loss of rotation from KSC.

In practice, I suspect you were just first time lucky with the ascent profile, hitting it dead-on while not quite managing it the second time around.

 

There are a few things you can try:

Refine your gravity turn: try turning more or less steeply until you have a good handle on what maximizes distance.

Add more delta-V: once you can hit orbit, you can hit any biome fairly easily on the deorbit.

Add some aerodynamic control surfaces to glide to the target, instead of a purely ballistic trajectory.

I don't go into orbit, I just go up out of the atmosphere, and come back down again. I could try adding wings, and making it a rocket-plane hybrid. At the moment, I only have access to the mk1 cockpit and the smallest elevon (roughly about tech tree node level 3 or something)

[Starman4308]

4 minutes ago, The_Cat_In_Space said:

I don't go into orbit, I just go up out of the atmosphere, and come back down again. I could try adding wings, and making it a rocket-plane hybrid. At the moment, I only have access to the mk1 cockpit and the smallest elevon (roughly about tech tree node level 3 or something)

Regardless of whether you're going suborbital or fully orbital, you still want to make a gravity turn to minimize aerodynamic and gravity losses, turning slightly towards your destination soon after launch and just following your prograde marker. For suborbital trips, you probably want a relatively steep profile, meaning a small, relatively late gravity turn, giving you a fairly high arc.

While in practice you're probably going to need to make at least small corrections, ideally from launch to burnout is one smooth arc placing you where you want to go.

[Kryxal]

Given the range and size of the target, I'd go with a fairly standard gravity turn, though starting out west can change that some.

[Guest]

9 hours ago, The_Cat_In_Space said:

I don't go into orbit, I just go up out of the atmosphere, and come back down again. I could try adding wings, and making it a rocket-plane hybrid. At the moment, I only have access to the mk1 cockpit and the smallest elevon (roughly about tech tree node level 3 or something)

Rocket planes work, even at that very low tech level. The Reliant is a very good choice of engine for them. They can also be easier to fly "right" than rockets -- basically, point them at the sky at about 45 degrees, then follow prograde once you hit 10 km or 500 m/s.

That was the good news.

The bad news is that they're not more efficient than rockets. You win a little by getting away with a lower thrust to weight ratio (i.e., you can pack more fuel), but you lose a little by having to pack wings, landing gear, and aerodynamic surfaces, and (usually) staying in the atmosphere longer.

In other words, I don't think you'd find it any easier to get where you want to go with a rocket plane than a plain rocket (if you pardon the pun). 

So, in addition with what the others said -- refine your gravity turn -- you need to do what everybody needs to do: find a way to pack more delta-V on your craft. That means either (1) make the payload smaller, (2) use a more efficient engine, or (3) make it bigger. Since this is mostly an atmospheric craft, you should also see if you can make it more slippery (better aerodynamics).