Flying planes on Kerbin

[strider3]

First, I apologize for my previous rant elsewhere...I let my aggravation get the better of me but...no excuses...nobody deserved that.

First, here's my low science level plane:

I am having 2 issues:

1. I have a contract that requires flight on Kerbin above 19,200, at one point, and I can't seem to get to that altitude with this aircraft? I've even added 4 more Juno's but I still can't seem to get to that altitude.

2. Flight control. I have the various control surfaces set as follows:

      Vertical stabilizer (tail): Yaw only

      Horizontal stabilizer (tail): pitch and roll only.

      Wing elevons: pitch and roll only.

      Whenever I use a key, say the up pitch (S), the aircraft does not just pitch up but rolls and yaws? It's making it very difficult to control the aircraft as I approach my Contract destination as it doesn't seem to just do the one thing I'm asking it to but, instead, goes off in all directions?

What am I not "getting" here? 

[bewing]

For #1 -- it's extremely difficult to get above 16km with a pure jet design until you have panthers. To get those kinds of altitudes, I always use rocket assist.

Here's an example craft that I use at low tech levels for doing high altitude contracts:

http://www.virtualrealitytoursllc.com/pix/3_juno.craft

[AeroGav]

This would also do it - 

https://kerbalx.com/AeroGav/Juno-basic-ssto

If you go to the  wiki http://wiki.kerbalspaceprogram.com/wiki/Jet_engine ,  and click

[expand] next to                     " the velocity and atmosphere curves of the jet engines "

You will see how the Juno fades badly after mach 1.5 and 14km

[Gianni1122]

For #2

Your elevons/ailerons might not need "roll" set

Scott Manley explains some of this starting around the 8:50 mark in this video:

 

EDIT: As for a low science way to complete altitude contracts, I sometimes for example, do a crew report at 20,000 after reentry form a sub-orbital.

Edited December 6, 2016 by Gianni1122

[strider3]

17 hours ago, bewing said:

For #1 -- it's extremely difficult to get above 16km with a pure jet design until you have panthers. To get those kinds of altitudes, I always use rocket assist.

Here's an example craft that I use at low tech levels for doing high altitude contracts:

http://www.virtualrealitytoursllc.com/pix/3_juno.craft

HMmmm, the link just opens a page full of text, bewing.

[bewing]

10 minutes ago, Victor3 said:

HMmmm, the link just opens a page full of text, bewing.

Yep, craft files are just text files. Store it on your system in the SPH directory of your game, and launch it like any other plane.

Note: if you want to make multiple high altitude hops in that plane, you have to play games with shutting the oxidizer in the tanks on and off.

So -- fly along on full jet power at 9 to 10km altitude and (when you reach a waypoint) pull the nose up 30 degrees and light the rocket.

Edited December 6, 2016 by bewing

[AeroGav]

18 hours ago, Victor3 said:

First, I apologize for my previous rant elsewhere...I let my aggravation get the better of me but...no excuses...nobody deserved that.

First, here's my low science level plane:

 

2. Flight control. I have the various control surfaces set as follows:

      Vertical stabilizer (tail): Yaw only

      Horizontal stabilizer (tail): pitch and roll only.

      Wing elevons: pitch and roll only.

      Whenever I use a key, say the up pitch (S), the aircraft does not just pitch up but rolls and yaws? It's making it very difficult to control the aircraft as I approach my Contract destination as it doesn't seem to just do the one thing I'm asking it to but, instead, goes off in all directions?

What am I not "getting" here? 

This control issue would be easier to troubleshoot if you put the craft file somewhere we could download it.

_{However,  I am concerned about the tail cone you have on the back there.  It's the non angled type A  because the slanted B connector is on a different tech node, and i remember someone telling you to just angle the regular A type.  Assuming that's what you've done, you need to be aware that this part generates a fair bit of body lift so i'm not sure what effect angling it will have.}

Try making those wing elevons roll only, and  limiting their  authority to 50% or less. 

They are too close to CG to be able to control pitch effectively, only a short lever arm.

The thing about ailerons is that if their angle relative to oncoming airflow exceeds 30 degrees they stall just like a wing would, which can lead to control reversal. 

eg.  plane is pitched up 10 degrees.

you try to pick a wing up by pressing a roll control key. These elevons deflect to 30 degrees if their authority is set to 100%

Total AoA of elevon = 10 + 30 = 40 degrees = stalled.   It will have very high drag on the side you are trying to pick a wing up on, so it will yaw really badly towards the low wing.  It will also generate very little lift , so you won't actually get that wing up.

So, if you're planning on flying at high angle of attack,  you need to reduce the aileron authority to reduce the deflection angles on these surfaces so they dont stall.  You might need to fit more ailerons to still have enough roll control as a result.

And you may need more vertical stabilizer area to cope with the worse adverse yaw that comes from aileron use.

 

[strider3]

18 hours ago, AeroGav said:

If you go to the  wiki http://wiki.kerbalspaceprogram.com/wiki/Jet_engine ,  and click

[expand] next to                     " the velocity and atmosphere curves of the jet engines "

You will see how the Juno fades badly after mach 1.5 and 14km

Using the atmospheric temperature/pressure curves for Kerbin, how do you get the 14km number? I'm not sure what math is needed to convert the Kerbin atmosphere chart to altitude?

EDIT...never mind, found it!

Edited December 7, 2016 by strider3
found the answer