problem with spaceplane urgent

[imcute]

 

2 minutes ago, AeroGav said:

Two things worry me :

okay thank u but i decided to continue working on my mk1 thing

problem now is,with already wings 4 times more than needed,it does not take off

4 minutes ago, AeroGav said:

2.5m nose cone

seems like old pic.

the new version has a fuel tank adapter and a nose cone

[AeroGav]

15 minutes ago, imcute said:

aww man fairing keep decoupled by mech jeb

https://image-gallery.imcute-aaaa.repl.co

@James Kerman

@AeroGav

That design looks fairly promising.  Is that a 2.5m fairing though,  attached to a 1.25m fuselage piece with no size adapter ?  Will make drag there.    Also , it looks like you are using two wheesley and one nerv engine ?   I would maybe use 2 rapier and 1 nerv or 2 nerv and 1 whiplash

[imcute]

14 minutes ago, AeroGav said:

.  Is that a 2.5m fairing though,  attached to a 1.25m fuselage piece with no size adapter

no its a 1.875 fairing shielded by 1.25 fairing so no drag i think

14 minutes ago, AeroGav said:

2 nerv and 1 whiplash

no its 2 wheatley and a nerv

https://image-gallery.imcute-aaaa.repl.co

@AeroGav

Edited June 26, 2022 by imcute

[AeroGav]

1 minute ago, imcute said:

no its a 1.875 fairing shielded by 1.25 fairing so no drag i think

no its 2 wheatley and a nerv

That doesn't sound like a viable propulsion system for SSTO.

One NERV is only 60kn,  same as a Terrier.     Close cycle Rapier is 3 times as much power.

If you are not going to use oxidizer engine,  then you will need 2 nervs at least.  And lots of wing,  and low drag.

Wheesely engines have hardly any power above mach 1.  If you really want to cruise around at low altitude and low speed on LAthe without using much fuel,  use a  Panther.    Or just mount a Whiplash for SSTO and put a pair of little Junos on the wing tips for cruising around.

If you are using NERVs to get to orbit try to store as much of your LF as you can inside mk1 strakes,  rather than fuselage tanks.    They will help it fly in the upper atmosphere when the jet engines have stopped. 

[imcute]

1 hour ago, AeroGav said:

just mount a Whiplash for SSTO

 

1 hour ago, imcute said:

2 nerv and 1 whiplash

yes i used this advice

and the nervs'tail nodes are sealed by nose cones

it loses controll at 10000m and 300m/s

1 hour ago, AeroGav said:

mk1 strakes

wing strakes?or big s ones?

Edited June 26, 2022 by imcute

[AeroGav]

1 hour ago, imcute said:

 

yes i used this advice

and the nervs'tail nodes are sealed by nose cones

it loses controll at 10000m and 300m/s

wing strakes?or big s ones?

This is strange.  

Stability should not change with speed or altitude - if the amount of air hitting the plane gets more (because of speed) or less (because of altitude) the strength of the aerodynamic forces will change,  but not their position on the craft.  If the center of lift is behind the center of mass,  the craft will still want to point its nose prograde.

Is it anything to do with fuel burning off ?  "RCS Build Aid" shows a red ball in SPH / VAB so you can see what happen to centre of mass when fuel is used.

Or maybe its just drag from the fairing.  It is a very big one..   like i say the converter and ore tanks don't need to be inside, only the drill.

One other thing.. it's not to do with  Angle of Attack is it ?  I would have thought if this was your problem you would notice on takeoff already.

A plane that looks stable at low angle of attack but suddenly becomes unstable at high pitch is either bending in flight from G forces,  or you've got some aero surfaces angled up a bit at the rear of the air plane.   This gives the back end more lift and makes the blue arrow look like it is in right place in hangar, but when you pitch up,  the rear end stalls first.

I am also confused by your statement "too much wing to take off".    It should be easier to take off with more wing.

Strakes - yes Big S wing strakes weigh the same as other wing parts that make the same lift,  and have the same drag.   But they also store fuel,  which makes them over powered.

 

 

 

[imcute]

JuneDay!JuneDay!

my space plane is bad to controll on the yaw axis

so it always gets out of controll

i dont wanna make a kal overclock on it

[imcute]

17 minutes ago, AeroGav said:

Is it anything to do with fuel burning off

my jet engines are effecient

17 minutes ago, AeroGav said:

only the drill.

whoops  i would fix that tommorow(its nine thirty for me!!!)

17 minutes ago, AeroGav said:

more wing.

i mean,not "too much and it cant take off"

i mean that we only need a quarter of this wing set

18 minutes ago, AeroGav said:

Big S wing strakes

okay

18 minutes ago, AeroGav said:

Angle of Attack

no its always 10 to 20 degrees

19 minutes ago, AeroGav said:

angled up

 

19 minutes ago, AeroGav said:

bending

no

autostrut on and no wacky wing placement

i think that the problem appeared on liftoff but it was stable enough to not need adjustments.An adjustment by sas instantly makes it tumble on yaw axis causing it to tumble on other directions too

elevons are bad for yawing

[AeroGav]

7 hours ago, imcute said:

no its always 10 to 20 degrees

Just,  remember kids,    "Angle of Attack" and "Pitch" are not the same thing.

Angle of attack is the difference between where the nose is pointing, and where the plane is actually going (prograde marker in surface mode).

With a powerful engine like the Whiplash,  at times you will have a pitch of 10 - 20 degrees because of the steep climb rate.

But you never want your Angle of Attack to get much more than 5 degrees.

Above 5 degrees,  the lift to drag ratio gets worse, and you want to be trading at the best rate possible.

To fly well (not melt) in the upper atmosphere,  whilst keeping angle of attack at no more than 5 degrees, it is nice to have quite a lot of wing.

But the Whiplash engine thrust falls away very quick above 17km.     So you might be using much less than 5 degrees when flying on jet engine.   This is OK,  because the most important thing is to get as much speed out of the jet engine as possible. 

Once you are using NERVAs,   their thrust doesn't decrease with altitude,  but the ISP is much less than the jet's.   So the only thing that matters is to have the most efficient lift : drag ratio you can get. 

[Vanamonde]

Overlapping threads have been merged. 

[imcute]

3 hours ago, AeroGav said:

not the same thing

whoops i gave u what the navbol sez

thats pitch

1 hour ago, Vanamonde said:

merged. 

whoops i will try not to create

1 hour ago, Vanamonde said:

Overlapping threads

 

[imcute]

should i put a KAL ferry to every planet that has atmosphere to compensate the bad isp of atmos nervas?

On 6/25/2022 at 9:45 PM, king of nowhere said:

all I get is that you are trying some kind of spaceplane with vector engines and that it is somehow aerodinamically unstable. and instead of trying to make your plane stable, you are trying to fly it while unstable.

ur saying the opposite

Edited June 27, 2022 by imcute

[imcute]

11 hours ago, AeroGav said:

only the drill.

fixed

11 hours ago, AeroGav said:

- yes Big S wing strakes

fixed

photo gallerry:https://image-gallery.imcute-aaaa.repl.co

okay this time the plane works more easilly and lifts off quickly

[AeroGav]

16 hours ago, imcute said:

fixed

fixed

photo gallerry:https://image-gallery.imcute-aaaa.repl.co

okay this time the plane works more easilly and lifts off quickly

This is difficult because i think it is night time where i live when it is daytime where you live.

Now,

Major Issue

I can't believe  I didn't see this earlier.    Where are your vertical stabilizers ?   What is keeping you stable in yaw ?  When you mentioned losing control, I always assumed you mention in pitch, because that is the harder problem to solve.  I like to use big S wing strakes rotated vertical, and slide them to the back of the airplane.  maybe one on top of each outer engine pod.   But any tail fin is better than none !

Moderate Issue 

In your latest pic,  I see two extra Whiplash engines on the back of the NERVs.    I think this is a bad idea.    That is another four tons the NERVs will have to push to orbit, after the jets have stopped working.   I normally find you need twice as many nervs as jet engines.

Minor Issue.

In the last pic you added a pair of shuttle vertical stabilizers as tailplanes.   They are very large for a craft this size, but ok.   The main thing is they are not mounted as far back as they could be,  they are quite close to your centre of mass.   IF this is your only pitch control surface,  this means they have to generate a lot of downforce to get the tail down and the nose up,  and that downforce subtracts from the lift you are making.   If they are further from Centre of Mass,   they have more leverage and can get the same effect with less down force.

Minor Issue 2

The solar panels are still not in service bay.   I don't think you need such a big solar panel.   A smaller one might take longer on Laythe,  but it doesn't matter really because you will be in high time warp while making fuel.

RE:

BTW i still don't see any Big S wing parts on your plane or am i looking at an old pic ?

 

RE:  Using KAL intake exploit on NERVs  so they work better in atmosphere

I think you asked this earlier.   

I sometimes use NERVs on Kerbin above 7km to help me get through sound barrier, if levelling off from my climb is not enough.

Otherwise it's a waste of fuel ,  I don't put them on until i am at 17km, in level flight and the jet engines are not able to accelerate me any faster.  NERvs are a lot more fuel efficient than normal rockets but still terrible compared to jets.

On Laythe, same principle.

On Duna,  the atmosphere is so thin, the NERVAs work great even at surface.   Which is lucky because Jets don't work on Duna (no oxygen)

 

 

 

 

[imcute]

6 hours ago, AeroGav said:

no oxygen

makes me think of eve

can nervs work on eve(expecting a no)

if not how can i compensate(helicopter?)

6 hours ago, AeroGav said:

Where are your vertical stabilizers

whoops omitted that tail fin due to driving away my col

ill add them back

bc now i know that i do not need my nose cone col com all at one line,i only need to make my col slightly behind com and it does not matter if its up or down

6 hours ago, AeroGav said:

twice as many nervs as jet engines.

okay then i would triple the nervs too due to finding out that one wiplash can't get me anywhere

6 hours ago, AeroGav said:

only pitch control surface

no but i should remove them or take them far away from com

6 hours ago, AeroGav said:

The solar panels are still not in service bay

okay ill fix it

6 hours ago, AeroGav said:

old pic

yes the latest pic has a big s wing strake for roll controll and pitch controll which you mentioned:

6 hours ago, AeroGav said:

In the last pic you added a pair of shuttle vertical stabilizers

 

6 hours ago, AeroGav said:

Using KAL intake exploit on NERVs  so they work better in atmosphere

that is confusing me

nervs do not need intakes

you are either wanting to overclock the nervs(bad idea,bad isp)

or wanting to use underclocked intakes so jet engines work in space(unfortually does not work,the jet engines work just like in eve and does not get oxygen)

6 hours ago, AeroGav said:

I don't put them on until i am at 17km

yes i have 2 motion groups for them one is for closing the jets and opening the nervas and another is for opening the jets and closing the nervas

6 hours ago, AeroGav said:

On Duna,  the atmosphere is so thin, the NERVAs work great even at surface

okay but this advice does not work before i take my plane to orbit

6 hours ago, AeroGav said:

 I don't think you need such a big solar panel

i need to open my 30watt isru converter(lf only)

the other things would be powered by 8 plutonium orbs like the ones on new horizon

7 hours ago, AeroGav said:

This is difficult because i think it is night time where i live when it is daytime where you live.

unfortually yes

we have to bear the time zone problem

[imcute]

https://image-gallery.imcute-aaaa.repl.co

found out that there is too much nervae and we cant decrease the amount of whiplashes

[imcute]

could not launch nerv-enriched ssto

[Zacspace]

Is this your first SSTO?

Regardless, I think you'll have more success if you limit your scope for now. It looks to me like you're trying to make an SSTO than can refuel itself and fly anywhere, which is a pretty tall order. SSTAs, as the KSP community likes to call them, are pretty extreme designs generally. You'll need a detailed understanding of KSP's physics and aerodynamics (and especially where they deviate from real life) and a fair amount of experience to pull it off.

If you've never built an SSTO before, I'd suggest skipping the NERVs and the drills/converters and just trying to build a mk2 based plane that can fly to orbit and back with 1 or 2 rapiers and no other engines.

If you've been to orbit with an SSTO before, Try building one with a NERV on it and some extra liquid fuel, See if you can make it to Minmus.

Once you can make it that far, build an SSTO that can do it with some cargo, then maybe stick some small refueling gear in the cargo bay.

 

Edit: I had a look at your pictures. You keep attaching things to the end of your NERV engines. That will block them from producing thrust. They'll still show rocket exhaust, but all that will happen is your nosecones or whiplash engines will be heated up by them. If you want to occlude the rear attach node for better drag you have to offset whatever part you use out of the way after or decouple it before firing the engine.

Edited June 28, 2022 by Zacspace

[imcute]

8 minutes ago, Zacspace said:

Is this your first SSTO?

no but it is my first ssto that has to run on planes instead of kal powered vector engines

8 minutes ago, Zacspace said:

can fly to orbit and back with 1 or 2 rapiers and no other engines.

aww ok

 

[imcute]

k i will try to make a rapier ssto

5 hours ago, Zacspace said:

block them from producing thrust

aww okay

[imcute]

aww man my plane runs out of oxidizer rilly fast

https://image-gallery.imcute-aaaa.repl.co

a plane did not have any nervae,this is what happened to its orbit

so i launched the plane and keeped it at <5 degrees pitch

but then the wings went on fire and i had to get 20 degrees of pitch to lift higher to avoid the same thing thats causing fire cause drag

and then when the wings are no longer on fire,<5 degrees of aoa

and it worked fine

at 20000m,i had to switch to rocket mode and it worked even better

then oxidizer ran out and i get a suborbital trajectory with apoasis 248km(due to not looking at the map frequently enough)

[imcute]

pretty flat tho.the trajectory was nearly an orbit but it only got half a kerbin before getting back to ground

[James Kerman]

8 minutes ago, imcute said:

aww man my plane runs out of oxidizer rilly fast

It looks like you still have half the tanks filled with liquid fuel, if you remove some of that it will make the vessel lighter and easier to get to orbit. It looks like you are getting to orbital speed so I think you're nearly there. By the way, that's a great looking design! 

[imcute]

Just now, James Kerman said:

orbital speed

NO！

orbital speed is three times this speed(1000m/s)

1 minute ago, James Kerman said:

, if you remove some of that

okay

1/3 fuel removed(most from fat wings)

lemme test it out

[James Kerman]

Just now, imcute said:

NO！

Is this not in meters per second?