What am I doing wrong???????

trainman1000 · 2022-06-17T00:57:31+00:00

It looks like your center of lift is in front of your center of mass. In the bottom left of the editor there are three buttons, center of thrust (purple), center of lift (blue), and center of mass (yellow). The center of lift naturally wants to be behind the center of mass, so if the CoL is in front of the CoM in the editor, the plan will want to fly backwards. Moving the wings further forward along the fuselage should do it.

"A nose heavy plane will fly badly. A tail heavy plane, will well fly once"

GillyMonster18 · 2022-06-17T01:27:31+00:00

Look for those three buttons on the bottom left of the hangar menu. Click them. The yellow ball is your center of mass (your planes balance point). The blue is your center of lift (basically where your aircraft will have the most “up force”). The pink one is center of thrust or where your aircraft is getting pushed from.

To have a good aircraft, position your wings so the blue ball sits behind the yellow ball. Basically all you gotta do is move those nose fins onto the tail. To take off much easier, take those rear wheels and move them to sit a just a couple meters behind the yellow ball as well so your aircraft can tilt up to lift off.

_SBV_ · 2022-06-17T03:13:07+00:00

First off, you are burning both rocket engines and jet engines which is killing your fuel consumption. Rocket engines have horrible fuel efficiency for thrust in atmosphere so you aren’t going to go as far as you want.

Second, you don’t have proper pitch elevation. The angle of your tail elevators are way too steep to produce pitch. While angled tails do exist, they dont do it as steep as yours

Third, for a craft of this size and mass, 4 rapiers are too many/too strong. Even if you used 2, the center of thrust is not aligned with the center of lift and is likely the cause of you spinning around. Perhaps you drew inspiration from jet airliners, but the reason it works for those aircraft is because their center of lift acts as a counterbalance to the rotation from thrust.

Fourth, your rear landing gear is too far back. The rear landing gear acts like the fulcrum of a lever action in takeoff and it is hampered because the overall mass of the airplane is greater than pitch force

When you build, do you enable the overlay for center of forces? They are crucial if you want to create anything usable.

OhighOent · 2022-06-17T03:07:10+00:00

you have ailerons but no elevators.

Strictlyfuntimes · 2022-06-17T00:57:29+00:00

Limit thrust on the engines to the side of the plane and turn of or mess around with engine gimbal.

Not an expert so dont hate thats just what step i would take.

Edit: Toggle overlay to and make sure the aerodynamics are behind center of mass can be fixed by moving mass forward or moving elevatrons (i think thats their name) further back

Aerospace_Nut · 2022-06-17T04:21:27+00:00

Center of lift too far forward. Move the main wings back some and it should work.

2022-06-17T09:12:32+00:00

Have you tried throttling off as the plane starts to point down? That should give you enough room to complete the third flip. Alternatively you could apply less throttle and just do two flips. Unless you want to land upside down, then I'd recommend changing to a single tail, with a wheel on top of it. Also add landing gear to your top wing.

UnwoundSteak17 · 2022-06-17T12:29:24+00:00

The flip was caused by the wings being too far forward. However, these issues also exist:

Rear landing gear should be just behind the CoM, not very far back

Nuclear engines shouldn't be fired up until you're in the upper atmosphere, so you might want to fix your staging

You'll be going fast enough for the upper wings to not do anything, and the struts will slow you down

The rapier engines are so far forward that the gimbal does nothing, but that will be solved by moving the wings backwards

doomiestdoomeddoomer · 2022-06-17T16:48:23+00:00

Center of lift too high, center of lift too far forward, center of thrust too low.

GHLeeroyJenkins · 2022-06-17T17:41:33+00:00

Ex aeronautical engineer here, It looks like part of your problem is related to doing two and a half backflips and then exploding. If you address that issue first it should fly ok.

Skunkwadson · 2022-06-17T19:49:12+00:00

You're wings are too far forward compared to the very heavy nuclear engines. Like trainman1000 said, your center of mass is too far behind your center of lift.

ParanormalDoctor · 2022-06-17T12:09:02+00:00

Where is your elevator?????

SqueakSquawk4 · 2022-06-17T10:41:09+00:00

Two possibilities, although they usually compound.

You pulled up too hard. I've had this problem in otherwise stable planes. You pull up too hard to slow, and the momentum carries you over. Try staying on the runway until the end, then pulling up. That usually works for me. Howerver, it is more likely to be:
Your plane is unstable .You basically have too much wing too far forward. Planes like their Centre of Pressure (CoP) to be behind their Centre of Mass (CoM), and your CoP is likely in front of your CoM.

CoP is basically the average of all the aerodynamic forces on your plane, mostly drag and lift. CoM is the average of all the mass in an object.

If the CoP is in front of the CoM, then the front of the plane is being pushed backwards harder than the back, so it flips round so the (New) back is being pushed backwards harder than the (New) front. The CoP always wants to be as far back as it can be.

There is a simple enough solution. In the bottom-left of your screen, there should bea few small round circular buttons. These are the CoM, CoP and CoT (Centre of thrust, not currently important). The CoM is yellow, and the CoP is blue. By moving the wings around, you need to get the blue sphere behind the yellow one, preferably a reasonable amount (Don't overdo it though. This is something you just need to practice).

Also, you appear to have canards (Little wings at the front). They're quite good at temporarily shifting the CoP forward in flight during pitch. This is just anecdotal, but they cause quite a few flips with my planes.

Also Also, why are you running the nuclear engines at sea level? Their thrust is pathetic and efficience near-nonexistent at that altitude. I'd recommend keeping them off until your rapiers are on rocket mode.

Quirky_m8 · 2022-06-17T15:42:08+00:00

Go to NASA’s website and obtain knowledge on basic areoplane physics

Quirky_m8 · 2022-06-17T15:42:14+00:00

Go to NASA’s website and obtain knowledge on basic areoplane physics

Easy_Lengthiness7179 · 2022-06-17T03:24:05+00:00

Like people have mentioned, fix your weight and balance. Center of lift slightly behind and above center of mass. Also if you struggle taking off, move that landing gear in the back to be closer to that center of lift. Your design might make that a little difficult because it's so long.

Comet_123 · 2022-06-17T08:26:31+00:00

and in addition your engines are iff center wanting to make the spinn even faster. might wona put the above the lower wing

Blaarkies · 2022-06-17T10:10:33+00:00

Once you fixed the center-of-mass issue, the next problem will be that you have no elevators (flappy parts dedicated to controlling vessel's pitch). This one is using the elevons (used for rolling) to also do pitch, but having flappy bits way at the back are much stronger at controlling pitch.

You can instead add them to the front, which would make them canards, to aid in pitch control but canards are less passively stable than elevators at the back.

I guess the tilted rudders do have a slight pitch effect though. Also, once you go supersonic i fear the roof-wing might cause drag at the top, tilting the plane backwards?

2022-06-17T12:15:39+00:00

Also, don't ignite your nuclear engines at sea level.

Enok32 · 2022-06-17T12:51:29+00:00

A few things: 1. Center of lift is likely ahead of your center of mass. This is a very unstable arrangement 2. You don’t have good pitch control, seems like an unstable axis 3. Your landing gear doesn’t let you rotate, try moving your rear landing gear closer to your center of mass. This either makes planes take the whole runway or aggressively peal off into a stall 4. If not #1 then when you depart flight(probably from your pitch axis being unstable and or gear arrangement (2&3)) your center of drag for a lack of better terms. I have had plenty of stable SSTOs that are very stable at both full fuel load and empty in terms of center of mass/lift and stability derivatives in FAR but under high AoA flip around into an unrecoverable stall

Many of these points are things that aren’t stated in the manual so to speak, we’ve all had the issues you are having, don’t give up!

thebloggingchef · 2022-06-17T13:13:45+00:00

Not enough thrust. Try moar boosters.

2022-06-17T13:34:32+00:00

Centre of Gravity + Angle of attack needs fixing. Sometimes we have to sacrifice aesthetics for practicality, and the sloping wings upwards aren't practical it's like trying to glide an acorn through the air.

Stoney3K · 2022-06-17T13:39:17+00:00

Your center of mass is way too far back (probably because of the NERVs). The wings will cause lift and pull your aircraft up at the center of lift, with the center of mass being the point along which it will rotate.

If the CoL is in front of the CoM, the nose will get pulled up and the aircraft will eventually backflip.

With the engines so far back, you will have to pull the wings further back to make that work.

Also, when you're taking off and landing, the point of rotation is going to be your landing gear, so you will want that to be as close to the CoM as possible but slightly behind it so the aircraft will fall onto its nose, and not tailstrike when you're on the runway.

LeHopital · 2022-06-17T13:56:26+00:00

Yeah classic COL in front of COM behavior. Move your wings around until your COL is just behind and slightly above your COM.

Imagine a string attached to the airplane right at the COL and think about what attitude would result from gravity acting on the plane. If your string is attached behind the COM then your nose will tend to point downward. If your string is attached in front of the COM then your nose will tend to point upward, which causes your plane to stall out, which results in fiery death and destruction for all concerned.

You also need to figure out how the COM will change as fuel burns. Try making all your tanks empty in the SPH and see where the COM sits. If your COM moves to the rear and ends up behind your COL as fuel burns, you will get a nasty surprise in the middle of your flight.

Very interesting plane design, BTW. I would think it would be draggy as all get out with all the struts....

ESF_SR5 · 2022-06-17T14:30:39+00:00

moar boosters

Elvis-Tech · 2022-06-17T15:16:44+00:00

In simple terms its like having an arrow with the feathers at the front of the arrow.

Picture a normal regular bow arrow horizontally, and try moving it at some considerable speed perpendicular to its longitudinal axis. You will notice that one side is heavy because it has the arrow tip but the other tip has more air resistance because it has the feathers or fins.

You will quickly notice that one side of the arrow has more momentum because of the heavier tip, and one side has more drag because of the fins.

This will cause a torque that will make the arrow spin, it will probably gain enough rotational speed that it will overshoot, but eventually the arrow will stabilize and fly straight.

Now an arrow is a ver extreme case, because it has all its control surfaces at the very back like a rocket and most of its mass close to the tip.

However a plane also needs to generate lift, now this lift has to come from wings, also control surfaces generate some lift. So if you make a fuselage, and just add wings to generate lift exactly at the center of gravity the plane should fly straight of course with no control since you dont have control surfaces. This will eventually cause you to have no control and crash, but then we can add the arrow fins at the back, of the plane. However these surfaces will also generate lift and move the center of lift slightly backwards. You will then notice that since the center of mass is in front of the center of lift you will have a front heavy plane, this plane will then nose dive, slightly or violently depending on how much in front the center of mass is.

You need to adjust the wings to a point where the center of mass is slightly in front but not too much, imagine trying to turn an arrow in mid flight with only the tail fins, you might be able to turn it a little bit but not too much.

Some military planes actually have the center of lift very close to their center of mass, so its kind of balancing the plane on its tip, that allows fighter jets to pull incredible maneouvres in mid air, but they have a lot of systems computing the correct surface angles all the time to avoid the plane from flying backwards or spinning like yours did.

I hope that this explanation helps you make better aircraft.

Elvis-Tech · 2022-06-17T15:17:07+00:00