[TUTORIAL] Making a flying armor 2022.x - Forge 1.18.2 - Look at the comments for updates up to 2023.x 1.20.1

Thanks.

Thanks.

The code slightly changed ... the following goes before the last "}" in the code. 

For MCreator EAP 2022.3 b41417 ONLY

   @Override
   public boolean canElytraFly(ItemStack stack, net.minecraft.world.entity.LivingEntity entity) {
      return true;
   }

   @Override
   public boolean elytraFlightTick(ItemStack stack, net.minecraft.world.entity.LivingEntity entity, int flightTicks) {
      if (!entity.level.isClientSide) {
         int nextFlightTick = flightTicks + 1;
         if (nextFlightTick % 10 == 0) {
            if (nextFlightTick % 20 == 0) {
            //=============SPECIAL NOTE================
            
// If needed set stack.hurtAndBreak from 1 (default value - breakable) to 0 (unbreakable)
            
//=============SPECIAL NOTE================
               stack.hurtAndBreak(1, entity, e -> e.broadcastBreakEvent(net.minecraft.world.entity.EquipmentSlot.CHEST));
            }
         }
      }
      return true;
   }

@Zavgar4

Never tried it, but it basically will require a YourCustomRocketEntity and YourCustomRocketItem classes extending FireworkRocketEntity and FireworkRocketItem classes.

Once created go inside YourCustomRocketItem (which needs to look for the entity), now you need to add the following lines pointing to your custom rocket which Overrides the default rocket.  

   /**
    * Called to trigger the item's "innate" right click behavior. 
    * What to change?
    * Change FireworkRocketEntity to your YourCustomRocketEntity
    */
   public InteractionResultHolder<ItemStack> use(Level pLevel, Player pPlayer, InteractionHand pHand) {
   			// IF PLAYER IS FALL FLYING-ELYTRA FLYING
      if (pPlayer.isFallFlying()) {
         ItemStack itemstack = pPlayer.getItemInHand(pHand);
         if (!pLevel.isClientSide) {
         	// HOLDING FIREWORK ROCKET OR CUSTOM ROCKET
            FireworkRocketEntity fireworkrocketentity = new FireworkRocketEntity(pLevel, itemstack, pPlayer);
            pLevel.addFreshEntity(fireworkrocketentity);
            if (!pPlayer.getAbilities().instabuild) {
               itemstack.shrink(1);
            }

            pPlayer.awardStat(Stats.ITEM_USED.get(this));
         }

         return InteractionResultHolder.sidedSuccess(pPlayer.getItemInHand(pHand), pLevel.isClientSide());
      } else {
         return InteractionResultHolder.pass(pPlayer.getItemInHand(pHand));
      }
   }

And inside the YourCustomRocketEntity 

/**
 * Called to update the entity's position/logic.
 */
public void tick() {
   super.tick();
   if (this.isAttachedToEntity()) {
      if (this.attachedToEntity == null) {
         this.entityData.get(DATA_ATTACHED_TO_TARGET).ifPresent((p_37067_) -> {
            Entity entity = this.level.getEntity(p_37067_);
            if (entity instanceof LivingEntity) {
               this.attachedToEntity = (LivingEntity)entity;
            }

         });
      }

      if (this.attachedToEntity != null) {
         Vec3 vec3;
         if (this.attachedToEntity.isFallFlying()) {
            Vec3 vec31 = this.attachedToEntity.getLookAngle();
            double d0 = 1.5D;
            double d1 = 0.1D;
            Vec3 vec32 = this.attachedToEntity.getDeltaMovement();
            this.attachedToEntity.setDeltaMovement(vec32.add(vec31.x * 0.1D + (vec31.x * 1.5D - vec32.x) * 0.5D, vec31.y * 0.1D + (vec31.y * 1.5D - vec32.y) * 0.5D, vec31.z * 0.1D + (vec31.z * 1.5D - vec32.z) * 0.5D));
            vec3 = this.attachedToEntity.getHandHoldingItemAngle(Items.FIREWORK_ROCKET);
         } else {
            vec3 = Vec3.ZERO;
         }

         this.setPos(this.attachedToEntity.getX() + vec3.x, this.attachedToEntity.getY() + vec3.y, this.attachedToEntity.getZ() + vec3.z);
         this.setDeltaMovement(this.attachedToEntity.getDeltaMovement());
      }
   } else {
      if (!this.isShotAtAngle()) {
         double d2 = this.horizontalCollision ? 1.0D : 1.15D;
         this.setDeltaMovement(this.getDeltaMovement().multiply(d2, 1.0D, d2).add(0.0D, 0.04D, 0.0D));
      }

      Vec3 vec33 = this.getDeltaMovement();
      this.move(MoverType.SELF, vec33);
      this.setDeltaMovement(vec33);
   }

   HitResult hitresult = ProjectileUtil.getHitResult(this, this::canHitEntity);
   if (!this.noPhysics) {
      this.onHit(hitresult);
      this.hasImpulse = true;
   }

   this.updateRotation();
   if (this.life == 0 && !this.isSilent()) {
      this.level.playSound((Player)null, this.getX(), this.getY(), this.getZ(), SoundEvents.FIREWORK_ROCKET_LAUNCH, SoundSource.AMBIENT, 3.0F, 1.0F);
   }

   ++this.life;
   if (this.level.isClientSide && this.life % 2 < 2) {
      this.level.addParticle(ParticleTypes.FIREWORK, this.getX(), this.getY(), this.getZ(), this.random.nextGaussian() * 0.05D, -this.getDeltaMovement().y * 0.5D, this.random.nextGaussian() * 0.05D);
   }

   if (!this.level.isClientSide && this.life > this.lifetime) {
      this.explode();
   }

}

The code requires a lot more, but these parts are needed for the fall flying/elytra flying. I am using IntelliJ to modify the code. It is possible, but complicated.