Is it possible for you to merge solid fuselage blocks into one model, as well as calculating drag less often? This would save a lot of processing power as drag calculations take up a considerable amount of power, and doing it less often would allow users to build better, higher-quality creations. It could be an option under quality settings. For example "drag calculation frequency" from once a second to 1/10 of a second. Also, the creation of a single model from solid fuselage blocks could save CPU power because they cannot change position, and wouldn't require any additional drag calculations after an initial one when loading into the level. I know that would take away crashes, but some people just like flying around, so it could be an option in the settings. It would allow more people to play, especially people with low-spec computers.

I think maybe more damage suppression systems such as turning off engines to put out fires, if you don't they blow up and fire suppression systems. Also could you please make it easier to make fun turrets and maybe a multiplayer (with a part limit to mobile) and you can add a cockpit that other players can control, and maybe player models and even custom items they could use and a possibility for a bit of an interior for your aircraft. And make crashes a bit more realistic (like crunches, bits being torn off, and trees falling that you hit) and also custom cockpits for your player model and they can actually exit and enter the plane, maybe a new location such as a abandoned airport/runway. And more things to crash into such as buildings, trees, and more. I think that would be cool

I'm sorry to take up some of your time. I'll try my best to make the suggestions easy to understand. If there is any tone problem, please forgive me.
Some version updates are recommended for 2.0
Now that it's time to update 2.0, why not make a big update?
Part damage
Now that the cannon has been added, the game has a richer playing method, but the powerful weapons and fragile works seem to be a little inconsistent, so I suggest adding a "collision and explosion damage coefficient (1)" to all parts to make the parts stronger (0) or more fragile (+ ∞), so that the players can make stronger works to increase the fun of the war.Or simply add options that will not affect other parts after the parts are destroyed.
Visual enjoyment
At present, the effect of cannon seems to be a little unsatisfactory. I think it will look good to increase the smoke of cannon. If the effect of weapon explosion in water is water column, it will be better. In addition, can underwater camera mod be considered?
weapons
I suggest removing weapons such as bombs and missiles that will disappear in deep water, adding the option of hiding the somke tail to missiles or rockets, and adding the option of exploding when bombs fall into the water after being launched.
AI
Can you add some new sea targets? For example, World War II large aircraft carrier, transport ship. Plus, USS beast is twice as big and the destroyer is smaller than real size.
Parts
Like adding an engine that doesn't need air and works underwater?
Thank you for taking the time out of your busy schedule to read. I hope you can consider some of my suggestions.

Simple Planes is a great game, however it's accuracy in game physics and fluid dynamics isn't the best. Shippy456 states, "Due to my knowledge of very basic physics and fluid dynamics, I have become somewhat concerned about Simple Plane's physics and and it's drag model." WNP78 also describes, "Simple Plane's physics are definitely not as realistic as can be. They are pre-computed for each part at the start of the game and not updated if the craft's structure is changed. Parts which have no drag, when moved into airflow, will continue to have no drag. SimpleRockets2's drag model is more real-time, but at the end of the day, with all these things, it's about striking a reasonable balance between realism and not lagging out everyone's device." As you can see from these statements, I'm not the only one who is complaining about Simple Plane's current drag model. So, let's fix this! If you want an update on Simple Plane's physics, let's start voting! Thank you for your support!

Before anything Else, Please watch this Video:

https://www.youtube.com/watch?v=UL5z38ttArY

I have been developing and improving a Concept in Simple Planes. I Call it "The Strange Real Concept" or S.R.C. Its Main Relevance is:
Currently, Simple Planes Modern Dogfighting is Very Boring because one Missile can Kill you right away. And as you can See, the Concept is Very Fun but at the Same Time, It is VERY UNRELIABLE because the Missile Sometimes does not hit the Target Close enough to do Damage.

Reason why this should be placed In Game:

Realism Reason:
There is a Confirmed Footage of a Helicopter Surviving a Missile hit.
Footage:
https://www.youtube.com/watch?v=c1IEAt1SjhY

In Game Reason:
The Players are now starting to loose interest in the game. Yes, the Funky Trees saved it, But of course, not many people can understand how it works. And if people can't understand Funky Trees, then this May give them a reason to play; Make a Plane, and shoot down other planes in the community and give the player a Sense of "Multiplayer" .

Look, I know making Blast Radius is Hard. especially in a Game that involves more than 1 Parts. So I Suggest instead of the Blast Radius being a a Circle, just make it a cube. XYZ. so it will be easier to record.

And for the Sake of Graphics and Computer RAM, I suggest the maximum Blast Radius in 9999 Meters and the Visual Effects of the Exploding Missile Remains the Same. Even though the Blast Radius is Set to 2000, the Visual Blast Effects Remains at Normal Size.
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Look, I know that this is Hard Task. But I Also know that Simple Planes has a Big Potential as a Game. And if there is any way for me to Help make the Game a Better Place, then I will be more than willing to help.