This is the first mod/tweak i have uploaded to the nexus so be kind. 
I did not like the fact that the jetpacks in fallout 4 ran on AP and have a height limit,
I have tried to fix that by removing the AP drain and setting the max height based on the time you are in the air.
I have also slowed the jetpacks speed so that its not too overpowered.
The mod comes in two different versions:

version 1 which has 5 options:
15 seconds or 30 seconds(ish) of flight recommend vanilla replacement.
45 or 60 seconds(ish) or Unlimited(10min) of flight which are all OP in my opinion.
and version 2 info below
you will reach the max height in half the total flight time with all version 1 options.
so with the 15 second option you will reach your max height in 7/8 seconds or so.
also the jetpacks power has been reduced to stop you flying into orbit this also allows you move forward and backward more reasonably
that said if you leave off the power for to long you will not be able to ascend again until you land.

F.Y.I, All tweaks in this mod can be achieved with console commands but can be a hassle to type in every time you play. 
but if you want the same affect as this mod with out using any .esp(s) or want to tweak it your self
these are the four settings i changed in all FJetPack Tweaks v1a options with FO4Edit:

1. fJetpackThrustInitial = 768                             (my version = 103)
2. fJetpackTimeToSustained = 0.15                     (my versions = 30 in v1a15) (60 in v1a30) (90 in v1a45) (120 in v1a60) (1200 in v1aUnlimited) respectively.
                                 ^^These two affect power                        ^hole number not decimal
3. fJetpackDrainSustained = 64                            (my version = 0)<
4. fJetpackDrainInital = 64                                   (my version = 0)<^These two affect AP drain
^                         ^^^^not a typo
^<These are the default values that are in the vanilla game
that i have edited to make this mod but to change them them ingame
no mod required open the console and type setgs
then the value you want to change eg:
setgs fjetpackthrustinitial 10000 which would probably launch you in to space.

Added Version 2 it has more of a sustained and level flight than version1a it offers 30 seconds(ish) of flight time if you use my recommend settings (99.5) but unlike any version1a file you ascend for 10 seconds and descend for 20ish
it is semi configurable with only one value to change (more info below)
BUT YOU WILL HAVE TO ETHER ENTER THE VALUE VIA CONSOLE COMMAND EVERY TIME YOU PLAY
OR EDIT YOUR FALLOUT4.INI FILE YOU WILL ONLY HAVE TO EDIT YOUR FALLOUT4.INI ONCE
(unless something overrides it like the launcher or you want you want to add more power) 
OTHERWISE THE JETPACK DOES NOT GET YOU OFF THE GROUND!!! 

If you do not mind editing your fallout.ini file this is the command with the value i suggest you add, it go's in the [General] section:
sStartingConsoleCommand=setgs fJetpackThrustSustained 99.5 
The jetpack is still configurable installing this way via console command but will reset to the value above when you leave and re-enter the game.

if you want to add it ingame or change the power open the console and type:
setgs fJetpackThrustSustained 99.5
or 99.6 or 99.7 or 99. you get the picture to increase power/flight time (more info below)

thanks to b6lph6gor6 for telling me this command.
increasing the fJetpackThrustSustained will add more power and flight time to the jetpack,
reducing it lowers the power and flight time with so long as the rest fjetpack settings remain the same.
Sorry but i can not seem to find this value with FO4Edit and that is why you have to enter it manually.

The setting i used in the V2a download are as follows:
fJetpackThrustInitial = 250
fJetpackTimeToSustained = 0.1
fJetpackDrainSustained = 0
fJetpackDrainInital = 0
                     ^^^^not a typo
fJetpackThrustSustained = 99.5 <<< this is the value you need to add,
to customize your jetpacks power in Version 2 i suggest changing it in increments of 0.1
a value of 99.5 gets you about as high as the roofs in concord
a value of 99.9 gets you about as high as the roofs in Lexington
a value of 100 lets you fly forever you just keep ascending
anything higher than 100 just increases the upward force applied.

If you want more info about what each setting does you can find it here:
https://m.reddit.com/r/fo4/comments/3vvj7x/tweak_your_jetpack_xpost_from_rfalloutmods/