Rocket Science Equation Problems

Hi i am a 'newbee' at rocket science but i have begun to make plans
for a rlv rocket, intended for people travel to space. But i have a
problem calculating Hmax (max height) whit regards to my
'configuration'. This is the specifications for my first theoretical
space tourism rocket, why am i not getting a Hmax number that sound
resonable?:

Mpayload:
4 persons * 90 kg / person = 360 kg
4 suit/misc * 50 kg / person = 200 kg
=
560 kg (1232 lbs)

Mdry (vehicle whitout fuel&oxidizer):
3000 kg

Mburout:
3560 kg

Thrust:
I have thought about using 4 rocket engines that each produce a thrust
of 1200 kg. Ttot Mliftoff (grossweight) therefore i took 1,3 *
3560 kg = ca 4628 kg of thrust.

1200 kg * 4 rocketEngines = 4800 kg

Mass ratio:
R = 8360 kg / 3560 kg = ~2,2
L = 1/2,2 = ~45% dry + payload weight

Isp engine specific impulse:
i choose a ca number lets say 250 sec because i am going to
try to get fuels and oxidizers that are easy to get! therefore the
medium isp.

Fuel&oxidizer flow:
Total thrust / isp = 17,8 kg/sec

Thrust burnout:
250 sec (/60 = 4,2min)

ok so that is my theoretical rocket,, when i apply all my numbers to
the Hmax equation to get the hight from this rlv i always get a really
low or a to high number to be true... this is the equatioin:
go=9,81m/sec/sec

Hmax = (isp*go*l*n*R)^2 / (2*go) - isp*go*tb(R*l*n*R/R-l)-l) +
Hliftoff (i will launch at SL)

could someone that is nice and have a little time make this equation
for me ?? i always get to high or to low number what am i doin wrong?

"Thrust:
I have thought about using 4 rocket engines that each produce a thrust
of 1200 kg. Ttot Mliftoff (grossweight) therefore i took 1,3 *
3560 kg = ca 4628 kg of thrust.

1200 kg * 4 rocketEngines = 4800 kg
"
I don't know if I'm following what you are saying, but if you want to
go up, without using wings, you need more thrust than gross weight of
vehicle.