Thread by @Pataramesh

So how can we quantify Salman's performance?

In the retweeted tweet I did a tech. based estimate

However due to the graph from the launch we can work with hard numbers

Here a step by step recipe, with the result of 8% empty mass at low l/d ratio: An impressive performance

1/5

https://twitter.com/Pataramesh/status/1262317217955418112

In my latest blogpost I show how the calculation for modelling a missile is done: Its no rocketscience...

- Model the Ghadr 1st stage via its officially published parameters

- Modify the model with a payload that would result in the 2800m/s delta v from the graph

2/5

- Create a estimation model of the Salman from its outside dimensions and a reasonable estimated Isp (270s-290s).
The rest of the calculated modified Ghadr payload is for the 3rd stage and sat

- Look at what structural ratio this Salman would need to have to create 2420m/s

3/5

- Model a 3rd stage and a estimated sat payload with all subsystems from the mod. Ghadr's payload budget minus Salman.
This can have many uncertainties as details are unknown.

Up to the Salman part however this calculation is quite accurate.

4/5

A structural ratio of just ~0,8 (the lower the better) for such a low l/d ratio stage, would be among the best known in the world

An elongated version could push it down to <0,7

As of 2020 this represents state of the art

It opens the gate to high performance compact BMs

5/5