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-   -   TNE Only: Designing a TL 7 8 cm HE Solid Fuel Rocket (http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=39982)

snrdg082102 April 23rd, 2019 11:54 PM

Designing a TL 7 8 cm HE Solid Fuel Rocket
 
Hello all,


I thought I had asked sometime back in 2015 on how to design a solid fuel rocket. Unfortunately I cannot find the notes or the thread.


My 8 cm HE rocket warhead calculations returned a weight of 4.8 kg, a Volume of 0.96 m^3, and a cost of Cr48.


Unfortunately, I have not figured out how to calculate the solid fuel rockets per the directions on TNE FF&S Mk I Mod 1 (January 1994) p. 70.


Can anyone please walk me through building a solid fuel rocket?

timerover51 April 24th, 2019 05:02 AM

Quote:

Originally Posted by snrdg082102 (Post 601083)
Hello all,


I thought I had asked sometime back in 2015 on how to design a solid fuel rocket. Unfortunately I cannot find the notes or the thread.


My 8 cm HE rocket warhead calculations returned a weight of 4.8 kg, a Volume of 0.96 m^3, and a cost of Cr48.


Unfortunately, I have not figured out how to calculate the solid fuel rockets per the directions on TNE FF&S Mk I Mod 1 (January 1994) p. 70.


Can anyone please walk me through building a solid fuel rocket?

Here is a link to a 1944 U.S. Army technical manual covering rockets of all types used in World War 2.

http://cgsc.contentdm.oclc.org/cdm/c...9/id/312/rec/1

Somewhere online is also the DA Pam covering ammunition used by the Viet Cong. I just need to remember where it is. I think that there is also the DA Pam covering weapons used in Vietnam. I have some stuff in my handbooks on artillery as well, but I need to get them out.

timerover51 April 24th, 2019 05:52 AM

More Stuff.

Equipment guides to weapons circa 2010.
http://cgsc.contentdm.oclc.org/cdm/s.../2089/rec/1367

http://cgsc.contentdm.oclc.org/cdm/s.../2090/rec/1368

Viet Cong Ammunition Guide
https://archive.org/details/PAM381-12

Looks at the German Rocket Material.
https://archive.org/details/CatalogO...teriel/page/n1

snrdg082102 April 24th, 2019 09:45 AM

Morning timerover51,



Quote:

Originally Posted by timerover51 (Post 601092)
Here is a link to a 1944 U.S. Army technical manual covering rockets of all types used in World War 2.

http://cgsc.contentdm.oclc.org/cdm/c...9/id/312/rec/1

Somewhere online is also the DA Pam covering ammunition used by the Viet Cong. I just need to remember where it is. I think that there is also the DA Pam covering weapons used in Vietnam. I have some stuff in my handbooks on artillery as well, but I need to get them out.


Thank you very much for the link which has been added to my reference folder.

snrdg082102 May 5th, 2019 07:04 PM

Hello again timerover51,


First my apologies for the delay in getting back to you since I did notice that you had supplied more material to the original link. My guess is that I was typing my reply and missed the notification.


That you for the additional material.





Quote:

Originally Posted by timerover51 (Post 601095)


timerover51 May 6th, 2019 12:18 AM

You might want to check to see if any nearby library has a copy of Jane's Weapons System, or see if you could pick one up fairly cheap online.

snrdg082102 May 6th, 2019 12:25 PM

Morning timerover51,



Quote:

Originally Posted by timerover51 (Post 601428)
You might want to check to see if any nearby library has a copy of Jane's Weapons System, or see if you could pick one up fairly cheap online.


Thank you for the suggestions of checking my local library for or purchasing a copy of Jane's Weapons Systems. Seeing I've spent my book allowance already for the month of May, I'll have to stop by my library.


Thank you again for sharing the links and your help.


Tom Rux

snrdg082102 May 6th, 2019 01:00 PM

Hello again,


TNE FF&S Mk 1 Mod 0 (January 1994) Book II Subsystems Chapter 9 Sublight (Maneuver) Drives: Self Contained Thrusters p. 60 provides the following instructions for building a solid fuel rocket.


Th: Thrust, in tonnes, per cubic meter of engine.
*Note that solid fuel rockets have no engine volume perse; the
fuel volume is the engine volume. Solid rocket fuel (SRF) mass in
tonnes equals its volume in cubic meters. See FC note below to
calculate solid rocket thrust.

FC: Fuel consumption, in tonnes, per hour per tonne of thrust
To determine volume in cubic meters, multiply by the volume of
the fuel type. For solid rockets, simply pick a fuel mass. Divide the
mass by the FC value. The result is thrust in tonne-hours. Select
either the thrust or the duration, and the other is determined from
that. For example, 18 tonnes of TL-6 SF rocket fuel could have 2
tonnes of thrust for one hour, 4 tonnes for 30 minutes, 1 tonne
for two hours, or any other combination desired, as limited by the
maximum allowed thrust (MaxT column).

Size Efficiency: Solid-fuel rockets with less than 500 kg of
propellant (fuel) mass suffer from inefficient fuel combustion. To
determine the fuel consumption inefficiency of a solid-fuel rocket,
divide 500 by the fuel mass (in kilograms). The result is the final
fuel use multiplier. Multiply the calculated fuel consumption of
the engine by this number. However, any multiplier less than 1
is treated as 1 and any multiplier greater than 10 is treated as 10.


On the Self-Container Thrusters Table a TL 7 SF Rocket MaxT = 1,500 tonnes of thrust for one engine, FC = 7.5 tonnes per hour per tonne of thrust, FT = SRF, and Airframe = Hypersonic.


The Fuel Table shows that SRF has a Density (Volume?) of 1 and the price is Cr 2,000 per cubic meter.


From Book III Chapter 9 Munitions a TL 7 8cm HE warhead mass is 4.8 kg and the volume is 0.96 cubic meters. Using CT Striker the warhead is 5 kg and the propellant needed to travel 1 km is 5 kg.



Using the CT Striker fuel mass of 5 kg or .005 tonnes the thrust is .005/75 = 0.000667 tonnes of thrust per hour. The 5 kg is less than 500 kg which results in a fuel inefficiency value of 10 adjusting the thrust from 0.000667 x 10 to 0.00667 tonnes.

Have I followed the directions correctly?

TheDark May 21st, 2019 08:36 PM

You also need the section on Atmospheric Rockets and Missiles on page 146 of FF&S, where you'll select an average velocity and fuel mass, calculate average mass, and use velocity, average mass, and a tech modifier to figure how much thrust is required. The fuel consumption is then calculated, which gives the information needed to calculate endurance and range.

TheDark May 27th, 2019 03:06 PM

Quote:

Originally Posted by TheDark (Post 601994)
You also need the section on Atmospheric Rockets and Missiles on page 146 of FF&S, where you'll select an average velocity and fuel mass, calculate average mass, and use velocity, average mass, and a tech modifier to figure how much thrust is required. The fuel consumption is then calculated, which gives the information needed to calculate endurance and range.

Running through the Atmospheric Rockets section, using a TL 7 8cm HE warhead and 5 kg of fuel:

For the sake of this calculation, I'm using the 700 m/s launch velocity of an 8cm Flz.-Rakete Oerlikon as the average velocity. This is 503.6 km/h using the conversion formula in step 1.

Propellant mass is 5 kg. For an unguided rocket, average mass is 7.3 kg (4.8 kg warhead plus half of the propellant mass; there is no guidance or engine mass).

Required thrust is 503.6 * 503.6 * 7.3 * 0.0000009, which is 1.666 kilograms of thrust.

Fuel burned per kilogram of thrust per second is the TL 7 Solid Rocket FC of 7.5 divided by 3600, or 0.00208; this is multiplied by 10 for fuel inefficiency to 0.0208.

Fuel burned per second is 0.0208 * 1.666, or 0.0347 kilograms per second.

Fuel endurance is 5 divided by 0.0347, which is 144 seconds.

Range is the velocity of 503.6 km/h multiplied by 144 seconds and divided by 3600, which gives a range of 20.15 kilometers.

Reducing the fuel to 1 kilogram (and keeping all other numbers the same) would give a range of 2.8 kilometers.


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