The pros and cons of silo launching

[PistolPete]

With launch vehicles such as the Dnepr and Start-1 delivering payloads to LEO via a silo launch on a regular basis, it would appear that the concept of using this method for converted ICBM launch vehicles.<br /><br />However, what are the pros and cons of using this on a larger scale?<br /><br />It appears to me that it would be easier to verticaly integrate the stages in a silo than on an above ground complex.<br /><br />But are there any issues like increased vibration and back pressure because of the use of larger engines on bigger launch vehicles? <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>

 

[qso1]

Silos normally built for launching ICBMs are usually not intended to be reloaded for reuse because of damage that occurs in a silo launch. The shockwave from the exhaust is largely directed above ground through ducts but some damage will still occur along the launch tube and associated work platforms.<br /><br />The Russians got around this problem with a technique called "Cold launching" which means ejecting the missile from the tube on compressed gas and then firing the engine above ground.<br /><br />They launch commercial Dnepr LVs from silos probably because its cheaper to use an existing silo than to build an above ground facility.<br /><br />Pros and cons, I would imagine there would be pros and cons to either technique. I don't see any overwhelming advantage of one over the other. If silo launching does turn out to be advantageous, you can bet future commercial launchers will utilize this method of facilitating processing and launch. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[josh_simonson]

The silo is more to protect the rocket than anything else. It would probably be much cheaper to have ICBMs in above ground silos, but then they could be taken out by an explosion nearby. Having the missle such that nothing sticks up means that it will survive anything but a direct hit.

 

[bpcooper]

Start-1s are launched from a missile launching vehicle, not a silo. I am not sure about Dnepr. <div class="Discussion_UserSignature"> <p>-Ben</p> </div>

 

[shoogerbrugge]

You could say Start are launched from mobile silos. To prevent damage they use the "cold launch" method as well, just from a large truck based platform. <br /><br />The Dnepr can be considered a 211ton bullet, propelled by black gas out of canister and only then ignition. I guess that it does pose limits to the g-forces, vibration and acoustic loads a payload on such launch vehicles must be able to handle.<br /><br />I reckon that the acceleration of a ICBM is somewhat different from a normal launch vehicle.

 

[bdewoody]

I see no advantage to using silos for orbital launches except maybe in cases where a former ICBM booster has been reconfigured with a satellite load and to save money it wasn't removed from the silo. <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[syndroma]

> <i>The Dnepr can be considered a 211ton bullet, propelled by black gas out of canister and only then ignition.</i><br /><br />This system is usually referred in Russian as PAD - powder accumulator of pressure.<br /><br /> /> <i>I guess that it does pose limits to the g-forces, vibration and acoustic loads a payload on such launch vehicles must be able to handle.</i><br /><br />In the video of EROS-A launch, Start LV is seen lifting out of the canister very smoothly. When it leaves the canister, you can see the first flash - PAD gases contact with air and burn out. In a moment, the first stage ignites and LV accelerates really fast.<br />So, I don't think "cold launch" adds any additional limits. If a payload can survive a ride on a ICBM, it survives the launch.

 

[syndroma]

Yes, indeed. Situation even worsens if we talk about launch from submarine...<br />Solids improve things a bit, though.

 

[vulture2]

Yes, with a liquid fuel rocket one definitely likes to see it come up to full thrust before committing to launch. I've seen both Delta and Shuttle shut down after main engine ignition. The only real disadvantage of above gound launch is exposure to the weather; the Delta (II and IV) uses a mobile service tower; it could be difficult to get it back in place if bad weather rolls in suddenly but it's still simpler than blasting a big rocket out of a silo.<br /><br />Some Navy missiles do use reusable tube-type launchers and ignite in the tube but cleaning the corrosive solid-fuel residue from the launch tube can be problematic. I think the Peacekeeper was the largest US rocket to be silo launched, and it is much smaller than the EELVs.

 

[edkyle98]

The main "pro" for Dnepr and its ilk is that the launch vehicle system can be used pretty much "as-is" with very little modification from their ICBM origins. <br /><br />The "con" of silo launching would be that it would limit launch vehicle size. Peacekeeper (MX) and Dnepr are probably the heaviest silo-launched rockets (both are cold-launched). Like Dnepr, the Taurus and Athena space launchers derived from Peacekeeper are rather limited in terms of maximum orbital payload. Heavy payloads require big rockets that for all practical purposes must be launched from above ground pads.<br /><br /> - Ed Kyle

 

[PistolPete]

I am definatly suprised that the Dnepr has the successfull launch rate that it does. According to Astronautix.com most of the failures with the ICBM version came at the begining of the program, with only six failures out of 39 total launches. Not bad for a launch vehicle that spends the first few seconds of it's life as a mortar round. The Russians must have built some uber-reliable engines during the cold war. I guess that's why they stuck with hypergolic fuels, for the guaranteed start just about every time <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>