Shuttle Ferry (APOD 08 July 2007)

[orin stepanek]

http://antwrp.gsfc.nasa.gov/apod/ap070708.html

It looks like a lot for the 747 to carry. I'd like to see how the 747 is reinforced inside to be able to carry such a load.
Orin

[wtwhitener]

I would like to know how they get the shuttle up on top?!!

[Case]

I would like to know how they get the shuttle up on top?!!

I suppose using a similar installation to the one they use to get it off again.

[Andy Wade]

I would like to know how they get the shuttle up on top?!!

I suppose using a similar installation to the one they use to get it off again.

Have you been to the wikipedia link? :

http://en.wikipedia.org/wiki/Image:Shut ... _point.JPG

I love the instruction they've painted on the connector block.
"Attach Orbiter Here. Note: Black Side Down"
LMAO

[Nancy D]

Does anyone know what mountains are in this photo of the shuttle being "shuttled?"

[craterchains]

I will hazard a guess and say it is the Cascades of Cal.

[iamlucky13]

I'd forgotten about the "Black Side Down" label.

The listed mass is wrong. The APOD states that the two together are about 150,000 kg. Actually, the empty 747 alone weighs 323,000 pounds (about 150,000 kg). With the shuttle mounted and a full load of fuel the weight would be over 700,000 pounds (325,000 kg).

http://www.nasa.gov/centers/dryden/news ... -DFRC.html

It looks like a lot for the 747 to carry. I'd like to see how the 747 is reinforced inside to be able to carry such a load.

Looking aft in the picture below, I can see two sets of green-painted, A-frame shaped ribs that look to be roughly where the rear of the shuttle would be when mounted. They project noticeably further into the cabin than the other ribs. I'm guessing this is the reinforcement.

[BMAONE23]

NICE IMAGE LUCKY

some other quick facts:

Performance
Airspeed limits with, and without an orbiter: 250 knots or Mach 0.6
Altitude: Typical cruise with orbiter, 13,000-15,000 ft; typical cruise unmated, 24,000-26,000 ft. Minimum temperature at altitude 15 degrees (F) (-9 degrees C)
Range: Typical mated, 1000 nautical miles (with reserves); maximum unmated, 5500 nautical miles
Fuel Capacity
47,210 gallons (316,307 lbs) jet fuel

at 250 nauts the range of 1000 nauts means that they can fly for 4 hours w/o refueling and with a capacity of 47210 gal, they burn 11802.5 gph. or 47.21 gallons per mile.

Assuming approx 3000 miles from Edwards AFB to Florida NASA, they would need to stop to refuel 2 times enroute. They should then go thru approx.141630 gal of avgas to transport the craft back to florida which would take about 14 hours with refueling stops.

With aviation fuel running (nationwide) between $5-7 per gal that means fuel costs alone are between $708,105 and $991,410 to transport the shuttle back to Florida.


I wonder if it would be cheaper to build a launch tower at edwards??

[Nancy D]

When we lived in Abilene, Texas in the 80's and 90's, at least once they stopped there at Dyess Air Force Base. We drove out to where we could see the runway and saw it. It looks pretty cool just sitting on the airliner.

[Pete]

The mounting point label is hilarious!

[...] the empty 747 alone weighs 323,000 pounds (about 150,000 kg) [...]

Fuel Capacity
47,210 gallons (316,307 lbs) jet fuel

is it common for planes to carry their own weight in jet fuel?
How is the shuttle attached to the carrier? Bolts?

[rigelan]

I think it is typical.

[orin stepanek]

Thanks iamlucky13; awesome picture. Thanks BMAONE23 for the extra info. Nancy D. Must have been really cool to see live.
Orin

[iamlucky13]

I should've given credit for where I found that photo:
http://aiaa.pr.erau.edu/past/Edwards98/ ... 8.html#SCA

Also, I managed to find some clearer photos of the interior today:
http://www.ktb.net/~billmeco/nasa747.html

is it common for planes to carry their own weight in jet fuel?
How is the shuttle attached to the carrier? Bolts?

It is typical for them to be able to carry their own weight in fuel, but in practice they will usually trade off some fuel/range for cargo capacity. If you consider the weight of the shuttle and the max take off weight of the carrier, you will see they must do this for the ferry flights, so BMAONE23's numbers are a little off.

Also, launch requires much more than just a pad. You also need the processing facilities...especially the Vehicle Assembly Building and the transporter crawlers which were investments from the Apollo days. It's cheaper to have one launch site and and carry the shuttle back to it. Plus, Edwards is at a higher latitude than Kennedy.


The shuttle attaches to the carrier aircraft using the same ball-and-socket type joints that it uses to attach to the external tank during launch. The balls on the carrier or the external tank legs fit into three sockets (two aft, one forward) on the underside of the shuttle and carry most of the loads. The ball and socket are held together by a bolt. During launch, this is an explosive bolt that is triggered by the computer to jetison the tank when empty. I'm pretty sure they use a normal bolt for ferry flights.

[BMAONE23]

Fortunately, I cannot claim responsibility for the accuracy of the numbers I supplied as they came directly from this link
http://www.nasa.gov/centers/dryden/news ... -DFRC.html
that Iamlucky13 provided. I just condenced the information and supplied the Avgas fuel prices that were current for that day.

[Andy Wade]

The shuttle attaches to the carrier aircraft using the same ball-and-socket type joints that it uses to attach to the external tank during launch. The balls on the carrier or the external tank legs fit into three sockets (two aft, one forward) on the underside of the shuttle and carry most of the loads. The ball and socket are held together by a bolt. During launch, this is an explosive bolt that is triggered by the computer to jetison the tank when empty. I'm pretty sure they use a normal bolt for ferry flights.

Talking of ball and socket joints...
My understanding is that the tiles covering the shuttle are extremely heat resistant and to my mind a hole(s) in the surface of the underside is just asking for trouble. So what do they do with the holes to get round this problem?

[iamlucky13]

No worries BMAONE23. The fact still remains that it costs a pretty penny to fly the shuttle across the country.

Talking of ball and socket joints...
My understanding is that the tiles covering the shuttle are extremely heat resistant and to my mind a hole(s) in the surface of the underside is just asking for trouble. So what do they do with the holes to get round this problem?

Good question! I actually was going to mention that originally, but decided to keep the post a little shorter.

The rear mounting points are each covered by small doors that also cover the where the fuel umbilicals from the tank enter the shuttle:
http://science.ksc.nasa.gov/shuttle/tec ... lage_2.jpg

The front mount is smaller and doesn't have it's own door, but it appears to have some sort of plug. Also, the heating is much less severe towards the center of the underside than it is near the edges.

If you look the forward mounting point is visible closeup in this picture:
http://antwrp.gsfc.nasa.gov/apod/image/ ... 14_big.jpg

[AZJames]

The ball and socket are held together by a bolt. During launch, this is an explosive bolt that is triggered by the computer to jetison the tank when empty. I'm pretty sure they use a normal bolt for ferry flights.

One would hope so, eh lucky? Then again, what was the Mars mission where some whizkid used imperial units when he should have used metric, or was it vice versa?

[iamlucky13]

lol...yes one would hope so.

It occurred to me they could use an explosive bolt to try to jetisson the shuttle from the 747 in case of emergency, but the shuttle would be uncontrolled, so there's probably more risk in that case of releasing the shuttle than just carrying it through whatever emergency might crop up.

Also, I assume they used explosive bolts for the original glide test performed with Enterprise.

By the way, the Mars imperial-metric mix-up was pretty involved. Having studied it a little bit, I understand how it happened. It was definitely preventable and embarrassing, but a lot more complicated than people give NASA credit for.

[jimmysnyder]

By the way, the Mars imperial-metric mix-up was pretty involved. Having studied it a little bit, I understand how it happened. It was definitely preventable and embarrassing, but a lot more complicated than people give NASA credit for.

Can you give us some idea of how complicated. After all, mixing up imperial/metric is a simple thing even if it occurs as part of a complicated task.

[iamlucky13]

I guess that's a fair way of saying it. It was a simple mistake, but it happened deep within the minute details of a very complicated task.


The mission this happened on was the Mars Climate Orbiter. To save costs, much of the ground control software was re-used from the Mars Global Surveyor, but of course, modified where necessary to fit the particulars of the new mission. It worked fine for the MGS, but under time pressure to get the mission ready for the launch window, the conversion factor was missed when adapting the software. Testing was limited both because of the time and budget pressure, and because the MGS had already "proven" the code was safe. The accident investigation later concluded more testing would probably have showed the error this led to, which was very subtle.

Among the duties of the software was calculating velocity based on the forces of accelleration everytime they fired the reacton control thrusters. The reaction control thrusters control the orientation of the orbiter to keep it pointed the right way. To save mass and cost, the number of thrusters was kept minimal, which required a geometry such that some of their force was rotational (desired) and some was translational (in the direction of travel). This has to be accounted for to obtain accurate navigation. Although the effect is very, very small, it adds up over millions of kilometers.

This thrust was given by given by Lockheed in pounds, but NASA works in Newtons (they now require all vendors to provide everything in metric, I believe). The modified MGS ground-control software should have had the conversion factor added. The result was the calculated effect on velocity from using the reaction control thrusters was off by a factor of 4.45. It sounds big, but it was still small enough that it did not result in an noticeable error in the limited testing they did.

In flight, this showed up as monitoring the velocity from earth showed some discrepancy between the calculations. This is expected and all missions have mid-course corrections, so it didn't raise any flags. You calculate a thruster burn based on position and velocity to fix the error. However, the error in the spacecraft calculations meant the position was in error. This error went into the course-correction calculations, so while those fixed the velocity each time, the craft was already out of position.

The end result is that instead of entering orbit at about 220 km, the MCO probably dipped as low as 57 kilometers, disintegrating due to the force and heating of drag as it skimmed the Martian atmosphere.