Thanks! I highly doubt a commercial company would discuss anything to do with money, other than what they've been allocated by NASA. SpaceX give some loose prices for their launch services, but you can expect nothing else from these people.And that's totally understandable.
SNC added they are also determining the forward path for both the FTA and the third Dream Chaser – known to be the Orbital Vehicle (OV) – meaning there is no official word on whether the FTA will be the first Dream Chaser to fly a test flight in space, ahead of the OV which will be the Dream Chaser capable of carrying out commercial crew missions to the ISS.
I want to see this thing fly. I mean, I REALLY want to see this thing fly!
Quote from: Lee Jay on 12/10/2012 03:08 pmI want to see this thing fly. I mean, I REALLY want to see this thing fly!Many people would. It is hands down the most radical aerospace vehicle with a potential to fly in the next 5 years.
I've always thought it was a shame that Enterprise was never upgraded from a flight test article (FTA) to an orbital vehicle (OV).
Quote from: Todd Martin on 12/11/2012 12:59 am I've always thought it was a shame that Enterprise was never upgraded from a flight test article (FTA) to an orbital vehicle (OV).I always wanted to see that happen, and I thought it might following both Challenger then Columbia. Apparently, thought, every time they built a new orbiter, they found more and more ways to shave more weight. The FTA airframe was apparently too heavy to be worth conversion.On the cost effectiveness issue, I would think a high flight rate would make the difference. This vehicle should be much more reliable as a reusable vehicle than STS was and her turn around time could become substantially shorter. The TPS issue is substantially less as top-mount on the LV. The highest number of reuses for a capsule that I can remember reading is 10, but I could see a DC being re-certified through 200 flights. Couple that with RTLS and no well-deck ship necessary for recovery, amortized costs over a high flight rate just seems to favor this vehicle.
On the cost effectiveness issue, I would think a high flight rate would make the difference. This vehicle should be much more reliable as a reusable vehicle than STS was and her turn around time could become substantially shorter. The TPS issue is substantially less as top-mount on the LV. The highest number of reuses for a capsule that I can remember reading is 10, but I could see a DC being re-certified through 200 flights. Couple that with RTLS and no well-deck ship necessary for recovery, amortized costs over a high flight rate just seems to favor this vehicle.
I always wanted to see that happen, and I thought it might following both Challenger then Columbia. Apparently, thought, every time they built a new orbiter, they found more and more ways to shave more weight. The FTA airframe was apparently too heavy to be worth conversion.On the cost effectiveness issue, I would think a high flight rate would make the difference. This vehicle should be much more reliable as a reusable vehicle than STS was and her turn around time could become substantially shorter. The TPS issue is substantially less as top-mount on the LV. The highest number of reuses for a capsule that I can remember reading is 10, but I could see a DC being re-certified through 200 flights. Couple that with RTLS and no well-deck ship necessary for recovery, amortized costs over a high flight rate just seems to favor this vehicle.
Quote from: TomH on 12/11/2012 03:20 amI always wanted to see that happen, and I thought it might following both Challenger then Columbia. Apparently, thought, every time they built a new orbiter, they found more and more ways to shave more weight. The FTA airframe was apparently too heavy to be worth conversion.On the cost effectiveness issue, I would think a high flight rate would make the difference. This vehicle should be much more reliable as a reusable vehicle than STS was and her turn around time could become substantially shorter. The TPS issue is substantially less as top-mount on the LV. The highest number of reuses for a capsule that I can remember reading is 10, but I could see a DC being re-certified through 200 flights. Couple that with RTLS and no well-deck ship necessary for recovery, amortized costs over a high flight rate just seems to favor this vehicle.IIRC, the DreamChaser will still have a turnaround time of 2 months between flights. That is mostly because of the TPS needed a lot of service time. This is IMHO the biggest problem with the concept of the DC, the shape requires a comples TPS like the shuttle's was and that means a lot of inspection work. That will raise the price of operating it.
What do you mean by "most radical"?
I thought I read that the TPS was easily replacable, since it was part of a lower shell that comes off in 1 piece. All they need to do is build up a supply of flight-ready TPS. I doubt any vendor will need to re-fly the same vehicle in less than 2 months anyway.
But regardless of the nature of Dream Chaser’s landing, Sierra Nevada is currently looking at a two-month turn-around of the vehicle between flights to LEO.In those two months, large-scale sections of the spaceplane’s Thermal Protection System tiles would be replaced if needed – with whole tiles being replaced (even if just for a scratch) instead of repaired, as was the case with Shuttle.
The problem with this is not the availability of the vehicle but the cost of servicing it. 2 months of work for highly specialized personell means a lot of cost, not to mention the materials for the TPS itself.This will make it difficult for the DC to compete with the capsules.
Hopefully thats true, their only shot I would think is to be able to beat SpaceX on cost? But then the Atlas V is much more expensive than a Falcon 9
Slight update to the article, I've removed the White Knight 2 graphic showing Dream Chaser as that is now confirmed to be no longer an option.
Quote from: Chris Bergin on 12/12/2012 01:10 amSlight update to the article, I've removed the White Knight 2 graphic showing Dream Chaser as that is now confirmed to be no longer an option.That's disappointing; that would have been a beautiful air drop (maybe even air launch test using the hybrid engines) to watch. Phooey.
Quote from: TomH on 12/13/2012 08:59 amQuote from: Chris Bergin on 12/12/2012 01:10 amSlight update to the article, I've removed the White Knight 2 graphic showing Dream Chaser as that is now confirmed to be no longer an option.That's disappointing; that would have been a beautiful air drop (maybe even air launch test using the hybrid engines) to watch. Phooey. This doesn't mean they aren't going to do this, it just means they aren't going to do it with that particular carrier aircraft.
Would it be possible to use an Air-Crane helicopter again (as they did for the captive-carry test) or does it have to be an airplane?
Can they get up to the altitude / flight speed they want with the Air Crane ? Does NASA still have a B-52 that can be used as a carrier aircraft, or is the DreamChaser too big to fit under the wing ?
I'm thinking, is it too late to bring the last SCA out of retirement to carry Dream Chaser? It looks like there is some precedent with Phantom Ray.
Using a flying B-52 might still be possible such as the plane that flew the X-51 (B-52, tail number 050), a pylon "extension" would probably be needed and one was built for the X-38. I don't know if that extension still exists as the aircraft it was used on was retired (Tail number 008). If that extension is available and SNC was able to use and modify it, then a B-52, in theory, can be used for the drop tests.
Can anyone tell me why the WK is no longer an option for the DC drop tests? I must have missed that part.
Gliders are frequently towed. If the Dream Chaser can take off on its wheels then a fast, high flying aircraft may be able to get it into the air.
Quote from: Elmar Moelzer on 12/14/2012 02:09 pmCan anyone tell me why the WK is no longer an option for the DC drop tests? I must have missed that part.Reportedly over concerns that use of the vehicle will delay flight testing of SpaceShipTwo. They also had concerns about potential damage to the carrier aircraft
Could they possibly see DC as an airlaunched hybrid-powered competitor to SS2?
Quote from: A_M_Swallow on 12/14/2012 06:33 amGliders are frequently towed. If the Dream Chaser can take off on its wheels then a fast, high flying aircraft may be able to get it into the air.Yeah, gonna take more than a Piper Pawnee to tow that glider!
Quote from: vt_hokie on 12/14/2012 03:24 pmQuote from: A_M_Swallow on 12/14/2012 06:33 amGliders are frequently towed. If the Dream Chaser can take off on its wheels then a fast, high flying aircraft may be able to get it into the air.Yeah, gonna take more than a Piper Pawnee to tow that glider!DC has no front landing gear (just a skid) and a normal landing speed above 190 knots. I'm not sure it could be towed given those particular attributes.
Recall that in December 1997-February 1998 NASA sucessfully towed a F-106 behind a C-141 in the Eclipse Project. http://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-02-DFRC.htmlMay not be practical for DC since the loads on the structure would be different for a nose tow attachment than the top of the fuselage mount. Trivial pursuit: one of the test pilots of the F-106 was Mark "Forger" Stuckey, now a pilot on SS2.
Quote from: JAFO on 12/15/2012 08:37 amRecall that in December 1997-February 1998 NASA sucessfully towed a F-106 behind a C-141 in the Eclipse Project. http://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-02-DFRC.htmlMay not be practical for DC since the loads on the structure would be different for a nose tow attachment than the top of the fuselage mount. Trivial pursuit: one of the test pilots of the F-106 was Mark "Forger" Stuckey, now a pilot on SS2. The Kelly Eclipse was meant to have much larger wings than that. I dont think the DC is a good enough glider to be towed, but I may be wrong here.
Not sure how comparable this prototype is with the DC, but I guess towing might be an option after all (if they dont run into stability problems).
If you are curious about lifting bodies have a look at my thread here...http://forum.nasaspaceflight.com/index.php?topic=29126.0
Quote from: Rocket Science on 12/15/2012 08:34 pmIf you are curious about lifting bodies have a look at my thread here...http://forum.nasaspaceflight.com/index.php?topic=29126.0The M1F2 was a plywood over welded metal tubing design mostly to demonstrate it could glide at all. BTW I thought that DC is moving to "skids" or metal brushes rather than wheels. I'd guess the friction would be difficult for a rolling towed takeoff. A high(ish) altitude drop with the hybrid rocket to get the rest of the altitude and speed needed seems the most plausible way to widen the envelope if WK2 is not available I think DC is small enough to be dropped out of a big carrier aircraft but that's a whole different area to explore.Thanks for the zero length launch video. I would not have believed they ever managed it with a crewed vehicle, although I was aware some of the cruise missile designs of the 50s were baselined with it.
Looks like the Dreamchaser project is starting to hit some unexpected realities. Wonder how soon until the Stratolaunch lifter is ready? Several years away?
In orbit? Looks like they are having trouble just getting Dreamchaser off the ground for this droptest. Might be the Spruce Goose of spaceflight. As for a rocket assisted first test flight, I would say that is very unrealistic with a lifting body design.
It is not a technical or design problem with DC... The problem is with Scaled, ask them for motives...
Quote from: Rocket Science on 12/16/2012 12:19 pmIt is not a technical or design problem with DC... The problem is with Scaled, ask them for motives...What's Scaled got to do with it?VG owns WK2.
Did not Northrop Grumman buy scaled?
http://www.businesswire.com/news/home/20121005005907/en/Virgin-Galactic-Acquires-Full-Ownership-Spaceship-CompanyMe smells Sir Richard me thinks...
Quote from: Rocket Science on 12/16/2012 12:57 pmDid not Northrop Grumman buy scaled? True. while it's not exactly hidden NG don't seem to make a big thing of it and Scaled certainly don't go out of their way to remind people they are actually owned by anyone. Quotehttp://www.businesswire.com/news/home/20121005005907/en/Virgin-Galactic-Acquires-Full-Ownership-Spaceship-CompanyMe smells Sir Richard me thinks... Given Sir Richard's approach is much more Elon Musk than Jeff Bezos this is very low key by his standards.Scaled have a reputation for brilliant design and manufacture of 1 off or 2 off aircraft. This was problematical for an ongoing business. This suggests that VG are happy with the design and prepared to commit and freeze it. Odd as I though they still had more of the test programme to complete. OTOH if that's the case then (in principle) anyone wanting a new WK2 could just buy it from TSC, although that's likely to be quite a bit more expensive than renting time.Note that in practice I doubt this will make any substantial change to the operations of TSC or VG, with the possible return of seconded staff back to Scaled. Too bad about SNC being too big for an air drop from a transport aircraft. Not quite as small as I thought. I suggested the heli drop and rocket assisted climb because it seemed the simplest fit to what they've already done. On a limited budget (and there's is very limited) that seems like a good idea. I agree this will fly long before Stratolaunch if the funding is there. There is just so much less basic engineering, design and mfg to do. The funding is the issue. So the question is how the negotiations on averting the drive off the fiscal cliff in 15 days time are going.
Which would allow for better testing, riding on top of the plane, like Enterprise on the 747, or being suspended under the plane like the HL10 with the B-52 or SSx with the White Knight ?
Quote from: Lurker Steve on 12/19/2012 02:17 pmWhich would allow for better testing, riding on top of the plane, like Enterprise on the 747, or being suspended under the plane like the HL10 with the B-52 or SSx with the White Knight ? The "problem" with the SCA, (747) is the need to build new positional and mounting brackets for the DC. There is also an "issue" if the DC can generate enough "lift" to clear the top of the SCA during a "drop" test. (The Shuttle wings provided enough "glide" for a clean seperation as long as the SCA dove away at full power. The DC might not have enough lift to do the same)This would be an issue for ANY top mounted release though, that includes the AN-225. (IIRC there are a couple of other modified "airframes" in Russia for top carry but the main "problem" still remains)In many ways the "drop" (B-52/WK2) method would avoid the majority of the issues from top or cargo drop methods, but it then again requires an Aircraft capable of carrying the DC to drop altitude and releasing it. I suspect the Skycrane is going to have to suffice for many of the early tests, but "I" don't see them doing rocket boosted tests from there.Then again thinking on the subject I recall a "mod" for the Orbiter sim where you have a set of wings and engines that you attach to the baseline "Orbiter" vehicle that allows you to fly the vehicle to its own air-launch position. All cockpit controls and aircraft interfaces run through the cockpit of the DC in this case and it flies around like a "normal" aircraft until the drop point. The "aircraft" portion would then self-recover under remote or on-board guidance and the DC would fly the rest of the profile on its own. This could be useful both for testing and at an advanced level it might provide for suborbital flights.Something like that might be an interesting "aside" to study for the DC at some point...Randy
The AN 225 really isn’t going to need much in the way of internal structural bracing since she could carry an orbiter on her back. As far as mods go she already has the hard points to mount a rack to. As long as the rack is high enough and in clean air, separation should be possible.
The handing qualities of the DC should be fairly close to a HL-20 I simmed years back... There is nothing “evil” in a lifting body that seems to spook a lot of folks who don’t understand its aerodynamics (not aimed at anyone in particular). No big deal for any competent pilot, much better than me, espicially a former NASA Shuttle commander... CFD and a wind tunnel can verify any problems ahead of time.
Another option is to "not fly” the DC off the 225. A long rack (mounted up top) with rollers can allow her to slide off the rack behind the 225 safely using simple aero drag and or a drogue chute at the rear of DC. HMX will know what I’m talking about... Like I tell my applied physics students... “Lateral thinking people... lateral thinking”...
Since we're in the world of speculation, is there any way to hang it under a commercial airliner-sized a/c a la Orbital's L1011?
Here is a link for L/D of lifting bodies compared to the X-15 and Shuttle just for reference... Not as good as my first glider a Blanik L-13, but good enough... http://ia600609.us.archive.org/23/items/nasa_techdoc_19990052613/19990052613.pdf
What altitude does it need to be dropped from and what speed?I can't help thinking of using a blimp.It would be great PR for one of the blimp or modern Zeppelin companies.
Hey Randy,Yup, wake turbulence would have to be dealt with in the flight profile, such as the 225 will have to pitch down and bank away, DC will have to pitch up slightly and may need to bank slightly opposite. The vortices descend and DC will want to stay out of them... That’s where the wind tunnel time comes in handy. The SNC folks seem very methodical in their approach and I’m sure they will come up with a solution...
I mean if you REALLY want to get "cheap-and-easy" Jordin Kare suggested a down-and-dirty "14th Century Launch Assist" concept at one point that would be perfect Stretch a cable across the Grand Canyon, (one side is higher than the other and the vehicle would be on the "high" side) with one end attached to the vehicle and the other a very large "bucket" of water. "Knock" the bucket off the far side and let physics have it's way Thanks! I was actually looking for that one recently for something else I was referencing and couldn't figure out where/if I downloaded it
Quote from: RanulfC on 12/20/2012 06:30 pmI mean if you REALLY want to get "cheap-and-easy" Jordin Kare suggested a down-and-dirty "14th Century Launch Assist" concept at one point that would be perfect Stretch a cable across the Grand Canyon, (one side is higher than the other and the vehicle would be on the "high" side) with one end attached to the vehicle and the other a very large "bucket" of water. "Knock" the bucket off the far side and let physics have it's way Thanks! I was actually looking for that one recently for something else I was referencing and couldn't figure out where/if I downloaded it A few years ago a documentary recreated the plan to escape from the Colditz PoW camp in WWII by building a glider using bedsheets. The launch assist was a bathtub filled with concrete. The flight was viewed as too high risk so they used radio control and weights to simulate the 2 person crew. It take off and reached the landing area safely.However you're still pretty close to ground level.
What the heck does this have to do with anything?
Quote from: Robotbeat on 12/27/2012 03:29 amWhat the heck does this have to do with anything?Well with WK2 unavailable for widening the flight envelope how else can you get the altitude and speed you need to test its landing range?
The "Super Valkyrie"?
Quote from: vt_hokie on 12/27/2012 04:34 pmThe "Super Valkyrie"?I think they need an aircraft that flew some time this century.
I have to ask this question so, sorry. What happens if Dreamchaser cannot get a ride?
Quote from: mr. mark on 12/27/2012 07:55 pmI have to ask this question so, sorry. What happens if Dreamchaser cannot get a ride?Wonder if the Star Grazer L-1011 is available from Orbital, since the Pegasus don't have many missions lined up.
Since we are still discussing this allow me to give you another option. Jet airliners often ferry extra engines on a pylon beneath their wings. Theoretically they could adapt one under a Boeing 747 or a DC10 for example with sufficient clearance for DC... Like I keep saying there are many alternatives all that is required is “lateral thinking”...
Quote from: Rocket Science on 12/28/2012 12:00 amSince we are still discussing this allow me to give you another option. Jet airliners often ferry extra engines on a pylon beneath their wings. Theoretically they could adapt one under a Boeing 747 or a DC10 for example with sufficient clearance for DC... Like I keep saying there are many alternatives all that is required is “lateral thinking”...Now this I did not know. I'd always figured they'd put the engine on a standard engine pod location and fly with 3 live engines (thinking further I can see this being difficult with modern 2 engine designs). Is this a design certification (IE all aircraft of a type can do it) or does it need special clearance from the relevant authorities?The ground clearance should be adequate but the inter-pod separation?It's something I've never seen before but I'm guessing the joker is in the paperwork. I strongly doubt you can hire an aircraft from an airline, hang DC on the pylon, run the tests and hand the aircraft back to them. But definitely something I'll be filling in the "More common than you think" drawer. [edit]Read one of the links posted. The DC-8 hit M1.01 in a dive from 52kft to 41kft in 1961. I did not believe any big commercial jet had deliberately done this. http://www.airliners.net/aviation-forums/tech_ops/read.main/200315/Reply from Viscount724.And in the press release for it (a bit suspicious) the implication is even that it is "routine" and they were going to ship it to a customer. http://www.dc8.org/library/supersonic/index.phpThis link shows a fairly detailed description of the DC-8 flight which might be relevant should you could consider repeating it.http://www.dc-8jet.com/0-dc8-sst-flight.htmSkip the drop test and drop the whole aircraft? [edit]
Quote from: john smith 19 on 12/28/2012 07:15 amQuote from: Rocket Science on 12/28/2012 12:00 amSince we are still discussing this allow me to give you another option. Jet airliners often ferry extra engines on a pylon beneath their wings. Theoretically they could adapt one under a Boeing 747 or a DC10 for example with sufficient clearance for DC... Like I keep saying there are many alternatives all that is required is “lateral thinking”...Now this I did not know. I'd always figured they'd put the engine on a standard engine pod location and fly with 3 live engines (thinking further I can see this being difficult with modern 2 engine designs). Is this a design certification (IE all aircraft of a type can do it) or does it need special clearance from the relevant authorities?The ground clearance should be adequate but the inter-pod separation?It's something I've never seen before but I'm guessing the joker is in the paperwork. I strongly doubt you can hire an aircraft from an airline, hang DC on the pylon, run the tests and hand the aircraft back to them. But definitely something I'll be filling in the "More common than you think" drawer. [edit]Read one of the links posted. The DC-8 hit M1.01 in a dive from 52kft to 41kft in 1961. I did not believe any big commercial jet had deliberately done this. http://www.airliners.net/aviation-forums/tech_ops/read.main/200315/Reply from Viscount724.And in the press release for it (a bit suspicious) the implication is even that it is "routine" and they were going to ship it to a customer. http://www.dc8.org/library/supersonic/index.phpThis link shows a fairly detailed description of the DC-8 flight which might be relevant should you could consider repeating it.http://www.dc-8jet.com/0-dc8-sst-flight.htmSkip the drop test and drop the whole aircraft? [edit]I don’t want to take this OT but if you are interested in engine out discussion there is more to read here:http://www.airliners.net/aviation-forums/tech_ops/read.main/308222/When it comes to using an airliner for a DC drop test there is no need to take one out of service. There are loads of these sitting out in the desert for long term storage that can be leased or purchased if the wish to and modified. Since these flights are going to be over an experimental flight test range with no paying passengers, the normal airliner regs don’t need to be complied with. Conceivably you could remove one engine from a 747, lightly load it with fuel and use the pylon to carry and drop DC from it with modifications... No need for high Mach numbers to drop DC...
Based on what I'm hearing, it looks like there will be no drop test until late 2013- 2014. It takes time to adapt out a system and look at all possibilities.
Quote from: mr. mark on 12/28/2012 02:54 pmBased on what I'm hearing, it looks like there will be no drop test until late 2013- 2014. It takes time to adapt out a system and look at all possibilities. Attaching a jettisonable parachute to DC's tail, and dropping from high altitude by helicopter doesn't sound like the sort of thing that would take till late 2013, or does it?
Quote from: adrianwyard on 12/28/2012 02:58 pmQuote from: mr. mark on 12/28/2012 02:54 pmBased on what I'm hearing, it looks like there will be no drop test until late 2013- 2014. It takes time to adapt out a system and look at all possibilities. Attaching a jettisonable parachute to DC's tail, and dropping from high altitude by helicopter doesn't sound like the sort of thing that would take till late 2013, or does it?There are definately some low altitude / low speed tests they can do with the helicopter, including the first free-flight and landing tests.
Where is Stratolaunch on the modifications to their carrier aircraft? It would certainly be large enough to handle a Dreamchaser.
Quote from: ChefPat on 12/28/2012 02:48 pmWhere is Stratolaunch on the modifications to their carrier aircraft? It would certainly be large enough to handle a Dreamchaser.A long way from even being constructed.
Quote from: john smith 19 on 12/28/2012 03:24 pmQuote from: ChefPat on 12/28/2012 02:48 pmWhere is Stratolaunch on the modifications to their carrier aircraft? It would certainly be large enough to handle a Dreamchaser.A long way from even being constructed. Are they? They've had the 2 jets for more than ten months now. How long does it take to modify them?
Attaching a jettisonable parachute to DC's tail, and dropping from high altitude by helicopter doesn't sound like the sort of thing that would take till late 2013, or does it?
There are definately some low altitude / low speed tests they can do with the helicopter, including the first free-flight and landing tests.
I think so. But if that's the case, what test(s) will a helicopter be insufficient for?
The "issue" here is "dropping from high altitude" with a helicopter. Especially with the DC lifting body.We've got several "facts" to work with already:The stats for the Skycrane can be found here:http://www.ericksonaircrane.com/Note: Maxium "hook" weight is the important figure here. The S-64E can lift up to 9,072kg (20,000lbs) while the S-64F can lift up to 11,340kg (25,000lbs) with a "maxium" cruise speed of 115-knots (212kph/132mph) for the former and 104-knots (192kph/119mph) with the latter. This is important for several reasons but the "biggie" is that these figures (for the Skycrane(s)) is for rather LOW altitude, well below 20,000ft. (As a comparison you can see the Shuttle A-and-L tests here, ya "wikipedia" I know but the general data is accurate, http://en.wikipedia.org/wiki/Approach_and_Landing_Tests )The "highest" altitude recorded for the "type" for the S-64 is held by an earlier version for the US Army the "CH-54" which reached a maxium altitude of 36,000ft but this was with NO load, limited fuel/crew, no forward speed, etc so that it COULD reach that high. "Typical" maximum operational altitude is listed as a bit over 18,000ft but again that's NOT going to be with a full load, nor at "high" speed. Helicopters like all "active" lift vehicles have a limit of what they can lift that goes DOWN with altitude, as does speed. (You have to trade "lift" power for speed power) So in general we're looking at a "probable" release at or around 10,000ft at most."Assuming" the DC-ETV mass' somewhat close to the "operational" launch mass of around 11,340kg the Helo flying it must be the F model which means a lower intial speed to start off with. If it's below 9,000kg they could use the E model but then the "flying" characteristics will be a lot different than the "actual" DC orbiter vehicle.
It could very easily be MORE than a year or two to get all the data needed to even see if they actually CAN use a helo to do "free-flight" drop tests for the DC-ETV. In general the DC-ETV has to "fall" fast enough, from high enough to generate a viable speed of almost 200-knots, (370kph/230mph) from a possible "maximum" drop speed of between 104 to 115-knots,(192kph/119mph to 212kph/132mph) and that's non-trivial.As an example I'd point to the fact that NASA did this testing type mission when evaluating the low-speed handling characteristics of the "staight-wing" versus the "delta-wing" versions of the Shuttle. Most of them still ended up "pranging" the nose of the model pretty good because they simply couldn't generate enough lift from a zero-speed drop IIRC.And that's a WINGED vehicle and not a lifting body
They really need a "carrier" aircraft for flight testing both to give it the intial minimum speed and a better altitude to work from. Which brings me to the idea of "hanging" the DC-ETV from a "normal" airliner mounting station. My take is its do-able as long as the station can be configured (a mounting pylon/bracket) and is able to handle the load. Which points to a particular issue; mass. Most of the engine weights I'm seeing do not exceed 4,000kg to 5000kg which is far below even the "low" estimated mass of the DC-ETV of 9,000kg. And that doesn't take into effect the mass of the "pylon" and mounting system. It's possible they could make a mount that would "span" say an inboard engine mount and the ferry engine mount but even then the total "weight" capacity of the mounts probably won't be enough to carry the load.
Now if the overall mass of the DC-ETV IS lower than anything listed they could very well use such an arrangment to test fly the vehicle HOWEVER the "tests" will be very far off the mark for any comparision to the "real-thing" because of the lift/drag/mass-ratio of the test vehicle.(A low mass test vehicle will glide and generally fly much better than something that is close to the actual planned vehicle mass which would throw off any results)
On the subject of dropping lifting bodies from helicopters...It's not like we have no experience doing this. Anyone remember Project Parawing? Hyper-X? X-40A? All dropped from helicopters at rather modest altitudes - all landed without incident (In the case of the X-40A multiple times). We (the metaphysical we) know how to do this.IMNSHO, much ado about nothing.
In a DC thread some time ago people expressed doubt that one nozzle design could be chosen that would work in vacuum and the atmosphere. I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble) but if it is, then the hybrids couldn't be used for drop tests
...If the RCS can also operate at all altitudes, then technically DC doesn't need any carrier aircraft at all for low altitude test: back it up to the end of a long runway, fire the hybrids, then at ~200mph fire the down RCS jets to pick the nose up, fly for a few seconds, cut the hybrids and land. Note: this is not a a serious suggestion, but it certainly would be fun to see tried!
It sounds like the best guess is a helicopter will be used for low speed low altitude tests. For higher speed tests, we may have wait quite a while until SNC is ready to install/fire the hybrids or design/qualify mounts for an as yet unknown carrier aircraft.
Quote from: adrianwyard on 12/30/2012 06:55 amIt sounds like the best guess is a helicopter will be used for low speed low altitude tests. For higher speed tests, we may have wait quite a while until SNC is ready to install/fire the hybrids or design/qualify mounts for an as yet unknown carrier aircraft. Well the hybrids are a fairly well characterized system and SNC have a relationship with the suppliers. The high altitude balloon drop is starting to look almost sensible.
Quote from: john smith 19 on 12/30/2012 11:03 amQuote from: adrianwyard on 12/30/2012 06:55 amIt sounds like the best guess is a helicopter will be used for low speed low altitude tests. For higher speed tests, we may have wait quite a while until SNC is ready to install/fire the hybrids or design/qualify mounts for an as yet unknown carrier aircraft. Well the hybrids are a fairly well characterized system and SNC have a relationship with the suppliers. The high altitude balloon drop is starting to look almost sensible. Aren't SNC themselves the developers of the hybrids? It sounds cavalier to suggest hybrids be fired early on in the test program (see SS2's large number of unpowered flights) but if the DC motor is as ready for flight testing as the airframe and avionics, then I guess it wouldn't be insane.
I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble)
I don’t buy that... SS1 Flew just fine and SS2 will use a similar motor to DC...
If the RCS can also operate at all altitudes,
Quote from: Rocket Science on 12/29/2012 10:23 pmI don’t buy that... SS1 Flew just fine and SS2 will use a similar motor to DC...Not relevant or applicable.
Jim, a question... Cannot SNC fit whatever sized nozzle to which ever part of the flight envelope they wish to test? It is a bolt-on operation...
Quote from: Rocket Science on 12/30/2012 01:01 pmJim, a question... Cannot SNC fit whatever sized nozzle to which ever part of the flight envelope they wish to test? It is a bolt-on operation...Most nozzles for composite SRM's aren't bolt-on
And isn't CST-100 using RS-88 for both abort (from sea level presumably) and orbital maneuvering, i.e. vacuum?
Quote from: Jim on 12/30/2012 01:43 pmQuote from: Rocket Science on 12/30/2012 01:01 pmJim, a question... Cannot SNC fit whatever sized nozzle to which ever part of the flight envelope they wish to test? It is a bolt-on operation...Most nozzles for composite SRM's aren't bolt-on Yea Jim you are right . I was thinking about the bolts around the circumference on the end case on the ground test motors. The motors are one piece composite. In that case they would have to produce motors with different optimized nozzles....Edit to add:Thinking about this a bit more... DC would have to be able to perform a Pad Abort using standard ops motors and nozzles. So why can’t a single nozzle design be used for the test flights as well?
Quote from: adrianwyard on 12/29/2012 09:51 pmIn a DC thread some time ago people expressed doubt that one nozzle design could be chosen that would work in vacuum and the atmosphere. I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble) but if it is, then the hybrids couldn't be used for drop tests I asked them specifically if the hybrids would be used for the drop tests, and Mark Sirangelo said that they would be. I think it's reasonable to assume that he knows what he's talking about given that he's former CEO of Spacedev and current head of SNC Space Systems.This was in the context of high altitude releases from carrier aircraft, not from the helicopter.
Quote from: Lee Jay on 12/31/2012 03:00 amQuote from: adrianwyard on 12/29/2012 09:51 pmIn a DC thread some time ago people expressed doubt that one nozzle design could be chosen that would work in vacuum and the atmosphere. I'm not sure if this is in fact that big a problem (shuttle SRM nozzle operated from 0-146K ft without trouble) but if it is, then the hybrids couldn't be used for drop tests I asked them specifically if the hybrids would be used for the drop tests, and Mark Sirangelo said that they would be. I think it's reasonable to assume that he knows what he's talking about given that he's former CEO of Spacedev and current head of SNC Space Systems.This was in the context of high altitude releases from carrier aircraft, not from the helicopter.Exactly Lee Jay, I remember that and that is one of the reasons that I fail to understand the concern over it. The only difference that it would be done later in the test flights as Mark stated. Circumstances have changed and perhaps other options made need to be examined including boost to climb sooner rather than later...
Quote from: adrianwyard on 12/30/2012 06:30 amIf the RCS can also operate at all altitudes, No such thing.
Quote from: Jim on 12/30/2012 12:53 pmQuote from: adrianwyard on 12/30/2012 06:30 amIf the RCS can also operate at all altitudes, No such thing.Do you say this because it's not possible to design one nozzle that's optimized for all ambient pressures? Or for some other reason?
I see the Shuttle orbiter's vernier jets were a scant 25 pounds-force, and main RCS jets were 860 pounds-force. Since DC is ~1/10th the mass of the orbiter, can we guess its' RCS will be closer in size to the Shuttle's verniers?