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1:72 SNC Dream Chaser spaceplane **FINISHED**


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I will be building the Sierra Nevada Corporation's Dream Chaser spaceplane for the group build. I will be using the NASA HL-20 resin kit from Blap! Models.

Since I am already juggling so many modeling projects, the last thing I need is one more build on my plate. Luckily, there's not much to this little kit and I hope to finish it in just a few weeks' time.

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Some modifications will be required in order to turn the HL-20 into a Dream Chaser. The RCS thruster holes are in different locations on the Dream Chaser and they will have to be filled in, and new thruster holes drilled. The back end where the egress hatch is will have to be scratch-built, and the fins will have to be squared off on the ends. I'll also need to add OMS engines and rear thruster nozzles, which I will steal from my Airfix and Tamiya shuttle kits.

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I have already started on decals to represent the belly tiles. I'm using the same artwork from my space shuttle tile set to make these. Above you see my work-in-progress so far.

I plan to begin construction of the kit tomorrow afternoon!

Edited by Hotdog
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DAY 1

4.3 hours

Build cost to date: $55.00

I began the Dream Chaser build today. A lot of time spent, with not a lot to show for it. My goal was to get the wings attached today, but that didn't happen.

I sanded off what flash and raised seams there were on the body, and removed this block from the aft bulkhead.

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No need to putty and sand where the block was, I'm going to cover the entire bulkhead with a new panel made of styrene sheet.

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I traced around the shape of the aft bulkhead onto a piece of .060" styrene sheet and cut it out. I also cut out a 1/2" hole in the center where the crew egress hatch will go.

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Here is the new backend, after super-gluing onto the body and sanding it flush around the edges. I should have used a slightly thicker sheet of styrene, but I didn't want to throw the scale off too much. I'll get back to finishing up the rear end after I round up a few more needed items.

At this point, I was ready to attach the wings. But upon further inspection of reference photos, I noticed that the wings and stabilizer on the Dream Chaser are swept further back than those on the HL-20. This will require scratch-building new ones with thicker styrene than what I have on hand. So looks like I will be making a trip to the hobby store tomorrow!

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The Dreamchaser wings are also not as slab sided. SNC gave them more of an airfoil shape. I plan to do one myself (on a scratchbuilt Atlas V booster) so I will be watching this GB a bit.

True! Which is why I need to pick up some thicker styrene sheet than what I have, for those thicker leading edges. If I am able to get the wings close to an accurate shape, I can already foresee the need to use milliput underneath the wings to blend them into the body of the craft. No biggie, just another unforeseen construction step!

Looking forward to seeing your scratchbuilt Atlas, Jay! Will you be doing it in 1:72?

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Great start! Nice to see some of these private corporation space craft hitting the market. The good thing about private ventures is the likelihood for very diverse approaches to design should be more prevalent. And yes, as long as they are being used in conjunction with or in service of NASA then they qualify. Space Ship 1 I don't believe qualifies though since it's a complete commercial venture.

Keep it up, can't wait to see more of this cool looking little craft.

Bill

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23sivbb.jpg

Another difference I've noticed between the HL-20 and the Dream Chaser is the shape of the nose. Dream Chaser has kind of a pug nose, while the HL-20 is more shuttle-esque. Should I try to reflect this shape by adding Milliput or just leave it alone?

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Should I try to reflect this shape by adding Milliput or just leave it alone?

Six of one and a half dozen of the other ... if you wanna make it look like the DreamChaser, you'll need to go that extra, Milliput, mile.

I know nothing of this little vehicle, so to see it any which-way is a treat for me!

I think I know which way you're leaning tho'. ;)

Pete

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I've been analyzing the Dreamchaser shape myself and the issue isn't necessarily with the nose (or at least not the bottom of the nose) but rather with the top area around the cockpit as the Dreamchaser pit is a little wider and sits a little further ahead than the HL-20 design. I was able to find a really good side image of the Dreamchaser windtunnel model and size it down to give me an idea of what to fix.

http://aero.tamu.edu/sites/default/files/images/news/snc_dc_windtunnel.jpg

I believe the image I got is a little higher resolution than this one, but it is the same image that I am referencing. I'll be using a combination of epoxy putty and sheet styrene to do the fix. There are some very subtle shape differences as well, but they are so tiny I'm not going to worry too much about going THAT far.

As for my Atlas V, yes it will be scratchbuilt. I am going to use Alfonso Moreno's 1/144 paper model Atlas as a template to make the bigger one.

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  • 2 weeks later...

DAYS 2-3

7.5 hours (11.8 hours total)

Build cost to date: $65.78

I spent most of the last 7-1/2 hours of this build trying to get the wings down to the correct size and shape. It's been quite frustrating trying to get them right! SNC hasn't released any drawings or measurements (that I know of), and requests for drawings have been ignored. There just aren't a lot of public resources out there on this bird yet, so there's going to be some guesswork involved trying to model this thing accurately here in the early-on. My first attempt at the wings were way too big, and I went through three different finished sets of wings before getting them down to something close to the proper size and shape. So here is one of the wings, with the flap scribed on:

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To anyone coming along behind me who builds this kit as a Dream Chaser, a quick way to get the wing shape in the ballpark from the start is to use the HL-20 kit wing as a guide and trace it onto your .080" sheet of styrene. Using your reference photos as a guide, modify the wing outline by sweeping the wings back several degrees to give them that swept-wing look, being sure to keep the edge that attaches to the body the same length as the kit. You will also want to keep the overall length of the wing itself the same length as the kit's wing. Again, until more accurate drawings and measurements are released, this is about the best we can do.

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Above, you can see where I sawed off the upright stabilizer on the kit resin with my Dremel and installed a more properly shaped swept fin, using reference photos as my only guide. The .080" styrene sheet was a perfect fit.

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In this picture, you see some putty applied to the seam below the fin, and work beginning on the OMS engines. I'm using the OMS nozzles from the 1:144 Airfix shuttle with some leftover beads from Mardi Gras. I used my drill to split the beads in half along the seam, and then sanded them down a bit so they would both be equally flush when glued to the aft bulkhead. I then soaked the beads in brake fluid for a half hour to get the metallic paint off, and then carefully drilled a hole in the center of each one for mounting the nozzles.

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Before gluing them together, I sanded the mouth of each OMS nozzle down a bit since they were a bit oversized for the Dream Chaser.

Here is a dry-fit of the engines in place on the bulkhead:

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In my next update, I hope to finish the bodywork, including milliputting the pug nose and drilling the RCS thruster holes in the correct locations. Maybe I'll finally get the wings on as well!

Edited by Hotdog
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  • 2 weeks later...

DAYS 4-5

4.5 hours (16.2 hours total)

Build cost to date: $65.78

I spent all of this time changing the nose of the HL-20 into a Dream Chaser. After all of this work, I feel like I could move to California and do nose jobs for a living! That is, if people wanted pug noses made out of Milliput...

Here is the nose before sanding to shape:

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And after about 2 hours of sanding, I pretty much got the new nose installed:

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With this done, I may finally be ready to glue the wings on. Then I'll probably go ahead and spray on the first coat of primer to check my work before drilling the thruster holes and scribing in a few details.

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All freehand, with foam sanding blocks and emery boards. Which is probably the reason why it took 2 hours. There were times where I wished I had some kind of small, handheld power sander of some kind. I am all ears if you know of any tools that might make sanding easier! It seems to be the part of model-making that I least enjoy. Currently all I have is a Dremel that has a few small sanding/grinding attachments, but none of those would have been suitable for this case.

Edited by Hotdog
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At this scale, sanding by hand offers you the utmost control. If you were building one at 1:1 then power tools fer sher ... but putting a piece of sandpaper over a wood block under a stream of water ensures you do it right the first time. I've tried using Dremels on these small models and it takes nothing to create a 'ding' which'll take another half hour to repair. Not to mention the dust these tools kick up.

Yeah, it took you 2 hours, but it was time well spent, it looks terrific and you don't hafta re-do anything. :thumbsup:

Pete

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You are right, Pete. Even with my extremely steady artists' hand, all it takes is one micro-misjudgement with that ornery Dremel and a small hole becomes a big dent in the body work. It can be very helpful at times, but like you said, at this scale, it would be overkill. I may not have had all the power I wanted doing it by hand, but I def had full control.

Edited by Hotdog
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DAYS 6-7

7 hours (23.2 hours total)

Build cost to date: $65.78

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I've gotten a lot done on this build in the last couple of days. I started by scribing the landing gear doors onto the belly. I traced the shapes using printouts of the doors I had drawn in Illustrator and cut out of paper. I applied Dymo tape around the areas to be scribed to help get the straight lines. White putty was used to cover up where I accidentally over-scribed.

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I also made sure to scribe the flaps into the aft bulkhead. While I was at it, I drilled a hole for inserting a rod that will help during painting. This hole will later be covered up by the hatch.

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Next it was time to break out the drill and get the thruster holes in the correct places. There were a couple that were slightly off and had to be filled in and re-drilled. At this small scale, you have to be damn near perfect hitting the drill bit in the right spot.

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With most of the body work pretty much done, it was time to get the wings on! Loctite Professional Super Glue worked excellent for this. The elevons on the top sides of the wings will be represented by decals.

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And this is how I've left her for now, with the wings puttied up where they meet the fuselage. The Dream Chaser is pretty much seamless where the wings attach, so smoothing this out without breaking the wings off will be a challenge. I'm using the Squadron Green instead of the Tamiya White putty for this since it seems to sand a bit easier. I've masked it off in the hopes of keeping the sanding down to a minimum to lessen the chances of breaking the wings off.

Edited by Hotdog
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This is looking great Hotdog!

If you DO break off those wings while sanding (I've too have found that resin to styrene butt-joints are fairly fragile), drill a couple of holes in the fuselage and wings and use styrene rod to reinforce the joint a bit.

Keep up the great work!

Pete

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Pete,

Great advice, as the original plan called for using thin metal rod (paper clip) to insert into the resin/styrene and reinforce the attachment of the wings. But the conversion into a Dream Chaser required the fabrication of my own wings out of .080" styrene and make them an airfoil shape. After doing this, the thickness of the wings was too thin to facilitate the thin metal paper clip rod as the reinforcement for the wing attachment. So all I was left with was to super-glue them. I suppose I'm just going to have to be careful with my sanding process.

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DAY 8

2 hours (25.2 hours total)

Build cost to date: $65.78

This will be a small update. While sanding the wings to blend them into the fuselage, I noticed on the real Dream Chaser that the leading edge of the wings also blend straight into the body. So, I broke out the Milliput again and fashioned them to extend all the way down.

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I'm going to let the Milliput cure overnight before I do any more sanding. I'll probably need to bust out the Squadron or Tamiya putty again to blend it all together. Just when you think you're getting close to being ready to paint...

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Can you guess what I'm going to use these grilling skewers for?

Since I can't use the RCS thrusters from the Tamiya Shuttle kit like I had planned (I forgot I already had them glued in), I had to come up with another way to represent the thrusters on the Dream Chaser. So, I'm cutting off the sharp ends of these babies and will use them instead.

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Here's a dry fit after drilling out mounting holes for the thrusters into the aft fuselage. I may need to sand them down just a tad bit more, but you get the idea.

Tomorrow, it's back to sanding on the wings. *sigh*. Ready to get past it and get some paint on this bird!

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Well, I'm glad to know you're not going to shishkebob the model! Great idea on the skewers. They really look the part. I have to say, I'm very impressed with what you're doing with what looked like simple kit. Your modifications are really coming out great!

Keep it up!

Bill

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  • 2 weeks later...

Have only just found this thread.

This is looking great Hotdog...the excellent mods you are making are working so well.

Just a thought re re- enforcing resin styrene joints. Dormer make a set of very fine drills all the way down to number 80 ( 0.35mm or 0.135inches ) and with fine brass wire ( rather than styrene rod ) such joints strengthen up very well. When pinning/re-enforcing 10 or 20 thou styrene joints just cut a slot to receive the wire then 5 thou styrene on each side and when cured overnight file back. If this is a 'teaching to suck eggs' situation my apologies.

Thanks for posting .....

Cheers

John

Edited by johnbuck
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Well, I'm glad to know you're not going to shishkebob the model! Great idea on the skewers. They really look the part. I have to say, I'm very impressed with what you're doing with what looked like simple kit. Your modifications are really coming out great!

Keep it up!

Bill

Thanks, Bill. Funny how "simple" I thought this build would be when I started, only to watch the list of required modifications grow as I went along! I guess there's really no such thing as a completely OOB build when you want to get things right.

Have only just found this thread.

This is looking great Hotdog...the excellent mods you are making are working so well.

Just a thought re re- enforcing resin styrene joints. Dormer make a set of very fine drills all the way down to number 80 ( 0.35mm or 0.135inches ) and with fine brass wire ( rather than styrene rod ) such joints strengthen up very well. When pinning/re-enforcing 10 or 20 thou styrene joints just cut a slot to receive the wire then 5 thou styrene on each side and when cured overnight file back. If this is a 'teaching to suck eggs' situation my apologies.

Thanks for posting .....

Cheers

John

That sounds like the ideal solution for anyone coming along behind me and building a Dream Chaser at this small scale. Luckily, I've got most of the sanding around the wing joints done now, and with all the elbow grease used in the sanding process, the wings have stayed firmly in place without the slightest budge or crack. Mad props to the Loctite Professional Grade super glue!

I hope to have a new update to show the latest progress in the next couple of days.

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  • 3 weeks later...

DAYS 9-11

6.8 hours (32 hours total)

Build cost to date: $65.78

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In my last update, I was using putty to blend the wings into the body. I spent most of the last 3 days going back-and-forth with the putty and sandpaper trying to get this right. The areas between the wings and the stabilizer are tight areas, too small for my foam sanding blocks, and I couldn't get too heavy with the elbow grease out of fear of snapping off the wings. This slowed things down quite a bit. Future Dream Chaser modelers, get your wings right before gluing on the stabilizer so you have more room to work!

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In this pic, we have a 1/2" disc made of .010" styrene sheet, a homemade decal, and two staples, shown next to a Quarter for scale. Can ya guess what I'm going to make with these?

If you said a rear hatch for a Dream Chaser, you are correct!

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This little project was a much needed distraction from all of the sanding and puttying I was getting bogged down in. Ah, but the fun was not over! A few more hours of puttying, sanding and smoothing was needed to get her looking flight-worthy.

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By this time, I had reached my end with all the body work. It was time to get some paint on this bird! After rescribing some of the details that had been smoothed over in the sanding process, I gave her a final sand-down with some fine sandpaper, and a good Windex bath. Finally, after two coats of Tamiya White Primer, this is what she looks like:

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As you can see in the photos, my puttying and sanding days are not over. There's still some rough spots to smooth out, some seams that need more filling, and some lines that need deeper scribing. :hangingsmiley:

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Hello Hotdog,

no reason to hang yourself, head high, you can cope also. :bandhead2:

You work very carefully, I like that. But sorry, with your decal of the rear hatch you have made a small mistake. :rolleyes:

The original has 10 struts, but your hatch has 12, which you should still correct, okay? :coolio:

BTW, it would look even better if you could scratchbuild these struts and the ring from Evergreen strips, that would be perfect. :salute:

:wave:

Edited by spaceman
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