HyperDart - A new spaceplane

[clickypens]

Awesome! I'm glad this came out Friday, so I can spend the whole weekend trying it out. I can't wait to unzip it. Keep up the great work.

 

[tgep]

I've downloaded the latest public beta for testing. I'll post a report here If I have any troubles.

 

[Usquanigo]

Some of the VC displays are hard to read, actually the VCs are a usability nightmare, but it will require a major rework of the models to make them better. That will be something for a later date.

I disagree. I love the VCs, and the fact that that is how they are controlled (like SSU). Some switches are a bit hidden, but they are all as yet unusuable/decorative.

At most I would suggest enlarging the touch panel display in the XL, and separating the 2 vessels in terms of HUD and MFDs (if it's possible) and removing the orbital HUD button from the XL's cockpit. (and I don't know if it's possible, but eliminating it from the H key cycle sequence would be aweseome too - but that might be something stuck deep in the orbiter core)

Do you have plans to do anything with the computer interfaces you've added? Just curious.

Oh, the cockpit forward of the dash on the XL (what would be the upper dashpad on a car, as well as interior of the a-pillars) is VERY dark. Would it be possible to lighten that up a bit so the contrast isn't so steep?

I'm especially interested in how you launch the Dart, what type of profile you flew, and feedback on reentry with the Dart. Remember, the entire package is supposed to be a semi-realistic design based off updating 1950-60 technology demonstrators. This isn't a Delta Glider or XR series craft, more like the space shuttle in capabilities.

Might be a little high in that case then. But still a mega cool addon all around. (and you know I'm lovin' the XL especially :speakcool: )

 

[tgep]

While testing the XL-70, i had a gear mechinism failure at pitch up during take-off. I'm wondering if it's because I have the NoseWheel turn plug-in running ?

 

[CigDriver]

The gear will fail based on dynamic pressure. I always pull them up as soon as I establish positive climb. I've not used the nosewheel plug-in, so it could be related to that too.

speaking of which, I wanted to put that code in for both craft. I'll have to go look up the thread.

 

[tgep]

I set my trim to +3 for takeoff and rotate betweem 165 and 185 ..... It happens every time I try. I use full power at take off then throttle back to 75% for pitch and climb and turning.

 

[Usquanigo]

It's just a matter of getting the touch. Beleive me.

You don't need full throttle for take off, btw. Like CigD said, it's got so much power (power that is NEEDED for the alt and speed it shoots for) that in the lower atmosphere it can really damage itself (not un-like the XR-2 actually).

I have, on many occasions used roughly 50% power for take off. Sometimes spike the engines to 100 just to get rolling, then throttle back. It rolls past 100m/s easile even with less throttle than that (and a loaded HD strapped to it's back). Once you hit 100 m/s, start to rotate, once up, pull the gear up ASAP, and start a climbing turn toward your desired heading, keep speed from falling or climbing, can be in the 150 to 160 range. After a minute or so the gear should be up and you can start to open it up, then just use pitch to control speed (try not to go over 30* or so, I'm sure it can handle more, I just doubt it would outside of Orbiter, plus, you do want to slowly increase your speed, you get better climb rate with more air speed).

Once you hit anywhere from 10 to 20Km, level out, and let the speed build, using pitch for a shallow climb to control Dynamic Pressure.

I take it to as near 40Km as I can get, ~35 to 37, level out, build as much speed as I can, then shallow dive down to about 25 and release the Dart. VERY tricky area of the envelope though, must be VERY careful. Once the warning lights come on, it's already too late (you'll never correct in time without over-G'ing it and breaking something anyway).

In that regime, the Dart floats off and is on it's merry way nice and easy.

Might take a bit of practice, but keep a gentle touch at take off, remember that at that altitude it's seriously "overpowered".

 

[Tommy]

I'll put in a vote for redoing the switches in the VC. The ones on the left (engine, RCS and Aero selectors) are next to impossible to see where they are pointing. They are also quite hard to click (could the bounding box or whatever be enlarged - same for the COG and trim controls).

Gear and Airbrake status lights might be handy in the XL-70 - those controls are out of view normally and many of us use the keyboard or JS switches to activate these. If you'll be including custom sounds for this later that would help provide some feedback on the controls.

As for re-entry, it seems a bit too heat sensitive. I understand that this isn't sheilded heavily like the shttle or XR vessels, but it seemed pretty touchy for an orbital vessel, at least down to around 5.5 km/s. Also, there doesn't seem to be as much drag at higher AoA's as I would expect, but that could just be because you have to keep it so high - but there didn't seem to be much difference between decelleration at 50 degrees or 5 degrees.

COG shifting and trim work wonderfully to maintain AoA - I was even able to use some 10x time accel during re-entry from about 6.5 km/s to 2.5 km/s. On this old box, only the TX lifter has been as stable!

BTW, is there an airbrake for the HD?

 

[halcyon]

Also trying it out, and also want to know if there's an air brake.

 

[CigDriver]

There isn't currently an airbrake on the HyperDart. The XL does have one, but it is keyboard only, B if memory serves me right. I'll add one to the Dart, that isn't too hard. I'll also bump up the heat tolerance of the Dart a bit. Technically I'll change the heat transfer rate for it. Even though there isn't numbers shown on the displays (no room!) the heat is calculated in real numbers. If I remember right I have the max heat for the Dart set at 1250K, and I do not really want to raise that.

I'd love to rework the cockpits at some point. It is just a bit more work than I want to get into at this point. I'd rather just use the ergonomics of the cockpits as learning lessons for my next add-on.

From what I understand orbiter calculates the drag based on the lifting surfaces. I'm not sure how much I can change it without messing up the flight model. I'll look into it though. Of course the dart is a super slick low-drag design

 

[Usquanigo]

I'd love to rework the cockpits at some point. It is just a bit more work than I want to get into at this point. I'd rather just use the ergonomics of the cockpits as learning lessons for my next add-on.

I think the switch issue could be a simple matter of coloring. They seem to be layed out in a very ergonomic fashion, and I can't see a better place to put them, nor a way to enlarge them.

But if they were a more contrasting color combo (yet one that matched the overall pit), it would make it easier to tell what's what.

Another option might be smaller versions of the buttons used for the HUD and AP.

I too think that enlarging the touch panel would be beneficial as well. It's not super important, but would be nice (in both).

Finally, lightening the dash ahead of the panel in the XL would give it a more realistic feel IMO. But again, a minor issue.

From what I understand orbiter calculates the drag based on the lifting surfaces. I'm not sure how much I can change it without messing up the flight model. I'll look into it though. Of course the dart is a super slick low-drag design

So it doesn't count body drag at high AoA? Intersting.... bit of a bummer too. Is there any way to fudge it? Something like for a certain AoA artificially add drag? Or maybe AoA plus Alt. Or something like that? (might not be possible, just tossing out ideas )

I agree that messing up the FM would not be a good option. (though bringing down ISP a bit isn't too bad hehe... )

 

[CigDriver]

Both the dart and the XL do have wings to represent the body. Most of the lift of the dart is from the fuselage actually, it is a lifting body after all I'll look through the code and check exactly how the drag is calculated and see what i can do. I ported most of it over from the DG, adjusting the obvious things like aspect ratio and chord. I also tweaked the parts that control lift vs AoA to better represent a lifting body's attitude.

I'll fix the dash lighting on the XL too. The lighting in the textures was rendered with max and placed onto the base textures based on lights in the cabin, so the far reaches of the nose are too dark. I also think it would be pretty easy to update the rotary knobs with a new color. I'll have to dig back into my textures and mapping, but i think they all use the same texture or area of one texture. I'll lighten them up a bit so they are easier to read.

Another issue with the VC is I use freetrack. I run with a pretty tight zoom setting and just look around as needed. When I'm on my laptop I just know where everything is so it isn't an issue. I'll keep that in mind next time I build a VC.

I thought the XL had a gear indicator on the HUD, I know the Dart does. It is just like the DG, three boxes appear when the gear is down and flash if it is moving. If it is missing from the XL I'll put it in there. I'll also add text notifications to both HUDs for the speedbrake.

 

[Usquanigo]

I think you did a spectacular job on both the VCs. The layout in each looks cool, makes sense, and feels real.

I tend to run at 60* FOV in the XL, and that lets me see the gear lever, even though I use the KB button to trigger it, and I can see both MFDs and the full HUD very clearly, as well as seeing the touch panel, having access to the CoG and trim, and also watching the sliders for the temp and DynP, it works great.

I also run at 60 in the HD as well, but at that FOV it's hard to read the sliders on the touch panel, and also the test on the buttons (AP and HUD controls). However, that last point is ok, a trained pilot of that craft should know which button does what without having to use or read a label.

But in both cases, the only thing I would say to do differently would be a large touch panel that is easier to read from an FOV of 60 (or more). Not something that over-rides and dominates the pit, but just something nice and readable while also being far enough back to take in everything else.

BUT.... that said, I think they are great just as they are too.

 

[Tommy]

For the knobs, just adding a white line on the top would be fine, and easily visible. I like the layout in general, the main complaint I had was the small size of the clickable area for the controls, and I have no idea how hard is would be to re-do the bounding boxes (or whatever Orbiter uses - never looked into building a VC yet).

As for the heating, my re-entry profile could stand to be improved some for this vessel also. Last attempt (from 375km orbit) I de-orbited when I passed over Wideawake, set the PeA at 70k. When down about 125k rolled 90 degrees (right, since that was the direction I needed to go) then upped the AoA to 40 degrees. Down around 85k I rolled out to about 45 degrees for a bit to slow the descent rate. When the descent stabilized at about 80k alt, I maintained a 10 to 15 m/s descent rate using roll to adjust the VACC (was slightly inverted for a bit unti speed reduced below 7.5km/s).

By the time I was down to 4.5km/s and 60k alt, I knew for sure I was short, so I reduced the AoA to get Airbrake on target. At the lower velocity the HD was able to withstand the "bouncy" trajectory a fixed AoA provides. Bled off a bit to much speed before final, and hit the ground at about -10m/s VS, 80 m/s GS, and 150 meters short of the runway. That's where the airbrake will help, since I can maintain a safety margin and bleed it off closer to touchdown. Until then I'll plan a powered final approach.

Again, kudos on two very flyable craft. With the fine adjustments available for the COG, you can trim out both vessels to where they pretty much fly themselves even without Aerobrake's Altitude AP. In fact, with this old PC, they are more stable without it, especially at 10x time accel (I'm only getting about 10 FPS with the VC active, but these craft are flyable even at that low framerate!).

 

[halcyon]

Question to everyone: what are you using for attitude autopilot to hold a specific AoA?

 

[Tommy]

I use COG shifting to maintain desired AoA - shift it back (down on the display) to increase AoA. It will "bounce", especially for large changes (killrot can be used to dampen the oscillations) but will quickly settle and hold constant. No AP is needed. You'll need to trim out starting about 95k to 100k alt, above that there's not enough air.

The Elevator trim doesn't do much at a high AoA, but the COG can be tuned in very small increments and allow pretty much one degree "resolution", so it's fine. At lower AoA's a combination of COG and elevator trim can be used very effectively.

 

[halcyon]

Thanks for that Tommy, will give it a try.

---------- Post added 09-12-2009 at 12:36 PM ---------- Previous post was 09-11-2009 at 09:31 PM ----------

To CigDriver: in regards to the minilander, you mentioned earlier that it attaches to the HD through the scenario file, but how do you re dock after jettisoning?
There's only one docking port on the HD as far as I can tell. Is the lander just a write off after that?

Also, do you plan on:
- putting in a refueling option from both the ground and orbiting stations?
- including a radiator?
- including a retro thruster that uses fuel from the OMS engines? braking is hard to do with only the transition RCS thrusters

With those questions out of the way, here's my feedback thusfar.
I've tried several different launches on different headings. I've docked with ISS, and then I tried a couple different reentries.
My findings:

- even when launching on a due east 90 degree heading, taking maximum advantage of the earth's rotation to achieve orbit, I'm still burning all my main fuel before I can raise my PeA above at least 120km. I'm sure it's possible as someone said to leave 6% of main fuel, but the margin for error is so small I'd like to see a tad more fuel put in the main tank

- docking is standard reversed controls such as the orbiter. No issue there

- reentry I had some issues with. Held an AoA at 40 degrees starting with 120km in altitude and about -70 m/s VS. By the time I had reached 80km, my underside heat temp was redline already, with nose and wing halfway up the scale.
The bird is heating up too quickly. I shouldn't be redline before I even hit 70km at a -70 m/s descent rate, as there isn't enough atmosphere PSI to produce that much friction. Even when my VS lowered to -40 m/s I was still in the redline on temps.

 

[Usquanigo]

Also, do you plan on:
- including a radiator?

What for?

- including a retro thruster that uses fuel from the OMS engines? braking is hard to do with only the transition RCS thrusters

That's what the Retrograde AP and the docking HUD displays are for.

- even when launching on a due east 90 degree heading, taking maximum advantage of the earth's rotation to achieve orbit, I'm still burning all my main fuel before I can raise my PeA above at least 120km. I'm sure it's possible as someone said to leave 6% of main fuel, but the margin for error is so small I'd like to see a tad more fuel put in the main tank

It should NOT be possible at ALL to get into orbit from the ground in the HD alone. If it can, that would suggest the ISP is probably a bit too high for the previously stated goal of near future realism.

You have to use the XL-70, take it to over M3.6 at 25Km alt, then launch the HD and head into Orbit. You can easily (too easily?) reach an orbit well into the 400s.

- reentry I had some issues with. Held an AoA at 40 degrees starting with 120km in altitude and about -70 m/s VS. By the time I had reached 80km, my underside heat temp was redline already, with nose and wing halfway up the scale.

The bird is heating up too quickly. I shouldn't be redline before I even hit 70km at a -70 m/s descent rate, as there isn't enough atmosphere PSI to produce that much friction. Even when my VS lowered to -40 m/s I was still in the redline on temps.

Based on what research and data?

I don't mean to be a smart-ass, but honestly, statements like that beg that counter-question. It IS a challenge, and that's kinda the point. CigDriver has already said that he doesn't want to increase the overall temp threshold (and I agree with him), but that he will work on tweaking the heat build rate, slowing it down a bit, and also adding an air-brake.

You can't come crashing down like a capsule or a space shuttle, you have to fly it down, gently, slowly, keeping heat as low as possible.

Bear in mind just how difficult it is to get into space in the first place, in order to even keep this reasonably plausible it would have to be as light as possible and sacrifice somewhere, arguably, that would be in heat shielding, but that's not a problem, it works, it's just a matter of the pilots adjusting to the new methods and techniques required to make it work.


CigDriver - I don't mean to speak for you or put words in your mouth, I hope it doesn't come off that I was. Just relating some of the info I've picked up from you here, hopefully to safe you some time.

 

[T.Neo]

What for?

Cooling electrical and environmental systems. Such a feature would greatly add to realism.

 

[Usquanigo]

Cooling electrical and environmental systems. Such a feature would greatly add to realism.

You missed the point.

That assumes that such cooling is actually necessary, it may not be. Who's to say unless they actually get into designing it.

If such a thing WERE added, it would probably require a model tweak (though could be as easy as coding it to the inside of the bay doors, thus not needing any changes), but would *definitely* require yet another code piece to calculate internal heat build up and cool down rate.

It's not a bad thing (might even be cool). I'm just saying the automatic assumption that it's needed, or that it would inherently add realism isn't correct (as it may be using alternate tech to avoid or deal with those problems).