Project XR2 Ravenstar - Mk II

[Coolhand]

I said "to make it look easier"... rather than clambering up and down a ladder, but you won't need it to actually get in and out, if i build such a thing at all, if that would even work.

 

[yagni01]

Just for fun really, it's nothing more than the port from the front copied, and wrapped in a tube. I don't know if it would work in the sim as a usable thing. would be neat for practising shuttle style docking though.

Sure it would. Shuttle has it of course, but more importantly, the XR-5 has it. Docking view and control mode already written. I like the dorsal port better than the nose, and you could have a ventral hatch for ground access like some bombers rather than climbing a ladder then crouching or crawling on hands and knees through the airlock into the cabin. So undignified.

Use the same airlock with an upper and lower hatch, and you never have to depress the cabin.

 

[yagni01]

http://www.scifi-meshes.com/coolhand/pics/deltaglider/glider_wip_95.jpg

Looking at this picture, are you thinking of moving the radiators to the payload bay doors? I think the radiators should be much larger than the small ones between the tails. They wouldn't be very efficient, either, being bracketed by their hatch covers. You could use the whole top of the ship from cabin to tail by moving the consumables hatches outboard some. With radiators on both the ship and the doors from the payload bay back. Lots of nice cooling.

Also, the door forward of the dorsal docking port - is that a hatch directly into the cabin? Or a Ku-band antenna?

 

[Coolhand]

Sure it would. Shuttle has it of course, but more importantly, the XR-5 has it. Docking view and control mode already written. I like the dorsal port better than the nose, and you could have a ventral hatch for ground access like some bombers rather than climbing a ladder then crouching or crawling on hands and knees through the airlock into the cabin. So undignified.

Use the same airlock with an upper and lower hatch, and you never have to depress the cabin.

the airlock from the front is also copied to the bay, there's room for the complete assembly in the bay, i tested the size with that and made sure it would fit because thats the deepest thing that might end up in there. it can also connect to the passenger cabin because theres a pressure door in the cabin that would connect to the airlock.

When i said whether it would work, I just mean how it would work in terms of coding it, particularly if it's modular and user configurable. and there's no need to cart 2 airlocks and docks into space unless you're training for something, so if it can go in as an configurable extra it will, otherwise you'll only have the option of the front dock.

A ventral hatch had been discussed in the old thread... I'd maybe do it if your astronaut could actually walk up it. Also it would have to work in other low pressure environments, which would mean it'd have to come from the front airlock, and thats surely lots of hassle & not terribly practical. Besides, you still need to crawl out through an airlock when you get to the station or another ship so if you're a passenger you might as well get used to it on the ground... stupid ground hogs..

 

[Coolhand]

Looking at this picture, are you thinking of moving the radiators to the payload bay doors? I think the radiators should be much larger than the small ones between the tails. They wouldn't be very efficient, either, being bracketed by their hatch covers. You could use the whole top of the ship from cabin to tail by moving the consumables hatches outboard some. With radiators on both the ship and the doors from the payload bay back. Lots of nice cooling.

Also, the door forward of the dorsal docking port - is that a hatch directly into the cabin? Or a Ku-band antenna?

I've been waiting for this comment for ages... the design i'd originally planned for the radiators didn't work or look as good as i'd liked so it ended up with a more simple mechanism. Its true they wouldn't be so efficient since they actually radiate back onto the ship somewhat though they are proportionally much larger and tougher looking than the DG and XR1 radiators.

The antenna/hatch is the upper hatch, i hadn't considered that it might look like an antenna, it has a sliding inner hatch underneath.

 

[TSPenguin]

I've been waiting for this comment for ages... the design i'd originally planned for the radiators didn't work or look as good as i'd liked so it ended up with a more simple mechanism. Its true they wouldn't be so efficient since they actually radiate back onto the ship somewhat though they are proportionally much larger and tougher looking than the DG and XR1 radiators.

I can't imagine any configuration that is cooler looking than this.
What if they stayed in this spot but opened to the back. (So that it radiates towards the back)
If it comes out and deflates it might nearly reach the height of the wings. If the markings on the hull are more than just a border around it it might actualy look kinda mean. And dutchpirate would have a nice spot to place each Furry Dice!

Front view:

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[martins]

I just had a look through the images of the XR2, and it looks truely amazing.:hotcool:

I have just one technical concern: looking for example at http://www.scifi-meshes.com/coolhand/pics/deltaglider/glider_wip_53.jpg, it seems that the main gear is set extremely far back. Assuming that the XR2 is intended for runway takeoffs and not just landings, this could cause severe problems. The main gear defines the rotation point during takeoff, and the further behind the centre of gravity it is located, the more force you need to lift the nose. Furthermore, the force for lifting the nose during takeoff is mainly generated by the down-force of the elevators on the aft of the fuselage. There is very little distance between the main gear and the elevators, so the effective lever is very short. The elevators would need to generate massive down-force, which might either rip them off, or collapse the gear before managing to lift the nose.

Sorry for coming late into the discussion - I don't know if this has been mentioned before, or if the screenshot is still up to date. But if the design is still flexible, it might be worth keeping in mind (maybe for an XR2.1?) This is of course just a (hopefully constructive) suggestion. Feel free to ignore - it's your design.

 

[TSPenguin]

This concern hasn't been raised before. Amazing when you think about how "obvious" it is.

Having some extendable winglets somewhere on the nose would be great, but where fit them? (more important: how?)

 

[yagni01]

This concern hasn't been raised before. Amazing when you think about how "obvious" it is.

I also just noticed the gear may be too short to get a decent alpha at T/O. Tail skid.

 

[Donamy]

You could extend the nose gear for a higher AOA. also vectored thrust.

 

[martins]

Having some extendable winglets somewhere on the nose would be great, but where fit them? (more important: how?)

Winglets on the nose would provide a better lever, but I don't think that they could generate sufficient force if the gear is located so far back. They would essentially have to lift the entire aircraft.

Another possibility might be to have a very high nose gear, so that the aircraft already has a high AOA as it rolls down the runway. This way, it might generate sufficient lift for takeoff without a pronounced rotation. I don't know if this is feasible - maybe somebody with engineering experience in this field could comment?

Edit: Donamy beat me to it

 

[Donamy]

Another possibility would be a ramp.

 

[dutchpirate]

You could extend the nose gear for a higher AOA. also vectored thrust.

"Realism" might be against anything that projects the thrust downwards onto the runway surface for extended period due to heat damage to the runway.

There are several modern-day aircraft with very low ground clearances that use very little initial rotation to get airborne. The gear is still located more centrally on the airframe, but they have very flat initial climb outs. The Mitsubishi MU2 is the first example I can think of.

Flaps or leading edge slats might be another consideration if you want to boost the amount of lift being generated at lower airspeeds so you don't have to rotate as much.

 

[Coolhand]

I do want it to look like it can takeoff conventionally, without the need for ramps, extra wings or extra fuel expenditure. Perhaps it still could in real life with a shallow takeoff angle like Dutchpirate has suggested, and perhaps if i angled the nose up a bit by making the front gear slightly extendable as has also been suggested by Martin and Donamy.

It's inelegant, but what about the RCS - could they be used to help lift the nose?

i think maybe one other factor that would it get off the ground is the low delta wing, i'm clearly no aerospace engineer but wouldn't that also generate a lot of ground effect for its size? this would surely take more weight off the wheels and allow more of a pitch up.

 

[dutchpirate]

Ground effect is a lot of fun to fly in too! It's my favorite way to take off. It's commonly used for soft-field takeoffs where you need to get 'unstuck' from the ground quickly, but you remain in ground effect until your airspeed builds up enough for a safe climb out....or you stay in ground effect until you start pushing the yellow arc on your airspeed indicator then pull up hard!:speakcool:

Does ground effect exist in Orbiter? I've always just used the raw power of the mains to get in the air and start my climb.

 

[Urwumpe]

i think maybe one other factor that would it get off the ground is the low delta wing, i'm clearly no aerospace engineer but wouldn't that also generate a lot of ground effect for its size? this would surely take more weight off the wheels and allow more of a pitch up.

Yes, but the ground effect works better the closer and earlier you can move the trailing edge of the wings to the runway. Moving the landing gear a bit forward will be a good idea anyway for that. Also, you can use drag for much longer when you land, if you can keep the nose up and controlled for a while (like the space shuttle)

 

[Coolhand]

Well i may move them, I'll have a think about it, i hear ya about the nose up on landing thing. Martin has come up with a great crit in the design, I'm surprised no one's mentioned it before! There's always been something about the gear that didn't quite look right, but i couldn't quite put my finger on it, I've been more concerned about the maximum AOA on takeoff/landing, which is mostly why they ended up so far back.

 

[Urwumpe]

I've been more concerned about the maximum AOA on takeoff/landing, which is mostly why they ended up so far back.

Believe me, I have done the same before the first take off run in Orbiter had told me "Oooops!".

It makes perfectly sense when you visualize the lever arms, but it is unexpected before you do that.

For my still unreleased Starstreak add-on (which I use for testing almost any crazy thought I can get), I also have the main landing gear very far back, but the wedge shape of the lifting body and the strong torques by the air brakes on the top surface makes it still easy enough to keep the nose up. When the drag chute would get implemented, this would even keep the nose up at ~10° pitch automatically.

 

[Coolhand]

ok, well here's a revised version. i was able to retain the main part of the wheel well and move the little annexe that the strut retracts into from aft to forwards of the main part... essentially just mirroring the well or reversing it. obviously the gear needs to be extended to maintain the AOA but it seems to accomodate this. most the main gear assembly will need to be rebuilt and retextured but i've been able to make the changes with minimal changes to the geometry of the model.

the grey circle indicates the wheels previous down postion, it's a fair bit further forwards now.

 

[dutchpirate]

Nice work Coolhand! Looks better.

I was just showing a co-worker the size difference between the XR-1 and XR-5. He made an interesting comment. The XR-1 looks like it might almost fit in the bay of the -5, if only it had folding wings!!:speakcool: