SSTO engines

[crestofawave]

hey guys, been looking through the ssto thread and I haven’t played long so can’t identify what seems to be the most common engine, it seems to have blue intakes?

also what mod would you suggest to build a good ssto, stock/fasa/ knw / i intend to build one for stations and the mun,

thanks for your help

Edited September 4, 2015 by crestofawave

[legoclone09]

You need to look at new SSTOs, the blue intakes are Ram Air Intakes, those are what people used for air hogging, it was an exploit used to power jets all the way to space. I would look around in the Spacecraft Exchange for some, lots of amazing ones there. This has some nice SSTOs for LKO on it (http://forum.kerbalspaceprogram.com/threads/132671-What-craft-do-you-use-to-retrieve-Kerbals-from-space)

[crestofawave]

aha, im only a way through the thread, i guess the engines will change nearer the end, got a good design runing rappiers but now need to sort the orbit/mun ones

[Fearless Son]

Yeah, the aerodynamic changes in 1.0 have rendered a lot of the old spaceplane information obsolete. If you see blue intakes, that is a sure sign it is an older design and I would not trust it to work in the newer version without serious vetting.

That having been said, there are many different engines that can be used for spaceplanes, but you will rarely find a spaceplane that only uses one type of engine. Most use at least two types of engine, some use three. The reason for this is that different engines are optimal in different conditions, and spaceplanes go through a lot of different conditions.

Let us go over a bit of a list, shall we?

- Wheesley: Small jet engine, optimal at high atmospheric pressure and low speed, very fuel-efficient. Good for small planes and things that need to fly slowly, but rarely used in spaceplanes.

- Whiplash: Turbojet engine, optimal at low atmospheric pressure and high speed, liquid-fuel gas guzzler. Most spaceplanes use this engine as part of their design because it is ideal for building up speed while still in the atmosphere, and thanks it to being a jet instead of a rocket, even as liquid-fuel hungry as it is, it is still much more efficient than virtually any rocket. They might take a little effort to get off the ground, but are great once you are above 10K.

- R.A.I.P.I.E.R.: Hybrid jet/rocket engine, generally less powerful than the Whiplash, but also capable of running at altitudes that would cause the Whiplash to flame out, can switch to rocket mode to take it up into space. A popular option for ecking that last little bit of speed out of your atmospheric-breathing flight, but usually not powerful enough to get most spaceplanes to the threshold where they become ideal. Also only moderately efficient for their thrust as rocket engines, so you cannot expect to go past Low Kerbin Orbit if these are your primary spaceflight engines. Requires oxidizer to burn in rocket mode, so you have to bring some to use them.

- LV-N Nerv: Nuclear thermal engine, only burns liquid fuel, heavy but very efficient, poor thrust. An option on some spaceplanes, and a popular option for the final stages of rockets as well. It has its drawbacks (the poor thrust, large size, heavy weight) but also its advantages (can go far, potentially simplifies the craft design if you have no other oxidizer burning engines you need to make fuel for which makes all your reaction mass usable in all conditions.)

-Other LV series: Liquid fuel and oxidizer burning rocket engines, only activated at high altitude for your final push to orbit. The LV-45 is sometimes used as it is low in the tech tree so it is accessible, reasonably good mix of thrust and efficiency, and is not too heavy. Other options usually replace it as they get unlocked though.

-Aerospike Engine: Liquid fuel and oxidizer burning rocket engine, virtually unaffected by atmospheric pressure, small, and with reasonably good efficiency and thrust. Another popular engine for spaceplanes, again used only for that last push to orbit after the jets have done all they can. Exploits aside, it does not stage with other things behind it, but since an SSTO by definition does not have more than one stage that is not a design concern here.

Again, most spaceplanes will have a mix of more than one of these engine types, usually jets followed by rockets. The R.A.I.P.I.E.R. can pull double-duty there, but is not quite as good at either task as more dedicated engines, but can still be useful for certain kinds of craft depending on their flight characteristics. They are also the only type of engine that a spaceplane can realistically use without any other engine type complicating the design.

[crestofawave]

thanks for that Fearless, hehe i didn’t realise the rapiers were switching, till the other day, if you forget to right click on everything you don’t see all the options or sometimes even know what they are.

my rapiers can get me into LKO ok, i need to now work on my design and engine config for vacuum use

[Val]

aha, im only a way through the thread, i guess the engines will change nearer the end, got a good design runing rappiers but now need to sort the orbit/mun ones

Much of the information and many (most?) of the stock designs made prior to the current KSP version (1.0.4) are probably obsolete. So jump ahead in the thread to posts after 23 June 2015.

- - - Updated - - -

- R.A.I.P.I.E.R.: Hybrid jet/rocket engine, generally less powerful than the Whiplash. ...

I don't agree with this assessment. I think the Rapier is much more powerful than the Whiplash.

While it is true that it has low sea-level thrust, making take-off and acceleration up to mach 1 a little harder. In all other regimes it is much better. Higher thrust at a higher top-speed, to much higher altitude.

[Pecan]

I wouldn't recommend any part-mods for making SSTOs unless you just like the look of the stuff they give you.

Essential mods for designing anything are MJ or KER for all the stats that KSP doesn't show you.

All my early SSTOs use the T-45 engine, with the appropriate launch engine taking over as the builds get bigger.

For spaceplanes I almost exclusively use the rapier and, of course, don't go flying them through space or to other planets and moons.

Engines and intakes are different parts - it's safe to assume any air-breathing engines you see on spacecraft are turbojets or rapiers. Non-airbreathing engines don't need intakes, of course.

[KerikBalm]

- R.A.I.P.I.E.R.: Hybrid jet/rocket engine, generally less powerful than the Whiplash, but also capable of running at altitudes that would cause the Whiplash to flame out,

Its less powerful at low speed, its more powerful at high speed.

It also has a higher maximum speed. It also "guzzles" more fuel than the whiplash (which I wouldn't call a gass guzzler either... 4000 Isp is great, just because the pre-1.0 turbojets could get 40,000 Isp doesn't mean that a 4000 Isp engine is a gas guzzler)

-Aerospike Engine: Liquid fuel and oxidizer burning rocket engine, virtually unaffected by atmospheric pressure, small

That shoulds like a pre-1.0 summary. It is very much affected by atmospheric pressure.Its Isp is about 230 at Eve sea level, its Vacuum Isp is 340.

Losing ~32% of your thrust because of atmospheric pressure is not "virtually unaffected"

Even on Kerbin, it loses ~15% of its thrust.

Pre-1.0, its Isp varied between 388 and 390 (and I think Isp didn't decrease as atmospheric pressure exceeded 1 atm, as on Jool and Eve).

Now it performs close to ideal for each atmospheric pressure.

Looking for a vacuum engine? The aerospike gets 340 while the LV-909 gets 345, and the poodle gets 350 meanwhile the aerospike beats the crud out of these engines at 1 atmosphere (290 vs 85 and 90 Isp)

Looking for an engine at 1 atm? the aerospike gets 290, while the mammoth gets 295, meanwhile, the aerospike beats the mammoth once in space... 340 vs 315

Looking for an engine at 5 atm? there is no bell nozzle in the game optimized for performance there, the aerospike wins handily.

[Fearless Son]

Alright, alright, the R.A.I.P.I.E.R. is very powerful within the constraints of its performance envelope, and yes, that description could apply to any jet engine. However, that envelope is quite narrow, being very high and very fast, and its performance is quite less than the Whiplash lower and slower than that. I was trying to communicate that in a quick summery, and maybe I stumbled on that bit. What I wanted to get across is that it is rarely used as a primary lifting engine to get off the ground and into its own ideal envelope. You could say similar things about the Whiplash, but it usually has enough power below its ideal envelope to serve in that capacity that adding Wheesleys would be a bad tradeoff for the additional mass they would bring.

As for the aerospike, yeah, I admit most of my experience with it is pre-1.0. Still one of the better rocket engines at high pressure, just no longer perfect. I do recall people saying that it is a fairly good space engine now though, comparing thrust and efficiency to other rockets for its size and mass, which still makes it a decent spaceplane rocket engine.

[Fearless Son]

hey guys, been looking through the ssto thread and I haven’t played long so can’t identify what seems to be the most common engine, it seems to have blue intakes?

Also, I wanted to address the intake thing.

First of all, older designs tended to require huge numbers of intakes to catch as much air as possible on their ascent. Sometimes people would make a tightly fitted "stack" of air intakes to get lots of intakes worth of air in only one intake's worth of space. This technique, known as "air hogging", is no longer necessary or beneficial in the new aerodynamic system after the 1.0 version, so do not try it here or you just make the spaceplane more difficult for no additional gain. That having been said, the new aerodynamic model makes it so that a few intakes can power all your jet engines. The faster you go, the more air they catch, so there is no benefit for having an unbalanced number of intakes. In this regard, there is some difference between intake types as far as efficiency goes.

Another list:

-Circular Intake: Regular jet intake, works best at high pressure and low speed. If you have an aircraft that needs to fly slowly, this intake will insure the jets have plenty of air to breath even if it has to hover. Ideal compliment to the Wheesley engine.

-Ram Air Intake: Hypersonic jet intake, works best at low pressure and high speed. It becomes more efficient at pulling in air the faster and higher your plane goes, making it a good choice for spaceplanes. More massive than the Circular Intake, so it works against you if you are going for low speed flight. Ideal compliment to the Whiplash engine.

-Shock Cone Intake: Hypersonic jet intake, works best at low pressure and high speed. Like the Ram Air Intake, but with more intake capacity and more mass. In fact, one of these has about twice the air intake capacity of the Circular Intake. Also has one of the lowest drag coefficients of any "cap" part. This makes it almost ideal for spaceplanes.

-Radial Intakes: Comes in "fat" and "streamlined" varieties. The former is good for lower speed applications where drag is less of a concern, the later is better for higher speed applications where its smaller cross section is less of an issue. In either case, you would need several of these to feed any of the engines. Enough of them can be used as a replacement for the "cap" style intakes in a pinch, but generally used as a supplement more than a primary source of air.

-Integrated Intakes: Some structural parts have intakes built into them, like the Engine Nacelle or the Engine Pre-cooler. These parts also generally have some liquid fuel capacity built into them as well. However, both their intake capacity and their liquid fuel capacity are fairly small. As such, they are rarely used as a primary source of either intake air or liquid fuel, but they are frequently used to supplement things that are already there. An oxidizer-burning spaceplane generally requires a bit more liquid fuel than its rocket fuel tanks will accommodate, and these are one way of getting that extra liquid fuel for the jets and supplementing the intake air at the same time without the excessive mass a dedicated liquid fuel tank might require.

In general, do not try to make a spaceplane with jets fed by circular intakes, they have too much drag at high speed compared to the amount of air they take in. A few ram air intakes will work and many designs use them, especially ones in the mid-range of the tech tree. Shock cone intakes are very popular for their great capacity and low drag, but the mass-to-intake-to-engine ratio can be a little more tricky to balance. Also, common wisdom holds that once the jets are completely offline you should toggle all your air intakes closed to shave off a little more drag, but last I heard the jury is still out on how effective this is in the new version.

Edited August 28, 2015 by Fearless Son

[Geschosskopf]

(the Aerospike) It is very much affected by atmospheric pressure.Its Isp is about 230 at Eve sea level, its Vacuum Isp is 340.

Losing ~32% of your thrust because of atmospheric pressure is not "virtually unaffected"

Even on Kerbin, it loses ~15% of its thrust

However, at Kerbin, when used as the rocket for a turbojet-powered SSTO, you'll only be running the Aerospike at altitudes of about 23km and above. That high up, you are above the bulk of Kerbin's atmosphere so the Isp is nearly at its vacuum value instead of its sealevel value. Actually, this is true for all rocket engines, not just the Aerospike. Even engines with pathetic sealevel Isps (Poodle, 909, LV-N) have nearly their vacuum Isps at 25km.

Also, I wanted to address the intake thing.

Something you didn't mention but I consider rather important...

The IntakeAir capacity of all intakes is completely meaningless. What really matters is intake area. This is because of how jet engines work. Each tick of time, the jet consumes some amount of LF and some amount of IntakeAir. If it lacks either one, then the engine will not run. To be able to grab and consume the resources, there must be tanks of them in the plane. The LF is in a fuel tank, the IntakeAir is inside the intakes themselves. The IntakeAir capacity of the intake just says how big this "tank" of IntakeAir is. And it's way too small, even in pre-1.0 airhogs, to run the engine for any measurable amount of time.

Instead, the main feature of intakes is that they create IntakeAir. As long as they create IntakeAir faster than the engine consumes it, the engine will continue to run. Any excess goes into the "tank" but again, it's not enough to make any real difference. If you see the IntakeAir resource bar going down, it's because the intake is making IntakeAir slower than it's being consumed, but only by a few decimal places. If you shut the intake, the bar would disappear almost instantly because the engine consumes it so quickly relative to the size of the "tank".

The rate at which intakes create IntakeAir depends on 3 main factors: intake area, airspeed, and air density. The bigger the intake's area and the faster the ship is moving, the faster you make IntakeAir. But the higher you go, the less air there is, so the slower you make IntakeAir. For a given amount of intake area, eventually a plane will reach a point where it's too high for the intakes to create IntakeAir faster than the engine eats it, despite traveling as fast as it can go. Then the engines will flame out.

Pre-1.0, you could solve this problem by just adding more intakes. Then you'd have much more intake area so could make sufficient IntakeAir even at very high alittudes to keep the engines running. But since 1.0, all jet engines (and the jet mode of RAPIERs) got a thrust curve that just falls off the table at about 23km. The engine will still run above that altitude but its thrust is so low that the plane will start decelerating. Therefore, it's now pointless to airhog anymore because jets are useless above 23km anyway. The good thing is, though, that because they keep running, we don't get the asymmetrical flameouts that used to plague SSTOs if they tried to fly too high.

Given that you can't use jets above about 23km anyway these days, you only need enough intake area to get that high. And as it happens, a single shock cone or ram intake per turbojet or RAPIER will do this. Having a tiny bit of extra intake area, however, will help ensure you don't have asymmetrical flameouts, so adding 1 precooler per engine can be beneficial, but isn't mandatory.

With the intake requirements defined, then it's just a matter of picking the best ones. There's really not much difference between rams and shock cones. The shock cone has slightly less area but has less drag so the plane will go slightly faster, which means you need slightly less dV for the rocket regime. But OTOH, because it has less area, you're more likely to need a precooler with the shock cone than the ram, which adds mass and some drag.

For SSTOs, I don't recommend using any auxiliary intakes except the precooler. The radial ones have way too much drag to be efficient and the other inline ones not only have more drag but also bulged/lumpy sides so are nearly impossible to attach wings to. And note that the "precooler" doesn't cool at all. It's just a small fuselage fuel tank with a built-in intake.

[Wolf Baginski]

I wouldn't recommend any part-mods for making SSTOs unless you just like the look of the stuff they give you.

Essential mods for designing anything are MJ or KER for all the stats that KSP doesn't show you.

I would seriously consider the B9 Procedural Wings, since they can much reduce the number of components, and a wing can include fuel tanks.

[Val]

... And note that the "precooler" doesn't cool at all. It's just a small fuselage fuel tank with a built-in intake.

You post is very good information and advice, except that last part about precoolers. They work roughly the same as Radiators, drawing heat from the surrounding parts and radiating the heat away.

[Wolf Baginski]

Also, common wisdom holds that once the jets are completely offline you should toggle all your air intakes closed to shave off a little more drag, but last I heard the jury is still out on how effective this is in the new version.

The R.A.P.I.E.R. can be set to auto-toggle between modes though the timing may not be ideal. I set up an Action Group to toggle the engines and the intakes together.

I have found single-R.A.P.I.E.R. designs to be a bit difficult to get up to the high-thrust speed region, but they're possible with small wings (lower drag) and small spaceplanes. This is where a parts-mod can pay off. There is at least one ultra-short cargo bay for Mk2 spaceplanes.

This is one of my successful single-R.A.P.I.E.R designs using stock parts. The wing is a bit bigger than it needs to be.

You could use a 1.25m Service Bay forward of the cockpit to carry Science, and the cargo bay maybe ought to be moved forwards. It works, but it's only a start.

It's a bit marginal, you could replace the cargo bay with a crew compartment, but where do you put the docking port?

[Val]

...

I have found single-R.A.P.I.E.R. designs to be a bit difficult to get up to the high-thrust speed region, but they're possible with small wings (lower drag) and small spaceplanes.

...

The reason you're having trouble getting up to speed is mostly because your design has a lot of drag from the fuselage. (Referring to the craft in your picture)

Reduce the wing area to 1 Lift Rating per 10 t and rotate the wings to have Angle of Incidence. Then you'll see your craft shooting through Mach 1 with no trouble.

[Wolf Baginski]

You post is very good information and advice, except that last part about precoolers. They work roughly the same as Radiators, drawing heat from the surrounding parts and radiating the heat away.

I find myself baffled by the use of pre-coolers. Maybe their characteristics, as an extra intake, are a slightly crude way of modelling what they do, though that would depend on the pressure and speed curves.

A wingtip mounted stack of intake, pre-cooler, and R.A.P.I.E.R seems worth trying, rather than some other 1.25m part.

[Val]

I find myself baffled by the use of pre-coolers. Maybe their characteristics, as an extra intake, are a slightly crude way of modelling what they do, though that would depend on the pressure and speed curves.

A wingtip mounted stack of intake, pre-cooler, and R.A.P.I.E.R seems worth trying, rather than some other 1.25m part.

Well. I didn't say they were worth using. Just that they do more than just being intakes and fuel storage. I personally don't use them.

[Geschosskopf]

Well. I didn't say they were worth using. Just that they do more than just being intakes and fuel storage. I personally don't use them.

I find no evidence that "precoolers" have any cooling effect whatsoever besides just being another part for heat to flow into normallly, like any other non-radiator part.

The actual radiators (fixed and folding) have an extra variable in the the main body of their declarations called "radiatorHeadroom". No other parts have this line AFAIK. The folding radiators in addition have ModuleActiveRadiator. No other parts have that module, not even fixed radiators.

The precooler is the "engineBodyRadial.cfg" file found in the Squad\Parts\Aero\engineNacelle folder. It lacks both radiatorHeadroom and ModuleActiveRadiator:

PART
{
	name = radialEngineBody
	module = Part
	author = C. Jenkins, Porkjet
	rescaleFactor = 1
	node_stack_top = 0.0, 0.9375, 0.0, 0.0, 1.0, 0.0
	node_stack_bottom = 0.0, -0.9375, 0.0, 0.0, -1.0, 0.0
	node_attach = 0.0, 0.0, 0.625, 0.0, 0.0, -1.0, 1
	TechRequired = hypersonicFlight
	entryCost = 6200
	cost = 1650
	category = Aero
	subcategory = 0
	title = Engine Pre-cooler
	manufacturer = C7 Aerospace Division
	description = Improves jet performance by pre-compressing and rapidly cooling the intake air.
	attachRules = 1,1,1,1,0
	mass = 0.15
	dragModelType = default
	thermalMassModifier = 1
	emissiveConstant = 0.95
	maximum_drag = 0.2
	minimum_drag = 0.3
	angularDrag = 1
	crashTolerance = 20
	maxTemp = 2000 // = 2900
	fuelCrossFeed = True
	bulkheadProfiles = size1, srf
	MODEL
	{
		model = Squad/Parts/Aero/engineNacelle/Nacelle2
	}
	MODULE
	{
		name = ModuleResourceIntake
		resourceName = IntakeAir
		checkForOxygen = true
		area = 0.005
		intakeSpeed = 10
		intakeTransformName = Intake
	}
	RESOURCE
	{
		name = IntakeAir
		amount = 0.5
		maxAmount = 0.5
	}
	RESOURCE
	{
		name = LiquidFuel
		amount = 40
		maxAmount = 40
	}
	MODULE
	{
		name = ModuleAnimateHeat
		ThermalAnim = Nacelle2Heat
	}
}

The only semi-unusual heat-related thing on the precooler is ModuleAnimateHeat, which is just for graphics, not function. It causes the part to glow red when it gets hot and is found in the cfg files for engines, nosecones, and a few other parts typically bearing the brunt of heat. IOW, it doesn't actually move, increase, or decrease heat itself, it just gives a graphical representation of the heat that's in the part, however that heat got there.

In real life, of course, precoolers don't cool off the whole ship, either. Instead, they're placed between the intake and the engine to cool off the incoming air which has just been significantly heated by being seriously compressed while coming in the intake. This is so the air can expand as much as possible when heated again by combustion in the engine, which is what creates the thrust. Developing an effective precooler has been (or still is) about the biggest challenge in making SSTO spaceplanes and is really the main claim to fame of the Skylon.

However, KSP's jet engine system doesn't care about the temperature of intakeAir, merely whether there's a sufficient amount of it available. Therefore, KSP SSTOs have no need of actual precoolers as in real life. So the question is, did Squad call this part a "precooler" just for aesthetic reasons, or is there some future plan to model intakeAir temperature and needing precoolers? Only time will tell. But in the meantime, KSP precoolers have nothing whatsoever to do with how the game handles heat.

Edited August 29, 2015 by Geschosskopf

[Val]

I find no evidence that "precoolers" have any cooling effect whatsoever besides just being another part for heat to flow into normallly, like any other non-radiator part.

The actual radiators (fixed and folding) have an extra variable in the the main body of their declarations called "radiatorHeadroom". No other parts have this line AFAIK. The folding radiators in addition have ModuleActiveRadiator. No other parts have that module, not even fixed radiators.

...

I could have sworn... I guess, I was wrong. Excellent detective work. Thanks.

...

Developing an effective precooler has been (or still is) about the biggest challenge in making SSTO spaceplanes and is really the main claim to fame of the Skylon.

I'm pretty sure they finished the precooler and have started construction/engineering on an engine prototype or proof of concept.

However, KSP's jet engine system doesn't care about the temperature of intakeAir, merely whether there's a sufficient amount of it available. Therefore, KSP SSTOs have no need of actual precoolers as in real life. So the question is, did Squad call this part a "precooler" just for aesthetic reasons, or is there some future plan to model intakeAir temperature and needing precoolers? Only time will tell. But in the meantime, KSP precoolers have nothing whatsoever to do with how the game handles heat.

Yeah, I'm disappointed that is has no cooling or radiating function. Imo, the RAPIER is a bit too powerful and needs something to balance it. Requiring extra cooling, would have been one way.

This (useless) craft actually works better with a pure air-breathing Rapier, than it does with a Turbo-Ramjet or a Rapier w/Oxidizer.

Javascript is disabled. View full album

Craft file

[GoSlash27]

The reason you're having trouble getting up to speed is mostly because your design has a lot of drag from the fuselage. (Referring to the craft in your picture)

Reduce the wing area to 1 Lift Rating per 10 t and rotate the wings to have Angle of Incidence. Then you'll see your craft shooting through Mach 1 with no trouble.

This is the conventional wisdom.

*however*...

A single RAPIER can accomplish more than most would assume. The key is to use *more* wing, not less.

The Mk2 fuselage makes more drag at 5° incidence than the parasitic drag of the wings required to get the incidence down to 3° at the same airspeed and altitude, so you make *less* net drag when you add more wings.

Therefore the correct wing loading (at least by my testing so far) is closer to 1:1.

Of course, this assumes that you're actually flying to orbit rather than following a gravity turn.

Best,

-Slashy

[Edax]

This (useless) craft actually works better with a pure air-breathing Rapier, than it does with a Turbo-Ramjet or a Rapier w/Oxidizer.

http://imgur.com/a/IeRNb

Craft file

And here I thought CR-7RAPIER stood for CRAPIER engine. That's disappointing to hear that my pure Lf-only SSTO should have been using Rapiers instead of whiplashes...[h=1][/h]

[GoSlash27]

Hot off the presses!

This is carrying way more cargo to LKO than a single RAPIER would normally do. wing Cl/ mass is a little under 1/2 on this one.

Best,

-Slashy

[Val]

Hot off the presses!

http://i52.photobucket.com/albums/g13/GoSlash27/Camacho2_zps1br9sray.jpg

This is carrying way more cargo to LKO than a single RAPIER would normally do. wing Cl/ mass is a little under 1/2 on this one.

Best,

-Slashy

It is better to have less wing and mount it with Angle of Incidence.

It's not just drag reduction as a benefit of angled wings (though that is certainly true), it also means your engines are thrusting closer to the prograde direction, which means lower cosine losses.

Single Rapier.

Take-off weight: 31 t

Dry mass: 9.46 t

Lift Rating : 5.52 (all mounted at 5 degree Incidence)

Mass of craft in orbit: 18.48 t (of this ~9 t is fuel = 2 FL-T800)

Cl/m: ~1/5.6

Javascript is disabled. View full album

Craft file

Edited August 30, 2015 by Val
Decimal error

[Starhawk]

It is better to have less wing and mount it with Angle of Incidence.

I thought from the picture that it was fairly clear that Slashy had angled the wings.

Happy landings!

[Val]

I thought from the picture that it was fairly clear that Slashy had angled the wings.

Happy landings!

I can't see it from the pictures, and that is not what I understood from his posts. But if that is the case, then I apologize.