SOH P-61 project

[Barfly]

Thanks Warchild for that historical background. It would be facinating to read old operating manuals for the airplane - intercept radar ops in particular, which I imagine are declassified at this point and available somewhere, and to a lesser extent IFF and gun laying radar. Though I think the latter two were developed for the C model, that was state of the art stuff for the day, and more detail would provide real insight into how advanced / capable the platform was. Does anyone know where to look for that kind of information?

[warchild]

Welll, The AI radar on board was quite limited, and required a second radar unit crew on the ground to guide the plane to within six miles of the target. Even so, the on board radar was an advancement on the british radar and consisted if the R/O position in the tail and a secondary screen on the instrument panel. The R/O's radar consisted of two screens. One screen displayed the horizontal deflection of the target, and the other displayed the vertical deflection of the target. What was displayed on the pilots screen is unknown to us at this time.. Once within a six mile range of the target, the radat operator could easily guide the pilot to within several hundred feet of it, and thats been supported by pilots stories time and time again. I have yet to read anything that demonstrates the pilot actually using the radar screen as an aid in navigation, although one story in describing a mission wherein the R/O guided the plane to within 300 feet of the target supports the possibility in that just as the R/O was getting ready to give the ok to fire ( or whatever the term would be ) the pilot opened up with all four canons. It is possible that the pilot used the small radar screen himself at that point but nothing confirms it and we still have a mystery.. These radar screens were nothing like what we have come to recognize as radar. In fact, we're not certain at all what the display was about. Originally, Radar displays were more like oscilloscopes and displayed a line of sine waves. How they were used i'm not certain. They were far from the user freindly bip that we came to know and love though..
Robert and i have discussed this aspect in derail before and i'm sure we'll discuss it more as we move forward. The fact that the horizontal display in the R/O's area was horizontal leads me to think that it used a sine wave display, as the vertical scan display is narrow and vertical (which would lend more to a sine wave focusing on vertical peaks in the wave ). Truth told though, we just dont know. The problem is, the team has almost exhausted the available documentation on the P-61, and what we need is a manual for the SCR-720 Western Electric radar. And thats currently the research i'm focusing on..

In following up on this comment i was able to find this page ( http://www.ibiblio.org/hyperwar/USN/...ars/index.html ) which contained this information.
""Indication and Data Output
Operator Station (far right): 1 5-inch CRT with type-B scan and 1 5-inch CRT with type-C scan.
Pilot's CRT (near right): 1 -3-inch type B (20 and 100 mile search and 10, 20, and 100 mile beacon), or type C (2 and 10 mile search). Vertical scale on C-tube extends from -15&deg to +60&deg. C-tube shows only targets within limits of range dial setting. Pilot also has range meter.""

Not being trained in radar operation I continued digging deeper which led me to this page (http://en.wikipedia.org/wiki/Radar_display#C-Scope) which displayed this injformation in regards to the type C scan display.
"A C-scope displays a "bullseye" view of azimuth vs. elevation. The "blip" was displayed indicating the direction of the target off the centerline axis of the radar, or more commonly, the aircraft or gun it was attached to. They were also known as "moving spot indicators", the moving spot being the target blip. Range is typically displayed separately in these cases, often as a number at the side of the display."

So we may assume that contrary to my above statement that at least one screen in the R/O's section, presented a blip or bullseye.. The second screen being a B type display ""provides a 2-D "top down" representation of space, with the vertical axis typically representing range and the horizontal axis azimuth (angle)"". The pilots radar was also a type B display with a range meter attached and located just above the pilots radar screen..

[PRB]

Pam:

http://www.vmarsmanuals.co.uk/archive/367_SCR720_Operating_Instructions.pdf

It doesn't look like an airborne radar set in this document, but heck, just more data...

This document:

http://www.history.navy.mil/library/online/radar-8.htm

Suggests the pilot had a "c-cope" type dispay, but it's unclear if they're talking abouy the P-70 or the P-61.

[warchild]

Paul. I dont know where you found it, but thats exactly what we need.. Thank you..
According to that manual if i'm reading it correctly ( and it isnt much different that the oscilloscopes I worked with when i was in the army ) the pilots screen is definitely a B type scanning device as when you decrease the range on the main unit in the back of the plane, the display on the pilots screen will disappear as it goes "off screen " requiring re-adjustment of the V sync to bring it back into view due to the change in function. This is precisely what we needed..
heh, anyone want to take a guess at how we can program a B Scan display or two??
_____________________________
heh.. it seems it may be easier thanm i thought .. Quoting the wiki yet one more time...

"The B-scope's display represented a horizontal "slice" of the airspace on both sides of the aircraft out to the tracking angles of the radar. The spot was swept up the Y-axis in a fashion similar to the A-scope's X-axis, with distances "up" the display indicating greater range. This signal was mixed with a varying voltage being generated by a mechanical device that depended on the current horizontal angle of the antenna. The result was essentially an A-scope whose range line was rotated to point up, and then rotated back and forth about a zero point at the bottom of the display. The radio signal was sent into the intensity channel, producing a bright spot on the display indicating returns."

well, maybe easier..


_____________________

More corrections.
Your right Paul. I confused the data on the pilots screen with the other data. It is indeed a Type C display.. My apologies.. ( ummmmmmm, can i blame this on the plane and data i'm researching being complex and confusing enough to throw off my senile old perceptions?? )

[warchild]

Robert..
This is for a different unit than what we have, but it may help us to unravel what the pilot was seeing on the radar screen..

http://www.ibiblio.org/hyperwar/USN/...lotsManual.pdf

[Barfly]

That AN/APS 6 manual you posted is fantastic. I had no idea how precise and capable those early sets were - really good stuff. And real color photos of the actual scope returns! Maybe the SOH F7 team can use it at some point - I believe the F7f-3N nightfighter used this set.

[N2056]

That's good to know...as I am the one that will be putting the Tigercat into FSX :salute:

[Cag40Navy]

Sweet stuff guys. And Pam, i made it to Panama in one piece.

[roger-wilco-66]

Awesome stuff around the radar.

How about a nice feature of the radar, a radar operator that tells the pilot the bearings to the bogey in, say 30sec intervals?

And semi-OT: If you succeed in programming this, do you think it would be possible to create an independent radar gauge for detecting ship traffic? Aircraft like the PBY, Dauntless, Helldiver, Hudson and many others had these sets on board, would be nice to have something like this around.


Cheers,
Mark

[warchild]

Ultimately, i'd love to see three people in the plane at once during multiplayer sessions, but i know thats impossible with fs host, so your idea may be an alternative. The difficult part is getting a radar that will display other players aircraft as well as Ai. there was a couple radars in fs9, but one was external to FS and the other was part of a fire truck. Both however worked in multiplayer..

[roger-wilco-66]

[...]The difficult part is getting a radar that will display other players aircraft as well as Ai.[...]

I'm not a good programmer, but I see that there are a lot of interesting commands for the Simconnect API, like

SimConnect_RequestDataOnSimObjectType

The SimConnect_RequestDataOnSimObjectType function is used to retrieve information about simulation objects of a given type that are within a specified radius of the user's aircraft.


Theoretically, as far as I can judge it, you even can have an AI flight (e.g. enemy ) that could be taken over by the simconnect client as soon as you come near it or have it on the radar. The sc client (of which the radar is an instance) can do all kind of things, from evasive action for the ex-AI aircraft or maybe even a scripted shoot down scenario, or release it back to the AI flightplan for a missed radar interception.

But as I said, I'm no programmer, just musing around.

Cheers,
Mark

[warchild]

that would be very cool indeed, especially as the R/O is the only person who can see behind the plane.. and if we can get two planes able to do the same thing, we can begin to open up whole new worlds to multiplayer events online. At the very least, it would allow someone to locate their friends via radar, and join them in mid flight, and at the very most, it would allow for the development of competition, perhaps even full re-enactments. A2A could probably do it with their eyes closed, but if they do it, truth told, our little P-61 would never be able to use it because we haven't got a dime for buying anything, let alone the costs of licensing a product. Worse yet, Unless one of my people has some very special abilities they havent told me about, we dont have a systems programmer on the team.. i would love to do this, but truthfully, right now its more of a prayer than an inevitability, and if some payware house gets there first, we can probably kiss it goodbye..

What would also really be cool would b to get a voice for ground ops to guide the planes in to the target area. Nothing would show up on the screens, it would all be voice guidance till you were within range,, then ground control would pass off to the R/O and you would be in business..

[N2056]

In the course of working on the final mapping of the wing I wanted to be able to get the ability to dirty up the inner surfaces of the scoops that are built into the wing. The outer scoop has been "weathered", the inner has not.

Attachment 22043

[warchild]

I like that outer scoop a LOT.. it looks right.. good job will be on ts in a bit.. need to test something first b..

[jankees]

Looking very good, that scoop!

[warchild]

Well, its been a few days since i've posted anything here.. Work on texture mapping and modeling continues smoothly. I however have run into a conundrum That i need your help with..

you see, in FSX if your flying at full speed ( or any speed really ) and pull back on the throttle, the plane slows down, the rpms drop and you can easily land. The P-61 however is proving different.

In a real aircraft, the rpm is controlled by prop pitch, and the P-61 is acting no different. The throttle controls the manifold pressure. So what happens is that when you pull back on the throttle, the manifold pressure drops, but the rpms stay the same. Therefore, the plane will slow down to the point that the torque of the engine ( rpms ) and the manifold pressure reach an equilibrium. In the P-61 that means about 210 mile per hour unless the prop pitch is adjusted. However, if the prop pitch isnt adjusted, the governor will do everything it can to maintain a specific rpm.

I know this doesnt sound like a problem. Its an ideal really, but how many of you can adjust prop pitch on the fly? How many of you have controllers with the prop pitch mapped to an axis?? Therein lay my problem, and i'm not sure what to do.

[modelr]

Saitek flight controls...
X52 = pitch control mapped to one of the wheels on throttle handle. Mixture mapped to other one.

Control yoke with extra throttle quadrant, allowing 2-4 engine control with throttle/mixture/pitch control.

I would suggest standard control mapping. You are doing fantastic so far, don't try to "dumb it down" for those without axis controls. They have keyboard controls if necessary.

[rohan]

modelr expressed my sentiments exactly - no "dumbing down", please ...

[PRB]

In FSX, if you're flying a plane with constant speed props, reducing manifold pressure doesn't automatically decrease RPM. The RPM is maintained constant by that “constant speed prop” mechanism, just as in a real plane. Of course, if you reduce MP enough that the constant speed system is unable to maintain the “selected” RPM, the RPM will decrease. But, either way, the plane's air speed will always slow down if you pull back on the throttle, be it a fixed pitch Cessna 150 prop, or a P-61. It's just that in the case of a constant speed prop, the system will try to maintain the selected RPM when MP is changed. So, when you reduce MP, the props, under less power delivered from the engine, will flatten out the pitch, causing less air resistance to the blades, just enough to maintain the selected RPM. This causes the thrust delivered by the prop to be reduced, because it's “biting” less air, and the drag induced by the prop, to be increased, both causing the airplane to slow down.

So, if you're saying that reducing MP in our SOH P-61 isn't resulting in a reduction in air speed, unless you also alter the prop RPM, then I would agree, we (Houston) have a problem. I think... But I'm not sure I'm following what you're saying here... It sounds like you're saying that the speed of the P-61 is affected more by prop RPM than by engine MP, which would be bad, I think...

The MAAM B-25 is probably the best modeled plane I've ever seen with respect to this RPM / manifold pressure relationship. It's still confusing as heck to me, so I may not know what I'm talking about.

In any case, I agree with the above sentiments – no “dumbing down” please...

[warchild]

You got it.. No dumbing down.. I promise..

[N2056]

This week I managed to get things working on the right wing, and have rough-draft mapping done on the crew pod.

Attachment 22496 Attachment 22495

[Cag40Navy]

Lookin Nice!

[rohan]

thanks, Pam

[warchild]

Because my writing skills are horrible, and because i've never done a manual before in my life, my dream of dreams is to get the plane to the point where i can just point people at the US Army training video and the pilots handbook for the real plane.. I think my team has the same dream. I cant speak for them though.. It'll take time, but we'll get it right..

By the way.. Wanted to thank all the guys that were flying online tonight.. I didnt want to intrude, but it was great seeing you all, and made my normally empty little world, not so empty for a while.. Sorry about crashing while i was trying to snap a picture....
Pam

[stansdds]

Do the cockpit modeling as close to the real P-61 and flight modeling/engine operation as well and the pilot's manual should be all one needs. I'm all for accuracy and flight model fidelity. The more realistic it is, the more I like it. This P-61 is looking really good.