You should be able to make a gauge that directly controls the pitch of the prop, rather than letting FSX operate it as a constant speed prop. From when I was doing the Wyvern I have a feeling you can do it in XML rather than having to invoke SimConnect.the actual prop used was a full feathering variable pitch prop made by curtiss electric, but, fsx doesnt support variable pitch that i know of, so i made it a constant pitch prop.
yeahh, but will that allow us to vary the rpm of the engines?? thats what we need.. I mapped the props to a control ais, and can use that to vary the pitch of the prop, which varues the rpm of the engine, but its clunky at bast and i'm not too happy with that solution..Originally Posted by SkippyBing
I'm not totally sure what you're trying to achieve! As far as I know variable pitch props are almost always used with a constant speed unit, you essentially use the prop lever to set the desired rpm and the throttle governs the amount of power, better explanation here.yeahh, but will that allow us to vary the rpm of the engines?? thats what we need.. I mapped the props to a control ais, and can use that to vary the pitch of the prop, which varues the rpm of the engine, but its clunky at bast and i'm not too happy with that solution..
I'd be surprised if the P-61 did things differently as it would increase the pilot's workload considerably. If this is what the P-61 does then FSX models it anyway, you can write a gauge to schedule the prop pitch/RPM relationship differently if needed.
yeah.. the pilot had a good workload in this plane all right.. The army saw to it that it was about as complex as they could make it..
The P-61 has two sets of controls. A throttle which governs the RPM of the engine, and pitch levers to govern the pitch of the prop. I need the throttle to be a throttle and govern the engine in a way that it will reflect a deflection on the rpm gauge any time i change the throtle setting, and the pitch controls to govern the pitch of the props. In short, i need it to work right. as it was designed to do..
In flight, everything a pilot does is controlled by the rpm of the engines.. ( you watch for a 100 rpm drop when the magnetos go off, you dont fly the plane between 1700 and 2000 rpm because of buffeting, the list goes on) but if there is no deflection on the rpm gauge, theres no way to fly the plane properly. In short, i need a variable pitch prop instead of a constant speed prop.
if we can sever the ties with simconnect and let the xml control communications with the prop and the engine, that would be awesome. we could invent a variable pitch prop and have it work right the first time..
Hey All,
I have been following the thread since it got started. Your progress is in warp speed and can wait to fly the Black Widow. I also read that someone mentioned the aircrews were not thrilled about the visibility from the cockpit. Has anyone put any thought into the Northrop F-15A Reporter (it was a P-61 with a bubble canopy and was lightened up for speed, If not mistaken one was race at Reno and some were used for Fire-bombing). This was just a thought out-loud.
Cheers,
a26
Yup yup.. we've definately discussed both the F15 and the tanker rolls this plane has played.. the team made an agreement to finish one plane first, and then reconsider doing an F15. Now, the F-15 wouldnt be that difficult as it was originally an P-61B with the gunnery station and radar station removed.. But we want to get the one we got done first and then look at options for other models such as the F-15/reporter/tanker, The non turreted early A's and Late B's, etc.
Not sure about the racer. The P-61 project was closed down because of the twin mustangs that came out. The twin mustangs were over a hundred mph faster than the P-61 on an average day. The P-61/F-15 never was intended to be super fast. The F-15 specifically pointed out the glaring fact that no one knew exactly how to use the P-61.. Its best features were in the amount of ammo and stores it could carry and its maneuverability in relationship to its size and weight. Its extremely high wing loading ( 45 pounds per square foot i believe ) made it capable of doing stuff that was unheard of for a bomber sized ship, while its crew complement earned it the title of being the first team oriented aircraft ( even more so than bomber crews ), because if the team didnt act as a team, they were dead..
Still, 30000 pounds screaming out of the sky at 421 mph aint nothing to sneeze at.. but at best, in level flight, the girl can only get up to 351 mph and would be trounced by bears and mustangs in a heartbeat.
Be patient with us.. we got a ways to go on the B model, but theres a strong probability well aalso be doing the F-15 and reporter.
The C&D models utilized turbocharging and were considerably faster at altitude, well over 400 mph. Above 30,000 ft 2800 HP was available from each engine using Water Meth.
FSX (and FS9) both support animations of prop pitch change. Interesting how constant speed props work. A RPM and Manifold pressure are selected to achive a particular power setting for TO, climb or cruise. At high RPM's we will achieve the greatest thrust for takeoff and possibly climb, however lower RPM's loose less power through internal friction and propellers may have a greater efficency, so lower RPM values are selected for an efficent cruise setting.
When a RPM is selected the prop varies it's pitch to load the engine to maintain that RPM at a given throttle setting and airspeed. Throttle only controls RPM at low RPM's below the constant speed zone. What happens if the throttle is advanced at say a 2500 RPM setting, the prop will take bigger bite, loading up the prop and engine and applying the greater power to the airstream. Reduce the throttle and the prop will flatten out, taking a smaller bite and reducing the thrust.
Why not run low RPM's and High MP's? Not a great idea in real engines as it is possible to blow a jug right off the engine! Creates very high internal pressure! High RPM's, well, they create very high internal stresses due to the size of the rotating parts. The normal way of operating, increase the RPM and then the MP, or conversely, reduce the MP and then the RPM.
Cheers: T
copy that T. Thanks.. thats why varuable pitch props had a second pitch control that varied the pitch of the prop blade and not the rpms, but we dont have that option ( believe i tried some real crazy stuff this morning trying to make that happen.. HOWEVER!!
I've spent a LOT of time today focusing on nothing but the prop, and I'm happy to report that per the POH rpm will now rise to over 3000 during a dive, while maintaining 2700 during level flight and climb.. still tweaking a bit, but making progress..
The 100 RPM drop when you turn off a mag is standard in pretty much every piston powered aircraft, even R-22s and the controls are standard for a constant speed prop, pitch/rpm lever and a throttle.The P-61 has two sets of controls. A throttle which governs the RPM of the engine, and pitch levers to govern the pitch of the prop. I need the throttle to be a throttle and govern the engine in a way that it will reflect a deflection on the rpm gauge any time i change the throtle setting, and the pitch controls to govern the pitch of the props. In short, i need it to work right. as it was designed to do..
In flight, everything a pilot does is controlled by the rpm of the engines.. ( you watch for a 100 rpm drop when the magnetos go off, you dont fly the plane between 1700 and 2000 rpm because of buffeting, the list goes on) but if there is no deflection on the rpm gauge, theres no way to fly the plane properly. In short, i need a variable pitch prop instead of a constant speed prop.
Looking through the pilot's notes here on page 5 (6 of the PDF) it states each engine drives a four blade, constant speed, full feathering Curtis Electric propeller, and it then mentions propeller governor controls throughout the various checks, so I don't think anything fancy needs to be done with the controls.
Thanks for the Update,
I knew I saw something about firebomber, but I couldn't remember if there was a racer or not. I guess seeing a large tail number painted on the F-15 made me think of a racer. The good news that everyone is pulling together and making this bird come to life. Has anyone contacted Mid Alantic Air Museum (MAAM) in PA about the P-61 they are restoring the flying status. Since they intend to fly her (will be the only Airworthy P-61 in the Wolrd) they might be a good source of technical information. They might ever give a heads up the paint job they are considering. Last time I checked they had a rolling airframe minus the wing.... Just a Thought
a26
FSX has two propeller types: Constant Speed and Fixed Pitch.
Constant Speed Propeller is a variable pitch propeller and can be programmed to have reverse. FSX manages the pitch automatically, although you can do it manually too.
thanks guys.. yeah.. just went back through the POH and all the rpms given in there except for maximum dive rpm was under 2150 and part of the preflight checklist.. my bad.. thanks again..
The reason the dive RPM is in the POH limitations is that the R2800 is more tolerant of high MP (without detonation) than of over RPM. The engine in a high speed, steep dive would generally be driven by the prop, eventually reaching the pitch stop, at which point governing would no longer be possible and the RPM would increase as the load increased. I have not so far seen FS model this part of the engine operating range. In other words the POH says, watch the RPM's as well as airspeed/Mach if ya want two operating engines at the end of the dive....
I think the as is prop tables are pretty good, within the limits of the sim. Generally similar to the ones that I have used for various Corsairs (icl the F4U1-A, F4U-4, F2G, F4U 5-N), A26, P47-J and proabably a few other R2800 powered planes I have done over the years.
Cheers: T
Yeah. I wasnt questioning it, i was saying i got it to work right.. just not my day for communicating clearly i guess..
changed beta max and min, changed prop moi. eliminated prop fixed pitch beta.
Aircraft now climbs at 2300 fpm at 220mph. RPM slowly increases to over 3000 in steep dive.
Hey All,
Link to the Mid-Alantic Air Museum's P-61B Black Widow link http://www.maam.org/p61.html .
Possibly one of the most complex and detailed restoration ever done to date. It may even be better than the P-38 Glacier Girl and we all know how nice that restoration is.
Happy Flying :salute:
a26
Thanks for that...I already have it, and it has been a big help! :salute:
Thanks A26.. glad you put it there.. the amount of difference theyve been able to make in that plane is beyond amazing.. what they started with is nothing like what it is now.
You don't know until you ask the question!
It looks like they still have a long way to go before she will fly again, but considering the economy they are doing an outstanding job. I just wonder what the paint scheme they are going to decide on for such a special bird.
Did I say you Guys are doing a great job (you are)!
a26
(USAF, 18+ years)
:::LOL:: Thank you
On the MAAM P-61.. this is what she looked like when they found her http://www.maam.org/p61/images/MAAM-002_low.jpg The pilot was sitting up against a nearby tree with a broken leg waiting for rescue.. Kinda sad..
They've come a long way since then..
To the Team,
I'm glad to see that they were able to bring her back to the US, too many Warbirds are been ship off to overseas locations. It is truly sad that many will
never make it back home.
My grandfather was a Seabee’s during WWII and was on the CVE-98 USS Kwajalein. He saw several shot up birds land on deck and then pushed
overboard.
My Dad was in USAF in the 60's Korea/Vietnam AC-47's, T-28's, B-26'S, AC-119's, and F-4's (without guns), he saw many shot up and then scrapped.
Being sheet metal technician in the USAF, I can really appreciate all of the hard work being done on the her.
What you guys are doing by creating a detailed model for us simmers to enjoy is absolutely awesome and greatly appreciated by all of us warbird NUTS.
Sometimes it just has to be said, THANKS!
a26
I remember Shadow very well. A lot of us ground pounders are still alive because of her and her crews. Tell your dad i said thank you.
I was at my normal post on the back side of the Nha Trang perimeter one night when all of a sudden shadow opens up with her four mini guns about 2 klicks out. Within seconds, there were all kinds of secondaries going off. If it hadnt been for shadow, all that ammo would have been headed in my general direction.
Stay alive, and come home safe. ok??
Pam:
Making a few very small adjustments, Rate of Climb is coming into line nicely. Shoot you something later as I have a lot to do today, including changing the oil in the Supercub....
Cheers: T
;;;lol;; You and your super cub. I love it.. would love to see a photo or video journal of one of your flights.. would be wonderful..
Looking forward to your update.. Kind of a busy day here as well.. Have a presentation tomorrow i'm preparing for.. Real exciting stuff.. uh huh .. ::lol:;..
Loving the way we're constantly improving our work. We're getting amazing results and its a lot of fun too..
Warchild,
My Dad work specifically on the miniguns during his time in the service (AC-47's, F-4's, AC-130's and some AC-119's). He said it was something special being on board during real mission seeing all his work put to good use especially at night. He will be glad to hear about your day, who knows he might have been up there slinging some lead for you.
a26
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