DC Designs Northrop P-61C Black Widow RELEASED
- Thread starter DC1973
- Start date
Pam, Very sorry to hear you are having a bad day, at least my half a blue pill 3 times a day is helping contain my Parkinsons tremors!
Anyway did a back of the envelope MoI calc according to the FS9 SDK & got
Pitch = 77235
Roll = 59283
Yaw = 110376.
I deleted the cross coupling.
Then found that the contact points wheel radius is actually the dia ( by scaling the onscreen model), so have halved that & then col #10 for the nosewheel damping was 12.98, so now its .98.
This has stopped the jitters which can be seen from the onscreen g reading, not jittering. Unfortunately the props still will not stop!
Tried a few prop alterations too,
Prop rotation was 1,0, now 1,1
beta min now 10
min gov rpm now 800, otherwise rpm too great & hence HP throttle closed so taxy speed 30 kts! Need to put prop pitch to coarse though.
low speed theory now 80.
There doesn't seem to be the necessity to change pitch or throttle at 300, it will pass through it albeit slowly - I got to 388 mph.
After all this the props will not stop - now the only thing I can think is that the prop still notation in the model mdl is wrong, as cannot see anything else that would affect them.
AFSD shows a negative rpm & gives a HP reading!
Now these work for me, might not be correct though. I still need to get more rudder authority, but thats probably in the air file.
Keep your chin up Pam, we are rooting for you.
Keith
Anyway did a back of the envelope MoI calc according to the FS9 SDK & got
Pitch = 77235
Roll = 59283
Yaw = 110376.
I deleted the cross coupling.
Then found that the contact points wheel radius is actually the dia ( by scaling the onscreen model), so have halved that & then col #10 for the nosewheel damping was 12.98, so now its .98.
This has stopped the jitters which can be seen from the onscreen g reading, not jittering. Unfortunately the props still will not stop!
Tried a few prop alterations too,
Prop rotation was 1,0, now 1,1
beta min now 10
min gov rpm now 800, otherwise rpm too great & hence HP throttle closed so taxy speed 30 kts! Need to put prop pitch to coarse though.
low speed theory now 80.
There doesn't seem to be the necessity to change pitch or throttle at 300, it will pass through it albeit slowly - I got to 388 mph.
After all this the props will not stop - now the only thing I can think is that the prop still notation in the model mdl is wrong, as cannot see anything else that would affect them.
AFSD shows a negative rpm & gives a HP reading!
Now these work for me, might not be correct though. I still need to get more rudder authority, but thats probably in the air file.
Keep your chin up Pam, we are rooting for you.
Keith
warchild
Charter Member
Oh gods I hate the tremors.. I get them any time my blood oxygen drops or I get overstressed. The VA diagnosed me with "Parkinsonians like disease" a long time ago after my motorcycle accident where i came down on my head.. hehehe.. I'm brain damaged ::lol::... Glad you got it covered.. Damned shakes rive me nuts..
Anyway.. I would think that that .98 in colum 10 would cause your nosewheel to dive into the pavement when you hit the brakes.. Thats why it was so high. I just kept making it higher till the wheel stopped going sub terrestrial..
Your correct about the rudder. That is located in section 1104 in the air file I believe. and is under the yaw sub section.However, I believe you might be better served simply by lowering the weathervane entry. We designed the fde based around reports of reports of Johnny Meyers tyranical insistance of how the plane needed to be built, while he was chief test pilot for the project. It could be flown by an eighteen year old farm boy from Iowa whos never seen a plane before, and it'll bring him home safe.
That and the MOI's were finalized in 2012 so, things are much different now and perhaps its time for me to take my own advice and update all the old data..
Oh, days not bad. Just emotional and cant breathe but i'm winning that one too, for the moment
..
Josh Patterson
SOH-CM-2023
prop control
Just wondering the trick to the prop control on this and the Reporter. I have trouble finding the sweet spot. If I pull the prop control from where it is initially it will bring the RPMs down as expected but then they will rise again. If I push it they rise very slowly. I can get it off the ground, but it takes more work than I am used to. (Usually on these big radials I take off with about 50" MP and about 2500 RPM. Even when I initially adjust the Widow and Reporter to this they just don't accelerate and I have to walk the RPMs through 2500 till I get to the setting that works.) Looks great and fun to fly once off and trotting though!
Just wondering the trick to the prop control on this and the Reporter. I have trouble finding the sweet spot. If I pull the prop control from where it is initially it will bring the RPMs down as expected but then they will rise again. If I push it they rise very slowly. I can get it off the ground, but it takes more work than I am used to. (Usually on these big radials I take off with about 50" MP and about 2500 RPM. Even when I initially adjust the Widow and Reporter to this they just don't accelerate and I have to walk the RPMs through 2500 till I get to the setting that works.) Looks great and fun to fly once off and trotting though!
SH427
Members +
My experience dictates that the weight of the props won't allow you to go at or above 2500 until you're well down the runway on your takeoff roll. Once I get it stable (I fly VFR at about 3-4k') I usually pull back to 2000 or 2100 and 40" of MP, that'll get you up to 300 mph pdq
& Josh's comment - I got over that with my mods to the aircraft.cfg prop values mentioned above, basically with the unmodified values the prop is too coarse pitch & acting like a fixed pitch prop, making it start at 10° helped, but one needs also to reduce the min control rpm.
These are all things that I have never had a problem with before, so flummuxed as to why they are appearing now - could it be the use of Jerry Beckwiths program putting hidden things in the software?
Keith
Bit more info on prop rotation cold & dark - the problem lies in the airfile item 509, the graph has no negative x value; normally a neg y value is needed for the first point neg x. followed by the same values but positive values. I need to trim mine to get the prop to stop in time with the sound, otherwise the remaining values so far are OK. Sounds greek? Will try again tomorrow.
Also fiddling with the rudder in the 1101 air file, got a bit more control but not enough. Still need to go to coarse pitch on landing to reduce power. Thats the next hurdle.....
Good night
Keith
Also fiddling with the rudder in the 1101 air file, got a bit more control but not enough. Still need to go to coarse pitch on landing to reduce power. Thats the next hurdle.....
Good night
Keith
warchild
Charter Member
Hmmm. You pose an interesting question. Let me see if i can answer it.
You see, I never use prop control. The manuals dont talk of it either. Instead the manuals use MP and RPM. The problem is, something happened when i connected a supercharger up to the turbocharger and now, it seems rpms are dictated by the throttle. Thats not the case with the P-61B however, and that confuses me because they both use an almost identical FDE, but thats not the case at this time.
The P-61s use Hamilton Standard Electric propellers. These are self adjusting propellers. There is no sweet spot. Unlike some planes where you set the pitch and the rpms follow, on this plane, you set the rpms and the propeller pitch follows. however, as you climb, cruise dive bank and turn, the pitch of the propellers is constantly being adusted. You just dont normally see it as there isnt a gauge to show it.
My recommendation is to set an axis for rpropeller rpms and use that instead of prop pitch. Takeoff is max rpms ( 2700 ) though most likely youll be in the air before you hit 2300 rpms. The plane is incredibly powerful. It also weighs half again as much as a fully loaded B-25 bomber at 34000 pounds. At the beginning of your takeoff run, the blades follow the throttle until they are at maximum pitch. As the plane overcomes the weight ( MOI's ) the blades adjust and trim to a finer pitch. As you rotate and begin your climb, the blades once again go to full pitch and bite into the air to pull you off the ground. aand up, and your rpms stay low. What I do is after takeoff I level out and wait for the rpms to come to full ( 2700 ) then i throttle up and begin my climb.
The base rule of thumb is to set your MP to 54 I/Hg and rpms @2700 for takeoff. For cruise Set your rpms to 2400 - 2450 and your MP to 50 I/Hg. 45 I/HG is also acceptible. cruise is 315 mph, though it'll probably creep up to 350.
hope this helps a little bit..
Pam
Pam, I normally don't fly with anything checked that will cause me to have a bad flight (crash detection, engine exploding, airframe coming apart in mid-air, etc), lol. However after reading all the previous posts and all the adjustments people are making to the airfile and cfg file I decided to do my worst and check everything available.
Amazingly, your description above matches what I found without doing anything other than simply "Flying the airplane". . .what a concept, lol. I also level off after gaining some altitude, enough to clear tall grass, low trees and little birdies. . .and allow the airspeed to increase to a respectable level for a 1000'fpm climb rate. By the time I was at 4000' I was at 300kias. I flew like that (adjusting the RPM's to 2400 and MP to 45in) and flew from Nantucket to Logan. Then I decided to take the flight to Loring, Maine and so I began a climb to 24,500 (just below critical altitude). I maintained a climb rate of a rock steady 1000fpm at an airspeed of 300kts. It took an additional 120nm to make it to 24,500 and then leveled off and again adjusted the RPM's to 2200 and the MP to 42in which gave me a ground speed of 412kts. I failed to keep an eye on my distance to Loring and after fiddling in the forums a bit found myself just 54nm from my destination and still humming along at 24,500, lol. I set the descent to 3000fpm, pulled the rpm and Mp settings back to keep things respectable and when I was 10nm out I was just under 4000' (airport elev. is 750approx). . .set up for landing and touched down with nary a puff from the tires. . .a beautiful airplane. . .you should be proud of the work you did on the FDE. . .splendid.
warchild
Charter Member
warchild
Charter Member
Thanks Ed.. I'm very proud of her.. Theres a few gotcha's that popped up that have me scratching my head still, but i'll get those ironed out and update everyone. Nothing manjor.. Just you knoiw, accelerate down the runway and the plane suddenly decides it has to go exploring to the left and nothing you do can change itszs mind.. I'll figure it out though, i promise..
Love your flight description. I was flying out of dulles looking for trouble today. Found it too, about forty miles northeast. It had everything. super cell, wall cloud rain wrapped area where a funnel should have been, but no funnel, and the worst rear flank downdraft i've ever seen. stopped the plane dead, and smashed me too the ground.. It was amazing :
: I'm going to make a special version of the thunderstorm plane outfitted with weather radar, gps, and an efb where i can tie into the web and download the latest doppler returns from the NOAA. Then i'm going hunting and blending real world storm chasing, with in sim storm chasing.. .. I've loved this plane since the day Rick first gave it to Robert and I, in all of its incarnations.. I cant tell you how much it means to see so many enjoying it. And you. Your a vet, my brother in arms, AND a pilot who just happens to fly the occasional relief mission after a hurricane.. Your special Ed. And i want to thank you.. 
Excellent flyer all around but I have noticed that the props seem to turn the wrong way at start and running to I suppose. By wrong way I mean against the angle of the prop if that makes sense. They are turning to the port wing tip but the blades show they should be turning to starboard. Otherwise been having a lot of fun with your splendid fde, Pam!
warchild
Charter Member
I had initially reversed one prop to help troubleshoot the problem where the plane pulled to the left, but it took your comment to spur me into going through and finding the culprit.. For that, I thank you. However, my cat is not happy.. Your astute observation and the resulting inspiration lead me to change my position as i opened the files to edit, and that woke him up as he was sleeping on my lap.. Poor kitty :
: The solution is below.. Thank you for that.Pam
warchild
Charter Member
_Please read and do... Thank you..
All of us have been having problems with the plane pulling to the left on takeoff.. My bad.
Would you all please open your aircraft.cfg file in notepad or notepad++?
Scrolling down to the [Propeller] section locate the line that reads "rotation=" and change it to read "rotation= 1,1.
Next scroll down too [AntiDetonation System.0] and on the lines that read "reservoir_size = 48 ; gallons" AND " flow_rate = 1.3 ; gallons per minute" delete the ;'s and replace them with double back slashes (//).
Thats it. go fly
I do apologize for missing the typo's.
Another update will be coming in a few days..
Pam
All of us have been having problems with the plane pulling to the left on takeoff.. My bad.
Would you all please open your aircraft.cfg file in notepad or notepad++?
Scrolling down to the [Propeller] section locate the line that reads "rotation=" and change it to read "rotation= 1,1.
Next scroll down too [AntiDetonation System.0] and on the lines that read "reservoir_size = 48 ; gallons" AND " flow_rate = 1.3 ; gallons per minute" delete the ;'s and replace them with double back slashes (//).
Thats it. go fly
I do apologize for missing the typo's.
Another update will be coming in a few days..
Pam
Lol I know how that is as well! I say to the cat, I have get up, Cat says no you don't.I had initially reversed one prop to help troubleshoot the problem where the plane pulled to the left, but it took your comment to spur me into going through and finding the culprit.. For that, I thank you. However, my cat is not happy.. Your astute observation and the resulting inspiration lead me to change my position as i opened the files to edit, and that woke him up as he was sleeping on my lap.. Poor kitty :
Pam