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  • Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.

    Post 16 Update

    Post 17 Warning

Piglets XB-35: It isnt a video, yet...

ok, someone is lieing.
I'm pretty certain i have the power of the 4360 mapped at least semi correctly. and heres my finding so far..
Setting the MP to 30 inches ( 50% throttle ) and the RPM to 2000 ( 50% pitch ) the ONLY way to get this plane to fly at the specified cruising speed, is to give it as much drag as an office building.. It seems unlikely to me that that was the reality.. It IS however one way to squeeze those last few thousand miles out of the range and make it look all impressive..
Since its a flying wing and therefore has a much thicker cross section, i expect it to have a higher drag setting as everything is inside the wing, but the drag of a solid cube?? i dont think so..
I seriously need a protractor, a divider set, and a brain.. bear with me. I'm reverse engineering the design.. I want it right..

Addendum:

Found the issue.. That 183 mph cruising speed is based on the original three blade props that were fitted to the plane. I changed out the props for the three blade version and dropped the drag to something resembling a B-24, ad at 2450 rpm and 30 inches MP, the plane dropped to a respectable 187 mph..
But the three blad props proved to be too problematical. they were inefficient and caused a major amount of vibration, so the plane was fitted with a set of four blad props, which caused a little less vibration and for this application were far more efficient ( usually four blade props on modern aircraft are less efficient than three blade props )..

When the plane is ready for release, i'll try to have a set of more accurate speeds and settings for you..
 
bear with me. I'm putting numbers here where they wont get lost and i wont forget them..

Cruising speed @ 3000 feet ( 30 MP x 2450 RPM ) = 225 mph
Max speed at 3000 feet ( 54 MP x 2700 rpm ) = 320 mph.
Max speed at 20000 feet 9 54 MP x 2700 RPM ) = 390 mph
 
warchild said:
the ONLY way to get this plane to fly at the specified cruising speed, is to give it as much drag as an office building.. It seems unlikely to me that that was the reality..
Click to expand...

Pam, it's good to remember that drag in FSX is a bit goofy. The differential equations of motion in a sim are solved by the drag force, not the drag coefficient. Drag force is proportional to the drag area, which FSX calculates automatically (and un-adjustably). Since you're making a flying wing, I wouldn't be too shocked if this automatic calculation missed the mark. So it's probably expected that the Cd which gave the most realistic results seemed a little off.
 
JohnC said:
Pam, it's good to remember that drag in FSX is a bit goofy. The differential equations of motion in a sim are solved by the drag force, not the drag coefficient. Drag force is proportional to the drag area, which FSX calculates automatically (and un-adjustably). Since you're making a flying wing, I wouldn't be too shocked if this automatic calculation missed the mark. So it's probably expected that the Cd which gave the most realistic results seemed a little off.
Click to expand...

thanks john.. there's been a bunch of questions that didnt ad up in my head all day long..
a small story.. Three weeks after I started basic training at Ft Lost in the woods, a seargent busted into our classroom and announced that we had just gone to war with china. We of course didnt know any better as during basic training, we were pretty much cut off from the outside world.

Since that day, i have never ever believed military statements. too many times, i've seen the "they wont know so who cares " attitude, and I suspected their numbers as being just whatever they had to throw up at the time. Information on this plane is severely lacking any way and since they had to say something, they used what they had, which was for the wrong prop..

The numbers i just posted above are from tests that i'm currently running. the cruise is a bit higher than the original because of the props, but the low level maximum is definately lower, and comes up with altitude.. range at full speed right now is around 5000 miles. quite a bit shy of the max range of 8000 miles or 11000 miles i've seen quoted as well..

In airEd, my drag is set to 45 at the moment. For 183 mph with a four blade prop, i had to set it to over 100. considering all my other numbers are minimal, thats a major amount.. like trying to fly a skyscraper.. hell, skyscrapers have better aerodynamics than that was providing :;chuckles::. I "think" i've got it fairly close now, though only time will tell as we go on.. :)
Pam


PS. really what i'm doing is avoiding the stall characteristics.. They are singularly the nastiest part of this aircraft, and duplicating them is going to be very hard for me ( i'm smart, but, i dont know if i'm that smart ).
 
Floyd Odlum at Consolidated had a hot line right into LeMays humidor:icon_lol:! What about a second driver set written around 40,000hp for comparison. Not canon, as the TurboDyne looked more like some of the Avro Vulcan back of the envelope scketches Chadwick did.
Theres nothing like making lots of racket and going nowhere. Driving -215's across the pond, the fuel gauge would go down, lots of oil went over the side, and you went exactly nowhere for hours at a time. I swore once I saw a storm petrel go past us doing the sidestroke with a 25kt advantage on us!
 
The turbodyne is a possibility for a future project. Projected speeds however arent what you might think they would be as the props have to be geared down to keep the tips from exceeding the speed of sound, so, in the end, you would see maybe another 50 to 75 mph gain from it, but nothing more, and probably less.. Adding jets was the only way to get the wing to true performance levels you see now in the b-2, but without a system for the oversight of controlling the plane it was hopeless.. the big cowlings did help with stability, built, with the jet engines those cowlings went away and that stability was lost.
 
heh. this plane is interesting..
I just took it up to fourty thousand and the climb profile is unlike anything ive seen before.. its all dependent on air density.
Takine off from KSJC i set the climb to 15 degrees which gave me an indicated speed of 175 mph. I hald that angle and indicated speed all the way up, however, below 15000 feet my best rate of climb was about 2500 fpm. As i passed 15000, that began to increase until at 30000 feet i was climbing at over 3500 fpm. the rate of climb also began to drop off above 33000 feet even though the attitude remained the same. Maybe not so oddly was the fact that for the loss in vertical speed, the plane increased ground speed. I'm currently sitting at 41000 feet, at 448 mph TAS.
So uhhh.. who wants to race?? ::chuckles::

Pam

PS. Lazarus?? Whats a 215??

View attachment 50053
 
Sundog said:
I'm assuming he is referring to the CL-215 firebomber.
Click to expand...
Yup, the Duck( Yellow, floats most of the time) the slowest way to go anywhere. In Portugal, the Skyship guys challenged us to a drag (theres a pun there) race. We had to decline. Loosing to a blimp would be in the same embarasment category as the fighter pilot who got shot down by a helicopter. You would never be able to show your face in public again!
 
::roflmao:: I can imagine how embarrassing that is..

Might have a small ray of hope for you Lazarus.. I'm not doing the turbodyne yet, no, but..

As i cant wait for the hard copy manual to arrive in the mail on monday ( yip, i'm really that impatient ) I did some digging around and found the POH online.
( http://www.scribd.com/doc/50206334/...dook-for-the-XB-35-Heavy-Bombardment-Airplane )

originally i just wanted to learn where the fuel tanks were located. its not quite as cut and dry as it qwould seem, but on this plane, nothing is. Its part of the fun..

Now, The first thing that caught my eye was a recommendation warning to not fly this plane over 15000 feet. Kinda odd as its service cieling is 37900, but it gets weirder and better ( weird is too harsh really, the mixture controls are weird, this is just interesting )

The maximum permissible indicated airspeed is 360 mph. now, wait, cuz here comes the weird part, the maximum permissible speed in a dive is 325 mph. Putting these three pieces of data together tells me that this plane would fly 390 mph at 15000 feet. Thats because they make a point of saying the word "permissible" which tells me it can go faster, and making the other point to not go above 15000 feet ( contrary to urban myth, the flying wing could not carry an atomic weapon so higher was not needed although it was capable of it ). So whats the good news you might ask?? Well, the good news is you wont be stuck flying at 265 mph at low levels as its maximum speed.

I also spent some time watching the YB-49 from war of the worlds tonight. There isnt much there, but enough to figure out that its roll rate was about 27 - 30 degrees per second. Thats eighty feet of wing per side, moving that 30 degrees. the plane was no slouch.

one thing that bothers me is that no real life tests were made of extreme maneuvers. Therfore, we dont know anything about how this plane really flew beyond the normal flight demands of a typical bomber. NACA ran wind tunnel tests and they help, but wind tunnel is only an indicator and not ever used as empirical data.
I'm going to set everything up to reflect the documentation. Then I'll let you people decide whether i did an ok job or not.. :)
Pam

PS. One last link I found that you folks may find interesting.. Its Jack Northrops address on the flying wing, to the Orville Wright Society..

http://www.nurflugel.com/Nurflugel/Northrop/Northrop_address/body_northrop_address.html
 
warchild said:
one thing that bothers me is that no real life tests were made of extreme maneuvers. Therfore, we dont know anything about how this plane really flew beyond the normal flight demands of a typical bomber.
Click to expand...

It probably didn't have enough power for any extreme maneuvers. The YB-49 did and we know how that ended. Funny thing about flying wings in extreme alpha (For a wing) accelerated loaded turns, the center section continues to go up, while the outer wing panels twist down, ripping the airframe apart. There's sort of a point of no return in that regard, and modern software keeps the B-2 from exceeding it.
 
Hey, your welcome Roger :).. heheh. You know me, I like to yak with my fingers :), and this thing certainly has an interesting story behind it..
It just started coming together in my head this morning as i was waking up.. You see, Jack wasnt designing a bomber. He'd made the P-61, and could have cared less about bombers. He was designing a 300 passenger airliner, but he needed funding for it and the army was the only way to go for big over-sized planes. Conceived of when jets were known only to a few people i honestly dont think he anticipated the impact they would have. Topping that, due to production delays and cost over runs, he ended up competing against the largest meanest ( ugliest ) prop driven bomber ever made: The B-36, and later, directly with the B-47 Jet powered bomber. Everything was moving into the Atom age, and Jacks comparatively little flying wing with its small payload, never stood a chance, and his dream of a huge passenger liner capable of carrying 300 people from New York to Beijing in a single hop evaporated before his eyes as with the coming of the jets, his designs had to be modified beyond flyability. The YB-49 was fast, but, without those shaft housings on the back the plane was originally designed with, it was a piece of flying garbage.

In Germany, another visionary was doing the same thing in a different way. Werner Von Braun dreamed of a rocket that could reach out into space and beyond, but seriously needed funding for his research, so he disguised his work in the form of V-2s. In the end Von Braun's dream went to the moon; Jacks dream of a huge passenger liner smoldered for sixty years till one day he was wheeled into a hangar, and shown the realization of his dream, as the worlds most expensive bomber ever made. Its merely speculation on my part, and probably some romancing, but i think seeing the B2 instead of his passenger plane, actually helped to kill him..

So yeah, Just like I'm building the P-61 with Robert for all the Vets ( my brothers and sisters in arms ), I'm building this flying wing with Piglet, for Jack.

Pam
 
Sundog said:
It probably didn't have enough power for any extreme maneuvers. The YB-49 did and we know how that ended. Funny thing about flying wings in extreme alpha (For a wing) accelerated loaded turns, the center section continues to go up, while the outer wing panels twist down, ripping the airframe apart. There's sort of a point of no return in that regard, and modern software keeps the B-2 from exceeding it.
Click to expand...

Noo, it had plenty of power. You see, a flying wing only needs 40 - 60% of the power of a conventinal plane to achieve the same speeds and even greater range. Parasitic drag on a flying wing is only 80% that of a conventional plane, induced drag only 20% and Zero lift drag is negligible. This thing only needed 20000 horsepower to achieve the same performance of a conventional plane with 50000 horses.. Power wasnt the issue. The issue was, no one knew how to handle this technology. NACA moved the CG almost ten times trying to figure this design out. Now how do you move the CG on a plane thats standing still?? You cant. NACA was shooting in the dark and this technology was scaring them. Topping that, the Army/Air force wanted its new bomber and was in a rush to get it, so tests were never made beyond anything that would normally be encountered by a bomber. It was a matter of cost versus time..
the plane got a bad rap on its speed, not only because of jets, but, the B-36 could not only carry an atomic bomb ( which the Fling wing couldnt: remember, it was actually being designed to carry people ), it was faster. Well hell, The B-36 was a pencil with wings, six engines and an inverted fruit basket for a canopy. Yup, it was faster..

In its original design ( with props ) the YB-35 was a good plane. It just came too late, and was too advanced for anyone to grasp except Jack.

Addendum: The YB-49 was a Frankenstein. Once the props came off the YB-35 and jets stuffed inside the wing, the original design qualities that actually flew, was destroyed. But, it was the dawn of the Jet age. The air force still wanted a newer high speed jet powered bomber, and Jack still wanted his 300 passenger flying wing.. A match made in hell.

PPS:: yeahh, that twisting action is exactly what killed Glenn Edwards in YB-49-2. But thats a pure flying wing. No lumps bumps or anything sticking up into the wind. The XB-35 wasnt a pure flying wing though, and many of the forces encountered with protrusionless designs like the YB-49 and B-2 were avoided because in a sense, the XB-35 had a fuselage, and a vertical stabilizer ( four of them ). the center section however, did have a tendency to rise .. ( still does in the model ). However, Jack foresaw that twist and countered it in his design. The wing twist on the XB-35 is -10 degrees from root to tip. the more i study this plane and learn about jack, the more I stand in awe at his incredible genius..
 
Meh!.. I having problems with stalls and spins. Regardless of how nicely this plane could fly flat and level, it had some nasty stall/spin characteristics, and as every developer knows, stalls and spins in fsx are difficult at best. Cross your fingers ok?? I'm gonna do my best..
Pam
 
Oh yeah :)..
Dimensions, weights and most curves have been laid in now, and i moved from the alpha series of flight models to the beta series earlier this week.
The plane flies easily. Perhaps too easily. Rotation is at 117 mph and takeoffs are deceptively flat with a tendency to go nose high after takeoff. Unlike most aircraft that I've worked on, The aircraft is not surgically maneuverable. Its very difficult putting it into a single cubic inch of space that you wanted to put it into.
Banking is unique. the plane half rolls, half pendulum's its way into and out of a bank. it's a very odd sensation till you become accustomed too it.
Perhaps its FSX, but for a plane that weighs 183000 pounds, it sits real well on its wing tip in a turn with some nose down movement, but none of the slicing i would expect from such a loss of lift. I'm looking into that currently.
A couple new challenges have presented themselves and I've been enjoying the research needed to answer those challenges.
1. No testing of this aircrafts maneuverability was carried out beyond those maneuvers required of a bomber on a normal mission. That means that outside of the data gleaned in wind tunnel testing, we have nothing to go by to determine behavior in stalls, spins or emergency maneuvering.
2. Although an operational ceiling of 37,000 is given, nothing is mentioned in anything so far about an operational altitude beyond a recommendation in the POH to not take the plane above 15000 feet.We know that the B-36 ( the wings main competition ) had an operational altitude of 27000 feet and that it was capable of flying higher ( 43000 feet )than the B-35. At this moment, the wing will develop 20000 pounds of thrust, producing 387 mph at 15000 feet. I need to move that up to at least 19000 as i found evidence of some testing being done at that altitude.

Paul has the flight and visual models on the B-35 now, but is focusing on completing the P-61 since its flight model is 99% complete. We think.. While he's running his battery of tests, I'm examining what we've got on the B-35 at present and looking to match it against available data. for much part that means i'm having to wait till the hard copy of the POH arrives in the next couple days so that I can have it open in my lap as i walk through test after test and make adjustments. Personally i think we're doing ok so far. Perhaps not great, but solidly OK.. But then, its only been a week and a half.
Typical to Northrop, the VC of this beast is complex enough to give a genius a complex and I feel for Piglet as he tackles that. It'll be a while but I know your gonna like this plane.

View attachment 50316View attachment 50317View attachment 50318View attachment 50319
 
Wow, Pam, nice pictures.
What a wealth of information and dedication is shown in this thread!
Thanks for your work! I really look forward to this.

Cheers,
Mark
 
Thanks Mark. You know i'll do my best.. i've also got Delta558 beside me. he's been my partner in JFTC for years now, and he keeps me honest and on target.. truth told, i couldnt do it without him. I miss things these days, or get caught up in what ive done so much i cant see where to go next. Just today he was telling me that the XB-35 flies exactly the way he wished any plane could fly, and its wrong.. i like that, and need that too.. We know that Piglet is doing a class A model for you. I wouldnt think of doing anything less than my best for it.. :)
Pam
 
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