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

[warchild]

but, we're making good strides. As Piglet focuses on that VC, I've turned my attention to the flight model for real.. I sent him FDE Alpha-0 today. Its the starting point, and we're off to a good start. Theres a long road ahead for both of us, but, already, I was able to take it to 40000 feet, aand 411 mph ( or 20 mph too fast ). On landing, she floated like a leaf. Not fun in any way shape or form, but too my delight, i learned that thats exactly how the real bird flies.. A good start?? I think so :)..
Stay tuned. I'll keep you all updated as time goes on. I guarantee youyr gonna want to flyn this thing when its done..

Pam

PS: New technique for landing: Extend the flaps to slow down to landing speed. At fifty feet off the deck retract the flaps and flare.. Very odd, but it works..


49929

[kilo delta]

Hmmm..I think I'll be doing most of my XB35 flying at Edwards in that case!:icon_lol:

[TARPSBird]

Hmmm..I think I'll be doing most of my XB35 flying at Edwards in that case!:icon_lol:
You should see me trying to land a B-52 at Clark AB. I take the scenic tour of central/northern Luzon just trying to get one good line-up on the runway. :icon_lol:

[warchild]

well, we have the float right, and last night i started dialing in the falling leaf yaw that wings exhibit in a bank. One of the things I'm going to be paying very close attention too in this is the stall, but a lot of research has to be done first. You see, in a conventional aircraft, you have a tail plane that is lower than the main wing during a stall, and it being the first to encounter airpressure as the plane drops, rotates upward and places the attitude of the plane in a position that is generally recoverable. You dont have that on a wing. when you stall nose up, the center of mass inside the wing drops to the back of the wing and you have a knife edge effect. The wing will simply slide backwards all the way to the ground.

The conflict i have however, is that these reports of this happening, center on the YB-49 ( a singularly nasty plane ). The greatest majority of complaints on the XB-35 center around the federally provided gearbox, its inability to carry fat man ( our atomic bomb at the time ) and the propellor shafts. So far, not a damned thing is mentioned about any negative flight characteristics, outside of the fact that it was slower than a jet. Ergo, it was obsolete before construction even started.

One piece of information that i did find was that accordingly, it could take up to four minutes of work after takeoff, to get the plane stable. But once it was stabilized, nothing is said about. Everything at this point, appears to be mechanical problems ( an area we cant do anything with in fsx ).
I ordered the xb-35 poh last night. It should be here in a few days. Hopefully, it will have details in it that will help me zero in the flight model all that much more.
Pam

PS. I'll say one thing. Once this plane is in the air, and with a rather unique viewpoint in the cockpit, its addicting as chocolate.. :).. Its hard to work on it. I'm having such a great time flying it, I hate putting it down to use the calculator..

[kilo delta]

I ordered the xb-35 poh last night. It should be here in a few days. Hopefully, it will have details in it that will help me zero in the flight model all that much more.
Pam


Did you get the one I sent,Pam?


Some info on the XB-35 Flight characteristics here (http://www.warbirdforum.com/northrp4.htm) and here (http://www.flightglobal.com/pdfarchive/view/1947/1947 - 0942.html)

[warchild]

yup yup.. but having a hard copy will allow me to make changes dynamically as I'm flying. with my memory fading its a nice thing to have.

[Bomber_12th]

I know I have seen the XB-35's max speed listed at 391 mph, but that really seems far out there (that would be reading true airspeed, not indicated - very important to know and understand). Though perhaps at 35,000 ft (at which that max airspeed could only be attained), the thin air at such a high altitude allowed the aircraft to reach such a velocity.

The XB-35's cruise speed was only 180 mph - much like a B-24 - vastly less than what was hoped for (quite a bit less than a B-29), and what was eventually reached when jets were added.

As one of the XB-35 and YB-49 test pilots, Charles Tucker, has written:

"The XB-35 was very sluggish in flight; it always felt as though it was just wallowing around in the sky. It had [a] myraid of problems, mostly centered on the engines and propellers. The airplane was underpowered to begin with, and the drive train and propeller arrangement added to the problem. The propellers were mounted at a large angle to the wing’s chord line, [like] the N-9M, and this considerably impaired efficiency. First, contra-rotating propellers were used, and the propeller gearbox was very weak. Problems with this gearbox quickly led to the redesign of the drive train to eliminate the contra-rotating feature and to use single-rotation propellers. This further reduced the efficiency of the propulsion system.<o:p></o:p>
<o:p></o:p><o:p></o:p>
The XB-35 was designed to use four of the then experimental Northrop Turbodyne gas-turbine engines, of approximately 10,000 hp each. This engine never attained flight status, so the decision was made to power the XB-35 with four Pratt & Whitnet R-4360 reciprocating engines of approximately 3,000 hp each. These engines simply were not powerful enough for an airplane of this size. The decision to rebuild the airplane as a jet solved the power problem."

As one can attest to in almost any other airplane, when you are flying it at an airspeed which is less than normal/designed cruise, especially much less, you will notice that the aircraft just doesn't want to fly well at all, or at least not as well as you are used to it handling, with everything being more 'mushy' in control, more so as the speed decreases. I'd suspect, that with the XB-35 being so underpowered, and not flying at the speeds originally thought for it with much greater power, it would just seem to 'wallow around', just as Charles Tucker put it. With the YB-49, the added power seemed to make the aircraft fly as well as the design was originally intended to be.

[Bomber_12th]

Here's more from the write-up by Charles Tucker, as included the article "Flying Wings", featured in the October 2003 issue of Flight Journal. I've included the bit about the N-9M, for anyone who might be interested in it.

The N-9M

The N-9M's wingspan of 60 feet was approximately one third that of the XB-35/YB-49's 172 feet. The N-9M aircraft were designed to test Northrop's ideas on all-wing aircraft as a proof of concept to build the XB-35. By the time I flew them, just about all of the engineering data had already been gleaned from the N-9M program, but it was nevertheless a very valuable learning tool for me. I eventually logged about 40 hours in the airplanes.

The N-9M's handled well but had a few little idiosyncrasies. One was that in any sort of disturbed air, the airplane displayed a low-amplitude, high-frequency pitch oscillation. This was because of low damping owing to its low tail volume. If flown at around 22 or 23 percent of the mean aerodynamic chord, the airplane wasn't unstable in any way; it just didn't damp well.

The airplane was virtually immune to the common problems encountered during crosswind landings. It was so unbelievable that a crosswind could have hardly any effect on an aircraft during landing that I used to look for runways with good, stiff crosswinds and land on them because it was so much fun.

The last three N-9M's were the first aircraft built with a full-power, irreversible, hydraulic-power control system. One characteristic of the first manual-control-system N-9M was that during high angle of attack, the large elevators tended to float upwards and move the stick back. If the pilot could not overpower the elevators and push the stick forward, it would be forced into his stomach and pin him to his seat. This was the direct cause of Max Constant's fatal crash in the first N-9M. Evidently, when up-elevator was applied to initiate a stall, the elevators floated to the full-up position, and when the stick came backward, Constant wasn't able to force it forward to break the resultant spin, and he couldn't free himself from the seat to bail out. This trait was shared by some of the prewar European flying wings, and it caused a few crashes on that continent, too.<o:p></o:p>
<o:p></o:p>
The XB-35<o:p></o:p>
<o:p></o:p>
Following my experiences with the N-9M, I was assigned to fly as copilot in the XB-35 and YB-49. The copilot was rather superfluous, as the [copilot's] cockpit was in the leading edge of the wing, and the only visibility was straight ahead. You could not take off or land from this position, as there were no throttles or brakes. I flew about 50 hours in the XB-35, and in that time, I actually flew the airplane for about five minutes. That isn’t much, but it was enough to know that I really didn’t like it.<o:p></o:p>
<o:p></o:p>
To this single-engine fighter pilot, the XB-35 and the following YB-49 were visually impressive. They were huge! Crew entrance was via stepladder through a two-foot by two-foot hatch in the belly. Once aboard, getting to the crew stations was quite a job; it required crawling over, under and around various parts of the aircraft’s structure. From the command pilot’s seat, the view was magnificent! The biggest problem was that if an emergency exit became necessary, you were in trouble because there weren’t any ejection seats. Getting out in an emergency would have been almost impossible. This was something you just tried not think about.<o:p></o:p>
<o:p></o:p>
The XB-35 was very sluggish in flight; it always felt as though it was just wallowing around in the sky. It had [a] myraid of problems, mostly centered on the engines and propellers. The airplane was underpowered to begin with, and the drive train and propeller arrangement added to the problem. The propellers were mounted at a large angle to the wing’s chord line, [like] the N-9M, and this considerably impaired efficiency. First, contra-rotating propellers were used, and the propeller gearbox was very weak. Problems with this gearbox quickly led to the redesign of the drive train to eliminate the contra-rotating feature and to use single-rotation propellers. This further reduced the efficiency of the propulsion system.<o:p></o:p>
<o:p></o:p>
The XB-35 was designed to use four of the then experimental Northrop Turbodyne gas-turbine engines, of approximately 10,000 hp each. This engine never attained flight status, so the decision was made to power the XB-35 with four Pratt & Whitnet R-4360 reciprocating engines of approximately 3,000 hp each. These engines simply were not powerful enough for an airplane of this size. The decision to rebuild the airplane as a jet solved the power problem.<o:p></o:p>
<o:p></o:p>
The YB-49<o:p></o:p>
<o:p></o:p>
I felt that the YB-49 was a beautiful airplane, and it was very smooth in flight. It eventually gave me a great deal of satisfaction, excitement and a heck of a lot of memories.<o:p></o:p>
<o:p></o:p>
(He then proceeds to discuss the YB-49 for several pages, but just these first two lines alone speak volumes for the contrast between how the XB-35 and YB-49 handled - between the XB-35, which never had enough power, and the YB-49 which had very near the amount of power that was originally part of the basis of the design.)

[deathfromafar]

Why not "What if" the model with Turbodyne powerplant power ratings and characteristics or "if" the R4350's with counter-rotating props had reached a decent performance benchmark? Kind of getting "bugs ironed out" in the world of FSX so to speak. :salute:

[warchild]

Thanks John. In all honesty, that little bit tells me exactly what i need to do next. Since its not accusimmed, theres nothing i can do about the vibrations from the gearbox and counter props, but i can do some other things..

A "jwhat If " is doable, but, as we have an actual plane, lets work with that first. in several ways, whats lacking in horsepower, is made up for in the wing itself. it'll still do 400 mph, but its gonna take you a lil longer to get there. It had a range of over 8000 miles with 16000 pounds of bombs on board, and 11000 with just fuel, and could fly to 39700 feet.

One thing ive noticed with this plane, is no mkatter WHAT speed your flying at, it feels slow and wallow-y. its actually one of the more charming realities of it and gives it a grace that is unlike anything i've ever seen in a plane..

For example, for the pic i just placed in the screenshot thread, i had to climb to almost 30000 feet, and I swear to god it was like i was never gonna get there, but it did, and then floated back down to earth for a nice landing at ksjc. Without a what-if, its an extremely unique airplane, and from an fsx perspective ( as we dont have to worry about threading ourselves in and around objects ) quite enjoyable.. A what-if, like i said, is doable, and perhaps i'll re-engineer the fde later on for that, but right now, we have something being built here, that doesnt need a what if and is every bit as much the icon today, as it was back then :)
Pam

[warchild]

Therer were at least two major drawbacks on the yb-49 that i've read so far. the first, was the engines overheating due to lack of ventilation, the second was the stall characteristic. The YB-49 didnd have engines to act as a tail lane, SOO, they added little finlets that you can see in the pictures of it, but they did little to help in any case. What was found and sadly realized was that in a stall, the YB-49 had a tendency to stay nose up and rotate backwards letting the weight of the engines drag it down like a guilotine. At some point it would lose stability and become even nmore uncontrollable.. Northrop themselves posted a warning to not stall this aircraft. The Army didnt listen, and Glen Edwards died from it.. In their final report, the Army credited the YB-49 to find the country it was headed for, but to not be able to do anything once it got there because it was so unstable that it was useless..

Designed for use with props, the flying wing was at its best with prop engines in it. It was far more stable than the jet ( but that isnt saying a lot ), and had that federal gearbox been better, it would have proven itself worthy of the research needed to get the turbine running correctly..

I've talked with piglet on this a bit, and we've decided we're making it real. I'll do a higher powered version of it as well for comparrison, so basically you'll be getting two planes in one package :)..

[Sundog]

I tried sending these to Piglet, but I don't know if he received them. You should find these useful if you don't already have them. I don't think you'll need the last one, but I included it for the hell of it.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040085365_2004089091.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092703_1993092703.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092792_1993092792.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092797_1993092797.pdf

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050028614_2005019353.pdf

[warchild]

Awesome sundog. Thank you..
I'll be digging into these full course in a few minutes after this check flight..

I got to thinking about the conversation directly above and, one question stood out in my mind before any others.. Why the counter rotating props?? Why would a company use them. They're expensive, finniky, maddening and I swear their always out to kill you, so why use them at all??
Thats when i recalled reading that as soon as they changed to a single four bladed prop the performance was so bad that the project was almost immediately scrapped. It could barely get off the ground.
You usecounter rotating props when there isnt enough thrust. Doubling up on the number of blades wont double your thrust, but it will take it to almost two thirds again what it is with four blades, so instead of an actual 12000 ( 14000 in our case ) horsepower, you have an augmented 20000 ( 25000 in our case ) of well, virtual horsepower ( for lack of the proper terminology.. Sucks being self taught some days )

Considering the plane was designed for fourty thousand horsepower, 25000 aint half bad.. ( waits for the joke to be gotten ). Its still underpowered, but not nearly so bad as it first appears..

Pam

[Sundog]

Counter rotating blades make controlling the aircraft simpler, since the gyroscopic effect of the propellers turning cancel each other out and they make more efficient thrust. When you have a single prop, a lot of energy is lost due to the "swirl" of the airflow behind the propeller disk. That swirl is wasted energy. The counter rotating prop re-straightens the flow out, regaining much of the lost energy. Of course the penalty is higher weight, complexity, and cost.

It's a matter of doing the trade studies to see how much it benefits the mission profile. It was obviously a benefit to the Seafire Mk.47, among others.

[Gibbage]

This is from what I recall the test pilot of the 35/49 telling me in an interview at Chino a few years hack. The 35 was a lot more directional stable then the 49. You will note that they even went so far as to put 4 fins on the 49. This was due (This is the pilot talking, not an engineer) the props "acting as a rudder". I dont know about the props, but the coweling was rather big and had a lot of surface area! Take it with a grain of salt as this was the pilots words, and it was a good 50 years since he was behind the stick in one!

[warchild]

This is from what I recall the test pilot of the 35/49 telling me in an interview at Chino a few years hack. The 35 was a lot more directional stable then the 49. You will note that they even went so far as to put 4 fins on the 49. This was due (This is the pilot talking, not an engineer) the props "acting as a rudder". I dont know about the props, but the coweling was rather big and had a lot of surface area! Take it with a grain of salt as this was the pilots words, and it was a good 50 years since he was behind the stick in one!

I think your right, and i believe he most likely meant the cowling although he called the entire unit the props.. Several tests were done on the wing to determine the best angle for the prop shaft and its effect on stalls spins and drag. the resulting angle provided the best performance with the greatest safety. Having them in line with the wing would have of course been much more beneficial to over all performance at lower altitudes, but it seriously bent the safety factor.

[CWOJackson]

I see some great things coming from this new team. I'm watching this project with a good deal of enjoyment.

[warchild]

heh. thanks chief. I gotta admit that i'm enjoying working on this plane. The information is either completely lacking, or its way over the top of my head and making me scramble to learn new things. I love it..
I started with using what i knew of the YB-49 and that got us in the air and steerable ( ok, maybe steerable is an overstatement ). now i'm gonna be going through the NACA tests results in the pdf's above and start narrowing it down. I made the decision last night to restrict the power to 3000 horse last night as it will be easier to be on target with all the other values if i do that. i can always up the power later, and still be on target..
:) . it'll be good..

[lazarus]

The -35 was more directionaly stable than the -49, the fins added to the -49's to compensate for the missing props 'keel' area. Both aircraft suffered from labour shortages, the airforce starving the program of materials, not delivering assorted GFE. No, no, not 'girl friend experience' whatever that is. 'Goverment firnished equipment' that was specified by Northrops as essential to the operational aircraft , notably an integrated yaw damper/autopilot/bombsight. Northrop flat out said to the airforce at the start words to the effect- It'll be a crap bomber without it. So much politicking, in fighting, and lobbying went on around the wings, 'twas astounding they ever flew at all.
Thanks for the updates, Pam.

[warchild]

Thanks Lazarus..
Yeahh, Jack had made some enemies in high places or at the least, couldnt get past their favoritism for loughead ( lockheed ). not much different than today really. Also, Jacks dedication to developing unconventional aircraft, wasdnt winning him any points with the military. my guess is that the government simply tossed whatever they had at him and told him to lump it or leave it. Oddly, they did the same thing with the supercharger of lockheeds P-38..

I have a quandary.. I was out flying this thing at 138 mph last night. Now, I fly a lot of planes slow, i mean heh, i like impossible air strips right?? but, 138 mph in this bird is one of the most excruciatingly painful things i've ever forced myself to do. I came south over san fransisco bay and made a right at oakland international heading for SFO.. some eternity later, I actually noticed that the runway really WAS getting closer.. However, the runway was till an eternity away.. I honestly am beginning to think that i've found the source of all the pilots exasperation's. this thing FEELS slow.. nothing about this plane is immediate. everything is incredibly graceful ( which really catches you up when landing as it doesnt like to slow down ( typical Northrop ) ) And too, I couldnt help but think about flying 11000 miles at 138 mph in this plane. 30 hours? Torture would be preferable..
Now, Tim wants this real; I want this real; You can still get 8000 miles at 390 mph. But, aw hell, i'm not even sure of the question i'm asking.. i want this to be real, and yet, i really want you folks to be able to really enjoy flying it because it really IS fun to fly. I guess i'm just being nervous..

So far, the plane will lift itself off the ground without flaps at 133 mph. It immediately assumes a nose high position ( normal for a wing ) and then begins to settle down. It takes aboyut three minutes for the up down pitching to stabilize ( the real plane took four ) after which, its like nothing ive ever flown before.. I wouldnt exactly take this canyon diving. With 157 feet of wing, it isnt the most maneuverable plane in the world, but it handles surprisingly well.
Stalls will be unique.. The NACA had a hell of a time with stalling this thing. They moved the CG about a dozen times and each time the stalls got weirder and weirder.. Most of them were close too if not unrecoverable, and required the opposite reaction from the pilot than most pilots are accustomed too ( rudders turned INTO the stall, DONT touch the power )..

I have the CG set at NACA's solution point which is 27.5% MAC, or about ten feet back from the leading edge.. This keeps the plane from rolling backwards on its tail when power is applied and provides for neutral trim at 360 mph. i dont know if the trim is too the books but heh, this is only day four of production :) ..

[warchild]

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..

[warchild]

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

[JohnC]

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..

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.

[warchild]

:)

50034

[warchild]

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.

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 ).

[lazarus]

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!

[warchild]

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.

[warchild]

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??

50053

[Sundog]

I'm assuming he is referring to the CL-215 firebomber.

[lazarus]

I'm assuming he is referring to the CL-215 firebomber.
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!

[warchild]

::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/50206334/1948-Report-No-HB-18-Pilot-s-Handook-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

[Roger]

Thanks for the updates Pam...this is a really interesting project:ernae:

[Sundog]

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.

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.

[warchild]

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

[warchild]

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.

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..

[warchild]

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

[TeiscoDelRay]

Anything new?

[warchild]

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.

50316503175031850319

[roger-wilco-66]

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

[warchild]

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

[warchild]

Hey Tim?? are you receiving my emails?? Have sent ypu a couple but no replies so i was getting worried..
Let me know..
Pam