Focke Wulf Fw200-A Condor

Very pleasing results for a completely amazing experiment!

Hello Ivan,
Thank you very much for your work. As far as I can see from your comparison chart the new results are very pleasing indeed!

It is completely amazing that this whole experiment has been possible with the resources available in CFS1 - and commendable that you actually found out how to do it!

One thing I always find fascinating with things in general, is to get something to do something for which it was not really made!
I once substituded the burnt out bread-machine motor with three washing-machine-pump motors driving a washing-machine belt installed outside the Breadman, running the belt around the original rotor motor through a cut in the housing. The computerized control unit still governed the whole kneading process! Anyway...

The slight increase in performance from S.L. to CA is negligible - it shows that the new engine is not a "Monday engine"! Trying to get it down a bit will also drag high altitude performance down, so I doubt that it will be a good maneuever.

I was never worried about the higher RPM - I had expected that anyway with a 2-pitch position manual propeller, due to the absence of a governor. I take it that the new .air file still needs the type 2 propeller, and not type 3 in the .air file.

The shift point is also no problem - the real propeller required a manual shift into high anyway. This would be done during initial climb a bit after wheels and flaps were tucked in, possibly around 150 mph. The fact that it does so automatically at 207 mph could be interpreted as a fail-safe mechanism to protect the engine from over-revving, so it´s fine by me the way it is now.

Thanks for your explanation of the new situation. I can more or less understand it!

I´ll try out the airplane with high pitch at 30 then. When I went for 35, it was already with the 9.7 ft propeller, but I didn´t know enough to see the benefits of narrowing the difference between the two pitches.

OK, the postman has just delivered the 4 new propellers in his van, and my technicians are unpacking them. They´d already read the descriptions and are quite excited about mounting them to try them out later in the morning!

I´ll tell you how it goes!
Cheers, and thanks very much again!
Aleatorylamp
 
Hello Aleatorylamp,

I hope it works out for you.
As I mentioned, it could use a bit of fine tuning, but the last part is very time consuming for smaller and smaller gains.
Note also that this time it isn't just the propeller tables.
I restricted changes just to the Power Coefficient Table (512) to leave room for more fine tuning for efficiency.
It turned out not to be necessary.
The Engine Torque / Efficiency Graph is pretty substantially modified and with any other tuning will need to be slightly modified again.
I can see room for improvement there because right now, the graph does not cover the entire RPM range.
It only goes up to 2150 or so. Maybe I will play with it some more if I have time.
Today is expected to be very busy.
Even the Coefficient of Drag on this Flight Model has been altered.

I suspect that some of the differences in results may be due to differences in our testing protocols.

I suspect that with the changes I made, the Climb Rate will be quite a bit higher and the Service Ceiling will be a touch lower than it was with the Constant Speed Propeller.
I actually tested neither of those.
I also did not test cruise conditions and throttle settings.

Do let me know what you get when you test things.
Be careful about altering things because a lot of variable are very finely balanced and changing one may affect things where you do not expect, especially since performance figures are not with a consistent RPM.

- Ivan.
 
Hello Aleatorylamp, Hubbabubba,

I actually expect to be very busy over the next few days.

Anna Honey left for a business trip very early yesterday morning.
She will be gone for a few days which means I am the single parent.
She actually got to her hotel well before Noon time and since the room was not ready (checkout is at Noon),
she decided to climb Mount Royal and take a few pictures and send them to us.

Gotta Run.
- Ivan.
 
Adjustments turning out perfectly.

Hello Ivan,
I hope you will be able to enjoy the weekend all the same.

I´ve just done some more exact testing, and as you said just now, there WAS room for a slight improvement
in order to get performance from S.L. to CA down slightly, without negatively affecting altitude performance.

Adjustments to this respect went very well, involving a very small Torque reduction and a very small Drag increase.

I had expected cruise speeds to fall into place rather in the same way as before, but they did so with less
horsepower and at lower RPM, which was very interesting! This was, of course, thanks to the more efficiently
built propeller!

Then, you said RoC would increase a little - all the better, as that was a little low before. At max. continuous
cruise it is now very well able to maintain the specified maximum RoC, and the propeller automatically shifts into
low pitch. It´s working incredibly well.

So, it´s all quite excellent!! My compliments to your propeller department!
Cheers,
Aleatorylamp
 
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Hello Aleatorylamp,

Are your numbers matching up well with what I posted?
I know if you wait long enough, the speeds will increase about 1-3 MPH but I only allow for a certain period of no increase before I record the value.

I am somewhat surprised that you believe the low altitude performance is too high.
As you can see, my numbers (possibly with a protocol different from yours) is only about 1 MPH higher than what you had labeled as "Max. Speeds: OK!"
in your performance document.

I was thinking that it would be very useful to program about three more gauges just for testing purposes:
Advance Ratio
Power Coeffient
Altitude Hold (because the Autopilot seems to wander a lot)

Regarding Climb, actually I think it will increase pretty substantially and be at a slightly higher speed from looking at the graph changes. Let me know if I am correct or not. There are many factors I am not taking into account.

- Ivan.
 
Hello Ivan,
Because I remembered your way of testing ("if it doesn´t change in 15 seconds, do the next"), that always left room for one or two mph more, I did the more exact tests I mentioned in my previous post. Results were as I expected, 2 or 3 mph higher, and also higher Hp.
This meant that I had enough leeway at altitude to reduce performance slightly, and got very close to the values my original performance document. Max. speeds are in most cases only marginally lower.

Changes to the .airfile, in case they could be of interest to you:
>Engine torque: 0.4945, end-drop 0.475
>Zero Lift Drag: 56
>Induced Drag: 2157
Note: Maybe the Induced Drag value lowered from 4157 will also help the plane to lose speed on approach.
Anyway, I had to lower it because lowering Zero lift Drag by 1 would have required a much higher
Induced Drag, making slow-down even more difficult.

Newly adjusted Max. Speeds: all at 30 pitch
__300ft: 226.1 mph, 720 hp, 2062 RPM
_5900ft: 244.0 mph, 764 hp, 2224 RPM
_8500ft: 242.4 mph, 685 hp, 2204 RPM
_9800ft: 242.2 mph, 650 hp, 2197 RPM
12500ft: 240.8 mph, 572 hp, 2171 RPM
15000ft: 239.3 mph, 510 hp, 2147 RPM
19700ft: 236.4 mph, 414 hp, 2113 RPM

Should you be interested in the cruising speeds, here they are:

328 ft:
Cruise: 200.0 mph, 0.95 ATA, 476 hp, 1801 RPM
Eco-Cruise: 186.0 mph, 0,88 ATA, 381 hp, 1671 RPM
3280 ft:
Fast Cr: 208.1 mph, 0,92 ATA, 497 hp, 1881 RPM
Cruise: 197.4 mph, 0,87 ATA, 420 hp, 1777 RPM
Eco-Cruise: 186.2 mph, 0,80 ATA, 340 hp, 1660 RPM
9800 ft:
Cruise: 199.8 mph, 0,71 ATA, 342 hp, 1777 RPM
Eco-Cruise: 191.2 mph, 0,68 ATA, 303 hp, 1705 RPM
12500 ft:
Fast Cr: 226.9 mph, 0,80 ATA, 475 hp, 2039 RPM
Cruise: 217.0 mph, 0,74 ATA, 406 hp, 1939 RPM
Eco-Cruise: 208.1 mph, 0,68 ATA, 377 hp, 1855 RPM

The RoC is also amazingly accurate at 1.1 ATA with a constant 1185 fpm (Specs say 1200 and 160 kph for the heavier but slightly more powerful Fw200-A0 units, so for this unit spec would be 170 kph). Climb starts with 550 Hp, the spec number for continuous power, and then goes up to above 650 with altitude.

Initial climb tests to 1000 and 2000 meters were just above the 2.6 and 5.9 specified minutes, giving 2.75 and 6.3 minutes, but I have to repeat them just in case. At full power of course RoC is much higher, and takes considerably less time: 2.25 and 5.5 min.

Well, it looks very, very good indeed, wouldn´t you say so too?
Cheers,
Aleatorylamp
 
Hello Ivan,
Regarding your idea of the 3 new gauges for testing purposes, it had occurred to me that an advance-ratio and a power-coefficient gauge could come in handy not only as a test gauge, but also as a panel instrument. I wonder if they´d exist in reality...
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Just got back from Doctor's Office.

I suggest you go back a bit and look at the balance between Induced Drag and Zero Lift Drag.
This is what I commented about much earlier and it seems to have gotten worse.

A reasonable number for Induced Drag / Oswald Efficiency would be somewhere in the range of 6000 to 8000 or so.
The stock P-51D Mustang would bleed too little speed in maneuvering because its value was about 4800 or so and your parameter is even lower than that.

By the way, 300 feet altitude isn't really Sea Level, so realistically, the speed should be a couple MPH higher there than what you are getting. This is not the IAS to TAS correction.

I wonder if anyone else has ever tried to simulate a two-pitch propeller in this manner?

- Ivan.
 
Hello Ivan,
My reference to S.L. in the case of the Fw200 specs really does not mean S.L. but is effectively 300 ft, as performance specs are given for 300 ft. ...the same way as you would sometimes say 500 ft for American or English models, really meaning S.L.

Update: Correction. OK, I´ve seen what you are getting at!
The only thing that would be effectively S.L. is 720 hp take-off power, which means it would then go up to 721 Hp. at 300 ft.
It was very difficult to test this, keeping the plane flying so low. Coming down with 720 Hp from 300 ft, at 160 ft, power was still 720 hp, but then at 100 ft, it suddenly went down to 719 hp, and speed went down 2 mph.
Further down, it was actually at 718, and speed was another mph lower.
So: I´ll put in 722 hp for 300 ft then, and speed will be 226.8-227.1 !

OK, thanks for the tip on the Oswald factor. I´ll just put in one unit less Zero Lift Drag, and increase the Oswald Factor to 6000 or so, or whatever I need to maintain performance. Just reducing Drag by 1 unit will increase Hp very slightly.

I was testing RoC to 3000 and 4000 meters just now, at about 92% throttle with 1.1 ATA, and it fits specs rather nicely as well!

I hardly think anyone has done anything like what you´ve done, making a 2-pitch manual propeller for the Simulator!
Think of how many models this propeller can be useful for, starting with the Lockeed Model 10 Electra, and the Hudson, and the 2 derived from the Lockheed Hudson, i.e. the Ventura and the Harpoon.

Great stuff!
Wow...
Cheers,
Aleatorylamp
 
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Hello Aleatorylamp,

There are actually formulas for doing the altitude to sea level conversion / density altitude, etc.
You don't need to do it experimentally.
As you have noticed, this flight model is hard to test because it isn't "stable" or "predictable" in many ways.
That is why it was so hard to adjust performance: Once you change one number, a lot of other things change.

Aleatorylamp said:
I was testing RoC to 3000 and 4000 meters just now, at about 92% throttle with 1.1 ATA, and it fits specs rather nicely as well!
Click to expand...


What airspeed are you getting for best climb?

Aleatorylamp said:
I hardly think anyone has done anything like what you´ve done, making a 2-pitch manual propeller for the Simulator!
Think of how many models this propeller can be useful for, starting with the Lockeed Model 10 Electra, and the Hudson, and the 2 derived from the Lockheed Hudson, i.e. the Ventura and the Harpoon.
Click to expand...


Of the aircraft you list here, I believe only the Model 10 Electra had a Two-Pitch Propeller. The rest were the typical War Time Constant Speed stuff.

- Ivan.
 
Hello Ivan,
OK, I see. Of those, the Electra only, as it was older and not war-time.

Now, upping the Oswald factor to 8000 to adjust the reduction of Zero Lift Drag by 1, of course reduces high altitude performance a bit too much for my liking. Not good. In addition, restly performance is now almost the same as in your newest .air file.

So... Much Ado about Nothing! I´m leaving it as it was with the .air file you sent! The fine adjustments I wanted are just not possible. ...and probably irrelevant anyway.

The best RoC of 1185 fpm was at 185 mph, at about 2000-4000 ft. At one point it was just between the two pitches. I found that most of the time low pitch was being used. Forcing high pitch gave one or two mph lower. I suppose this would depend on altitude as well, and as Hp goes up, pitch would change to high, but I wasn´t paying much attention to pitch all the time.

Climbing times to the 1,2,3 and 4-thousand-metre reference heights, as I mentioned before, also tallied well, which leads me to believe that the information about 170 kph being the typical climbing speed would rather refer to an economic-cruise-climb, if anything.

Well, all this and that being cleared up, it´s bed-time now!

Cheers, and thanks for your feedback and support!
Good night!
 
Hello Aleatorylamp,

I am not even sure where to begin here....
As usual, I get the impression that your goal and mine are not the same.
I try to get within a couple MPH of where I believe the performance SHOULD be.
My preference is to "best" match the performance curve while knowing that it is highly unlikely that I will match more than a couple points exactly.
It seems to me that you are going for within 1 MPH and while I believe that is possible at whichever point you pick, you will be further off at other points.
Also keep in mind that for most of these aircraft, there was no autopilot or the autopilot of the time was very primitive.
If you really want to simulate those conditions, try flying a speed run WITHOUT autopilot and see how close you get.
I am betting you will be at least 2-3 MPH too low so if I get 2-3 MPH too high WITH autopilot, then I am quite happy.
Besides, even with two consecutive aeroplanes off the same assembly line, a couple MPH is within the range of variations.

So with that in mind, how much difference does 1 point in Zero Lift Drag make to your maximum speeds?
Is it within the range of acceptable variations?
If it is, then why tune Induced Drag all the way up to 8000?
I would have figured 6500 to 7000 would be quite sufficient. We can discuss why I believe that if you wish.

That was the philosophy discussion for today.
.....or maybe it wasn't....

Aleatorylamp said:
So... Much Ado about Nothing! I´m leaving it as it was with the .air file you sent! The fine adjustments I wanted are just not possible. ...and probably irrelevant anyway.
Click to expand...


Impossible is a pretty harsh term considering what we are discussing.
A couple weeks ago, where we are RIGHT NOW would have seemed to be "Impossible" and it obviously was not.
I KNOW there is some fine tuning that still needed to be done and with this adjustment of just High Altitude performance, YOU already know how to do it.
(Remember the deal about tuning both Torque and Friction down at the same time that was discussed in the Engine Performance Tuning thread and in the Flying Swallow thread?)
The only problem with doing this here is that adjusting Torque will also adjust RPM and of course that affects Advance Ratio and Power Coefficient....
Now THAT is how the Altitude performance can be improved.
As far as very very fine adjustments to speed, think about adjusting the Propeller Efficiency graph down a bit.
With a double precision floating point value, you can knock it down 0.00001 % at a time if you want and that is a VERY fine adjustment (and nearly meaningless for effect).

Aleatorylamp said:
The best RoC of 1185 fpm was at 185 mph, at about 2000-4000 ft. At one point it was just between the two pitches. I found that most of the time low pitch was being used. Forcing high pitch gave one or two mph lower. I suppose this would depend on altitude as well, and as Hp goes up, pitch would change to high, but I wasn´t paying much attention to pitch all the time.

Climbing times to the 1,2,3 and 4-thousand-metre reference heights, as I mentioned before, also tallied well, which leads me to believe that the information about 170 kph being the typical climbing speed would rather refer to an economic-cruise-climb, if anything.
Click to expand...


185 MPH sounds a bit too high to me. You really want to stay around 0.8 Advance Ratio to catch the peak there.
If it makes no difference between High pitch and Low pitch, you are going too fast.
The aeroplane should not be climbing best in High Pitch.

Be careful about concluding that 170 KPH is wrong. It is more likely the AIR file is wrong. I was figuring the best climb speed was going to be too high anyway but you can adjust that pretty easily by changing the Propeller Efficiency graphs.
I don't like doing that part because it needs many edit & test cycles to get right.

I suppose that is quite enough lecturing.
It is getting late here as well.

- Ivan.
 
Hello Ivan,
Hmmm... so all in all, with all the work that has been involved, and in view of the good quality of the results, I can´t really say much more than that the experiment has been much more successful than either of us would have expected a while back.

As I see it now, the .air file you sent is highly satisfactory, and in view of what you say in your last post, even my slightly modified version of it would qualify satisfactorily as well, but although its slight performance reductions could arguably be within limits, as they were not exactly needed, they weren´t really correcting anything, so the concept for their application was not correct.

In conclusion, the new .air file is finished then, and I´ll be uploading the Condor with it.

It is an incredibe new asset to have a two-pitch propeller for this aircraft.
In effect, it´s an incredible new asset for CFS1 in general!
With it, the model has gained a lot, and with the new multi-engine instruments, even more so. The SCASMed interior cockpit addition has made its contribution too, so compared to how the model was a few months back, there is a high increase in quality, which is very pleasing.

I´m going to try and give the L/R fuel gauges a more "un-Extra-300" look before uploading though!

Would you have any other suggestions in any respect before I upload the model?

Thank so much again for all your efforts in the production of the propeller and also in the sequence of explanations that came along with the process, like the last bit about avoiding the high Induced Drag - and the previous bit about avoiding a too low one of those as well !!

Cheers,
Aleatorylamp
 
Propeller pitch gauge?

Hello Ivan,
Idea:
Given that the new 2-Pitch position Propeller can be used manually, also haing a fail-safe mechanism to go into high pitch to prevent engine over-revving (I think this also happens when "manual adjustment" is selected in Propeller Record 330), do you think it would be practical and/or useful to have propeller pitch gauge on the panel? In other words, would your Gauge Department feel like building one?
It´s just a thought, and maybe it´s ridiculous because I think those things don´t exist in reality. But, when the pitch levers are on low pitch and the propeller goes into high automatically, there´s no way of telling. With a gauge the pitch position would be more noticeable.
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Any more changes you ask?
I really don't know. (At least not all the changes)
I was not really trying to check out the flight model for anything other than the level speeds, engine power and propeller pitch changes and I didn't really spend time to adjust the pitch changes.

You obviously were dissatisfied with something earlier and perhaps that needs to be addressed.
You have built many more aeroplanes than I have, so by now you probably have some established standards.
I know mine keep changing to get stricter.

Here is what I DO know assuming you are starting from the AIR file I sent to you:
1. Adjust the Induced Drag / Oswald up to 6000 or so.
That should bring down some of the "Excessive Speed".

2. For optimum performance, Propeller Pitch change should ALWAYS happen at around J=0.85 to about J=0.9.
Plot the Propeller Efficiency Table in a spreadsheet and you will see why.
I was thinking about this yesterday and here is what I would do:
The problem with doing this is that your Power Coefficients at full throttle were pretty close together at around 0.058 to 0.060 or so with one notable exception: 300 feet.

Actually the number is pretty low below about 3000 feet at around 0.048 which is pretty much what you have for maximum cruise conditions.

So what you want to do is calculate your Power Coefficients at Full Throttle at each significant altitude and also cruise settings at 12500 feet and below.
What you want to do is change Record 512, the Power Coefficient Table so that the shift point at full throttle is around J=0.80 to perhaps J=0.85 AND make sure that the shift point at cruise power happens before maximum cruising speed (perhaps around 200 MPH or so).
At that point, I believe you will just have to accept that at full throttle below 3000 feet, propeller pitch changes will behave more like the cruise condition.

I think that can be done but I haven't recalculated all the numbers to make sure after the last tuning exercise.

- Ivan.
 
Performance is perfectly satisfying.

Hello Ivan,
No, no, no, no, no, no, no... I am perfectly happy with the 2-pitch propellers, with how they work, and with the Condor´s whole performance, i.e. during Take-off, at 300 ft, at Critical altitude, during Climb, and any other altitude all the way up to ceiling.

As I said, I´m going to use the .air file you sent me as it is for the upload, because it does indeed work perfectly well!

After your clarifications on S.L. Power and Speeds compared to how these are at 300 or 500 ft, and given the marginal differences elsewhere along the curve, my dissatisfaction has completely vanished!

When I was asking for suggestions it was nothing to do with performance. You have already explained a large number of things that could be undertaken to get marginal improvement, but the differences are will be negligible and most probably not worth while, at least for me. Thank you for the further details you sent on how to do some even finer tuning, but I´m afraid that I´m not into such depth.

Oh!, and thanks for the tip on bringing the Oswald Factor up to 6000 to get rid of some of the excessive speed. I will do that!

My question was rather whether any other aspects had to be dealt with before an upload.

I have conveniently mentioned the 2-pitch propellers and also the RPM and Boost gauges that you programmed, in the Presentation Text for the upload, as well as in the Readme inside the aircraft file.

The Dp file is done, without weapons, the scrape points are adjusted, and I suppose my thoughts about a gauge telling the pilot what propeller pitch is in use, are unnecessary.

So, once I complete the Checklists with a useful comment on the 2-pitch propellers, the Condor will be ready for upload.

P.S. Here are the new max. speeds corresponding to the change in the Oswald Factor to 6000: Very pleasing!
__300 ft: 229.5 mph, 726 Hp, 2072 RPM
_5900 ft: 247.6 mph, 766 Hp, 2230 RPM
_8500 ft: 246.5 mph, 687 Hp, 2211 RPM
_9800 ft: 245.3 mph, 649 Hp, 2200 RPM
12500 ft: 243.5 mph, 573 Hp, 2173 RPM,
15000 ft: 240.8 mph, 510 Hp, 2148 RPM
19700 ft: 236.7 mph, 417 Hp, 2113 RPM

Cheers, and I´m terribly sorry about the misunderstanding, and about making you explain so much again!

Aleatorylamp



 
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Panel details

Hello Folks,
In view of the success with the 2-pitch propeller, I decided to put in a bit more detail into the panel bitmap.

I had another cockpit-photo showing the sunshades strapped to the canopy spars, which fortunately also had a bit more surface-detail, so the result came out quite well. The perspective was a bit different, but rotating the necessary cut-outs and filling in some pixels did the trick.

Then, the dial and needle bitmaps of the altered FSFSConv fuel, amps and vaccuum gauges now match the rest a bit better. Here´s a screenshot of the panel. Now I´m just finishing the texts for the upload.

Cheers,
Aleatorylamp
 
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Hello Aleatorylamp,

No problem regarding help.
I am glad we have one of the old prop-liners back in service.

There is still plenty of room for experimenting with the two-pitch propeller, but at the moment, my Technicians are working in the paint booth.

Anna Honey should be back in town by tomorrow evening.

- Ivan.
 
Future use for the 2-pitch propeller

Hello Ivan,
Make sure everyone´s wearing masks and the ventilation´s on full blast!

Regarding room for further experimentation on 2-pitch propellers, there´s a convenient project on the drawing board for the (near?) future, an Electra Model 10A, with its 450 Hp P&W-985 Wasp Junior SB radials. Amelia Earhart´s Model 10E had 600 Hp R-1340-S3H1 engines that appear to have been equipped with CV propellers, so that would be a later derivation with more modern props.

Update:
Of course, I realized that such a large difference in performance, from 720 Hp down to 450 Hp, required in the first place, a different propeller diameter, to maintain blade velocity at lower power, so that the graph tables could maintain their effect.

I found a reference to the 10E as having a 9 ft, 3:2 reduction-geared prop for its 600 Hp at 2250 RPM, giving the Electra 10E a maximum speed of 220 mph, and that was a help. Initial trials with the .air file gave good approximations, which however I didn´t pursue, as this was not the engine for the 2-pitch propeller.

Then, with the reference of the 450 Hp engine as running at 2300 RPM with a direct-drive prop, giving the 10A a maximum speed of 202 mph, I supposed that 150 Hp less could hardly have been with the same propeller. Experimenting with the diameter, I finally arrived a very good result with an 8.18 ft propeller and some torque graph and drag parameter adjustments: 202.4 mph with 450 Hp and 2309 RPM.

The Model 10A is running only 0.4 mph and 9 RPM fast. As you had already recommended, I did this without altering the Friction Graph. Would you say this qualified as a practical and valid application of the same type of Hamilton Standard Propeller for a smaller twin?

As soon as I start building the model itself, I´ll open up a new thread for it.

Good luck with the Ki-61 artwork!
Cheers,
Aleatorylamp
 
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