Knights of the Sky Foundation

[Holtzauge]

And the German Baubeschribung for the Fokker Dr.1 from November 1917 states the engine used as a "110 PS Le Rhone" delivering 130 PS at 1200 rpm. Converting 130 PS to hp gives 128 hp. Then we have the English Air Board data sheets from 1917 that states the "110 Le Rhone" as delivering 137 hp at 1250 rpm in the Camel and then inexplicably 126 hp at 1250 rpm in the 1.5 Strutter. So not an altogether easy task to make any sense of "110 hp Le Rhone" in isolation unless you know which "110 hp Le Rhone" (9Ja, 9Jb, 9Jby, aluminium or steel pistons etc.) is meant in each particular case......

[nobuttons]

Flying Circus (and IL2) noob here, but I am super impressed by these efforts to recreate historical aircraft and learn from them! Hats off to you! 

 

As VR sim pilot I have a couple of questions that I think this group might be uniquely positioned to answer. For context I have a complete sim-pit for DCS with sim-shaker for feedback and immersion, however moving to the open cockpits of FC I was immediately curious if I could provide even more immersion, and even more feedback by using fans to simulate airflow in real time?

 

Getting telemetry out of IL2 seems straight forward, and controlling one or more ducted electric fans seems straightforward. As a result I'm curious...

1. When in the cockpit flying around, how much 'wind' is actually felt by the pilot, and how much is deflected by the airframe, windscreens, etc? Is there any meaningful sense of wind, or is it mostly blocked? (I'm wondering how much I should bother in trying to simulate this if it's a meaningful part of the flying experience)
2. If you do sense the wind, how forceful is it? I am guessing it's not directly equal to the airspeed of the plane because it is disturbed by the airframe, but is it close, or is it a fraction? Has anyone taken one of those portable anemometers to measure the speeds? (I'm wondering if it's possible to approximate actual wind forces or whether it's going to be a scaled down approximation for feedback)
3. How much does it vary, and is it generally correlated with airspeed? Is it constant or gusty? (I'm wondering if the programming will be direct interpolation of IL2 telemetry or whether there will need to be additional logic)
4. In addition to airspeed does it vary any other meaningful ways? Do extreme aerobatic maneuvers  cause all sorts of wind directions, or is the thrust of the propeller over whelm other relative winds speeds even at stalls? (I'm wondering what else would need to be factored in)
5. When using rudder and pointing the aircraft off the axis of motion is that perceptible in the direction from which air is felt in the cockpit? (I'm wondering if it's be useful to use a matrix of fans modulated to produce stronger airflow from variable directions, or whether just modulating airflow from in front is all that is required)
6. Anybody know of anyone else trying something like this before?

Any insights would be greatly appreciated!

[Chill31]

20 hours ago, nobuttons said:

 

1. When in the cockpit flying around, how much 'wind' is actually felt by the pilot, and how much is deflected by the airframe, windscreens, etc? Is there any meaningful sense of wind, or is it mostly blocked? (I'm wondering how much I should bother in trying to simulate this if it's a meaningful part of the flying experience)

It will depend on the airplane. Big windscreens, SE5 for example, will block a lot of what the pilot feels. Little ones, like the Dr.I, do very little.  In the DR.I, the loudest sound is the wind noise.  I do feel a lot of the wind, but not all of it thanks to the windscreen.  

20 hours ago, nobuttons said:

1. If you do sense the wind, how forceful is it? I am guessing it's not directly equal to the airspeed of the plane because it is disturbed by the airframe, but is it close, or is it a fraction? Has anyone taken one of those portable anemometers to measure the speeds? (I'm wondering if it's possible to approximate actual wind forces or whether it's going to be a scaled down approximation for feedback)

It is forceful. Stick your head out of the window on the highway,  and that is about right. 

20 hours ago, nobuttons said:

1. How much does it vary, and is it generally correlated with airspeed? Is it constant or gusty? (I'm wondering if the programming will be direct interpolation of IL2 telemetry or whether there will need to be additional logic)

It does vary with flying speed, assuming you throttle down to slow down. Full throttle is a lot of wind!

20 hours ago, nobuttons said:

1. In addition to airspeed does it vary any other meaningful ways? Do extreme aerobatic maneuvers  cause all sorts of wind directions, or is the thrust of the propeller over whelm other relative winds speeds even at stalls? (I'm wondering what else would need to be factored in)

Not really. The wind from the propeller is quite strong.

20 hours ago, nobuttons said:

1. When using rudder and pointing the aircraft off the axis of motion is that perceptible in the direction from which air is felt in the cockpit? (I'm wondering if it's be useful to use a matrix of fans modulated to produce stronger airflow from variable directions, or whether just modulating airflow from in front is all that is required)

Yes! You can feel it noticeably on the side of your head.

20 hours ago, nobuttons said:

1. Anybody know of anyone else trying something like this before?

Any insights would be greatly appreciated!

 

[J2_Trupobaw]

I'm not sure if you can get telemetry out of Il-2, but from Chill says tieing fans speed to throttle axis and their balance to rudder may give general approximation?

[nobuttons]

There's a couple pointers here that look promising for telemetry...

The seat forcefeedback system I used and how they configure it to get telemetry from IL2 via UDP: https://dreamsimteam.blogspot.com/p/simshaker-wings-user-guide.html

Github project for telemetry from IL2: https://github.com/phartgames/il2simfeedback

[Guest deleted@83466]

Tacview must also be receiving telem.  EDIT:  or maybe not in IL-2, because it can only read the recording of parameters in the .trk file, after you’ve made a complete recording?

Edited July 16, 2021 by SeaSerpent

[nobuttons]

9 hours ago, Chill31 said:

It will depend on the airplane. [...]

 

This is fantastically useful! Thanks so much!

2 hours ago, SeaSerpent said:

Tacview must also be receiving telem.  EDIT:  or maybe not in IL-2, because it can only read the recording of parameters in the .trk file, after you’ve made a complete recording?

Yeah tack view does something different than open a UDP connection. SimShaker wings has a pass through mode I've discovered so getting data out is covered, now have to go parse it....

[Chill31]

So...on the speed front, it seems I cant get it past 105-106...I'm right at 1280 rpm.  My static run up is 1180.  I could potentially adjust the pushrods to try to sneak a little more power...

 

For now, enjoy this little gem...

 

 

[ST_Catchov]

[BMA_Hellbender]

14 hours ago, Chill31 said:

So...on the speed front, it seems I cant get it past 105-106...I'm right at 1280 rpm.  My static run up is 1180.  I could potentially adjust the pushrods to try to sneak a little more power...

 

Interesting. Would pushing the engine even further become less and less representative of how a real Dr.I would have operated in the field what with the lack of castor oil? Unless of course we're talking about Voss' Fokker F.I which used a French 120hp Le Rhone and actual castor oil. So the question I'm asking myself is how the Fokker D.VIII would then have performed with the same engine, but perhaps improved mineral oil and Voltol (rapeseed oil) to achieve higher static RPM than the Dr.I? We may simply be looking at top speeds reached on prototypes with different engines.

 

For the record: in the French Clerget-Blin 9B operating manual I bought there is only ever mention of 130hp at 1200 RPM. I think that anything beyond that is really up to the mechanic, and perhaps never readily achieved with French-built engines. So what we're thinking of a standard Clerget 9B found on the Camel is in fact a Clerget-Bentley 9B(f). It certainly explains the difference in RPM between the 1916 Sopwith Strutter (in RoF) and the 1917 Sopwith Camel (in FC and ex-RoF) which both use the 9B.

[Holtzauge]

@Chill31: OK, based on these latest results maybe there is an issue with the engine after all? I’m thinking that you now get 1180 rpm static on the ground but before as I remember you got 1220 rpm?

 

I guess it’s difficult to make a call on the latest speed you measured and if that is what the Dr.1 would do or not IRL but one thing I think that points in the direction that you are not getting the full power potential is the climb rate: As I understand it you are now getting around 1000 fpm at low altitude?

 

Now when it comes to climb rates I believe the historical data is better and more reliable than speed: Especially for the German planes since while a lot of German WW1 data only has “gef.” (required) not the “err.” (reached/measured) for speed (usually just blank), a lot of “Baubeschribung” data contains the “err.” for climb, usually based on barograph results making them reliable IMO, especially if we are looking at a “delta” between two altitudes.

 

While the Dr.1 Baubeschribung does not give climb speed from 0-1 Km altitude, the measured climb time from 1-2 Km is 2.6 m. This is roughly 1260 fpm meaning the climb rate from 0-1 Km should be even higher. Now it you are getting only 1000 fpm between 2000-3000 ft this sounds on the low side to me compared to the 1260 fpm measured between 3300-6600 ft in WW1?

Edited July 26, 2021 by Holtzauge

[ZachariasX]

Looking at the effort required to get most of that engine, if I had a sqadron of 12 aircraft, what would be the average number of flyabe aircraft snd what would be the average power output?

[Chill31]

8 hours ago, Holtzauge said:

@Chill31: OK, based on these latest results maybe there is an issue with the engine after all? I’m thinking that you now get 1180 rpm static on the ground but before as I remember you got 1220 rpm?

 

I guess it’s difficult to make a call on the latest speed you measured and if that is what the Dr.1 would do or not IRL but one thing I think that points in the direction that you are not getting the full power potential is the climb rate: As I understand it you are now getting around 1000 fpm at low altitude?

 

Now when it comes to climb rates I believe the historical data is better and more reliable than speed: Especially for the German planes since while a lot of German WW1 data only has “gef.” (required) not the “err.” (reached/measured) for speed (usually just blank), a lot of “Baubeschribung” data contains the “err.” for climb, usually based on barograph results making them reliable IMO, especially if we are looking at a “delta” between two altitudes.

 

While the Dr.1 Baubeschribung does not give climb speed from 0-1 Km altitude, the measured climb time from 1-2 Km is 2.6 m. This is roughly 1260 fpm meaning the climb rate from 0-1 Km should be even higher. Now it you are getting only 1000 fpm between 2000-3000 ft this sounds on the low side to me compared to the 1260 fpm measured between 3300-6600 ft in WW1?

I did not keegood enough track of static rpm in my initial runs because it ran so poorly.  Looking back, I am shocked I got it to run up at all. On top of that I was only referencing my 100 year old tach which probably has small errors in it.  (Jaeger tachs are not as nice as Morrell tachs)

 

I am curious about the season of their climb time. I lose a lot of climb 8n my RV-8 in summer vs winter. 

 

The only thing I could do to improve power output is reduce intake valve clearance.  I will check them. 

 

Otherwise, the engine is running very well. I can not be sure it isn't short a couple of horsepower though. Is it an average front line engine? My guess yes.

Edited July 26, 2021 by Chill31

[ZachariasX]

8 hours ago, Chill31 said:

I am curious about the season of their climb time. I lose a lot of climb 8n my RV-8 in summer vs winter. 

Neat aircraft! What engine did you install? Lycoming AEIO-320?

[Chill31]

4 hours ago, ZachariasX said:

Neat aircraft! What engine did you install? Lycoming AEIO-320?

IO-360 200 hp. They are amazing amazing airplanes

[SeaW0lf]

171km/h (plus) during summer is sweet, Chill.

 

I wonder what they did back in the days to tune the plane. If I recall correctly Carl Jacobs had two or three Dr.1s at his disposal until the end of the war, some of them with Clerget engines. His mechanic treated them like pets. McCudden on this regard was harsh on the squadron, being on top of everyone's plane. If I recall correctly, he demoted one of his men because the gun sight of his plane was misaligned.

[Holtzauge]

18 hours ago, Chill31 said:

I did not keegood enough track of static rpm in my initial runs because it ran so poorly.  Looking back, I am shocked I got it to run up at all. On top of that I was only referencing my 100 year old tach which probably has small errors in it.  (Jaeger tachs are not as nice as Morrell tachs)

 

I am curious about the season of their climb time. I lose a lot of climb 8n my RV-8 in summer vs winter. 

 

The only thing I could do to improve power output is reduce intake valve clearance.  I will check them. 

 

Otherwise, the engine is running very well. I can not be sure it isn't short a couple of horsepower though. Is it an average front line engine? My guess yes.

 

OK, did not know that the 1220 versus 1180 rpms were measured with different tachometers so difficult to compare then I suppose.

 

If you are planning more trials with the Levil BOM it would be nice to see speed and climb rate as a function of altitude and also a climb time chart. I'm putting together a speed/altitude chart (will post later) with simulated, factory numbers and Idflieg flight measurements and interestingly enough Idflieg and Fokker firm data bracket your flight test if I extrapolate that to higher altitudes. However, a few more data points at lower and higher altitude would certainly help if you plan to do that.

 

Regarding the temperature effects, maybe @ZachariasX has some input on this? IIRC then you have quoted stuff from flight manuals before and perhaps these can be used to gauge temperature effects or perhaps they only list things like take-off run depending on altitude and temperature? I did find some data on this in NACA report 171 by W S Diehl but as far as I can tell from that report the engine power drop is only a couple of percent going from 15 to 25 C.

[ZachariasX]

27 minutes ago, Holtzauge said:

Regarding the temperature effects, maybe @ZachariasX has some input on this? IIRC then you have quoted stuff from flight manuals before and perhaps these can be used to gauge temperature effects or perhaps they only list things like take-off run depending on altitude and temperature? I did find some data on this in NACA report 171 by W S Diehl but as far as I can tell from that report the engine power drop is only a couple of percent going from 15 to 25 C.

I would think so as well. For Lycoming engines (just to take a „normal“ unaspirated engine) is not much, IIRC as you say just some single % variation according to their manual. They also have a formula for getting the temperatue offset.

[SeaW0lf]

On 7/27/2021 at 3:33 PM, Holtzauge said:

but as far as I can tell from that report the engine power drop is only a couple of percent going from 15 to 25 C.

 

Air density due to temperature plays a factor as well.

 

At least in the Il-2 engine it gives you a couple miles difference from Summer (25ºC) to autumn (15ºC) if I'm not mistaken.

[Holtzauge]

52 minutes ago, SeaW0lf said:

 

Air density due to temperature plays a factor as well.

 

At least in the Il-2 engine it gives you a couple miles difference from Summer (25ºC) to autumn (15ºC) if I'm not mistaken.

 

Sure, there should be a difference. Question is still how much it should be? I don't know if @Chill31will do more speed runs but in parallel to the speed investigation, I'm going to try to dig up more on the climb rate and try to figure out how his 1000 fpm climb rate at low altitude compares to historical data.

[Chill31]

On 7/27/2021 at 2:33 PM, Holtzauge said:

 

OK, did not know that the 1220 versus 1180 rpms were measured with different tachometers so difficult to compare then I suppose.

Those were measured on the same tach, but the precision of the instrument is not perfect. French Jaeger tachs have some sort of clock mechanism inside which seems to be there to Mach the needle move and reset to zero.  Whatever its purpose...the result is that it has a tendency to jump above and below what I am assuming to the target value. Before I became anal retention about the exact RPM, 1220 is a high excursion that I've seen recently and was likely what I saw before. 

On 7/27/2021 at 2:33 PM, Holtzauge said:

 

If you are planning more trials with the Levil BOM it would be nice to see speed and climb rate as a function of altitude and also a climb time chart. I'm putting together a speed/altitude chart (will post later) with simulated, factory numbers and Idflieg flight measurements and interestingly enough Idflieg and Fokker firm data bracket your flight test if I extrapolate that to higher altitudes. However, a few more data points at lower and higher altitude would certainly help if you plan to do that.

I will try to do that this weekend.  

 

On 7/27/2021 at 2:33 PM, Holtzauge said:

 

Regarding the temperature effects, maybe @ZachariasX has some input on this? IIRC then you have quoted stuff from flight manuals before and perhaps these can be used to gauge temperature effects or perhaps they only list things like take-off run depending on altitude and temperature? I did find some data on this in NACA report 171 by W S Diehl but as far as I can tell from that report the engine power drop is only a couple of percent going from 15 to 25 C.

I made a standard atmosphere model in excel and 15 to 25 C is 3.6% power loss.  Living in Southern USA, humidity may be a factor as well.  We see 75-85% often, so I need to pay attention to that on the next test. How is humidity in France?

[ZachariasX]

3 hours ago, Chill31 said:

I made a standard atmosphere model in excel and 15 to 25 C is 3.6% power loss.  Living in Southern USA, humidity may be a factor as well.  We see 75-85% often, so I need to pay attention to that on the next test. How is humidity in France?

Depends, but if we take Paris (that is France by decree), you have some 72-82%, averaging 78%. Summers are dryer. It is more humid in northern areas due to the exposure to atlantic weather than in more inland areas in southern France like the Provence, where in summer air gets very dry and humidity drops to about 60% in summer from 70ˋs in winter.

 

I would think that local density altitude has a bigger impact than temperature alone.

[Holtzauge]

9 hours ago, Chill31 said:

Those were measured on the same tach, but the precision of the instrument is not perfect. French Jaeger tachs have some sort of clock mechanism inside which seems to be there to Mach the needle move and reset to zero.  Whatever its purpose...the result is that it has a tendency to jump above and below what I am assuming to the target value. Before I became anal retention about the exact RPM, 1220 is a high excursion that I've seen recently and was likely what I saw before.

 

OK, thanks for the details and good to know: Looks like it's difficult then to determine the engine state through the rpm since this can vary both during and in between measurement occasions.

 

9 hours ago, Chill31 said:

I will try to do that this weekend. 

 

Great! Getting some climb numbers would be good. In my simulation I don't have any problem getting numbers between any arbitrary heights but if you can, please try to get the times between even Km values, i.e. 1-2, 2-3, 3-4 Km (3280-6560, 6560-9843, 9843-13120 ft) altitude since this is what we have historical values for. I know you don't have an infinite airspace so I guess the higher altitudes are a no-go but I throw the numbers out anyway!

 

9 hours ago, Chill31 said:

I made a standard atmosphere model in excel and 15 to 25 C is 3.6% power loss.  Living in Southern USA, humidity may be a factor as well.  We see 75-85% often, so I need to pay attention to that on the next test. How is humidity in France?

 

Could you share how you do the calculations? Would be good to know since I don't really have a good method for this even for temp and certainly not humidity and density.

 

6 hours ago, ZachariasX said:

Depends, but if we take Paris (that is France by decree), you have some 72-82%, averaging 78%. Summers are dryer. It is more humid in northern areas due to the exposure to atlantic weather than in more inland areas in southern France like the Provence, where in summer air gets very dry and humidity drops to about 60% in summer from 70ˋs in winter.

 

I would think that local density altitude has a bigger impact than temperature alone.

 

Yes, I guess you need to take not only the temp but those other factors as well into account. Maybe Chill's excel can help out with that but in any case, any insight on this would be good info for me since I don't have a method for adjusting engine power as a function of these variables and can only generate data assuming 15 C standard atmosphere right now.

[Chill31]

The current issue of Warbird Digest has basically everything I can say about flying the Dr.I at the moment.  

https://warbirddigest.com/

 

Also, we are going to do something cool here in US in October 

 

https://gofund.me/e511e914

[Cynic_Al]

On 2/20/2022 at 9:14 PM, Chill31 said:

Also, we are going to do something cool here in US in October 

 

https://gofund.me/e511e914

 

Will someone be making a monetised video of the event?  If they do, I promise not to skip the ads. 

 

[Chill31]

On 2/23/2022 at 6:41 AM, Cynic_Al said:

 

Will someone be making a monetised video of the event?  If they do, I promise not to skip the ads. 

 

Haha most definitely! I intend to watch them on repeat for a bit!

[Chill31]

Headed off to fly a Sopwith Camel!  No Clerget on it, but it should still give me some good insight to the plane.  I'll post some.pics and videos with a flight report later.

 

What myths should I test?  

Edited May 5, 2022 by Chill31

[No.10_Ace_Ivo]

1 hour ago, Chill31 said:

 

What myths should I test? 

Snap rolls. ?

[BMA_Hellbender]

1 hour ago, Chill31 said:

Headed off to fly a Sopwith Camel!  No Clerget on it, but it should still give me some good insight to the plane.  I'll post some.pics and videos with a flight report later.

 

What myths should I test?  

 

Left turn vs right turn duration, top speed in level flight (what engine is on it?).

[1PL-Husar-1Esk]

1 hour ago, Chill31 said:

What myths should I test?  

How bad is adverse yaw , it's possible to do only aileron turn ?

[Cynic_Al]

1 hour ago, Chill31 said:

What myths should I test?  

 

If it isn't fitted with a rotary then all bets are off, in just the same way they were with your Lycoming-ed Dr1.

[Chill31]

22 minutes ago, Cynic_Al said:

 

If it isn't fitted with a rotary then all bets are off, in just the same way they were with your Lycoming-ed Dr1.

Thats just not true...having flown the Dr.I with a variety of engines on top of the years of aerodynamics I've studied, I can assure you, most of the handling qualities of the plane can be evaluated without a rotary.  

 

Evaluating performance (speed, climb, turn rate) will not be accurate.  Other aspects, like roll rate and stall behavior are things we can check.  Even turn rate will be fairly close, but is a function of excess power. 

 

 

[1PL-Husar-1Esk]

12 hours ago, Chill31 said:

What myths should I test?  

what is minimum speed to do a loop

[Chill31]

I just finished a couple of flights in the Camel, and it is really a sweet flying plane.  The idea that thin wings stall aggressively and cause wild spinning is just not true.  I really tossed it around (video still needs editing), and it handled it all so well! The Dr.I is a nicer flying airplane over all, but the Camel is really enjoyable and I would absolutely go dogfight with it without concern for spinning out of the sky.

[BMA_Hellbender]

1 hour ago, Chill31 said:

I just finished a couple of flights in the Camel, and it is really a sweet flying plane.  The idea that thin wings stall aggressively and cause wild spinning is just not true.  I really tossed it around (video still needs editing), and it handled it all so well! The Dr.I is a nicer flying airplane over all, but the Camel is really enjoyable and I would absolutely go dogfight with it without concern for spinning out of the sky.

How many times do we have to tell you to fly these planes on higher realism settings.

[ST_Catchov]

She's a beautiful lady. Thin wings rule man. I'm insanely jealous and wanna get into her cockpit. Looking forward to the sexy vid !

 

How's the Se5a going Chill ?

[Chill31]

8 hours ago, ST_Catchov said:

How's the Se5a going Chill ?

The SE5a is a lady in waiting for the Dr.I right now.  I'm trying to do some detail work so that the Dr.I is as close to original cockpit as I can get it for the upcoming Fokker Scourge.

 

The videos came out better than I expected!  You will enjoy these!

 

After first review, the Camel takes 6 seconds to do a barrel roll, just like the Dr.I...BUT it takes 3 times the stick force to do it.  You really have to man handle the ailerons!  Considering it has the same aileron attachment and style as the Nieport 28, I am not surprised, since Mikael Carlson also says the N28 ailerons are HEAVY at high speeds (high speeds being 90+ mph).

[No.23_Starling]

2 hours ago, Chill31 said:

The SE5a is a lady in waiting for the Dr.I right now.  I'm trying to do some detail work so that the Dr.I is as close to original cockpit as I can get it for the upcoming Fokker Scourge.

 

The videos came out better than I expected!  You will enjoy these!

 

After first review, the Camel takes 6 seconds to do a barrel roll, just like the Dr.I...BUT it takes 3 times the stick force to do it.  You really have to man handle the ailerons!  Considering it has the same aileron attachment and style as the Nieport 28, I am not surprised, since Mikael Carlson also says the N28 ailerons are HEAVY at high speeds (high speeds being 90+ mph).

This is all so fantastic - thank you! Are you formally recording any of this data anywhere? Also, are you teasing us with hint of actually flying the SE5 or do you have something in the works?

[Trooper117]

16 hours ago, Chill31 said:

but the Camel is really enjoyable and I would absolutely go dogfight with it without concern for spinning out of the sky.

 

Yes, that's all well and good, but has it's wings fallen off yet?

[=IRFC=Tunes]

Awesome stuff Chill. Can’t wait for video! Congrats again on that EAA article.