Heinkel He-162 "Spatz", 1944

[aleatorylamp]

Perhaps not so bad after all

Hi Ivan,

OK, no problem - we´ll stick to MPH. I´ll do any subsequent speed test reports in MPH!
The Pilot´s report uses MPH anyway, and Wikipedia and other sources quote both MPH and KPH.

More important will be the workaround for the low performance at altitude.

So just for the record, results in MPH for the last speed test I did after correcting the excess S.L. performance:

S.L. performance compared to specs in Wikipedia:
At _92% throttle: _9500 RPM, 1760-1781 flb and 491 mph (correct)
At 100% throttle: 10100 RPM, 1968-1991 flb and 515 mph (38 mph under) aim: 553 mph

Your max. speed of 560 mph at 500 ft sounds quite OK!

6000 ft:
At _90% throttle: _9500 RPM, 1515 flb and 495 mph
At 100% throttle: 10200 RPM, 1713 flb and 518 mph

20000 ft: performance compared to specs in Wikipedia:
At _83% throttle: _9500 RPM, _971 flb and 500 mph (22 mph under) aim: 522 mph
At 100% throttle: 10350 RPM, 1150 flb and 533 mph (29 mph under) aim: 562 mph

The comparisons I made in the previous post included a confusion in the altitude. I had taken the 6000 meters to be 6000 ft, and was wondering where I´d got the 20000 ft reference from.... Merry-go-rounds again.

Anyway, my present results are only a bit slow at altitude, and not so excessively fast at S.L. anymore - except for the Boost Burst which is a bit low at S.L.

Cheers,
Aleatorylamp

 

[hubbabubba]

Hello Aleatorylamp,


I will have to disagree with Hubbabubba on this one. I think the AIR file needs some serious adjustment for drag.
While the existing AIR file is flyable, its flight characteristics can be considered a mod because it hardly bleeds off speed even with hard turns (retains energy too well) and has a glide ratio comparable to a sailplane or perhaps even better. With Engine off, I did not lose speed as one would expect with a fighter with a small wing. I ran out of patience before I got any meaningful data here. (I tested out your TF-104 this morning and found that one was NOT flyable)
As I mentioned before, with the engine at idle, it does not lose speed at all which makes even a simple power-on stall test impossible.


Also, was it intentional to have the guns connected to the cannon trigger?


On a related note: Pretty soon I will need to work on a Jet or Rocket AIR file for a project that has been sitting in my workshop for ages. I started with the Learjet AIR file but never managed to get it to work well.


- Ivan.

I know that old habits die hard, Ivan, but I failed to see where we really disagree here. My comments about drag were only concerned with slowing down enough to make a landing without going poof! As I said, I just went easy on the flight portion, bar the inverted portion, to see if it was flyable. Could it take-off? Could it climb? Could it turn? Could it fly level? Could it land? I could answer yes to all but the last question. Note that for that first contact, I was simply using stick and pedals of my CH triumvirate as the throttle was tucked behind the screen. I am suffering from a serious lack of space. To use the CH throttle, I have to forage in all the stock piled behind my three machines, fold-down the laptop to my right and put the bulky throttle on top of it.


So after a short while, I turned to port while reducing throttle to 50% with the keyboard and, seeing I was still going very fast, put one increment flaps while still turning. As I was about at 2 miles from the runway, I lowered the gears and speed quickly went down, and so did the a/c! So I pushed the throttle to 100% (still keyboard) and, cutting the daisies, barely made it to the service area in front of the runway, bounced a bit and made a big whole 50 yards passed the treshold.


Hence my interrogation about perceived disagreement. I too think the AIR file needs some taming. I have done some more flying with the little critter since then and, in its clean aspect, the a/c is way too fast, but all that changes once at low speed with flaps and gears extended. All my following, and successful, landings were done on full flaps, gear down and throttle (this time with CH) at full almost up to the flaring zone.


Some reports state that critical Mach number was an unimpressive 0.75, mostly due to the engine position and the the bulges at wings/fuselage necessary for the gluing technique.


I will decipher the German site I found and try to land according to their instructions, only then will I have an idea of the balance between clean and dirty drag necessary.

 

[aleatorylamp]

Hello Hubbabubba,

I think you will find the .air file in my post #39 somewhat better. The correct speed test report for that .air file is in my post #41.
In post #39, I messed up on the 6000 ft aimed-for speeds that were not reached - they should really only have referred to 20000 ft (6000 metres approx).

Maybe I can tweak the .air file a bit better. I need some advice here, also from Ivan if possible:
Maybe now there is excessive Drag on flaps and Landing Gear?
Anyway, meanwhile, at least the new .air file is a bit more enjoyable than the old one!

Thanks again for all your testing and your feedback. Now I´m looking into the Radio Navigation Display System you mentioned, to see if I can perhaps use the Me109 or Fw190 ADF instead.

Cheers,
Aleatorylamp

 

[Ivan]

Hello Hubbabubba,

Perhaps I should have stated it better. I was really objecting to the conclusion reached by Aleatorylamp from your test that there were no changes needed on the AIR file. You had not made that statement.
I am not sure how I can really help here since I don't know how to tune the jet engine for different altitude performance.
I looked through the jet engine tuning document that Aleatorylamp translated but did not find quite what I needed.
I suspect that the FS98 Jet engine may lack altitude tuning in a manner similar to the FS98 Piston engine.


Hello Aleatorylamp,

I actually did quite a bit of tuning on my copy of the Spatz AIR file.
The values I settled on were 0,020 for Drag (according to FDE which is just a touch lower than that for the P-40M I was working on. The value for flaps would normally 0.017 but with the very small wing, I pushed the number up to around 0.035 to 0.040. Landing Gear should be pretty comparable but I did not tune that yet.
The biggest issue as I mentioned earlier was the lack of ability to increase engine power at altitude.
6000 meters is around 19680 feet which is why I was testing at 19700 feet.

One of the other issues is that the longitudinal trim needs a massive adjustment. It is probably inherited from the Learjet which has a pretty similar problem.

- Ivan.

 

[Ivan]

Engines

Hello Aleatorylamp,

Here is a project I built as a simple visual model at least 10 years ago.
I think the visual model looks good, but the engine in this AIR file simply does not make sense.
This missile (literally) carries just over 400 gallons of fuel and burns it in well under 5 minutes.
Thrust is 1429 pounds and remains constant at full throttle.
The handling is about where I want it and it moves well while under power.
The big problem is that although I can tune the engine for more power and even more run time, I can not do this realistically or in a manner that I can use in a real project, so it sits incomplete.

Perhaps it should have a jet engine instead of a rocket.......
Now all I need to do now is to find a guide to tuning jet engines that I can actually understand.

- Ivan.

 

[hubbabubba]

Just saw your Okha, Ivan, or about a third of it. Is it only me?

 

[Allen]

Me too.

PLACEHOLDER TEXT

 

[aleatorylamp]

Hello all,

Yes, I was wrong about my comment on the Drag being OK - I´ve explained that I only meant it in relation to landings, and only noticed the faulty excessive speed after Ivan had stated it.

The new .air file is much better, if anyone wants to try it out. I increased FDE zero lift Drag to 0.02197 and this is more successful.

Ivan, as you say, jet-engine tuning is more limited than prop-engine tuning. I´ve been trying to sort things out on the "Spatz" (Sparrow) - that´s what Heinkel called it, it was Hitler who called it "Volksjäger", and then, the production project was called "Salamander".

It definitely seems true that only restricted control over engine performance is allowed. After fighting it out with the different parameters, I realize that there are a number of ambiguities and incomplete or even erroneous comments in the "guide" I translated - not in the translation, but in the content of the "guide" itself.

A useful one refers to balancing out idle- and max. power RPM, but any modifications in Idle speed will require adjustments to Max. RPM.Then, Oil and EGT temperatures and oil-pressure readings can also be adjusted to fit different engine manufacturer specs, but these often do not behave logically, and will understandably affect RPM.

For the moment I don´t know enough yet to produce a guide of my own, and I haven´t found a different one.

Yes, it appears that the Okha pic is invisible for the lower 2/3, and, as you said say, a jet-engine .air file will probably be better than a rocket one. The Me-163 Rocket plane (3800 flb) I mentioned is by a Captain Slug (CS), and has a jet-engine .air file! If you are interested I can send you the Komet plane.

I also have the FS98 Opel Sander Rocket - also with a jet-engine .air file! It had sixteen 55 flb solid fuel Sander rockets. Fritz von Opel flew it himself at the risk of his life, but escaped unscathed.

Cheers,
Aleatorylamp

 

[Ivan]

Hello All,

I am not quite sure what happened on that screenshot. I actually tried about two more times when I noticed the partial image.
The others were even worse. The really strange thing is that the image pulls up fine on the Windows 2000 machine it was generated on.

Here is a better image. Most of you have seen this one before but it seemed relevant in terms of AIR files.
The maximum level speed I have gotten out of this beast is about 585 MPH or just a touch more.
It runs out of fuel before it really stops accelerating.

Here is a screenshot of yet another project I did for the old JG 57 folks.
The model is not mine; Just the nose and a bit of clean up were my work.
It doesn't handle too badly but definitely could use some tuning.

- Ivan.

 

[aleatorylamp]

Hello Ivan,

The Okha screenshot shows a nice, clean build. One would be inclined to feel that it deserves to see the light of day with an upload!

I looked into the some flyable .air files by a certain Christoph Ruhtenberg, who was writing FD for FS98 until 2007.

For a Me163 Komet rocket plane model (by Captain Slug), he wrote some good jet-engine FD that had 3800 flb thrust, 400 USG fuel, and 4000 lb in Dry Weight (zero in DP). It gave a very fast and maneuverable little machine! Incidentally, Zero Lift Drag is also very low here!

He also provided a souped-up version with 4484 flb power, as well as an easier-to-fly, tuned-down version with 1764 flb, which is the one that I was trying to adapt for an initial trial for your Okha.

Looking into the Okha specs, power looked similar: 1761 flb thrust (3x587 flb rockets), although you state 1429 flb, so I´m not sure if it is Model 11. However, the Okha´s wings are about half the size of the Komet´s, but the worst is the weights: Loaded weight for the Okha is quoted at 4718 lb, and this just won´t add up. The plane is too heavy for the power and will not fly:

Pilot: ____________200 lb
Empty weight: _____970 lb
Ammonal Warhead: 2646 lb
400 USG fuel: ____ 2640 lb
-----------------------------------
Total:___________6456 lb

Incidentally, range for the rockets was only 23 miles, but if one includes the gliding slope after being dropped from the Betty Bomber, prior to the 8-10 seconds of rocket-powered flight that accellerated the machine to 650 mph just before the target, range was 55 miles. Data I found talked about 3 solid fuel rockets, and you mentioned 400 USG fuel, so that seems contradictory too, and I´m a bit lost.

Anyway, this project could perhaps be well worth while looking into, if you like.

Cheers,
Aleatorylamp

 

[hubbabubba]

Hey guys!

I don't know if it's of any interest for you, but CFS1 does have one native included rocket AIR file; the V1.

 

[aleatorylamp]

Hello Hubbabubba:

I tried using the V1 .air file to test it for a rocket plane, to see how it works, but it didn´t show up in the aircraft index.
But if you mention it, then it should work! Now I remember that the Aircraft type has to be changed from 2 (AI drone) to 0 (flyable AC).
The funny thing is that it only has 2 parameters: foot-pounds Thrust and Impulse, the latter being the accelleration, possibly?

Thanks! I´ll investigate, just to see what this type of .air file does, and can do.

Ivan was complaining about the very reduced possibilities offered by the rocket .air file, but I´m curious as to what there is.

I just made the V1 visible and it took ages to take off, but once in the air the vile thing looks quite scary. Here´s a screenshot, also from the Me-163 Komet ...and one of the Opel-Sander Rocket plane I mentioned - it could do all of 95 mph!!

I don´t like the FS98 smoke plumes though - and this brings me to a point: The Komet has a nifty little white fire triangle coming out the back - maybe I should implement a yellow-orange flame for the Sparrow, depending on how far the throttle is opened? I saw a photo of one with a huge blown-torch type fire raging out the turbojet nozzle!

Update:
Experiment Findings:
A) Of the 2 sole Engine parameters, The second one called "Impulse" looks like a scale-multiplier to multiply the Thrust entered in the first parameter, and would cater for the number of rockets pods employed. The Okha could then have a "3" here, and the Thrust parameter would be 587 flb. ...more realistic than just having the total of 1761 flb and an Impulse of 1.
The Opel Sander Rocket plane would then have 55 flb Thrust and 16 Impulse for the 16 rockets.
As regards fuel, the parameter seems straight forward with USG. The V1 has 491 USG of fuel in the AI .air file... so for solid fuel, the USG would just account for the weight, I suppose.
B) Important: I can´t get the sound to work, but the panel seems to be OK, and also the Beckwith Gauge Stack.
C) There doesn´t seem to be a parameter to regulate fuel consumption, and I haven´t tested for range yet - This was one of Ivan´s problems with the Okha.

Interesting experiment, by all means! Comments are of course welcome!
I had always wondered how to be able to use a rocket .air file, and where to get it from, as the V1 had been invisible all this time!!

Cheers,
Aleatorylamp

 

[Ivan]

Realistic? No.

Hello Aleatorylamp, Hubbabubba,

My intent with the Ohka was NOT to have a realistic simulation.
I built the model because I liked the look and didn't have the intention of doing a release at all.
There are quite a few times that I build a model just to see the appearance in the simulator.
Womble55 built a glider a while back and I thought a technique would work well for that model, so I built one also.
That glider will probably never get finished.

The AIR file I am using for my version of the Ohka is completely unrealistic.
(The project doesn't even have any sound configured yet.)
It was intended as just a first step to testing out how Jet / Rocket engines worked.
I wanted a nice handling package that had enough flight time to try a few maneuvers.
Up until yesterday, I had no idea what the actual thrust value was because I was just playing around and exact numbers did not matter.

At this point, my goal if I were working on a Jet / Rocket would be to figure out how to tune thrust and how to adjust the thrust change with altitude and to understand the meaning of the other engine parameters. The handling factors should hopefully be similar to Piston engine aeroplanes.

- Ivan.

- Ivan.

 

[hubbabubba]

I tried using the V1 .air file to test it for a rocket plane, to see how it works, but it didn´t show up in the aircraft index.
But if you mention it, then it should work! Now I remember that the Aircraft type has to be changed from 2 (AI drone) to 0 (flyable AC).
The funny thing is that it only has 2 parameters: foot-pounds Thrust and Impulse, the latter being the accelleration, possibly?

Yep! From 2 to 0 at section 105 in AirED. The AIR file is a "slug", but the entries can be tweaked. smilo will remember the epic "V1 raids" we organized for the guys at AAC Sunday shing-ding. I had modified the file to obtain something flyable. We would launch from catapults that, upon picking-up speed, would elevate the V1 to a few thousand feet, from which point we would adjust heading and altitude, engage the auto-pilot, and let them go their ways towards London. We had 5 launching sites and smilo was taking care of much of the launches with his personal network of PC and watch on his giant TV screen as if he was in NORAD, I wish I could have been there!

You can also change entries like #310 (Engine Type) from 4 (Rocket) to 1 (jet). Adding/removing entries is also possible.

 

[hubbabubba]

Experiment Findings:
A) Of the 2 sole Engine parameters, The second one called "Impulse" looks like a scale-multiplier to multiply the Thrust entered in the first parameter, and would cater for the number of rockets pods employed. The Okha could then have a "3" here, and the Thrust parameter would be 587 flb. ...more realistic than just having the total of 1761 flb and an Impulse of 1.
The Opel Sander Rocket plane would then have 55 flb Thrust and 16 Impulse for the 16 rockets.
As regards fuel, the parameter seems straight forward with USG. The V1 has 491 USG of fuel in the AI .air file... so for solid fuel, the USG would just account for the weight, I suppose.
B) Important: I can´t get the sound to work, but the panel seems to be OK, and also the Beckwith Gauge Stack.
C) There doesn´t seem to be a parameter to regulate fuel consumption, and I haven´t tested for range yet - This was one of Ivan´s problems with the Okha.

You must be using FDE. In AirED, at section #450, I have "Specific Thrust Constant (lb-sec/gal) (Info: Thrust(lb)=STC*gal/sec) and "Fuel Flow Rate (gal/sec) (Info: Thrust Time=Capacity in gallons / Flow Rate).

FDE was not revised as often as AirED. The infos were added by individuals making discoveries while tinkering. I did some on my own infos. Can't remember those I made and those already there.

In my "flyable V1", the section #450 was removed and replaced by #600 of the "old" FS09 AIR files.

 

[smilo]

aaah yes, those thrilling days of yesteryear.
that scenario was one of our better efforts.
so good, it went on for a couple/three weeks.
you built 'em, i flew 'em and the boys tried to destroy 'em.
as soon as one went down, i'd launch another.
then, they had to search and destroy the sites
while the axis pilots tried to defend them...fun stuff.

 

[aleatorylamp]

Combined: 520 Rocket Engine + Section 600 Engine FS98 Jet !!

Hello all!

Fascinating what you guys were doing with the V1 ramps and all that! - what fun!

Hubbabubba, that was a great comment on the .air file sections that can be combined. Thanks very much indeed!

For the Rocket experiment I´m using AirEd, but one of the later versions hangs on my computer, so I was using the .ini file from 2000.
The .ini file from 2007 calls the two sole engine parameters the way you say: Specific Thust Constant and Fuel Flow (gal/sec).

So, why does it multiply the flb thrust shown in the Beckwith Gauge by the integer entered in Fuel Flow (aka "Impulse") - this seems not to tie in logically... 1 Gallon per hour gives me 1761 flb, and 2 USG gives me 3521 flb, 3 USG gives me 5282 flb.
I think the old .ini file calls it something more logical - anyway, it seems to be a thrust scalar, and will obviously increase fuel consumption proportionally, so fuel will have to be regulated from within an added Section #600.
Incidentally, does Section #450 Delta C (Beta)M necessarily HAVE TO be removed if Section #600 is added?

BIG QUESTION:
Does anyone know the weight of solid fuel burn-off? The normal jet engine is 400, and for an old Turbojet, it´s 440.
So.... with 3 solid fuel rockets giving 1761 (or 1492 flb), how far should the solid fuel equivalent of 400 USG allow the OKHA to travel at constant full power?

So, from your comment, it is possible to add the Jet section 600 (and perhaps a few others below if of interest: 601 power curve, 602 Unknown, 603 EPR (engine pressure ratio), but perhaps not parameter 604 N1 because rockets do not have a N1 spool.

One thing I noticed, is that the two parameters in 520 Rocket Engine override the thrust entries in the added 600 Jet engine section.

From this I can deduce that fuel flow and fuel consumption - hence range, CAN be controlled for the Rocket engine.

Ivan: Even if you don´t want to upload your OKHA (what a pity...it looks great, I think), this does seems like the solution for your range problem. So, 400 USG fuel is not a true figure. 8-10 minutes´ solid fuel for the three 587 flb rocket motors would weigh far less, I´m sure. If one were to calculate the time/range for 400 USG, and translate this into solid fuel, fuel density would need to be reduced from 6.6 (kerosene) to something much lighter.

Cheers,
Aleatorylamp

 

[hubbabubba]

M$ and logic... interesting concept.

When their team build the AIR files for flyable and non-flyable a/c, they certainly had some "master file" and a house program to brew-up quickly all necessary AIR files, but they never did released them to grand public. We can say the same for many other things, MDL, DP, sound files... I can go on and on and on...

There was talk of a Me 262 being in the menagerie, upon release or in a "patch", but it never was. For the most part, CFS1 enthusiasts "fun" was derived of a masochistic pleasure of deciphering those files and what they meant.

 

[aleatorylamp]

A new thing deciphered, perhaps?

Hello Hubbabubba, hello Ivan, hello all!

Looks like the deciphering has been (and still seems to be) one of the rare pleasures of the old sim .air files!

Section #520 Rocket Engine overrides Section #600 Engine FS98 Jet if both are present, although it won´t hang.
So, you can only have EITHER one OR the other. Too bad? Not really, it gets great toward the end of this post!

First, the jet .air file:
You can control endurance/range with section #600 by manipulating Fuel parameters:

1) Fuel Density: 6.6016 lb/gal for jet-A1 kerosene
2) Consumption/TSFC: 400 for normal jets, 440 for old turbojets.

Reducing fuel density, consumption will rise.
Inversely, increasing density will reduce consumption.

I tested the effects using a 3800 flb thrust engine.

At the default consumption setting of 400, consumption changed with different densities of fuel:
6.6016 lb/gal kerosene: 7.0 Gal/min
6.0000 lb/gal gasoline: 7.7 Gal/min
8.3400 lb/gal rocket a: 5.4 Gal/min of peroxide/methanol etc.
1.0000 lb/gal rocket b: 44.8 Gal/min of exaggerated fictitious rocket fuel.
2.0000 lb/gal rocket c: 16.8 gal/min of fictitious rocket fuel.

Then, you can also alter the Fuel consumption parameter:

Tests using Using 8.34 lb/gal rocket fuel:
100: 0.1 gal/min
200: 0.3 gal/min
300: 1.1 gal/min
400: 5.4 gal/min
500: 8.4 gal/min (this seems to be the maximum, increasing further does not increase consumption.

A liquid-fuel rocket-plane like the Me163 Komet, uses rocket fuel: Simplified, it´s a methanol-hydrogen peroxide combination with a potassium cupro cyanide catalyst. Uugghhh!!! Density is like that of water, so it´s 8.34 lb/gal, and fuel tanks hold 450 USG in total. Range is 25 miles at 600 mph, so endurance is 24 minutes. Thus, consumption would be 18.75 USG per minute.

Testing could be done with a 1/10 tankage of 45 USG, looking for an endurance of 2.4 minutes.

But, MUCH EASIER !!:
The #520 Rocket Engine Section CAN ALSO BE USED to control endurance, not only power. It is a combination of both, and not immediately apparent: Multiplying the two parameters you must arrive at the total flb thrust!!

Watch:

Test 1:
Normal Thrust entry and fuel flow 1.
Specific Thrust Constant (lb-sec/gal): 3800 flb thrust
Fuel Flow Rate(gal/sec): 1.0
The 45 USG in the tank are used up in 45 seconds: 45 gal/min

Test 2:
Doubling thrust and halving fuel flow:
Specific Thrust Constant (lb-sec/gal): 7600 flb thrust
Fuel Flow Rate(gal/sec): 0.5
The 45 USG in the tank are used up in 1.5 minutes: 30 gal/min

Test 3: BINGO!! BANG ON!!
increasing thrust again and reducing fuel flow further (a mathematical division could also be in order...)
Specific Thrust Constant (lb-sec/gal): 12160 flb thrust
Fuel Flow Rate(gal/sec): 0.3125
The 45 USG in the tank are used up in 2.4 minutes (2 min 24 sec): exactly what I needed for the Komet: 18.75 gal/min

Very easy, very practical to regulate endurance! So, Ivan, now your can try and adjust the range for the OKHA, the ephemeral Cherry Blossom!

Enjoy!
Cheers,
Aleatorylamp

 

[hubbabubba]

And here you go, Aleatorylamp, it is confirmed! Your're a masochist!