Heinkel He-162 "Spatz", 1944

[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]

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]

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]

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!

[Ivan]

Hello Aleatorylamp, Hubbabubba,

I think I may have lied to you.
The actual fuel load in my Ohka is around 800 gallons which I believe gives only around 4 minutes flight time.
I seem to have misplaced my stopwatch but have one on order from China.

The reason I had thought it was around 400 gallons is because that is all that remains after a quick takeoff.

The engine start seems to do nothing unlike the same thing for a Jet engine.
Since I have no sound configured, I can't be absolutely sure, but I can see that the Thrust remains at Zero until the throttle is advanced.

I did not have the same results as Aleatorylamp did in changing fuel weights.
I dropped the fuel weight per gallon down to 0.25 and found that it did not seem to affect the thrust reading at all though acceleration was greatly increased of course.

I also greatly increased the thrust (doubled it) and found that with the lighter weight and greater power, controllability was VERY poor.
Perhaps I need to stiffen up the controls at high speed.
At the moment, I am finding that I am hitting the overspeed warning pretty quickly. I believe it is set for Mach 1.

As a side note, the thought had occurred to me that perhaps I should build a more worthy Rocket plane and if I have to do that, the Northrop HL-10 has always appealed to me. While looking for videos, I eventually ended up watching the entire
Six Million Dollar Man TV Movie from 1973. I had always enjoyed the Old TV show, but had not seen the movie before.
My version of the HL-10 (if I should ever build it) will have a much greater range and not require an airborne launch.

- Ivan.

[aleatorylamp]

Hello Hubbabubba, hello Ivan,

Ha ha! Anyway, interesting!

I still have to see if the override of section #600 by section #520 is because I didn´t scrub section #450. I missed out on that.

Different results:
I was testing for endurance - consequently range and fuel consumption, so they were conditioned by the 3800 flb Test-Engine itself, and the 8.43 lb/gal peroxide/methanol/cyanide rocket-fuel density. Density, together with fuel consumption, can be used in the jet engine .air file to get range right.

It is very interesting to see that fuel density affects accelleration and control! I hadn´t noticed that, as I wasn´t testing for it.

What I thought was very effective, was the proportion between the magnitude of the two Rocket Engine parameters in section #520, which multiplied, should always give the correct flb engine thrust, but whose proportions define fuel consumption, making for a very easy way of regulating range. Doing it this way, avoids the accelleration and control side-effects of fuel weight manipulation.

I suppose one of the deterrants for an Ohka upload (I´d always misspelled that), is the sinister concept of a plane specifically designed to kill its pilot - although wartime mass-bombing of cities is also argueablty sinister. Thus, the Northrop HL-10 is of course much more appealing!

Anyway, the info update on the 800 USG fuel for the Ohka now makes it even heavier, but no matter, it was just a question of trying to find a solution for the range issue within a rocket .air file - nothing to do with Ohka flight characteristics as such.

Anyway, as regards the Heinkel He-162 1944 turbojet, the FD at the moment are those I had attached to post #39. From what I can see, it is much better than before, but could do with some more testing before uploading an update - I definitely want to avoid having to upload an update on the update!

Cheers,
Aleatorylamp

[aleatorylamp]

Hello Hubbabubba, Hello Ivan,

I´ve been trying to balance out the Sparrow´s speed at altitude. I have got it a little better, at the price of a small speed increase at S.L., which however I think is quite acceptable:

The .air file in post #39, despite having a correct S.L. max. normal speed, fell short at altitude by 22-29 mph, and by 38 mph with S.L. Boost speed.

Now, after some Zero Lift Drag and Induced Drag adjustments, although the normal S.L. max. speed is now 18 mph over, speeds at altitude are now only 11-13 mph under, and S.L. Boost speed is only 23 mph under.

I have found no provision in the FD for any possibility of compensating loss of speed at altitude - there is nothing equivalent to propeller advance ratios in the FS98 jet .air file. There isn´t even a graph which would adjust speeds with respect to altitude.
The only power or thrust graphs there are, relate to Mach, so that´s no use.

Work on the model itself has resulted in fewer bleeds, and the new Sparrow just about ready for an update-upload, which I will probably do in a few days. The panel is also much better and more true-to-life.

Thanks very much for your help in pointing out all the shortcomings, because the model has definitely benefited from the resulting improvements!

Cheers,
Aleatorylamp

[hubbabubba]

Hello Aleatorylamp,

Just installed the new AIR file and did a very short test.
-Taxiing is still next to impossible. I then realized that, in flight, you have almost no yaw control. The rudders can't do much. As the a/c had a reputation of side slipping, this is quite irregular. I tried to go into voluntary side-slips but could barely move the nose by 2-3° top.

-Drag, clean an dirty, seems to be getting there, but I will let Ivan do his own appreciation in the matter as he has done more testing on the subject.

I'm still deciphering the German "Pilot Handbook" and I've found that the Spatz could do RATO with two solid rockets attached under the wings and jettisonable after 6 seconds. They had to be lit-up when the a/c had reached 100-150 kph (62-93 mph). Normal t/o roll was 650 m (2133 ft) on concrete and 10% more on grass/sod. T/o speed was 190 kph (118 mph) but could be attempted at 180 kph (112 mph). Gear had to be retracted before reaching 350 kph (217 mph). Flaps for normal t/o were at 20°, which was reached by pomping the left red handle marked Landenklappen about 7 times. From the cockpit, you should barely see the trailing edges of your flaps under the wings. Alternately, ground crew could see a white line traced on the side of the wing trailing edge interior. Flaps were maintained in position by turning the handle clockwise.

The flaps comments lead me to believe that it was a pneumatic, not hydraulic, system, at least for the pumping part. Liquid simply can't be compressed.

Other interesting numbers;

Speed limits:
-700 kph at 5000 m (436 mph at 16404 ft)
-600 kph between 5000-7000 m (373 mph between 16404-22966 ft)
-500 kph between 7000-9000 m (311 mph between 22966-29527 ft)
-400 kph between 9000-11000 m (249 mph between 29527-36089 ft)

Landings were performed as 3 points or 2 points touchdown. Nose wheel first would break it. Gears could be lowered under 350 kph (217 mph). Flaps could be lowered to 20° t/o position between 300 and 250 kph (186 and 155 kph) and then fully under that speed. Landing speed was around 200 kph (124 mph) and should not go under 190 kph (118 mph) and the a/c should roll as long as possible on the main rear wing.

I will try to go by the number and see what it does.

[aleatorylamp]

Hello Hubbabubba,
That is some very interesting additional information! Thanks very much.
I had only seen the pilot´s handbook for 30 dollars or so. Drool... Very handy for further FD adjustments. I won´t upload anything before back-checking with Ivan and yourself.

The speed limits you mention for the different heights would perhaps be under maximum continuous?

I can decrease Flap-deployment time. Interesting mechanism you describe!
I haven´t adjusted anything on the flaps as yet. The only effect on them in the present .air file is the overall increase in Zero Lift Drag, which affects them too.

Sorry about the bad taxiing! I know it was mentioned a few days ago, and I looked into Steerable yes/no, and found it ON, but failed to check the rudder moment. Sorry, will fix!!

So then, we could also have an additional RATO version for the Sparrow once the rest of the FD is sorted out. Fascinating! There are more than enough parts left over. Let´s see if there are no bleeds.

I´ll study the info you sent, and see how I can adjust speeds.
Fine teamwork, thanks!

Update:
Yes, there seems to be a serious rudder problem. Rusty and seized hinges!... Although autocoordination is off and a control-surfaces gauge records rudder movement, and although the rudder moment should be OK at 178 (I increased it to 195), it still has no effect! There are quite a few parameters to do with Yaw, so it´s a bit more complicated. I´ll see what´s going on.

Update 2:
Rudder and elevator control is terrible! I have used data from other planes that work, and it seems better now. The cross-effects that rudder has on roll makes it more difficult and although rudders now make the plane yaw, they end up rolllng it quite strongly even though rudder effect on roll is at zero.
Then, turning during taxiing now works, but it is very still very spongy.
What is absolutely clear, is that I am terrible at adjusting the flying characteristics of planes. Not my cup of tea by any means!!
Anyway, as soon as get the speeds better, I can post another updated .air file.

Update 3:
From your last comments, contrary to what I had feared, speeds at altitude are not too slow! In effect, they are wAy too high. I am getting 500 mph+ above 20000 ft instead of what you just posted.
My references, Wikipedia, Aviation History Online Museum and others seem not only to be insufficient, but totally erroneous!
The first ones all coincided, stating a maximum speed of 562 mph at 20000 ft, and 553 mph at S.L. (presumably Boost-burst).
Then, I found two more stating 490 mph for S.L. and 522 mph for 20000 ft, which led me to believe these last speeds were for maximum-continuous.

So, question: Does your hand-book state a S.L. speed limit? I assume this would be at maximum-continuous, for the time being - i.e. at 9500 RPM.

Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp, Hubbabubba,

The reason for speed differences is probably because in the Pilot's Handbook, speeds are stated in Indicated Air Speed.
The Wikipedia article appears to be pretty reliable for data. The 562 MPH at 19680 feet and 553 MPH at Sea Level are what I would go for.
Regarding poor handling, I can take a look at it in the next couple of days. Been very busy with a couple other projects (not flight simulator stuff) and also trying to figure out some discrepancies between the several installations of CFS that I have.

I am pretty sure I have an entry in Eric Brown's book on this aeroplane, but where can the pilot's handbook be found online?


Last night, I checked out the V1 Cruise Missile.
My reference data here is mostly from Wikipedia and other Web searches. I have never really been terribly interested in the missile.

From Test Data on my CFS Development machine in comparison with Actual Data:
Fuel: 491.0 Gallons at 6.0 Pounds per Gallon.
Actual Fuel Capacity is around 150 Gallons of Gasoline (varies from 130 to 150 depending on source).

Zero Fuel Weight: 1850 Pounds.

Loaded Weight of Actual V-1: around 4750 Pounds which makes the Unfueled Weight 3850 Pounds.
One source puts the unfueled weight at 3855 Pounds which is consistent.
Loaded Weight of CFS Version: 4796 Pounds - Pretty close.

The Argus Pulse Jet was capable of 660 pounds thrust but may have varied a bit. (They tended to run faster at the end of the mission.)
The CFS engine gives 769 pounds thrust which is a bit high but not too unreasonable.

Speed of the V-1 was reported to be 390 MPH to about 435 MPH.
The speed of the CFS version is limited to about 430 MPH with a ground take-off because it runs out of fuel before maximum speed is reached.
With in-flight refueling, it reaches a maximum of 444 MPH at 1500 feet altitude which is a bit below its actual operational altitude.

So.... From my viewpoint, the CFS V-1 Flying Bomb other than its very short flying range is not a bad representation of the actual weapon.
One very disappointing aspect is that it has no sound files configured so other than an engine whine from inside, it is completely silent.

- Ivan.

[aleatorylamp]

Hello Ivan,
Thanks for your confidence-boosting confirmation about going for the 562 and 553 mph for altitude and S.L. respectively, and for your clarification about the probability of the handbook speeds that Hubbabubba supplied for the Sparrow as being quoted in IAS. Now they will help to achieve finer adjustments!

Interesting too, are your findings and deductions on the V1.
I had the feeling it was quite good too, except for the fact that a take-off run is very slow for the lack of a powered catapult. Incidentally, I wonder if it is easy enough to use the CFS1 Scenery Editor to place some launching ramps for somewhere to practise.

Anyway, the 660 flb V1 power is entered as 770 flb in the .air file:
The two entries in #520 Rocket, which default at 350 and 2.2 (350x2.2=770), could be changed to 700 and 1.1.
Thus, endurance can be duplicated while power is kept the same!

OK then! Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

I would not pay too much attention to the speed limitations that are in the Pilot's Handbook.
They are probably Structural / Mach / Controllability limits.
None of those can REALLY be duplicated in CFS to the degree of precision that is described there.
(If you know that it is possible, please describe....)

It IS possible sometimes to set up a vibration or oscillation at a certain speed as I did to limit the A6M's never-exceed speeds, but it is definitely not something that can be done reliably.
You can mimic some of the Mach effects of course as I tried to do with the P-38s but that is on the assumption that there really is a controllability problem at high speeds.

Yes, we are digressing a bit but I thought I would mention my poking around with the Northrop HL-10.
Drawings are NOT easy to find and some of the data is contradictory even in something so simple as dimensions.
Willingly or not, I am certainly learning more about the concept and history of this rocket plane.
The entire fuel load of the HL-10 can be expended in 100 seconds of a full power run.
Since the idea of flying a glider really does not appeal to me, I would probably set it for much more than that for a CFS model.
Without drawings, it is pretty hard to build via photographs.

- Ivan.

- Ivan.

[aleatorylamp]

Hello Ivan,

Great! All the better, then I won´t complicate matters any further. Now I have to balance out the speed differences.
Probably the option to settle for slower speeds at altitude in order to be correct at S.L. (non-boost) is not the best one.
I think I´ll go for more accuracy in altitude speed and S.L. Boost speed, at the expense of some increment in non-boost S.L. speed, because this would achieve a greater number of correct points along the power curve.

Re. Northrop HL-10:
I don´t mind digressions at all - after all we are illustrating different points about non-propeller a/c, and trying out different adjustments on FS98 jet .air files and CFS1 Rocket ones, so it´s all quite on-topic.
I saw quite a few HL-10 drawings on the net but didn´t check enough to see if they were reliable enough for building.

Then, I tried out something on the CFS1 V1 Rocket:
This, incidentally, appears to have had a range of 150 miles, so with the correct 150 USG tankage you mentioned, gives a fuel consumption of 1 Gallon per mile, which at 400 mph gives 0.016 gal/sec.

Section #520 Rocket Engine entries:
By entering 41250.0 and 0.016 into the two parameters, it will give exactly 659 flb thrust in the Beckwith Gauge, and the correct fuel consumption. Accelleration also seems OK. At the moment I´m checking the speed.

Incidentally, I saw a variant planned on the V1: The Reichenbach, a manned version of the V1, a German Ohka! This had a crude cabin just infront of and below the pulse-jet air-intake. It entailed the pilot flying to the target with crude controls and instruments, aiming the bomb at the target in a dive, and then trying to open the canopy to bail out. Probability of his survival, however, was extremely low, and the idea did not appeal too much to the Germans!

Nevertheless, the cheap simplicity of such a single-seater jet does have its appeal - Of course it would get a little more expensive with a landing-gear and sound-proofing, and a launching ramp in the back garden, but we could be off on a short sight-seeing spin around the countryside and then land in a field!

Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

Yes, I have heard of the V-1 Reichenberg. Not a promising concept at all.
The Ohka at least had its visual appeal in my eyes. The Reichenberg does not look quite so nice.

I believe your math calculations are a bit off here.
As I see it:
Range was from 150 to 250 Miles.
Fuel load was 150 Gallons.
Speed was 400 MPH.

That means even on the shorter side of the range scale, we are talking about 1 Mile per Gallon.
at 400 MPH, that would be 400 Gallons per Hour.
On the longer side of the range scale, it would still be burning 240 Gallons per Hour.
In either case, flight times were well under an hour.

Regarding Volksjaeger, the question is still whether there is a way to tune the engine output with altitude.
Without it, it will be pretty hard to get the SL and Altitude speed both correct.

We keep mentioning FS98 and CFS AIR files.
In the case of Propeller Aeroplanes, the difference is obvious: Either Record 505 exists or it does not.
Without it there is no Supercharger.
I am not sure I recognize the distinction with Jet and Rocket Aeroplanes though I suspect that the V-1 is actually using a FS98 format.

- Ivan.

[aleatorylamp]

Hello Ivan,

The Okha at least looked like a plane, but there´s something sleek - albeit quite sinister - about the V1´s looks.
Then, on the other hand, with its cabin, the Reichenberg looks more like a dragster!

V1: OK, I didn´t know it could go up to 250 mi. The range info I´d found stated only 150, so I calculated the "ETA" for 150 miles at 400 mph to be 37.5 minutes.

Yes, be it jet of rocket, both .air files do seem to be FS98 jobs. Also, I haven´t found any information as regards what kind of sound works for rockets. I suppose the Rocket .air file would be the simplest of all - it isn´t even altitude dependent, as liquid or solid rocket fuel don´t need air to burn. Apparently rockets even increase their power with altitude - by 10% at 40000 ft because of the lower air resistance for the exhaust. Moreover, apparently nobody uses the FS rocket .air file - the Jet-turbine .air file is preferred despite all its inaccuracies.

Sparrow:
Apart from speed at altitude being a bit low, S.L. Boost-Speed is also quite low. Thus, raising speeds at altitude would also get that right, and the only inaccurate one would be the non-boost S.L. speed.
There´s no way of getting all four speeds right. It must be something to do with the air density in CFS1´s atmosphere.

Good grief! It´s 10 to 3 a.m. - I´m off to bed. We´d been out for a drink and a hamburger with chips to celebrate my younger daughter´s 20th birthday.

Good night!
Aleatorylamp

[aleatorylamp]

Hello Ivan, Hello Hubbabuba,

I have managed to adjust several parameters to improve yaw, sideslip, and general stability, but this needs further testing, for which I am not qualified, and would appreciate your opinions again as soon as I post the next test .air file.
I do hope it´s not getting heavy on you, all this testing!

The additional reference speeds at altitude given in the pilot´s handbook mentioned by Hubbabubba were indeed IAS speeds. Looking at 16400 ft, I am at the moment only 9 mph under, and at 20000 ft, I am only 20 mph over, so it seems quite OK!

Anyhow, for the moment, I will bother you with just a few comments and one question, so here goes:

Previous results of the last uploaded .air file:
-S.L. normal max. speed perfect at 491 mph.
-S.L. Boost-Burst: 38 mph under at 515 mph.
-20000 ft, normal max. speed was 22 mph slow at 500 mph.
-20000 ft, Boost-Burst speed was 29 mph slow at 533 mph.

After a small Zero Lift Drag reduction to balance out S.L. and Altitude speeds, predictably, a small increment in thrust
was caused - about 60 flb - but the speeds are much better.

For the moment, the 4 Speeds compared to the reference speeds are now as follows:
Normal maximum-continuous thrust is always at 9500 RPM. Throttle % will depend on altitude.
30-second Maximum Boost-Burst is always at 100% throttle.

S.L:
-At _91% throttle: _9500 RPM, 1814 flb and 517 mph (26 mph over) aim: 491 mph
-At 100% throttle: 10100 RPM, 2043 flb and 547 mph (_6 mph under) aim: 553 mph

20000 ft:
-At _83% throttle: _9500 RPM, _965 flb and 509 mph (13 mph under) aim: 522 mph
-At 100% throttle: 10350 RPM, 1178 flb and 556 mph (_6 mph under) aim: 562 mph

So the question is:
Is it better to reduce the 60 flb excess thrust, although it will involve further reduction of Zero Lift Drag, which in turn will increase the gliding ability? At the moment Zero Lift Drag is at 42 in AirEd, which is still just about good enough to slow down the plane when flying in idle.

On the other hand, I remember you saying after your own findings, that at altitude, a certain increase in thrust was necessary to maintain performance. The low S.L. Boost performance also seems to require this. Now, these three speeds have benefited, and have been compensated by this small increment of 60 flb thrust.

What would you think about this?
Thanks again for your time and attention...

I was thinking along the lines of an effective tool for jet engines in the .air file, similar to the propeller tables in CFS. It occurs to me that being able to adjust turbine compression ratio, perhaps by setting the number of stages and maybe also air-intake diameter, would enable fine-tuning the power/altitude curve. Wishfull thinking...

Update: Incidentally, an afterthought on FS rocket testing:
It is THE perfect CFS motor! From S.L., all the way up to far beyond 50000 ft, it retains ALL its Horsepower!!
Not one iota less! I didn´t go further up. Pity it hasn´t got any sound other than the wind from inside the cabin... otherwise it would be the end to all our nightmares! Foot it and go! To infinity and beyond!

Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

Note that at 400 MPH, a 150 mile range is only 22.5 minutes of flight time.
Thus 150 Gallons burned in 22.5 minutes works out to 400 Gallons per Hour.

I still believe the biggest issue that needs to be addressed is the ability to control the thrust at altitude.
Without it, the performance is going to be impossible to match.
You might be able to match maximum speeds; That part is actually pretty easy.
You will not be able to match the climb rates or maneuverability though because these two factors depend on surplus power.

Note that I just made a pretty arrogant comment: Maximum speeds are pretty easy to match.
Note also that the ideas that I am about to suggest are NOT what I consider the ideal way to do things if you really want an AIR file to handle realistically.

If you MUST match maximum speeds but can't alter the power with altitude, here is a way to do it:
1. Increase your Oswald value to about 7000 or so. This will at least cause speed to bleed off in maneuvering.
2. Do another speed test with the new Wing Efficiency value.
My guess is that your maximum speed will be affected only slightly. Your speed bleed-off at lower speeds will increase a bit but probably not as much as you want.
3. Change ALL of the entries in the Mach Drag / Compressibility Table (Record 430) to be Zero.
You want to see how just plain parasitic drag (Zero Lift Drag) affects things.
When I tried this, I found that the Sea Level Speed was increased and became proportionately higher than the speed at altitude.
4. Adjust your Zero Lift Drag so that the maximum speed (at Burst / Sprint setting) matches your specification.
One will match, one will be too high. Don't worry about too high because we will address that later.
5. Use the Mach Drag / Compressibility graph (Record 430) to drop maximum speed wherever it is too high.
Note that this will probably be at Sea Level.
What you are counting on here is that the Speed of Sound is higher at Sea Level than it is further up.
6. Note that Record 430 allows you to create Non-Linear Drag, so if you really want to kill the Gliding ability, raise the values down at lower Mach.
I found in testing with both my Ohka and your Volksjaeger that the place where it needed the most Drag increase was between about 150 MPH and about 300 MPH. Note that 300 MPH is only about Mach 0.4 so increasing drag down that low is not going to affect your maximum speed..... Except if you increase it too high and you can't get past the "Mach Wall".
7. Note that this procedure should get you in the ballpark but there obviously will be a few other tweaks to get the numbers exact.

Incidentally, regarding the V-1:
I decided to adjust some of the values to see if I could get closer to where I thought the values should be.
The Zero Fuel Weight was raised to 3855 Pounds.
The Fuel Capacity was lowered to 150 Gallons.
I adjusted the Fuel Flow down to 270 Gallons per Hour which would give a flight time of 33 Minutes and range of 222 Miles.
Thrust was adjusted down to about 760 which should not change the performance to any significant degree.

- Ivan.

[hubbabubba]

Yesterday was the first birthday of my granddaughter and I only saw your following posts when I came back. I wish I could type as fast as you guys.

I will copy-paste them and try to answer off-line. At a quick glance, I can say;

- The Pilot's handbook is linked in post #38. It says Auszüge aus der Original*Bedienungsanleitung, which was loosely translated by Google as Excerpts from the original operating instructions, but I would say that Bedienungsanleitung is better translated, imho, by User's Manual. As the only possible user would be the one flying it, it is by necessary implication a "Pilot's Hanbook" or notes or guide. The price is 0$, my kind of budget.

- The number I gave are those given by the manual, written by Heinkel and probably revised by their own test pilots. Those are for "safe limits" and not maximum limits. An experience pilot was certainly capable of much higher speeds, as his job was to see "what it got" by "pushing the inside of the envelope". Same thing was going on with Allied a/c, hence the expression "throwing the book aside" in a combat situation.

- Aleatorylamp, take all the time you need. When I came to SOH to get a few pointers for my Bf 108, I was to release in the next days. With Ivan and a few others helping, I finally released it... almost to years later!

[Ivan]

Hello Hubbabubba, Aleatorylamp,

After my prior post, I decided to go read the chapter on the He 162 in Eric Brown's "Wings of the Luftwaffe".
From that chapter, I believe there is sufficient information to have a relatively good target for a flight model.
The aeroplane apparently was not terribly sturdy and structural failures claimed the lives of two test pilots.
The Heinkel pilot died when one wing de-laminated.
The RAF pilot died when he used the rudder to yaw the aeroplane too much (rudder was apparently very sensitive) and the aerodynamic forces first broke off the tailplane and then the entire tail section and the aeroplane tumbled and crashed.

Also from the sounds of it, the aeroplane did NOT have a steerable nose wheel because brakes were needed for ground handling.
Ground handling was also noted as being poor which is another suggestion that the nose wheel was not steerable.

- Ivan.