Heinkel He-162 "Spatz", 1944

[Ivan]

Fuel Capacities

Hello Hubbabubba, Aleatorylamp,

I believe the actual Fuel capacities were
475 KG in a Fuselage Tank
200 KG split into two Wing Tanks

I would treat the starting fuel as something like lubricating oil or MW50 as far as weight is concerned.
It also sounds to me like the fuel use for warm up and takeoff are just a comment about what amount of the main fuel capacity was spent for those activities.

Hello Hubbabubba,

The problem here is that although we know the weight of the fuel, we need to figure out the fuel tank capacities from weight and density. As you pointed out, we need volume for the AIR file.

Hello Aleatorylamp,

Now I can see the Wing Tip / Outer Wing Component not working.
Regarding finding data, it was just a matter of varying the searches a little bit.
Note the engine thrust versus altitude entries.
Note also that the speeds at various altitudes are mostly estimates.
I wish I could find this much data on other aeroplanes.

I figure that before even considering working on a CFS Jet, I need to figure out how to vary power with altitude and being able to set up an Afterburner.

- Ivan.

 

[aleatorylamp]

Hello Hubbabubba,
Thanks for the extra information. It seems there´s lots of contradictory data around!

The nearest that comes to my speculated 893 L resulting from my supposition of the J2 German Synthetic Diesel density being 7.3, is the quantity you quoted in litres: 875 L = 231.1505 gal (Wings of the Luwtwaffe).

The following page lists specific weights for several different fuels:

http://www.engineeringtoolbox.com/fu...mes-d_166.html

I went for DIESEL 1D at 54.6 lb/cu.ft (7.3 lb/USG) as it seemed the closest.
DIESEL 4D is heavier and gives 8 lb/USG, and the equivalent in Litres would only be 840, so I discarded it, and others seemed a bit light.

Maybe the correct density for the German J2 Diesel can be calculated with the 875L (231 USG) weighing 777 Kilos, and then we could possibly go with the 231 USG Tankage. Is this plausible or is it just going round in circles?

As regards the J1 petrol for the Riedel starter-motor, I realized that (it was only 2L) and edited it out of the post a short while ago.

Interesting, your info on how the "burst" was controlled, and that it also served for engine start-up.

Cheers,
Aleatorylamp

 

[aleatorylamp]

Hello Ivan,
Your post came in as I was writing!
From your comments, I suppose then that 875 Litres (231 USG) seem closest.
The weight given in the PDF document would be the 675+80+22=777 Kg = 1713 lb, giving a specific weight of 7.41 lb/USG.
...please directly shoot me if I´m wrong...

As regards adjusting power to altitude, I hope I am wrong, but I haven´t seen any parameter in the jet .air file which I can understand as being able to handle this, and as there is no WEP control either, afterburners don´t seem to be covered. Thus, in my limited capacity of a beginner with .air files, my view is that we are landed with what there is! However, I think we can get a decent enough approximation.

Update: I just conducted a high-altitude test at 36000 ft and you do have a point here.
Speed is only slightly low and thrust is somewhat high.
- Wings of the Luftwasse quotes Max. thrust at 36000 ft and 497 mph as 372 flb.
- The American .pdf states 265 flb for normal max. thrust, and 332 flb for 30 sec max. thrust.
- In my case I´m getting considerably more thrust: 630 flb and 485 mph with boost, but it takes much longer than 30 sec. to get there. Then, with normal thrust at 75% throttle, thrust is 483 flb at a little over 400 mph.

Cheers,
Aleatorylamp

 

[Ivan]

Hello Aleatorylamp,

I guess I had better see if there is such thing as a CFS Jet file format. Perhaps there were additions for altitude performance there????
Without an afterburner, most of the projects that would have been interesting to me just can't be built.
It seems like we are limited to nothing later than a MiG-17 and a F-86 or similar. Perhaps I will try the Me-262 anyway
I believe I already have some pretty good drawings in a book.

Regarding fuel capacities and weight. I don't really agree with your conclusion but it is certainly within range.
Fuel Oil (Heating and Diesel) is typically in the range of

Diesel ------------- 0.81 to 0.936 grams / mL
Kerosene (Coal)--- 0.81 to 0.936 grams / mL This is typical Coal derived.
JP4 ---------------- 0.751 to 0.802 grams / mL


For JP4, the weight per Gallon would range from 6.267 pounds to 6.693 pounds
The low end of the weight range for Diesel is near the high end for JP4.
The high end of weight of Diesel per Gallon would be 7.811 pounds which is barely lighter than Water.

I don't believe the weight of Starting Fuel should be included.
I also believe that the fuel used for warm up is actually part of the regular supply, otherwise other sources would also have included it.

If the 875 Liters of fuel weighed 675 Kg, then it would be 0.771 grams / mL which is right in the middle of the range for JP4.
That would 6.438 pounds per Gallon....

- Ivan.

 

[aleatorylamp]

Hello Ivan,

Well, for the moment at least the Me262 engines are within the possibilities for an acceptable CFS .air file then.

As regards the fuel type and quantity for the He162, my 777 kg and 875 L calculation comes from page 15 of the document you sent (.pdf page 17), which mentions 675 kg of fuel at take-off, plus 80 additional ones for warm-up and take-off, as well as 22 for startup. Petrol for the Riedel starter motor was only 2L so I don´t think it is included here. Hence my 7.41 lb/gal calculation. However, if you feel it is more correct to calculate on the basis of the 675 kg take-off fuel, it´s better as with 6.4 lb/gal the plane a bit lighter. No problem!

I´ve managed to put in the canopy frame in 2D and I´m finishing the bleeds at the exhaust nozzle, so the model improvements are nearing their finishing phase.

Cheers,
Aleatorylamp

 

[Ivan]

Hello Aleatorylamp,

Yes, the Messerschmitt 262 is a possibility. I just have so many other projects that are ALMOST done that I feel that I should complete them first. Many have been stuck for years. I figure that if I complete the gauges for the Lightning and Mitchell, then I will actually have learned something which is my main goal these days. There are also t least three others that are ready for release but for some tedious texturing tasks....

Regarding weight of fuel, just remember: This is YOUR aeroplane. It isn't mine. I do what I want. You use what parameters you believe to be correct. The sources I found were done pretty quickly and I barely skimmed over the report you are quoting from.
The Russian video actually gives much different numbers than the others, so with all the conflicting sources, you get to decide which is correct. It has to be whatever you are satisfied with.
If this were my project, I would be using a notes / data document. You know the format I typically use. I obviously have not done that here. What do you notes say? Which sources are in agreement and which are in conflict? Can you deduce something from other weight data such as basic and take-off weights?

In some areas of this project, I believe I can give some pretty good advice such as in AF99 problem solving or in how to tune Flight Models, but what to include in the projects is you decision.

- Ivan.

 

[aleatorylamp]

Hello Ivan,

Thanks for your comments, and thank you very much for your continued and effective advice!
There is not really much difference in weight anyway, so it´s not an important issue.

I´ve just put in the new brakes ( -17500) which, at least for German standards, were great, and the effect is really striking! You can see the nose coming down on the front gear suspension. A very nice discovery.

Finally, I´ve been able to achieve several improvements on the model, some of which you had conveniently pointed out: Canopy glass colour, canopy frame, engine base and exhaust nozzle bleedthroughs, and everything is quite satisfactory. The build has come out much cleaner than before. Parts count is now at 115.4%.

Here´s a collection of screenshots as eye-candy meanwhile.

As regards performance tuning, I´ve managed to get max. Boost thrusts and speeds for Sea Level and for 20000 ft exact, and also, the normal S.L. speed is only 5 mph over, so the performance envelope upto that altitude is quite satisfactory.
Not so much at 36000 ft, hwoever: Max. boost speed is 37 mph slow, and normal speed is quite a bit slower, but there´s nothing much to be done about that.

Cheers,
Aleatorylamp

 

[hubbabubba]

Hi guys!
It took me one day to update my three W7 machines, so I have, as always, some catch-up to do.


Ok, I've pretty much found what I needed for the fuel gauge capacity and I will pass along the information as it could help for the AIR file. All results are in Litres (or Liters for Americans) and are converted in US gallons. I have used many methods to get those numbers; readings in capacity, weight and volume. First hurdle was to determine the specific weight of J2 Kraftstoff. The most useful information came from a Polish-speaking forum where such a discussion took place at http://www.dws.org.pl/viewtopic.php?p=1387723#p1387723, which comes to prove that splitting hair is an international sport. By dividing the fuel weight by the capacity of the fuel tanks of a Me 262, they came to 0.82Kg/L (even more precisely 0.81725883Kg/L), so J2 was a heavy kerosene-parafin (0.78–0.81Kg/L in Wikipedia) or a light diesel (0.832 kg/L in Wikipedia). Acording to http://www.fischer-tropsch.org/prim...VY/tech_rpt_145_45/rpt_145_45_conclusions.htm; "Jet fuels were being produced in Germany at a rate of ca. 1,000 barrels per day in 1944. The fuel was a mixture of gasoline and diesel oil fractions. The specifications for jet fuel were lenient; no unusual quality was demanded and no unusual specifications were forthcoming.".


Funny tidbit of quirky info; the Spatz was to use B4 aviation fuel for logistic simplicity but, due to shortages of aviation fuel, it was "converted" to jet fuel as the first production aircraft were about to be delivered! (NASM, 3391/16, Technische Direktion: 162 Wochenbericht vom 26 Februar–4. März 1945.).


First, the now (in)famous He 162 Bedienungsanleitung.
Maximum fuel load was 1520 L (401.5415 gal) and "light" load 750 L (198.129 gal). I doubt that the maximum load was a current practice for weight and balance reasons. The aircraft "wet wing" concept was troublesome and overloading them was a recipe for disaster as they continually leaked despite all efforts to remedy the situation. The extra inflatable reserve was for long-haul ferrying. The filling method is revealing; from the fuel cap on the upper left wing! So, whatever how much you put in it, you had to fill the main tank before getting any fuel in the wings. Let's leave it at that for now.


Second, the Wikipedia, at 695 Litre (183.5996 gal). I sensed a "main tank only" in that unexplained data.


Third. From WW2 Warbirds (http://www.ww2warbirds.net/ww2htmls/heinhe162.html), at 950 Litres. It only says "internal capacity" without tanks' position.


Fourth. Wings of the Lufwaffe by Brown, at 875 Litres (231.1505 gal). That measure is not verbatim but mentionned in the cut-away schematic's list. He flew himself the bird with "only" 450 Litres (118.8774 gal).


Fifth. Monogram Close-up 11, at 980 Litres (258.8886 gal). It not only indicates the tanks' capacities, but also shows a schematic side view with their position, size and piping connection. Well researched but with a few mistakes (like the non-existant flap indicator). Calculating capacity by using a composite of this source with a Polish book gave me impossible numbers for the main tank, so far-off that I scrapped everything before even trying to measure wings' capacity.


Sixth. From http://www.bredow-web.de/RAF_Museum/Heinkel_He_162/heinkel_he_162.html, which gives 475 Kg. Assuming that the "middle of the road" mention of 0.82 Kg/L of the Polish forum is correct (and I think it is), it makes for 579 Litres (152.9556 gal).


Seventh (and final). Ivan educated guess at 675 Kg, or 823 Litres (217 gal).


THe first number should be, logically, the right one but, quite frankly, I can't believe that the wings could hold 700L on top of the 650L (+170L if the reserve is installed). A bit of "theoretical wishful thinking" must have taken place here!


So, in conclusion, I will try to find a suitable 700L gauge and I think that, "filled to the rim", it shouldn't go more than 950L.


Still an educated guess, but a "ball park" figure.


Regards,
Hubbabubba


P.S.- While waiting for the uploads, I was still working on the panel. The AFN2 is almost ready, and as close as I could go to the real deal.

 

[Ivan]

Hello Hubbabubba, Aleatorylamp,

The German site for the RAF Museum is the same one as I posted earlier and is where I believe the data confirms my guess as to the fuel load.

Please pardon my very mediocre German. I am sure Aleatorylamp can read these data better than I can.

Note that the Abfluggewicht (Away-Flying Weight or Take-Off Weight) is listed as either 2495 KG in one table entry and for performance specifications is listed as 2500 KG (probably rounded off).

Note further on that at a Take-Off weight of 2700 KG, there is 200 KG of additional fuel (Zusatzkraftstoff). For there to be no additional weight for other equipment would imply that only an internal tank(S) was filled that was left empty at 2500 KG.

From your 0.82 KG / Liter value, that would be 825 Liters of fuel for 675 KG which is not too far from what is stated in Wings of the Luftwaffe. Then again, perhaps the tanks could hold more fuel but it was just never filled to capacity as it typically was not in the P-51D Mustang.

To me, the light fuel load of 475 KG sounds like it would be with just the fuselage tank filled and if that is the case, the capacity would be 581 Liters. This seems like a strange number to someone expecting something nice and even but eve with the 0.771 value I guessed, it would be 616 Liters which is still not even....

Since there was only a fuel gauge on the main tank, it seems to me like 580 or 600 Liters would be sufficient for a gauge.

- Ivan.

 

[aleatorylamp]

Hello Ivan, Hello Hubabubba,
Thanks for your research efforts. Excellent!
So we have the density of J2 at 6.82 lb/gal, and that the tank capacity accounted for fuel used for warming up and taxiing prior to take-off, and that these two weights were reflected in some of the inspection sheets.
Then, from what both of you are saying, I gather that the tank capacity in the .air file would be OK at 231 USG - correct me if I´m wrong!
I´m looking forward to the panel! No hurry, of course!
Cheers,
Aleatorylamp

 

[hubbabubba]

Well, it should be 231.1505 USG but I will let it go...

But not the density, it should be 6.843232, go see http://www.endmemo.com/sconvert/kg_llb_galus.php

btw, this site is now in my favorites - http://www.endmemo.com/convert/

Funny thing is that, liter for liter, J2 got a better "mileage" than B4, the thrust being slightly less but the burning being much longer, which translated in longer flight duration. The only disadvantage was longer throttle response.

Actually, German jet engine could burn pretty much anything, alcohol, turpentine, you name it!

 

[aleatorylamp]

Hello Hubbabubba,m
OK, thanks very much for confirming. Nice converter site!
I´m a bit confused as to the density:
I entered 0.81725883 Kg/L that you said was more exact, and I got 6.820355 lb/USG...
Anyway, 0.02 is no big deal!
Cheers,
Aleatorylamp

 

[hubbabubba]

I was using 0.82Kg/L. I'm not that confident about the Pols' calculation, and the precision of what was basically a very half-hazard fuel formula.

 

[hubbabubba]

Contradictions, Aleatorylamp? What contradictions?

In a document dated mid-october '44, Heinkel (Baubeschreibung) the fuel tanks were to be of 640L in the fuselage and 325L in the "wet wing". But Wikipedia says that the wing tank was never put on production and the main tank increased to 695L. All fine...

...then: why does Eric "Winkle" Brown does clearly mention that the aircraft he flew had the wet wing? The fuel cap is even depicted in the schematic cut-away... naturally in the wing.

Geeee...

P.S.- How come brown knew that his wing tank was emptied? He says he saw the fuel gauge needle declined, simple?
Not so simple; he took off with 450L in an aircraft having a main tank containing 695L, the wing tank feeding by simple gravity the main tank. See where it doesn't make sense? Well, now, I do.
If I had hairs to spare, I would be pulling them right now!

 

[aleatorylamp]

Hello Hubbabubba,
Well, I´m afraid I can´t quite follow your line of thought.
We know that apart from the 2 different main tank sizes, which must have had their correspondingly different fuel gauges, there were also wing-tanks, because Eric Brown was testing a unit with a small main tank and two wing tanks.
Could it be that the initial centre wing tank was the one that wasn´t built, and that each wing had a small tank, prior to the planned completely wet wings that were never used?
So what total fuel capacity would you suggest we implement for the little bird?
I wonder...
Cheers,
Aleatoryulamp

 

[hubbabubba]

If the main tank had a capacity of 695L, then a 450L fuel load would be all in the main tank. Wing tank, no matter its capacity, was only feeding the main tank by gravity. So anything under 695L would mean an empty wing tank. See it now?

 

[Ivan]

Hello Hubbabubba, Aleatorylamp,

just throw a bit more confusion into the mix:

Eric Brown's book Wings of the Luftwaffe states that the fuel for the Me 262 was mostly 87 Octane (probably B-4 fuel) with 5 percent lubricating oil.
The Riedel starter ran off of the same fuel... That is not quite the same (Kraft)Stoff that was used in the He-162, so perhaps the Me 262's fuel specifications have less relationship to the He-162's fuel than first thought.

I figured if I was to consider building a Me 262, I should probably do some reading there.

- Ivan.

 

[aleatorylamp]

Hello Ivan, hello Hubbabubba,
Interesting that the J2 compared to B4 gave more range and less power. Like diesel and gasoline does in cars.
It appears that if J2 wasn´t available they coud take B4 mixing in some with lubricating oil.
Anyway, Eric Brown´s 450 Litres won´t help me very much as regards tank capacities. When I read his report, I thought or he was flying on partial fuel capacity, or the plane had the small main tank fitted.
Anyway, then I´ll continue with the 231 USG total capacities agreed before.
Cheers,
Aleatorylamp

 

[hubbabubba]

Hi guys!

Yesterday, I went to a brunch and only came back in the late afternoon. But I had time to do the Großhöhenmesser, easier than I thought it would be.

A good document on jet fuel is THIS ONE. B4 was used when J2 was not available, it is even mentioned in the He 162 Bedienungsanleitung PDF as a possible replacement.

The left half of the main panel is there and the backdrop is pretty much done. Will send you both, Ivan and Aleatorylamp, a "teaser" tonight.

Back to ...hum... "work"...

 

[aleatorylamp]

Hello Hubbabubba,
A good find, the Me262 document! Very interesting.
Thanks for the He162 panel preview. It certainly is a beautiful piece of work.
I was wondering if, given the quality of the craftsmanship, this panel would warrant a separate, individual upload. This way it would stand out the way it deserves, dont´you think?
Cheers,
Aleatorylamp