The Secret Horsepower Race by Calum Douglas (and piston engine discussion)

Hi Pasoleati,



So you have evidence of one incident and agree that it would be ridiculous to draw any conclusion from single incidents.

As stuff you claim something about usually turn out not to support what you say as soon as I can see it for myself, I'll just wait until there's more I can see for myself.

Regards,

Henning (HoHun)
No, I don't agree. Plus let me ask you again: Would a unit commander request that the training programme be shortened to 4.5 hours and 13 landings specifically to save engines without substantial evidence that the failures are caused by the training use?

Finnish National Archives are open to foreigners as well. You are free to gather all the evidence you want. Go ahead.

Meanwhile, some pertinent info. During the year 1943, when 48 G-2s in total (18 of which were replacements for losses arrived, the best engine achieved 86 hours before overhaul. No fewer than 10 engines failed. 16 engines had to be changed. 5 engines had bearing failures which were reclamated and 5 replacements were received. Disastrous performance! For comparison, the Twin Wasp engine of the Myrsky prototype ran over 230 hours before being removed for overhaul. And this at a time when DB engines received "factory tech support" while tech support for the Twin Wasp had ceased years, before.

What is more, regarding 1944, some statistics were compiled including "engine incidents "per flying hour, that is the number of aborted flights due to engine malfunction. The 109 (super-DB!) achieved 181 hours/engine incident. The Buffalo achieved 2100 hours/incident, the Curtiss Hawk did 666 hours/incident and even the crappy Morane 206 hours/incident. The relatively rare Merlin III achieved over 1000 hours/incident (during the service use in whole). The Jumo 211 achieved around 150 hours while the Bramo (Dornier Do 17) over 500 hours.

So of the 4 main fighters in 1944, the worst by far had that masterpiece DB. Again, manufacturer's tech support had ceased for all other 3 years, ago while DB had it most of the year. In fact, even the Klimov VK-105 was found to more reliable than the wonder DB; instead of blowing up, it wore loose over hours and lost some power.
 
Hi Pasoleati,

Finnish National Archives are open to foreigners as well. You are free to gather all the evidence you want. Go ahead.

You want to prove a point, so the burden of proof is entirely yours.

I'll not be responding to the rest of your post because it's a classical diversion (sleight of hand #29 in Schopenhauer's "Eristic Dialectic") to distract from the fact that you can't defend the point you originally made.

Regards,

Henning (HoHun)
 
Reproducing can be more work than a new design. No CAD system can create filets as reliable as the thumb of a mold maker... Are you sure, that the original castings are exactly as designed in the drawings? It wasn't so uncommon in older engine design, that there are some discrapancies.

Are you doning it just for fun, or for a reproduction?

I have the great pleassure, to design a new aero engine...
 
Reproducing can be more work than a new design. No CAD system can create filets as reliable as the thumb of a mold maker... Are you sure, that the original castings are exactly as designed in the drawings? It wasn't so uncommon in older engine design, that there are some discrapancies.

Are you doning it just for fun, or for a reproduction?

I have the great pleassure, to design a new aero engine...
This is just for "fun" at the moment, although it will be a pretty much flightworthy geometry afterwards, if it then did have to go and get made, you would get an original head CAT scanned and do a CAD overlay to check if any ad-hoc mods were made. It should be pretty good however as the drawings are not what we`d call "machining drawings" these days, they dimension very large areas of the casting too, and the pattern makers would have almost certainly carved the patterns using this as the basis. So probably the CAT scan would just confirm/provide a few slightly ambigous dimensions on the drawing, rather than provide any huge changes.
 
I see it in the drawing, they didn't make seperate drawings/designs for mashining and casting those days. Quite a difference to modern 3d designs, here the mold maker really had to interpret a lot. From what I heard (old autmotive world) the design of complex parts was often done with many iterations between the mold makers and the design department.

I hope we get to see a presentation of the final design!
 
I see it in the drawing, they didn't make seperate drawings/designs for mashining and casting those days. Quite a difference to modern 3d designs, here the mold maker really had to interpret a lot. From what I heard (old autmotive world) the design of complex parts was often done with many iterations between the mold makers and the design department.

I hope we get to see a presentation of the final design!
It takes a LONG time to make in 3D from the drawings.

Even the details take ages, most of the threads are all some "extra special fine pitch" etc so I`ve had to draw most of them from scratch.
 
You could have choosen the easier way by starting with the scan, but so it is surly more fun and you make as intended without the disturbance of worn out molds warping etc..

I once redesigned a Diesel cylinder head out of quite tricky scanned data. It was done by another company which scanned the complete (section) of the head, than they cut it into three peaces and arranged the peaces in the exact position like they have been before the cutting. As a result, you get an almost complete inside geometry of the head (exept the slits from cutting). It was relativly cheap compared to x-ray and very precise. I did not a one by one copy, but used the (redesigned) port geometry and quite similar water cores, but with a different spacing and slightly different bolt positions. Even the valve seat geometry could be redesigned out of the scan data.

For obvious reasons, you wouldn't cut an old DB-605 head into peaces...
 
You could have choosen the easier way by starting with the scan, but so it is surly more fun and you make as intended without the disturbance of worn out molds warping etc..

I once redesigned a Diesel cylinder head out of quite tricky scanned data. It was done by another company which scanned the complete (section) of the head, than they cut it into three peaces and arranged the peaces in the exact position like they have been before the cutting. As a result, you get an almost complete inside geometry of the head (exept the slits from cutting). It was relativly cheap compared to x-ray and very precise. I did not a one by one copy, but used the (redesigned) port geometry and quite similar water cores, but with a different spacing and slightly different bolt positions. Even the valve seat geometry could be redesigned out of the scan data.

For obvious reasons, you wouldn't cut an old DB-605 head into peaces...
Might be possible to cut up one from a non-airworthy piece, especially if it's got non-repairable cracks or whatever, so that you could make new cores for castings.
 
Might be possible to cut up one from a non-airworthy piece, especially if it's got non-repairable cracks or whatever, so that you could make new cores for castings.
Its better to CAT scan a new one, with non-ferrous parts, the CAT scan can actually give you discrete 3D zones of the core and metal volumes. It costs a lot, but if you cant afford a CAT scan you DEFINETLY cant afford to make a DB605...:) or indeed any flightworthy WW2 V12.
 
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