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Early WW2 engines with two stage superchargers - DB 601C/D

 
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rinkol



Joined: 13 Jul 2003
Posts: 37

PostPosted: Mon Jul 17, 2006 20:06    Post subject: Early WW2 engines with two stage superchargers - DB 601C/D Reply with quote

These engines were reported to be two stage supercharged variants of the DB 601, differing only in the propeller reduction gear ratio. Apparently, the DB 601 D expected to be of some importance as orders were definitely placed for atl least a small number of engines and it was planned for installation in the HS 130 high altitude reconnaisance aircraft. However, this development line was abandoned early in the war. The published specifications include a power output of 1300 hp and a rated altitude of 8000 m. The DB 601E/F, which did go into large scale production, had a slightly higher power rating and 25 kg lower weight, but the rated altitude of 4800 m was considerably lower.

Is there any information available as to what the specific problems were?

Robert
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jwells



Joined: 16 Sep 2003
Posts: 55
Location: Victoria, AUSTRALIA

PostPosted: Sun Aug 20, 2006 18:13    Post subject: DB 601 C/D Reply with quote

This is a very good question - one which has puzzled me for some time. I've got three references to this but they are all the same! It would seem that some sort of master listing of all the Daimler-Benz WWII engines was released, presumably just after the War and that everyone has used it ever since. The most complete copy of this list occurs in 'Power To Fly' by Setright. It runs to six pages.

Just where some diagrammatic info on the set-up used or proposed could be obtained is something I would be very interested to hear about.

Jerry W.
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jwells



Joined: 16 Sep 2003
Posts: 55
Location: Victoria, AUSTRALIA

PostPosted: Sat Feb 17, 2007 17:00    Post subject: DB 601 C/D Two-Stage Engine. Reply with quote

I recently came across a patent that was filed in Great Britain by Daimler-Benz AG in 1937 which almost certainly covers the design and control system for this engine.

The number of the doco is GB480,236 and it contains two very good drawings, one of which shows the usual supercharger on the left side of the engine but with a matching unit on the right hand side. Air enters the LHS unit in the usual manner but the discharge goes via a pipe across the back of the motor to enter the second blower from the side, so there would have been a bump in the cowling on the RHS.

Each supercharger is driven by a fluid coupling - just a single unit in each case rather than the duplex units used in the other engine models and the control valving is arranged so that the LHS s/c comes into operation before the RHS unit. The valves are controlled by an aneroid capsules and open sequentially.

The patent doco, which is only four pages, can be downloaded free from gb.espacenet.com (note, NO www).

What I can't find is a photo or drawing of the Henschel 128 high-altitude reconnaissance aircraft for which the DB601C/D was intended for.

Jerry W.
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rinkol



Joined: 13 Jul 2003
Posts: 37

PostPosted: Sun Feb 18, 2007 18:18    Post subject: Reply with quote

Good find!

Interestingly, the two stage superchargers used in the DB 605L and DB 603L as shown in Janes had both blowers on one side (and apparently sharing a common drive shaft). I wonder if there were some feedback stability issues associated with the boost control for the arrangement described in the patent.

Green's "Warplanes of the Third Reich" has a pair of small photographs of the HS 128V2 and a line drawing under the section on the HS 130. From the description and line drawings, the HS 130A was similar in appearance except for having a retractable undercarriage and different wingspan.

Robert
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jwells



Joined: 16 Sep 2003
Posts: 55
Location: Victoria, AUSTRALIA

PostPosted: Mon Feb 19, 2007 18:53    Post subject: DB600 series - 2-Stage S/C. Reply with quote

What is not pointed out in "Janes" is that the DB627 (1942-44) also had a supercharger unit on each side of the engine, like the DB601 C/D.

In this case, the air was transferred from the right hand side to the LHS, then through an intercooler before going to the induction manifold.

With either both stages on the one side or one stage on each side, the increase in the width of the engine must have been considerable.

There is some additional info on the DB 601 C/D via Patent No. US 2,238,889 which was first filed in Germany in 1935. This actually gives the inventor, Karl Kollmann credit for the work, rather than just listing Daimler-benz.

This patent describes the two side-mounted blowers and, in particular, gives details of the bevel-gear drive arrangement that ensures the two impellers rotate in the same direction.

Fluid couplings are used to control each supercharger; in this case, the usual DB duplex units are used.

What is really interesting is that in some of the drawings, the double supercharger set-up is shown as being attached to an inverted V-12 engine.

However, in Fig. 2, there appears to be a major error in that the air discharge from the 1st-stage blower is from the rear of the unit while the outlet from the 2nd-stage s/c is from the front of the volute (scroll). This could only be possible if the two impellers could rotate in opposite directions, which the described gearing doesn't allow! Fig. 1, on the other hand, appears to show air discharge from the rear of both units.

Could somebody check this out for me?

Jerry W.
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rinkol



Joined: 13 Jul 2003
Posts: 37

PostPosted: Tue Feb 20, 2007 19:47    Post subject: Reply with quote

There is a curious photograph of a "twin supercharger prototype ... DB 601" at

http://www.warbirdsresourcegroup.org/LRG/db601.html

The layout resembles the later DB 628 and I was wondering whether the figure was mis-captioned. However, it is noticeably different in appearance than the DB 628 photograph I've seen.

I doubt that this is the DB 601D as the front supercharger and ducting would add considerable weight and the DB 601C/D specifications in "Flugmotoren und Strahltriebwerke" give a weight that is only 25 kg over that of the DB 601E/F, which appear to be the closest equivalent among the single stage engines. The DB 628 was about 140 kg heavier than the DB 605A.

This last reference also mentions a DB 600E/F "versuchsmotor mit doppellader" and a 7000 m rated altitude.

Robert
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cdouglas



Joined: 17 Jan 2015
Posts: 5
Location: Scotland

PostPosted: Sat Jan 14, 2017 05:54    Post subject: Kollmann supercharger patent Reply with quote

Hi Jerry,
The illustration "Fig 2", may have been drawn incorrectly for a setup
with two rotors geared to rotate in the same direction. However,
it is quite difficult to tell, and may well be the case that it is meant to
show that the blower outlet from the LHS blower exits at the upper side of the volute and infers that this pipe passing to the bypass valve, passes
(in side view) diagonally over the top of the volute (in which case it works).

It is quite difficult to tell from the sketch in the patent. But certainly the
pipes WOULD have to exit the volutes at opposing ends when rotating in the same direction but mounted back-back; as you correctly point out.

So it is either an error in the drawing, or just that it could have done with a side-view to show that properly.

I have Kollmann`s technical memiors which he wrote in 1947, and I can assure you he would have known this himself ! Smile

Kind Regards

Calum
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