Could the life of the DO-217 been extended by replacing the piston engines with turboprop engines?

[maxmwill]

A question, and this is the only folder that I feel I could post this in, as there doesn't seem to be a Luft46 or similar folder, could the DO-217's life have been extended with turboprop engines? The reason I ask, is for a while now, I've been putting together a 1/32 Fw-190D with one of Unicraft's DB-021 resin accessory. I know that most everyone who cares to think about it, has built, in one scale or another, turboprop equipped ME-262s and AR-324, which the Unicraft kit has two sets of resin parts for such. But, I ask myself, what about single engine fighters like the FW-190 or the ME-109?

So, taking the idea further, I'm thinking of doing the same with a Revell 1/48 DO-217E.

Now, with the FW-190 mod, I've been thinking that it could be a strike fighter, or even a heavy fighter bomber. So, what would the 217 be? A high altitude recce, or a high speed medium bomber? Either way, due to the increased fuel consumption(in my experience, turbine engines, including turboprop, are thirstier than piston engines), so there'll have to be external tanks, unless it's a recce version, as there won't be any ordinance, so there'd be increased internal tanks.

 

[swampyankee]

Why would one bother doing that? By the time turboprops came out, so did much aircraft much better than the Do217 or FW190.

 

[Shortround6]

could the DO-217's life have been extended with turboprop engines?

Yes, if the Germans could have built a turbo prop.

If you can't make jets (ones that last more than 10-20 hours) due to problems with turbine blades you can't make turbo props which need a lot more turbine blades.

 

[Admiral Beez]

Why would one bother doing that? By the time turboprops came out, so did much aircraft much better than the Do217 or FW190.

Depends what the intended role was. Plenty of aircraft that started off as WW2 era piston-powered designs went onto turboprop power later. Such as the Avro Shackleton and DC-4 conversions, and new builds like the P-51 inspired Cavalier Mustang.

 

[Graeme]

Plenty of aircraft that started off as WW2 era piston-powered designs went onto turboprop power later. Such as the Avro Shackleton and DC-4 conversions,

Shackleton with turboprops?
Turboprop conversions of the Douglas DC-4?

 

[Graeme]

Probably the best known Dornier with turboprops...

 

[swampyankee]

In a similar vein, there was a turboprop T-28. There were also Convair 440s and Martin 4-0-4s converted to turboprops.

The best known turboprop Dornier is probably the 328.

 

[Graeme]

The best known turboprop Dornier is probably the 328.

I was thinking in terms of Dornier from WW2 - but yeah.

I Martin 4-0-4s converted to turboprops.

Do you have any photos of the Martin 404 - with turboprops?

 

[Shortround6]

"Convair CV-240-21 TurbolinerTurboprop-powered conversion fitted with Allison T38 engines. It became the first turboprop airliner to fly in the United States (on December 29, 1950), but problems with the engines resulted in development being terminated. Used as a test bed before being converted back to piston power."

Conversion from a Convair CV-340 aircraft with two Napier Eland turboprop engines in place of the piston engines. Six aircraft were converted by Napier for Allegheny Airlines.[15] First flight February 9, 1955.[16] When Rolls Royce purchased Napier, the Eland program was terminated, and the Allegheny aircraft were converted back to piston power, but were later converted to Convair 580s with Allison turbo props.

Convair CV-580 Conversion from Convair CV-340 (Allison Prop-Jet Convair 340) or CV-440 aircraft with two Allison 501 D13D/H turboprop engines with four-blade propellers, in place of piston engines with three-blade propellers, an enlarged vertical fin and modified horizontal stabilizers. The first such conversion flew on January 19 1960, although it was not until June 1964 that a converted aircraft entered service.

Convair's own conversion program involved Rolls Royce Darts, and the first of these flew on May 2 1965.

Not sure how any of these support the idea of a WW II turbo prop or even a Korean war turboprop.

 

[swampyankee]

I was thinking in terms of Dornier from WW2 - but yeah.



Do you have any photos of the Martin 404 - with turboprops?

I could have sworn there were turboprop Martin 4-0-4s; it seems there weren't.

 

[wuzak]

Depends what the intended role was. Plenty of aircraft that started off as WW2 era piston-powered designs went onto turboprop power later. Such as the Avro Shackleton and DC-4 conversions, and new builds like the P-51 inspired Cavalier Mustang.

No sure about Shackleton turboprop.

The Shackleton did fly with a Napier Nomad turbo-compound in the nose to test the engine. But that's not a turboprop.

The Lancaster flew with a few turbojets and turboprops as a test bed.

Sometimes a single turboprop was in the nose, and at least one had two in the outer engine positions, trialing the Armstrong Siddeley Python.

https://www.agefotostock.com/age/en/Stock-Images/Rights-Managed/MEV-10838178

http://1000aircraftphotos.com/Contributions/Braas/9314L.jpg

1000aircraftphotos.com Main Menu

 

[wuzak]

And, of course, the Avro Lincoln

Avro Lincoln - Wikipedia

 

[Thos9]

A question, and this is the only folder that I feel I could post this in, as there doesn't seem to be a Luft46 or similar folder, could the DO-217's life have been extended with turboprop engines? The reason I ask, is for a while now, I've been putting together a 1/32 Fw-190D with one of Unicraft's DB-021 resin accessory. I know that most everyone who cares to think about it, has built, in one scale or another, turboprop equipped ME-262s and AR-324, which the Unicraft kit has two sets of resin parts for such. But, I ask myself, what about single engine fighters like the FW-190 or the ME-109?

So, taking the idea further, I'm thinking of doing the same with a Revell 1/48 DO-217E.

Now, with the FW-190 mod, I've been thinking that it could be a strike fighter, or even a heavy fighter bomber. So, what would the 217 be? A high altitude recce, or a high speed medium bomber? Either way, due to the increased fuel consumption(in my experience, turbine engines, including turboprop, are thirstier than piston engines), so there'll have to be external tanks, unless it's a recce version, as there won't be any ordinance, so there'd be increased internal tanks.

The Do 217 was underpowered, no question, but no turboprop was available by war's end. However the piston Jumo 222, even derated from 2500 to 2200 hp for reliability, would have cured this weakness and could have made for a better bomber than the Ju 88 and its derivatives.

 

[Koopernic]

A turboprop Dornier Do 217 would definitely produce a viable aircraft. Shortly after the D-Day landings production of almost all Luftwaffe bombers ended and many units had their aircraft scrapped with their crews transferred to fighter bombers. Production of the Me 410, Do 217 ended however Ju 88/388 continued. This was simply due to the fact that mass production of the Ju 88 series was in the range of 15000 versus 1300 or so for the Do 217 and so the Ju 88/388 was more efficient to produce.

Compared to the Ju 88/388 for the same power the Do 217M at 348mph was as fast as the Ju 88 and much faster with bombs since the Do 217 had a cavernous bomb bay that could take over 4400lbs, in fact it could take full length torpedoes. The Ju 88 had to carry bombs externally or in a panier, it did have two small bomb bays ahead and after the spar but they were incapable of bombs larger than 70kg so was usually used for fuel tanks. The Do 217 was also suitable for carry winged guided weapons on its outer fuel tank stations which the Ju 88/388 generally lacked. For instance the Henschel Hs 293, Hs 294, Hs 295 and the Blohm & Voss BV 246. The Zitterochen was the first supersonic, winged, and guided missile. Intended for use against ground targets, it had small triangular wings and two rocket motors. It did not enter production but should have fitted into the Do 217 bomb bay.

There were three turboprop engines in development:
1 Officially known as the 109-021 (PTL) or Heinkel Hirth HeS 021 also known as the Daimler Benz DB 021 which was a development of the HeS 011 turbojet (was benching at 1153 kg in Feb 1945 but was to ready for flight testing around June for the Ta 183). Intended for long range versions of the Me 262, Arado 234 it is the most likely engine for the Do 217M turboprop.

All sources from Anthony Kay "German Jet Engine and Gas Turbine Development"
British BIOS Repot Specification: Power at Sea Level Static 1950shp, jet thrust 585kP (ie kg) which is quoted as 2400 ehp.
Daimler Benz Graph and Spec: Power at Sea Level at 497mph/800kmh 3300ehp
Power 10,000m (32,800ft) at 497mph/800kmh 1620ehp
Power 12,000m (39,600ft) at 497mph/800kmh 1620ehp
An American Report gives: Power at Sea Level 2000 shp, 790kg thrust at 466mph (this would work out at 4250ehp)

These reports are not actually incongruent. It is customary to use the equation P =Fv (power = thrust x velocity) to calculate the ehp 'equivalent horse power'. The Germans were using 497/800kmh as the standard turbo prop speed for calculation. In US/British circles 550 feet/sec or 167m/s or 325 knots or 374mph because 1 horse power = 550 foot pounds per second. Furthermore the thrust of an engine can be calculated.

In fact taking the British figures and correcting them at 325knots gives 1250 which added to the 1950 gives the 3300ehp of the Daimler Benz report.


2 Jumo 022 which was a development of the Jumo 012 turbojet. Assembly of the prototype turbojet had begun.
Kay gives
4600 ehp at sea level static (separate figures not available)
3500 shp plus 1200kg thrust approximately 9500ehp at 497/800kmh.

3 BMW 028 which was a development of the BMW 018 turbojet. Assembly of the prototype turbojet had begun.
Jet Trust at 800/kmh 1425kg and 7000shp equal to about 12,600ehp.

The Do 217M was fast, 348mph. Lets look at Do 217 performance:
Do 217E2 Speed 320 mph At 13,120ft Max Cruising Speed 286
BMW 801ML 1560hp
Do 217K Speed 328 mph At 22,310ft Max Cruising Speed 306 (Some sources state 333mph)
BMW 801 801D2 1700hp
Do 217M 560 km/h (348 mph; 300 kn) at 5,700 m (18,700 ft)
475 km/h (295 mph, 256 kn) at sea level
DB603A 1750hp.

Links:
Dornier Do 217
Dornier Do 217
The Dornier Do 217
Do-217 Medium Bomber and Reconnaissance aircraft Dornier - Luftwaffe

So its worth doing some calculations using a cube root law.

If the 1750 DB603A was replaced with the DB603 L/LA of 2250hp
Speed increase at sea level with 2250hp instead of 1750 using a cube root law from 296ph->322mph.
Speed increase at 5700m/18700ft for same percentage increase 348->378.

If DB603L/LA used with increased boost with at sea level 2400hp 296->328
Speed increase at 5700m/18700ft for same percentage increase 348->386.

If Jumo 222E/F of 3000hp was used instead of 1750 increase in speed at seal level 296->354mph
Speed increase at 5700m/18700ft for same percentage increase 348->416mph.

Actual speed increase at 25,000ft would be about 25 mph for all these cases due to higher full throttle height due to the 2 stage superchargers on DB603L/LA and Jumo 222 E/F, so over 440mph.

For a 109-021 of 3300ehp
Speed at sea level 296mph->365mph
At higher altitudes speeds of at least 440mph are going to be achievable.

I immagine a stand off anti shipping bomber using guided weapons opperated at night would be its main use. The Luftwaffe was already able to carry out blind bombing attacks against shipping using Hohtenweil radar using bombs or torpedoes. Unfortunatly the Fw 200 wasn't the best platform.

 

[maxmwill]

"I immagine a stand off anti shipping bomber using guided weapons opperated at night would be its main use. The Luftwaffe was already able to carry out blind bombing attacks against shipping using Hohtenweil radar using bombs or torpedoes. Unfortunatly the Fw 200 wasnt the best platform."

It's interesting that you mention that, because There was the Do217W as well as the DO217G, which were float plane proposals, which, while making for more interesting discussions, might've been useful. And from a modelling standpoint, would make for an interesting comparison with the He115.

 

[Koopernic]

The Do 217 was underpowered, no question, but no turboprop was available by war's end. However the piston Jumo 222, even derated from 2500 to 2200 hp for reliability, would have cured this weakness and could have made for a better bomber than the Ju 88 and its derivatives.

Kay gives the HeS 011 ie RLM 109-011 benching at 1153kg thrust in Jan/Feb 1945. Heinkel Hirth had planed a Turboprop version HeS 021 (ie RLM 109-021 but the work was pushed onto Daimler Benz to spread workload. The idea was to keep the hot part of the engine the same but add a 3rd turbine to the existing 2 so as to extract around half the available power. Most of the work would be in adding the additional turbine, strengthening bearings and shaft and adding a gearbox and developing prop pitch controls. A 6 blade (2 x 3) counter rotating propeller was planed for single engine aircraft and a single 6 blade pop for twins. Some kind of prototype probably could have been ready before the end of 1945.

 

[Thos9]

Kay gives the HeS 011 ie RLM 109-011 benching at 1153kg thrust in Jan/Feb 1945.

I can't find this in Kay. Dr Max Bentele, who was in charge of development, records in his autobiography "Engine Revolutions" that in December 1944 best performance figures were achieved as follows: Thrust 1333kp at 10,205 rpm, pr 4.2, mass flow 29 kg/sec, turbine inlet temperature 775C, sfc 1.35.

 

[dedalos]

The most realistic improvement for the Do217 , was the use of Db 610. As it was suggested in the Do 317B programme. The basic Db610 was free of problems after midwar, and it would only require a good nacelle design. The resulting aircraft would be unstopable on the eastern front even in daylight, and a hard opponent for the western night fighters. But without fuel , it was pointless . But true , the Do217 was really good basic design.