Fokker D.XXI in Dutch service

Hello
I dig a bit deeper into FAF D.XXI speed and climb.
A couple figures based on test flights, both took off weighting 1970 kg. Both datasets are took from graphs published in secondary sources, espesially that of FR-96 was a bit difficult, background being purely white and graphs being rather small.

First FR-107, which was one of maybe only 4 which got Mercury VIII during the war and test was flown when it was powered by Mercury VIII.

Climb to 5000 m 6'08", to 6000 m 7'53"
Max speed 352kmh at SL and 413kmh at 5000m.

FR-96, engine Mercury VII, max power 810-840 hp at 4420 m 2750rpm. Take off power at SL 728 hp at 2750rpm. On ground adjustable Ratier airscrew 3.0m diameter, reduction gear 0.666

Climb to 5000 m 7'12", to 6000 m 9'36"
Max speed 353kmh at SL and 416kmh at 4750m

Sources: Lentäjän näkökulma II
Ilmailu Joulukuu 1989
Suomen Ilmailuhistoriallinen Lehti 4/2000

First 2 for FR-96 and the latter for FR-107.

Juha

1. Reduction Gear on the 229 wreckage
2. Part of wooden wing on the wreck
3. 227 with in-between markings.
4. 1-V-2 LvR on Ypenburg shortly before the war (note the G.1 in the back)

During the first days of May 1940, several alarms were given. It became more clear that German was planning to attack The Netherlands. Therefore order 22B was issued on May 8th, which meant that every day between 03.15h and 8.00h, all a/c of the JaVA's and BomVA's should be ready to take off immediately. The other a/c should be spread outside the airfields in order to minimize damage during an eventual attack.
In the early morning of May 10th 1940, at around 01.20h, the time to be ready was changed to 03.00h. The JaVA were thus all ready when the German attack started.
The locations of the D.XXI fighters were:
1-II-1 LvR (1e JaVA) on De Kooij airfield (11 D.XXI's on readiness):
214
218
219
221
223
233
234
240
241
242
244

1-II-2 LvR (2e JaVA) (9 D.XXI on readiness):
213
224
225
229
235
236
238
239
245

1-V-2 LvR (8 D.XXI on readiness):
212
215
216
217
222
228
246
247

Not on readiness:
1-II-2 LvR (2e JaVA): 230, 232, 243 (all maintenance)
1-V-2 LvR: 227 (able to fly, but not "battle ready")
Flightschool, Texel: 226, 231
Fokker factory: 220 on repair, 90% completed
237 crashed on 11/22/1939 in thick mist near Hillegersberg, killing the pilot, and was scrapped

Hi Juha,

Thanks for the additonal data!

>First FR-107, which was one of maybe only 4 which got Mercury VIII during the war and test was flown when it was powered by Mercury VIII.

>Climb to 5000 m 6'08", to 6000 m 7'53"
>Max speed 352kmh at SL and 413kmh at 5000m.

I calculate to 5000 m in 6:17 min at 1970 kg, and to 6000 in 8:16. Good start

Is it clear from the graph if 5 km is the full throttle height? That figure does not match our previous assumptions ... maybe we're going to have to revise something.

Regards,

Henning (HoHun)

What seems odd to me is that the top spped of the D.XXI is about the same as that of the Gloster Gladiator, with an equevelent engine, ~250 kg greater take-off weight and being a biplane with almost 2x the wing area and a similar armament.

Inless the official operational performance figures for the Gladiator are significantly less than the commonly refrenced 414 km/h. (the Finnish wikipedia page gives 400 km/h at 4,200 m for the Gladiator Mk.II)

Hi Koolkitty,

>What seems odd to me is that the top spped of the D.XXI is about the same as that of the Closter Gladiator, with an equevelent engine, ~250 kg greater take-off weight and being a biplane with almost 2x the wing area and a similar armament.

Good point! For comparison, I believe the Ar 68E was about 100 km/h slower than the Me 109 with a roughly equivalent engine ...

Regards,

Henning (HoHun)

Juha, wat are your figures for the Gladiator's performance?

Very impressive collection of informations to an barely well discussed topic. Wonderful as always, Marcel!

Hello HoHun
the speed graph is very "flat" along x ie speed axis and it is difficult to say for sure the exact altitude of max speed but it is appr 5 500 m.
From Gladiator info the max power, for 5 min, for Mercury VIIIA 810-840 hp at 4270 m (14 000ft), so the altitude is same as that Marcel gave.

KK
Finns were not very interested to test Gladiator Mk. II thoroughly, but for a new plane
330 kmh at SL and 400 kmh at circa 4500m.

Source for Gladiator Lentäjän näkökulma

Juha

I just realized you listed the Mk.II specifically. Was the Mk.I Gladiator tested more thoroughly?

Hello KK
FAF had only Mk. IIs, which arrived in Jan-Feb 40, in the middle of the Winter War. They were given to LLv 26 as soon as possible because the designed a/c of the LLv 26, Fiat G.50s, were delayed badly because Germany's refusal of transit. Gladiator was not interesting a/c for FAF as an example of a/c design, so it wasn't thoroughly tested after the Winter War.

The air unit of Swedish volunteers during the Winter War, F 19, had some 6 - 9 Gladiator Mk Is but they were even less interesting a/c to FAF in testing sense.

Juha

Meanwhile, continuing the thread, we've arrived at the night of 9 to 10 May 1940.

To give you an insight in the situation at the start of the hostilities:

On May 9th 1940, the German Luftwaffe was fully prepared for the assault on the west, which could not be recalled after 19.10h. The total force of a/c unleashed against the Dutch consisted of:
430 transport a/c
389 fighters
261 bombers
52 mine laying a/c
94 reconnaissance a/c
6 light a/c

A total of about 1200 planes. (I have a list of units, but found it too long to type for this thread)

Against this, the Dutch could put the already mentioned 29 active D.XXI's, 23 G.1's, 9 T.V bombers, 11 Douglas 8A 3N attack planes, 7 D.XVII's (fighter), 61 C.V's (rec), 15 C.X (rec/bomb) and 16 FK51's, a total of 171 a/c of which 99 were obsolete bi-planes.

At 20.30h May 9th 1940, Dutch AA gunners spotted a reconnaissance a/c over Dordrecht. This is confirmed by British radar logs. At 23.30h, Ruigenhoek airfield reported many a/c flying west. After this many reports of a massive neutrality violation of a/c flying west came from all over the country. At 02.00h, Schiphol airport went into the highest alert phase. At 03.00h all Dutch fighters were on readiness.
At 03.30h German Mine laying a/c started to drop the first mines in Dutch waters. A Dutch warship, the Johan Maurits shot one down, the first of German a/c to be shot down over The Netherlands.
Meanwhile the German main bomberforce turned over the Northsea, to fly east again, to the Dutch coast. At 3.30h, German a/c attacked the airfield Waalhaven in Rotterdam. The real attack started at 03.45h.

Unit was ready at 03.00h. After hearing many a/c flying over, the commander, capt. Schmidt-Crans, asked his superiors for permission to send out a patrole. He didn't get it.
While talking to the command post on the phone, he heard another voice in the background talking about bombing. This was enough for him to give the order on his own and at 03.59h, the whole JaVA was airborn, in time to avoid being wiped out on the ground.
The JaVA was divided into 4 patrols of 2 to 3 D.XXI's, patrolling the North part of Holland.
No 244 (Wmr Hatebroek) attacked J88 5J+?T from 9./KG4, forcing it to land on the beach. (this Ju 88 was recaptured and repaired by the Germans after the capitulation). 234 landed on Schiphol and flew back to De Kooij, landing there at 07.00h.

Between 4.30h and 4.45h, no. 214, 221, 223, 233, 234, 240 and 242 landed and refuelled. The remaining 3 (218, 219 and 241) were just landing, when they were attacked by 9 Bf109E's from 4./JG186. 241 (Lt. Bosch) was destroyed while landing. The pilot could get out safely. 219 (Lt. Overvest) could just pull up, while 218 (Lt. Focquin de Grave) could take off again. All flying D.XXI's were called back to base and there was a dogfight between 8 D.XXI's and 9 Bf109's, lasting about 10 minutes. 3 Bf109E's were shot down (by 234, Lt. Van der Stock; 221, Lt. Doppenberg; 219, Lt. Overvest) against none of the D.XXI's, although all D.XXI's were more-or-less damaged. One of the Bf109E's (Hptm Robitzsch), shot down by 219 crash-landed on De Kooij, the pilot was taken prisoner and later shipped to the UK. Uffz. Rudolf (shot down by 221) died of his wounds after crashing near Anna Powlona and the 3rd Bf109 crashed in the sea, fate of the pilot unknown.

223 (Wmr Zuijlen) did not take part in the dogfight, not being warned because lack of radio. He attacked 2 Heinkels near Katwijk, and was probably killed in that fight. His D.XXI didn't crash, but flew on for some time, right through some German formation, finally crashing near Wassenaar.

At 05.30h, 4 D.XXI were ready again.

06.15-07.10, Patrol 234 and 240
08.00, all D.XXI were damaged in an airraid 214 and 233 beyond repair
12.00h 4 D.XXI trying to start, 234 (Lt. van der Stock was shot on fire by raiding Bf109's (Van Der Stock survived and got his fame when he was 1 of 3 pilots escaping from Stalag luft III in the great escape)
Only 6 D.XXI's were still in tact and at 19315h, 218 and 244 l;eft for the secret airfield Buiksloot.
221, 240 and 242 would do the same the next day, while 219 would leave on May 12th.

Photo's:
1. Bf109E-4 'Schwarze 1' (Hptm Robitszch) after crash-landing on De Kooij
2. Wreck of 223 (Wmr. van Zuijlen) near Wassenaar
3. Grave of Wmr Van Zuijlen
4. Burning 234 (Lt. Van der Stock), picture taken by pilot imediately after the attack.
4. Wreck of 241 with Lt. Bosch in front of it

Lt. van der Stock describes the dogfight of 1e JaVA quite different. He claimes 12 D.XXI's fought 16 Bf109's. He also claims that his plane 234 was burned while landing, not while making ready to start. I thought his story was quite inaccurate (for instance, 1e JaVA never had more than 11 a/c), so I left it out.

2e JaVA took off from Schiphol airport between 03.45h and 04.00h, in the midst of a German attack. As the radiopost was damaged during the attack, no communication was possible and every pilot had to take care of himself.
229: Lt. Sluijter shot down Ju88 5J+GT (Oblt Rinck, 9./KG4) over Schiphol and later landed on the secret airfield Ruigenhoek at 04.15h. At Ruigenhoek, people were very surprised as they were not aware that the war had started.
236: Sgt De Geus, damaged an unknown Ju88. Landed at Ruigenhoek at 04.30h with empty MG's.
225: Sgt Looijen landed on Ruigenhoek.
245 Sgt Bulten, landed at Schiphol while being wounded.
213(Sgt Burger), 224 (Lt Sitterd), 238 (Lt. Bodaan), 239 (Sgt Roos) and 235 (Lt Plesman) landed at Schiphol between 04.18h and 04.45h.
213 and 239 were sent to Ruigenhoek where they joined the 3 D.XXI's which were already present. They formed a patrol, flying to Gouda where a Ju52 was shot down. Lt Sluijter was wounded in that action. Two other Ju52's were forced to land. Sgt. Looijen (225) was shot down and killed by Bf109E (7./JG 3) (Uffz. Massman) near Oudekerk a/d IJssel. While going back, some German a/c on the beach were raided.
A KLM pilot, Res. Sgt Steensma, reported for duty and was assigned to fly the 239. (Story). At 12.00h, 238, 213, 235, 224, 236 and 239 escorted 3 T.V's to attack Waalhaven (in German hands). Lt. Bodaan (238 ) was shot down and killed by Bf109E (Uffz. Springer, 7./JG 3). 236 shot down a Bf109E (III/Jg 3). 239 probably shot down another Bf109, but 239 was so heavily damaged at had to be abandoned after landing on Schiphol. Later in the afternoon, the remaining D.XXI's were ordered to Buiksloot in order to reform a new JaVA together with the remainders of 1-II-1 LvR (1e JaVA).

Thanks Marcel!
Very interesting!

KK
One point to D.XXI vs Gladiator, FR-167, the Wasp powered D.XXI with retractile undercarriage, was 15-37 kmh faster than normal Wasp powered D.XXI depending altitude.

Juha

The unit was ready at 03.00h. When the observation post at Delft reports approaching bombers at 04.00h, the D.XXI's take off. They are aided by the fact that there's no wind, so they could take off from standing position in any direction.
1-V-2 LvR is divided into 3 sections:
1. Lt. P.J.B. Ruijs de Peres (222), Sgt. G.K.P.Kiel (216), Sgt. J.Eden (247)
2. Lt. G.Steen (246), Lt. A.M.van de Vaart (212), Sgt. J.Linzel (215)
3. Lt. F.G.B.Droste (228 ), Sgt. P.J.Aarts (217)

The D.XXI's immediately got themselves into a fight with Bf110's.
222 (Ruijs de Peres) MG's were jammed, thus could not participate. Ruijs de Peres however stayed in the air until being wounded and having to make an emergency landing near monster.
216 together with 247 attacked a formation of Ju52 (with Falschirm jaeger) and shot one down. Later landed on Ruigenhoek. There, he re-armed and refuelled. After taking off, the D.XXI was attacked by 5 Bf110, after which it crashed, uside down near Den Deijl, in the midst of German paratroopers. After playing dead for a considerable time, sgt. Kiel could reach Dutch units and was brought to a hospital, wounded.
247 Shot down a Bf110 and landed at Ypenburg again at 05.00h. While landing, 247 was shot to fire. Sgt. Eden jumped out and tried the 227 which was not battle ready. 227 was shot to pieces as well before it could take off and Eden joined the ground fight against German paratroopers at the airfield.
246 had jammed MG's as well, landed together with 215 (Sgt. Linzel) and changed pilots. (story) Groundcrew only had to put the airpressure on for the MG's to function. Linzel with 246 shot down a Bf110 (Schroder? 6.ZG1) (maybe only damaged), but was wounded a little later and had to bail out. Pilot wouded and brought to the hospital.
215 After changing places with Sgt. Linzel, Lt Steen fought with several German a/c after which he crash-landed on the beach. 215 was set on fire by German planes by a Dutch torpedo boat.
212 Shot down a Do17 near Amsterdam. Then made an emergency landing at Schiphol, without engine power.
228 Shot down an unknown Ju88, landed at Ockenburg around 05.00h.
217 Shot down an unknown Bf110, landed at Ockenburg around 05.00h.

212 was re-assigned to the combined JaVA at Buiksloot.

1-V-2 was virtually non-existent after 05.00h. Lt Steen, Lt Droste and Sgt Ottes (227) were re-assigned to Schiphol, to fly G.1's.
Ypenburg was captured by German Fallschirm Jaeger. Later it was re-captured by Dutch troops, but was not usable. The same happened to Ockenburg. 217 and 228 could not fly from there again and were captured in tack by German troops after the capitulation, May 14th.

1. 288 at Ockenburg
2. 215 on the beach.

Many sources claim:

These aircraft's most important victory took place at dawn on May 10, 1940. . . . . . they succeeded in shooting down 38 . . . . Ju 52's out of a group of 55 that was crossing the Dutch border.

Click to expand...

This has been quoted on this forum on a number of occasions as well. As we saw, there's no record of this battle, thus is untrue. Where this rumour comes from is unclear to me.

For a better picture, here a map with the locations of all mentioned airfields:

In the evening of May 10th, the Dutch structure of 3 D.XXI units was abandoned and a new combined JaVA was formed on the secret airfield Buiksloot, a former glider field.
At first it had only 8 D.XXI's on strength: 212, 213, 218, 224, 225, 235, 236 en 244. In the morning om May 11th, 3 more a/c arrived from De Kooij: 221, 240 an 242. In the morning of May 11th, personel from 1-II-1 LvR arrived and the commander of that unit now commanded the combined JaVA. In the evening, the unit was strengthened with 4 D.XVII's from the flightschool at Texel. Why the there present D.XXI's, 226 and 231, were not used is unknown to me.
Missions:
06.45h , 218 and 224 escorted C.V 592 to the Arnhem region. 592 had to turn back at Rhenen because of engine trouble. The aircraft returned at 07.44h

10.10h 212, 235 and 240 escorted the C.V's 619 and 645 to Arnhem and back, landing at 10.45

13.09h, 213, 229 and 242 escorted 2 T.V's (850 and 856) in an attack on the bridges in Rotterdam. 850 was shot down after the bombing. The formation was attacked by 12 Bf110's. 213 (Foquin de Grave) was attacked by 6 Bf110's, shot down 1 of them and probably damaged another after which he was wounded and made an emergency landing. The a/c was later set on fire by Dutch soldiers.
229 was attacked by 3 Bf110's. Sgt. Roos eliminated one by jettisoning his canopy, which struck the Bf110 in the propeller. He then shot down another one, after which he was thrown out of his fighter. 229's wreck is on display at the Crash '39-'40 museum. (Story)
242 and 856 made it safely back to base.

15.55h Patrol by 235 (Van der Stock) and 240 (Bosch).