American version of events

Mission Summary Report                15 July 1944

A. 56th Fighter Group, Col. Zemke leading

B. 48 P47’s. (Time up 1727 hours. Time down 2140 hours (6 Beach Head)

C. Two, one as escort

D. F.O. 449 Bombing and strafing.

E. One.

F. One, catagory « A » and one catagory « AC » Flak.

G. 1 NYR, Lt. R. E. Jenkins, 63rd sqdn. Bailed out 2-WL-1686 (Lat 47,56827° Long 1,22087)

H. 5 plus passenger and 11 plus freight cars damaged, 63rd Sqdn. 

      9 Trucks damaged, 62nd Sqdn.

I. Arrived Blois 1850 hours, 14000ft. Briefed area 10/10 overcast and two T/O’s chosen. La Chapelle A/D 2-WL-1796 (Lat 47,65833 Long 1,23229) and Vendome M/Y 2-WF-0513 (Lat 47,80958 Long 1,06891).


One Sqdn. Bombed each and Vendome also strafed. Nine trucks damaged between 2-WF-1898 (Lat 47,67644 Long 1,24523) and 2-WF-0513 (Lat 47,80958 Long 1,06891). NYR thought due to XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX engine failure. Balance report same as telephone.


Flak:   3/4 Hy guns N woods 4-VL-0588, moderate inaccurate.

  4 mile radius 4-VR-2397, intense accurate by. XX Hy. 11/12,000 Ft.

  4 gun Hy battery 4-VR-2796.

  4-VL-9428, intense accurate. Hy 8,000 ft.

The line of X's is a phrase that has been crossed out. I spent some time using various tools and eventually understood that the line crossed out says:

Flak:   3/4 Hy guns N woods 4-VL-0588.

This line is repeated a sentence later so I believe the clerk typing the report was reading a hand written statement and jumped a line before realising the mistake. Rather than re-writing the whole page, the line was just crossed out before continuing. 

Two other aircraft have been damaged by flak. One is category 'A', it can be repaired on site, the other is category 'AC' meaning its repair is beyond the capabilities of the on-site repair team. It appears that 6 of the Thunderbolts landed at the beach head in Normandy. The remainder landed at Boxted at 9:40 pm.

Notes:

The map co-ordinates like 2-WL-1686 use the French Lambert system. The flak co-ordinates further to the north starting with 4- use the 'Nord de guerre' system. Both are readily converted into latitude and longitude using this tool: Echodelta.net  The flak data is helpful as it allows us to work out the route taken.

NYR is 'Not yet returned'

Hy is 'Heavy'

A/D is aerodrome

Many thanks to Boxted airfield museum for this mission summary

63  Squadron Mission summary

Bombing and strafing. Arriving in the vicinity of Blois at 1900, we proceeded to the aerodrome of La Chapelle (Le Breuil), where we dropped 28 x 250lb (115 kg) bombs with excellent results. Two dispersal areas were destroyed and one hanger damaged. Four of our bombs had to be jetissoned 12 miles E of Clacton in the North Sea.

Up 1730, Down 2135

White: Maj Goodfleisch, Jenkins, Becker, Stewart

Red: Casteel, Ferber, Kling, Magel

Blue: Hall, Frye, Curtis, Warboys

Yellow: Wakefield, Timony, Caldarone, Flagg

Many thanks to Patrick  Frigerio for this mission summary

Eyewitness account by Marvin H. Becker 63rd

2nd Lt Robert E. Jenkins   Missing near La Chapelle A/D, Fr. 15/7/44

“Lt. Jenkins was flying number two position in Daily White flight and I was number three. Our leader picked out an airfield (La Chapelle) as a target and Daily squadron proceeded to dive-bomb it. As Lt. Jenkins pulled up ahead of me, at about 8000 feet, to lose speed before diving, I noticed light smoke being emitted from his supercharger exhaust and I assumed that this was a result of cutting his throttle.

In my dive I was concentrating on my own bombing and did not notice Lt. Jenkins again until he pulled out of his dive slightly lower than I did, at about 2000 feet. As he pulled out, there was a long trail of dense gray smoke coming from his supercharger exhaust. The smoke kept coming out as he flew level at about 2000 to 2500 feet. At intervals the supercharger exhaust would belch flame, and the engine appeared to be running rough as the smoke and flames were at times ejected in puffs.

I then called Lt Jenkins and asked him what his trouble is, He replied.  "I don't know. My carburettor air temperature is 150 (°F)". Someone then told him to check his intercooler doors. Major Goodfleisch told him to start home with someone as escort.   I called Lt. Jenkins, saying that I would go with him. His engine must have been losing power, as his next transmission was, “I’m at 1500 feet and will have to bail out”. A few seconds later, as I watched for Lt. Jenkins' parachute, I saw the plane nose down to 60 or 70 degree angle, as if it were trimmed nose-heavy and the stick released. The airplane crashed and exploded in the woods just west of Blois.  It was trailing flame as it went in.

I did not see Lt. Jenkins or his parachute. I was about 1500 to 2000 feet above him as he made his last transmission. Several other men in Daily squadron were looking for the parachute as well, but failed to see it”. 

Signed by 1st Lt. Marvin H. Becker.


The flight path from Marvin Becker's statement

Marvin Becker's photo and many others are available on this site: www.56thfightergroup.co.uk/63pilots/abbotts-dale/index.html  He was promoted to 1st Lieutenant on the 7th of July 1944 and survived the war. He died in 1999 in Florida.

Eyewitness account by William Heaton 61st

On 15th July 1944, I was flying Whippet Yellow three on a mission to France. At about 19:20 I heard a radio call from Daily White Two saying in substance that his carburetor air temperature was 150° plus and that he was heading down the river headed out. Someone told him to open his intercooler doors and he replied that they were open. After about one or two minutes he called that he was down to 1500 feet  and was getting out. A call to him was next answered by another plane saying he was already out. When Daily White two said he was getting out, I looked down at the two planes below me. Just south of where he crashed 2WL1686, I saw a chute open on the tree tops.

William M. Heaton, 2nd Lt., Air corps. 


Note: The phrase I've highlighted is at odds with what Marvin Becker says. Becker has the route as Le Breuil south to Molineuf. Heaton says he followed the river to Molineuf ie East to West.

Whippet is group A in 61st squadron. The mission summary doesn't mention 61st squadron being involved in the mission. The co-ordinates are the same as those given in the mission summary.

Photo of William Heaton from 56thfightergroup.co.uk 

Missing Air Crew Report 6715

Useful information from this document:

Last sighting 15 July 1944 at 19:20 hours.

Aircraft lost due to: (not known) Believed to be engine failure.

Aircraft P47D20 sérial42-76878, Engine R2800-59 serial FR000612

Installed weapons (Left and right):

1L 11074802, 2L 1097988, 3L 1097150, 4L 1016811 

1R 1084833, 2R 1113759, 3R 1098345, 4R 1098535 (4L Colt, others high standard). 

These are 8 Browning M2 0.50' calibre machine guns manufactured by Colt or High Standard. 

Person missing listed as a battle casualty.

Witnesses:

Becker Marvin H 1st Lt O-310458 by radio

Heaton William M. 2nd Lt O-814686 by sight

Parachute was used: Yes

Date of report 16 July 1944 Nathan S. Neu. 1st Lt AC assist adjuntant

The MACR 6707 is a photocopy of this report but has slightly different hand-written annotations.

From: National archives catalogue number: 305256, NARA group 92, Roll 02401-02500

What might have gone wrong?

Pilot died

Why?

Aeroplane crashed in forest at high speed

Why?

Engine didn't provide enough power for the aircraft to stay airborne

Why?

Fuel evaporated inside carburettor, detonation at wrong part of engine cycle

Why?

Air intake temperature much too hot

Why?

Intercooler didn't cool the air going to the carburettor

Why?

Intercooler failure

Turbo-supercharger diagram found here: www.aircorpsaviation.com/december-january-dakota-territory-air-museum-p-47-update-2/ 


The intercooler and turbo-supercharger

The intercooler on the P47 is a large radiator situated behind the pilot and in front of the turbo-compressor. The air intake is beneath the engine, air is ducted back to the turbocharger where it's compressed but very hot so it then goes through the intercooler to reduce the temperature and increase the air density. From there it's piped forwards to the carburetor and the via the inlet valves, into each of the combustion cylinders. The exhaust gases return to the lower part of the turbo-compressor to spin it at high speed (18000 RPM) and finally the spent gases leave the aircraft via the flight hood situated just in front of the tail-wheel.

If the intercooler were to fail, the air reaching the carburetor would be too hot for correct combustion. The fuel would detonate on contact with the hot air rather than due to the spark from the two spark plugs in each cylinder. The result would be a loss of performance and perhaps engine damage. Normal air temperature was 12 to 35°C (54 to 95F) and it should never exceed 45°C (113F) in normal flight. Jenkins radio message said his was 150F (65°C) ie. right up against the needle stop.

Photo from P47N flight manual 

The intercooler itself is cooled by air ducted across it. The cooling air leaves the aircraft by the intercooler exit doors located on the side of the rear fuselage. The pilot could control the doors and would want to keep them closed when there is a risk of carburetor icing. One of Lt Jenkins collegues refered to these doors in a radio message.

Image taken from the T.O. EX 00000 manual shown on this site: www.aircorpsaviation.com 

Author's analysis of the American version of events

The mission summary says that 63rd squadron hit '5 plus passenger and 11 plus freight cars damaged' it doesn't mention any damage done to the arfield. Marvin Becker however states that 63rd squadron dive bombed the airfield at Le Breuil. 63rd squadron therefore seem to have hit multiple targets, not just the airfield. Becker goes on to say Lt Jenkins had a visible problem when he cut the power and gained height to lose speed before his dive towards the target. The problem became much more apparent when he put the power back on to come out of the dive. The aircraft only rose to 2500 feet before leveling out so was already down on power.  

The distance from the airfield to the crash site is 7 miles, this would have taken 1 minute and 22 seconds at 300mph. During this short time Lt Jenkins tried to work through the problem to save the aircraft. When it became clear this was an impossible task he decided to bail out but was only at 1500 feet (the lowest safe height to bail out was 1000 feet). The aircraft went into a rapid descent. Going from 1500 feet to 1000 feet at 300mph and a 65° slope would have taken just over a second. If the speed had by then reduced to 200mph then it would have taken less than 3 seconds. In either case, the time to take his hands off the stick, undo the harness, radio lead, oxygen connection and open the canopy was extremely short, he would also have been trying to push the canopy uphill (as the aircraft was nose down).

The original problem, overheated air going to the carburetor due to a problem with the intercooler is unexplained. The intercooler has two cooling ducts and two exit doors, a simple system. It's difficult to imagine a fault which would be common to the whole cooling system. Also, an intercooler failure does not easily explain why the aircraft caught fire.

Marvin Becker's statement is clear that Robert Jenkins didn't bail out but the mission summary, the MACR, Heaton's statement and what McMahan had heard, say he did. Sadly for Robert's family, this confusion was to continue.

Becker estimates the final nose-dive towards the ground at 60-70°. The last radio message was at 1500 feet, just 500 feet above the safe bail-out height. Taking 65° as the dive angle, the distance travelled is 551 feet, which at 300 mph would take a second. (or a little over two seconds at 200 mph).