F-51D s/n 44-63528 with two XRJ-30-MA Ramjets ...

[Mark Allen M]

... which crashed in 1948.



A bit of the accident report below.

Link here: http://www.fightercontrol.co.uk/forum/v ... 94&t=78756

Place of Accident - Ohio, Montgomery, Dayton 8 miles North
Nearest Airfield - Wright Field
Date - 19th August 1948
Plane Serial - 44-63528
Plane Type - F-51D
Date of Manufacture - 20th November 1944
Total flying Hours - 341.15
Last Overhaul - New
Operator - 1st Lieutenant Paul L. Chell of the USAF
Unit - Flight Test - Fighter Operations Section
Flying Experience of Operator 1641.4 hours total, 286.4 hours on this type, 61.05 hours on this plane, with 125.4 hours in the last 90 days

Special equipment carried on plane:

'This particular F-51D was equipped with one ramjet engine on each wing tip. Each jet used fuel only from left and right wing tanks respectively. The electrical equipment for each engine (Boost pump, solenoid shut off etc) was located immediatety outboard of the wing tanks, behind the gun ports. Since the fire started in this section it is believed that a combination of an electrical spark and leaking fuel was the exact cause of the accident'

Ramjet Performance:

The ramjet was build by a company called Marquardts and was a subsonic design of 20 inch diameter.

The F-51D obtained a speed increase of 40 mph (approx 9%) when in use, increasing top speed from 437 to 480 mph. Whilst not much, it must be remembered that the ramjet weighed only 100 lbs and produced 10 times its own thrust, i.e. 1,000 lbs of thrust

Pilots statement:

'Takeoff was approximately 1430 on the 19th August 1948. Takeoff was normal. Tests were being run as prescribed by the project engineer. After approx 15 minutes of normal Jet operation, the right jet flamed out. A normal restart was made. After one of two minutes of operation, the right jet flamed out again. Just as another restart was being made, a severe explosion was heard. The explosion occured inboard of the ramjet and either on the bottom or inside the wing. Lateral control was nearly impossible and almost immediately flames were observed inside the wing about a foot or two from the wing root. Fuel was turned off, power reduced, and the airplane was brought to a stall attitude. The canopy was then released and egress made from an inverted position.

Paul L. Chell, 1st Lt, USAF'

The plane crashed into a wooded area burning brush for about 100 foot radius, and here are the photos from the crash report.

[JohnB]

That will buff out...

If that was a Spitfire or Mustang in Europe, it would already be flying again...as long as the dataplate survived.

[Lon Moer]

I'm not so sure about this one....

[seagull61785]

I wonder what the handling would be like when one of the ramjets stopped working.

The asymmetric thrust would be very interesting to say the least.

Would it make the aircraft spin around like a pinwheel firework?

Hanging out on the wing tips like that the arm/turning force moment would be incredible if only one were producing thrust.

Anyone got any ideas?

Barry

[bdk]

I wonder what the handling would be like when one of the ramjets stopped working.

The asymmetric thrust would be very interesting to say the least.

Would it make the aircraft spin around like a pinwheel firework?

Hanging out on the wing tips like that the arm/turning force moment would be incredible if only one were producing thrust.

Anyone got any ideas?

Barry

At 480 MPH, probably not much. The pilot was restarting for the third time after all. The vertical stabilizer is also at a similar moment arm.

[seagull61785]

Thanks - I didn't spend enough time thinking it through.

One more question - Would rudder deflection provide a similar force to a ramjet?, - given the similar moment arm.

[bdk]

One more question - Would rudder deflection provide a similar force to a ramjet?, - given the similar moment arm.

I think at those speeds the rudder would take a lot of force to deflect significantly. The vertical stabilizer probably does most of the work anyhow keeping the aircraft from skidding sideways.

I think the airplane had to go pretty fast to even light the ramjets and I doubt they came on line at the same instant or were very throttle-able.

[Lon Moer]

In late 1945, a P-51D was modified with two Ford PJ-31-1 pulsejets. This engine was a near-copy of the Argus model used on Germany’s V-1 buzz bomb, and intended for the Loon missile. The problem with this set-up was the same as with every mixed-propulsion fighter ever tried; in that when the jets were shut off, they were just dead weight for the plane to lug around. The modified Mustang was grossly uncompetitive on it’s piston engine alone.

The idea itself was not as far-fetched as might be assumed today. In late 1945 the US Army had thousands of existing WWII-built Mustangs already paid for, and a speed boost would keep them competitive in the homeland defense role for years to come. The PJ-31-1 engine was incredibly simple, easy to maintain, and could be built dirt-cheap.

The cancellation of the remainder of the Loon contract would have greatly pushed up the price of each Ford pulsejet. Because of this and the inherent performance limitations of the scheme itself, the idea was dropped in 1946.

[JohnB]

The photo of the Mustang flying is the one you always see when this topic is mentioned. It's even the photo used in the 1955 Ground Observers Corps recognition manual for the Mustang.
The serial isn't visible, but there is a difference in the national insignia....no bars.

Same aircraft?

[Lon Moer]

The photo of the Mustang flying is the one you always see when this topic is mentioned. It's even the photo used in the 1955 Ground Observers Corps recognition manual for the Mustang.
The serial isn't visible, but there is a difference in the national insignia....no bars.

Same aircraft?

That was why I posted "I'm not so sure about this one.".
- the visible part of the serial number 'could' be the ___28 of the known aircraft, but no bars in the insignia....?
- the ramjets themselves look right, but the exhaust/flames exiting them is......??

[JohnB]

The very fact the photo appears in the GOC recognition manual indicates it's a USAF photo and dates it to the correct period.

[Mark Allen M]

I'd say two different Mustangs? ...