Bald Eagle Aviation

b29flteng · **Posted:** Wed Jul 04, 2012 12:10 pm

The radiator on the 51 actually puts out approximately 150 lbs. of thrust which overcomes the drag (Meredith effect). Not so on the Spit. The Griffon engine puts out about 2,200(?) hp. vs. 1,400(?) for the Merlin. With the two flying side-by-side, it demonstrates how much less drag the 51 has vs. the Spit when the 51 uses about 1/3 less horsepower.

51fixer · **Posted:** Wed Jul 04, 2012 4:34 pm

To get the max thrust out of it you need to run the coolant temp on the high side of range.
We run ours cooler around 102-5 degrees C.
You lose the thrust benefit percentage wise by having the door open a bit more. The door is the thermostat for the coolant system primarily. You have an adjustment screw on the actuator which allows you to fine tune the temp you run the system at.
If you do the low level aerobatics with a good deal of speed changes you can keep temps from spiking too high by running the temp setting lower. We typically adjust the setting a few degrees warmer in the fall and dial it cooler in the summer. You access it through the hellhole panel on the bottom of the fus aft of the coolant door. Its a pain to get to.
It was a very advanced technology and was built by Robertshaw Co.
Does the Spit have something similar to maintain coolant temps- NO. This Spit has air operated rams for the Coolant outlet doors. It is fully closed or fully open. A temp probe will open it if it gets above a set temp or you can manually open them. No thermostat system is presently installed. They originally had a mechanical thermostat but malfunctions happened so the systems were removed. The system runs pretty cool and is pretty efficient. So much so it is hard to keep it warm enough in the winter months.
They actually had ducting in the wings of Spitfires to grab hot air from the exhaust of the radiators and used it to keep weapons and cameras warm.

So while the P-51 design does develop thrust the present day low altitude use reduces the effect of it. It is still a more efficient and streamlined system than on the Spitfire.

b29flteng · **Posted:** Wed Jul 04, 2012 5:17 pm

Just a side note, the P-51B/C is a bit faster than the P-51D using the same power settings.

Django · **Posted:** Fri Jul 06, 2012 10:48 am

Neat to compare the two like that. Thanks!

RHenry · **Posted:** Fri Jul 06, 2012 11:08 am

With all the attention to detail in this fantastic thread, I'm surprised no one mentioned the prop change on Bald Eagle?!?

51fixer · **Posted:** Thu Jul 12, 2012 10:52 am

Got an item on epay the other day. The Dzus tool in BE wandered off so I got this one that my son found listed under Spark Plug Gap Tool.

Neatly engraved with the NAA logo and name on both sides.
There was also a Snoopy type with Air Corps embossed on the handle but my bid wasn't high enough for that one.

I have been working on getting the flight controls from SNJ-3 #22 ready for covering. One thing that had never been done was to install the tail nav light on the rudder trailing edge. It had a football type wingtip housing attached to the top of the rudder.
Directions from the North American Aviation instructions to change the SNJ/T-6 to civil use are dated Oct 1945 and only go up to SNJ-4, T-6C. It mentions in it that Flight Tests had yet to be done on later Aileron Control system as installed on the later models, SNJ-5/ T-6D and later. This would refer to the High Roll Aileron system.

Diagram and instructions to install the tail Nav light on the rudder trailing edge.

Some of the work to do this-

The light mount came from Lance and is a Grimes product-

The fairing I have cheated on and they are from a Money M-20 series stinger.

51fixer · **Posted:** Thu Jul 12, 2012 7:08 pm

Tail Light Progress-

51fixer · **Posted:** Tue Jul 17, 2012 1:02 pm

The prop has arrived from O/H-

We will need to add stencils and stripes-

So it will look like this photo of this A/C-

I'm thinking Red,Yellow,Black.

Old Shep · **Joined:** Thu Jun 09, 2005 5:49 pm **Posts:** 219

Hi Rich:

Really enjoy your posts....I think the prop tips on the -3 Jaybirds are blue, red, yellow and not black.

Old Shep

51fixer · **Posted:** Tue Jul 17, 2012 2:20 pm

Old Shep wrote:

Hi Rich:

Really enjoy your posts....I think the prop tips on the -3 Jaybirds are blue, red, yellow and not black.

Old Shep

Anyone have a color photo?
If blue is it insignia blue?

Old Shep · **Joined:** Thu Jun 09, 2005 5:49 pm **Posts:** 219

It is insignia blue. Can't remember where I found the documentation...mine is painted with insignia red, insignia blue, and chrome yellow.

bdk · **Joined:** Sun May 02, 2004 1:16 am **Posts:** 11324

Could it be documented in the Air Force paint spec?

51fixer · **Posted:** Wed Jul 18, 2012 3:23 pm

bdk wrote:

Could it be documented in the Air Force paint spec?

I haven't found any info in regards to prop painting.
The wing print calls out yellow from attach angle to inboard aileron and this one has pics showing yellow from attach angle to wing tip with what looks like a red stripe.
Will keep looking.

51fixer · **Posted:** Wed Jul 18, 2012 4:50 pm

I'm doing some work on the P-51 but thought I would update the rudder-

N3Njeff · **Posted:** Thu Jul 19, 2012 5:55 pm

51fixer wrote:

bdk wrote:

Could it be documented in the Air Force paint spec?

I haven't found any info in regards to prop painting.
The wing print calls out yellow from attach angle to inboard aileron and this one has pics showing yellow from attach angle to wing tip with what looks like a red stripe.
Will keep looking.

Hey Rich,
I have a copy of the USN painting specs for that era. Dark Blue and the bands are a specific width, let me dig it out and try and scan for a copy.

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