British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

[dunmunro]

According to Porteous Mk6 and GRUS/GRUDOU and/or Flyplane was superior to Mk37.

Interested readers might wish to access the on-line (Navweaps) copy of the document "From Fellside to Flyplane" by Roger Porteous and read for themselves what was written; see Chapter 10 - "Sea Trials in HMS Broadsword" (pg 49). These initial sea trials of Flyplane took place in 1949 - 13 years AFTER development of the Mk37 GFCS had been commenced and 10 years AFTER Mk37 series production had commenced.

If anyone can identify the passage where Mr Porteous (either Iville or Roger) stated that "Mk6" or "GRUS+GRUDOU" was superior to Mk37, please let me know; I cannot seem to locate it.

Meanwhile, for reference -

> The first prototype GRUDOU (Gyro Rate Unit Deflection Oil Unit) was tested at Frazer Battery at the end of 1942 or early 1943. After a successful series of tests, GRUDOU was approved for production and fitting to all RN warships already fitted with HACS+GRU; this production and installation effort was finally completed by the end of 1944.

> The first prototype GRUS (Gyro Rate Unit Stabilizer) was not fitted to a RN warship (HMS Implacable) for testing until 24 Sep 1944; the test was successful and a production order for 25 units was consequently issued. The GRUS+GRUDOU combo did see action in the PTO aboard HMS Implacable, but it is quite uncertain whether any other British carriers in the Pacific were fitted with GRUS (see Admiral Vian's report; "From Fellside to Flyplane", page 39).

> Per "Naval Weapons of World War Two" by NJM Campbell (pp 18-19), the latest model Mk VI director with the latest Type 275 radar and the latest NRS (Naval Reflector Sight) Mk 2G was found to have unexpected problems. According to Campbell - "The original NRS (Naval Reflector Sight) Mk 2G, known in a later version as Gyro Deflection Sight (GDS Mk 1), was intended to put nearly all trajectories through the VT fuze circle up to at least 4000yd but trials in 1944-45 indicated that the limit was about half the above. The Simple Electric Deflection Calculator (SEDC) could provide a measure of tachymetric computation to 4000-5000yd and GRU to about 3000yd but the former was not immediately available and GRU had to be fitted below the director."


Byron

Maybe you have a different copy than me:

On page 51: 'Our Guns Stagger American Chiefs'....The guns succeeded in hitting high speed targets that United States gunners had never been able to get near...

and

Later Axbey told IP of a meeting in 1953 with Eric James 'an electrician in charge on HMS
Broadsword while on gun trials in America'. (James had joined Ferranti after leaving the
Service.) James told Axbey that '24 rocket targets were sent over the American guns - they
missed every one- and then on over the Broadsword's guns and they accounted for 23 out of
the 24. The one was out of range'. 132

[Steve Crandell]

We have no way of knowing how many of the kills by 40mm and 20mm were seriously damaged by 5" fire before they got within range of the former, but the CIWS would always get credit for the kill.

[wmh829386]

We know in practice, automatic mode in Mk37 is faster than rate control. We even have test data on its the probabilities for TTB in automaic mode using VT ammo. You are exaggerating to say that manuvers always defeat the FC solution of by Mk37. With gun crew with good dead time discipline, we can scale the kill probability of the test results.

OK, please do.

Let's do a rough estimate by using fuse time error of 0.15s and dead time error of 0.5s. Take the plane speed of 140knots=238 ft per second.

Assumptions: In the test, TTB are determined by burst within 100ft of the target, with over 95% within 80ft. If we replace VT fuse with MT fuse, for all the projectiles that could be triggered, only a fraction will burst within the radius.
In a simplified geometry, the MT fuse need to have a range error of less than 80ft.
Furthermore, (because I am lazy), uniform distribution will be use for dead time error (which is fine) and fuse time error (I should use normal distribution, but I am too lazy to make assumptions about the SD).
Since the target use is relatively low angle, I will take the projectile velocity from Okun's armour penetration table for common shell. (yes the higher elevation reduces MV)
Let's consider 3000yrds: projectile speed = 1697 ft per second.

One more assumption, the FC do not have a significant range rate error if the projectile can be bring close enough to trigger VT fuse and with radar range rate in use as manuvers will produce more changes to deflection than range rate.

So,
Rnage error due to DT = 238*0.5 = 119 ft
Range error due to fuse time = 1697*0.15 ~255ft
Two errors are independent, so how to calculate this?
Consider if a shell has no DT error, what is the probability of it bursting with range error less than 80ft: simple, 160/(255*2)=0.314. *long and short included

How about if a shell has the maximum DT error?
So, DT error of 119ft long. For a shell to burst within 80ft of target, the fuse time error is between -39ft and -199ft.
So probability is still 160/(255*2)=0.314

That means the DT error is irrelevant because the fuse time error is much larger. The scaling factor at 3000 yard is
80/255=0.314

The math becomes more complicated if we use normal distribution for fuse time. But the idea remains the same: with a well trained crew, most of the error comes from fuse time. OTOH, if the gun crews have poor dead time discipline, and let say 1.5s of DT error, the reverses with even lower hit probability.

[dunmunro]

We know in practice, automatic mode in Mk37 is faster than rate control. We even have test data on its the probabilities for TTB in automaic mode using VT ammo. You are exaggerating to say that manuvers always defeat the FC solution of by Mk37. With gun crew with good dead time discipline, we can scale the kill probability of the test results.

OK, please do.

Let's do a rough estimate by using fuse time error of 0.15s and dead time error of 0.5s. Take the plane speed of 140knots=238 ft per second.

Assumptions: In the test, TTB are determined by burst within 100ft of the target, with over 95% within 80ft. If we replace VT fuse with MT fuse, for all the projectiles that could be triggered, only a fraction will burst within the radius.
In a simplified geometry, the MT fuse need to have a range error of less than 80ft.
Furthermore, (because I am lazy), uniform distribution will be use for dead time error (which is fine) and fuse time error (I should use normal distribution, but I am too lazy to make assumptions about the SD).
Since the target use is relatively low angle, I will take the projectile velocity from Okun's armour penetration table for common shell. (yes the higher elevation reduces MV)
Let's consider 3000yrds: projectile speed = 1697 ft per second.

One more assumption, the FC do not have a significant range rate error if the projectile can be bring close enough to trigger VT fuse and with radar range rate in use as manuvers will produce more changes to deflection than range rate.

So,
Rnage error due to DT = 238*0.5 = 119 ft
Range error due to fuse time = 1697*0.15 ~255ft
Two errors are independent, so how to calculate this?
Consider if a shell has no DT error, what is the probability of it bursting with range error less than 80ft: simple, 160/(255*2)=0.314. *long and short included

How about if a shell has the maximum DT error?
So, DT error of 119ft long. For a shell to burst within 80ft of target, the fuse time error is between -39ft and -199ft.
So probability is still 160/(255*2)=0.314

That means the DT error is irrelevant because the fuse time error is much larger. The scaling factor at 3000 yard is
80/255=0.314

The math becomes more complicated if we use normal distribution for fuse time. But the idea remains the same: with a well trained crew, most of the error comes from fuse time. OTOH, if the gun crews have poor dead time discipline, and let say 1.5s of DT error, the reverses with even lower hit probability.

You have to include target travel during the deadtime interval (typically ~4 secs for Mk37), then you have to create a potential target volume and allow for the possible target travel trajectories within that volume of space.

[dunmunro]

We have no way of knowing how many of the kills by 40mm and 20mm were seriously damaged by 5" fire before they got within range of the former, but the CIWS would always get credit for the kill.

Beyond CIWS range there was a larger number of ships (and CAP aircraft) firing on each aircraft = large multiplicity of kill claims . The number of ships firing on each aircraft diminished drastically when the aircraft reached CIWS range = greatly reduced number of ships making a kill claim.


long range fire = highly inflated kill claims.

[wmh829386]

You have to include target travel during the deadtime interval (typically ~4 secs for Mk37), then you have to create a potential target volume and allow for the possible target travel trajectories within that volume of space.

Please read the premise of the calculation. It is to produce a scaling factor for the post war drone test. All the shells that we considered it this exercise have been brought near the drone and burst. All that matters is how MT introduce range error compare to VT. Hence, there is no need to consider the entire 3D problem except for introducing a reasonable range cut off.

[ A burst of 80ft off in range + 80ft off in deflection = 113ft from target by Pythagoras. I talk advantage that 96.5% of the VT burst is within 80ft anyway but TTB is counted to 100ft.]

I also don't need to consider the target motion because, again, all the shells we are considering have been brought close to the drone.

Note that I have converted all errors from time to range. The whole exercise is based on the information from the drone test report, meaning there's no information about individual target path anyway.

[Byron Angel]

According to Porteous Mk6 and GRUS/GRUDOU and/or Flyplane was superior to Mk37.

Interested readers might wish to access the on-line (Navweaps) copy of the document "From Fellside to Flyplane" by Roger Porteous and read for themselves what was written; see Chapter 10 - "Sea Trials in HMS Broadsword" (pg 49). These initial sea trials of Flyplane took place in 1949 - 13 years AFTER development of the Mk37 GFCS had been commenced and 10 years AFTER Mk37 series production had commenced.

If anyone can identify the passage where Mr Porteous (either Iville or Roger) stated that "Mk6" or "GRUS+GRUDOU" was superior to Mk37, please let me know; I cannot seem to locate it.

Meanwhile, for reference -

> The first prototype GRUDOU (Gyro Rate Unit Deflection Oil Unit) was tested at Frazer Battery at the end of 1942 or early 1943. After a successful series of tests, GRUDOU was approved for production and fitting to all RN warships already fitted with HACS+GRU; this production and installation effort was finally completed by the end of 1944.

> The first prototype GRUS (Gyro Rate Unit Stabilizer) was not fitted to a RN warship (HMS Implacable) for testing until 24 Sep 1944; the test was successful and a production order for 25 units was consequently issued. The GRUS+GRUDOU combo did see action in the PTO aboard HMS Implacable, but it is quite uncertain whether any other British carriers in the Pacific were fitted with GRUS (see Admiral Vian's report; "From Fellside to Flyplane", page 39).

> Per "Naval Weapons of World War Two" by NJM Campbell (pp 18-19), the latest model Mk VI director with the latest Type 275 radar and the latest NRS (Naval Reflector Sight) Mk 2G was found to have unexpected problems. According to Campbell - "The original NRS (Naval Reflector Sight) Mk 2G, known in a later version as Gyro Deflection Sight (GDS Mk 1), was intended to put nearly all trajectories through the VT fuze circle up to at least 4000yd but trials in 1944-45 indicated that the limit was about half the above. The Simple Electric Deflection Calculator (SEDC) could provide a measure of tachymetric computation to 4000-5000yd and GRU to about 3000yd but the former was not immediately available and GRU had to be fitted below the director."


Byron

Maybe you have a different copy than me:

On page 51: 'Our Guns Stagger American Chiefs'....The guns succeeded in hitting high speed targets that United States gunners had never been able to get near...

and

Later Axbey told IP of a meeting in 1953 with Eric James 'an electrician in charge on HMS
Broadsword while on gun trials in America'. (James had joined Ferranti after leaving the
Service.) James told Axbey that '24 rocket targets were sent over the American guns - they
missed every one- and then on over the Broadsword's guns and they accounted for 23 out of
the 24. The one was out of range'. 132

- - -


Maybe you have a different copy than me:

I have the copy sent to me by Cdr Roger Porteous. How about you?

- - -

On page 51: 'Our Guns Stagger American Chiefs'....The guns succeeded in hitting high speed targets that United States gunners had never been able to get near...

In all seriousness ..... you are actually presenting a photo of an a popular newspaper clipping? Wow! Did you miss the acerbic comment of Cdr Porteous - "As the Press put it". Really.

- - -

Later Axbey told IP of a meeting in 1953 with Eric James 'an electrician in charge on HMS
Broadsword while on gun trials in America'. (James had joined Ferranti after leaving the
Service.) James told Axbey that '24 rocket targets were sent over the American guns - they
missed every one- and then on over the Broadsword's guns and they accounted for 23 out of
the 24. The one was out of range'. 132

Do you have any information on the particulars of the event? What US ship was involved? What AA armament and fire control did she carry? Was this a formally organized competitive shoot between the two ships? If so, that would be quite unusual if it was indeed a gun trial to test HMS Broadsword's new Flyplane outfit. I have only the utmost admiration for Iville Porteous and his outstanding accomplishments. But, that having been said, the topic at the end of the day is not a comparison of Flyplane versus Mk37; it is a comparison of wartime HACS versus wartime Mk37. Kindly bear that in mind in future; it will make the discussion so much easier.

B

[wmh829386]

We have no way of knowing how many of the kills by 40mm and 20mm were seriously damaged by 5" fire before they got within range of the former, but the CIWS would always get credit for the kill.

Beyond CIWS range there was a larger number of ships (and CAP aircraft) firing on each aircraft = large multiplicity of kill claims . The number of ships firing on each aircraft diminished drastically when the aircraft reached CIWS range = greatly reduced number of ships making a kill claim.


long range fire = highly inflated kill claims.

That's not the case for a closely packed TF with screen placed around 1500 yards from CV. There will be far more weapons firing at the target inside the screen rather than outside the screen. If you consider the 40 mm Borfors, its effective range overlaps quite a lot with 5" too.

[Byron Angel]

Totally agree with wm.

An a/c attempting to fly between two adjacent DDs of a screen could easily have a half-dozen 20mm gunners firing upon it simultaneously. If the plane bursts into flames or loses control and crashes into the sea, half of those gunners may claim credit. In the inevitable fast-moving Adrenalin-filled chaos, it would be difficult indeed for any 3rd party reviewer to judge with confidence after the fact whether one or two or three a/c were actually shot down.

In the case of long range HAA fire, unless an approaching a/c is seen to catch fire or explode or perhaps disintegrate in flight, how can anyone understand the effect of their AA fire is from a distance of 4 or 5 miles? I’m not saying that multiple claims could not occur with distant fire; I’m saying that evidence of mortal damage is a good deal harder to detect from a great distance.

B

[dunmunro]

Interested readers might wish to access the on-line (Navweaps) copy of the document "From Fellside to Flyplane" by Roger Porteous and read for themselves what was written; see Chapter 10 - "Sea Trials in HMS Broadsword" (pg 49). These initial sea trials of Flyplane took place in 1949 - 13 years AFTER development of the Mk37 GFCS had been commenced and 10 years AFTER Mk37 series production had commenced.

If anyone can identify the passage where Mr Porteous (either Iville or Roger) stated that "Mk6" or "GRUS+GRUDOU" was superior to Mk37, please let me know; I cannot seem to locate it.

Meanwhile, for reference -

> The first prototype GRUDOU (Gyro Rate Unit Deflection Oil Unit) was tested at Frazer Battery at the end of 1942 or early 1943. After a successful series of tests, GRUDOU was approved for production and fitting to all RN warships already fitted with HACS+GRU; this production and installation effort was finally completed by the end of 1944.

> The first prototype GRUS (Gyro Rate Unit Stabilizer) was not fitted to a RN warship (HMS Implacable) for testing until 24 Sep 1944; the test was successful and a production order for 25 units was consequently issued. The GRUS+GRUDOU combo did see action in the PTO aboard HMS Implacable, but it is quite uncertain whether any other British carriers in the Pacific were fitted with GRUS (see Admiral Vian's report; "From Fellside to Flyplane", page 39).

> Per "Naval Weapons of World War Two" by NJM Campbell (pp 18-19), the latest model Mk VI director with the latest Type 275 radar and the latest NRS (Naval Reflector Sight) Mk 2G was found to have unexpected problems. According to Campbell - "The original NRS (Naval Reflector Sight) Mk 2G, known in a later version as Gyro Deflection Sight (GDS Mk 1), was intended to put nearly all trajectories through the VT fuze circle up to at least 4000yd but trials in 1944-45 indicated that the limit was about half the above. The Simple Electric Deflection Calculator (SEDC) could provide a measure of tachymetric computation to 4000-5000yd and GRU to about 3000yd but the former was not immediately available and GRU had to be fitted below the director."


Byron

Maybe you have a different copy than me:

On page 51: 'Our Guns Stagger American Chiefs'....The guns succeeded in hitting high speed targets that United States gunners had never been able to get near...

and

Later Axbey told IP of a meeting in 1953 with Eric James 'an electrician in charge on HMS
Broadsword while on gun trials in America'. (James had joined Ferranti after leaving the
Service.) James told Axbey that '24 rocket targets were sent over the American guns - they
missed every one- and then on over the Broadsword's guns and they accounted for 23 out of
the 24. The one was out of range'. 132

- - -


Maybe you have a different copy than me:

I have the copy sent to me by Cdr Roger Porteous. How about you?

- - -

On page 51: 'Our Guns Stagger American Chiefs'....The guns succeeded in hitting high speed targets that United States gunners had never been able to get near...

In all seriousness ..... you are actually presenting a photo of an a popular newspaper clipping? Wow! Did you miss the acerbic comment of Cdr Porteous - "As the Press put it". Really.

- - -

Later Axbey told IP of a meeting in 1953 with Eric James 'an electrician in charge on HMS
Broadsword while on gun trials in America'. (James had joined Ferranti after leaving the
Service.) James told Axbey that '24 rocket targets were sent over the American guns - they
missed every one- and then on over the Broadsword's guns and they accounted for 23 out of
the 24. The one was out of range'. 132

Do you have any information on the particulars of the event? What US ship was involved? What AA armament and fire control did she carry? Was this a formally organized competitive shoot between the two ships? If so, that would be quite unusual if it was indeed a gun trial to test HMS Broadsword's new Flyplane outfit. I have only the utmost admiration for Iville Porteous and his outstanding accomplishments. But, that having been said, the topic at the end of the day is not a comparison of Flyplane versus Mk37; it is a comparison of wartime HACS versus wartime Mk37. Kindly bear that in mind in future; it will make the discussion so much easier.

B

So now Roger Porteous is not an accurate source? OK, I am glad that we've cleared that up.

We were discussing the decision to put Mk37 onto RN ships that were due to commission in 1946 or later. The performance of latewar add-ons or potential replacements for HACS is quite relevant, especially if BuOrd was falsifying the actual efficacy of Mk37 in combat.

Porteous also provides data for FPS1 showing TTBs (page 51) that appear to be higher than for Mk37, but I guess we can't put much stock in that either.

[dunmunro]

You have to include target travel during the deadtime interval (typically ~4 secs for Mk37), then you have to create a potential target volume and allow for the possible target travel trajectories within that volume of space.

Please read the premise of the calculation. It is to produce a scaling factor for the post war drone test. All the shells that we considered it this exercise have been brought near the drone and burst. All that matters is how MT introduce range error compare to VT. Hence, there is no need to consider the entire 3D problem except for introducing a reasonable range cut off.

[ A burst of 80ft off in range + 80ft off in deflection = 113ft from target by Pythagoras. I talk advantage that 96.5% of the VT burst is within 80ft anyway but TTB is counted to 100ft.]

I also don't need to consider the target motion because, again, all the shells we are considering have been brought close to the drone.

Note that I have converted all errors from time to range. The whole exercise is based on the information from the drone test report, meaning there's no information about individual target path anyway.

The fuze timing order is based upon DT and ToF of the shell and therefore MK37 fuze timing is calculated by the FCS about 8 secs prior to firing the gun, at a future range of 3k yds. OTOH, target position data is updated continuously, and is based only upon ToF, or about 4 secs prior to firing at a future range of 3K yds.

If the target drone was flying a straightline course, then your assumptions would be valid, but it is actually flying a maneuvering course and the fuze timing is predicated upon the course that it was flying at the time of fuze prediction. Therefore fuze timing errors are likely to be considerably higher than simply the mechanical errors in the timing mechanism or load timing errors, because a maneuvering target is not likely to be at the predicted fuze timing range.

[dunmunro]

We have no way of knowing how many of the kills by 40mm and 20mm were seriously damaged by 5" fire before they got within range of the former, but the CIWS would always get credit for the kill.

Beyond CIWS range there was a larger number of ships (and CAP aircraft) firing on each aircraft = large multiplicity of kill claims . The number of ships firing on each aircraft diminished drastically when the aircraft reached CIWS range = greatly reduced number of ships making a kill claim.


long range fire = highly inflated kill claims.

That's not the case for a closely packed TF with screen placed around 1500 yards from CV. There will be far more weapons firing at the target inside the screen rather than outside the screen. If you consider the 40 mm Borfors, its effective range overlaps quite a lot with 5" too.

No. The screen, by definition, is designed so that each ship is outside the effective range of non SD (SD= self destruct) 20mm auto cannon ammo and the SD range of 40mm autocannon.

[Byron Angel]

Beyond CIWS range there was a larger number of ships (and CAP aircraft) firing on each aircraft = large multiplicity of kill claims . The number of ships firing on each aircraft diminished drastically when the aircraft reached CIWS range = greatly reduced number of ships making a kill claim.


long range fire = highly inflated kill claims.

That's not the case for a closely packed TF with screen placed around 1500 yards from CV. There will be far more weapons firing at the target inside the screen rather than outside the screen. If you consider the 40 mm Borfors, its effective range overlaps quite a lot with 5" too.

No. The screen, by definition, is designed so that each ship is outside the effective range of non SD (SD= self destruct) 20mm auto cannon ammo and the SD range of 40mm autocannon.

Untrue -
40mm self-destruct was about 4-5,000 yards. Complaints/comments about damage from fire directed by nearby friendly ships against intervening low flyers were commonplace in AA after-action reports all the way through to the end of the war.

"By March 1943 the Americans had concluded that the ideal was two carriers per task force, with the task forces concentrating for strikes and separating by at least 25 miles when air attack seemed imminent. The ideal screen was 20 to 24 destroyers and either six heavy cruisers, or two battleships and four antiaircraft cruisers. The destroyers were stationed in a circle at a radius of 1500 to 2500 yards from the center of the task force, with the heavier warships stationed closer to the carriers. In practice, there were simply not enough screening vessels for such extravagant protection, and most task groups consisted of three or four heavy or light carriers protected by fewer heavy warships and much fewer destroyers than the ideal. For example, Task Group 50.1 at Tarawa had two fleet and one light carrier screened by five heavy cruisers, one antiaircraft cruiser, and just eight destroyers.

The rapid growth of the U.S. Navy led to the adoption of additional levels of organization within a task force. These were the task group, which was often as large as the task forces of the early months of the war, and the task unit, which could be a single ship or a small group of ships within a task group.

References
Evans and Peattie (1997)
Friedman (2006)
The Pacific War Online Encyclopedia © 2013 by Kent G. Budge. Index


B

[wmh829386]

Beyond CIWS range there was a larger number of ships (and CAP aircraft) firing on each aircraft = large multiplicity of kill claims . The number of ships firing on each aircraft diminished drastically when the aircraft reached CIWS range = greatly reduced number of ships making a kill claim.


long range fire = highly inflated kill claims.

That's not the case for a closely packed TF with screen placed around 1500 yards from CV. There will be far more weapons firing at the target inside the screen rather than outside the screen. If you consider the 40 mm Borfors, its effective range overlaps quite a lot with 5" too.

No. The screen, by definition, is designed so that each ship is outside the effective range of non SD (SD= self destruct) 20mm auto cannon ammo and the SD range of 40mm autocannon.

????
When did USN use SD Bofors round and their Mk51 director has maximum range setting of 4000 yds.

[wmh829386]

You have to include target travel during the deadtime interval (typically ~4 secs for Mk37), then you have to create a potential target volume and allow for the possible target travel trajectories within that volume of space.

Please read the premise of the calculation. It is to produce a scaling factor for the post war drone test. All the shells that we considered it this exercise have been brought near the drone and burst. All that matters is how MT introduce range error compare to VT. Hence, there is no need to consider the entire 3D problem except for introducing a reasonable range cut off.

[ A burst of 80ft off in range + 80ft off in deflection = 113ft from target by Pythagoras. I talk advantage that 96.5% of the VT burst is within 80ft anyway but TTB is counted to 100ft.]

I also don't need to consider the target motion because, again, all the shells we are considering have been brought close to the drone.

Note that I have converted all errors from time to range. The whole exercise is based on the information from the drone test report, meaning there's no information about individual target path anyway.

The fuze timing order is based upon DT and ToF of the shell and therefore MK37 fuze timing is calculated by the FCS about 8 secs prior to firing the gun, at a future range of 3k yds. OTOH, target position data is updated continuously, and is based only upon ToF, or about 4 secs prior to firing at a future range of 3K yds.

If the target drone was flying a straightline course, then your assumptions would be valid, but it is actually flying a maneuvering course and the fuze timing is predicated upon the course that it was flying at the time of fuze prediction. Therefore fuze timing errors are likely to be considerably higher than simply the mechanical errors in the timing mechanism or load timing errors, because a maneuvering target is not likely to be at the predicted fuze timing range.

If you really understand what I was calculating, you can introduce your own estimate of the range error (in this case, similar to dead time, is a function of range rate) can be introduced as a third error.

However, I find that unlikely to contribute much as if a manuver is not radical enough to throw off deflection during ToF and the lag in the Mk1 solution, I doubt it can throw off the range by much.