Sherman Fireflie's true top speed?

[Tank-Ace]

As far as I know, the brits just slapped their 17lbers into the (modified apparently) turret of an M4A4. I don't think they changed the transmission or engine. But limiting its RPM makes about as much sense as any other guess, since the M4's turret traverse was independent of its engine.

[gyrene81]

As far as I know, the brits just slapped their 17lbers into the (modified apparently) turret of an M4A4. I don't think they changed the transmission or engine. But limiting its RPM makes about as much sense as any other guess, since the M4's turret traverse was independent of its engine.

engine in the firefly was different from the shermans. there was also a weight difference, firefly being heavier. the information is easy to find, no need to speculate incorrectly.

Firefly Chrysler A57 multibank engine - 470hp
M4A3 75/76/105mm Ford GAA-III V-WC - 500hp

[SmokinLoon]

engine in the firefly was different from the shermans. there was also a weight difference, firefly being heavier. the information is easy to find, no need to speculate incorrectly.

Firefly Chrysler A57 multibank engine - 470hp
M4A3 75/76/105mm Ford GAA-III V-WC - 500hp

HP is about 1 of 10 criteria when comparing motors.    Far too much importance is placed on the "HP" value of an engine.  Gear ratios, torque, etc etc, all play a bigger role than most people know. 

[gyrene81]

HP is about 1 of 10 criteria when comparing motors.    Far too much importance is placed on the "HP" value of an engine.  Gear ratios, torque, etc etc, all play a bigger role than most people know. 

true, except for the fact that the transmission and gear ratios remained the same from the m4a1 to the m4a6...spicer manual synchromesh 5 speed

1st gear - 7.56:1
2nd gear - 3.11:1
3rd gear - 1.78:1
4th gear - 1.11:1
5th gear - 0.73:1
Reverse - 5.65:1

[Tank-Ace]

Whats the motor used on the M4A4, of which the Firefly is a modification? Chrysler A57.

I rest my case.


The M4 Sherman we have is a different model of M4 than the firefly is converted from.

[Squire]

The only modification to the Firefly of any note was the changing of the gun to the 17 Pounder. The engine remained unaltered. The turret was not changed either. There was no time for that as the variant was being modified with some urgency for the Normandy invasion in June 1944. 

All the sources I can find puts its best speed at 37-40 kph or 22-24 mph. I cant find a source anywhere giving it less than that, so far. Sources will disagree on 1 mph easily.

I cant find any varient of an "MBT" Sherman (one used as a tank not an engineer vehicle or some other variation), US (Army or Marines) or British or Canadian that had a top speed of less than 22 mph. The fastest variants seems to be the M4A3 versions with the Ford V8s.

20 mph seems a bit on the low end. At least from the sources I have seen. I dont have what HTC has on the vehicle.
 

[Butcher]

The only modification to the Firefly of any note was the changing of the gun to the 17 Pounder. The engine remained unaltered. The turret was not changed either. There was no time for that as the variant was being modified with some urgency for the Normandy invasion in June 1944. 

All the sources I can find puts its best speed at 37-40 kph or 22-24 mph. I cant find a source anywhere giving it less than that, so far. Sources will disagree on 1 mph easily.

I cant find any varient of an "MBT" Sherman (one used as a tank not an engineer vehicle or some other variation), US (Army or Marines) or British or Canadian that had a top speed of less than 22 mph. The fastest variants seems to be the M4A3 versions with the Ford V8s.

20 mph seems a bit on the low end. At least from the sources I have seen. I dont have what HTC has on the vehicle.

22.25mph is what roughly I am showing for the speed of the Firefly, no clue why its slower then an M4A4, being it had the same engine a Chrysler A57 Multibank engine and weigh's 34.8 tons vs the Firefly being 34.75 tons, However the M4A4 is rated at 25mph Road and 20mph Cross country, while I assume the Firefly is 22.25mph Road and some what slower maybe 19.75mph cross country.

My best guess at this is the Firefly should be 24-25mph Road as all the evidence I've collected really doesn't add up entirely, I would think its highly possible the documents are wrong, also another possibility is for example crews tended to add sandbags to the tanks for added protection - thus increasing weight, however I would believe these were field tested without any modifications for example the early versions of the Firefly didn't have wet storage for the ammunition as Fireflies risked Fire/explosion for the storage of rounds before the americans introduced this.

[Squire]

no clue why its slower then an M4A4, being it had the same engine

I think the explanation for that is quite simple. Sources vary. It really had the same speed roughly. You get differing quotes for the M4A4 and the Firefly both, so there is no surprise when you make comparisons they sometimes are different.

As far as "extra stuff" added on to the tank? all AFVs in WW2 had that. US, Brit, Canadian, Polish Shermans all had all sorts of things thrown on them. That is not modelled by HTC I would not think and I cant see it being a reason as there was no standard exta stuff to quantify. Each crew had their own decisions to sandbags, tracks, tents, bogies, netting, added camo, whatever. Its like asking what was a standard gypsy wagon fitted with. Good luck finding that.  

...I was taking a 2nd look at the M4A3(75) and M4A3(76) speeds as well. Most sources put them at between 29-32 mph. 26 mph also seems a bit on the low end which is the top speed for both in AH on lvl ground. The Shermans were not a slow tank. The 500 hp gas engine versions could clip along at a fairly brisk pace.

Is there a possibility with the upgrade they are missing the top gear? 

[Guppy35]

The only modification to the Firefly of any note was the changing of the gun to the 17 Pounder. The engine remained unaltered. The turret was not changed either. There was no time for that as the variant was being modified with some urgency for the Normandy invasion in June 1944. 

All the sources I can find puts its best speed at 37-40 kph or 22-24 mph. I cant find a source anywhere giving it less than that, so far. Sources will disagree on 1 mph easily.

I cant find any varient of an "MBT" Sherman (one used as a tank not an engineer vehicle or some other variation), US (Army or Marines) or British or Canadian that had a top speed of less than 22 mph. The fastest variants seems to be the M4A3 versions with the Ford V8s.

20 mph seems a bit on the low end. At least from the sources I have seen. I dont have what HTC has on the vehicle.
 

I think his point is that M4A4 that the Firefly was based on has a different engine then the M4A3 or M4A3(76)
Scanned this from Mark Hayward's book on the Firefly.  Looks like sustained speed on the road was 20mph.  Note the cross country speed.  A lot slower.   With the additional ammo carried and larger size of the shells, I imagine the weight increased a bit too along with the weight of the larger cannon.

Looks like HTC has it about right

[Butcher]

I think the explanation for that is quite simple. Sources vary. It really had the same speed roughly. You get differing quotes for the M4A4 and the Firefly both, so there is no surprise when you make comparisons they sometimes are different.

As far as "extra stuff" added on to the tank? all AFVs in WW2 had that. US, Brit, Canadian, Polish Shermans all had all sorts of things thrown on them. That is not modelled by HTC I would not think and I cant see it being a reason as there was no standard exta stuff to quantify. Each crew had their own decisions to sandbags, tracks, tents, bogies, netting, added camo, whatever. Its like asking what was a standard gypsy wagon fitted with. Good luck finding that.  

...I was taking a 2nd look at the M4A3(75) and M4A3(76) speeds as well. Most sources put them at between 29-32 mph. 26 mph also seems a bit on the low end which is the top speed for both in AH on lvl ground. The Shermans were not a slow tank. The 500 hp gas engine versions could clip along at a fairly brisk pace.

Is there a possibility with the upgrade they are missing the top gear?  

There's some interesting information, I have never seem the "Standard VC 25.2 mph" or 23 mph for both. Also throws a curve ball in saying sustained speed was 20 mph? Who made these comments because the article does not show".

I have continued my research and I continue to see 22mph for the Firefly, however I cannot explain once again why this tank is slower then the standard Sherman M4A3 and M4a4.

I would hope someone from HTC can say something here because really I am in the doghouse to explain this as my documents really gives no more information other then 22.25mph road.]

[Guppy35]

Look at the weight difference between a regular M4A4 (Standard VC) and the M4A4 Firefly.  3 ton difference.  Seems like it would make a difference in speed.

[Squire]

Tested offline with flat terrain. Most if not all are max speeds within 1 mph from any sources I can see.

Tiger I- 25 mph
Tiger II- 24 mph
Panzer IV H- 25 mph
Panther G- 28 mph
T-34/85- 32 mph
T-34/76- 34 mph - that is an absolute top end speed on a road without a doubt and thats its AH peformance.

If there is a class singled out to have their speeds at "sustained road" speeds they all seem to be Shermans. That an M4A3(75) is only 1 mph faster than a Tiger I is hard to justify Firefly debate aside. The Sherman family seems curiously slow compared to the AFVs above imho or conversely the tanks on the first list are too fast if we are using "sustained speeds" and not "max speeds". 

Tested same base:

Firefly- 20 mph
M4A3(75)- 26 mph
M4A3(76)- 26 mph (2 tons heavier than the 75 version).

[Guppy35]

Interesting.  I've never been a numbers person, but the line has always been that the Sherman used it's speed and mobility to try and deal with Tigers and Panthers.  Doesn't make sense if it's slower then a Tiger.

[321BAR]

Interesting.  I've never been a numbers person, but the line has always been that the Sherman used it's speed and mobility to try and deal with Tigers and Panthers.  Doesn't make sense if it's slower then a Tiger.

youre thinking of M4A3s not the firefly and also AH uses all the GV's max speeds not their true off road speeds. IRL the KT wouldnt go faster than 5mph on dirt and the TigerI would have problems also. The M4s are lighter therefore faster also offroad IRL

[Squire]

http://afvdb.50megs.com/index.html

Interesting site that has some good info on the Sherman. The listed "sustained speeds" for the M4A3s are 26 mph and the Firefly as 20 mph. Same as AH. The trouble is of course as stated above the other GVs in the game use max speeds so its apples and oranges. It looks to me that all 3 Shermans in the game require a speed adjustment upwards. Either that or the other GVs need a downward adjustment from their max speeds. Its an honest mistake but I think that Tyrannis stumbled on to something here.