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In tests they are good for about 2,500 - 2,800 hp. After that and it's rapidly new engine time. Reno proves that one.
Of course since the Merlin started out at some 740 HP at low altitude, that is pretty darned good for a failure limit. Saying it fails at that power level is a pretty good compliment.
The ratings for GM-1 use on a Ta 152 were 20 minutes at a time presumably a full flow rate. There was 40 minutes total of the stuff.
Do you have any idea of the weight of the complete installation on a Ta 152? For Mosquitoes, the production installation weighed 475 lb. complete with 180 lb. of nitrous. As noted previously the test installation in a Spitfire V weighed 92 lbs. containing 15 lbs. of nitrous oxide.
Mods, anyone - Does this board have an ignore member capability? I can't seem to find it anywhere here. Thanks.
The difference here is most cases wouldn't be boosting power BEYOND existing military or emergency power ratings (or max continuous for boosted cruise sorts of scenarios) but to allow those ratings to be achieved well above their normal full throttle heights.You use N2O to boost the power level at full throttle only. Jetting it correctly at partial power is hardly ever done, not because it can't be done, but because it is waste. If you USE it at partial power, you are using it unnecessarily. Just move the throttle forward and you get the same effect wihtout using the Nitrous, right up until full power. At that point, it makes sense to use N2O if you want a 15 - 35%+ power shot for some period of time and if the engine components can handle the extra power without breaking.
I have already said in here that Merlin rods were good for 2500 - 2800 HP only, so using Nitrous for more than that might be reserved for setting world records or racing only. If you had a Merlin that made 1700 - 2200 HP. you could use Nitrous to get to 2500 HP. More than that and you are betting the farm against the livestock that you will make it home with a running engine.
Indeed, you'd have the same structural considerations of net power consumption (including that used to drive the supercharger) as with any engine ... applying too much N2O or LOX would be much like overboosting with a turbocharger and intercooler sufficient to keep the charge cool. Using nitrous boost at lower altitudes in low-gear is an interesting idea too, obviously also useful for single-speed supercarged engines limited to low altitudes in general, but still useful on multi-speed engines given the lesser power consumed by the supercharger (and less heat introduced into the charge).There is nothing to prevent us from using nitrous oxide at low altitude so long as the same power limits are observed to prevent bearing damage and to not exceed thermal limits as were imposed on use of MW50 (ADI injection in allied terminology). It was just more convenient and cheaper to use MW50 for low altitude and GM-1/Nitrous for high altitude. The DB605DB/DC went from about 1450hp on B4 to 1800hp on B4+MW50. So long as the nitrous was used judiciously and max power kept below the 1800hp certified for MW50 the engine should be fine. I rather suspect nitrous was kinder and less corrosive and as the RAF papers noted it relieved the supercharger of having to supply the power for over boosting.
Below is the 2015 Volkswaggon Tiguan people mover used by moms to drop of children at school and go shopping at supermarkets. It's 1.4L TSi engine has a specific output of 100hp/Litre on 95 (or less) RON with lean mixture thus handsomely exceeding the performance of the Merlin or Griffon. That's equal to the Merlin producing 2600hp on 95 octane.
I wonder how much power it makes at 3000rpm?