Managing Manifold Pressure

[Reyco1987]

Alrighty fellas, I'm starting strong and simple with the Hurricane and learning a lot about complex engine management...however I can't find any information on "proper" manifold pressure usage/limitations. I understand using propeller pitch to regulate engine rpm to roughly 2600, but I've blown my motor a few times even with oil temps around 80. I feel like this has at least something to do with manifold pressure. Oh, and I've noticed the red tape on the manifold pressure gauge, and I'm not sure if it's bad to leave the pressure within it for any length of time...

...So does anyone have some input or a good source of info???

Thanks! :salute:

[ATAG_Freya]

Hello Reyco, welcome to the ATAG forums! Team Fusion have a wiki that has some very good info in it : http://www.theairtacticalassaultgroup.com/wiki/doku.php?id=start Also, speaking from personal experience, getting on teamspeak and asking for instruction and/or just asking questions will go a long way as well. There is also a flight school thread used to link up new flyers with any available players to arrange some one on one training sessions. Engine water temps and oil temps is important. For now keep the rads (water only in the RAF planes) full open until you develop the right habits, and keeping the prop pitch below 2800 is good practice. The more you fly, the more you will become used to all the various combinations of settings acceptable for keeping your engine alive, and you'll do it without even thinking about it. Sorry can't be more help right now! good luck!

[Roblex]

It is quite unusual to see a Merlin blow with the rpm at 2600 (apart from on the ground when you have no airflow over the radiator) unless you are using BCO. Is it the Oil or the Water that is failing?

Generally, you should take off with radiator fully open (100%) and 3000rpm (full pitch, full throttle) but a minute or two after take off you should reduce the rpm to no higher than 2800 by reducing the prop pitch. You should not increase the prop to 100% again until you are in the circuit to land and thus using reduced throttle so your revs are not high anyway. Someone correct me if I am wrong but I believe official RAF info told pilots that the engine was not rated to run at 3000rpm for more than 5 minutes. You can do it during slow turning combat to have better speed control and climb rate but personally I avoid doing that as in the heat of combat it is hard to remember to reduce it again or watch your engine temp.

Really, if your rpm is kept below 2750 the engine should easily do an hours sortie without failing. The only thing to watch is sustained steep climbs at low airspeed. I have not had an engine blow on me for a very long time unless it had been damaged by combat (or I forgot to open the rad before taking off :D) but I tend to climb at 200mph. I believe that climbing for over 10 minutes at 140mph, even with rpm set at 2750, can cause the engine to blow. Sorry if I am stating the obvious but using BCO for more than a few minutes at a time will also damage the engine.

[92 Sqn. Philstyle (QJ-P)]

Are you using an "a" variant?

[Reyco1987]

Currently I'm using the Hurricane I ROTOL.

I've yet to see any failures from excessive water temperature, it's always been the oil system failing. It seems weird because everything you guys have mentioned is what I've had in mind while flying, temps and rpm levels and all.

I'm not 100% sure, but I'm not using the BCOl, unless I'm not fully understanding it...am I able to go above 6 boost with it? Because I'll open the lever but still only get 6 boost maximum.

Thanks for the warm welcome and that link to the wiki, that will be quite helpful!:)

[Osprey]

You don't have the 100 octane variant so will not achieve more than 6.25lbs, the BCO on the 87oct variant is a red herring, you can pull it a ram that throttle, but you won't get a boost. Even so the full 12lbs with 'tit pulled' is only achievable to about 12kft, then it drops off to the full throttle height (FTH) of about 18kft

If you are blowing your rad then go faster, open the rad wider or use a lower RPM. The oil cooler is in the same intake as the water rad.

The thing is that pilots will welly the Merlin in game, in reality that red bar was there for a reason and from what I've read most of the time the pilots didn't go into it, not unless they needed to.

If you are a Hurricane jockey then check my sig, we have the largest gathering of Hurricane pilots anywhere in COD, at present 3 squadrons. Plenty of state-side guys on allied and axis too, always nice to have more people who appreciate this warhorse and want to fly historically to fly with us.

Enjoy

@Phil, the 'a' is just the wing type, like with the Spitfire. If the Hurricane is labelled version 'I' then it's just incorrectly labelled by not including the wing configuration in the marque, afaik.

[Mudcat]

Is there any common thread to when it blows? In a dive? low alt? high alt? Just flying straight and level? Does it occur at about the same time each flight? etc? Just trying to narrow it down so I can give you a more definite answer :salute:

[Kai-61]

I've been flying the Hurricane lately--switched for a change from the Bf-109--and if you follow the wiki manual it is a good place to start.

But simply:

+6 boost and 3000 RPM takeoff (+12 boost if you have 100 Oct and BCO)

+6 boost and 2850 RPM for 5 minute combat (+12 boost if you have 100 Oct and BCO)

+6 boost and 2600-2750 RPM for 30 minute climb

+4-+3 boost and 2600-2750 RPM for unlimited

Rads should full open at any RPM and boost when at low speeds--even for slower climbs if you want to be careful. I close to 50% for cruising in level flight.

With the above I haven't wrecked an engine yet. When I first started off steep climbs with higher RPMs would destroy the engine before the 30 minute mark and at temps that otherwise seemed to be below the max (upper 90's for oil and 120 I think for the glycol).

[ATAG_Jerry]

Hi

I've only been flying for a short while, but i noticed that if you don't warm up properly, the engine can also be damaged.

Cheers
Jerry.

[Osprey]

It's not historical to use BCO for takeoff afaik. You should however, use 20 degrees flap.

[Reyco1987]

Roger, good copy on all. Thanks a lot for the info! This is a great first impression for me.:thumbsup:

I've learned a few good tidbits from everyone's input. I feel confident I won't be doing any more self induced damage to my motor...now I just have to worry about people shooting at me...

Based on what Kai-61 mentioned, I must be keeping the boost too high during level flight because that seems to be the most common time I've had troubles. I may have been too restrictive with the radiator flap as well. I didn't realize or even consider the oil cooler being in the same intake as the water cooler...thanks for pointing that out, Osprey.

[Baffin]

Below are a pair of clickable pages from the actual Hurricane Pilots Notes (The Flight Manual). Documents like this are available online, usually free, after searching for them. Remember that in CLoD, however, none of this is required... Whatever works for you is never challenged but if you enjoy historically accurate operations, it's fun to look up how the veterans of the Battle of Britain actually operated their machines according to RAF guidance..

Please notice on the left page, the takeoff checklist which prescribes NO flaps for normal takeoffs and permits the use of 28° flaps and Boost cutout override if needed (Under attack, bad weather, short runway, soft field or high weight, etc.).

:hpyflying:

13502

[Osprey]

This is a manual for the IIC type, with a Merlin XX engine, possibly a IV with Merlin 24 (1600hp), given away by the mention of bomb and fueltank hardpoints. I appreciate that the routines may well be identical though. Do you have the same for the Ia?

[Baffin]

This is a manual for the IIC type, with a Merlin XX engine, possibly a IV with Merlin 24 (1600hp), given away by the mention of bomb and fueltank hardpoints. I appreciate that the routines may well be identical though. Do you have the same for the Ia?

Good catch! It's actually for the Type IIA, B, C, D and MK IV according to the title page. I have made the assumption that, except for operating limits, procedures are the same as earlier models for pilot training continuity. I could certainly have been wrong in that assumption. Apologies if I led anyone astray. I do not have a Hurricane Mk I or II manual.
:sorry:

[Osprey]

No probs, definitely worth finding out because I want to replace our flightschool take off videos. So much want to do so little time.....