The A2A Simulations Community

"Come share your passion for flight"
It is currently Wed Dec 13, 2017 7:29 pm

All times are UTC - 5 hours




Post new topic Reply to topic  [ 13 posts ] 
Author Message
 Post subject: Boost settings
PostPosted: Wed Aug 02, 2017 1:30 am 
Offline
Senior Airman
User avatar

Joined: Tue Nov 20, 2012 1:38 am
Posts: 150
Location: La Crosse, Wisconsin
What does everyone use for take off power? I know in my Mustang I stick to 55 inches using 100LL fuel and I'm curious as the proper boost settings and power schedule for the Mk IIb. Any help would be greatly appreciated as I want to make sure I am flying her properly.

_________________
Image
Image
Image
Image
Image
Image
Image


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Fri Aug 04, 2017 2:41 pm 
Offline
Airman

Joined: Fri Jul 21, 2017 4:23 am
Posts: 14
Location: South Coast England
NAA551WB wrote:
What does everyone use for take off power? I know in my Mustang I stick to 55 inches using 100LL fuel and I'm curious as the proper boost settings and power schedule for the Mk IIb. Any help would be greatly appreciated as I want to make sure I am flying her properly.



Well, don't do this yourself, this is just my way - read the manual, etc.
Ask people who are better at this than me. ;-)

First things first; what's the METAR, (critically; temperature/ pressure)? What's your altitude, etc? Has a BIG effect on Take Off performance. Scott is always going on about those things - for good reason.
Let's assume a steady 6 kts wind on the nose and QNH 1013. Temps are an average Summers day in England- so maybe 23 degrees.

Personally, taking the Spit off the ground in a leisurely manner from grass in the conditions above I'll have dialled in a little negative trim (just one notch down on the gauge), airscrew is set full forward. Before Takeoff is Checked. I'll have S-Taxied to the RWY start, checked my oil and water temps are in the green. Flight control surfaces are checked, etc.

Then I'm lined up. Nothing in the way. Rads full open. Then I'll release the brake, quickly nail about 2800 RPM - that puts about +4 psi through the Boost - (I've only got a few gallons sloshing around in the bottom tank of fuel for a circuit or two), I'll keep back pressure on the spade until she goes through 35 kts (watch that prop!), then I'll slowly go neutral.
The tail will lift at about 50 kts and she generally just takes herself off the ground when she's ready at around 70-80 kts or so. Let her do this on her own. Don't interfere.

Keep steady on the spade, just let her hold your hand. Stash the gear as soon as you're happy she's lifting nicely.
I won't be greedy for altitude 'til she hits 145 kts or so (unless there are trees in the way), then go into the climb.
As soon as I hit 180 kts I'll start pulling the prop back a little at time 'cos I'm flying now.

Try it. Clear skies.


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Fri Aug 04, 2017 8:52 pm 
Offline
Senior Airman
User avatar

Joined: Tue Nov 20, 2012 1:38 am
Posts: 150
Location: La Crosse, Wisconsin
Ok so 4+ on the boost thanks!

_________________
Image
Image
Image
Image
Image
Image
Image


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Sat Aug 05, 2017 12:45 am 
Offline
A2A Spitfire Crew Chief
User avatar

Joined: Tue Jul 29, 2008 11:41 pm
Posts: 4877
Location: The South West of the large island off the north coast of Tasmania
Not sure about the question???

There is a light brown handle thing on the left cockpit wall that sticks out a bit...just push that all the way until it stops and you will find that the Spit takes off :) :) :)

_________________
...Some say he never blinks, and that he roams around the woods at night foraging for Merlin parts...


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Sat Aug 05, 2017 1:13 am 
Offline
A2A Spitfire Crew Chief
User avatar

Joined: Tue Jul 29, 2008 11:41 pm
Posts: 4877
Location: The South West of the large island off the north coast of Tasmania
Seriously, takeoff BBMF style is 6lbs Boost for the II if memory serves. The one thing you DO need to watch is overspeeding the airscrew on takeoff.

You should be taking off with the pitch control at full forward which gives you maximum PRM. But as you build speed after takeoff this will bust 3000. So straight after raising the undercarriage, make sure to reduce RPM back off "the stop".

_________________
...Some say he never blinks, and that he roams around the woods at night foraging for Merlin parts...


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Mon Aug 07, 2017 2:08 pm 
Offline
Senior Airman
User avatar

Joined: Tue Nov 20, 2012 1:38 am
Posts: 150
Location: La Crosse, Wisconsin
Thanks Killratio, I'll follow what the BBMF does :) You'll have to forgive me as I'm used to mp and not Boost :)

_________________
Image
Image
Image
Image
Image
Image
Image


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Mon Aug 07, 2017 8:32 pm 
Offline
A2A Spitfire Crew Chief
User avatar

Joined: Tue Jul 29, 2008 11:41 pm
Posts: 4877
Location: The South West of the large island off the north coast of Tasmania
No forgiveness necessary. The Boost/MP requirements are different for different aircraft in any case....

Enjoy the Spit!

Oh and should have said... you will bust 3000 rpm on the II if you use full throttle for takeoff (+9 lbs per sq in). I am not sure if you will at +6. I've haven't tried that since Beta.

_________________
...Some say he never blinks, and that he roams around the woods at night foraging for Merlin parts...


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Thu Aug 10, 2017 10:17 pm 
Offline
Master Sergeant

Joined: Mon Aug 26, 2013 10:03 pm
Posts: 1087
Location: Perth, W. Aust
Only 3,000rpm on my +8lb boost takeoffs here. I like to give it the beans!! I do a Clarkson on each takeoff - "POWER!!!!!!" :lol: :lol:


Cheers,
Mike

_________________
ImageImageImage


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Fri Aug 11, 2017 4:22 am 
Offline
A2A Spitfire Crew Chief
User avatar

Joined: Tue Jul 29, 2008 11:41 pm
Posts: 4877
Location: The South West of the large island off the north coast of Tasmania
Thanks Mike,

I was sure 9lbs busted the max RPM but couldn't remember how far down the throttle it would still exceed it.

The Spit I is much easier in that respect but given that the "opening up" radiator temp is 70C not 60C, she gives you even less of a chance on the ground than the II (if you do it properly).

Fun fact... in the shooting of the Movie "Dunkirk" the spit landing on the beach had to be shut down straight away on landing due to overheating..such was the penalty for that long set up for landing, even AT idle RPM!


D

_________________
...Some say he never blinks, and that he roams around the woods at night foraging for Merlin parts...


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Fri Aug 11, 2017 9:17 pm 
Offline
Airman First Class
User avatar

Joined: Tue Oct 29, 2013 9:08 pm
Posts: 87
Location: KSEE
Interesting. My Spitfire IIA and IIB manual (a reproduction of the Air Ministry manual from July 1940) gives the following for takeoff:

Maximum RPM 3,000
Minimum RPM at maximum boost (+12 lb./sq.in.) 2,270,

And for climb:

Maximum RPM at maximum boost (+9 lb./sq.in.) 2850.

I imagine the BBMF are somewhat gentle with their aircraft. Since I seem to have a limitless supply of spare Merlins in my hangar, I'm going to be flying with these numbers in future.

_________________
Cub, Spit, P-51 Civ, 172, 180, Comanche, T-6, Connie.


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Sat Aug 12, 2017 12:08 am 
Offline
Master Sergeant

Joined: Mon Aug 26, 2013 10:03 pm
Posts: 1087
Location: Perth, W. Aust
Interesting, but if I recall, the boost gauge isn't marked beyond 8lb. Guess I'd best do what all my school reports used to say - must try harder!!! :lol: Regarding the boost settings quoted, I remember reading in Stanford Tuck's biography that, during the Battle of Britain, climb revs were 2,650 at max power. Alas, the book doesn't say which mark of Spitfire this applied to, but I was always under the impression that this was for the Mk I, which by August 1940 had all been upgraded to constant speed props.

Not surprised to hear they cooked the engine making that long glide for the Dunkirk movie. Hope they did it in one take. I've always understood that you lowered the undercarriage the moment immediately before the last possible moment. So long glides at low power with gear down will roast your engine, guaranteed.

But I DO wish A2A would complete that Mk V.....

Cheers,
Mike

_________________
ImageImageImage


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Sun Aug 13, 2017 12:49 am 
Offline
Master Sergeant

Joined: Mon Aug 26, 2013 10:03 pm
Posts: 1087
Location: Perth, W. Aust
Firewalled the throttle on take off last night. The prop didn't seem to want to come out of coarse pitch until I cycled the prop lever, then it was 3,000rpm all the way. Did a 40 mile flight with the prop set at 2,850 rpm, full throttle, radiator wide open, at low altitude with no apparent ill effects. I checked the engine compressions on landing and all was good.

So there you go. Give it hell. You can afford that new Merlin anyway :lol: :lol:


Cheers,
Mike

_________________
ImageImageImage


Top
 Profile  
 
 Post subject: Re: Boost settings
PostPosted: Mon Aug 14, 2017 1:59 pm 
Offline
Airman First Class
User avatar

Joined: Tue Oct 29, 2013 9:08 pm
Posts: 87
Location: KSEE
And for those who don't know, you need to turn off the boost cut-out control to get a (shaky) +12 lbs.

_________________
Cub, Spit, P-51 Civ, 172, 180, Comanche, T-6, Connie.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group