B-25 SIC rating

Somebody who's BTDT said it's no fun to get shot at but it's really fun when they miss. Or maybe Dave said that.

gismo said:
I suspect it's a whole lot more fun when you're not getting shot at.
Click to expand...
 
Last edited by a moderator:
From the procedures Dave posted:

"A decision to continue the takeoff with a rough running engine encountered late in the takeoff roll needs to be tempered with the knowledge that if the engine fails below approximately 125-135 MPH, the danger is from the uncontrollable roll into the dead engine and not the yaw. Below 125 MPH, you will have to pull so much power off to keep the wings level with full aileron and rudder applied that the aircraft will not be able to maintain altitude, let alone heading. In USAF pilot training we simply taught cadets that if they didn't have 145 MPH when the engine failed, pull back the power on the remaining engine and land straight ahead."

I wonder how long it takes to accelerate from 120 (lift off) to 145?? Did you do the same "accelerate in ground effect to blue line" that you do in your 58P?
 
Ted DuPuis said:
Hey, look what I found:

http://cgi.ebay.com/ebaymotors/B25-...wItemQQptZMotors_Aircraft?hash=item4a9ccd3c88

Dave, is this the plane you're using? Or is it a hoax?
Click to expand...

Yes Ted. That's a bit different than what I did, but same plane. The airshow business wasn't very profitable this year. I think they are trying to find ways to use the bird and raise some funds to keep it maintained and flying. If one thinks in terms of a King Air costing $1,200 per hour to fly with fuel, maintenance and return on equity considered, it's comparable.

Best,

Dave
 
TangoWhiskey said:
From the procedures Dave posted:

"A decision to continue the takeoff with a rough running engine encountered late in the takeoff roll needs to be tempered with the knowledge that if the engine fails below approximately 125-135 MPH, the danger is from the uncontrollable roll into the dead engine and not the yaw. Below 125 MPH, you will have to pull so much power off to keep the wings level with full aileron and rudder applied that the aircraft will not be able to maintain altitude, let alone heading. In USAF pilot training we simply taught cadets that if they didn't have 145 MPH when the engine failed, pull back the power on the remaining engine and land straight ahead."

I wonder how long it takes to accelerate from 120 (lift off) to 145?? Did you do the same "accelerate in ground effect to blue line" that you do in your 58P?
Click to expand...

Effectively yes, except we didn't worry about ground effect; just stayed low and ready to cut throttles until 145 mph. Acceleration was strong with the ship light.

From what Scott said, the P-38 had essentially the same engines with much less weight. If one lost an engine while slow, over they'd go.

Best,

Dave
 
Dave Siciliano said:
Yes Ted. That's a bit different than what I did, but same plane. The airshow business wasn't very profitable this year. I think they are trying to find ways to use the bird and raise some funds to keep it maintained and flying. If one thinks in terms of a King Air costing $1,200 per hour to fly with fuel, maintenance and return on equity considered, it's comparable.
Click to expand...

That makes sense. At ~$5,500 for 2.5 hours of flying time max, that's probably still a decent sum of cash towards maintenance, or at least something. Plus that price is reasonably affordable (as far as aviation ratings that you might not use go, anyway). Makes me want to go do it.

Hey, Santa! I've been good this year. Want to buy me... ;)
 
Huh? Silly me, I thought the Lightnings had V-12 Allisons.

Dave Siciliano said:
Effectively yes, except we didn't worry about ground effect; just stayed low and ready to cut throttles until 145 mph. Acceleration was strong with the ship light.

From what Scott said, the P-38 had essentially the same engines with much less weight. If one lost an engine while slow, over they'd go.

Best,

Dave
Click to expand...
 
Wayne: I didn't ask. I think he may have been comparing horsepower to weight ratio. Two big radials with a lot of power and half the weight, but I didn't ask. It sure could have been me as the messenger that got that a bit wrong. Gunny has time in the P-38 and knows all that stuff. With all the info I was trying to retain, I sure could have miscommunicated. How many ponies do the P-38 engines have and what's the weight with pilot and reasonable fuel? That may be the comparison he was trying to point out.

Best,

Dave
 
Thanks Steve. 1150 HP engines on each side and much lighter. I'll have to look up the R-2600-35 engine HP to compare. Don't see a weight on the P-58. The B-25 was near 24,000 pounds on takeoff.

Best,

Dave
 
Well, it varies by model but the combat operating wt was around 17,600 lbs for the later J model P-38, with a maximum of 22,000 lbs. The later J models had a takeoff hp rating of 1425, max continous of 1100, and a military power rating of 1600 hp.

p-38-tactical-chart.jpg


Dave Siciliano said:
Thanks Steve. 1150 HP engines on each side and much lighter. I'll have to look up the R-2600-35 engine HP to compare. Don't see a weight on the P-58. The B-25 was near 24,000 pounds on takeoff.

Best,

Dave
Click to expand...
 
As a less-than-ten hour student pilot, I got to fly Maytag's On-Mark B-26 conversion at COS. It was a maintenance hop to test a new oil radiator. and they made me fly it around in circles while they played with stuff, checked for leaks and checked temp gages, fittings, etc. Then he told me to nose it over and take us home, and I have never (other than the big biz jets) seen airspeed needles wind up and altimeter needles wind down at such rates. Fun in a way but somewhat scary for a newb.

And then it was over, I was reassigned to a seat in the back and we went back to Pete Field and that was it.



Dave Siciliano said:
Wayne: I didn't ask. I think he may have been comparing horsepower to weight ratio. Two big radials with a lot of power and half the weight, but I didn't ask. It sure could have been me as the messenger that got that a bit wrong. Gunny has time in the P-38 and knows all that stuff. With all the info I was trying to retain, I sure could have miscommunicated. How many ponies do the P-38 engines have and what's the weight with pilot and reasonable fuel? That may be the comparison he was trying to point out.

Best,

Dave
Click to expand...
 
wabower said:
As a less-than-ten hour student pilot, I got to fly Maytag's On-Mark B-26 conversion at COS.
Click to expand...

Was this the Douglas A-26 / B-26 or the Martin?


It was a maintenance hop to test a new oil radiator. and they made me fly it around in circles while they played with stuff, checked for leaks and checked temp gages, fittings, etc. Then he told me to nose it over and take us home, and I have never (other than the big biz jets) seen airspeed needles wind up and altimeter needles wind down at such rates. Fun in a way but somewhat scary for a newb.

And then it was over, I was reassigned to a seat in the back and we went back to Pete Field and that was it.
Click to expand...

Cool.

As best as I can determine, the first time my dad flew an airplane was in an A-26 over occupied Germany.:yikes:
 
I can't think of a better way to lose my hearing.

Cheers, Dave. The P-Baron is good prep for such an endeavor, and I'm glad you had the opportunity.

To everybody else, a clever B-25 pilot finds ways to have others pay for the opex. It's the only way to fly.

M
 
Ted DuPuis said:
That makes sense. At ~$5,500 for 2.5 hours of flying time max, that's probably still a decent sum of cash towards maintenance, or at least something. Plus that price is reasonably affordable (as far as aviation ratings that you might not use go, anyway). Makes me want to go do it.

Hey, Santa! I've been good this year. Want to buy me... ;)
Click to expand...

75 gal an hour/side = 150 gph at $4/gal x 2.5 = $1500 in fuel cost alone.

And how many cylinders we talking bout at overhaul?
 
Doggtyred said:
75 gal an hour/side = 150 gph at $4/gal x 2.5 = $1500 in fuel cost alone.

And how many cylinders we talking bout at overhaul?
Click to expand...

Only 14 cylinders per engine; supercharged in two rows. CHTs would get pretty high if one idled long. We pointed it into the wind to do the run up for the sake of cooling. Not being run as hard as designed for because 145 octane gas is no longer available. We only pulled 40" of MP; the gage went to 60.

Engine start: http://www.youtube.com/watch?v=5yNvOmt28qM

http://en.wikipedia.org/wiki/Wright_R-2600

Best,

Dave
 
Last edited:
Dave Siciliano said:
Only 14 cylinders per engine; supercharged in two rows. CHTs would get pretty high if one idled long. We pointed it into the wind to do the run up for the sake of cooling. Not being run as hard as designed for because 145 octane gas is no longer available. We only pulled 40" of MP; the gage went to 60.

Engine start: http://www.youtube.com/watch?v=5yNvOmt28qM

http://en.wikipedia.org/wiki/Wright_R-2600

Best,

Dave
Click to expand...

By the way the 75 GPH per engine was an estimate.. I didn't do the math or check a chart. I just remember that the 4 engined Boeing they restored flew and ditched (around 2001-2-3ish) on its maiden flight was only fueled with about 300 gallons.. then proceeded to have a multiple engine failure from fuel exhaustion before the hour was up.. the 300 gals what what the restorers could afford out of their pocket that fateful morning.

http://www.pprune.org/archive/index.php/t-48905.html

DOING the math.. at BSFC of .45 lbs/hp/hr, full rated HP in that puppy comes out to 120 gal/hr per engine.. and thats very very conservative given the supercharged nature of the engine.

Lotsa horses is lotsa fuel burn..
 
Doggtyred said:
DOING the math.. at BSFC of .45 lbs/hp/hr, full rated HP in that puppy comes out to 120 gal/hr per engine.. and thats very very conservative given the supercharged nature of the engine.

Lotsa horses is lotsa fuel burn..
Click to expand...

Your BSFCs on supercharged or turbocharged engines tend to be significantly higher at rated power than at cruise. Well, that's true for any engine, but the difference is more pronounced on engines with forced induction. 0.45 is a reasonable BSFC at a cruise power on a naturally aspirated engine. I don't know about the big radials, but I'd not expect them to be any more efficient with their relatively low compression ratios. 0.7 to 0.9 wouldn't surprise me for takeoff power, and 0.5-0.6 for cruise. Also, your rated BSFC is not full rich - full rich is richer than rated for cooling purposes. Supercharged engines (at least Lycomings) run worse BSFCs than turbocharged ones. I was told by an old engineer it was because driving the supercharger mechanically was less efficient than using a turbo. Makes sense.

Example: Most naturally aspirated Lycomings develop rated power at about 0.50 BSFC (+/- a bit). The turbocharged ones hover between about 0.65 (that's a Malibu engine, which is intercooled - a T182 engine might be a bit lower) and 0.75 (that's a TIGO-541 that puts out 450 hp with no intercooler). The IGSO-540-A1A was rated at 0.86.

So... 120 gph at takeoff power might quickly become 180-200 gph. With 4 engines, it doesn't take much time there to burn up 300 gallons of fuel.
 
I'd have to go look up the take off power/fuel flow settings. In cruise at 27-29" of MP/17 to 1900 RPM, fuel flow was between 150 and 190 gph.

Well, I poked around and found these settings:
Cruise power settings
29"/1900 140 to 210 GPH
28"/1800 130 to 200
27"/1700 120 to 185
The variances would be do to weight and condiitions (keeping CHTs cool).

Climb power (METO) 40" at 2400 rpm.

Best,

Dave
 
Ted DuPuis said:
Your BSFCs on supercharged or turbocharged engines tend to be significantly higher at rated power than at cruise.
Click to expand...

You are absolutely right on all counts.

I used the .45 as an approximation for several reasons..

Those big ass engines are already gonna use lots of fuel no matter what. Starting conservatively its still gonna be a BIG number.

The .45 is leaned, normal aspirated, for something like a Lyc.. I've heard .50-.55 for the horizontally opposed lycs with blowers on em. Superturbo'ed radials running full rich on take off... dont even wanna think about the fuel burn, but think that it took a LOT of war bonds to fill those tanks.

The engineer who told you was right.. The supercharger takes power away in the process of boosting (uses engine power/shaft horsepower), whereas the turbochargers and power recovery turbines recover some waste heat (up to 50% of the energy produced from the fuel is waste heat) and convert it to boost (Turbo) or shaft HP (power recovery)

I have heard but not confirmed, that many of these old birds have had the boost turned down, disabled, limited to a single stage, etc due to the fact they aren't hauling 5-10 tons of bombs to the flight levels anymore, so I really dont know if the bird is using neutered engines or not, which would effect the efficiency of the engine.
 
Doggtyred said:
The .45 is leaned, normal aspirated, for something like a Lyc.. I've heard .50-.55 for the horizontally opposed lycs with blowers on em.
Click to expand...

It's been a year or two since I was regularly doing mixture sweeps, but I generally recall seeing somewhere in the 0.42-0.45 for best economy on a naturally aspirated Lycomings, depends on the engine as certain ones have different characteristics. I haven't spent a lot of time doing mixture sweeps on turbocharged ones, and zero time running supercharged ones, so I'm less familiar with those. The turbo'd ones I seem to recall generally seeing in the 0.50-0.55 like you said. We haven't run any supercharged engines since well before I started.

Superturbo'ed radials running full rich on take off... dont even wanna think about the fuel burn, but think that it took a LOT of war bonds to fill those tanks.
Click to expand...

I don't want to think about those numbers, either, but I'd venture a guess in the 1-2 range. It makes my wallet hurt just watching the needles go up to 45 gph a side at takeoff power for a Navajo with TIO-540-A2Cs. :) Seeing numbers of somewhere between 1 and 2 wouldn't surprise me for takeoff power, though, and more for war emergency power (on engines that had that).

The engineer who told you was right.. The supercharger takes power away in the process of boosting (uses engine power/shaft horsepower), whereas the turbochargers and power recovery turbines recover some waste heat (up to 50% of the energy produced from the fuel is waste heat) and convert it to boost (Turbo) or shaft HP (power recovery)
Click to expand...

Yep, it makes sense, and from my car days it was always known that superchargers hurt mileage more than turbos (some turbocharged cars get better mileage than their naturally aspirated equivalents). Like I said, we haven't run any supercharged engines in a number of years, and I certainly haven't run any, so it's not something I have any first hand experience with. I've just read a few engine specs on the old supercharged units for fun.

I have heard but not confirmed, that many of these old birds have had the boost turned down, disabled, limited to a single stage, etc due to the fact they aren't hauling 5-10 tons of bombs to the flight levels anymore, so I really dont know if the bird is using neutered engines or not, which would effect the efficiency of the engine.
Click to expand...

As I understand it, the bigger issue hasn't been the weight they're hauling so much as the lack of availability of the high octane leaded fuel, so they've had to turn the boost down for detonation margin in order to run on 100LL. Those guys will be in a world of hurt if 100LL goes away and isn't replaced with some other fuel with similar or better anti-knock properties.
 
Dave Siciliano said:
Just the size of this monster was something to me. I've just never flown anything this large. It's a bit deceptive because the nose sticks out well forward of the cockpit: where the nose gunner sits. Not really viewable from the cockpit, but sticking out there.

When checking controls free and working, one uses a rear view mirror just above the canopy to the front left and right. One can see the rudder movement and horizontal stab back there. Ailerons popped up a bit above the wing when moved full travel.

One can see the mains down and the nose wheel reflection in the spinner on either side. One climbs in from under the plane on a ladder that comes in just behind the cockpit. Lots of stuff one shouldn't grab. Where one can grab is always apparent right after one really needed it!

Lots of controls and lots of fingers needed at the same time to do some things like starting the engines. Definitely a two person AC.

It's really cool to sit in the nose on an approach; and in the tail in flight. One just feels like they are out there on their own, and, it wouldn't take much to make that true!

Can't imagine sitting in either of those places and trying to fight off enemy fighters, or to watch the flack come up and hope it's not the day one gets hit.

Best,

Dave
Click to expand...


Dave,

I might have an opportunity to fly the B-25 in the near future and was wondering if you could post some pointers.

I've heard that the controls are quite heavy and can be a real challenge in maneuvers like steep turns. Did you find that to be true and if so, do you have any recommendations?

Thanks,
Andrew
 
Andrew: I didn't find it that heavy on the controls compared to the 58P I fly, but I was pretty pumped up. We didn't do anything over about a 30 degree turn. We pulled the engine back to zero thrust in cruse which is pretty tame stuff. You don't want to lose an engine below about 140 mph as it's difficult to keep the tail behind the plane due to differential thrust. Scott Purdue that hosted my flights might be better able to relate some of the plane's tendencies.

Best,

Dave
 
No problem! The SIC rating stuff was just fun and that's the way I approached it. While we did go into aircraft systems, W&B, etc. some, we didn't do it to the level one would do to be PIC. It was more an overview for understanding. This was more of a three-day come get an overview and fly the plane to a standard where you can be a help to the PIC. There are several points where it's a two person plane with all that's going on.

Hopefully, you'll just enjoy flying it. Then, dig into all the systems and details. The flight instructor can make a real difference. Scott is highly competent and great fun to fly with. He's was an AF fighter pilot and has flown a lot of war birds. He's with AA now and doing this for the joy of it.

Best,

Dave
 
Steve said:
Might consider getting a copy of this DVD

http://www.aeroclippervideo.com/How_to_Fly_the_B_25_Mitchell_DVD_Pilot_s_Manual_p/ava-013.htm

I have a VHS version of the first film on the DVD, but you probably want the copy of the pilot's manual that's also included on this DVD, too.

The VHS I have also has P-38, P-61, and A-26 initial checkout training films.
Click to expand...

Actually, I do have that DVD....only problem is that right now it's in my stateroom on the ship and I'm on the ground in Bahrain.....Have to wait another month or so before I can watch it.
 
You must log in or register to reply here.
Back
Top