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VF51_Flatspin
10-02-2004, 08:58 PM
Just saw an interesting show on the History Channel "Broken Wings" where they stated that on the B-17C, the #3 engine was the primary power source for much of the instrumentation inside the cockpit. It'd be cool if this was modelled when we get to fly the Fortress...unless of course it was fixed in later versions.

Yellonet
10-03-2004, 03:53 AM
I wonder if the attackers knew that... well, now they do http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif

Arm_slinger
10-03-2004, 06:42 AM
I thought it powered the hydraulics and electrical systems as well. Bit silly imo to have every, or near to every system hanging off of one engine.

Chuck_Older
10-03-2004, 07:09 AM
If you consider it from a few other standpoints, it's not such a bad idea-

Firstly, 3 of the 4 engines would be basically interchangable

Secondly, maintenance on 3 of the 4 would be easier- you wouldn't need speical tools and/or engine specific manuals for each and every engine

Thirdly, monitoring all those sytems if run off of one engine might be easier

Lastly, if the systems were spread out, and you had multiple problems, that might reduce engine power across the board, whereas if the #3 went bad and you lost most of your instruments and hydraulics and electrical, the plane stays in the air because 3 of 4 engines are still running. they had mechanical backup, like the famous landing gear crank.

Everyone seems to be adamant about how rugged the P-47 was, and how it could fly with a cylinder shot out...no mention of it being odd to power everything off of one engine when you have only one in the case of the P-47.

VF51_Flatspin
10-03-2004, 05:25 PM
This sort of thing is pretty natural in engine building I guess even today. For example, in my six cylinder car one cylinder is the primary source for the A/C (can't remember which though). Makes sense to me in a car, but in a warbird, seems more logical to have them ALL running ALL the systems, or at least two of them for the sake of redundancy. Considering that it was more than likely than not that you'd lose at least one engine every now and then. The flip side is that you'd probably lose a fair amt of horsepower in all the others as they struggled to pick up the slack of supplying electrical functions of a shot out engine.

Hmm...catch 22.

Future-
10-04-2004, 03:52 AM
I recently read that the B-17 D we will probably get with PF only featured minor changes compared to the C-model, so maybe the D will have this sort of "feature".

However, about the F-model, I do not know if that one had this too. Not to mention the G-model we have in FB.

Fliger747
10-04-2004, 10:29 AM
A point to remember is that the early B-17 hydraulic systems were relatively simple, no powered primary flight controls, no spoilers, just about 'no-nutt'n'! A sucessfull design philosiphy of the time was often 'less is more', reducing vunerabilities complexity and WEIGHT. A fair ammount of electrical power was required fo running everything from turrets in later models to heated flying suits. Most gyro instruments of the day were vacume powered, a simple and generally lightweight solution.

Given the large leap in power available, the B-29 was able to violate this and pave the way to more modern aircraft of higher performance.

munnst
10-05-2004, 12:52 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Fliger747:
A point to remember is that the early B-17 hydraulic systems were relatively simple, no powered primary flight controls, no spoilers, just about 'no-nutt'n'! A sucessfull design philosiphy of the time was often 'less is more', reducing vunerabilities complexity and WEIGHT. A fair ammount of electrical power was required fo running everything from turrets in later models to heated flying suits. Most gyro instruments of the day were vacume powered, a simple and generally lightweight solution.

Given the large leap in power available, the B-29 was able to violate this and pave the way to more modern aircraft of higher performance. <HR></BLOCKQUOTE>

B17 hydraulics. Did this aircraft have hydraulics?. The flight controls had no power assist and the turrets, gear were electric screw driven.

Aaron_GT
10-05-2004, 02:40 PM
It would be very nice to get B17D (B17-II was supposed to model from the C onwards but never did) as the B17D is VERY pretty.

LW_Icarus
10-05-2004, 03:15 PM
Quoted from Flatspin:

"This sort of thing is pretty natural in engine building I guess even today. For example, in my six cylinder car one cylinder is the primary source for the A/C (can't remember which though). Makes sense to me in a car, but in a warbird, seems more logical to have them ALL running ALL the systems, or at least two of them for the sake of redundancy."


In antique, modern or any car, the A/C is run by the engine, through a belt, by a compressor. All accessories run off the engine but engineers go to great pains to ensure all cylinders are equal, otherwise your engine would shudder.

Someone may have told you that the power drain was equal to about 1 cylinder of your 6 cylinder car. taxable HP is usually around 15 percent of your total, but varies car to car.

Taxable horsepower is that lost to accessories like the alternator, water pump, oil pump, etc. (anything that doesnt spin the tires or prop)

and yes, putting all the systems on one engine does make sense to me, and during WW2 they probably weren't anxious to give up the resources to do redundant systems.

TPN_Cephas
10-05-2004, 03:38 PM
I watched the same show and what the #3 engine ran was the vacuum pumps for the navigation instruments. This was fixed in the D model. The C model was in very limited production. The C model also had a very weak empennage that could not handle torsional stress. Later models had the extended vertical fin strake running along the top of the fuelage forward of the vert fin.

Fliger747
10-05-2004, 04:18 PM
The Pilots instrument panel does show a hydraulic pressure guage. I can't say this with sureity, that the LG MOTOR was hydraulic, but almost all aircraft of any size use hydraulic MOTORS or cylinders to operate gear and flaps because of the size and weight of electric systems necessary to operate temporary load items of large draw with any alacrity. This was particulary true in the era of DC systems.

Being about 2000 miles from any of my references, I'll have to apologize for going on what makes sense from a long time in aviation.

Regards!

DGC763
10-05-2004, 05:37 PM
Landing Gear, Flaps & Bomb bay doors would be my guess as to the use of hyd. power in B-17.

EFG_Zeb
10-06-2004, 07:51 AM
I know the B-17 pretty well for having worked on one ("Chuckie" at the Vintage Flying Museum in Fort Worth TX), it is a G model.
On the '17, the hydrolic pressure comes from an elecric motor (in the cockpit) and powers the brake system and cowl flaps.
Everything else is electrical (flaps, landing gear, bomb bay doors). The reason behind this is that an electrical system is more battle damage resistant than a hydrolic system. Besides, on the G model at least, all 4 engines had electical generators.
As for the power turrets, i'd have to check as we had no ball turret and only a dummy top turret.

owlwatcher
10-06-2004, 07:56 AM
Sorta OT
What is the small motor that is installed between the waist and tail position for.

EFG_Zeb
10-06-2004, 08:17 AM
Now if you're talking about "the fifth engine", that's the APU (Auxiliary power unit), a small one cylinder two stroke gasoline engine hooked to a generator, for starting and to help relieve the load on the batteries.
Back there was also the tail gear retraction motor (electrical), right in front of the horizontal tail plane. There were servos for the autopilot up there too.

owlwatcher
10-06-2004, 11:33 AM
the APU (Auxiliary power unit), a small one cylinder two stroke gasoline engine hooked to a generator, for starting and to help relieve the load on the batteries.

Thanks That is what I was asking about.

Fliger747
10-06-2004, 05:22 PM
Thanks for the info! When I flew the C-130 a whilst back most everything important 'combat wired' meaning there were two sets of wires to essential components.

Pretty hefty wiring pannel on the bulkhead behind the Pilot in the 17!

owlwatcher
10-06-2004, 09:25 PM
Went to the sorta air show with a old navy guy.
Was poking around a C-130.
He says they use to have three props , they have 5.
Then later we were laughting . The c-130 also was made of metal and all I saw was that composite stuff.
Alot of changes in the materal dept. with that design.

VF51_Flatspin
10-06-2004, 10:24 PM
Thanks for the clarification Icarus! No doubt my mechanic "dumbed-down" his explanation to me - rightfully sensing that my shirt 'n tie meant I didn't know beans about the guts of my car! Bloody Swedish engineers http://forums.ubi.com/images/smilies/35.gif

DL Moffet
10-09-2004, 07:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Chuck_Older:
If you consider it from a few other standpoints, it's not such a bad idea-

Firstly, 3 of the 4 engines would be basically interchangable

Secondly, maintenance on 3 of the 4 would be easier- you wouldn't need speical tools and/or engine specific manuals for each and every engine

Thirdly, monitoring all those sytems if run off of one engine might be easier

Lastly, if the systems were spread out, and you had multiple problems, that might reduce engine power across the board, whereas if the #3 went bad and you lost most of your instruments and hydraulics and electrical, the plane stays in the air because 3 of 4 engines are still running. they had mechanical backup, like the famous landing gear crank.

Everyone seems to be adamant about how rugged the P-47 was, and how it could fly with a cylinder shot out...no mention of it being odd to power everything off of one engine when you have only one in the case of the P-47. <HR></BLOCKQUOTE>

Someone who hasn't read about Bob Johnson's run-in with Egon Mayer, evidently. To prove how tough the P-47 was I shall relate this piece of history:

Robert Johnson, early in his career as a P-47 pilot had been on a Ramrod mission. In the course of the mission all 8 of his Ma Dueces (M2 .50 cal MG) had jammed. As a result he had aborted and vectored for his base in England. Along his way he looked over his shoulder and saw another radial engine fighter approaching, however he initially thought it was another Thunderbolt and ignored it. Looking again a minute later he suddenly realized that it was an FW-190A series (8, I believe). He immediately tried to evade, but the Kraut stuck to him glue. The Kraut pelted his Jug ruthlessly, plastering it with with fire from 4 20mm canons and 2 13mm (.50 Caliber) machine guns. Johnson's Jug took a pounding, but it wouldn't fall out of the sky. The German ceased fire and pulled up beside Johnson. Johnson saw the Jagdflieger look up and down his Thunderbolt, shake his head, then drop back and the chase began anew. Johnson took repeated hits from the powerful armament of the Focke-Wulf, but still his Jug flew. Finally, evidently, the Jagdflieger ran out of lead. He pulled up next to Johnson again, looked up and down his riddled fuselage, shook his head, then saluted and went on his way. Johnson's perforated Jug made it all the way back to his base. The Jagdflieger he had been unable to shake was Oberstleutnant Egon Mayer, JG 2, 102 Luftsieg experten who would be killed the next year on 2 March 1944.
The ruggedness of the P-47 is beyond question. It is not an assertion, it is a fact.