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Old Dec 20, 2007, 01:18 PM
In NY's beautifull hills
staggerwing's Avatar
Binghamton Broome Cty, New York, United States
Joined Jun 2004
1,126 Posts
Rec'd kit today w/ no real surprizes other than one nacelle was too large to accept cowl . I played around w/ the heat gun & eventually got the cowl expanded to fit. If I didn't have a pc of solid aluminum stock the ID of the cowl to use as a roller for the sides, it would have been a disaster.Now I see why they don't save space & plastic bags by shipping the nacelles & cowls slid together--they probably found it impossible as they don't fit !
Instructions show (2) of the small plastic clear bubbles--rec'd one--did anybody get two, & where does it go ? (haven't yet spent time analyizing B17 details)
It will be awhile before I get to this, so will be looking forward to progress of others .
I have an idea for scale type retracts, but don't have time right now to lay it out on paper. (this is the FUN stuff !)
BTW, the mtrs & ESC's I chose from BP Hobbies are BP A2212-10 & BP 18 A in a combo price of $32.36 (X 4)

Bob
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Old Dec 20, 2007, 01:45 PM
UK Commercial RPAS Pilot
Scott Cuppello's Avatar
United Kingdom, England, Carlisle
Joined Mar 2007
2,596 Posts
Should be 1 x astro-dome & 1 x ball turret.
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Old Dec 21, 2007, 09:26 AM
It's me Glacier Girl
Joined Aug 2004
868 Posts
Robert, for forgiving machine guns, look no further then control rod tubes. Already have a hole in them so it looks like a gun barrel, little paint and it will add to the illusion. Bang em into something and they will bend out of the way. Easy enough to bend them back into shape if something goes awry. I've even gone as far as doubling up tubes so you have the smaller tube protruding slightly, kinda looks like a jacketed barrel then.

I got mine on Wed. Like the looks of the basic kit. Not real happy with no clear canopy on the nose. Hmm, will I guess have to vac form a new one, and maybe something for the tail gunner too.

Orrrrrrrr, was there ever a strafer version of the B17? Like they had on the B25?
Could mount multiple 50's in the nose, and not need the clear canopy. Oooooo wait a minute, need to do some digging, but there was the YB-17 that was built to shoot down the captured P38 Lightning that was picking off wounded B17s over Italy if I remember correctly. If memory serves me it had twin turrents on top and multiple nose guns, that were controlled by the pilot. Time to do some web surfing.
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Old Dec 21, 2007, 09:35 AM
It's me Glacier Girl
Joined Aug 2004
868 Posts
Found it, YB-17/ YB -40, here's the story on the battle.


One of the more interesting stories in the MTO was of the phantom P-38, which was causing trouble for many crippled bombers. Beginning on June 4, 1943, a crippled bomber was coming back from a mission against the island of Pantelleria. The crew was considering bailing out of their bomber when they spotted a P-38 coming closer. They immediately relaxed knowing it was coming to their aid. The crew continued to dump extra weight from the aircraft, including the guns and ammunition. Before the crew realized what happened, the P-38 erupted in gunfire and destroyed the B-17. The only survivor was the pilot, Lt. Harold Fisher. Fisher was rescued and was the target of fury from the fighter pilots by suggesting it was a friendly P-38 that shot them down.

Several weeks before Lt. Fisher's ordeal, a P-38 pilot was low on fuel and was lost. He actually made an emergency landing just outside of Sardinia. The pilot was captured before he was able to destroy his aircraft. Italian pilot, Lt. Guido Rossi came up with the idea of using this P-38 against the American bombers. Rossi's strategy was to wait until the bombers made their attacks. Rossi would then take off and scout around for stragglers. He actually used this technique to shoot down several bombers. Until Lt. Fisher, no other crews survived to tell of the P-38 shooting them down. The American commanders were under the assumption that these missing bombers just did not make it back just as many before them. Nobody thought a friendly aircraft was the cause.

After Fisher told his story, bombers crews were alerted to look for a lone P-38, which was posing as a friendly. Fisher came up with the idea of using a decoy B-17 to attract Rossi. Fisher's idea was approved and he took off in the experimental YB-40 gunship. This was simply a modified B-17, which had more armor and guns. He flew several missions lagging behind the rest of the formations, but never encountered Rossi. Intelligence was being gathered and the Allies finally learned the identity of the pilot. They also learned that his wife was living in Allied occupied Constantine. An artist actually used a picture of his wife to paint a nose art picture on Fisher's bomber, and included her name, Gina. On August 31, a B-17 raid struck Pisa. Fisher was flying among the bombers, and was actually damaged by enemy fighters. He recovered at a low altitude and had to feather two engines. Before lone, a lone P-38 was approaching and the crew was on high alert. Rossi, using very good English, contacted Fisher, just as he did on previous occasions. Rossi immediately noticed the nose art on the aircraft and spoke with Fisher. Fisher was still uncertain the pilot was Rossi and was chatting with Rossi normally. Fisher decided to bait this pilot to see if it was Rossi or not, and began talking about Gine and her location in Constantine. When Fisher was describing intimate details of their "relationship", Rossi lost his cool. He peeled off and began his attack. Fisher ordered all guns to open up on this P-38, and Rossi had to peel off trailing smoke. Rossi intended to ram the bomber, but began breaking up and could not maintain flight. He was able to ditch in the water and survived. Rossi was later picked up and taken prisoner. Fisher was awarded the Distinguished Flying Cross medal for his efforts. Fisher would survive the war, but was killed in a transport accident during the Berlin Airlift. Incidentally, Rossi was one of the mourners at his funeral.
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Old Dec 21, 2007, 10:51 AM
Wannabe B-26 pilot!
Matt Halton's Avatar
Southwold, Suffolk, UK.
Joined Nov 2002
4,895 Posts
2 weeks to go for me...

Not too long I suppose!
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Old Dec 21, 2007, 01:05 PM
Registered User
Hendersonville, TN
Joined Nov 2006
45 Posts
how about one big esc?

Couldn't you just use one esc, like maybe a 60a esc for the four motors? I know you can use 2 brushed motors with one esc but how about 4 brushless? I don't see why not. Weight savings too, and you wouldn't have to sync 4 esc to rev to the same rpm and start at the same throttle setting, and so on. Much simpler, and probably cheaper and lighter too... What do you think can this be done?
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Old Dec 21, 2007, 01:43 PM
Ahhgh! Not ANOTHER new plane!
Robert Stinson's Avatar
San Diego, CA
Joined Dec 2001
2,700 Posts
W&P; nope, it won't happen. Try it and see. The b/l ESC is a small computer chip that regulates the current and receives "feedback" from the motor to adjust the regulation. 2 or 4 motors will confuse the chip. You don't have to "sync" ESCs to get the same rpm's, the same ESC and the same motor will yield the same RPM. Take my word for it, if it could be done, it'd be done a long time ago. There are loads of multi-engine electrics out there.
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Old Dec 21, 2007, 07:14 PM
diligentia vis celeritas
gunracer's Avatar
Corona, CA
Joined Feb 2006
3,547 Posts
robert is correct about using a separate esc for each brushless motor...i've seen a few reports of people successfully running more than one bl motor off a single esc...but again these instances are few and far between...you don't want to risk reliability with a model this size...

also i think the esc actually regulates voltage...as you throttle up, the esc allows more volts to the motor and thus rpms and the current drawn increase...
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Old Dec 21, 2007, 07:31 PM
Registered User
shschon's Avatar
United States, CA, SF
Joined Aug 2004
2,362 Posts
Quote:
Originally Posted by gunracer
robert is correct about using a separate esc for each brushless motor...i've seen a few reports of people successfully running more than one bl motor off a single esc...but again these instances are few and far between...you don't want to risk reliability with a model this size...

also i think the esc actually regulates voltage...as you throttle up, the esc allows more volts to the motor and thus rpms and the current drawn increase...

Wrong! ESC control how often the motor receive energy from battery. Only the BEC part regulate voltage so that regardless of battery voltage the electronic parts sees the same 5V or 6V they are designed to work.
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Old Dec 22, 2007, 01:15 AM
diligentia vis celeritas
gunracer's Avatar
Corona, CA
Joined Feb 2006
3,547 Posts
energy from the battery?...in what form if not volts?...i agree with you about the bec regulating voltage to the rx but we were discussing escs and motors...
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Old Dec 22, 2007, 05:52 AM
In NY's beautifull hills
staggerwing's Avatar
Binghamton Broome Cty, New York, United States
Joined Jun 2004
1,126 Posts
C'mon guys, lets stick to the B17 topic & not get our wires hot about another.
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Old Dec 22, 2007, 09:10 AM
Oh no, not again!
jhspring's Avatar
United States, LA, Carencro
Joined Dec 2005
5,231 Posts
Hey Gun et al.

I think there is still a lot of confusion between brushed and brushless motors. The esc for a brushed system is a potentiometer that indeed regulates voltage to the motors and therefore rpm.

Brushless systems operate quite differently. The computer chip in the esc converts the dc of the battery to ac at the same voltage as the battery. The motor "sees" the full voltage at all times. Rpm in this case is regulated b/c the output to the motor is switched on and off very rapidly. (I think this is what sschon was referring to) This is why high switching rates are desirable, they make the motor run smoother at low rpms (i,e, when power is switched off more than on). This is also why esc's get hot at part throttle, and motors get hot at full throttle.

Wrt multiple motors on single esc's, some of the high end esc's, like Castle Creations can apparently run two motors. I have never heard of running any more than two on one esc. It is a crap shoot though, and especially if you are like me, and run cheap stuff, you run the risk of frying an esc or a motor. It is simpler and safer, and these days, fairly inexpensive, to run one esc per motor.

As a personal preference, I don't know why it is necessary to jump on someone's post if you disagree or think they have made a mistake. The forums for me are about learning and sharing ideas and it is a lot easier if you can say what's on your mind without worrying about getting blasted for your ideas.

Merry Christmas all,
Jeff
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Old Dec 22, 2007, 09:32 AM
Ahhgh! Not ANOTHER new plane!
Robert Stinson's Avatar
San Diego, CA
Joined Dec 2001
2,700 Posts
I have corresponded with Joe Ford, Castle Creations tech rep, on a number of occasions. He unequivocally states one ESC per motor for b/l. You MAY get 2 motors to start up off one ESC, but that's by chance. Imagine on final approach that you've throttled down, then need to throttle up - only one motor starts.

He also mentions over-current. If one motor doesn't start up, or stops because it's become de-synchronized, the other ESC gets a surge of current, it shuts down, and down you come. Or, if it doesn't have over-current protection, it's fire, then you come down.

I'm not willing to trust "it might work" to a multi-hundred dollar craft in the sky, so it's one ESC for each motor.
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Old Dec 22, 2007, 09:57 AM
diligentia vis celeritas
gunracer's Avatar
Corona, CA
Joined Feb 2006
3,547 Posts
jeff,

thanks for the info...i'm by no means an expert on this stuff and as you stated, i visit rcg to learn, enjoy and share ideas about the hobby...fwiw, i didn't take shschon's response as 'jumping' my post...it's all good...
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Old Dec 22, 2007, 10:39 AM
Registered User
shschon's Avatar
United States, CA, SF
Joined Aug 2004
2,362 Posts
Quote:
Originally Posted by jhspring
Hey Gun et al.

I think there is still a lot of confusion between brushed and brushless motors. The esc for a brushed system is a potentiometer that indeed regulates voltage to the motors and therefore rpm.

Brushless systems operate quite differently. The computer chip in the esc converts the dc of the battery to ac at the same voltage as the battery. The motor "sees" the full voltage at all times. Rpm in this case is regulated b/c the output to the motor is switched on and off very rapidly. (I think this is what sschon was referring to) This is why high switching rates are desirable, they make the motor run smoother at low rpms (i,e, when power is switched off more than on). This is also why esc's get hot at part throttle, and motors get hot at full throttle.

Wrt multiple motors on single esc's, some of the high end esc's, like Castle Creations can apparently run two motors. I have never heard of running any more than two on one esc. It is a crap shoot though, and especially if you are like me, and run cheap stuff, you run the risk of frying an esc or a motor. It is simpler and safer, and these days, fairly inexpensive, to run one esc per motor.

As a personal preference, I don't know why it is necessary to jump on someone's post if you disagree or think they have made a mistake. The forums for me are about learning and sharing ideas and it is a lot easier if you can say what's on your mind without worrying about getting blasted for your ideas.

Merry Christmas all,
Jeff

You are wrong on the hobby grade brushed motor ESCs we use on our RC aircrafts (What you said maybe true for dirt cheap toy motor controllers). We would all have been ripped off to buy any brushed ESC if brushed ESCs were just a simple POT(one buck gets you bunch of them) that changes voltages to the motor.

The brushed ESCs (e.g. Castle Creations Pixie series brushed ESCs) pulse the motor by switching on and off very rapidly that is why you find switching rate as a standard spec for the ESCs. It is also why some cheap ESCs generate electronic interference to traditional 72mHz receivers. A simple POT would never have any switching rate on its spec sheet and would never generate interference to 72mHz receivers. Also if brushed ESCs were just a POT the ESC would get hot quickly by itself when you just plug in the battery without running the motor.


When you move throttle to different position what it changes is the length of the working cycle ("motor on" period) each time the motor is switched on (I called it giving energy to the motor) vs the time the motor is turned off. These switching happens thousands of time each second (e.g. Castle Creations Pixie 7P has switching rate of 2800 Hz) so users do not detect the switching. All we see is how fast the motors turns.
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