speedy72vega

You would probably be fine with a 2S 10C pack. Most servos run on either 4.8 volts or 6 volts, and a 2s LiPo IS 7.4, so 2S would be plenty. With that many servos, I would most likely be wanting at least 2200ma, maybe 2500. That way, you would probably be able to get in a few flights between charges.

FallDownGoBoom

My Feedback: (1)

Bear:

I'm pretty much with Speedy here, I'd think a 22002S would be plenty of power. I also assume you're talking mechanical retracts? I measured the current draw of two JR RT-88 retract servos when operating the twin landing gear on my P51 Bluenose, and as I remember, total current draw never exceeded 1000ma. Even if you got to 1500ma for three retract servos, its for five seconds, so a 10C pack should be able to deliver several flights. If you're running pneumatics, it takes next to no power to push/pull the air-control valve.

I too was a bit concerned with the two separate battery issue, and making sure that one battery doesn't get drained faster than the other. I think the simple solution is to figure out how long each battery will last at full rate discharge, the limit flight times to 80/90% of that and monitor the amount of charge that goes into each battery. Compared to the motors, the amount of current running the control system is pretty minor. Could you use a voltage regulator instead of the UBEC?

BEAR-AvHistory

FDGB,

The factory optional retracts are pneumatics Robarts which cost about $30 less then the plane itself did. Looking at a few options including Spring Air or Hobby City pneumatics & the electric screw jack style like the Eflite Bonanza 15. Eflite will be releasing a heaver set this spring which might be suitable.

At this point, the plane still in the box, so I can consider pretty much anything that might be a good solution including a voltage regulator. I have never used one so it did not cross my mind till you suggested it.

Currently, I have the plane & have set aside a pair of Turnigy SK42-60 with 80amp Plush ESC's for power. If necessary I can swap in SK50-55's but believe the 42's are a better all round solution.

Will most likely order 4 4S4000 30C Turnigy batteries for main power & 2 Turnigy 2450mAh 2S 20C for secondary power.

speedy72vega

Bear, what size props are you planning on running? The reason I ask, the 42-60 motors are only 500Kv?? I think? You might not get the performance you would like on 4S packs with only 500Kv, unless you can run larger props. Not sure what the ground and fuselage clearance is on the B25, but I suspect it will limit you to 12" or 13" props max?
You might want to consider 5S packs instead of 4S. You can always back off of the throttle if there's too much power on 5S.
I run my DW on 5S packs with the 42-50 motors, and they're 650Kv spinning 12X6E props. I wish I still had more power, even with those!!! After I get it back together, I have some 12X8E props i'm going to try, but it will cut my flight times down a little.

BEAR-AvHistory

Speedy,

You are correct they are Kv500 motors.

I currently run the SK 42-60 on 5S4000/5000 in my Kyosho 7lb fighters with 13X8X3 MAS props which are one size up from the book. My Telemaster SK 50-55 also will use the 5S4000/5000 when it flys next week. The 94" Telemaster is running a 14X8X3 MAS prop which seems to have a lot of pull on the bench but the 12lb plane will be my biggest plane to date.

Was thinking of the S4, which means I will have to buy new batteries, because the manual for the B-25 calls for a Power 46-670Kv with 4S3850mAh to 4200mAh & 13X8 props. Not sure if its a size/weight thing but if I can actually use 5S4000/5000 I will save a quick $170 from not buying new 4S batteries. The plane also looks like 14X8X3 will have sufficient ground clearance. Again since I have a number of MAS 12/13/14" 3 blade props that is a few bucks more I will not have to spend.

Found a good H9/B-25 build mega thread, 381 posts, that I am slowly wading through to get some tips & actual in-flight results.

http://www.rcuniverse.com/forum/m_65..._1/key_/tm.htm

speedy72vega

If you decide on the 14" 3 blade props, you will most likely have to step down to 4S. You will probably overdraw them on 5S, too many RPM's.
Do you have a wattmeter? You could make some test runs on 5S and see what the numbers look like. I made a motor test stand out of some scrap wood I had in my garage that I use for testing motors before I put them on planes, takes all the hassle out of it. I also use it for testing ESC's and battery/prop combo's.

As a side note, i'm converting a .50 sized Bobcat to electric, and I have a 50-55-580 for that. The preliminary numbers look pretty impressive so far, I got 1380 watts out of it on 6S, spinning an 11X8.5 3 blade prop, with a 72 amp draw. That should make that plane fly pretty well, I think .

FallDownGoBoom

My Feedback: (1)

Bear:

Just a quick point on retracts (and yes, I've got the Robart tri-grear set for the B-25): unless you're flying off asphalt or closely mowed and smooth grass, you may just want to stay with fixed gear. Rough fields and retracts do not mix well. Our field isn't exceptionally rough, but I was flying an UltraSport 60 fitted with mechanical retracts and 3/16 struts, and normal takeoffs/landings would bend the wire enough that the wheels wouldn't line up with the wells. I also managed to go through two sets of the plastic mounts on less than perfect landings. Not the retract's fault, but landing an 8.5 lb airplane at 25mph creates a shock in the system, and beats up the mechanical components. One of the guys at our field also tried a set of cheap mechanicals in a 60 sized P51, and finally gave up and went to fixed gear. True, the plane will look better in the air, but if the gear don't come down when it's time to land... I'd rather not think belly landing a warbird.

But if retracts end up part of the plan, I'd use at least 3/8" diameter Robostruts and the Robostrut versions of the retracts, not the kind where you mount the struts on 3/16 wire stubs. I think you'd be fine with either the Robart or SpringAir models. If you go with pneumatics, then power requirements are negligible, an HS55 or 81 servo will easily move the air control valve. No opinion on the Hobbycity offerings, they look good on the web, but if there's a service problem I'm not sure where you'd go to get 'em fixed. And I don't know if they're designed to handle a heavy warbird.

Just my opinion.

BEAR-AvHistory

Our field is a smooth 300ft tarmac. Its backed up with a longer wider parallel cut grass runway & a secondary cut grass runway that "T"'s into the parallel runway.

There are pictures of the field, including the cover shot & an article on our "Fly for Tots" charity event in the March 2010 Model Aviation magazine.

http://www.modelaircraft.org/mag/

There is a fuel powered H9 B-25 in the club that has been around for a while, does candy drops, that flys on the Robart package.

Both the Robart & Spring Air for this model run 7/16 inch RoboStruts or similar Spring Air struts & all my Kyosho fighters have factory installed retracts which seem to be OK. When I contacted Spring Air they recommended the 700 series units. While I have seen some & experienced one in my Hein there are not that many retract issues at the field.

Hobby King is of interest because they look to be Robart clones but would not get them without checking them out.

BEAR-AvHistory

Speedy,

The watt meter shows the 14" prop on the SK42-60/500 pulled 57amp & 1078 watts on a 5S5000. The 13X8X3 drew 44amp & 835 watts both running through an 80amp ESC. The Hein's manual wanted 600-800watts so I went with the 13" prop which flys very nice.

Will put a battery in the Telemaster tonight & see what the 50-55 with the 14" prop pulls. I have run it before & its within spec for the motor & ESC but am having an old farts moment & can't remember either the numbers or where I wrote them down.[sm=confused.gif]

EDIT: Just realized I have EC3 connectors on the watt meter & the SK 50-55's ESC & battery have Generic Hobby City connectors. Will solder up some adaptors in the morning.

FallDownGoBoom

My Feedback: (1)

Oh you lucky man... a smooth field! I think you'd be in great shape with the 7/16 Robostruts and either the Robart or SpringAir offerings. Have a ball with 'em! You realize, of course, that it doesn't count unless you have the door open/geardown/door close sequence programmed into a pair of doors on each nacelle?

speedy72vega

Another progress update: The right wingtip is finally done and ready to cover except for the glass wingtip. It got a bit crunched in the crash, so i'm going to use finish epoxy and glass cloth to reinforce it before attaching it to the wingtip and covering it.
This wingtip seems to be the hardest part of this rebuild, the rest of it should be pretty straightforward.
Here's some pics so far........

speedy72vega

Well, I finally got the right wing tip done and covered. Unfortunately I wasn't able to put the playing card decal back on, it won't come off of the torn covering. I think I have another E-flite decal like the one on the other tip, at least it will match.
Now, on to the center wing damage...........

BEAR-AvHistory

Can you get a decal sheet from Horizon?

speedy72vega

I'm not sure. I looked all through the replacement parts they have listed, but no decal sheet. I could probably call and ask, but i'm afraid of what they will want for it, judging by the cost of the other replacement parts..............
If someone tried to rebuild one of these strictly from replacement parts, it would cost over $400.00!!!!!!! The whole kit is only $159.00 now, kinda hard to justify the cost of replacement parts. The center wing section alone is $109.00, the fuse is $119.00, wing tips are $41.00 each, Nacells $15.00 each, nose cone $11.00, not sure about the tail feathers. That's one of the reasons I decided to fix mine myself. That, and it was a gift from my wife.
I'll probably leave it like it is, I don't think it looks too bad.

Avaiojet

Speedie,

Can't you use a bit of heat to remove that decal? It could be simple vinyl.

Charles

speedy72vega

The decal is a very flimsy clear sticker, with the design printed on. I tried to see if it would peel off, and it won't without destroying it. I know when I first built my DW, the covering was very wrinkled, so I shrunk it up with a heat gun and iron, and whenever I got close to any of the decals, it didn't take much heat to distort them. I will try a little heat to see if it will come off, i'll let you know how it goes, thanks.

Avaiojet

Speedie,

Get a straight on photo of it. Send it to me and I'll make one to replace that one for free. Maybe make it a tad bigger? I'll do the "Wild" also? Whatever it takes. Just let me know.

What say?

Charles

speedy72vega

Wow Charles, that would be GREAT! I tried to take it off with my heat gun on low, and the clear layer separated from the decal. It looked like a protective film.
I will see if I can take a good picture. If I post it here on this thread, can you copy it from here? Or do you need me to e-mail it?

Thanks again!

speedy72vega

Here's a couple of pics Charles, let me know if these will work. I added a ruler for scale.

Avaiojet

Speedie,

I believe I already have the playing card art for "Duces Wild" the Warbird. I'll look. May be a bit different. Or I can make it like that.

Not a bad photo, yea right,

You would be better off sending me an exact full size tracing.

Am I correct in thinking the new graphic has to completely cover the old one? Are you pulling/removing that off. I see no other way?

The lettering needs work? Is that decal material or vinyl?

The model is improving. Good for you. Kudos.

Charles

Avaiojet

Here ya go!

Be looking sweet like this in no time.

I think you're going to need a full deck of cards.

Charles

speedy72vega

Thanks Charles. I have already recovered the wing with just the stripes, so the card decal can go anywhere I want. It will just stick on over the existing covering.
It was made of some type of lightweight plastic or vinyl, with a clear layer over the top. I'm not too concerned about duplicating the exact material, vinyl would be fine, or whatever material is the easiest to make.

Avaiojet

Speedie,

OK, I can make "that" double card you have in the photo. How many do you need?

What about the lettering, "Duces Wild." What do you need there?

Do you need black red or white vinyl material to help with the fix?

Charles

speedy72vega

Actually Charles, believe it or not, the only decal that suffered damage is the cards. All the rest of the decals are ok. As far as the covering, i'm using Monokote for the white, and self stick covering for the red and black. Unfortunately, I wasn't able to find an exact match for the red in self stick covering, you can see in the pics, it's just a shade darker, but i'm ok with that.
So, all I really need is the decal of the two cards. If you can make that one, I would appreciate it very much. I don't expect you to do it for nothing though, let me know what I can give you for it.
Thanks again .

Avaiojet

Speedie,

Modelers helping modelers. Nothing wrong with that.

Besides, I did say I would help you out for free. Just rave about me when you place the sticker. A photo would be nice. Certainly a better one.

PM me with your address.

Charles