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-   -   Top Flite B-25 ARF (Tecnical, tips, suggestions) (https://www.rcuniverse.com/forum/arf-rtf-75/6494380-top-flite-b-25-arf-tecnical-tips-suggestions.html)

krproton 01-25-2008 10:50 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

ORIGINAL: mtaboram

Hi Tim:

Thanks for your suggestions. I really appreciate it. As Doug mention you are the guy with this B-25. I will check all your post carefully. One specail question for you. I bought the Mc Daniel 466 individual Glow drivers for the engines. I will use OS Surpass 70. Do you have some pictures where I need install the module (orange) of this device?. If I decide use three blades propellers, which size do you recommend: 12x8 or 12x6?. I want use duralite Li-On redundant 2900 battery. what do you think about this selection. I don´t which radio do you use, but i want know if you could comment some special settings for this airplane. I will use JR 9303 2.4 Ghz.

Thanks a lot and I´m sorry for all my questions.


Hi Marlon.

I will try to answer your questions:

McDaniel on-board digital glow system -- I have not used an on-board glow battery, so I cannot provide any information. A few others have used this in their B-25, so maybe another person can assist.

3-blade propellers -- there have been many postings about this--including posts by my self. I have done some experimentation. In the end, I prefer the Master Airscrew 12 x 8. This is for the O.S. .70 Surpass II (same engine as yours). However, I recommend first flights with APC 13 x 6 2-blade. These provide the very best performance. After you have more flights in your B-25, then you can switch to the 3-blade.

DuraLite Li-ion battery -- Again, I have no experience with this type of battery. For receiver, I usually use NiCd, sometimes NiMh. I believe the battery you are considering is 7.4V and will require a regulator. I cannot recommend or "un" recommend this choice. Hopefully somebody else can provide info.

Radio -- I do not understand your question. The instruction manual for the B-25 provides information about how to mix the servos (throttle servos on separate channels, mixed electronically so you can reverse one of them and operate them separately, rudder and nose steering servo on separate channels, but mixed electronically so you can trim them separately, etc.). However, 2.4GHz is a good choice. I use Futaba radios and there is not yet a 2.4 GHz receiver available that will provide enough channels. Of course, JR also makes very good radio control systems so if this is your choice you will have good results. Again, I will have to defer to those who are using a JR radio to offer your assistance.

I guess I have answered only one of your four questions. Maybe others can help with the other three! [sm=72_72.gif]


norm 01-25-2008 10:54 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

This is a nice and clean installation in your hellcat. You do not seem to like butchering up cowls. The B-25 cowl is in fact 5.75 inch in diameter and compared to the hell cat the cowl on this plane is approx 9 inch wide by 12 inch high! and lots of room in there, which is not the case for the B-25, you have to strategically think of how to route your tubing and install peripherals like a fueler! Ok Electric guys wll also tell you to plan the wiring! I exagerate a bit here but you will find it tight. Look at the os 70 ultimate.


mtaboram 01-25-2008 11:17 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Thanks for your comments. I will review all these posts and consider all your recommendations. Surely I will contact you again in the near future.

mtaboram 01-25-2008 11:19 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
It´s Ok Tim. Many Thanks. I will continue in touch.


mtaboram 01-25-2008 11:39 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

In one of your post( 160) you mentioned 3 servos for rudder, using JR matchbox. Could you explain me why do you use three servos? one is for Gyro? do you have some pictures. I´m thinking install the gyro.

kochj 01-25-2008 11:43 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Thank you for the measurements Normand.
I don't have to have gas in my planes, I jsut prefer it....

I wish that Topflite(greatplanes) would have made this plane with that in mind...
I can't complain too much as Great planes have been wonderful with product support.

I just think that they could have made this plane a little bigger.....
If you compare the stance to a Kit (like that of 100+ ws) this one sits quite low...
I no way shape or form could have the time to put a kit together, I just wish it was bigger.....

Much like there new 150cc soon-to-be-released extra, they seem to miss the boat at times.
This is a small gripe though..... I am sure that those that have this plane are every bit happy to have and and run glow /or electric in it....


norm 01-25-2008 11:47 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Keep reading in the upcoming pages there are pictures. Now I'm at work but the rudder system uses 3 servos, 2 for the actual rudders and one for the noze wheel, all the system is connectec through the gyro. The servos are installed there. You do not need the match box, other than 2 y harness, one in the tail and one in the front for the noze wheel. The gyro does not need a Y. You connect the gyro in the rudder channel and from there your servos. Keep reading!!!

mike-rc 01-25-2008 12:22 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Hello Normund,
Thanks for plugging the aluminum levers. I made another run of about 15 sets, so if anyone wants them send $10.00 ($12.00 outside US) to my paypal address [email protected]. If you dont have paypal, send an email and I will give you my address to send payment.
It seems whenever they get mentioned in the thread, I sell a few sets. I have sold at least 40 sets already to guys around the globe!

Tim, I think it would take an awful lot of cycles before the alu levers ever wore into the struts.

europatc74 01-25-2008 02:44 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
CAUTION Note....I'm installing the In and Outboard Wing panels and have noted that the plastic plugs at the ends of the aluminum tubes can shift. The plugs at the end of my short tubes had recesseed over an inch inside the tube. You can fix this however. First run a screw threw the predrilled end. Then rap the other end on a hard surface. This will bring the plastic plug back in place. Important that this plug be at the ends because this is what you will be drilling and tapping into to secure the wing. If you do not run a screw through the predrilled side that plug will move when you rap the other side misaligning the predrilled holes. Once the plugs are in the correct position I used a little thin CA to secure them. FYI...

krproton 01-25-2008 03:46 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Thanks for the tip europatc74.

I'll look into this from my end.


europatc74 01-26-2008 06:24 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Just about completed the build..Testing the assembled retract system. I have the small tank. Never had an air system before so would ask what PSI to use. Also what is the Max for this size air tank. I tried 70 PSI as had been mentioned but does not seem to work very well. That's why I'm asking about the Max PSI for this set up.

norm 01-26-2008 06:30 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
You can crank it up to 110 psi

boss_rc 01-26-2008 09:38 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Tim ... this is a great forum, very helpful as I am now ready to begin the build on my B-25. Thanks for getting it going and your inputs. A question for you and others who are building this bird, I was about ready to order some Futaba S3115 servos for the rudders and noticed on the tech notes that the servo is not to be used with higher than 4.8 volts. At 38.9 oz-in of torque on 4.8 volts this little micro servo is powerful enough for the rudders but I was planning to use lithium ion batteries regulated to 6.0 volts because of the 13 servos I plan to use in my plane (using robart wheels and brakes). The S3114 would be an alternate as it will work fine with 6.0 volts, but it does not have nearly the torque of the S3115. I guess I could go check out specs, dimensions, torque etc on some other brand micro servo, but I would like to keep all radio and servo system Futaba. Anybody have a good idea here? I hate to use a separate 4.8 volt battery on the rudder servos. I suspect I'm probably missing something simple here...DJ

timothy thompson 01-26-2008 10:01 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
70 worked great i had 7 cycles . look for binding or leaks. use all new tubing and tees .on the spool valve make sure the speed restictors are out far enough and servo has linear movement. unscrew (restrictors) all the way out and try them that will give you a full pressure test. you can go up to 110 120 in the tanks

norm 01-26-2008 10:01 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Re servos.

You should use the JR 341 or the Hitec 85MG, the Hitec has metal gear and they both have over 45oz torque. Also once they are covered, in the hatch, you will never notice the brand and they all perform the same.

boss_rc 01-26-2008 10:15 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Norman ... thanks for quick reply on rudder servos. I checked the specs and dimensions on the Hitec 85 MG and I think I will go that route. I appreciate your suggestion there. Did you use the suggested Futaba 3003/3004 (ailerons, flaps, throttle, retract valve, nose gear etc) and 9001 (elevator) per instruction manual or did you upgrade to metal gear/higher torque on elevator, flaps, ailerons also? ... DJ

sevans16 01-26-2008 10:33 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
I bought a gang of Futaba 3152's. They are Digital 4.8V: .22sec & 69.4oz in/ 6V: .18 sec & 87oz in. They are less than 30.00 each.

boss_rc 01-26-2008 10:46 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
5132's look like a good choice for the money on control surfaces, plenty of torque and precision of digital. I have a bunch of 3003's and 3004's in my stuff looking for a home so I thought I'd put them in the B-25 since they are suggested in the assembly manual.

norm 01-26-2008 11:17 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
I used JR DS821 (30$) for the rest 72oz servos and one hs 5645MG (50$) Metal gear Hitec servo on the elevator 168oz overkill but great servo because of the metal gear and price.

fytrjok 01-27-2008 12:17 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
1 Attachment(s)
Well, when you've tweeked and dinked and tinkered till the cows come home and there's nothing else to do...you wait until the weather is just right and then you go fly! Today was the day. Sunny, 5 to 10 down the runway and not real crowded. I took my time with the engines and tuned them till they were sweet, topped off the tanks with noise and the batts with electrons and headed for the runway. Throttle was advanced and "Sweet Marie" tracked straight and true down the white line till she rotated and took to the air. My concerns about 2 OS 70's pulling a 21lb. airplane at this altitude were unfounded. I let her climb and began a gradual turn downwind. Four clicks right aileron and two clicks down elevator and she was hands off. Several passes revealed a sweet flying machine! The sound of those twin four strokers in sync is...a thing of beauty. I did find that the recommended 1/4" of down trim at full flaps was a bit much...3/8" is where I'll set it for the next flight. Landing was academic for this type of warbird...glidepath is moderated by throttle. I did come in a little hot as I do from time to time...especially on a test hop, but speed bled off quickly after touchdown and she came home to a happy and relieved pilot. Isn't that first full breath after a maiden flight refreshing! Ya gotta love this plane! The new Top Flite B25 is a beaut!! Here's some pics...

fytrjok 01-27-2008 12:25 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
1 Attachment(s)
A few more.....

fytrjok 01-27-2008 12:33 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
1 Attachment(s)
And the rest....better than Tranya!

camdyson 01-27-2008 04:58 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Well done - great pics. Where's the "beat-up" shot though?;) Man, is there anyone over there who DOESN'T fly off a sealed runway? We must be poor over here, or our road builders charge too much!

Hooking up the bomb bay actuators is reeeeaaaaalllllly testing my patience, but nearly there, then back to the instructions again:D


Cal Branton 01-27-2008 08:07 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
Congratulations on your first flight Doug. Great pictures. Mine is sitting in the basement ready to fly. Unfortunately we have 15-20 inches of snow on our runway. It will be a while before that "first flight" for me.

norm 01-27-2008 08:51 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
1 Attachment(s)
Congradulations fytrjok great maiden. I envvy you lucky guy ( no snow), and this b-25 looks amazing , those are great pictures.

Ok guys please dont laugh I only got 5 flights out of my B-25 before the snow. You can see the last picture before snow. Meanwhile this what I do for now, It is cold but better than nothing, take a look.

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