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

hi elojim,
i'm from Toulouse too...!!!!! where did you fly with this fabulous B!!!!
i'm at Blagnac .
lol writing in english to an Toulousain.... con...

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

Hi there,

I just got my TF B-25 kit and will be building it slowly over the next few months.  This thread has a bunch of great advice - many thanks to all who have contributed!!  I am planning to use 2 OS FS-72's and will also be installing the Wingspan bomb door and ERS system with 8 bombs.  I am out of channels on my radio system - 9 channel JR system - so gear door sequencing will need to wait for a possible future upgrade.  I am already using a channel expander to group the gear and on-board glow on one channel, and another expander to group the bomb doors and bomb release on a single channel.  That let me free up a channel for the gyro I am putting on the rudder/nose steering.

mechanicalfailures - I contacted MikeRC a few weeks ago regarding the metal door levers but unfortunately he doesn't have any left and says it's not worth it for him so set up to make just a few so I guess we are on our own there.  They don't look like it should be too hard to hand craft a pair, just a bit of a pain.

I am really looking forward to this build but am not in any rush as I need to get my flying skills up a bit anyway!!

Any advice on suitable pilot and gunner figres would be welcome.  The profile ones simply won't do but I am having trouble finding reasonably priced alternatives.

Ron.

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

Hi, nice video.

Here is a video of mine : http://www.youtube.com/watch?v=RmzwFAXGxf0

Elojim

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

Hi Christophe,

i think we already had somes conversations via SMS :) !

Usually i fly at Casltelnau, but I do my B-25 flights at Sabonneres : "Private" club in the south of Toulouse but long (200 m) runway as you can see.
Here is a video : http://www.youtube.com/watch?v=RmzwFAXGxf0.

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

Ron,

good luck with your build. Mine is nearly 2 years old now and I have about 50 flights on it. I do not have the aluminum gear door levers, I soaked the wooden ones in CA like they recommend and so far they have held up just fine. What didnt hold up fine was the door arms glued to the main gear doors, I needed to attach those with screws since the epoxy pulled off the doors.

If you fly off grass, watch the weight. Those OS 72s might struggle to pull your plane in the air by the time you add the bomb drop. I have robart retracts, gyro and onboard glow and takeoff performance is marginal off grass with OS 70s.

David

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

If you can go for the o.s. 81's, they lift off no problem off grass.
here is a vid too.

http://www.youtube.com/watch?v=grp_vpYgxfE

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

Nice job and choice of engines Guataoo, a maiden flight is always a good feeling that turns out as good as that.

congrats,

Normand

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

Thanks David, appreciate the tips. I believe I saw in an earlier post that JB Weld does a better job than epoxy with the door hinges. Hopefully I'll be OK with the FS-72's as I fly from a disused airfield so we have a 550ft asphalt runway (with some overrun at each end).

I am definitely watching the weight build up as I already need 2 batteries; one for bomb system, glow system, and flaps, and another for the RX and the rest of the servos, etc. If balance makes it necessary then I might add a second RX battery, making a total of three. Hopefully that won't be necessary.

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

JB weld really hold well...area really exposed to oil sprays from the engine and for some reason epoxy doesn't make it. The beaty with JB weld is if you are at the field and one hinge come off, you can clean quickly with alcool or windshield washer and glue temporairely with Med CA. mine has been holding temporairely since 10/2007!

Normand

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

Thanks Normand, JB Weld it is - that temporary repair of your sounds to be pretty permanent!

Appreciate the advice.

Ron.

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

Ronbell,

I have a similar setup except I'm using Saito 82's. I have the Wingspan bomb release and Top Turret along with two glow drivers, gyro on the rudder, landing lights, Robart retracts with brakes, etc. This plane is piggish (from me adding too much stuff) and I fly off grass and paved. Our paved runway is only 280 feet long and I can lift off at about 1/2 to 2/3rds of that using 30% fuel. Grass takes quite a bit more even with 10% flaps.

I haven't weighed it but I have 7 (yes 7) batteries in it. No flaming please. ;) I have two 5 cell NIMH receiver batteries, 1 bomb release 4 cell NIMH, two glow driver batteries (McDaniels 466, one in each nacelle), 1 AA for the top turret, and 1 nine volt for the landing lights. With all of this weight, it still flys fantastic and I'm not having trouble taking off (either grass or paved). I would have gone with the McDaniels twin glow driver but I already had the 466's.

I'm also using the JR 9503 and ran out of channels. Decided to use a second receiver and my old JR9303 to run the bomb bay doors, bomb release, top turret, and landing lights. My buddy gets to play bombadier and it's actually pretty fun to fly it together.

I will say that there aren't too many of the machine guns I haven't broke off. JB Weld puts them back together. If you're going with Robarts, order some additional nose gear pins as you'll eventually break them if you have less than perfect landings on grass (i.e. hot landings).

Michael at Wingspan models is great to work with!!!

Dave

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

Thanks Dave, that gives a lot of 'warm fuzzies' that my plan will work out OK. I agree with you regarding Michael at wingspan - really helpful and easy to get along with.

I have a 9303 radio system and have manged to squeeze everything into the 9 channels by doubling up the rudders/nosegear, gear/onboard glow,and bomb doors/release through JR channel expanders and matchbox units, and using the mixing functions of the transmitter. Took some head scratching but it looks like it should all work. I would have liked more trim control access to the nose steering and independent aileron channels but can't justify the cost of a 12X system (that would be a LOT of fuel!!).

I did some bench testing of electrical loads and decided to use a 5-cell NiMH to run the bomb doors, bomb release, gear servo, onboard glow (Sullivan), and flaps. The basic reasoning for this is:

- bomb release takes ~1A per pylon for less than 1 second. Since you can only release each of the 8 bombs once per flight that is not a significant mAH consumption and, since the doors/flaps/glow/gear are all inoperative during release, volts drop is not a concern.
- bomb doors are driven by a single retract servo so that is not huge consuption and again would be the only thing operating at that time from this battery.
- The onboard glow is set that it can only be activated (via the left slider) when the gear is down so it's up to me to ensure that it is only being used at appropriate times (starting, T/O, and landing).
- I put the flaps on here to remove any potential for RX brownouts due to an additional 4 digital servos kicking in at the same time during a critical, slow speed flight phase (saw a buddy lose a nice aircraft from that!!).

The RX, and all other flight servos will run from a separate 5-cell NiMH battery. I plan on using either 2300mAH or 2700mAH batteries for each. I am still toying with whether to run 2 identical RX batteries to the RX - I probably will, mainly to avoid volt drop issues from current surges through a single battery connector. If I go that path I will almost certainly use 2300mAH units as they are physically easier to locate.

If anyone sees anything undesireable (or downright stupid) about the above then please holler at me!!

Your point regarding the pins for the Robart nose strut is well taken - I have noted the multiple reports of these breaking and, even although we have an asphalt runway where I am supposed to land, the majority of my landings are less than perfect.

Ron.

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

Ron,

Sounds like you have it all under control. A thought about the batteries... without igniting a war or at least a huge debate, I'm moving from the 2700mah NIMH batteries to A123 for various reasons. Not sure if you're looking at the AA size cells for the 2300 or 2700 but I've read that the AA size can't really deliver without voltage drop depending on your setup. I've always used two of them with two switches into two different ports on the receiver and have never had a problem. Just prefer to go the A123 route at this time. You say you've done some bench testing so you're probably fine.

Take care!

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

Yes, point taken - the AA issue is what is behind my 2300/2700 vascillation. I have heard a lot of good things abour A123 batteries but am still kind of nervous of not being able to reliably monitor at the field for something drawing them down more than expected. It sounds like they run full bore until they suddenly don't! It's likely just me being my usual 'creature of habit' self. This will be a lengthy project so I have plenty of time to change my mind a few times http://www.rcuniverse.com/forum/js/f.../msn/49_49.gif

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

Ron, sent you a PM...

Dave

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

Hi,

to add scale i did the "rcdon" modification so i can close the gear door after the landing gear down.
For now (to prevent problem) I use two separate switches. But does anyone knows if there is a appropriate sequencer fonction on the Futaba 12FG (rcdon was using a 14) ? I did not find it.

Sequence after take-off :

1) door open
2) gear up
3) door closed

Sequence before landing :

1) door open
2)Gear down
3) door closed

Elojim

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

Deleted

SR

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

Elojim,

If you are using air retracts, the valve you are looking for is this one: http://www.up-1.com/uptwo.html

This is the sequence you're looking for,

Bonne chance!

Normand

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

Hey Elojim, I used this method with the 14mz, and this guide says it can also be done with the 12z, and 12fg.
http://downloads.hobbico.com/misc/fu...sequencing.pdf
It's in the futaba team tips

Here is a video of mine working: http://www.youtube.com/watch?v=ZBXcyFXj18Q

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

all can be done by the offset mixing in the T12:
OPEN RETRACT:
gear door open offset +100% delay 0
retract open +100% delay 4
gear door close offset -100% delay 6
CLOSE RETRACT:
gear door open offset +100% delay 0
retract up -100% delay 4
gear door close offset -100% delay 6

that's all.... if you want to set the gear open you just have to don't close the gear door at the end you stay with only 2 offset set up on your mixing menu... 2 min 30S of programing....

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

I am starting mine as a winter project.  Maybe this has already been raised but I'm trying to decide between a pair of O.S. 81 Fs-a's or Saito 82's.  Is anyone using either of these in their bird?</p>

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

I'm using the Saito 82's with 30% nitro and McDaniel 466 onboard glows. They're mounted inverted. Started out with Perry Pumps just like Norman but switched to normal muffler pressure. Reason had nothing to do with the pumps. Just had never used them and this was my first twin and I wanted to minimize new stuff.

Plenty of power with my heavy bird (see earlier post). I can lift off in 1/2 to 2/3rds of a paved 280 foot runway. Takes much longer on grass. Also use 10% flaps.

djstar

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

Hey all, my name Greg. I received my TF B25J back in the summer time and over the last several months have been collecting the gear. I have read this forum front to back and everywhere in between. I have used just about every link posted as well as looked at every pic and video. I've got a pretty good idea of what I plan on doing with my bird and it will include some mods and a tweak here and there. I don't want to limit myself here, because if my luck and skill can run out as long as folks like Normand and Speed Racer, I'll have plenty of time to revisit and add new mods in the future. For now, I am concentrating on mechanics and a few upgrades to looks. Panel lines, rivets and weathering are in order for the initial build. Wingspans turret and bomb bay are likely candidates for the future as well as a more detailed main and rear cockpit. I would like to say I was saddened by the news of Timothy (Awesome scale scratch detailer). I really enjoyed reading his posts and checking out the pics he would post. He was amazing and I would have liked an opportunity to chat with him but he was already gone by the time I reached this thread. I marvel at the people that have come and gone throughout the thread and the information exchanged within. I have to say, way to hang in there Normand. You have rode this wave from practically day one, simply amazing. Every body's planes have been special in their own ways and I have really enjoyed reading this. In fact, I just finished a 12 hour sit at my computer trying to finish this thread. I already started building my bird and once I got started reading this thread, I was afraid to keep building until I checked for all notes I could get on building. Whew! Now I am done and I can begin my own experience. So, without further ado:
Cowboy: I am running the duel 82 FA's from Saito, regular muffler pressure with no pumps. I actually settled on this choice before I read the first post in this thread. I have had my go rounds with O.S. four strokes and although O.S. two strokes are the cats meow in my book, I have never had luck tuning the fours. Now Saito in the other hand, I have had much luck with and have successfully tuned and run saitos to my flying pleasure and enjoyment. Couple that with my need to overpower everything I get my hands on and viola! Saito FA82b. I do plan on using the McDaniel glow drivers, one per engine and don't have plans to use a gyro for now, but like I said before, everything is subject to change. I would like to get this one air born by spring and at least some detail done by our clubs building contest, of which we do have an ARF entry category.
I have all but finished with the nacelles with minor work left on the cowls and dummy radials. I am bummed that MikeRC isn't making the gear door arms any longer because both of mine are already broken. Unfortunately, I didn't read the thread until after I started and progressed to this point. I had made replacement arms out of scrap ply, but I'm guessing they will last about as long as the originals. The trick is making those doors close and open easily so you don't have to "Slam" them. I have read allot about what could be going wrong and plan on doing a complete go through to fine tune mine so the gear door arms wont be as stressed. However, I do wish I could have gotten a couple of those arms from MikeRC. I guess I could try to make my own.
Anyway, I am pooped and want sleep. Literally have sat here all day to read this so I could actually resume building. Looking forward to getting restarted with all the knowledge I have read here. Much thanks to those who have contributed to this thread, still here or not, and thanks to "kryptonite" Tim (lol) for helping to design what sounds like a great bird. For all those just getting started on this build like me........Here we go!

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

Good luck Greg! She is a sweet airplane and a crowd pleaser. Sounds like we're alike in several ways. I always read through build threads on a new bird and log the page and post number along with the topic and then refer back to them throughout the build.

Norman is awesome and helped me with several questions. SR sent me a pair of spring hinges for the nose gear door out of the kindness of his heart! I did get a set of Mike's aluminum arms. Great work! Awesome people in this hobby and on this thread!!

I did do the Wingspan turret and bomb bay and put together a thread on those mods with lots of pictures on RCSCALEBUILDER. Might help you if you decide to go that route.

Nothing sounds as sweet as multi engines in sync screaming by!!! :)

Dave

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

Thanks, I am really looking forward to seeing this plane fly! I agree that the 50 hrs. stated on the box is unrealistic. I would like to know in what shape this plane would end up as if a guy could actually finish it in that amount of time. Hell, I have 50 hours in already and I have just gotten to the last stages of the nacelles. I imagine I have at least another 10 hours to finish those up before I even start on the surfaces and other gear up front. I mean, even if a person were to just build this one plain, with no extra anything, it would take well over 50 hours. Since sooooooo many planes have come and gone through my hangar, my best estimate would be that I have built about 25 ARF's and so far one kit. Even with my experience, I see at least 100 hours to flight ready. Then, count the engine run ins, the extra detail and tweaking before she even makes it to the field and your looking at 150 to 200 easily. But I guess it isn't really an issue, seeing how it's winter time here in Maryland and our flying season is three months away. I have packed up my winter this year since I have this one and a Goldburg trainer kit build I am doing for my son. I plan on putting bomb bay doors and nav lights in that one, so I should get some good building experience with that one. I like building kits, but honestly, being a single father of a four year old son, I barely have time to scratch my, well, you get it. I have to say though, the quality of this B25 ARF is fine. I could have seen a better set of tires/wheels (rubber at least) and maybe even an option for servo actuated gear doors for the price of the plane, but reading through the posts in this thread, I can understand why they weren't included from the start. The more I spend on this project, the more I wonder how bad the "pucker factor" will be on maiden! LOL Anyway, some building talk.
I decided to mount my Saito's at the 9 o'clock position.I did this for two reasons. The first was for the reliability factor of having the exhaust facing straight down, to help the engine get rid of extra unburnt fuel. I did this in hopes it would help to avoid load up and flame out on taxi out and most importantly the final approach where idle is needed. I have mounted many Saito's in the inverted position and although I agree with Normand that a properly tuned engine will run fine at any position, I am also of the opinion that said engines have been tuned and tweaked to almost perfection after many tanks of fuel. I didn't see myself waiting until that point to maiden the bird. This is my first twin and I certainly don't plan on breaking the screws in while in flight, but Saito's don't really come into their sweet spot for almost an entire season of flying. A compromise had to be made and I wanted the engine positioned to allow for the best flow and the 9 o'clock position seemed the best choice. The second reason was I wanted the ability to photograph the plane from one side or the other without any un-scale equipment hanging out. This way, I get the piece of mind I need with reliability and a clean side to take my photos from. I do plan on using the 466 glow drivers so I will have that little extra piece of mind as well. Plus, it's less cutting into the cowl for glow driver usage. I also agree with Normand that the "easy fueler" valve from great planes or dubro works great and I almost always use them except for trainers and open engine birds like that. They are great in cowl additions that almost always make for easy fueling. BUT, I have had one or two fail in operation in the past and with this kind of investment, both financially and labor wise, I decided to go with the tried and true three line set up. Again, less cutting into the cowl and less chance of another component failing in flight causing me pain. I say pain because when this bird goes in, and we all know every bird will eventually, it is going ot hurt. My dream is to fly this one several hundred times and enjoy it for years until I have to deal with the loss. I installed fuel filters on both engines and am trying my best to miss nothing as I build this one. So far, I think I am doing okay. Below is a couple images that I have so far. I plan on taking more photos as I progress. I'll keep posting them as I go.