Go Back  RCU Forums > RC Airplanes > ARF or RTF
Reload this Page >

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

Community
Search
Notices
ARF or RTF Discuss ARF (Almost Ready to Fly) radio control airplanes here.

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

Thread Tools
 
Search this Thread
 
Old 06-14-2011, 08:04 PM
  #2851  
Speedracer2112
Senior Member
 
Speedracer2112's Avatar
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 542
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

ORIGINAL: gregory.aldrich1

Yes I have watched the video a few times to review the good and bad points and you certainly can hear the chatter. All friends and all meant well. A guy should feel lucky to have that much attention, right?

Holly smoke! I dont know how you flew. But you did. There was way to much talking for you to process. [&:] My plane commands the repect of a Park Zone Corsair at the field now. After watching her fly several hundred times shes old news.

I have a maiden video of an 10' ASM B-17g that all you can here in the background is a member trying to sell/give away his parakeets. Great stuff.

Other folks flipping switches for you is bad mojo. Before you know it someone will flip the wrong one and instead of flap youll have your gear up on landing.
My plane is very simple. Perfectly tunned motors by RPM and thermo, flaps on a slide bar and a retract switch right above the slide bar. Both worked with my left thumb and index finger by memory. My eyes never leave the plane. No Gyro. She tracks like shes on rails. Look at my last video, she never leaves the yellow line for over 350 feet.

Im at about $4 per flight now. My first plane was $1000 per flight.[&o] After my first flight I had to lay on the ground for a few moments. You can see Ive gotten over that now.

I have OS81-a's. I can fly at full throttle for over 15 minutes and land with extra fuel. Ive heard twins are a tad touchy if you loose a motor. Use a timer!!!

On the trimming of the plane. I had the issue of my right wing stalling on landing. It usually did this right at touch down so no big deal. (You can see it in the last videos landing.) It finally got to me so I wanted to see if I could correct it with mixing. I was trimming my plane to fly straight a full throttle useing the ailerons. I was wrong in doing this. Its rudder that needs corrected to counter act the high rotation of the motors at full throttle. To correct the problem I trimmed the plane at half throttle to fly hands free. Next I mixed in rudder with the throttle to counter the prop/motor rotational force. It took out over 75% of the aileron trim I was useing and I no longer had to fight the plane from drifting right on landings and stalling to the right. I will mention that I first tried to mix in aileron to my throttle to correct this. I nearly lost my plane three times before I got her to the ground. I think your gyro will correct the drifting but its always better to have a properly trimmed plane.

On the flaps, if you can program them to deploy slowly, DO IT. I have mine programed to deploy slowly and retract a little faster in case I need to bolt on a landing. This will stop any bad behavior by giving you time to react to the plane.

SR
Old 06-15-2011, 12:37 AM
  #2852  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Brad, after flying her for the first time, I can definitely see I was trying too hard to keep her airborne. Also watching the video makes that clear. I guess I ws just thinking how heavy it is would make it drop out of the sky if it got too slow. I'm thinking diferently now. Your right, speed is good, but I was trying to land at a pretty good clip. I'm sure that things will be different from now on.
Although I was running pretty much at full throttle the whole time I was flying, it all seemed to be in slow motion. Several people made comments about how fast she was and I was thinking the oposite, but after watching the video after the fact, I see she was moving along at a pretty good clip. I think it may be her size that threw me off a bit, as well as the first flight pucker effect I was dealing with. I have plans for a whole different attitude next time I go out.
Here is an interesting fact. I fueled up with an electric pump and also emptied her after the flight. Since I topped her off and went straight out to take off, I can pretty much say 99% of the fuel used was for flying. I flew pretty much full throttle the whole flight except for approaches and was airborne for aprox. 5 min +/-. After calculating the consumption of fuel, I realized I had half a tank left in each. So, I can safely fly for at least 8 minutes andstill have 2 to 3 minutes of buffer. That's with the Saito 82 b's. I mention this for anyone who is building their plane with these motors.
Anyway, I know allot about the plane now after that maiden that I didn't know before it. I know I don't like the built in elevator to flap mixing and will manually adjust. I know I need to slow my flap speed down a little slower than I already have it. I know I need to deploy full flaps on downwind leg before final turn in. I know I need to come off the throttles a little more to slow her down and not try to fly her in like I did. I also know how much time I have to safely fly and can set my timer accordingly. I also need to add some more expo into the elevator because it has more authority than I had imagined. Lastly, I think I will set my gyro up so after roll out and take off and flying, I will shut it off for landing. I believe I was fighting the rudders just a tad while I was trying to land. I'm guessing the last place I need the gyro is on final approach. The plane isn't under power and basically gliding in. An engine out at that point isn't going to kill me, although it will make "going around" impossible. But at least with the gyro shut down, I know I'll have full use of the rudders. So just a question Brad, am I to understand you don't use your gyro for flight and just for a straight roll out to rotation? If so, why? That would be a pretty expensive piece of equipment for such a small use. I got the gyro based on what Normand was saying and have been touting that the whole time. Will it work if I need it? I sure hope so.
I'm hoping this weekend at the field will be much more successful. So much so that my biggest problem will be not having enough fuel for the day! LOL
Old 06-15-2011, 10:52 AM
  #2853  
RCGuy41
Senior Member
 
Join Date: Nov 2005
Location: Lusby, MD
Posts: 486
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg,

As for your question about the gyro the best time to have it on is on takeoff turn off before first turn, and on final after last turn. The reasoning behind the maddness and you stated it in your last couple sentences, you were fighting the rudders, you know why; the gyro was trying to compensate for the yaw. While at altitude you can turn the gyro off and if there is an engine out your gyro switch should be close at hand. On initial takeoff and upon landing those are the worst two situations to have an engine go out, low and slow engine out makes for many small pieces of wood. When I fly the gyro gets turned off after takeoff and I remain high just incase of an engine out also being carefull when performing a low pass on the field. Don't want to jam the throttles to fast could also cause an engine out. We all learn and it's always work inprogress to say the least when flying multi engine RC planes. Normand has what over 100 flights, I'm over twenty, SR has probably close to a hundred, all in all I learn something new about this bird every time I fly her. I would be carefull, I have mixed my full flaps and elevator to the point when the flaps are fully deployed my elevator is almost 55% down providing nice level flight at 1/3rd throttle and coming into my down wind turn preparing for final. With my bird before I mixed my flaps and elevator, my bird would nose up causing me to input down elevator, try holding down elevator and a down wind turn to final, I almost lost my bird on one occastion due to over controlling her. That's when I started playing with my flap elevator mix, finding that sweet spot to keep her flying nice and level. Again we all learn and you do what's best for you and your flying skills. Enjoy your bird I do hope she gives you many years of flying enjoyment.
Old 06-15-2011, 04:52 PM
  #2854  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Brad, thanks for the advice. I'll do my best to learn her out as I go. I see the logic in the elevator mix, but damn, it almost cost me the bird on Saturday. If you watch the video, you can see her pitch down violently right before I touched down and that is when I hit the flaps. Again, I normally would deploy full flaps on the downwind leg, but I was trying to follow direction. I might try a tiny bit of mix this Sunday and see what happens while she is up high and plenty of time left in fuel so I can feel it out.

A message to everyone, Happy fathers day to any and all fathers out there. I am a proud daddy and my son and I will be doing what we enjoy most this fathers day, Flying airplanes! Yay!
Old 06-19-2011, 02:10 PM
  #2855  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey all,
Just wanted to give an update on my second trip out with the bomber. All went superb on my second and third flight. I wasn't nearly as nervous as I was the on the maiden and all the adjustments made by what I learned the first time out made the next two fairly non eventful. None eventful except for the excitement of flying this wonderful bird. I was even able to muster the courage to roll her and loop her once each just to get a better feel for how she acts. Managed to get a little more video and uploaded it to Youtube. Still loading actually due to it being in widescreen format. I'd include the link but it was nothing spectacular. I am going to ask a friend of mine who is very good at videography to film the next flight and I will bring her in low and close for the camera. My buddy dave took over 700 stills while in flight and I will post them as soon as he gets them to me.
The only problem I had was the nose gear pin. It got a little torqued when I cracked up the maiden landing and I bent it back into shape before going out today. But, because it was bent once and bent back, it was weak and kept bending back both times I flew her today. Going to have to replace it before I fly it again. Also planning on adding in the rubber grommit Normand added and hopefully between that and the new stronger pin, she will hold from then on out. Can anyone tell me how to order that pin? Appreciate the help if so.
Guess I'll have to start thinking about panel lines and such now. Looking forward to formation flight with Brad. Definitely going to get video of that one!

Greg
Old 06-19-2011, 03:55 PM
  #2856  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey all,
Second and third flights under my belt now after a trip to the field today. Mitchell flew like the wind and everything went perfect. Now that the initial jitters are done, I was really able to enjoy the bird. One thing though, can anyone tell me how I can go about ordering another main pin for the nose gear? Mine was bent on the maiden last week and now it wants to keep bending because it is week. I just need to get a couple more for replacements and I can't seem to find it on tower hobbies. Does anyone have a part number, either robart's or tower's?
Here are a couple good pics my buddy Dave took today, June 19, 2011.
Attached Thumbnails Click image for larger version

Name:	Zx71700.jpg
Views:	34
Size:	162.7 KB
ID:	1625411   Click image for larger version

Name:	Hc92942.jpg
Views:	31
Size:	192.9 KB
ID:	1625412  
Old 06-19-2011, 03:59 PM
  #2857  
RCGuy41
Senior Member
 
Join Date: Nov 2005
Location: Lusby, MD
Posts: 486
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg,

Go to Robarts and find TF B-25 gear, you can download the gear drawings which will have every single part evan down to the nose gear pin. Give Robarts a call and talk to their sales rep, should cost 12 bucks less shipping for two pins. I still have one if you need it.

Old 06-19-2011, 04:49 PM
  #2858  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Thanks Brad. Have the info and will be calling them tomorrow to order. I have a question. You fly off of grass right? Do you have issues with the pin bending? Do you use the grommet idea Normand suggests? Thanks,

Greg
Old 06-19-2011, 05:19 PM
  #2859  
RCGuy41
Senior Member
 
Join Date: Nov 2005
Location: Lusby, MD
Posts: 486
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey Greg,

Yes, Pax Aero is a grass field; as for my nose pin, mine broke two years ago from a high speed landing plus hitting a divit in the grass. Cracked and bent the pin and sice replacement have had zero problems, now I don't use the rubber groument. When landing I try to hit the mains first but as with anything time does take its toll and gear breaks. By the way would be a sight seeing two B-25s flying formation when your ready I can travel to your field.
Old 06-19-2011, 06:44 PM
  #2860  
ronbell
Member
 
Join Date: Jan 2010
Location: Snellville, GA
Posts: 71
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hi Greg,

Happy Father's Day and glad that today went so well for you.

The nose gear pin is simply a 3/16 axle pin shortened by about 1/8 inch. I don't have a part number for the axle on it's own but there are two in kit p/n ROB659 at a cost of around $5.50. Here is a link:

http://www.advantagehobby.com/produc...118162&cat=692

I've heard it said that the nosegear pin is softer metal but I don't buy that - felt exactly the same to me when I was grinding the flats on both. A friend has a Hanger9 B-25 and when he bent a nosegear pin I gave him a spare axle. He cut it to length with his dremmel and has been using it successfully since.

Ron.
Old 06-19-2011, 07:33 PM
  #2861  
djstar39
My Feedback: (4)
 
Join Date: Nov 2004
Location: Fort Wayne, IN
Posts: 270
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg,

I use the rubber grommet and it seems to help. I did break the pin once after a hot landing without much flair on grass. Ripped out the nose gear door and caused a little damage to the wood inside. Nothing major.... but those spring hinges that are used on the nose gear door are hard to come by. They don't sell them by themselves. Speedracer mailed me an extra set he had out of the goodness of his heart. (Keep in mind I've never met the guy... that's why I love this hobby). But yes, by all means replace that pin before you're replacing more stuff because of it breaking. I did just what Brad stated and called Robart and ordered a couple extra pins.

Awesome that you're past the maiden and are now starting to enjoy her. I flew mine last week down at the AMA field in Muncie, IN. First time she flew off asphalt.... wow, I'm really spoiled now!!!

Dave
Old 06-20-2011, 01:13 AM
  #2862  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Brad, yesterday while flying the 2nd and 3rd flights, I was able to grease both landings without any issue at all. The maiden last weekend tought me a few things about the plane and I made the propper adjustments. Changed the elevator compensation to just 20% which gave me about an 8th of an inch and also set a delay in speed so the elevator lowers slowly like the flaps do. Made a huge difference this time. Now the plane doesn't pitch and can be controlled in decent by the throttle, just the way I like it. Also, rearranged my gyro settings so it isn't fighting me during flight. I really wish we could eliminate the maiden flight jitters because this bird really is fairly easy to fly. Once I got past that I realized I was gynormously nervous for nothing. I could see taking her out everytime I fly, but two things will keep me from doing that. One, I can't fit another plane in my truck bed, so I can't enjoy any other planes on those days and two, it takes a friggin hour to clean her off! I probably don't help the situation by running a bit rich either, but after the motors break in a little more, the crankcase vent tubes should put out a little less goo. I've always been one to run my fours a little rich to ensure cool runs and long life, so I guess it is what it is. As far as a day out to fly them together, I am all for that! I ordered the parts and we could plan something for the next couple weeks if you like. I have your ph# so I'll drop you a line one of these evenings.It would be great if you could come to our warbird fly in as well and we could do it then too.
Ron, I thought as I was putting the nose gear in it was just an axle as well, but I haven't been able to find just axles on the tower site, so I ordered the same kit you gave me a link to as well as a new nose canopy set as I cracked it during the build. I appreciate the advice as I do everytime I get it here on this thread.
Dave, I recall the posts where SR sent those hinges to you and I feel the same way about this hobby. In most cases, guys in this hobby will do whatever they have to in helping. I'm also gald the maiden is over and I am now enjoying the flying. Best advice I could give anyone who is ready to maiden is relax, this bird is not as difficult to fly as one would think. But then the amount of money and time one puts in almost assuredly will cause anyone to be a bit nervous the first time she lifts off. Now that I am past that though, I'll start thinking about the other mods like panel lines and rivets and maybe even a bomb bay over the winter. Barring any unfortunate events, this one will be in my hanger for a long time. She really is a peach!

Greg

ps. Does anyone have three view drawings that they would be willing to email me? I'd like to consider starting on the panel lines and I could use some. Thanks.
Old 06-21-2011, 06:28 PM
  #2863  
Jyjkoz
Member
My Feedback: (1)
 
Join Date: Feb 2010
Location: Port St Lucie, FL
Posts: 84
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

I Purchased my B-25 about a year or so ago..I will soon be getting around to building it I am going to place an order for all the needed equiptment..I would love some help compiling a "shopping list of needed items" What servos are you guy using , what motors are generally used (im not opposed to any motor type) I was thinking 4S 70 or bigger? Gas? What are any other needed radio gear etc.. This will be my first twin! I have read that a gyro is used ...For the rudder?


ANY HELP WOULD BE GREATLY APPRECIATED!!
Old 06-22-2011, 01:43 AM
  #2864  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hi Jyjkoz, My name is Greg. I just finished mine and have flown it threee times so far. I can tell you what I use and I'm sure others will have different opinions about various components. First of all, the most important part, the engines. I use Saito 82's with 12x8 three bladed props. These engines have enough power to easily power the plane off of a grass runway and she runs along at a pretty good speed in the air. Check back a few posts and you will find the link to my maiden flight which ended not so great but you can easily see she has plenty of power. I use McDaniels (sonic tronics) glow drivers, one each for the engines.
I use JR servos everywhere but the rudders. I use standard servos for flaps and ailerons, high torque servos for the elevator and nose gear steering and Hitec 82 MG's on the rudders.
I use a matchbox to split signal to the rudder and nose gear so I can independantly trim each. I also use a matchbox to trim the flaps, but keep in mind you will need to run a seperate extension to each flap instead of a standard "Y" splitter as it states in the building instructions. I am using a Futaba GY401 gyro for rudder control and it does make things a little easier for take offs, landings and some piece of mind in case of an engine out while in flight.
The manual will tell you what extensions you need and of what lengths.
You will probably want to make some new main gear door levers out of metal instead of the supplied wood ones as they will not likely hold up under the stress of the cycling of gear.
I would highly recommend you read this entire thread from page one as there is very valuable pointers you will get, as well as some very interesting scale ideas. Hope this info gives you an idea of where to get started. The guys who still follow this thread will be happy to help and it's a great community to field any questions you have.

Good luck on the build and strap in because it's going to be a while. It takes 200 or better hours to build for most.

Greg
Old 06-22-2011, 07:18 AM
  #2865  
ronbell
Member
 
Join Date: Jan 2010
Location: Snellville, GA
Posts: 71
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Jyjkoz - welcome to the TF B-25 group!!!

My name is Ron and I am still building mine, currently stalled waiting for a machinist friend to make me custom manifold adapters to let me tuck my mufflers in a bit more neatly.

First, I would strongly recommend that you follow Greg's suggestion totake the time to read this entire thread from beginning to end. There is an enormous amount of great information and discussion around many of the options available to you. Many of the choices come down to personal preferences and available funding but understanding what the choices are, and the associated trade-offs, will help you to plan your approach.

I am using the following:

Engines - OS72-A's. I plan to use 12x8 3-blade props but will probably maiden with 13x6 2-blades.
Elevator and nose sterring servos - Spektrum A6020's
Rudder servos - JR DS388's
All other servos - JR DS821's
Receiver - JR 921

I have several optional items in mine, most of which fall into the 'nice to have' category, and a few in the 'just because I wanted it' category....

Gyro (optional) - JR 370
Matchboxes - one for rudder/nose steering and another to sync up the four flap servos.
Sullivan on-board glow driver - single unit driving both glow plugs.
Wingspan bomb door system and bomb release system.
Robart retracts
Robart unibrakes (not needed if you fly off grass, optional for asphalt) with proportional controller.
Channel expanders - one for the bomb door & release system and another for gear, glow, and brake activation control.

For batteries, I am currently intending to use three 6V, 2700mAh NiMH batteries - two for the RX and all primary flight controls, and the third to power the bomb door/release system, the glow driver, and the flaps. I may have to upgrade this third battery to a 4200mAh as the bomb release system takes a hefty current spike when set to release bombs simultaneously, rather than in sequence. The final decision will be made based on weight, CofG location, etc., during final system testing.

Please don't hesitate to ask questions. This is a great, really helpful group!!

Ron.


Old 06-22-2011, 09:31 AM
  #2866  
Thomas B
My Feedback: (4)
 
Join Date: Jul 2002
Location: Fort Worth, TX
Posts: 1,257
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey, gang...still seeking a source for a top turret. Damaged mine badly on the ground recently and Tower just extended the backorder guesstimate another month, till late July.

Sure wish they would do a better job on keeping parts in stock for their customers that spend significant money on a large ARF. Being out of needed parts for 3-4 months is really not good customer service.

If anyoe has any leads whatsoever for a top turret in stock somwhere or spare to their needs, please PM me.

One good thing about being down for this part is that I am taking time to install the working upper turret kit! However, cannot go any further until I get the clear turret.
Old 06-22-2011, 10:24 AM
  #2867  
Mustang Fever
Senior Member
My Feedback: (2)
 
Mustang Fever's Avatar
 
Join Date: Nov 2003
Location: Cadillac, MI
Posts: 3,225
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

I removed this because I'm having so much trouble uploading pictures. See below. Maybe
Old 06-22-2011, 10:32 AM
  #2868  
ronbell
Member
 
Join Date: Jan 2010
Location: Snellville, GA
Posts: 71
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey Thomas - I just checked Advantage Hobby and they are also out - saying late July. Sorry.

Ron.
Old 06-22-2011, 10:42 AM
  #2869  
Mustang Fever
Senior Member
My Feedback: (2)
 
Mustang Fever's Avatar
 
Join Date: Nov 2003
Location: Cadillac, MI
Posts: 3,225
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

yjkoz

I've had mine a year, and just love it. I went the simple route as I wanted a reliable, hassle free good flying airplane. (good flying = as light as possible.)

-I used the fixed gear in the kit. The nose strut is not strong enough, however, so I ended up replacing it with a Fults 1/4 scale unit. That is so heavy that it allowed me to remove almost all the ballast from the under the nose gunner's station. (Normally you need about a half a pound.) I drilled the plastic block out to accept the larger shaft, and used "pull-pull rods" for steering. (If you look closely at one of the pictures with all the wiring, you can see the nose steer servo kind of in the middle of things.) I have made some really awful landings with this setup and have had no damage to the gear or the airplane. I did swap out the wheels for some Dubro treaded lites. If I had it to do again, I'd get the Sullivan Skylite (plastic hubs). The Dubros work fine, but the Sullies look cooler. I cut holes in the gear doors to clear the wires, and screwed them all into closed position.

-All eight wing servos are Hitec HS325HBs. Note: make sure to take every one of those wing servo hatches (all 6 of the sob's) and bust the servo blocks off, then reglue them with epoxy. They don't do it right at the factory.

-Nosewheel servo is a Hitec HS475 and the elevator servo is a Futaba S3305. Rudder servos are HiTec HS82MGs.

-She's powered by a pair of OS55AX's, swinging MAS 12x6 three blade props at 10,250 RPM on the ground. My bird is faster than any of the four stroke (72-91) powered retractable gear ones I've flown with. The supplied prop nuts don't fit the smaller crankshafts, so I used a pair of heavy brass ones. They look cool, smooth out the idle, and help with getting the CG. I used Hayes regular 11oz tanks. They fit in the nacelles with a bit of modification, and are the correct size for the engines. Best of all, Hayes is easier to set up than any other kind of tank, and due to their barbed fittings, more reliable. I don't use a separate fill tube, as I put holes in cowling big enough to get pliers into for disconnecting/connecting the fuel lines from the carb. Nasty grass fields are no problem with this power setup, and she cruises nice at a little over half throttle. I relocated the throttle servos to the right side of the nacelles and right behind the engines to get a short, mostly straight wire pushrod run. I blocked off half of the "cowl flaps", on the side opposite the engine, to improve the cooling. (This forces air to flow past the engine, instead of next to it.) For the same reason, I closed up all the holes between the cyllinders on the fake engines.

-I didn't want to spend a lot of money on power distribution electronics, and I refuse to use Y cords ever since I lost a plane to one that had a cold solder joint, so to simplify the wiring I used two receivers, and basically split the airplane in half, left to right: right aileron and inboard flaps are on right Rx; left aileron and outboard flaps on left Rx; rudders on one Rx, nose steering on the other; Elevator on one of them; throttles split left and right. (This makes startup so much easier, as once #1 is running at a high idle I turn off its Rx to make starting the other engine easier.) I did not use a gyro on the rudders and don't feel it's necessary. I did not use any extensions: I got a roll of the HiTec heavy duty servo lead wire and a bunch of the 1/16 blue shrink wrap and solder in all the necessary wire lengths. Where I needed Ys, I soldered those too. The radio is Futaba 6EX 2.4. You can see how the antennas are routed at 90 degrees to each other using pieces of old flex tube. There is one EMS heavy duty switch/charge jack per Rx (left and right sides) and a Hydrimax 2000 NiMh pack for each Rx. You can see the switch just ahead of the right side 50 cals in the pic.

-I put cub yellow flashing on the LEs of the wing and the vertical tails to make her a little easier to pick out against a tree line.

-I counter torque weighted the right wing tip (engine displacement in cid times 2 times 2, or 2.2 ounces) This made a monster difference in the handling- there is so much torque to the left on this baby that turning right was difficult before I added the CT weight.

-She came out at exactly 18 pounds, will takeoff flaps down from a grass field in about 150 feet (no wind), and handles like a great big sport flyer. I set the CG at the rear most recommended limit, and highly encourage this.

I always, always, warm up and check both engines for 5-7 minutes before each outing, then shutdown and refuel for flight. I have the throttles pretty closely synched mechanically, by careful attention to the linkage. Once they are both warmed up, I use the needle valves and a tach for final synching. I can get them within 100 rpm of each other at wide open, and each has at least a 200 rpm "bump" on a pinch test so I'm not overleaning anything. Guys will tell you not to do this, but I find it works fine. Just don't try it without a tach. I change glow plugs every fall, and have never had an engine out and don't expect to. If they are not right on the ground, I don't fly. I do not have any sort of on board glow drive system.

One last note: I always tie this beauty to something that won't move with a length of soft synthetic rope before starting the engines. It's looped around the tail and fuse and is a big safety item.






Attached Thumbnails Click image for larger version

Name:	Nl28658.jpg
Views:	38
Size:	143.0 KB
ID:	1626372   Click image for larger version

Name:	Kf13062.jpg
Views:	39
Size:	75.0 KB
ID:	1626373   Click image for larger version

Name:	Lr39528.jpg
Views:	36
Size:	41.8 KB
ID:	1626374   Click image for larger version

Name:	Cw63090.jpg
Views:	38
Size:	125.0 KB
ID:	1626375   Click image for larger version

Name:	Ug53112.jpg
Views:	37
Size:	115.8 KB
ID:	1626376   Click image for larger version

Name:	Ri70078.jpg
Views:	37
Size:	133.6 KB
ID:	1626377   Click image for larger version

Name:	Xz52724.jpg
Views:	36
Size:	118.3 KB
ID:	1626378   Click image for larger version

Name:	Ki30218.jpg
Views:	27
Size:	112.9 KB
ID:	1626379  

Click image for larger version

Name:	Fd62007.jpg
Views:	33
Size:	121.4 KB
ID:	1626380   Click image for larger version

Name:	Er79166.jpg
Views:	38
Size:	139.1 KB
ID:	1626381  
Old 06-22-2011, 06:44 PM
  #2870  
Speedracer2112
Senior Member
 
Speedracer2112's Avatar
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 542
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)


ORIGINAL: Thomas B

Hey, gang...still seeking a source for a top turret. Damaged mine badly on the ground recently and Tower just extended the backorder guesstimate another month, till late July.

Sure wish they would do a better job on keeping parts in stock for their customers that spend significant money on a large ARF. Being out of needed parts for 3-4 months is really not good customer service.

If anyoe has any leads whatsoever for a top turret in stock somwhere or spare to their needs, please PM me.

One good thing about being down for this part is that I am taking time to install the working upper turret kit! However, cannot go any further until I get the clear turret.
I have one. I ship real slow. I should be home by the end of the month. PM your address.

SR
Old 06-23-2011, 06:25 AM
  #2871  
RCGuy41
Senior Member
 
Join Date: Nov 2005
Location: Lusby, MD
Posts: 486
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Welcome Jyjkoz,

You are going to find building the TF B-25 a challenge to say the least. I have had my B-25 for three year's and she is flying great today. Invest into gear that you can afford, I myself don't have deep pockets but did spring for the retracks so I could keep my bird clean in flight. Out of all the guy's flying this bird, my engines are the smallest 2 OS AX 46 2S engines turning two APC 11X8 two bladed props. Both engines have been mechanically synched using a tach, with that being said at idle my engines are running at 2400 RPM and at full power getting approximately 10500 RPM.

Servo's I'm using, standard Futaba 3004's on my flaps and ailerons to include nose steering, rudder's have Hitec MG82's, I forget what's on my elevator and engines. For my onboard battery I'm using a single 6v 2700 Mhr Ni-cad battery, flying on a Spread Specktum DX 7 radio system. Yes before you evan start building your bird, find a machine shop where they can cut some cam levers for you, chunk those ply pieces of qrap after words.

I would also recommend asking plenty of questions, I personnaly have installed a GY401 gyro and am using it for my takeoffs and landings. As usual it's up to the individual builder if there's a piece of equipment they need, so, weigh your optoins carefully and we will provide any assistance you may need and trust me you will get plenty of information and personal opinions, make the best decisions for yourself and what you can afford.

Again welcome, enjoy your build, please keep us posted on your progress with some pics.
Old 06-28-2011, 04:33 PM
  #2872  
Jyjkoz
Member
My Feedback: (1)
 
Join Date: Feb 2010
Location: Port St Lucie, FL
Posts: 84
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Thank you all very much...I have never been so welcomed to a forum....So Far I will be going w/ retracts..still not sure of motors, has anyone used the new small gas engines yet?..Not sure of servos yet .What cam levers are you referring to? The gear doors....I will be soon devoting plenty of time building and this is one of my first projects
Old 06-29-2011, 05:15 PM
  #2873  
Thomas B
My Feedback: (4)
 
Join Date: Jul 2002
Location: Fort Worth, TX
Posts: 1,257
Likes: 0
Received 1 Like on 1 Post
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

A huge thank you to Speedracer2112!!

A good chance to also say thank you to to all the great guys on this forum, as well. I damaged my B-25 during a ground handling accident (my own fault) and was able to get the parts needed to fix it, except for the top turret.

Tower was letting me down, with that part on back order for about 3 months, based on the latest date published. REALLY frustrating. I expect them to extend the backorder yet again, based on past performance.

Speedracer was incredibly kind and helpful and worked things out for me to be able to get my model repaired using a spare upper turret that he had. Now I do not have to wait yet another month.

Am taking this time to install the motorized upper turret kit, since I was down anyway.



Old 06-29-2011, 08:42 PM
  #2874  
Weeso
Junior Member
 
Join Date: May 2009
Location: Beirut, LEBANON
Posts: 9
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hi all
I watched and read this entire helpful forum silently and used all the suggested tips to build my baby, I used 91 magnum 4st engines (I used the 91 size due to the high altitude our club is at 1300 meters above sea level) last Saturday was my test flight I was shaking and nervous although I knew it was easy to handle, I didn’t use the retract because one of the air cylinders was out of order I had to do my maiden flight without retracting the gear.
Simply the flight and landing were awesome, but my friend who was filming the flight got nervous and couldn’t complete until landing, I will post it later, but I will post the pics were taken by another club member.
Our club’s site: www.amazrc.com
Thanks to all who made building this baby easier.
Attached Thumbnails Click image for larger version

Name:	Ec88384.jpg
Views:	36
Size:	69.5 KB
ID:	1629584   Click image for larger version

Name:	Xs57353.jpg
Views:	45
Size:	49.3 KB
ID:	1629585  
Old 06-30-2011, 01:38 AM
  #2875  
gregory.aldrich1
My Feedback: (9)
 
Join Date: Oct 2008
Location: Brandywine, MD
Posts: 82
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Very cool Weeso, glad to hear it went off without a hitch.


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.