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norm 05-18-2010 09:02 AM

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


ORIGINAL: Speedracer2112

The B-17 is '' wood and carbon fiber frame covered in an ABS molded shell''. per the artical. My local hobby shop has ordered two of them. I want to see one first.

200+ flight in a year......southern Florida baby!! Flying 24/7/360 I love it!

SR
Yeah seeing it first is a wise decision. Too bad they make such a nice plane , like a nice designer suit, Armani or Boss, cut in paper, the plastic crack like egg shell.

Well enough with this other subject and I apologise to slip into this discussion here.

This is a TF B-25 site and I certainely agree with you SR a long take-off and gentle lift is gracious.

Normand


Speedracer2112 05-24-2010 06:59 PM

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


ORIGINAL: Speedracer2112

I have run across another problem to report or at least to think about as you build. Its the fuel tanks. Easy enough right? Well after a year of flights and a little wear my right tank is sucking air when I de-fuel. I have holes in my lines!! The tanks are literally burried in the nacells. To rework them means removal of everything down to the wood core of the nacelle and cutting them out. I have to do this now or pay for it when I loose a fuel line or lean out and overheat. I admit that after 200 flights this should be done anyway to check the tanks for wear, but geeze its a big job. Anyway, I will begin tearing her down next weekend. I may be able to fix this with just the removal of the motors and mounts working from the front of the firewall. We will see. I will make a post after I am done to discuss the stress damage of 200+ flights within the nacelles if I have to tear them down. I can easily see this rock solid plane making several hundred more flights easily with proper maintenance.

Cheers!!

SR
Hi all,

I did tear down the nacelles this weekend. I found that the tank in question did have a split fuel line. Fortunatly, it was on the fuel/de-fuel line and not to the motor. I tore down both sides in about five hours and replaced all of the fuel lines and clamps. I had used the factory silicone lines and when I pulled on them all but one of the four fractured easily.

I then took her to the field to fly that day. I ran both motor and re-tuned them. About five minutes in the right motor abruptly stopped and smoke billowed from it. I took off the cowl and found one of the lines had popped off. I rechecked everything and restarted. I flew a few times and everything was fine but the motors were out of tune. I hate that! Before the tear down it was perfect! I decided to land to tweek the motors. On touch down the plane landed on the mains and then the nose slammed into the runway. The nose gear was up. *#@$*!. I never noticed it. It took out both props and sanded down my nose canopy during a 100 ft skid. I was so focused on the motors I failed to air up the retracts before take off!! Boy I was bent. I appologized to her profusely, and took her home and repaired her that day. I only hope she doesnt hold it against me.

If you installed the factory lines PLEASE replace them this year. I had to take off to the engine mounts and worked from the front of the fire wall. It will save your plane. Granted I had hundereds of flights, but its just not worth it, not to change them.

Cheers!

SR

Mustang Fever 05-24-2010 07:22 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
You're absolutely right about the fuel tank and line issue, guy. I never use the stuff that comes with ARFs.

M_Callahan 05-30-2010 09:15 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Maiden flighted my 25 today. 2 eight minute flights. 16 minutes of
multi-engine time for the log book!

2 clicks right aileron trim, 1 click down elevator trim. Flies like its on rails.
Flaps slow her down just right for landing.

I guess I'll keep her.

Mike

Mustang Fever 05-30-2010 09:40 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Glad to hear it went well, Mike.

I'm flying mine tomorrow at the annual spring Dawn Patrol at TRAMPS in Traverse City, Mich.

Ran the engines up today and was real pleased with the results. (She'll do about 57 mph and have about 18 pounds total thrust at wide open, not bad for an 18 pound airplane.)

M_Callahan 06-01-2010 07:41 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Thanks Bob. Running OS .70's. One new and one with a season of flying on it. 8 minutes
of flight uses almost all the fuel in the tanks! Still running rich though.

How did you flight go?

Mike

Mustang Fever 06-01-2010 10:04 AM

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

Now I gotta tell the truth. Perfect scale TO, great flight, and then: either the right engine quit when I was turning final, or wind sheer caused a big gust to come up behind me. The guys say engine failure, because every time I went to throttle up a little it started turning, but I couldn't tell which way, as I was way far out trying to get a shallow approach to a difficult runway. Anyway, she sorta pancaked into a fresh plowed field behind some trees. Nose canopy broke. Minor damage to the mating rib on the inboard right wing panel, and two bent wing tubes. Gonna take longer to clean all the dang dirt out than it will to repair it.

I really don't believe it was engine failure, just pilot error. The wind shear has been so bad this spring it is very easy to get into trouble. There were four totals yesterday at that fly in. Basket cases.

Speedracer2112 06-01-2010 10:55 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Sorry about your plane Bob. :( if you need some parts PM me. I have a little bone yard from my first one and a LHS gave me a lot of nacelle parts.

I flew about 10 times this weekend. Two ugly landings after I took a pill for an incomming migraine. The pill took out my migraine and my landing skills at the same time. We had a gusty crosswind and it kept spinning me towards the pitts fences. My last landing made the guy next to me hit the deck. I spun out and saved the plane from the fence by about a foot. Not cool. No more flying with migraine medicine on board. Ill need a new retract nose pin but that's it.

In a club with 200 members only 10-12 people showed to fly each day. Crazy?....

SR

Mustang Fever 06-01-2010 12:16 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Yeah, my club has maybe 15 guys, and there's 3 or 4 who fly. Go figure.

Thanks for the offer on parts, but the damage is really minimal to mine. Unless you have a bombardier canopy you want to sell, because those are on backorder at the moment. I already ordered one and a tube set, which will give me some spares, but I can cancel the canopy if need be.


Speedracer2112 06-01-2010 01:42 PM

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


ORIGINAL: Mustang Fever



Unless you have a bombardier canopy you want to sell, because those are on backorder at the moment.

I do have one. I bought it as an extra. If you get your plane back together before they are in stock LMK.

SR

Mustang Fever 06-01-2010 04:56 PM

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

Tower says end of June, that should be soon enough, but I'll let you know.

M_Callahan 06-01-2010 05:48 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Man that really blows. I hate plowed fields. Always seem to
be coming in across the rows instead of with them. I blame
the farmer, if he would learn how to plow a straight furrow.....

Anyway, hope you don't have to wait very long for your spares
and get her back in the air quickly.

Mike

Mustang Fever 06-01-2010 07:14 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
1 Attachment(s)
You got it, Mike.

I was wearing thongs, and I don't think I'm ever going to get the brown stains off my feet. I'm sure that's why she survived, though, as the landing gear was buried in the dirt and she was resting on the fuse and nacelles when we found her.

Cleanup is literally the most time consuming part of this repair job. The actual damage is almost inconsequential.

My pal did get a got pic of her in the air, albeit at pretty long range.

LargeScale88 06-02-2010 06:29 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Quick question on this B-25. Is the whole fuselage, wing, tail, elevator, is it all sheeted with wood? Cause if I bought this, I would tear the covering off, and fiberglass it, so I need to make sure that it is all sheeted. Thanks

Mustang Fever 06-02-2010 06:42 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
The bird is mostly sheeted, but all the control surfaces and the outboard flap sections are open framework monokoted.

I wouldn't want to hazard a guess at how much one of these things would weigh 'glassed, but I know I wouldn't want to fly it.

LargeScale88 06-02-2010 07:26 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Glassing doesn't add a whole lot of weight ( from my experience). I fiberglassed a sport plane that was 4 pounds, glassed it was 4.8 pounds.

Mustang Fever 06-02-2010 10:07 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
That's almost a 20% increase in weight. The lighter they are, the better they fly. My 25 came in at a little over 18 pounds, and is real easy to handle. I can't imagine flying one that weighs 25 pounds or more, like many of them that have been discussed here.

Mustang Fever 06-13-2010 07:55 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
1 Attachment(s)
After two days cleaning out the dirt and about 2 hours in repairs, the B-25 flew again. I did switch to 11 oz tanks and 12x6 MAS 3 blade props. These give plenty of thrust and speed, and keep the engine revs around 10,000 so fuel efficiency is much higher. During testing, the engines both ran almost 30 minutes before running out of fuel.

I was able to synch the engines to within 50 rpm of each other by carefully shortening the throttle push rod on the faster engine. Both engines are tuned to jump up 200 rpm on a "pinch" test, which is where the 55AXs run best.

I still can't get over how easily this airplane handles. It's my first glow twin, and I'd recommended it as a first twin to anyone, it's that easy to fly. The only real differences between this scale bird and sport planes are:
1. On takeoff, after getting to full throttle, just put in a little up elevator and hold it. She'll fly off when she's ready in a lovely scale manner. I use flaps on TO to reduce the ground run.
2. Do the landing downwind and crosswind legs at half and about 1/3 throttle, respectively, with flaps down. Anything less than that and you'll get too slow for safety. This bird has a lot of drag and slows down quickly without power. I reduce to a 3000 rpm idle after having settled onto final near the threshold. Then, just let her slow down in a level attitude as she sinks toward the runway, and get the nose up gently just before touchdown.

c550 06-13-2010 09:39 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Largescale88,

I stripped the monokote off of the fuse and glassed it. I also added a cockpit and bomb bay doors. The weight is no problem for this bird as long as you don't go too overboard. I couldn't see building a bomber that doesn't drop bombs.

Regards,

Dave

Mustang Fever 06-13-2010 09:47 AM

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

Did you get that bomb bay door kit that I've heard about, or do your own design? That's one scale feature that would be a hoot.

c550 06-13-2010 09:47 PM

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

I just made it myself. much earlier in this thread some people posted the dimensions. I basically used that except there is a former about a 1/4 inch from the scale location. I used that as the forward location. I mounted 4 vortac bomb releases in a light ply plate that mounts in the bomb bay. Its pretty cool. I hinged the bomb pay with piano hinges from Nelsons. I basically used some of the ideas from this thread and simplified it a little. It adds to the cool factor. Here is a link to a video of it flying: http://www.rcuvideos.com/video/Top-f...nverted-to-a-U

Regards,

Dave

Mustang Fever 06-14-2010 08:44 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Thanks, Dave. Great video.

I went back through and found the pix and info that Tim provided.

Once I get real comfortable flying this animal, I'll consider doing the bomb bay.

djstar39 06-27-2010 07:27 AM

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

I finally managed to break the Robart nose gear off at the pin this weekend. I was using the rubber grommet but the pin gave way. The nose gear door hinges also parted way during the slide on the grass at the end of my landing.

What are you folks doing for extra axle pins? Do you buy them directly from Robarts? From Tower Hobbies? Make your own?

Have any of you had to replace the spring hinges in the nose door? Did you drill out the existing ones or start over next to them? Also, where can I buy the hinges? They come as part of the gear door assembly but that's $42.00. Surely I can buy these spring hinges separately.

Thanks for your help!

djstar

Edited:
Norman / Krproton, it looks like you had a solution for the broken spring hinges on the nose gear door around posts 596 and 597 on page 24. Did this end up your final solution? Thx!

Speedracer2112 06-27-2010 08:58 AM

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


ORIGINAL: djstar39

Hey folks,
I was using the rubber grommet but the pin gave way.
Rubber Grommet? I didnt know there was one. Sounds like a great idea, where can I get one?



ORIGINAL: djstar39
What are you folks doing for extra axle pins? Do you buy them directly from Robarts? From Tower Hobbies? Make your own?
You can call Robart and they will ship them to you. They are about $6 each. They are the mains axel cut off so you can get those also and cut them yourself.



ORIGINAL: djstar39
Have any of you had to replace the spring hinges in the nose door? Did you drill out the existing ones or start over next to them? Also, where can I buy the hinges?
You should be able to grab them with some needle nose plyers and twist them out. I have a set somewhere. If you want them you can have them.

SR

djstar39 06-27-2010 09:45 AM

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

The rubber grommet is Normand's idea (I think). Post 1356 on page 55 has pictures. I got mine from Menards here in Indiana but I'm sure you can get them at Lowes or your local hardware store.

I'll give Robarts a call on Monday. Somewhere else in the thread I know they were heat treating them so I may have to give that a shot. I'm conflicted because I fly off grass (long take off rolls) and I think I would rather have this pin break than something more substantial.

Not sure I'll be able to twist them out as I think they're epoxied in there. Will give it my best shot though!

Thanks for the offer on the hinges! I'm PM you.

djstar


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