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

SR:

I had the low speed versus high speed trim problem also, before I weighted the right wing tip. I'm curious how- much weight did you use, and what size are your engines?

I gave up mixing throttle with anything a long time ago, as it only seems to work if you open the throttle very slowly and allow the air speed to catch up. If you don't, the amount of mix is always wrong, and nasty control issues surface.

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

SR,

After reading over your trim problems, this is just a rcommendation which you have already looked at, but have you trimmed both engines RPM at idle and max RPM? Before each flight I check low and high RPM and adjust both engines high speed needle to within 200 RPM on each engine, in flight I get the same left roll but only have to add six clicks of R aileron trim to adjust and she's flying strait and level. As for landing and taking off I do use my Futaba gyro slaved into the rudder channel to assist at veried speed transition, basically helps counter the effects of torque at low speeds. Just my two cents worth.

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

Bradley: That's a good tip. I forgot to mention that on the few flights where my engines weren't perfectly synched, the airplane had a definite crab.

Lots of "twin" guys say never use the needle valves to synch, but I do it routinely. It's just necessary to insure that one has at least a 100 rpm "bump" on a pinch test with each engine at full throttle.

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

I have my engines matched at all four quads within 100 rpm's. They are OS 81 Alpha's and are pretty much perfect. The issue is very small but is more of a curiosity to me. Sems a lot of people notice it after they get over the initial freek out stage of learning to fly her.

I tried the same 2.2 ounces. I didnt want to try more. I really want to try the rudder throttle mix. I was going to do it in the AM but now I need to work the whole weekend.

SR

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

SR: You might want to increase your weight before doing any mixing.

.81 times 2 = 1.6 oz per engine, or 3.2 oz. It made such a dramatic difference on mine, I'm sure it would work for you. I only used 2.2 because I have a pair of 55s.

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

I have 4 strokes, you have 2 stroke. They have the same power almost. What do you think?

SR

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

I dunno. More is better, right? :D

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

Bob, SR,

Okay, yesterday I retrieved my right outter wing panel to add the recommended weight to counter the engine weight. Well after pulling the aileron servo to my surprise I had already added 4 ounces of lead and I still had to add six clicks of right aileron to fly wings level. Okay, its just an idea I have been toying with but check the outter wing incedence both right and left sides, if everything checks good, the next step is to check that each rudduer is square or 90 degrees to the elevator. The idea is if one or both outter wing panel incedence is off it could cause SR's roll same go's for the rudders. Any other ideas would be appreciated. Just putting in some more of my two cent's.

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

Received my B-25 on Tuesday and now have a good 18 or 19 hours of work in it :) First mistake I've made When mounting the nylon control horns I was not intelligent enough to realize that the screw did not go all the way through and accidentally drilled clear through the control surface. What's the best way to repair the hole? I tried to just run the iron over it in hopes that something magical would happen... but it didn't close fully. From my past experiences, patches never look good because they're raised above the normal surface and often noticeable.

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

mechcanicalfailures,

Normally you would use a small piece of olive drab monocote, but not all manufacturers colors are the same, try going to your local HS and buy a small strip of Top Flite olive drab monocote. Right now you have one of two options, 1. cut the entire area where the damage is then cut out and size a new piece to fit just over each rib, 2. cut a smaller piece of monocote and place over the damaged area and heat with an iron. These are just a few recommendations, also try to find the guy who manufactured the aluminum main gear door bell crank, the lite ply bell cranks will hold up for maybe 5 to 10 flights; I purchased an aluminum set over two years ago and have no idea if the gentalman who built them still sells them. Buy the way the aluminum bell cranks have held up and worth the money; I believe 10 bucks.

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

When you start work on the fuse you will have several big pieces of monokote you need to cut out for the gun packs etc. Assuming its a close match, you can use one of those for your patch so you dont have to buy a whole roll.

David

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

Yep, good observation David[sm=wink_smile.gif]
Normand

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

I bought them and lost them before I could install them. I hate getting old! I never found them.

SR

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

Great thanks I'll be working on the fuselage this week and use the extra. Thanks for the suggestion, I'll go back through and look for him. I haven't looked around much lately, but does anyone have any suggestions to make the cockpit more scale? Or where to find some nice pre-painted pilots?

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

The man who made them is "MIKE-RC" http://www.rcuniverse.com/community/...=1&memid=93152 . Very nice fellow and I'm certain he will be helpful. If you cannot get them I can make you a set sometime in the fall.

Normand

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

Sent him a pm a few days ago. If he's unable to make them I'll contact you, thanks!

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

From what I saw on his profile, the last post was over 2 years ago. Hope he is still active

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

Gutaaaooo,

Dont jumt to conclusion too fast!!! he was on the site a few weeks ago!

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

I hope you'r right, i didn't mean to sound so negative, it was just a observation. Sorry! :P

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

It's been a week or two since I've pmed Mike and haven't gotten a response yet. I'll wait a few more weeks to make sure. Normand, I believe I have a very similar setup to yours Saito .82's at 6 o'clock to eventually be straight piped and pumped. I tried to start mine today with the normal mufflers and got nothing. Primed, got a kick that didnt last, and back to nothing. The cycle repeated multiple times for both engines. I don't have a whole lot of experience with glow engines (and have never mounted one at 6 o'clock), and was wondering if you or anyone else has any suggestions?

Also, has anyone else had problems with the kit supplied yellows prop nuts? Mine simply catch the shaft before fully tightening the props, even with extra washers. Maybe even more washers would do the trick...

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

mechanicalfailures

What engines are you using? Also it is very important to read the full instruction book before you even crank to start a new engine and particularely if you are unfamiliar with it. I know of a site where the fellow; " Brenton Watkins" , I presume is compiling some information for the benifit of all and has put it together in a remarquable presentation; His work is dedicated to saito engines but the same science applys to all engines.
http://saito-engines.info/index.html there is a " new engine prep" tab that explains very well on how to set and break in new engines

Thanks to him, you will find some very interesting information on how to break in engines and maintain them.

As for the 6 o'çlock myth, my opinion is that once the engine is running it really does not make a difference what the cylinder position is...as long as it is feeded correctly. The main problem often overlooked, is the carb position relatively to the tank. When the tank is higher than the carb, there is a syphon effect that enable the tank to leak fuel by gravitation through the carb. There is multiple ways to solve that problem and one of them is using a regulating pump. you will find information supplied by Conley Precision the makers of the "perry pump", here is a link to their installation instruction: http://www.perrypumps.com/Pump%20and...s%20System.pdf .

You will find these instructions interesting and hopefully this will help answer some of your questioning on setting up your engines and avoid "Mechanicalfailure"!

For the prop nut, I suggest you change those for " Harry higley" http://www.harryhigley.com/EngineAccessories1.htm prop nut and safety lock nuts made to the thread of your crankshaft since the one supplied is made to fit the OS engine thread. I would not add washers since those will increase the risk of those propnuts to loosen up and....

Hope this will be of help to you, keep us posted,

Normand

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

Just thought I would post some pictures of my baby girl
She has a couple OS .81a pumped, they are spinning masters 12x8 3p
at just below 10k rpm or so does the twinsinc tells me.
I did the door sequencig mod from rcdon at www.rcdon.com, and it's just beutiful with the LADO retracts working
(got a vid of this here: http://www.youtube.com/watch?v=ZBXcyFXj18Q )

I also did the front gunner mount removable with a couple of rails and magnets, as well as the main canopy. this gives me easey acess to turn on/off and change bateries
the rear gunner I used a dowel to atach the front to the fuselage, and then with the gun/bolts in the back I don't need any more screws.
Botom line, the fuse has ZERO screws showing. the only screws you can see are the ones that hold the iner/outer wings in place, and even so I'll cover 4 out of the 5, because that is all i need to disasemble to transport her. She makes me proud! LOL

EDIT the RCU picture uploader does not want to load. Pictures will have to come in later

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

Thanks for the info and great links I'll grab a new set of prop nuts this week. I'm using saito .82's. I've previously set up and run a Saito 100 and 180, so I'm not completely new to them. My carb is below the tank and I have not yet installed the pump. Even though it's gravity fed I'm not getting any visible leaks until I prime it or it kicks. According to Brenton Walkins, if your engine "...does not back-fire and yet still does not start it probably means you have no fuel in the engine or the fuel line is empty..." however I know i have plenty of fuel (possibly too much?) in the engines. Could this gravity and pressure fed set up prevent the engine from starting and would a pump solve it?

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

Hi all,

I started to build this airplane two years ago et il'd like to thank all the people on this forum who helped me a lot.
I added llanding lights and gear sequencing doors (RCDON). Wheels from Glennis with brakes (very usefull !).
I m using 2 OS 70 Surpass. It's a little bit heavy but the flight is very realistic !

here is a photo taken last week-end.

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

hey elojim, great looking bird!

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