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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)

norm 01-02-2010 10:54 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Sorry to hear that Dave, did you have a gyro? Same thing happened to me in may 2008 and I managed to fly on one engine around and land. Make shure to review the joining at the fuselage. As of now still working on my Lancaster... http://www.rcuniverse.com/forum/m_80...tm.htm#8051097 lots of pleasure dust and all... We have a full foot of snow here by now, the B-25 is hanging there until next season.

Happy new year and I wish your model gets back on track soon.

Normand

Speedracer2112 01-03-2010 11:24 AM

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


ORIGINAL: normandouellette

Did you have a gyro? Same thing happened to me in may 2008 and I managed to fly on one engine around and land.

Normand

I love to know how to install and set up a gyro. Any advise?

SR

norm 01-03-2010 01:35 PM

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

Review the first part of the begining first 20 pages, every thing is described in my postings,

Regards

Normand

Speedracer2112 01-06-2010 09:19 PM

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


ORIGINAL: normandouellette

SR,

Review the first part of the begining first 20 pages, every thing is described in my postings,

Regards

Normand

No.....its not. you wasted my time. All you had to do is say you didnt want to help.

Thanks

SR

RCGuy41 01-06-2010 10:00 PM

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

Normand (Normand posting first and flying with a gyro) and I have posted some great tips to help any modeler upgrade their bird with a gyro to protect their investment. Now the first question, what radio are you using? Next, what gryo are you willing to purchase (I have a futaba 401 can set sensativity, direction, analog, and digital servo's)? The gyro will need to be placed at the vertical access, basically the center of the fuse. The gyro will need to be Y'd into each rudder servo then the remaining lines go into the receiver rudder channel then into an aux channel for gyro sensativity. Your transmitter will have to be programed for your gyro sensativity high at approximately 75 to 80% and the low at 0 to 1%. Any questions ask or PM me.

norm 01-07-2010 08:45 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
1 Attachment(s)
Dear SR, as I said, on page 16 post # 382 will give you the answer.

Re: Gyro:

1- for your first question, the gyro installed on the rudder will maintain the yaw for you until you override it by using the stick. The perfect example is like if you have someone maintaining a control for you until you take over. the gyro installed for the rudder will maintain the ''Normal or another name for it is the vertical axis this is situated @ the center of gravity where if looking over (or under) the plane the plane would swing from left to right around this axix ex: if you were to nail the plane to the ground through the cokpit you could only move it around this nail clockwise or counterclockwise. this is refered to as the ''Yaw''.

Well yes this gyro will maintain the aircraft on a ground roll as straight as an arrow until take off @ 22lbs you need all the ground speed you can get. the best benifit is that it maintains the aircraft coordinated at all time and you do not have to switch to any other mode, it is overridden automatically when you touch the stick and you can also adjust this sensitivity...read the instructions. I know futaba if you are on futaba makes an excellent one as well.

2- The size of a G500A is speaks for itself on the picture.

3- As far as seperate power for the flaps through the matchbox is almost useless because when you are in flight the flaps will only be used for a short field take off or for landing...do not add weight for nothing. 8 servos are almostnot being used when in flight out of 13, so only 5 are being sollicited, a 4000mah+ battery @ 6.0v is what you whant, will increase torque on the servos as well as a security for 1 cell battery failure. I first was impressed by the number of servos and the power required for this monster but now that I've almost tamed it ( maiden this week -end) it is not necessary to freak out for the number of servos...but have power to spare 4000+

4- Yes you can see the executive sweet on the web just google it.

5- The best question is your # 5: you will never know which engine quit when in flight, for the simple reason that you cannot see unless it happens to you on a low pass @ 50 feet or less and still...you do not try to know which one it is (unless in a full scale!), your natural reaction will be to control with the ailerons the moment you see the airplane turn and roll due to an engine failure. The immediate reaction of the plane in a one engine out is, 1-sudden yaw towards the dead engine 2, the engine still alive creates more lift then the dead engine so that wing will lift vs the dead will drop causing a roll. then the uncontrollable spiral dive. Top flite has designed their B-25 with a divergent offset to both engines. I beleive after seeing this design that this will greatly help to maintain the aircraft. Now you should because of this design maintain the wings level with the ailerons and turn by controlling the rudders and unless your nerves are made out of steel and that you do not listen to your normal reaction of whanting to turn with the ailerons you should get the plane back intact if able to position it for a no power landing.

Unfortunately this scenario must happen when you have altitude...with a gyro on the rudder the rudders will correct the 1st occurence of the yaw and maintain the aircraft coordinated enabling you to use the ailerons to fly the aircraft back at any phases of the flight. In any case you do not whant a dead stick on take off, but a gyro will help you greatly at that time becausre this is when you catch a piece of turf or a bump and lose an engine at rotation time, the gyro will help you at this very moment and I defy anyone to be as quick as the gyro in this instance!

The gyro must be positioned very straight, in the middle ogf the fuselage @ the center of gravity of the weight & balance ie: 5 inch behind the leading edge of the wing like on the picture.



Speedracer2112 01-07-2010 07:22 PM

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


ORIGINAL: RCGuy41

Speedracer,

Normand (Normand posting first and flying with a gyro) and I have posted some great tips to help any modeler upgrade their bird with a gyro to protect their investment. Now the first question, what radio are you using? Next, what gryo are you willing to purchase (I have a futaba 401 can set sensativity, direction, analog, and digital servo's)? The gyro will need to be placed at the vertical access, basically the center of the fuse. The gyro will need to be Y'd into each rudder servo then the remaining lines go into the receiver rudder channel then into an aux channel for gyro sensativity. Your transmitter will have to be programed for your gyro sensativity high at approximately 75 to 80% and the low at 0 to 1%. Any questions ask or PM me.

Hi RCGuy41,

I have a Futaba 14 MZ and can get what ever is the best to use. I only have Futaba analog metal gear servos on the rudders. It seems a little complex and I think I might want to test it on another bird first. I have about 35 flights on my B25 and dont want to loose her by going from great to better. I guess you saw Ive had a brush with death once already with the above left engine failure. I learned a lot on that flight! I really appreciate the help. Tell me which gyro to buy. Ill pick it up and then get back to you. The one you have would make it real easy to follow each other. After we are done I will make an exact post on how to do it.

Thanks again.

SR

RCGuy41 01-08-2010 12:26 AM

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

There's a number of gyro's on the market, the vast majority are very good, all you have to do is decide which one will be best for you. I'm partial to futaba plus I had the gyro in hand so I wasn't out much funds (ten bucks for a "Y" harness.) check out this link, you'll be able to get a brief discription of each gyro futaba offers, http://www.futaba-rc.com/radioaccys/futm0807.html also JR has an excellent line of gyro's for sale. The decission is all your's, the GY401 is a very good gyro and can be selected for analog servo's. Your radio is the beast, a great radio to use, wish I had the funds for one, but oh
well. You should have at least 3 to 4 Aux channels to play with? Give me a holler when you are ready.

jdhughen 01-08-2010 12:52 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
I have a Futaba 401 but was wondering if anybody knows where you can get a gyro that is actualy designed to be used on an airplane.?? I know that futaba had some (350, 351, 352) and you could at one time get them through some Honk Kong venders, (i picked up a 352 a couple years back that i used on a 3d trainer for a while) but never offered them in the US and I think quit making them all together??. And then you can't find the JR 500A anymore (the "A" is an "Airplane" designation). I'm not sure why the industry seems to be overlooking this need in our hobby. Ideas ??.

Also with the 401, has anyone tried using the "heading lock" mode on takeoff? I've heard pros and con about doing this

Joel Hughen

RCGuy41 01-08-2010 08:46 AM

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

I have run into the same problem when I was looking for an aircraft gyro, so after a long discussion at my hobby shop when it was around (now closed), a heli gyro does work in an aircraft using the same principles. You're right, futaba use to make aircraft only gyro's but there where no buyers so futaba discontinued the line. I called Futaba USA (about 2 years ago) and made a few inquires, there simple answer was, "there was very little market for an aircraft gyro" so the product was pulled. Also it has been determined that a heli gyro works well in a fixed wing aircraft.

Yes; I use heading hold on take offs and landings. As for the GY401, in AVCS mode (Heading Hold,) the gyro works to keep the aircraft on a strait line by throwing oppositt rudder to compensate for torque, which you already know. Once airborn, before the first turn a scale pilot will need to turn the gyro off (before the first turn,) reason the gyro is going to sence the change and try to drive the rudder/s back. Now you are fitghting the gyro, servo/s and putting a draw on your battery. The only other time you want AVCS turned on is when you are on final (nose of aircraft pointed at runway), the reason, if you have to go around, the sudden throttle change could kill an engine, and low and slow in a twin spells certin doom for the model, that's what we are trying to prevent. Hope this helps.

norm 01-08-2010 10:39 AM

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

I could'nt word this any better. I own a few G500A, all used in my planes those are from JR. For some reason JR discontinued the airplane gyro for the same reason as Futaba. I tried the GWS gyro for 40$ (in my Seagull Dual Ace ...test bed) and there is not enough signal ie: the gyro does not turn the rudder enough even at max rate. The Futaba 401 or JR or JR770 is in my opinion the best solution but both need to be switched off once safely airborne. The G500A is a simple plug and play and easyly overriden.

I found that mixing about 20%, 22% turning left 17% turning right rudder into the ailerons give a well coordinated turn even with the Gyro on.

In my opinion it is a must to be able to switch off the gyro and disable the mix for any needed reasons since a malfunction may work against you.

Also as far as using the gyro on take off I keep it a secret!!!! makes us look better!!!

Normand

jdhughen 01-08-2010 11:22 AM

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

ORIGINAL: normandouellette

I found that mixing about 20%, 22% turning left 17% turning right rudder into the ailerons give a well coordinated turn even with the Gyro on.

Normand,

I heard of people doing this kind of "coupling" but never really understood how it was suppose to work. I use mixes for flaps/elev, nose gear/rudder, brakes, etc. but When I fly most of my planes and use the rudder in the turn I usually have to add Aileron in the opposite direction to keep the wings from rolling to much, OR if I turn with the ailerons/elevator use a little opposite rudder to keep the nose up. Is the mix your talking about, for an example of turning left, mixing left rudder into left aileron such that with 100% left Aileron you also get 22% left rudder ?? I think I'm missing something cause if I did this manually I think my plane go down.

thanks

BTW, I ment to add that I'm really enjoying the lancaster build. You do really good work, and you experience in this thread especially help me a ton.

Joel

norm 01-08-2010 12:06 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
Thanks for the kind word Joel,

Yes in fact you do have to help the B-25 to turn with the rudders turning with the ailerons. The operation you describe turning the rudder and opposite ailerons works well for WW1 bi or triplane to maintaim level. In the case of the B-25 you turn with the ailerons just like a fighter but you add some rudder to help to coordinate the turn.

ie: with 100% ailerons you slave the rudder action @ appoximately 20% depending on your model habit (and on the throw you normally have on your rudders) you then need to fine tune from flight to flight. The variation depends greatly on your model balance and the engine torque with the prop used and of course the throw of the rudder surface. I balanced mine gear up and 1/4 oz noze heavy. The props are 12 x 8 spinning @ 9600 rpm so the torque is high and forces additional rudder turning left.

More to come on the Lancaster... also, the nut house saved me a place: started the Brian Taylor 81", and a 92" A-26 invader, lots of noise for the coming season, who knows, Top Gun?

Normand

djstar39 01-08-2010 01:13 PM

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

Regarding gyro's... I'm using the Futaba 401 and have it set up on a 3 position switch on my JR9303. This allows me to turn it off, have it in AVCS (heading hold) mode, or normal mode. Agree that you NEVER want it in heading hold mode if you're turning. If you did have it on you would probably end up knife edge. Having it in heading hold for the takeoff roll or for landing once on final is probably ok if you always remember to switch it off or back to normal before a turn. I would think that using the normal mode would pretty much accomplish the same thing depending on conditions.

The one thing I need to check out is that I thought that (in normal mode) once you input rudder commands, the gyro should not react at all. It seems to me the last time I bench tested it I held the rudder over to either side and then yawed the B-25 and the gyro still responded. More checking due on my part probably in the sensitivity area.

BTW, I asked Normand earlier why he would turn it off once airborne. I believe his reply was that the odds of an engine out occuring (except for running out of fuel) while the engine is at half to full power is remote and that it's when you're transitioning from idle to full power or vice versa that you're most at risk... as in the takeoff roll or on final if you have to go around. Makes sense. If you want full protection you could leave it on in normal mode but must use rudder for coordinated turns all of the time... something we should all be doing regardless, right? [8D]

Dave

p.s. It's winter bulding season here so I'm adding the rotating top turrent and bomb bay and release system from Wingspan Models to make this bomber functional!!

RCGuy41 01-08-2010 11:16 PM

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

Thanks for the kind words and agree 100% with your statements. By the way; I have looked in on your Lanc build thread, you are doing a fantastic job. That bird is not modeled too often, glad to see some different airframes being built, if there were an 1/8 to 1/7 scale Wildcat kit available that would be my next bird to build. I do know Jerry Bates plans has a 1/5 scale Wildcat and Robarts has the scale gear for it to include Century jet. Right now I just don't have the deep pockets for that size aircraft. Maybe some day. Keep up the good work on the Lanc, it was a fantastic aircraft that could lift a tremendous bomb load for it's time.


Speedracer2112 01-11-2010 07:57 AM

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

ORIGINAL: RCGuy41

Hey SR,

There's a number of gyro's on the market, the vast majority are very good, all you have to do is decide which one will be best for you. I'm partial to futaba plus I had the gyro in hand so I wasn't out much funds (ten bucks for a ''Y'' harness.) check out this link, you'll be able to get a brief discription of each gyro futaba offers, http://www.futaba-rc.com/radioaccys/futm0807.html also JR has an excellent line of gyro's for sale. The decission is all your's, the GY401 is a very good gyro and can be selected for analog servo's. Your radio is the beast, a great radio to use, wish I had the funds for one, but oh
well. You should have at least 3 to 4 Aux channels to play with? Give me a holler when you are ready.
Thanks RCGuy41,

I dont know at this point. Everybody has had great input, but it seems that a gyro might not be for me. I dont need help tracking in or out of the runway straight and if Im high the glide pattern on the B25 is good enough to get back home even with a violent spin. Ive proven that. : )

It seems like maybe a Twin Sync unit would be another choice. If you loose an engine it takes out the other until you pull both throttles back and then it gives you back the running motor if you have the, shall I say, "manhood" to do so. Powering back up after a failed landing attempt would be the danger zone same as with a gyro. I personally would ditch into the weeds at the end of the runway even if I had a chance of surviving a motor loss and going around at that time. I'll take the minor damage versus the potential total loss. Maybe a Twin Star would be a good test bed for me. Im finishing up a P51 right now and I think I'll do that next just for the experience. I just hate not having my own first hand information.

BTW. How long does it take for the gyro to boot up after you turn it on?

SR

RCGuy41 01-11-2010 08:27 AM

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

I understand your situation and I can't fault you, its a decision we all have to make. Do what you feel is best for you! All any of us are trying to do is provide a recommendation on what works, the rest is up to you.

As for the gyro, prior to radio & receiver being turned on ensure your TX switch for gyro sensativity is set to AVCS, turn the TX on then your aircraft don't touch any thing for 10 seconds, after that you are ready to go. If your gyro sensativity switch is in the wrong position your gyro won't work right and could cause a crash, also the gyro will give a continueous flashing red lite stating system error. The gyro does a system diagnostics and then sets itself into AVCS (solid red lite.)

Which P-51 kit/ARF are you putting together, I have a TFGE 60 F4U-1 Corsair on my building table right now, with a few mods going into her for a better scale look.

Speedracer2112 01-11-2010 10:04 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
I'm putting together the H9 P51 Blue Nose.ARF. Nice kit with lots of problems to repair before you can fly it. I also put in the Saito FG 20 gas that has had some problems. I fiberglassed the inner wings at the landing gear, beefed up the tail wheel and broke in the motor very well. I inly have a few odds and ends to take care of now. I stiil like the kit and the motor. Maiden will be next week!

SR.

Oh ya, I bought the Futaba 14MZ from Tower. They sent me two Radios on accident. I called them up and told them. I thought they were going to die. I sent it back and they gave me a $15 gift card as an honesty award. LOL!

RCGuy41 01-11-2010 01:36 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
The new H-9 P-51 is a very nice bird, and have read a few articles and customer reviews of on it. For the money any one is putting out for the ARF kit there should of been zero problems, but with any new ARF there's bound to be some. It seems as if H-9 didn't take in acount grass and hard landings or else they would have re-inforced each gear mount and other areas of the airframe.

By the way; I have seen the price on the Futaba 14MZ, and it's not cheap. You are a standup guy for returning the other radio, my hat's off to you, at least tower gave you something, it's better then nothing at all, in this economy. Best of luck on her maiden, you'll do good.

I have some work to do on my B-25, about a days worth, to tighten up a few things after last years fling season, plus a minor repair to a stripped out servo.

Speedracer2112 01-11-2010 07:43 PM

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


ORIGINAL: RCGuy41

I have some work to do on my B-25, about a days worth, to tighten up a few things after last years fling season, plus a minor repair to a stripped out servo.

I lost both servos in the rudders due to bumps just in moving to the field and one in the air. I put in metal gears the last time. The stock servos just cant take it well. I have mine grounded for the next couple of weeks until I can go over her with a fine tooth comb.

Ill get back with you when I pick up a Twin Star and a gyro.

Thanks!

SR

Speedracer2112 02-08-2010 04:34 PM

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


ORIGINAL: christophe31

i don't understand why you landing so fast, is that the reason why you have those failure, look at my firts one:

http://www.youtube.com/watch?v=qiOS5Kheorg

and he weighted 9kg with the 2 saito gas,
Hey Cris,

I have a question. How are thoses FG14s working out for you? Have you run them in the cowls yet? Are they running good? Do you have more video?

They are available here in the USA now with a different pickup head. I have a FG-20 in a H9 P51 Blue Nose and have just got it tweeked and running good but still have intermitant problems like spark plugs breaking at the tip. It was a process to get it to run perfect.

I want to put together a gunship and these motors are on the possible list.

Thanks

SR

tom2bell 02-22-2010 11:06 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
here is a video of the b-25 from last summer
http://www.youtube.com/watch?v=fl5a44o6554
tom

christophe31 02-23-2010 03:23 AM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
hi guy's,
unfortunatly, i've loosing my plane at the 5th fly,
loosing one motor and goes down in a spin, but i've order another B25 it flies too great!!!!
about the saito's, they're great , i've change one ignition( in waranty) because one motor can't have the full throttle, a friend of me who have the 20cc had the same issues.
they're very hard to set cause they consume only 8cc /mn, so you need to go very slowly when you setup them.

even that problem , they're great , only one tank for the both motor, nice sound , they startup very easily.

Tom2bell:
nice landing without gear , you must looking at electric gear to replace your air system...you 'll winning weight , place, and secure.

Speedracer2112 02-28-2010 08:04 PM

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

ORIGINAL: christophe31

hi guy's,
unfortunatly, i've loosing my plane at the 5th fly,
loosing one motor and goes down in a spin, but i've order another B25 it flies too great!!!!
about the saito's, they're great , i've change one ignition( in waranty) because one motor can't have the full throttle, a friend of me who have the 20cc had the same issues.
they're very hard to set cause they consume only 8cc /mn, so you need to go very slowly when you setup them.

even that problem , they're great , only one tank for the both motor, nice sound , they startup very easily.


Sorry to hear about your plane. I glad you have another now.

The great thing about this plane is it does glide rather well. If you have any amount of speed you can get to a suitable place to land dead stick. I have practiced this with mine so I can pretty much land any time I loose an engine. I still like to fly alone and the guys at my field are the best around so they dont run motors on the ground or fly while she is up in the air. If I loose a motor I pull all of the power from the other motor completly and dead stick in with complete control. You just have to keep the nose down at all times to avoid a stall. In my opinion this is the best technique. Ive tried flying on one motor twice. Both failed with a spiral. I will take mminor damage over total loss anytime.

My B25 has about 50 flights now and has had 2 death spirals that I managed to save her from. If she spins, allow her to dive straight down to gain speed and do not use the elevator until you have the ailerons back, then ease into the elevator. If you yank it your dead.

I also have had 2 nose gear up landings. Zero damage both times. Full flaps, mains down, touch down just as your about to stall inches off the ground in the grass and hold full up elevator as she looses speed. A cross wind gust almost got me in the photo below. She landed perfectly.

One of the guys shot some great photos of her last time she was up. I'll post them next.

SR

http://i145.photobucket.com/albums/r...IMG_9683-1.jpg

Speedracer2112 02-28-2010 08:55 PM

RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)
 
A few photos.

The full album is here.

http://s145.photobucket.com/albums/r...20Flite%20B25/

SR

http://i145.photobucket.com/albums/r...IMG_9595-2.jpg
http://i145.photobucket.com/albums/r...IMG_9604-1.jpg
http://i145.photobucket.com/albums/r...IMG_9537-1.jpg
http://i145.photobucket.com/albums/r...IMG_9526-1.jpg
http://i145.photobucket.com/albums/r...IMG_9536-1.jpg
http://i145.photobucket.com/albums/r...IMG_9433-1.jpg


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