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

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

Old 01-31-2011, 05:39 AM
  #2726  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Very good points Brad. I have decided to switch to "cool power" for the reasons you wrote about. I have experienced some of the problems you wrote about as well. Because of them, I now store all my aircraft indoors and keep them climate controlled. Just curious, what percent nitro do you run in your B-25? I bought gallons of 10% cool power to break in the multiple engines I am installing in aircreft this year. I will most likely stick with 10% for the non-performance birds but I was wondering if I will get what I need for the twin Saito 82's in the mitchell. I'm sure breaking them in with 10% is fine, but wonder if switching to 15% for actual flying would be best. What's your choice?
Also, appreciate the notes on the RF editors. I had 3.5 and remember them, but never actually tweaked any craft. But I am looking to make the default Mitchell included with the expansion pack into a more realistic rendition of our B-25 birds. I'm thinking of adding weight, a gyro, duplicating the Saito 82 performance if possible and simulating one engine out senarios. There may be other things as well, but I haven't got the Tower shipment yet which has the sim. When I get it and can get started on the adjustments, I might be asking you for some help. Hope that's okay. Have a good one, Greg
Old 01-31-2011, 07:02 AM
  #2727  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hi Greg,

Since I'm flying the smallest engines recommended by TF (OS 462S) for the B-25, I'm using Coolpower 15% for the added power. I have noticed a few guy's using 30% fuels, not a good idea, my reason; aircraft engines are designed to be light but strong with good cooling qualities not unless it's cowled then we have to provide good cooling. When using 30% nitro in an engine designed for 15% or less you generated more heat at point of ignition creating greater pressure in turn putting more stress on the cylinder head and retaining screws. Helo engines are designed with that idea, greater heat and pressure to turn massive rotor blades to include a cooling system that puts ours to shame. As for a 4S engine use the same fuel for brake-in (10%) as you would for flight but use a smaller prop during brake-in, IE. brake-in with a 11-8 and fly with a 12-6. You may loose some RPM but you will have a more reliable running engine over time, as usual any choice of fuels is up to you, all I can do is provide advice the final decision is up to you my friend. If you can find coolpower (10-15%), buy it, I know that GPA hobbies in crofton stocks it.

I'm going to start getting back into my RF 3.5 and work on some of my saved planes, should be interesting to see what I can make.
Old 01-31-2011, 08:39 PM
  #2728  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

I took my B-25 to the field on both Sat and Sunday. About ten flights total. I just love this plane....and she loves me too. I have OS82a's with 13x7 APC's and retracts on Cool Power 15%. She is just wicked fast. I had the guys at the field egging me on to do things that are not exactly "scale". Inverted flight, hammer heads, deliberate death spirals, loops, rolls, stalls and hovering. I even induced a flat spin that freeked me out a bit.

On Real flight. It is pretty close to what you can do with a plane that is set up perfect and is "over powered". Thats the trick, it has to be perfect. As most of you know my first B-25 went in on her maiden flight. I tried to fly her like others had recommended and not like she should be. I had no expos and was scared to death. It was a bad combo.

She will do anything I ask her to do and the only rules my plane has are the following.

1. Nose down at all times at low speed. I can have the flaps and gear down with the motors at idle as long as I have the nose pitched down with out fear. Keep your speed up during level flight.

2. Never jerk her elevator even at high speeds unless you like death spirals.

3. Land on the mains! Three points touch downs will bend your nose pin.

Thats about it. Shes a tough bird for sure.


I dont know how you guys are getting your plane all oily? Mine stays very clean and a paper towel per nacelle is about it for clean up. And trust me, she is spotless before she hangers up for the day.

SR
Old 02-01-2011, 05:32 AM
  #2729  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg,

Okay, I got into my RF 3.5 last night, you can setup for on-ground and in-flight emergencies, the program determines when the situation happens. You can edit any aircraft that has been installed in RF and then save it. The B-25 in expansion pack 4 is a 1/6 scale; it has 110" wings and OS 90 4s engines, all can be edited, scaled down to TF B-25 demensions.

SR,

Sir you are putting your B-25 through it's paces and it's still going strong, even with an engine out, death spiral save; are you saying #2 is leading a charmed life no matter how you fly her. Tell us the truth, it's your confidence in the model and your piloting skills that have wow'd everybody at your field. By the way saw the pics of your ASM B-17, great plane, so how does she fly? Do you have in-flight video posted yet?
Old 02-01-2011, 12:09 PM
  #2730  
Bill Giulian
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

SR. Working on my B-25 and am installing OS82a's. Could you please tell me how you installed the mufflers. Did you use some type of extension and is so what? Bill.[8D][8D]
Old 02-01-2011, 04:58 PM
  #2731  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey Bill, Greg here. Don't wish to speak out of turn or answer someone elses question, but I am using Saito 82b's and I think there isn't much difference between the A's and B's except for a different size case. I think the exhaust port is generally in the same place. What I did is use a 90 degree adapter along with the original pipe, then into a straight muffler used for the Saito 65's. I had the same setup on a Saito 100 in a Super Skybolt and it actually added a little power and sounded awesome. Now, I can't neccessarily recommend the 90 degree fitting because it is actually designed for application of a flex pipe. Of course I found this out after the fact and am hoping I wont experience any major problems because of it. But, if you used the 90 adapter and a flex pipe with a bracket attached to the nacelle structure just outside of the cowl, you would be within what Saito recommends. I am going to use the mufflers because I already bought them and they are installed. I will sure up the installation with a bracket or two when I am back inside the nacelles again while installing the glow drivers. Not sure if it helps, but thought since I am using a very similar engine, you might want to get my ideas as well. If you go back a few pages, I have some photos posted of the under cowl install.
Take care, Gerg
Old 02-01-2011, 05:38 PM
  #2732  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)



ORIGINAL: RCGuy41

SR,

Sir you are putting your B-25 through it's paces and it's still going strong, even with an engine out, death spiral save; are you saying #2 is leading a charmed life no matter how you fly her. Tell us the truth, it's your confidence in the model and your piloting skills that have wow'd everybody at your field.
Its the plane. Thank Tim "Krproton" and his team for that. The only plane that performs better than this one is the Top Flite Cessna 182 ARF. The lack of fear has driven the rest. I need to post a video of her. Ill work on that on the next nice day at the field and post it here so that everyone can see what she can do. Is she charmed? YES! Would you believe she doesnt have a scratch on her? Not one. Keep in mind I do maintain her to very strict standards and do regular teardowns, inspections and repairs to keep her perfect.

ORIGINAL: RCGuy41

By the way saw the pics of your ASM B-17, great plane, so how does she fly? Do you have in-flight video posted yet?
She is presently disassembled and undergoing extreme weathering. (see photos of wing) She has never flown. I took her to the field for "show and tell". I never take a large plane to the field and fly her on the first trip. She wont fly for a few more trips. It allows all of the guys to get over the shock of seeing her. I did the same with my B-25. It takes the stress off the whole process.

Most of her build can be found here.
[link=http://www.rcuniverse.com/forum/fb.asp?m=10071562]ASM B-17[/link]

ORIGINAL: Bill Giulian

SR.

Working on my B-25 and am installing OS82a's. Could you please tell me how you installed the mufflers. Did you use some type of extension and is so what?

Bill.
Bill I didnt like the new style of mufflers so I ordered the old OS 72 mufflers and installed those. You can see them in the photo. Its a big photo so zoom in on it and you can see them.

SR
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Old 02-19-2011, 05:53 PM
  #2733  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg here. Decided to buy a large trainer and break in the Saito 82's in flight, on a trainer. Feel a little better knowing I've got them dialed in just right before I finish the install into the bomber.
Old 02-21-2011, 10:11 AM
  #2734  
djstar39
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Sounds like a good plan Greg. I did my on a stand and wow was it a goopy mess. Might as well get some flying done while burning that fuel!

dave
Old 02-21-2011, 01:56 PM
  #2735  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Yeah Dave, it wasn't like I didn't get a big mess as well. Although yes, flying the fuel up was more enjoyable than watching it go up in smoke on the bench. I actually did burn 40 minutes worth of fuel before heading to the field with the first engine. Another 30 minutes worth of flying and viola! One Saito ready for install. Just finished mounting number two and should get that one done before the weekend is over. Then, some painting on the inside of the nacelles and cowls and it's back to the build. Had to back up and re-group because I decided to go with Normand's suggestion of the onboard glow drivers which will be mounted inside the fiberglass nacelle structure. Figured as long as I was starting from scratch, again, might as well go ahead and paint the inside of the nacelles and wood structure. That saves me the time later on. Still looking for a maiden before march is out, fingers crossed.
By the way, I went ahead and mounted the three blade 12X8 prop after breaking in with the 14X8 two blade, for the initial flights. I wanted to check RPM's and tune for the three blade props ahead of time. I used Morgan "Cool Power" 10 percent and was getting a steady 9500 RPM's at peak lean setting on the bench. Came back to 9150 to 9200 on the bench which should give me around 9400 in the air. So, the cool power 10% seems to be enough to get the RPM's. Just thought I would let everyone who was interested know. For those of you who may not know, I am mounting the Saito 82b with a planned permanent prop size of 12X8 in three blade cofiguration. Although I did, and am breaking in the engines with a 14X8 two blade prop. Both props are Master Airscrew brand.
Old 02-28-2011, 05:06 AM
  #2736  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Okay, first the good news. Both Saito's have been run in with 40 minutes of bench running and 30 minutes of in flight time on the trainer I bought for that purpose. Of course when I was done breaking in the Saito's, I then mounted an O.S. 91 Surpass on the trainer for it's permanent powerhouse. Haven't flown it with the 91, but I'm guessing I'll have plenty of power, but that is another thread.
Spent a portion of yesterday, Sunday the 27th almost completing the painting of the gear bays/nacelle structures and the interior parts of the crew stations. Absolutely could not stand the bright greeen of the stock paint job and went with a royal air force interior green instead. Knee pad for nose gunner repainted to a decent leather color as well. Now, building can begin again with everything in order. Will mount the dual glow drivers in their respective nacelle structures for each engine and gear bays are now painted to look more realistic. That will be the extent of the scaling for now. Object is to get it in the air this season and get to know her. Next winter will be for the weathering/rivets and panel lines and of course the bomb bay installation. Ran out of time and most importantly money! Somehow, I have to go back now and find the stretch of posts on gyro installation and positioning. Totally forgot what the setup recommendations were that Normand posted. I have never installed a gyro and this is bound to be a challenge. Plus, I've got two 4200 mAh, 6 volt batteries, two JR Match boxes to install and configure and all this has to be mounted behind the cockpit somehow. Not really looking forward to this part of the install. I did buy some foam wire keeps to try and make it all organized and less of a speghetti mess. I have time off this week, so my intentions are to hit this build hard and see how far I can make it by the weekend. Essentially, I have only finished the inner wing panels by I would say 60 percent. Both flaps, cowls, dummies and final plumbing will have to be completed before they are ready for mounting onto the fuse. Seems a daunting task at this point, but I realize I just need to dive in and start working. The "parts pile" will begin to deminish and the plane will begin to start taking shape. This is just such a huge project. The biggest I have ever taken on. Look for more pics and posts in the following days on what I will finish.
Now, the not so great news. Weeks ago, I said I was going to be receiving my new RF 5.5 and was looking forward to hooking up my own radio to the software to use with the Top Flite B-25 that was included. Well, I misunderstood the web page and thought when they said 1-5 "Add ons" were included, that meant I would be getting the bomber in #4. Wrong! What I need is "Expansion Pack 4" not "Add on" #4. Okay, my mistake. So, ordered expansion packs 4 and 5 through tower and expect them to arrive on thursday. This morning, I mapped and calibrated my 9303 to the software and am now ready to use this radio to practice with the B25 when it arrives. I have to tweak the default craft in the expansion pack to mirror it as closely as possible to the actual bird on my kitchen table which is looking like it is going to be a little harder than I imagined. I think you may have to be an engineer to easily understand the "edit aircraft" screens, but I will attempt to learn how. That is the not so bad, bad news. The really bad news is this. Once I reconfigure the default B25 with my own adjustments, including channel mapping and such, the aircraft cannot be "exported". The software denies the user that function because of the radio configuration. But, what I can do is, once the airframe is adjusted to as closely as possible to the real model, I can export that one into the swap pages and and pass that one on to other users. At that point, any user can import the adjusted version of the Mitchell and use the Interlink controller, or configure they're own controller themselves. The purpose of all of this is to develope the aircraft in real flite to mirror the actual model as closely as possible, and to use my own controller, with switches and knobs all designated, so I can get used to what switches to use and not have confusion between the interlink and 9303 when I actually make it out to the field and maiden this beast. So, I'll keep all posted on what progress I am making on the mitchell once I get the expansion pack and begin to "tweak" the default Mitchell. I know there was interest from several guys on here to get that reconfigured version once it was done so I'll do the best I can to fix her up so she acts like the real thing would. Of course, I would need someone who has allot of stick time to confirm that the computer model is in fact close to real feeling. The issue with that is all older designs are forward compatable with RF 5.5, but designs made on 5.5 are not compatable with older versions of Real Flight. So, anybody wishing to import the re-designed mitchell for use on they're own RF will have to have at least the version of Real Flight that is compatable with the expansion packs. It's all very complicated and although I am computer literate, I am not an IT guy and certainly not a rocket scientist. Anyway, I have praddled on long enough.
To Normand, any helpful hints on gyro installation would be greatly appreciated. Afterall, your the one who convinced me to get one! LOL
Old 02-28-2011, 05:25 PM
  #2737  
ronbell
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg, Thanks for the update, it sounds like you are making great progress and will indeed be flying in the spring. I know that you will get the best guidance from Normand regarding the gyro but thought I'd send you the following few tid bits in case they help...

First, I have attached a couple of pictures of the accessory mounts that I have installed. The large air tank install is obvious. The wood plates on each side of the fuselage are for the bomb release controller (starboard side) and the matchboxes and channel expanders (port side). Those items will be installed to the plates using velcro. The plywood plate epoxied to the top of the fuse (pictures are taken from the bottom, looking up) is the mount for the gyro. It has scrap pieces packing underneath with the whole lot epoxied to the stringers and bulhead former to create a solid, horizontal platform. The gyro is mounted to this platform using the double sided gyro mounting tape that I use on my helicopter gyros. However, 2 or 3 layer of the good quality 3M double sided tape from Home Depot (the stuff with the red backing) would work fine. The tape is needed to isolate the gyro from the majority of the vibration transmitted through the structure - you do not want to hard mount the gyro.

I believe you said that you are using a Futaba 401. I also use that gyro on one of my helis - please take note that for the gyro to initialize properly it MUST be powered up in Heading Hold mode (gain more than 51%) but you should NOT try to fly in HH mode or disaster is likely. Therefore, part of your start up sequence needs to be allowing the gyro to initialize in HH (steady red light) then switching over to Rate mode (gain less than 49%) before doing anything else. Also, you should have a mechanism set such that you can't accidentally select HH in flight. I don't mean to scare you but this is very important. I had a friend lose a new aircraft on first take off due to a control surface 'hard over' from his gyro being in HH mode (he had his gain values reversed). The easy way to tell which mode you are in is to apply a rudder input then release the stick - If the rudder stays deflected you are in HH mode, if it centers like you would expect you are in rate mode.

Also attached are some pictures of my completed bomb bay (finally!!). Now I get to open the manual and actually start building the plane!

Ron.

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Old 02-28-2011, 08:16 PM
  #2738  
RCGuy41
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey Gregory,

Sounds as if you are off on the right foot with your build. As for the gyro it will be tie'd in with your rudder servo's with the sensativity line pluged into the aux channel (2 postion) selected for a gyro. As for sensativity you'll need to get into your radio and set it at approximately 75% on high AVCS for the GY401, the low side should average approximately 10% or less. Ronbell is correct, upon take off switch your gyro from AVCS to your low rate, with AVCS on and trying to turn with rudders the gyro is going to fight the turn because the gyro wants to go strait. On another note, the GY401 gyro has two seperate settings for the type of servo your running, on most helo's they are running a digital, we on the other hand don't need a digital so we us two analog servo's so the gyro needs selecting to analog, with the gyro set in digital will actualy burn up a analog servo because the gyro is sending out a more powerful signal that a analog servo can't handle. As for where to mount your gyro, some will say to mount it at the center of the aircraft at the intersection of the longitudinal and lateral axis, the line from the center of the fuse and the line between the wing tips, where these two lines intersect that's where your gyro should be mounted. I have mounted my gyro just under the removable flight deck and my gyro works just fine, do your own research and determine where you will mount your gyro. On your 9303 select a empty two position toggle that won't get bumped while flying your bird. I'm getting ready for the upcoming flying season and have one nem bird to maiden and others ready to get back into the air.
Old 02-28-2011, 08:59 PM
  #2739  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Ron you're making so much of a nice job with the bomb bay, I built mine in october 2007 and back then those accessories were not available and mine was just out of the first batch of production as I ordered it 5 minutes after the announcement in july 2007.

Feels like you're making the latest release, the""full equipped" version of the plane. Tthis is certainely exciting, I might just get back to the working table and modify mine for a bomb bay...and I thought then that adding brakes and and a gyro would be it!

Congrats on your work and guys like you, Greg, Brad, Dave, SR, Rc Guy and those I missed really keep the excitement with the B-25

Cant wait to fly!

Normand
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Old 03-01-2011, 04:32 AM
  #2740  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Hey guys, I haven't gotten into the fuse yet, but after I finish the tail feathers and wing tips with the ironing and servo installations, there isn't anything else for me to do except get into the nose gear and electronics install. The wing sections containing the engine pods are still getting painted so they will be later in the week. I haven't read the directions on the gyro yet so I don't know what they say, but I'm getting from you guys that there is a switchable lead to the reciever to enable switching from the transmitter. Unfortunately, I recall that I had no free channels at this point. Any suggestions on how to use a different aaproach, either coupling with another channel or will the gyro stay in low sensy mode without a switchable channel? Not sure how to go about this.
Greg
Old 03-01-2011, 05:13 AM
  #2741  
RCGuy41
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Ronbell,

Very nice work, I like the lay out, everything is nice and neat. Maybe one day I'll have the funds to purchase a 10x system and add a bomb bay into my B-25. Again very nice work, and when you finally get her airborn the B-25 is a sweet heart to fly.
Old 03-01-2011, 10:40 AM
  #2742  
ronbell
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Thanks for the kind comments guys. To be fair, I do have the advantage of doing the bomb bay first so I am not trying to modify a 20lb aircraft that is already crammed with stuff. Having said that I have learned a lot along the way and made several minor changes to the Wingspan design that could be helpful to others embarking on the addition of the bomb bay system. Feel free to contact me if you want my take on the strengths and weaknesses of the stock mod kit.

Greg - for the gyro you will need a Rx channel assigned to gyro gain control. I am implementing that by combining the rudders and nose steering servos via a matchbox - the Rx rudder channel feeds the gyro input, the gyro output feeds the matchbox, and the matchbox feeds the 3 servos for rudder and steering. The Rx channel that would have been used for nose steering is then available for gyro gain control. In addition to the matchbox taking care of servo reversing (if needed) and matching of the rudder servos it also removes the issue of whether your servos are compatible with the gyro. However, if, like me, you are using all digital servos then that is a non issue anyway. The downside to this approach is that it means that steering trim has to be set up via the matchbox and steering range will be mostly determined by the mechanical set-up of the steering servo arm. This is because, from the bench testing I have done,the ATV adjustment range of the matchbox appears to be quite limited. I am planning to use the smallest arm I have on the steering servo as I keep hearing that less is more for steering on this aircraft, especially when flying from asphalt.

Ron.
Old 03-01-2011, 08:20 PM
  #2743  
djstar39
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

I have my gyro / rudder / nose wheel wiring set up just like Ron's. However, I put it on the Aux 2 three position switch above the right stick on my 9503. This allows me to select HH for initialization, rate mode, and fully off. Doesn't have to be this way but this is how mine ended up. Really need a checklist to remember all of these start up procedures because taking off in HH would be really interesting as soon as you started to turn! [:@] Not being in HH mode when you flip your receiver on for initialization probably wouldn't be good either.

That Bomb bay is looking awesome... and familiar!

One thing I have to do this Winter is order another set of machine guns. Have managed to break off both tail, the nose, and one side gun. JB welded them back a couple times but it's time for a new set. Usually break when someone is helping me flip it over to clean it or get to the bomb bay or whatever. Have to be more careful this season!
Old 03-01-2011, 09:53 PM
  #2744  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Okay, question for Brad, Ron and Dave. First off, I used one matchbox for trimming the flaps. I will simply mechanically adjust each wings flaps to as close as possible and then use the matchbox to adjust each wing seperately. Now that leaves me a matchbox (ordered a twin pack) to use after the gyro. My plan is to use the matchbox exactly as ron stated. RX to gyro, gyro to matchbox and then onto the servos. The only difference will be I will only run a single line to the back and match the rudder servos mechanically, like the flap servos in each wing. Now, I understand the concept of the matchbox and how I can fine tune the nose gear to taxi straight seperately from adjusting the trim on the rudders. That will come in handy once the maiden is done and I may have had to trim the rudder in flight. That will change the nose steering and I can counteract that by adjusting the matchbox only and get the nose wheel back to center without affecting my trim adjustment on the rudders. That is all great and I love the technology we have at our disposal these days. I'm all good with that. Here's my problem. I have no freaking idea what I am doing with this gyro and after tinkering with it for two hours, I think I finally got it to switch from one gain to another but I have no idea what gain I should be at.
I, like Dave have the gain switching on the three position switch above my right stick. I am using a JR XP9303. I have enabled the gyro mode and I can adjust. I've figured that much out anyway. I also have the gyro switches in the right place. Digital switched off because I am using HS82MG's. Reversing switch is in right position because the surfaces and nose gear are turing in the right direction. My problem is this, without any experience with gyros, I don't know what to set the "delay" at and I don't know what to set the values at on the gyro system screen on the TX. Could someone tell me what those values should be? I understand that the HH mode has to be on while powering up for the gyro to set itself. After that, I guess the second position should be for flight. What would the third position be for, to turn the thing off all together? I have been pulling my hair out way too long already. I need help! Thanks, Greg
Old 03-02-2011, 04:55 AM
  #2745  
djstar39
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Ron,

I'm using the 9503 with the Gyro on the Aux2 switch. You should be able to see Gyro when you press the List button. If not, let me know as I think you'll have to do something in the Device Select section.

Scroll over to the Gyro Sys. in the List and press the roller bar. Mine looks like this:

[Gyro Sys.] CEN 0: 50%
Aux2: AX2 SW 1: 85%
STICK INH 2: 0%

This means when the switch is fully forward (position 0), the gyro is off (50%).

When the switch is in the middle (position 1), the gyro is in HH. Anything greater than 50 is heading hold. Anything less than 50 is rate. 50 is off

When the switch is in the bottom (position 2), the gyro is in rate. I'm actually going to change this setting a bit greather than 0 to play with my sensitivity in Rate mode. I don't have the instructions for the 401 gyro with me. Can someone tell me in rate mode how to make it more sensitive? Is closer to 50 more sensitive?

You can change the numbers for each switch position to whatever makes sense to you. You might make the bottom position 50% which would be Gyro off.

Greg, let me know if this helps.
Old 03-02-2011, 05:08 AM
  #2746  
gregory.aldrich1
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Thanks, what you have written makes sense and it was the conclusion I was coming to after hours of playing with it. So, when is the time to use a "heading hold" setting? I'm thinking no time right? Except for when your powering up I guess. What I was also looking for was some logic about the values. I mean, you have a value of 85% for heading hold and 0% for rate. Why not 65% and 35% respectively? Plus, do you use the GY401 by Futaba and if so, what do you have your "delay" dial set to? Thanks, Greg
Old 03-02-2011, 05:21 AM
  #2747  
djstar39
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

It is the 401 gyro from Futaba. The delay is zero I believe. The only time I've heard of some guys using HH for airplanes is on takeoff to keep it absolutely straight down the runway. Upon wheels up, you would switch to rate before any turning is attempted.

Not sure how I ended up at 85 and zero. The rate mode doesn't seem as sensitive as I would like it so I want to change the zero value. Just can't remember if closer to 50 is more sensitive or closer to zero.
Old 03-02-2011, 05:55 AM
  #2748  
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg - since my gyro experience is from helicopter applications I'll leave the other guys to provide recommeded gain settings for flight. I plan to intially set my gain to one of the side sliders on my 9303 until I find the setting that I like and then move that over to the regular gyro gain function in the TX. However, there are many ways to skin that cat and it really comes down to personnal preference and whatever you are comfortable working with. However, here are a few pointers about the gyro that might be helpful...

1. Like you I was initially planning to use a y-harness to combine the 2 rudder servos. Nothing wrong with that. I simply decided when running the wires through the plastic tube to the tail that I might as well run 3 instead of two, just in case mechanical matching of the rudders became tricky. This is definitely in the nice to have category and might well prove completely unecessary.
2. If you use the matchbox between the gyro and the servos then the gyro is not talking directly to the servos so the digital/analog setting is not important from the standpoint of damaging the servos. That setting controls 2 things... First, it changes the format of the signal from the gyro and the digital setting would burn up an analog servo if it was connected directly. Second, when set to analog it allows you to adjust the response time of the gyro to compensate for the fact that analog servos can't respond as quickly. In effect it lets you tell the gyro to wait a little to let the servo catch up. This is the purpose of the delay setting. However, having said that, this is really for helicopter applications where you are trying to lock the tail rotor response for a solid hover. For airplanes, using the matchbox approach, I would set the gyro for digital servos, set the delay to zero and forget about it.
3. The gain setting stuff is hard to explain until you get your head around the connection between ATV values, gyro gain values, TX gyro programming values, and the heading hold vs. rate mode settings. The first thing to understand is that a normal radio channel puts out a signal with an ATV range that is nominally -100% to +100%. In the gyro function in the 9303 that becomes a gyro SETTING of 0 to 100%. Hence 0% = -100% ATV and 100% = 100% ATV. It's really worth drawing a scale on a piece of paper to keep this straight!! Now when we start taling in GYROGAIN then there are TWO ranges; one for heading hold mode, and one for Rate (sometines called Normal) mode. EACH GAIN has a range from 0 to 100% with 0 being 'gyro switched off' and 100% being maximum gyro control. Let's take each in turn:

- Heading Hold (AVCS) mode - ATV values of +1 to +100% apply here, which equates to gyro function setting values of 51% to 100%, which equates to gyro HH GAIN values of 0 to 100%.

- Rate mode - ATV values of -100%to -1%apply here, which equates to gyro function setting values of 0% to 49%, which equates to gyro HH GAIN values of 100% to 0. NOTE that as the ATV/ setting value DECREASES the gyro gain INCREASES.

NOTE 2 things - The signal range goes from 100% gyro gain in rate mode (at the lower extreme) to 100% gyro gain in HH mode (at the upper extreme). NEVER send a gain control signal that is exactly mid-range (0 ATV) as the gyro will be unstable due to not being able to determine which mode it should be in.

A reasonable starting point for gyro gain settings is usually 50% gain ( -50% ATV or 25% gyro function setting) but you do want to always have a way to quickly turn the gyro to 0 gain (off) - if the gyro gain is too low then no harm will be done, but if it is too high then you might experience yaw ocscillations (rapid tail wagging).

4. Another thing to check before any attempt is made to fly is that you have the gyro DIRECTION set correctly. THIS IS VERY IMPORTANT. With everything powered up and the gyro in RATE mode (amount of gain doesn't matter) then first verify that the rudders respond properly to you stick inputs; right stick = right rudder and vice versa If they don't then you need to reverse the rudder channel in your Tx. Now, with the stick centered, turn the aircraft (or just the gyro) in the yaw axis and verify that the gyro moves the rudders to counteract the turning motion - if you turn the aircraft such that the nose turns to the right thaen the gyro should inject left rudder. If it goes the wrong way then you need to flip the DIRECTION switch ONTHEGYRO, not in the Tx.

5. Last thing I can think of right now is the range pot on the gyro. This control how far the rudder servos can physically move. Normally you control sevo range using the ATV settings in your Tx. When using a gyro things are done differently... You should set the rudder channel ATV values to +/-100% and leave them there for now. Next, again with the gyro in rate mode, you use the range pot on the gyro to adjust the the servo range such that maximum stick input gives the desired maximum rudder deflection with no binding in either direction. When using a gyro the ATV values in the transmitter really control the response speed of the rudder more than they do the actual rudder value. Hence, lowering the ATV would 'soften' the rudder response feel and higher values would make things more 'twitchy'. You can play with these values later if you don't like how things feel in flight.

I hope the above helps - it took me a while to get my head around the who gyro thing when I first got into helicopters so don't feel special in any way. Ask lots of questions until you are comfortable that you have things straight.

Ron.


Old 03-02-2011, 06:01 AM
  #2749  
RCGuy41
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Greg,

On your GY401, leave the DS switch in "off", the DIR switch put it in rev the reason, when a right eng goes out the plane yaws to the left on the good eng. You want the rudders to counter that yaw to keep the plane flying strait. As for the delay and limit I left mine as they sat from the factory and I have had no problems from it. Greg you only need a two position switch for your bird, AVCS (Heading hold) used for taking off and landing, after gear up and before my first turn the gyro gets turned off. If there is an inflight emergency my switch is just above my right index finger. I'm flying my B-25 with a DX7 spread spektrum system and my pre-flight concists of the following; battery volt check (plane & TX), install both outer wings, fuel, air, check TX all switches in normal (for me all up), power up the TX, power up the plane (do not touch for 10 seconds, gyro sync) the gyro sets its self to AVCS (HH) check with rudder input the gyro fights the input, then turn off gyro and check free movement of rudders, and finaly perform a range check.

Greg as for your nose gear steering, after my maiden flight my steering wasn't the greatest with that said I trimmed the rudders in-flight, after landing I had to manualy change the steering linkage to compensate that wasn't very hard, just a few turns at the turn buckels connected to the nose wheel steering servo. Any further questions please feel free to ask.
Old 03-02-2011, 06:19 AM
  #2750  
djstar39
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Default RE: Top Flite B-25 ARF (Tecnical, tips, suggestions)

Something else to think about... when you're lined up on the runway and you advance the throttles, if both engines don't spool up together in the same RPM range, you're likely to have this bird wander all over the runway from one engine pulling stronger than the other as you advance from idle to full throttle. Normally what follows is a lot of rudder input (usually over correcting if you're me) to keep her straight.

Taking off in HH mode will help to keep this straight. I have brakes on mine so I line up, hit the brakes, run both engines up to full power, and then release the brakes. Always straight and true and I usually take off in rate mode which helps a little if you have a gusty cross wind.

I believe if you take off in HH mode that you have to be careful NOT to touch the rudders when advancing the throttle. I believe (could be wrong) that entering any rudder inputs on takeoff would change the rudder neutral position and the gyro is going to try to correct. Ron, is that right?

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