norm

Joel,

for magnets check out this site: http://www.duramag.com/neodymium.htm...FRNOagodSwcKXg

Choose as strong as you whant for the magnets and small...1/4 inch to 3/8 size disk.

Also the twin engine glow driver is located in the bulkhead behind the cokpit. I used a 2700mah 4.8 v NiMH battery to power it. dont worry about weight mine is now 23 lbs and still fly great. The wire need to be 40 inch on both sides due to the central position of the glow driver unit itself.

Look at the pic the glow dr unit is on the left and battery on the right.

Normand

djstar39

My Feedback: (4)

Norman,

I just started this project and I'm going to duplicate your setup engine wise using the Saito 82's, VP30 Perry Pumps, and straight exhaust pipes. Question: What motor mounts did you use? They look metal in your pictures. I would prefer them to the ones that came in the kit. Also, 4-40 bolts for the engine mount and the mount to the firewall seem small to me. Will probably go with 6-32.

You mounted your engies at 6:00 but mentioned later that if you had to do it over you would consider 12:00. I have the choice now but not sure if I want the cylinder heads sticking out the top.

Also, I have the MCD Twin glow driver but also have two MCD466's and saw that in hindsight, you might have gone with them in the nacelles vs the twin. Do you still feel this way? I love the 466's in my other warbirds.

Thanks! This thread has been awesome! It's a long read but well worth it! Not sure I'm all that creative but I imitate what works for others very well! Will be using the 401 gyro as I have a lot of experience with them from my heli days.

I also would like to get a set of metal levers for the gear doors. I believe Mike-RC was doing these. Mike do you have any left?

Thanks again!

Dave

norm

Hello Dave,

The engine mounts are H9 mount link below. Iused those for the narrow mount to the firewall.

http://www.horizonhobby.com/Products...?ProdID=HAN40M

I would still mount the engines (82's) right side up since you only see the valve covers.

Rebuilding it I wouls also go with a digfferent engines as mentionned in the first few pages...the Saito 100 flat twin:

http://www.horizonhobby.com/Products...rodID=SAIE100T

also you should seriously consider reviewing this site:

http://www.rcdon.com/html/top_flite_...ell_proje.html


the engine mounts are offset a little to enablle the crankshaft to pierce out in the center of the cowl due to the angle in the firewall. Your prop once installed will look as if it is pitching down and turning away from the fuse on both sides...this is normal. You find the center from the template in your instruction book use those, do not photocopy since it may change the form then draw the center from the H9 engine mount and rotate to your liking.

On the mount the two front holes attach to the two front holes on the engine. The two back holes of the engine need to be drilled on the mount. You then insert a flat washer #6 size to shim for the difference in height from the mount between the front holes and the engine; you will understand when doing this.

Good luck Dave


Normand

RCGuy41

Joel,

Rare earth magnets are a way to go; my ADF antenna on the bottom uses four magnets, two in tne antenna and two in the aircraft. You should have the same setup in your kit. Joel, if you have an electronics store even Radio Shack they normally stock rare earth magnets; plus you can get them in various sizes and strengths.

Brad

RCGuy41

elojim,

Hi, some of us are on a budget and I myself can't afford digital sero's. In my B-25J I have put HS-322HD on the throttles, elevator, and nose wheel steering. Ailerons and all flaps I have installed Futaba S3004, rudder has two HS-85MG, and mini futaba servo for gear retract. The majority of servo's today will work off of 4.8V - 6V systems. With a 6V system your servo's will provide better once inch of torque http://www.futaba-rc.com/servos/servos.html this link will answer all your questions on futaba's line of servo's and once inch torque they put out at 4.8V and 6V, here is Hitec's link http://www.hitecrcd.com/servos/show?name=HS-322HD In the end it's all up to the modeler who's using the desired product for their aircraft.

Brad

djstar39

My Feedback: (4)

Thanks Norman! I had looked at the motor mounts on HH but passed by this because it said '40 size'. I now understand that 40 size is referring to 2 stroke so I'll order a couple of these. I'm assuming you used the 4 stroke template in the manual vs the 2 stroke.

Would love to go with Saito 100 twins but I already have the 82's and budget won't allow me to spend another $1000 for this bird. :-)

The RCDon site is awesome and I've already reviewed it (printed a bunch of it out). Thanks for the tip!!!

I'm sure I'll have more questions as I progress through this build so I hope you all don't mind the questions! Will probably take me all winter because I have a 3 year old and a 9 month old and very little time to steal away to play with my 'toys'. :-)

Dave

norm

1000$ is a shame I know but like Brad mentionned we must keep in touch with reality and fix some monetary limits...it is easy to get carried away.

You have the best engine anyway for this project, the 82's are very powerful with a 1.5hp rating you will spin the 12 x 8 3 blade MAS at 9800 rpm, power to weight ratio is the best with the 82's.

Now why I mentionned to install the engine right side up 1200, (twelve o'clock) is because you will avoid "syphoning" effect of the carb positionned lower than the tank center position if installed @ 0600 (six o'clock). Once started it has no effect on the engine. On the ground you must fill and start immediately to avoid leaking 1/4 of the already little amount of fuel...the 82's are powerful but thirsty.

I knew this before but went ahead with the 0600 position anyways...just because I wanted the muffler pipe to stick out where it is &^%$#.

Good luck and keep us posted

Normand Ouellette

jdhughen

My Feedback: (1)

Dave,

IF you go with the 12:00 mounting and still wanted the pipe out the bottom you can get the flex pipe (12mm) for that engine (SAI65111) from Horizon.

Norman,

Should a by-pass arrangement be used with any pump setup (v20's in my case) or just the v30's ? I got a lot of flak on the "twin" forum about using pumps. several suggest adding a nipple and using muffler pressure (the KISS phylosiphy). I could do that but I'm conderned about leaning out as the tank gets empty (and the fuel contamination build up). what kind of run times are you getting from the 82's from the supplied Tank ?? I'm using 72's which should be similar, If I can get a decent flight time and keep 1/3-1/4 tank I might consider adding the nipple and leaving the pumps out.

BTW I converted the all RCdon B-25 web pages to a single self-linked PDF if anyone wants a copy. Handy if your using any of it as a guide and are away from your connection. I tried to post if here but system won't except a PDF.

Joel

norm

Joel,

I want the pdf copy.

For the pump set up it is better to have the bypass. Now I have concerns of why would anyone think it is better to add muffler pressure to the pump??? this is not at all desired since the pump is intended to maintain a constant and steady pressure.

The whole idea of a pump is to eliminate the muffler pressure!!!! I heard that before Wow There are a lots of "engineers" in this hobby... It is better to stick with the Conley Precision "Perry Pump" recommendations you. You will also avoid fuel contamination.

As for myself I would not use the VP 20 but the VP30, but the system is the same. For some reason the non harmonized vibration of 2 engines with the VP20 oscillating pump make me wonder. Keep me posted on the results.

As for the bypass make the return "T" as close as possible to the inlet of the carburator.

With the 72's almost the same size as the 82's (+/- 1mm), you should get 8-9 minutes run time and remain with approx 1/4 tank enabling you for 3 missed approach.

Normand

elojim

Hi all,

thanks for your answers about the servos. It's a pleasure to post on this forum !!

My choice :
throttle HS-82MG
elevator HS5645MG
flaps HS5245MG
ailerons HS5625MG
rudders HS-82MG
nose HS625MG
gear HS-82MG

jdhughen

My Feedback: (1)

Norman,

The "Twin" folks were not suggesting I use muffler pressure in additon to the pumps....they were suggesting I add a nipple to my straight pipes and use muffler presure INSTEAD of pumps. While I understand the value and wisdom of the KISS philosiphy, Based on my exp with saitos running lean at the end of the tank under muffler pressure I think the use of pumps is justified ??? With the bypass loop, even if a pump fails the engine can still draw form the tank. I think the idea with this arrangement of pump/bypass is to keep fuel presented to the carb for it to draw on not nessarily a constant positive fuel pressure on the carb inlet ?? is that correct ??

Has anyone out there using saitos without pumps had any problems with engine leaning out toward the end of the tank ??

Joel

djstar39

My Feedback: (4)

Joel,

Thanks for the tip. What is the length of the flex pipe? Would love a copy of the PDF as well.

Thanks!

Dave

jdhughen

My Feedback: (1)

The flex section is 6" , including the elbow it's 7".

I tried sending the pdf to norman and it's too big for e-mail, 37mb. does anyone know if there is a place on this forum where I could up load it ?

Joel

mtaboram

Hi Normand:

I flew my B-25 last weekend. Was amazing. I will post a video soonest. The plane fly wonderful, very stable. I´m so happy[. We had an International fun Fly in my Club and I won the first place using this plane.

In my first flight I have some problems with the gyro. Reading the forum I think the problem was the gain. I will try this weekend again.

Attach you could find the link of my first flight. [link]http://www.youtube.com/watch?v=C2Bs8v-o-BY[/link]

I had some problems with one of my engines ( I never got the same RPM (+/- 200-300). I had to use a Y harness to conect both Thro´s servos, because I couldn´t mix them using individual channels. Could you help me with this situation?. When I use a separate channels for Thro servos the Digital trim of my Tx (JR9303) control only the master channel? how may I control the slave channel?

Other problem that I had, was the Glow drivers. I´m using the Mcdaniel 466 but I never got a good functionallity for them. I don´t know if was the charge of them or what. I had to use the traditional NICAD glow driver to start the engines.

One more issue.Originally I used a Hitec Digital Mini servos HS-5245MG for the Throthles but both servos was literally burned. I don´t know what happend. Fortunally I identified this situation on ground. I´m using a duralite regulator on 6V, Lithium Manganese Batteries (3000 mah 2s2p). Do you have some comments.

I really appreciate your comments.

Regards

Marlon

RCGuy41

Marlon,

A very nice video of your maiden flight, congratulations. I'm going to provide some answers to some of your questions.

1. What type of gyro do you have installed? I have a Futaba 401 w/none digitals on the tail, I had set the gyro DS setting "off" reversed the throw then set the sensativity to "0" on the gyro itself. With your radio X9303 AUX2 and 3 are used for sensativity input to the gyro, Flavio recommended the high point "AVCS ON" between 70% - 75%, low or "OFF" 0% - 1%.

2. Since I know very little about JR radio systems, I would recommend that you read over page A-16 of your owners manual, it covers Twin Engine. (Wing Type.) If you don't have a manual here's a link http://www.jrradios.com/ProdInfo/Fil...Res_Manual.pdf you will be able to download and print as your copy.

3. I fly two McDaniel glow drivers on two different aircraft, A. make sure your drive is grounded to the engine body normally between the mount bolt and engine mount tab. B. check your reversing switch on the driver housing by turning your radio on then your aircraft (if your battery is charged your red LED should come on at low throttle settings.) As you advance your throttle (on the TX) the LED light should turn off at approximately 1/3 throttle. C. if your glow driver is new; normal charge (first time) is approximately 10 to 12 hour's. D. make sure your quick disconnect between the driver and engine is red to red and black to black, if your LED light is coming on at high throttle settings then reverse the glow driver (there's a switch on the driver.) E. Lastly, set your TX throttle to 1/3 (aircraft is on) and adjust your glow driver "on" / "off" setting there's a small reostat that sences throttle position. F. make sure both engines are grounded, i.e. red wire to engine body and black to glow plug.

4. About the only thing I can think of why your throttle servos burned up; may have been your servo's were reversed and with linkage connected and system on they were fighting against the linkages trying to get to their set points. If your power spiked throughout a 6V system you would have had more items to replace, i.e. receiver, battery, leads, and other servo's.

Just my two cents worth, hopefully this will help, I know Norman will provide some guidance, he's very experienced and provides sound advice.

Brad

mtaboram

Brad:

Many thanks for your comments. I will consider it and I will let you know the results.

Best regards

marlon

jbarnes

On the 9303 go into I believe its wing type and thats where you "slave" the channels together. I don't have my radio in front of me but you access the slave feature on the initial setup menu where you label the model etc. You can then use the throttle sync feature of the 9303 to fine tune your adjustments.

toreo

Best video B25 from flyingcam

http://www.rcuvideos.com/video/Best-...from-flyingcam

djstar39

My Feedback: (4)

Normand (or anyone else),

I'm at the point of positioning my Saito 82's and I now see what you mean about mounting at 12:00 vs 6:00. I know there is a general rule about mounting the engine / fuel tank such that the spray bar of the carb is not lower than the fuel tank... is that the center of the fuel tank or the center of the fuel tank opening. Since the stock fuel tank openings are offset this could be a big difference. As I hold my engine in place at the 6:00 position, the carb would be about an inch lower than the middle of the fuel tank opening. I think this is what you were referring to on the siphoning effect. Even if the general rule is the middle of the fuel tank the carb would be lower but not as much.

I will probably go with the 12:00 mounting and seriously consider the flex pipe so that the exhaust isn't coming out so high on the cowl.

One other question Normand.... as I hold up the engine mount in what I think would be the centered position such that the prop shaft comes out properly, it would appear that the top right bolt hole (on the left engine) will be right where the horizontal piece of wood is on the other side of the firewall. I can see that they scooped out a half moon piece on the onc side and was wondering if you did the same on the top right side. If you didn't encounter this, I might have to go back and remeasure as we're using the same engines and mounts (I picked up the ones you suggested in an earlier post from HH).

Thanks!!!!

Dave

norm

Dave,

for the engine mount , I had the same situation you have . I simply drilled and installed #8 1.25 inch metal screw for the 2 top holes on the engine mount. The engine mount is offset a little to the inside (fuselage side) and you need to sand off a little from the wood mount of the nacelle in order to be in the middle of the cowl.

I mounted the bottom with normal # 6 machine screws and blind nuts and the top with metal screws are soaked in epoxy along with the whole firewall. I just "sunked" the engine mount in there in order to avoid vibration. Make certain also to screw the # 8 screws then remove them and soak the wood with CA and let it dry before installing the screws with epoxy to reinforce the screw area.

Mounting the engine @ 06:00 is OK but the tank will syphon and cause the carb to leak when not operating the engines. I think it is just a little more reliable to mount the engines at 12:00 and avoid all this.

Also in my opinion it really does'nt matter where the exhaust come out! The breather nipple and the exhaust will spray the plane with so much oil that you will feel like a chrismass dishwashing party after a day flying there is a lot to clean! In fact i beleive it changes the CG considerably! you need to wipe some off at times!!!

Normand

asnook

Flights 6, 7 and 8 on a full size runway in England.

CCFPILOT

Congrats on 8 successful flights. Looks like a great place to fly. Nice pictures.

camdyson

Well done asnook - that first shot is a ripper.

There's a fly-in at the local RAAF (active) base this weekend, so I hope to get mine certified and (fiiiiinaly!)test flown if the weather is suitable. 2000m of runway should help to calm the nerves Unlike the UK, we don't have old WWII bases everywhere, so getting to fly from there will be a real buzz.

Only job left is to balance on the "Vanessa" tonight (have you guys needed any lead? - how about lateral balance?), weigh her, then load her up in the trailer which is finally in the driveway at home.

I plan to start with the CG at 5" as recommended with wheels down, unless anyone has found a better spot (I'm using Robart wheels with tyre inserts, so heavier than the foamies).

Cheers,

Cam

cobi.p

hello to you all

the box from TF have arrived to my house and all i can say is WOWW .
i have RCV 91 CD for the SWEET and soon ( i hope ) it will fly in israel .

cobi

CCFPILOT

Great, now in 100 hours or so, you'll be ready to fly. Good luck with your new TF B25.