ronbell

Well done Weeso - many congratulations!!

Ron.

krproton

Very nice Weeso. Many happy landings! (Nice images tooI like the black-and-white!).

Tim

nelcob

Hello.
I have a B-25, a radio futaba 9 cap, I wonder if this radio has the twin function, and how to configure it.
thank you very much.

Mustang Fever

My Feedback: (2)

If you don't have the manual for the 9CAP, you can get it here:

http://manuals.hobbico.com/fut/9c-manual-v1_2.pdf

Pages 58 and 59 cover the use of mixes, so that you can use one channel for each engine's throttle, and then have a switch to turn off one of them for starting purposes. I think you can trim them separately, too, but I didn't read that far.

nelcob

Hello everyone.
I have two engines saito 82 Golden Night, I know how many RPM could square and each engine must have had.
Each engine is giving me 11,000 RPM.
thank you very much.

gregory.aldrich1

My Feedback: (9)

That's pretty good RPM's Nelcob. I am turning 12X8 three blade props with Saito 82b's and max RPM's after richening back is 9240. The bird takes off without much runout and has plenty of scale power in the air.

Greg

nelcob

thank you very much Greg for answering.
But I have a concern.
carburetor engines at 9200RPM, the tune with the needle or digitally.
thank you very much.

gregory.aldrich1

My Feedback: (9)

I use a digital tachometer. I run the neddle in at full throttle to get it to max RPM and then back it off about three hundred RPM's. In the air the motors are likely running at 9400 to 9500. I think I could be getting more RPM's if I were to use two blade props, but the three bladed props are doing fine and I appreciate the scale effect of the three blades.

Greg

nelcob

Thanks Greg.
What about the Gyro. a question?
surface of the plane that should control the Gyro, the ailerons or rudder.
Thank you.
I share some pictures of my plane.

RCGuy41

nelcob,

Hi, your gyro should be wired in line with your rudders. The GY401 will have three sets of leads, 1 for the RX rudder channel, the 2nd is for the leads going to your rudder servo's, 3rd lead goes to your RX aux channel for gyro sensativity.

RCGuy41

Last Sunday Greg Aldrich and I flew out of CCRCC field, here is some video of my flight. http://www.youtube.com/watch?feature...&v=oC6Etk_RYm0

show871

Has anyone tried twin DLE20's in this plane????? Would it work well???

Thanks!

gregory.aldrich1

My Feedback: (9)

He, if I were you and I was thinking about putting gassers into this one, I would be considering the FG14 from Saito which is suposedly the same as the Saito 82b four stroke. The 14's from Saito are four stroke gassers, which I think would sound really cool in this bird. Just my idea.

Greg

elojim

Hi Jyjkoz,

i've finished my B-25 last year with some modifications :
- option to sequencing gear doors witch really add scale (go to rcdon.com)
- landing lights
- wheels with brakes from Glennis (if you're going to add brakes, i suggest to use 2 separate air tanks rather than a larger one)

It's 22 pounds, so a bit to heavy. Realistic fly but needs about 100 meter before take off !

I'm using 2 OS 70 surpass 4 strokes (13x8 two blades - 9000 RPM max) witch are no longer available.
I can suggest you OS 81a or Saito 82

Wings, and flaps : servos are High Torque (i'll tell you witch one when i go back home)
elevator : Hitec 645 MG
rudders, trottle : hitec HS 82 mg

Radio : futaba 12 FG - (I'm using 14 channels - 17 servos)

No gyro, no twinsync.

here's a video : http://www.youtube.com/watch?v=RmzwFAXGxf0 (take off - 3 min flight - landing in slow motion)

air8521

Hi All,

Share with you my B-25 maiden fly two weeks ago.

http://youtu.be/szEN20kLBDE

(Special thanks to RCDon who made fantastic build thread)

Engine powered by 2x Saito FA-100T, Master 3-blade 13x8 prop, 8400 & 8900RPM
Futaba system, 12FG
Servos/channel

Mustang Fever

My Feedback: (2)

Good job, Steven.

You're getting about 67mph and around 9 pounds of thrust apiece from those engines. Perfect choice.

Jyjkoz

My Feedback: (1)

I was thinking about going Gas ...My thought was the same Saito FG14.....My other option is on the other side of the spectrum the Magnum 70 four stroke.....Whats the thoughts out there?

air8521

Glow engine should be the best choice of TF B-25, my opinion~

Due to:
1) Saving Weight: No CDI requirement, on board glow drive will be done a good job for two engines.
2) Reduce Vibration: I built and flew this B-25, many assembly way didn't consider the vibration that gas come with, even 4stroke gas the vibration is bigger than glow one.
3) Beauty of cowl: I had a friend built with FG-14, the cowl chin is almost gone for FG-14 and especially the exhaust pipe need to cut larger cowl for FG-14

FYI.

ronbell

Hi Guys, sorry that I've been out of touch for so long. A lot has happened in the meantime...

First, I got laid off in August. That sucked but did afford me some extra time to get my girl finished. Then I landed a better job in October (my company develops display systems for military aircraft). I maidened the B-25 on Sunday, 10/23, and started my new job the next day, 10/24, which is why It's taken me until now to let you know about my very exciting, near disastrous maiden. Here goes...

I started out intending to do a very careful maiden with no bombs loaded, etc. However, as I had set the aircraft up with a half-load (4 bombs) for a static display the day before, I decided to leave those in there as, should the worst happen and the maiden flight turn out to be her last flight, I really wanted to know if the bomb system worked!!! With a full fuel load that gave me a take off weight right at 25 pounds. I therefore set myself up at one end of our 350ft runway as I knew that my 2 FS-72's were going to have their work cut out. My buddy Damian came with me as he has the H9 B-25 and we both wanted to avoid a repeat of what happened to him; he stalled in the flare about 6ft off the deck and pancaked it (all fixed now, thank goodness). His is much lighter than mine so that was my biggest worry (after getting off the ground and clearing the trees).

The take off run was uneventful although I used the whole runway (partly because I forgot to use any flaps) and climbed gently to build as much airspeed as I could before turning towards the trees. The trees at our field are very partial to eating planes! It took a couple of circuits to get her trimmed. I wasn't expecting to need so much right aileron trim and didn't really appreciate how much had been dialed in until it bit me later as you'll soon hear. The source of the problem was that with my fear of her falling out of the sky I was flying around at about 3/4 throttle so there was lots of engine torque going on!

I got further fooled by the fact that the rudders were WAY too sensitive so I had my hands full in the turn to stop her from doing bad things due to over controlling. Anyway, once I remembered that breathing was still necessary once in a while, I did mange a couple of nice medium altitude passes and did a bomb run - the system worked beautifully with the 4 bombs releasing sequentially 1, 1, 2 with about 1/4 sec between. It looked very cool!!. With all 8 bomb it would be 1, 1, 2, 2, 1, 1. You can see the release of the last 3 of the 4 bombs in one of the stills below but, unfortunately the video resolution is not good enough to see them.

Then came the excitement - landing.... As you'll see in the video, even when I thought I was slowing her down I was still way, way too hot and that got me into all sorts of trouble. Things were made worse by me being at the end of the runway rather than towards the middle where our normal flight stations are. I thought being at the end would help me as she would cross the threshold right in front of me and then I'd have the whole runway with me looking at her from behind. Reality was that it completely messed up my perpective as the viewing angle was very different to what I am accustomed to.

We have power lines running parellel to our runway that can be used as a friend on the approach but also like to mess with your head as we have all discoved at one time or another that those poles will not get out of the way!!! The result was that my first approach was not at all lined up well. As soon as I saw that it was probably not going to end well I throttled up and came uncomfortably close to the wires. That got the heart pounding even faster.

The second approach was lined up well but, being way too hot when I throttled back to flare she rolled quickly to the right towards the spectators (remember the right trim!). My reaction was to immediately throw in full left aileron and rudder to get her away from the people. There is a link below to a video of the sequence going from bad to worse. In the video it all happens very quickly. I remember a torturously slower series of events - left wing stalled 6ft off the ground and in a knife edge...manged to roll her level and desperately trying to build airspeed... got her flying but now 3ft off terra firma and heading stright for the tall trees... no choice but to turn towards the smaller trees which set up a repeat of the left wing stall .... pulled her through that again but now barely flying and have to climb over the trees ... somehow I cleared them and levelled to build more speed before trying to turn back towards the field ... Oh yes, time to start breathing again!

With a couple of bounces (still way too hot) I managed to get her down. The only damage was a bent nosegear steering axle pin and a clipped starboard prop. I felt VERY lucky!!!

To anyone who thinks that 2 OS FS-72's with 12x8 3-blade MAS props can't pull a 25lb plane out of serious trouble I have the evidence to the contrary - they performed well beyond my expectations.

The entire maiden from take off to finally stopping was 14 mins and 15 seconds - not much fuel left. One of the guys captured the exciting part on his iPhone. A link to that video on Youtube is below, along with a condensed version of the entire flight (Youtube would allow it all - didn't know there is a 10min limit). There are also several stills.

I flew her again this weekend and this time I concentrated totally on learning to slow her down. I now know that she flies happily at 1/2 throttle, even a little less, and about 1/4 on the approach is about right, coming down to idle gradually as she crosses the threshold and enter the flare. That results in her settling gently onto the mains. A condensed video of my second flight is also shown below. The early rotate and 'pitchy' take off were another operator error -during the engine run up I had accidentally pulled back on the elevator trim while adjusting the engine idle speeds - won't do that again!

Anyway, all is well that ends well. I hope the weather holds as I really want to fly her more.

Ron.

http://www.youtube.com/watch?v=VZgz8...layer_embedded

http://www.youtube.com/watch?v=S9P8v...layer_embedded

http://www.youtube.com/watch?v=w88Z5...layer_embedded

djstar39

My Feedback: (4)

Ron, first of all, congratulations on securing the job situation. Now that part is stressful!!

Yeah, the breathing thing... hard to imagine how worked up we can get over these 'toys'. Actually, I think that's why I like this hobby so much. There's not too much that gets your heart racing as you get older but this certainly does for me.

You are absolutely right about the perspective of NOT wanting to get a 25 pound airplane too slow on final. I'll take a hot landing over the 6 foot tip stall and pancake or cartwheel. Your second landing looked much better and I agree that you should stand where you always do from the perspective part.

The turn towards the pits. Yeah, nothing is worse that that feeling! I'll auger it in before I let it come near anyone. You did some awesome saves!!! Knife edge a couple feet off the ground on a heavy bomber is not something you ever want to experience again!!! I think you did an awesome job on your maiden! A little heart stopping but a bent nose gear pin and clipped prop are not bad considering how much worse that could have been. Order several of those pins as they do break from time to time (and take out the nose gear door in the process).

Again, congrats on the job and congrats on becoming a heavy bomber pilot! There's nothing like the sound of a good twin in sync is there?!

Dave

Mustang Fever

My Feedback: (2)

Ron:

Mine exhibited the same "left roll" characteristic due to engine torque. (I'm running a pair of OS 55 2s) It was so bad that the airplane almost wouldn't turn right at all, and, like yours, whenever I slowed down it wanted to roll right and was very touchy on final due to all the aileron trim I had to carry.

Counter torque weighting cured it completely. This came from that article in Model Aviation a couple years ago. Twice the engine displacement (2x 0.55= 1.1) in oz in the right wing tip. Two engines, so I put 2.2 oz of lead in the right wingtip. Completely different airplane. Neutral aileron trim. I can come in slow on final, nose high, and if I don't like what I see I can nail the throttles and all it does it pull straight out.

I've done this on a number of planes besides my B-25 that had problems with torque: 1/7 TF P-51; Outlaw; Bullet; Pulse 61; Pulse 25; and BUSA 1/4 DR-1. All now fly really well with no bad habits. The Mustang in particular was a marvel, before and after: before, it wanted to roll over on it's back every time I took off. Now, it just flies straight out.

A lot of people voice concerns about the airplane dropping a wing in loops, or on final. All I can say is try it. It doesn't happen. The improvement in handling will astound you.

For the twin 72 4S, I'd recommend 2x0.72+ 1.44x2= 2.88 oz. I bored 3/8 holes in the bottom of my wing tip, and used 130 grain 9mm FMJ bullets. They fit into the tip nicely and it's easy to cover over the holes.

Oh, yeah, one last tip: get all the flap travel you can. TF is very conservative on that, and the airplane needs all it can get to slow down for landing.

djstar39

My Feedback: (4)

Agree with Bob on the flap travel... as much as you can without the servos binding. I also use 10% on takeoff on our short paved runway. Makes a world of difference!

Dave

ronbell

Dave and Bob,

Thanks for the kind words and good advice. I did wonder about the flap setting but figured I'd better start with the values from the manual. Like you said Dave, using 1/2" flap on take off makes a world of difference. I'll start edging up the full flap setting until I find the value that I like.

As for the tip weighting, I remember that article but was unsure if the formula would be valid for a twin. Thinking more about it, it makes perfect sense as the engines are equally spaced either side of the fuselage so, from a torque standpoint they should behave just like a double-size engine on the center line. I'll definitely try that.

Thanks again. Happy Thanksgiving!!

Ron.

Jyjkoz

My Feedback: (1)

ok I have to order my motors tonight before my coupon expires....  These are my choices os 72 fs for $349 , OS  81 fs for $369 or OS fs95v for $299....Price isnt the issue its the size im am concerned about.. The reason I put the prices is the 95 is cheaper ? Any Input would help!!

acerc

Show871, here's a look at an a RCGF 15cc. The 20cc is the same size. About the size of a nitro engine.