rwithey

My Feedback: (3)

I have a scratch built model of a Junkers JU-52 I purchased from a fellow club member. I have not weighed it. It has a 7 foot wingspan and is 54 inches long.

It flys well with an OS 25 in the nose and two VECO 19's in the wing.

But it sounds like a swarm of bees in the air.....

I am ready to replace these three two strokes with three four strokes. Any suggesgtions on motor choices? I am considering a few options......

I have an OS FS-26 I can use in the nose. I could buy two OS FS-30's or FS-40's for the wings, or two Magnum XL-30RFS or XL-52RFS to save cost.

Or purchase thee of the OS or Magnum's listed above and save my old FS-26 for another project.

Do you think the XL-52RFS motors would be overkill. I kinda like the idea of them since they are more easily matched to future airframe choices.

I can't find any power ratings to compare the Magnums to the OS's to the two strokes.

Any advise would be appreciated,

Rob

Flyboy Dave

My Feedback: (21)

....I'd go with three Magnum .52 FS engines....they are really sweet running.

FBD.

NikolayTT

Wait for a moment, 4S will have lot more vibrations, isn't it ?! I would stick to 2S unless reinforce the
frame properly.

Wayne22

My Feedback: (2)

7 ' span..... that's a pretty sizeable airplane. I have a 3 engine twinstar that is much smaller but has 2 26's and a 25...... almost adequately powered... I'd look at engines that are a bit bigger....

TLH101

My Feedback: (90)

Huh?

rwithey

My Feedback: (3)

The plane was very well built - I am not concerned about damage from more power or vibration - which is likely not an issue anyway.
I have an Ultimate Bipe I had a ST G90 on that made a terrible vibrating noise at full throttle - switched the G90 for a Saito 120 - noise gone.....

I am really leaning towards three Magnum 52's - maybe two with my OS FS26 in the nose.

Thanks for all the input so far....

Rob

JohnBuckner

My Feedback: (1)

The sound your are getting with the original engines is due to the deliberate mis match of engines. In my opinion that is a poor idea with any Triple.


I have used Magnum thirty FS's on a twin and found them to be somewhat disappointing in power and even worse sound like an old tennis shoe tumbling in a clothes dryer. That airplane a twin is a much better flyer now on OS 25FX I also convered over to the OS from magnums on my Quad.

rwithey

My Feedback: (3)

The sound was on a single engine Goldberg Ultimate Biplane, unless you are referring to the swarm of bees sound of the three two strokes on the tri-motor.
You are probably right about mismatching engines being a bad idea on the tri-motor, I likely will go with three identical engines.

Rob

Wayne22

My Feedback: (2)

or you can put a bigger engine in the nose, and two smaller ones on the wing....nothing wrong with that! As long as the engines get fuel and air, they will continue to run...nothing changes because it's neighbor is a different size.........

acobra

My Feedback: (40)

Hi:
Just found your post on the JU52, I'm the designer of this plane; it was featured in RCM more than 10 years ago. If it is built per plans it'll fly very well on 3-.30 four strokes, The original flew on 3-K&B .20 sportster bushing bearing engines and any engine out was not a problem, it just kept on flying. Don't use too much engine multi's are much more efficient that singles.
acobra

beenie

My Feedback: (9)

I had the Magnum .30 and ran the hell out of it. It may be my highest time engine. It still runs but has lost some power. It was purchased to fly a 5.5lb Sig 1/6 scale cub and had enough power. Not a lot of power, but enough to provide nice scale like flying. I put in my 3 lb lazy bee and then in a scratch built ag cat of similar weight. I didn't find the sound to be that unlike larger 4 strokes and the power was fine. Wouldn't hover the 3lb planes, but would hold them up for a moment. Really a nice little engine.
I have 2 of the Magnum 52fs on a top flight DC3. They sound great running together and run well. Havn't had any trouble with them yet. They are a good bit heavier than the 30 though.
Ben

rwithey

My Feedback: (3)

Thanks for the info acobra. I finally ordered two OS FS-30's last week and decided to use the OS FS-26 I already had from my cub in the nose. I flew it today for the first time with the three four strokes. Sounds much better than with the three two strokes. Power is also much better than with the two strokes. I am very pleased and definately think the 40 or 52 sized four strokes would have been WAY over powered. It barley rolled three or four plane lenghts before it lifted off.

Do you know if plans are still available for this plane? I would like to obtain a set for reference and in case of a future mishap. I really like the plane and would want to build another if this one was lost. You obviously did a great job designing it. Have you heard of anyone sucessfullt creating the corrugated look of the full scale?

Thanks,
Rob

acobra

My Feedback: (40)

Rob:
Glad to hear all is well with the 52, I bet the 3 4-strokes sound great. I think the plans are still available from RCM. They don’t have a magazine any more but I think they still sell plans. If you can't get it from them let me know in a PM and I'll see what I can do, I may have a set around here somewhere. How about sending me a picture of your JU-52? I herd of someone who used the corrugations from inside cardboard to simulate those on the 52 but that to me would be overkill for this plane. Perhaps just use a light grey sharpie and put on a bunch of lines. But if you get a chance pick up a November 1990 RCM with the construction article in it and read the explanation I gave for the lack of corrugations. (so much BS but, it sounds good)
Frank

Ed_Moorman

My Feedback: (1)

We have had our Magnum .52 4-strokes on 3 different twins and are getting ready to put them on a fourth. They have never quit in the air. Excellent engines. Based on my experience, I would recommend them.

rwithey

My Feedback: (3)

Thanks Frank,

I searched RCM web site and found a PDF file of the construction article!
http://www.rcmmagazine.com/issues/re...KjrijMLTY0J3v7

It looks like the plans can be ordered, I am a bit hesitant since I was one of the many who got ripped off when RCM suddenly closed.
I ordered a year subscription and never received a single issue.
I went round and round with them for months requesting a refund and they finally quit responding after multiple empty promises.
I later found out they accepted my money months after they printed their last issue!
I would really hate to give those theives another nickel of my money! I will have to give it some consideration but would want to speak with a live person - but they never answer the phone.
If you have a spare set of planes I would gladly pay you their asking price! $20.50 plus shipping.

I noticed my JU-52 was built with a few differences.
The wing is one solid unit, not 3 pieces - and no flaps.
Also all three engines are controlled by the throttle channel only.
When I installed the four strokes I separated the throttle servos into 3 channels using programable mixing on my Futaba 9CHP.
This allowed me to independantly set endpoints and idle positions.
The only photo I currently have is the one I started this thread with. It is a digital photograph of an actual photograph the builder gave me.
I have taken the old FS-26 out of the nose for a cleaning and when put back in I will take a digital photograph and post it.
The builder covered it as a Lufthansa airliner - I would like to eventully recover it in a military scheme, which is why I was inquiring about the corrugated panels.

Rob

jrf

My Feedback: (551)

RCM Plans Service is no longer run by the folks at RCM. They sold/leased/licensed (or something) to somebody else, so although the old owners of RCM might get a small royalty, most of the money goes to the person who actually makes and ships the plans.

Jim

rwithey

My Feedback: (3)

Hi Frank - I finally finished recovering the JU-52.
I attached a pic of the model and the full scale I copied.

Rob

acobra

My Feedback: (40)

Rob:
Looks great, I keep thinking I'll build another one but there just so many other planes I want to do I never get to it.
Frank

rwithey

My Feedback: (3)

Here is a new photo and a link to a You Tube flight video another club member shot.
I REALLY like the sound of the three four strokes!

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

Rob

acobra

My Feedback: (40)

Rob:
Looks and sounds GREAT in the air. Good memories. Special thanks for the video.

The Bluehead

Wow Rob, that is excellent. That is also the paint scheme I want to put on mine. Unfortunately, I hit financial problems, so it took a back seat this summer/ fall. Hopefully, I will finish it quickly when it gets warm enough to fiberglass and paint it. I can't wait.

Great job once again,

Will

rwithey

My Feedback: (3)

Thanks again for the compliments guys. I really enjoy the plane and it always grabs attention at the field.
I browsed online for full scale JU-52's and chose this scheme just cause I thought it looked good. The covering is all Monokote.
Funny thing, I didn't realize until after I recovererd it and was working on the club website, that the tail markings might have a hidden meaning.
I was cutting and cropping a picture and made a mirror image of it when I realized the "AZJU" markings in mirror image and after dropping the "J" spell "USA"

Rob
www.lcrcers.com