pieces

I am thinking of building a 4 engine plane. I don't want to get involved with a huge scale project. I would rather put my efforts into a reasonably simple build so I can concentrate on installing and running my 4 OS 25 FX engines. I am thinking of the Sig Four Star 120. Any suggestions ?
Chuck

Wayne22

My Feedback: (2)

I think the 120 might be too big..I have seen a smaller aircraft with 4 -46's and it seemed well matched. There are efficiencies by the additional propellor disc area, but there is only a total of 1 cubic inch of engines to drive them...with the engines, nacelles, extra servos, fuel tanks, and probably some nose weight, you might be looking at 12 to 14 pounds there. I've flown a 120 and it has a generous wing, so it would probably fly....it just would not be very exciting (unless you lost an engine ) Have you considered a 4*60 or an LT-40 ??? now that would be fun !!!

pieces

Thanks for the response. I have decided to build the Sig Four Star 60 instead of the 120. I am using a Futaba 6 EX radio. I need to find the right servos for the throttles to plug into a R127DF receiver. The throttle servos will be mounted in the wing. I want a smaller, lighter, dependable, and not to expensive servo to keep the 4 OS 25s happy. Any suggestions?
Chuck.

fliir

The Hitec HS-56HB is a sturdy, indirect drive servo. It is compact and only weighs 10.7 grams (less than 0.4oz)

evan-RCU

I used 4 HS-81s, on my OS .25's...

jaka

Hi!
If you intend to use 4 OS FX .25 engines in a plane you want a plane with a span of 220-250cm and a weight of 4-6kg

Wayne22

My Feedback: (2)

The Hitec 55,56, and 65 are designed for electrics- presumeably a vibrationless environment...even the HS81, I'd be hesitant to use....the gear teeth are incredibly tiny and they strip easily

pieces

Sig Four Star 60 with 4 OS 25 engines.

Hey Wayne 22, what servos would you run in the wing of the four star 60 for throttles? After reading up on some of these so called mini servos I agree that this type of servo is not what what I am looking for. I have no intention of putting this aircraft in the ground just to save a few bucks or a few grams of weight.
I am sure the servos will not be the only obstacle that I run into. I am also sure that out of all the rc people who are now reading this could have an enormous amount of ideas to share with me. I have a basic idea of what I am going to do right down to the nacelle design. But nothing is written in stone. How about some of you super smart rc people jumping in to share some of your ideas so we end up with a successful build.
Chuck

Wayne22

My Feedback: (2)

If it were mine......

Not a lot of torque is requried to move a throttle (provided there is no binding in the linkage), however, being mounted so close to a vibrating 2 stroke, there will be a lot of shaking transferred both through the linkage, as well as through the structure that the servo is mounted on....so you need something that will provide some endurance. I'd probably go for a 81 or 85 metal geared servo, or maybe the 225. depending on space and weight restrictions. I need to point out that I haven't used any of these servos in this application, but would be willing to give it a try, and would not hesitate to to swap them out if they were not up to the task. Plan B would be standard servos as they have proven they can handle the job in thousands of trainers over many years of service.....

Beauty of this hobby is that everyone does things a little bit differently, and you can learn from everyone.....

Wayne22

My Feedback: (2)

A couple more thoughts just occured to me........
The 4* series has open bay wing constrution right up to the leading edge. You would probably want to sheet the leading edge of the wing at least as far back as the main spar to take the loads from the nacelles....

Also, the Hobbico Twinstar has a neat compact arrangement for the nacelle which houses the tank, and servo, If you do a search, you should be able to find some pictures of the nacelle with the rear cover removed....there are plenty of twinstar threads in this forum, so I pretty sure you could find something.....In fact, you could probably buy parts from Hobbico to see how they tackled the situation and modify or copy to suit your needs.........

simhatus

Hi

My twin engine plane for 2 os 25 fp's i used 2 standard futaba 148's mounted in the wings behind the fuel tanks, had many hours of flying although it is in bits at the moment.

I have used the same for my 4 engine flying boat that isn't finished yet.

Simon

pieces

Sig Four Star 60 with 4 Os 25 engines.

Hello Wayne, I ordered the Four Star 60 today. I decided to use the S3151 servos for all functions.
So once I get over the fun of diving into a new kit I will go to work.
The first thing I’m going to do is build a prototype of the nacelle.
I need to fit a Du Bro 6 OZ fuel tank and a Hayes AL25 engine mount into it.

I plan on duplicating enough parts to construct a short mock up of the wing.
Where the nacelle slides into the leading edge I plan on doubling up at least 2 ribs with 1/16 plywood. I figure that will also provide a strong base to install the servo mounts. I am going to sheet the wing with 3/32 medium balsa from the leading edge back to the main spar both top and bottom.
I may have to add a couple of ribs to the wing so I can position the nacelles as close to the fuselage as possible.
I hope this thing gets off the ground.
Chuck

Scote

I have had great success with this setup.......Ultra Stick 60 platform-
-Twin OS 46Ax's
-8 oz. slimline fuel tanks
-3004 futaba...ailerons & elevater
-s9203 futaba or better rudder
-(2) HS 81 for the throttles

This was a great kit to modify...the wing has lots of room to conceal the tanks & add the throttle servos.
It flew great for over 2 years until last weekend... I was doing full throttle low level loops & could not pull out in time....It would hover rock solid(unable to torque roll it), unlimited vertical & a blender that would go into a blurr.
I will probaly buy another one to modify...maybe this time I will make it a triple just to change it up alittle.....0 thrust angles, if I flamed out I would kill the other engine & float in from almost anywhere...It flew on one engine but was a hand full to get turned around...it was easier to just dead stick it in....I'm going to miss "Ultra Sticky"

Edwin

My Feedback: (2)

I would do a stick type plane. In fact, I will be doing a stick type 4 engined plane. I'll be calling it the Herky-Stick. Since there are 4 .40's sitting on my bench with nothing to do I figure it would be fun to do a proof of concept type plane that would be quick and easy to maintain. rear cargo doors, Herk style landing gear and so on. Probably around 96" ws or so.
Edwin

heli_Rod

Sorry for the loss of a cool plane. You would think with that pointy nose it would have made a better "Yard Dart"!

A triple would have to have awesome power.....go for it!

Rod

pieces

Four Star 60 w/ 4 OS 25s
In the nose of the plane where the original engine was supposed to go I plan on mounting a camera. I want to capture the horrified looks of my fellow fliers when I get this monstrosity off the ground.
Hey Scote, Why don't you build a plane with 4 engines then you can keep the pointed nose. Actually it is easier to run 4 then 3 and If one goes out it's a whole lot easier to land.
I hate those unscheduled landings. By the way that was a nice looking twin before it’s untimely demise.
When I used to make those vertical landings I would pack the remains, put them in a cardboard box, and hide it in the garage so when my wife asked me how it went I would say ,� Great day honey “.
Good luck with your next project weather it be 3 or 4.
MULTIPLE ENGINES RULE.
Chuck

Wayne22

My Feedback: (2)

Chuck, it sounds like you are on the right track!!!

Scott, you should do a 5 engine Utlra Sticky! then you could could really impress the guys at Lando !!!!

rryman

My Feedback: (2)

I have the quality Fiberglass C-130, four O.S. .25's 17lb. dry weight, and it takes off easily at 3/4 throttle. I am using the HS-81 servos for throttle and have had no problems in 3 years or so. You will be surprised what those four .25's will drag around.

pieces

Sig 4 star 60 w/ 4 OS25s

Hey Wayne, I heard so many good things about the HS 81 servos that I went ahead and ordered them for the throttles. Next problem has to do with running 9 servos with a standard in flight power pack . That seems like a lot of drain on that battery pack. Would you recommend a larger capacity power pack.

I plan on using tri props on the 25s . I just haven’t decided what size and pitch to use.
How about some feedback on prop sizes.
MR. RRYMAN,Please send a photo of your 130.

Chuck

Wayne22

My Feedback: (2)

A larger battery pack wouldn't hurt...it also makes good moveable ballast for final balancing.

I am a big fan of three and 4 bladed props, but unfortunately, there just aren't any good ones on the market right now..The smaller Zingali and Master airscrew props are extremely inefficient. You might still find some APC 3 blade props in your hobby shop, but chances of finding 4 the same size might be slim... The best ones were the old Tornado props. Big fat blades and you could really wind them up and get some decent thrust out of them... When ever I see any in a swap shop, I pick them up....

You would probably be better of with 2 bladed props.... (I can't believe I said that!![sm=eek.gif] )

rryman

My Feedback: (2)

Pieces,
For some reason, I can no longer upload pics to RCU. But, if you go to page 2 of this forum, and check the "C-130" updates" thread, you can see pics of several Herks previously posted, including mine. I started that thread in Nov. 03.
Randy

fliir

Graupner has a fair selection of 3-blade props.

And don't forget the VarioProp - hubs for 3, 4 and 5 blades.

pieces

Hay Wayne 22,
I swapped the Four Star 60 for the Four Star 120. I think the OS 25s will do the job. The throttles will be opened by 81 servos.
Lets talk about three Blade props.
Question,
What happens to low quality 3 blades at the high rpm levels? It seems to me that the 3 blade changes its shape when subjected to high rpms. And in so doing changes the performance of your aircraft.
Bear with me.
A 17 pound C130 running 3 blade props may have a better chance of rotating on ¾ throttle. The props just might sustain there integrity up to that rpm setting. But a higher rpm setting could prove to be less productive. As you say , It flattens out. I have designed a test device that will measure the pull of a 3 bladed prop at controlled rpm settings. I think I can reach a happy medium by testing and comparing the results between 2 and 3 blade props. It’s possible that even a lesser quality 3 blade prop could still out perform a 2.
I also think I have to much time on my hands. I was forcibly retired from my job for an injury in 2004. I am gonna be 62 so I need to get going on this build.
Chuck

Wayne22

My Feedback: (2)

Okay, if you need to satisfy your curiosity....in the end you'll come to the same conclusion.

The purpose of a propellor is to turn rotational energy into thrust.... The two I previously mentioned are very poor performers in this regard. Regarless of the RPM, they just don't produce a satisfactory level of thrust. I know, cuz I've used them....
Graupner does make an 8-6 and a 9-7 3 bladed prop...I didn't know that til I checked...They would be worth checking out...

pieces

Hi Wayne,
You are right.
I guess my time would be better spent working on the plane.
I am trying to increases my chance of a successful build by doing some homework ahead of time.
I appreciate those of you who are writing in with your ideas.
I will try the Graupner 3 blade. And as much as I hate to say it as a last resort I can always fall back to the 2 blade. ( how humiliating )

Keep em flying.
Chuck