I've finally finished my Widebody 60 and have just made a couple of flights. I installed an OS 90FX with an APC 13x8 and have noticed that in striaght climbs it isn't as powerful as I should have expcected. I thinking of several solutions, or combination of them.
- Change the propeller to a 13x7 or 14x7. Any recomdendation on the propeller size?
- Install a pump. I had thought of a perry oscilating pump. Which type would be the most apropriate?
- Change the carburetor. I had also thought of a perry carburetor. This change is due to the slow responde the motor has. It takes quite a while before it gets to its top rpm. Which carburetor is the best?
I hope someone has some experience with this changes and is capable of telling me which is the best. I haven't thought of changing the muffler, basicly becuase it would mean major changes in my airplane.

Hi!
i have one installed in a design off O.Fremming from Norway its light but have no problem with performance or the engine what so ever!
i use a apc 14 x 8 a pipe i don't know what type is and the plane weigh ca 3,4 kg u can launch the plane vertical!
the engine is straight out off the box ..no pump and original carburetor , i was thinking about to install a set from the Os 61 Hanno but haven't don that , after 100 flights ...not one stop in the air!
is it any other problem than the vertical performance?

A Perry Pump (VP30) solved my "problems" with the 91FX. Now I use an APC 14X10 on my Widebody.

Hoeknu, what type of problems did you have? How was your throttle response?

Hoeknu, what type of problems did you have? How was your throttle response?

I put a mousse can muffler on my o.s. .91 and gain more 1000 rpm's, plus it's a lot lighter.
Also, just taking the baffle out of the stock muffler made huge gains, and it wasn't that much noisier.

dave hauch

CEV, it leaned out in the long verticals. My throttle response was pretty good though, and with the pump the pressure remains constant through every maneuver.

dave


Do you have any pics of your mousse can muffler for te 91fx?

Sorry no pics, there was a guy that posted his at a thread I started on a mousse can for the .91
at the profile & funfly topics.

Search for ''my mousse can dimensions for o.s. .91 fx , I have mine all listed there.

If you can't find anything email me at djunruhQqtm.net and I'll help you out, real easy to make. plus I did alot of testing with different variations and found the perfect system.

dave hauch

CEV,
Before you go to a Perry pump I suggest you check a couple of things: use a good plug - OS A5, or a No.8; make sure the tank outlet is is positioned level with the carb spray bar. Also use 15% nitro if you can. A mouse can muffler is fine for a Funfly but for a Pattern Plane like a Wide Body 60 you might do better with a Macs Muffler (the OS 61FX fits the 91). Better still go with an "S" header (manifold) and a Hatori type pipe from Just Engines in the UK. But check the tank position first.
Saludos

Rodney,
I'm using an OS No.8 Plug and a 10% nitro. During the construction I really made an effort to try o have the tank's outlet leveled with the carb spray bar, and I finally did, but even though the engine seems to lose some rpm when it is in a vertical climb. I installed a glow charge valve and think it might have something to do.
I have also noticed that using a Master Airscrew or an APC makes a great difference.
Before trying to put a muffler with all the modifications involved in it I thought a perry pump would be a cheaper and easier solution.

CEV are you flying at altitude?
The reason I ask is that I am flying a CZ models rebelove 6lbs10oz on a 14/8 spinning at 9800rpm on a standerd exhaust and 10500 on a pipe with 10%nitro 18% oil and an enya 3...this combo is simply balistic as in vertical out of my hand

CEV,

How much your widebody weighs? I am using a 91 FX on my K-trick 90 which weighs about 3600 grams. With straight 80/20 non nitro fuel I hand launch it vertically 90 degrees and it goes vertically unlimited.I am using APC 14x6, coz I prefer low pitch for better vertical. no problem with the carb.

Are your fuel lines too long or there are multiple bends of fuel line which can cause head loss of pressure? check your fuel tank also.

IT IS THE PROPELLER!!!!!! Change the flat paddle to a real prop.....In my experience MA props bends and twist under load. They surely rev up, but the lack in the thrust department. I would only used it in a trainer.

Thank you for all the answers. Let me go by parts.
I actually fly on the top of a moutain 600 m abobe sea level. The final weight of the airplane is 3,5 kg. I'm now using a Master Airscrew because the landing strip is full o tiny stones that break off the tip. In my fisrt flights I used a APC prop and it went much better. I think that using an APC 14x6 or 14x7 will make a big difference, I'm sure of that. In my club the Master Airscrew are well know for their bending, but we normally use them becuase they usually get choped down.
Any way I'm still thinking the pump might be a good idea. I have revised the tank-carb alingement ant tried to reduce tha number of couplings, bends, and so on to the minimum. I think that is not the problem.
I still have the problem of the carburetor response. Any suggestions?

Just take out the baffle from the stock muffler n use an APC 14x6. See the difference. No need for any hopups....If with time u dont like the vertical, u might think of putting up a tuned pipe.

I am flying a WB with an OS 91FX with a Perry carb. It is swinging an APC 14x8. At 6 pounds 8 ounces the vertical is nonstop. I don't have any RPM numbers, but I really like the combo. I am using K&B 1L glow plugs and 10% Cool Power. I fly at 600 feet above sea level.

Bryan

What perry carburetor have you got? The "Perry Large Carburetor O.S. .60"?

Just flew my Widebody for the first time tonight- O.S. .91 FX with Std Muffler W/ Baffle, silicone exaust deflector, 2.25 Truturn and an APC 15x7. Seemed the perfect combo of thrust and speed, and didn't over rev. also the 16 oz. tank gave some long flights. I would stay with the 15x6 or 15x7 for the .91 Fx. My Dad runs a .91 Fx on his goldberg Extra with a bisson pitts muffler and an APC 15x6- little louder than mine, but pulls great all the same. We both have tanks right behind the firewall and are running stock carbs without pumps.

Brian, what are you getting for rpm's with the 15x6 ?

I'm getting around 11000 max rpm running a mousse can muffler, just curious what yours is with stock muffler.

dave hauch

CEV,

I am using Perry part number 4501 HI-Pro carb and a standard silencer with the baffle.

Bryan

I think Dad was getting 10,000-10,500 on the ground with the BCM Pitts and 15% nitro. I only have 3 tanks through mine with a 15x7 and 10% nitro, and I haven't tached it yet, but I am hoping for 9000-9500 with the stock muffler. The 15x7 unloads a bit in the air, but probably because its not yet broken in completley. we will see once I jump the nitro from 10 to 15% and go down to 16% oil from 18. Plan to fly it again tomorrow and will grab a new battery for the tach before I go. Stay posted!

I switched back to stock muffler with no baffle, with a 15x6 and lost 1000 rpm from my mousse can muffler, 15% fuel.

dave hauch

Dhauch,

I've tried to search the page you mentioned a couple of days ago about the mousee muffler but haven't found anything. I also tired to send you an e-mail but also had problems. Could you tell me the exact web page or any place where I could get information about the mousse can muffler.

Thanks,

Carlos

here is a site with how to build one; http://webpages.charter.net/rcfu/ConstGuide/MCM.html

I used a MAc header, which the overall length was 8'' of just header.
Can is 2 1/4'' in diameter, about 10'' long.
Stinger inside diameter was 1/4'' and about 3'' long.

Hope this works for you.

dave hauch