hanna

My Feedback: (3)

Does anyone know where I can get a reverse rotation crank for a Moki 2.10. I am building a Yellow P-38. Any opinions? Thanks, Mike Krizan

fgpierce

My Feedback: (2)

Hey Hanna

Have you tried to contact Moki to see if they can provide you with one? I know Hobby People is coming out with a 210 and 180 2 stroke and they are dead ringers for the Mokis. But of course they aren't Moki (wink wink)
What prop are you going to use on the revese engine? A pusher?
I know I've heard of a gasser engine that can be revesed but can remember who. Try an internet search.
A p-38 with counter rotating props is well worth the effort.
Good luck!

Eric.Henderson

I can't remember if I did this on a MOKI or an ST, but if the front of the crankcase, the bit with the carb on it, is bolt-on, then you can rotate it 90 degrees and run the engine backwards???

Even if I am wrong it is an easy/harmless-to-the-engine test to try!!!

Which direction of rotation do you plan to run the left and right engines? I ran mine with the top of the prop going towards the fuselage, looking from the front. This worked best in case and when one engine flamed-out.

Regards,

Eric.

Newc

My curiosity has me on this one, so I'll risk embarassment by asking a question and/or making a comment...

It wouldn't seem to me that a different crank is the needed change here, but the at the change mentioned by Eric is what is needed - a reversal of the cylinder so that the correct intake and exhaust porting and timing is maintained with the reverse rotation. Is this correct or am I having a senior moment?

rrudytoo

My Feedback: (27)

Uh, no. While reversing the crankcase is doable, all it does is change the side that the exhaust port is on. This may come in handy if one needs clearance or a muffler within an airframe or the like.

Hobby People is offering Mark engines now but no parts. One of their cusotmer service technicians told me that they would, eventually, be offering parts, etc. in the near future. Stay tuned. Moki and Mark engines are one and the same so parts for one will work with the other.

Al

JeffH

My Feedback: (43)

The suggestion is to rotate the front bearing housing 90 degrees, not the cylinder. By rotating, the engine will indeed run backwards just find. I don't remember which way you are supposed to rotate the housing left or right. The exhaust will stay on the same side it is currently on.

rcmiket

http://www.justengines.unseen.org/ Not sure if they can help but as far as I know they seem to have the inside track on Moki parts ect, or at least point you in the right direction.

hanna

My Feedback: (3)

The way I understand it is the front housing can be rotated 90 CCW, but this puts the carb on the same side as exh port. Moki used to have a reverse rotation crank available for the 2.10. I have contacted Just Engines in England, they have one for a 1.80 and said they will check with "factory" to see if a 2.10 is available now. Mike K.

Multimaniac

Just my question - do you really need counter-rotating props????

Neither do I know the plane you are going to build nor the engines, but my experience from building many twins and multis is that I never needed counter rotating props. Sure, it looks great and may have some aerodynamic benefits, but for my purposes (e.g. on planes like the A.W. Whitley or the Turbo Panda, not fast planes but model twins that can be flown quite aggressively), I wasn't able to feel (in flight) a difference between counter-rotating and not-counter-rotating props....
I think the greatest "benefit" of using normal engines is, besides the lower price of the whole thing, the one that there is a vast variety of different propellers to fit your needs best. There is only a small sortiment of left-running props!

best regards

Chris

Eric.Henderson

Sorry if I confused the crankshaft question, The front housing on the MOKI can be rotated so that the carb points in the same directiuon as the exhaust port. If your engine installation can accomodate that layout then you can save yourself some big $'s.

I first ran into opposite prop rotation on twins when I was scratch-building an F7F Tigercat. I took two Enya 53 4-c's and moved the cams on one of them to get reverse running. You need two cams with their own gears driven by a central gear to do this. It was a blast breaking-in the motors on my son's trainer.

The regular motor was no problem but when I fitted the clockwise rotation motor to the same model things got a little funky. You needed a lot of left rudder on take-off which caused a left roll as soon as the airplane left the ground. Quite a high pucker factor was recorded several times.... The problem was that the engine needed left-thrust instead of right-thrust. To cut a long story we survided, even though we did amuse the peanut-gallery more than once.

The story on the F7F get even funnier. The opposite rotation on a twin really helps if you lose the port (left) engine. The reaction to the rotation of the prop on an anti-clockwise engine (normal rotation) does not help you keep the port wing up and level. A clockwise rotation on the remaining starboard engine helps keep the port wing up because the plane will naturally try and rotate in the opposite direction to the prop.

You can also set the side-thrust of the angle the engine to counter the turning of the plane towards the dead engine and thus reduce the tendancy to spin out. Opposite rotation engines can be set "opposite" on their wing panels. This makes the planes easier to fly and you lose less energy to the side thrusts employed on two engines rotating in the same direction. Next time you see a Twinstar just check out the angles of the engines that they have used to give good flying with one engine out! You will see what I mean.

Here's the funny bit; After messing with the Enya's and engine layouts etc for almost a year, I finally read beyond the F7F development book that I had been reading and using. Guess what? The prototype had opposite rotating prop's but the production version was modified to accept same direction props because it would require too many spares to be carried to support the fighter in field/combat operations!

Back to the drawing board [This was in 1987 BTW)

Regards,

Eric.

Sorry about the ramble but it is snowing and blowing a bit in NJ today....

hanna

My Feedback: (3)

Thanks for the input. I am seeking opinions on weather or not reverse rotation is beneficial. Rotating the housing is not an option now due to the way I have set up firewall. It can be re-done if I had to. Has anyone out there run the 1.8 or 2.1 with reverse crank or rotated housing? As for props I saw listings in the past stating they are available. Can anyone point me to a source? Thanks again for any and all info. Mike K.

fgpierce

My Feedback: (2)

HANNA

Here are some sites that may be of use:

http://www.masterairscrew.com/

http://www.zingerpropeller.com/Products.htm

http://www.airwildpilotshop.com/more...e=product&sku=

These are a few of the many companies that supply props of all kinds for the RC community.

Have FUN

You will find that out models will have behave much like their full scale brothers. Like in the case of the F7F full scale useing ssame rotation engines and the P-38 used counter rotation so you be the judge. For my money I'd go counter rotating. A Dead engine just may be the largest cause of demise among the twin engine population
OO
^
~

fgpierce

My Feedback: (2)

Right now I'm building 98" Dornier 335 arrow Fred Don Smith plans. It's a tractor/pusher. The aft engine is mounted in the middle of the fuse with a42" propshaft. The shaft has a coupling the attaches to the rear crankshaft of the G-45. Besides moving the engine weight forward it also has the great bonus of being able to use a tractor prop on the rear!

Getting too tired to type , time to close the eyes

hanna

My Feedback: (3)

I have enlarged drawings to do @110" 335. What keeps me from doing it is the rear engine location. I would like to see how the plans you have do the shaft ext. Does it use c/v joints and carrier bearings of some type? Mike K.

fgpierce

My Feedback: (2)

we are building a Do335 from Don Smith plans. We're using the prop shaft from Engel modelbleau & technik with a G-45 and Fema onboard starter . works great. The front power will be a brisson R50.both engines will have scale exhaust by J-tech .
Good luck