dleclaire

Ok,

so up for debate,

counter rotating dle20 or perharps rcg20

anybody done it?, anbody have any thoughts, Ihave done it on a G23 in a twin gas boat
with ignition coils, took a while to get the timing down but it worked out awesome

also looking for a good source for the CDIsynchornizer that I would like to add to balance the
engine RPM's

3136

I just looked into doing this myself for a twin.
First of all you can use a twin sync from wike electronics to sync two motors, if one cuts out it drops the other to idle.
http://www.troybuiltmodels.com/items/WRCTWINSYNC.html

As for running a rc engine in reverse, Jedijody ran a dle 30 in reverse but said it had to be set a lot ritcher.
The dle 20 has a timing bump which alters at a certain rev, they may be a bit of a problem to use in a twin but if they are syncronised it could be ok.
Everyone I spoke to said in model application you didn't need to worry about making them opposite rotating,
I emailed EME they said it's ok to change the reed switch/hall sensorlocation and run it backwards, not sure if I'll worry about it though.
I was going to use the EME35 in mine as they have an onboard electric start for their 55 and 60cc,(which also fits dle 55 and DA50)they will have it for the 35 in a few months I'm told.
http://www.sdshobby.net/special-elec...e-p-11462.html
That would be pretty cool, sitting at the flight line, start one engine up via the tx, then the next, taxi and take off, nice and scale</p>

All Day Dan

My Feedback: (5)

dleclaire, don’t overlook the fact that you will have to use a crankshaft with opposite threads to avoid having the prop coming loose. Dan.

earlwb

Well, it is certainly a doable option. Yes one can reverse the engine rotation by reversing the ignition timing. You need to move the sensor so that the static timing is reversed. The CDI unit doesn't care if the engine is running in either direction.  As to performance, you shouldn't see any difference worth noting with a reverse rotation versus a normal rotation engine.

But for twins, you do not need to reverse the rotation on one engine. The planes fly fine with both engines rotating in the same direction. All of my twin engine planes are using normal rotation engines on them. They fly fine like that.

Reverse rotation may be of more interest for guys flying a pusher plane with the engine in the back. The selection of pusher props is quite limited and using a reverse rotation engine lets you run normal props then.

CK1

My Feedback: (60)

Several years ago I spoke with a pilot who had reversed one of his engines , He wanted it "scale " . Come to find out he regreted having the reversed engine . He rarely flew it and sometimes couldnt figure out why one of the engines wouldn't start , he had been flipping it in the wrong direction. On top of that another pilot pointed out that he had flown the full scale plane and in fact the full scale engines rotated in the same direction on that plane . Bummer ......

The point is why make things more difficult for yourself .

Bill Wike makes a great engine synchronizer called a "Twin Synch" , I think Troy Built still sells them. There is a thread here on RCU
http://www.rcuniverse.com/forum/m_47..._1/key_/tm.htm

3136

Hey Dan, a lock nut should fix that.

dleclaire what aircraft do you want it for?

earlwb

I think if you are going for every scale point you are getting at a scale RC plane contest, then you would want conter rotating props. Otherwise there really isn't a reason for it.

The only plane I know of with "outwardly" rotating propellers was on the P-38 Lightning.  They did build the first prototype with inwardly rotating propellers, but it crashed and they changed it after that.

ref http://www.ww2aircraft.net/forum/tec...rds-10566.html

Now then it was stated in Wikipedia:
 http://en.wikipedia.org/wiki/Counter...ing_propellers


I didn't know it until now, but these other planes here have counter rotating propellers too:


The following aircraft have counter-rotating propellers:</p>

Single engine, chain driven propellers :</p><ul>[*]<font color="#0066cc">The Wright Flyer</font>[/list]
Twin-engine, one engine per wing :</p><ul>[*]<font color="#0066cc">de Havilland Hornet</font>[*]<font color="#0066cc">Lockheed P-38 Lightning</font>[*]<font color="#0066cc">Heinkel He 177</font> Greif (fourth prototype onwards)[*]<font color="#0066cc">Henschel Hs 129</font>[*]<font color="#0066cc">Piper PA-31 Navajo</font>[*]<font color="#0066cc">Piper PA-34 Seneca</font>[*]<font color="#0066cc">Piper PA-39 Twin Comanche C/R</font>[*]<font color="#0066cc">Piper PA-40 Arapaho</font>[*]<font color="#0066cc">Piper PA-44 Seminole</font>[*]<font color="#0066cc">Cessna T303 Crusader</font>[*]<font color="#0066cc">Beechcraft 76 Duchess</font>[*]<font color="#0066cc">Piaggio P.180 Avanti</font>[/list]
At least four engines, two or more on each wing :</p><ul>[*]<font color="#0066cc">Messerschmitt Me 323</font> Gigant transport[*]<font color="#0066cc">Airbus A400M Atlas</font> - first aircraft with propellers in counter-rotating pairs on each wing[*][/list]

dleclaire

Im building a G&amp;L hobbies p-38 lightning, and Yes I was definately looking for the scale look,

thanks everyone for the input, and especially the synchronizer information as reverse or not, Idefinately
will be adding that feature to the bird

apalsson

My Feedback: (1)

I have a project going with the Wendell Hostetler Cessna 421 where I will be using two Zenoah G62 and counter-rotating props.
My engines were converted by Ralph Cunningham but in brief, the only thing we had to do with the "backwards running" engine was to move the ignition pickup 28 degrees on the other side of TDC. We also added a pair of safety bolts into the hub of the backwards running engine to protect against the single bolt setup loosening up the nut because of the direction of rotation
I will be using a pair of 3-blade Menz props, one pusher and one puller

2 stroke, single cyl engines don't care which way they run, it's simply a matter of the timing

3136

Good stuff guys, I'm doing the Henschel 129, I probably wont bother counter rotating the engines, but nice to know its possible.
Not too sure how heavy it will be, 2.8m span, prob 14kg or so, I think 2 35cc will be fine. It will be built up balsa and glassed.

rich thomas

might i suggest one fueled motor and a spiffy gearbox, for one nacell. and one without? or one nacell with one fueled or electric motor, and a gearbox for both directions? maybe a counter rotating pair on each nacell? just sayin'. it's all fun. flight characteristic differences as per the plane size should be of minimal concern. deep pitch and power...