MormonMike

My Feedback: (2)

Guys, its great to see you "Duelers" push forward on a great kit but, let me have my two cents worth , 300 hours into mine and only four flights before one of the engines quit at the worst possible moments will sure take the wind out of your sails. The best and most meteculus pre-flight, nothing over-looked, wont do you a bit of good if one of the engines quit for absolutely no logical reason. so , take this bit of advice, dont use two-strokes, use the more reliable four-strokes, a scoche rich and hopefully your plane will be around for a while. i will probably build another, but for now, twin electrics are the only ones i will fly. Sorry im gripeing or complaining but dang it!-------loseing that one hurt!................. A tail dragger version.....Hmmm, I ll keep that in mind

JL1

My Feedback: (93)

I am not trying to be antagonistic, but I do not understand the idea that four strokes are more reliable than two strokes. I see just as many flame outs and problems, if not more, with four strokes. I would be interested in your views on this and why you feel that the 4's are more reliable.

MormonMike

My Feedback: (2)

Greetings, i knew i was going to kick a hornets nest. Answer, my 10 four-srokes that i own simply never give me the problems my 5 two strokes give me, matter of fact i cant remember the last time i had one of my 4 strokers quit on me, its been that long ago. its all a matter of personal opinion.

JohnBuckner

My Feedback: (1)

I kinda of agree Layton I see just as many flameouts at many fields with 4's as with 2's and think its really more a matter of how you educate yourself. Have built and flown six twins all with two strokes of various types and never lost one to a flame out, but have lost some to other causes. This is why my current four engine project has 2's on it and you know the sound with all four in sync is even sweeter than 4's, how's that for a twist?

mjs this is not intended as a flame just a bit of good natured rebuttal


John

Oh yea my Mama once told me that electric multi's is cheatin!

FLYBOY

My Feedback: (11)

I have 35 two strokes and have given every four stroke I owned away but two that I haven't run. Don't like the four strokes that much. I have absolutly no problem with twos, but the fours have no power and quit frequently. Nothing against them, just like the twos a lot better.

Consequently, when your engine quit, did you leave the power on the other or shut it down? Just curious.

mucksmear

From what I've seen at the local field, most (but not all) engine reliability problems stem from improper adjustment of the needle valves, etc, and from problems with the fuel storage/delivery system rather than something specific to whether or not the engine is a 2 or a 4 stroker.

I've had about 5 flameouts on my duellist. One of them ocurred when the model was at relatively high angle of attack, very low airspeed and at full throttle. That's about as bad as it gets. The only thing that saved me was my altitude and proper spin recovery.

Another flameout ocurred at equally low speed, with the model in landing configuration, essentially level, shallow descent, low power setting, gear down. There was not even a hint of asymetric thrust induced yaw to be seen.

Keeping it light as in close to the "advertised" weight will go along way in reducing the amount of power required to keep it flying. A reduced stall speed will also help reduce the minimum single engine out control speed.

Agreed, the Duellist is not a beginners plane. It is after all a twin. You should be proficient/comfortable with flying fast low wing aerobatic models WITH rudder control. You should also be comfortable with spin recovery.

Btw, the 2 strokes in my Duellist are also inverted.
Begging for trouble? not really. The engine setup is nearly identical to the engine set up in one of my reliable single engine models.

-Elliot

MormonMike

My Feedback: (2)

To John B. and Flyboy, These were well broken-in STs. The port engine quit on climb-out about 25-30 feet into a left-hand bank away from the run way. i do a perfect by-the-book preflight,with a spotter/co-pilot to help me. there simply was not enough time , speed, altitude for emergency procedures. Also , I do not "sync" the engines, rarely do 2s run perfectlywhen your tuning them by sound. I start one up, run it up till its just a click or two on the rich side, shut it down and then do the other. If they sound the same its impressive, but my expirence shows me that one may be running too rich or lean to get that sync-sound. I still cant figure out what caused my duelist to lose an engine. However! Im undaunted! im talking my freind out of his kit and yes , itll be a taildragger, shorter nacelles, one big fuel tank in fuselage, servos in tail area and ultracoted wings with a long nose. MJS {michael} P.S. Electrics are not for "woouses" or "panzies" They make em just as big and expensive as a duelist [L-200, Kavan Partenavia, etc] Seeya guys

ChuckAuger

My Feedback: (12)

Yeah, it's rough when you crash something you put so much time into, twin or otherwise. Doubly troublesome when the cause of the flame out is unknown.

When I built my Duellist, I was convinced it wouldn't last long, but I wanted one, so what the heck. My goal was to get 25 flights..I was blessed to pass that mark several times over. I've had 2 engine out situations, and they were both from running out of fuel.

Glad to hear you're getting back on the proverbial horse.

FLYBOY

My Feedback: (11)

I am guessing it isn't something you did, engines flame out at times. Might have fouled a plug. The reason I asked about the power setting on the engine that kept running is a lot of guys don't know about Vmc, which is the speed at which you loose rudder authority. If you have full power on the good engine and you are taking off, the number is higher than if you pull the power. P factor and torque have some to do with it too. If you get some or all power out of the running engine, it won't flip over. If you are low, it is tougher. Gotta kind of commit to just landing straight ahead no matter what is there, kind of like a real plane. Light twins usually don't have the power to climb on one engine.

OldRookie

My Feedback: (13)

MJS
I was reading your modifications to the Duellist kit with quite a bit of interest, as I am also about ready to start mine.
Will you be using some sort of pump on each engine to get fuel to the engines, seeing as you will only have one central tank?
I take it that the Duellist comes out nose heavy. Is this the reason to shorten the nacelles, and move the servos to the tail?
Why lengthen the nose? Just for looks?
I also plan on making mine a tail dragger. How far ahead of the center of gravity should the wheels be placed?

Greg

MormonMike

My Feedback: (2)

Oldrookie, Yes , the duelist comes out very nose heavy,shortning the nacelles and a large common fuel tank might be better. also a taildragger configuration would take the nose gear weight out up front and servos to the tail would help quite a bit. Maybe a fuel pump will be needed. With that type of fuel tank setup it will probably need mechanical retracts. Im also considering flaps for obvious reasons. It would be a massive winter project but what the heck.......DO IT! Ultricoteing the outer wing will help onthe weight problem to. Stay in touch. anybody else have some better ideas lets here them, seeya MJS

MinnFlyer

My Feedback: (4)

FLYBOY, When you give away those other two 4-strokes... GIVE THEM TO ME!!!!

ChuckAuger

My Feedback: (12)

I can't figure out why a Duellist would be nose heavy. Mine was built per plans with .46 sized engines, I even have aluminum spinners and it balanced beautifully. I run a throttle servo for each engine, an 8oz tank in each nacelle, a servo for each aileron...AUW is 9lbs even. I have a 1500Mah battery right at the rear of the wing saddle. Tricycle configuration, Rom Air gear, Monokote covered..that's about all I can think of.

Kit bashing is part of the game, I hardly ever build a kit spot on the plans, but I've seen 6 Duellists from local modelers, and none of them had to resort to shortening the nacelles. If you plane is coming out nose heavy, you might look at some other issues, there have been lots and lots of Duellists built with the stock nacelles. Just my observations.

FLYBOY

My Feedback: (11)

Minnflyer, they are actually in a glass display case along with a bunch of other engines. The Saito 180 will fly in my G-202 once in a while, but as of yet, I am not happy with the way it runs. Might just need more breakin. Only flown it 4 times. I think I landed deadstick 3 of them. Least the last time it stayed running. I haven't tweaked it yet either. Probably most of the problem. Gotta set it right to make it run right.

mucksmear

OldRookie,

Mine also balanced close, but slightly on the nose heavy side (with the gear down).

Rather than shortening the nacelles, you'll probably be fine just moving your rudder/elevator servos aft a bit and probably even your Rx battery. Use a large capacity Batt to assist with all the servos (especially if you go with mechanicals, 2 ailerons servos and 1 or 2 flap servos. A large batt in the right place may even be all you need to achieve proper balance (mine sits right behind the canopy).

Doubt you'll have to move the servos all the way to the tail though.

There's some info on how I set up my fuel system, and mechanical retracts (taildragger) at

http://www.elliotfan.com/temp/duelist.html

If you'd like, I could take some photos of the various insides of the nacelle/gear bays, and fuselage and post them.

Regards,
-Elliot

JohnBuckner

My Feedback: (1)

Mucksmear neat project a Me 246 ?? He he. Enjoyed that imaginative write up at your site. My Duelist was a minor bash as a wanna be Focke-Wulf Ta-154 with a triple tail, yes I know the 154 didn,t have a triple tail but what the hey it looked cool. Early on this ship was my pylon callers airplane and we used it as a practice airplane for SWRA races and our scale racers a Royal P-38 and a F-82. It was equipped with Rossi .45's and was a deligthtful flyer but eventually met its end in a midair during practice. I ended up with the wreakage and did rebuild it up to its current stage near ready for cover and am planning TT .46's. The one important mod I did do was building in four degrees out thrust on both sides and on this ship I feel that will be a huge asset at flameout time with those engines so far out on the wing. Out thrust on both sides on some of my other multi's has proven to make all the differance in the world come surprise time.

Anyway great write up on your site. 'Keep um Singin'

John

mucksmear

Hi John,

Please post some pics if you have some, of your "154". Did you make any other mods, structural, rigging or otherwise beyond the "154" aesthetics and the out thrust?

Cheers,
-E

JGrc

My Feedback: (29)

MJS, be aware that shortening the nacelles may increase Vmc. What would be the advantage of only one fuel tank?
JGrc

JohnBuckner

My Feedback: (1)

-E, actually it was a totally bogas all black film with iron cross' just for fun Neither my caller or I had built the airplane so I have no idea what is original or not. It has fixed tri gear in wing blocks with the mains angled over to the center of the nacelles.

Another mod the original builder had done was the tip fins of about fifteen percent area of the main fin/rudder. They are mounted at the ends of the stab with about three to four degrees of outward deflection. In other words the right tip plate which is directly behind the respective engine deflected flow to the right and the left tip plate did so to the left. Now I believe what the original builders intent here was; with both sides running and both tip plates direcly behind its respective engine both plates would see higher energy airflow than freestream flow over other portions of the aircraft. With both deflecting air outward there would be no yaw from this and true there is obviously somewhat of a drag penalty. Now when an engine fails there is no longer high energy flow over the tip plate on that side but there still is over the plate on the side with the running engine which would result in a net yaw automatically into the good engine side which is exactly what you want in a flameout. In my 10 or 12 flights with it I did not experiance any stoppage so could not say how effective this is but did wittness two flameouts with my partner flying and in no case did the resulting yaw roll become uncontrolable to the point all remaining power had to be pulled off. Perhaps this simple idea is a benefactor to the ships survival? The only real change I made during the rebuild after the midair is the application of out thrust on both sides. This is one thing that really works. Most full scale light twins employ out thrust on both sides and it lowers the VMC considerably, I just don,t understand many model multi designers reluctance to use it. In the case of one of my bashed twins a forty size trainer of some sort with a pair of twentys the VMC was sufficiently low to allow on two occasions when I was feeling brave (dumb), to take off with the critical left engine shut down and just the prop removed.

I am sorry I am to dumb to be able to post pictures so I can,t show the Duelist But if this link works a friend posted some pic's at another site for me of a quad Kaydet thats nearing completion now with four Magnum .28's. On this one I have about three degrees out thrust on the inboards and near five on the outboards. John Try this

MormonMike

My Feedback: (2)

JGrc, no real advantage in shortning the nacelles, its just that with a single tank on top of the wing , you dont need all that nacelle sticking out in front. i was useing ST .51s and the mufflers on them are as heavy as the engine itself. I hate to say this but my duelist weighed in at a whopping 12 pounds but , i now know how to shave off 3 pounds on the next one. i wish i could figure out how to post some photos of it here but i cant figure out how to do it. it "WAS" beautifully done. if any one can tell me how , i will post em. MJS

FLYBOY

My Feedback: (11)

shortening the nacelles won't affect Vmc, but moving the engine in or outboard will. Remember also that the arm on the right engine is more critical than the one on the left engine, meaning if you loose the left engine, it will cause more problems than the right one will. The decending blade takes a bigger bite of air per say and is farther out on the right engine, so it has nmore of an arm to cause a spin.