My 50 -cc gasser build thread

Harveer · October 24, 2010, 11:51:05 PM

Quote from: anwar on October 24, 2010, 10:52:30 PM
This is exactly what I was referring to. The first tank is always sort of unpredictable in terms of tuning (ie, dead-sticks).

Starting trouble is another issue anwar, may be due to flooded engine bcoz the engine is running rich.

gauravag · October 25, 2010, 10:22:14 AM

Thanks. Any hints to the pull-pull setup ? How taut should the wires be ? and what to do about the little slop wue to the amplication of the servo play, caused by the long horn on the servo ?

Also, to secure the ends of cables should i put a drop of epoxy on them ?

gauravag · October 25, 2010, 11:02:27 AM

Also, any hints/tips on cowl installation ? Its got a huge inlet in the front, should i attempt to baffle it ? I wouldnt like the engine to over heat !

gauravag · October 25, 2010, 12:15:03 PM

One more quick question. Should i attempt to mount the tank close to CG ? or does it need to be close to the engine ?

flatspin_king · October 26, 2010, 09:46:22 AM

hi gauravag,
congrats on the maiden. I would recommend using the standard tygon gas fuel line if you are not already doing so - but even this will eventually harden with exposure to fuel and you will have to replace it.
As for the pull - pull I as far as I understand it should not be drum tight or tight like a guitar string but tight enough that it makes a "thwak" sound when you pluck it - I dont know if this makes sense. btw a little slop in metal gear servos is a fact of life -just make sure you have enough grease on the gears so they dont wear out prematurely.
It is always a good idea to baffle the engine - there can be high pressure in the cowl which prevents adequate airflow over the engine despite the big opening - and air extraction is equally important -here is link which I found useful
http://www.prme.nl/forum/viewtopic.php?p=506#506

as for the tank ideally it should be as close to the cg as possible. The carburetors on gas engine have a built in pump -so the tank doesnt have to be close to the engine
cheers,
Nishad

flatspin_king · October 26, 2010, 10:21:03 AM

ps. I did not notice that you were using titanium gear servos - there should not be so much slop with titanium gears -if the plane is wagging its tail there is definitely too much slop in the set up.
it would be best to first determine the exact source of the slop -is it in the servo or the pull pull set up or both - then you can go with a smaller servo arm and compensate for the loss of throw either mechanically or by adjusting throws through your radio.

gauravag · October 26, 2010, 01:25:18 PM

Thanks Flatspin. I get it what you mean by the sound of the cable. not tight like a guitar string, but tight enough to make a low freq sound.

Will try to tweak this today and also replace the horn on the rudder with a smaller one to see the effect of it on the slop.

BTW I am going to do some work on the airplane this week. I got my SDSHobby parcel today and i have got a smoke muffler, lots of tubing, spinner, opto gas kill switch, etc etc.

My plan is to add a smoke system. I have a TME pump lying around and plan on using it.Will keep you posted with pictures and updates !

gauravag · October 27, 2010, 10:34:15 PM

I am thinking of putting the cowl back on, when flying next, this weekend.
Concerned about the huge opening in the front, and not sure if i should leave it like that or work on the baffling.

Harveer, since you have a similar Yak, please suggest if baffling is needed, or if it would be OK just the way it is.

Thanks !

Harveer · October 28, 2010, 01:05:47 AM

Quote from: gauravag on October 27, 2010, 10:34:15 PM

Harveer, since you have a similar Yak, please suggest if baffling is needed, or if it would be OK just the way it is.

Thanks !

There is no baffling in cowl. Some part of the head is out of cowl, can see in the pix. Thats all.

flatspin_king · October 28, 2010, 10:37:01 AM

Quote from: gauravag on October 26, 2010, 01:25:18 PM
My plan is to add a smoke system. I have a TME pump lying around and plan on using it.Will keep you posted with pictures and updates !

cool! need video with smoke on

gauravag · October 28, 2010, 10:43:36 AM

Lots of work being done on the airplane. Had to take out the fuel tank, cabling etc and redid it all.
Added an Opti-Kill switch, an RCExel tachometer ( reads off the ignition ) , installed the TME pump, added a 16 oz tank for smoke, added fuel dots I got from SDSHobby, and also smoke muffler.
Also mounted all switches on the side of the fuse, opposite the exhaust for easy accessability.

Only thing now that I do not have is a big 4.8V battery pack for ignition. The one i have is only 1000mah and I need more.

Next task is to enlarge openings in the cowl more, and also to make a hole in the cowl to help access the needles.

Got a spinner too, and will mount it on the plane after the cowl.

SDShobby rocks. Got real good stuff from them at pretty reasonable prices. Quality of spinner is amazing, the smoke muffler is also too good - for < $20 .

Plan is to fly again this weekend with all enhancements.
For smoke, planning to use 50% kerosene - 50% diesel mix.

Still lots of work to be done, will post pictures later today.
Thanks

gauravag · October 30, 2010, 11:26:29 AM

Spent nearly the whole week trying to puti onthe smoke system, but given up the hope now. Will atempt it sometime later. Problem was with the smoke tanbk mounting. There wasnt anough space within the fuse to mount both tanks and I tried all options and it didnt work. THe only optionremaining is to cut the covering and install the tank within the canister tunnel below the main tank.

Will work on that next week.

Flew the plane today . I am addicted to gas now, for sure. Though the plane snaps on giving even 60% elevator so thats the only bad tendency i have found so far. Or is it usual for big planes to snap out ? I never had this in my other planes.

flatspin_king · October 30, 2010, 12:19:37 PM

cant you get a smaller tank for smoke? As for snapping have you already put some negative expo on your control surfaces?

bmanoj2 · October 30, 2010, 06:37:21 PM

Quote from: gauravag on October 30, 2010, 11:26:29 AM
Though the plane snaps on giving even 60% elevator so thats the only bad tendency i have found so far. Or is it usual for big planes to snap out ? I never had this in my other planes.

Did you adjusted the expo settings or just reduced the travel to 60% ?.
Negative exponential (-) decreases initial servo movement. Positive exponential (+) increases initial movement. (For Futaba).

prabu85 · February 07, 2018, 05:27:10 PM

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Regards,
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prabu85 · June 29, 2018, 01:41:17 PM

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Quote from: prabu85 on February 07, 2018, 05:27:10 PM
Yak 55 Kit For sale https://drive.google.com/open?id=1uAyqOlbLtibr_eQb4w0TWvqBW_T9cWXM

Laser cut Wooden kit.

Regards,
Prabu

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