yak 55 32" hobby craft foamboard build - RC Groups
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Sep 05, 2017, 07:34 AM
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Build Log

yak 55 32" hobby craft foamboard build


EDIT - Realisd i posted this in the wrong forum, ive requested to have it moved to the right forum

Got round to starting my foam version of the yak 55 this time, the way it was meant to be and not out of super heavy cardboard. Thsi is what i should have done before trying to make a paper weight version. I weighed all the pieces after i cut them out and it came to 150g. 200g with battery, then add the motor 25g plus servos and esc its probably going to be around 250g. heavy considering that i think most people are around 190g but i am running a 3s 850 setup instead of 2s 300mah. The motor is advertised to produce 400+g thrust so should be fine, it may just hover at higher throttle

Fiting the wing into the fuselage. the original plans dont have marks on where to cut slots for the wing and elevator lik in the build guide. there i one plan that has better marks but its not tiled. tried to tile it but it made far too many pages and i thought the original plan tiling was more sensible and easier to use.

Also i used 5mm foam, so had to adjust the guide which is for 9mm foam. rather than cutting the fuselage in half like the plans seem to suggest, i measured the wing from front to back and cut a slot also taking into account 5mm sizing. Did the same for the elevator so its a nice snug fit


All Pieces cut out, hinges done. only thing needing to do before glueing is cut out servo holes.


In my cardboard version i used gaffe tape for the hinges, not the greatest. i looked up several different ways of doing it but was never happy with any of the tape methods. I then came across a method from the modular building thread that is really clean and produces a perfect hing. By leaving the backing paper on the foamboard (removing isnt an option on mine becuase its glued on very well) you can use the paper as a hinge. Just cut through only the foam leaving the paper intact and then cut a 45 degree angle from the control surface.
The first aileron 45 cut was really ragged but it worked well, the 2nd aileron is better. My elevator hinge isnt much better but it was harder to cut. Still the hing action is miles better than when i tried tape and it keeps the control surface perfectly inline with the wing. The rudder obviously cant be done this was as its a seperate peice (hmmm thinking back with a bit of carefull planning i could have incorporated the rudder into the fusolage so i could hafve that same hing) ill just use the welders glue method for that one.


Getting the plans all together on the floor is usually not the best idea, this guy always seems to want to sit on something that is on the floor, if a book was the only thing on the floor he would sit on it instead of the massive floor with super thick soft carpet


Ive ordered 12 amp ESC with 2amp BEC weighs 11g not too bad. Ill save a little weight by wiring the motor directly no using the bullet connectors.. Also 2 8x4 props and some JST male pigtails.
Last edited by bazsound; Sep 05, 2017 at 10:26 AM.
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Sep 07, 2017, 04:04 PM
Registered User
Got the plane finished up today and guess what.. its tail heavy!!!! even with a 50g 3s battery as far forward as you can with a battery box build with spare foam, and then a 10g weight on the opposite side at the front. Looks to be balancing about an inch behind the CG mark.

As long as it holds of rain for a bit hopefully give it a test flight.

Still waiting on this being moved to the correct forum
Sep 07, 2017, 04:47 PM
Hot glue held together by foam
balsa or carbon's Avatar
Quote:
Originally Posted by bazsound
Still waiting on this being moved to the correct forum
Just abandon this thread and start a new thread in the forum you want .
Sep 08, 2017, 04:13 AM
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Quote:
Originally Posted by balsa or carbon
Just abandon this thread and start a new thread in the forum you want .
This is how mess is created, ive not had problems having threads moved before.
Sep 13, 2017, 06:11 AM
Registered User
Smoked ESC and motor today, i guess its just too much weight for that little 7amp motor

https://hobbyking.com/en_us/fc-28-22...er-1200kv.html


This looks like it will do the job :-)
Sep 13, 2017, 04:51 PM
Hot glue held together by foam
balsa or carbon's Avatar
Quote:
Originally Posted by bazsound
Smoked ESC and motor today, i guess its just too much weight for that little 7amp motor
The only load on a motor is the prop .... so too much PROP will smoke a motor/ESC , not too much weight . A plane that is too heavy for the thrust produced by a motor/prop/ESC/battery simply will not move or become/remain airborne .
Sep 13, 2017, 05:30 PM
Registered User
Quote:
Originally Posted by balsa or carbon
The only load on a motor is the prop .... so too much PROP will smoke a motor/ESC , not too much weight . A plane that is too heavy for the thrust produced by a motor/prop/ESC/battery simply will not move or become/remain airborne .
yeah after some reading/hep over at the power systems thread, i realised that id over proped it by a huge amount, I had asked in the yak 55 thread if 3s was ok. some one said they ran thers on 3s but left out the vital informat of if you up a cell you need to reduce prop size. total current draw for the 8x4 on 3s could hit 15amps. i think it was the windings failing though that killed the ESC, as the motor just stopped and it wasnt until after i landed that the ESC blew up. either that or it shorted out on the wet grass?


anyway got a bigger motor and ESC conming which has the advantage of moving the balance forward. This time though im gonna mount it better and make sure i can add down thurst ( it looked like i actually had maybe a degree of up)

Ive been reading that some profile planes need some down thrust or they are pretty unstable and wobble about, that kind of describes how mine was flying, with the wing rocking, especially when going fast,er and when you were flying with the wind and turned round to go into the wind it had a habbit of suddenly rolling to knife edge.

I couldnt mount the motor to be adjustable because i had loctited it into the motor mount (no way it was coming out) whcih meant i couldnt screw the mount into the fire wall so used epoxy. Held the motor solid but no angle adjustment...

BTW yay my thread moved
Sep 13, 2017, 11:55 PM
Registered User
Extreme Sports's Avatar
That is the HK equivalent of the Emax motor I mentioned. I've found it matches best with a 8x6 prop on 3S. If you are at sea level, just check the motor temp frequently - as mentioned before I can get away with slight over-propping due to the altitude I fly at.

There is an extensive thread on rewinding that motor that also highlights its weaknesses: https://www.rcgroups.com/forums/show...-Rewind-Thread

No need to read it all - the key thing to know is that the little grub screws tend to vibrate loose, the motor twists and breaks the wires. Here are your options, from easiest to hardest (but best):
1) Loctite or use wood glue to stop the grub screws coming loose
2) Replace the grubs with 3mm x 8mm hex screws and loctite in - the hex screws are easier to fasten properly
3) Drill and tap a 3rd locking hole at 90 degrees to the others, and then apply (2). With the locking screws at 180 degrees (as in 1 and 2), the bearing housing is held in place by the tips of the screws, so is not very solid. With the screws at 90 degrees, the bearing tube is pushed hard against the mounting tube and therefore can move less. Hope this makes sense.

You will see immediately that the fit of the motor into the mount is not as tight as with the HXT motor, hence the need for remedial actions.

Hope this works out.

PS: I built a depron version of the Yak (36"). Worked best with motor pointing straight ahead - no need for thrust angle adjustments
PS2: Wet grass should not cause a short. These motors (but not the ESC) can run fully submerged in water.
Sep 14, 2017, 05:19 AM
Registered User
Quote:
Originally Posted by Extreme Sports
That is the HK equivalent of the Emax motor I mentioned. I've found it matches best with a 8x6 prop on 3S. If you are at sea level, just check the motor temp frequently - as mentioned before I can get away with slight over-propping due to the altitude I fly at.

There is an extensive thread on rewinding that motor that also highlights its weaknesses: https://www.rcgroups.com/forums/show...-Rewind-Thread

No need to read it all - the key thing to know is that the little grub screws tend to vibrate loose, the motor twists and breaks the wires. Here are your options, from easiest to hardest (but best):
1) Loctite or use wood glue to stop the grub screws coming loose
2) Replace the grubs with 3mm x 8mm hex screws and loctite in - the hex screws are easier to fasten properly
3) Drill and tap a 3rd locking hole at 90 degrees to the others, and then apply (2). With the locking screws at 180 degrees (as in 1 and 2), the bearing housing is held in place by the tips of the screws, so is not very solid. With the screws at 90 degrees, the bearing tube is pushed hard against the mounting tube and therefore can move less. Hope this makes sense.

You will see immediately that the fit of the motor into the mount is not as tight as with the HXT motor, hence the need for remedial actions.

Hope this works out.

PS: I built a depron version of the Yak (36"). Worked best with motor pointing straight ahead - no need for thrust angle adjustments
PS2: Wet grass should not cause a short. These motors (but not the ESC) can run fully submerged in water.
I had that issue with the motor i have at the moment, i didnt have the grub screws tight enough, although they can be tightened enough (aswell as loctite) with a good hex driver but i wasnt convinved and loctited the motor into the mount with red loctite. Now if you dont ever want to get your motor out of the mount thats fine. I later wanted to get th e motor out the mount to remount it with washers for thrust angle, nope nochance is it coming out...... Even tried a mini blotorch. cant get the red loctite to give up.

I may rewind the motor, as i can still get to the c clip
Sep 14, 2017, 08:43 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
I have run those motors (the 'new' 2822) loads of times, a FB gave me 4 with ESC's 'because he didn't need/ want them any more'!!!
I run them on the cheap 9X5 Gemfan DD props :-

https://www.banggood.com/10pcs-Gemfa...l?rmmds=search

I have used the 10" slow-fly props as well, work OK but current draw is up a bit.

Really good solid honest work horse.

Paul
Sep 14, 2017, 09:50 AM
Registered User
Quote:
Originally Posted by PaulB
I have run those motors (the 'new' 2822) loads of times, a FB gave me 4 with ESC's 'because he didn't need/ want them any more'!!!
I run them on the cheap 9X5 Gemfan DD props :-

https://www.banggood.com/10pcs-Gemfa...l?rmmds=search

I have used the 10" slow-fly props as well, work OK but current draw is up a bit.

Really good solid honest work horse.

Paul
Good stuff i may grab some of those props . worth waiting for 10 props at that price... I was payihng more than that for 1 or 2. Just need to be carefull i dont overload by battery wires, being that they are JSTS
Sep 14, 2017, 10:27 AM
Kimbers Keeper.
BHOFM's Avatar
Blue thread lock only on models.

And I know your cardboard plane was too heavy, you can build too light. I have a plane that
is a copy of a depron model, built in DTF, about 50% heavier than the original, and flies much
better.
Sep 14, 2017, 11:05 AM
Registered User
Quote:
Originally Posted by BHOFM
Blue thread lock only on models.

And I know your cardboard plane was too heavy, you can build too light. I have a plane that
is a copy of a depron model, built in DTF, about 50% heavier than the original, and flies much
better.
mines actually flew surprsiing well although it had a tendancy to knife edge turning back into the wind but i hadnt had time to fine tune thrust or anyuthing , i think i actually had a degree of upthrust which may have been upsetting it.

balance was right on the the CG mark if you carefull got it into a harier and turned into the wind it happily sat drifting really slow, it did want to constantly nose up thougyh...
Sep 15, 2017, 02:10 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Quote:
Originally Posted by BHOFM
Blue thread lock only on models.
Actually (not wanting to derail so just for info, not discussion)......

https://www.rcgroups.com/forums/show...0&postcount=15
Sep 15, 2017, 02:17 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
The props are a good deal, I ordered a bag of all of them from 5" to 11" last year and when I get down to around 3 - 4 I order a new bag. They are the DD style and are slightly stiffer than SF (SlowFly), I had a few problems with vibration with SF props and got the feeling that I was loosing power with them due to flexing.

The previous owner of my motors had stripped a couple of the threads on the mounts but it was an easy job to drill and tap new holes. Purple Loctite and decent tools and you won't have a problem.

Paul


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