Pilot-RC 26% Yak 54

[Ramz]

Anybody have any experience with this plane? I just got mine a few days ago from Tony and I am very impressed so far. I am trying to get it under 10lbs RTF as I think it will really shine with a light wing loading. For the guys that do have this plane, what do you think of it so far? What is your setup and what is your AUW?

[Ramz]

Nobody has any experience with this plane?

[apriliamille]

hello
im looking at getting one of these or the extra for an electric project for my xmas present
would you mind letting me know what your ground clearance is for a prop so i can work on my calculations for a motor prop combo?

[Ramz]

It is approximately 12" from the middle of the crankshaft to the ground when the tail is at flying level. That is using 3.5" wheels.

[apriliamille]

thanks

[kce]

I have the 30% 50cc pilot yak. I have it a little tail heavy but it flys great. It is the quikest build ARF that i have ever built and i have completed many. It flys the best of any of my planes from the 50cc profile to the 35% yak and everything in between. With mild 3D throws (30 to 35 degrees) it will dance and fly so good you have to fly it to believe it and i have never said that about any other aircraft in my 15+ years of flying. I can keep this plane in a 150 foot square in front of me and do eveything possible and the plane just floats around (only 15 and a half pounds). You can flip it on it's back with only a small amout of power and full up elevator and it will fall flat, completly horizontal until you add power and it will then jump up into a torque roll. It is nice and will put a smile on your face.

[Ramz]

Something that I did take notice of when I assembled this plane was the weight of every component that was used. I was very weight conscious and chose lightweight components. I used a different fuel tank, light wheels, light axles, shortened all of the bolts, lightened the fuse, lightened the hatch, lighter fuel dot, lightened the tailwheel, etc. I also noticed that the left wing panel was 2.2oz heavier than the right wing panel!! The left wing with no hardware was 15.2oz and the right wing panel was 13.0oz. As a result i had to add 1.25oz to the right wing panel at the tip for it to balance. I also had to mount the battery and regulator on the right side for lateral balance. I think it will fly well....very impressed with the fit and finish and it looks like a very strong and rigid frame. Going to shoot for a maiden before the snow flys. If anybody is interested, I could list all of my lightening mods and all of the weights...

[Ramz]

As I mentioned earlier, my goal was go get the all up dry weight to 10lbs or less. So, here is my setup:

Hitec 5955's on all flight surfaces using the stock Hitec arms.
HS 81 for the the throttle
Rhino 20C 2150mah lipo for the ignition and the servos
AR7000 receiver
Flightpower 8amp failsafe regulator
Standard Futaba switch (grabbed it out of the junk pile... )
Wike RC Ignition Battery Eliminator
Lightweight 3" Hobby City foam wheels
MPI 3/16 Titanium axles
12oz juice bottle for the fuel tank in conjunction with the Sullivan aluminum stopper kit
Hangar 9 fuel dot
JXF 19 x 8 prop
Used all of the supplied hardware except the servo control horns.

This is your typical ARF so their's nothing special about what goes where and such but like I mentioned, I wanted to keep it as light as possible (short of tearing the airframe apart). Here are some of the weights of the bare airframe components before lightening:

bare fuselage - 28.3oz

bare hatch - 7.6oz

left horizontal stab - 2.59oz

right horizontal stab - 2.7oz

rudder - 2.32oz

left wing - 15.2oz

right wing - 13.0oz (big difference in the 2 wings - had to add 1.5oz to the right wing in order to achieve a proper lateral balance)

carbon landing gear - 3.14oz

carbon wing tube - 2.8oz

carbon tail wheel assembly - .99oz

carbon tail tube - 0.65oz

stock axles - 0.76oz each with collars

stock wheels - 1.44oz each

stock fuel tank - 3.15oz

wheel pants - 1.67oz each

spinner - 1.85oz

cowl (uncut) - 8.2oz

As an aside, I measured the complete DL30 (ignition, muffler, standoffs, bolts, etc) and it came out to 41oz even.

[Ramz]

The first part of the diet consisted of an overweight fuselage and a dremel with a sanding drum. After about 2 hours work, I managed to drop the fuselage from 28.3oz to 25.8 oz...a savings of 2.5oz. Doesn't sound like much but that's about 9% of the total weight....that is fairly significant in my books. You can see in the pictures where i dremeled out the motorbox sides, the firewall, motorbox bottom, the F1 former, etc. It's hard to tell but i did take a bit out of the landing gear plate and around the top of the fuselage where the hatch sits.

Next was the hatch. The stock weight of the hatch was 7.6oz. After removing all of the foam and plywood from the bottom where the pilot bust normally would mount, I managed to bring it down to a final weight of 6.28oz...that's a savings of 1.3oz....nearly 17%.

Their wasn't really much I could do with the wings so I just left them stock. Same goes for the rudder and the stabs.

One thing I did do that took a fair bit of time was to cut off all of the bolts that were too long. The cowl bolts were about 12mm too long so after doing this to all the bolts, the savings start to add up. I didn't bother weighing the bolts before and after being cut.

[Ramz]

The bone stock tailwheel assembly came in at 0.99oz. After some cutting and creative MacGyvering, I managed to get it down to .75oz. Instead of using 2 wheel collars (one on each side of the tailwheel), I opted to toss the wheel collars and solder a washer onto the axle. This also allowed me to cut off the remaining axle to further reduce the weight. The CF bracket came with 3 screw holes on the top however I opted to only use 2 of the holes, therefore I was able to cut off about 1/2" of the bracket. The rubber tailwheel comes in at 5.6 grams but I have some 1.5 gram tailwheels in the mail that I am going to try out from Hobby City. The tailwheel currently sits at 0.75oz..a savings of 0.25oz or 25%.

The stock steel axles, while plenty strong, were a bit on the porky side at 0.76oz each (with both wheel collars). After looking around for a lighter axle, I came across the MPI titanium alloy axles. For 16$ they were worth a shot. They claim they are half the weight of stock 3/16 axles and they were right...the titanium axles came in at 0.36oz....that's a savings of 0.4 oz per axle x 2 = 0.8oz or 53%. Rather than use wheel collars, they have grooves cut around the diameter of the axle that use a C clip...interesting. 2 flights and some high speed taxiing and no departed wheels yet.

[Ramz]

The stock 3" wheels are of very high quality with decent rubber and a nice machined aluminum hub.....however they had to go as they came in at 1.44oz each. Bolt on some 3" hobby city foam specials (.51oz each) and you come up with a total savings of 1.86oz or 76%.....and they were only 2$ each!!

I opted to not bother with the wheel pants although they do seem like a very well finished, rugged pant. They came in at 1.67oz each with no blind nuts of mounting screws.....savings of 3.34oz.

Same goes for the stock carbon spinner....savings of 1.85oz.

Next...the fuel tank. After weighing the stock tank that came with the kit and reading on Flying Giants about some of the guys using pop bottle as light weight fuel tanks, I decided to give it a try. So, after fiding an ideal tank at my local sobey's, here is what I came up with. (see above pictures) It is 12oz juice bottle that is perfect as it is square in shape and very light. I also opted to go with the Sullivan HD aluminum stopper as I wanted to make sure this thing work work out ok...that seems to be the popular setup among the guys on the other boards. The stock tank, ready to go came in at a hefty 3.15oz however my custom juice bottle tank came in at 1.75oz....that's a savings of 1.4oz or 44%. Also, the bare bones stock tank came at 1.94oz while the bare bones juice bottle with the lid came in at 0.99oz....basically half the weight. Kinda makes me wonder why the ARF manufacturer's continue to supply the "traditional" rc type fuel tank.

[Ramz]

Next on the chopping block was the battery. I used a 20C 2150mah Rhino 2S from Hobby City. It cost 8$ so you can't really go wrong with that. The stock battery came with 10 gauge wire and a balancing tab. I opted to lose the balancing tab and the 10 gauge wire in favor of some lighter wire to see how much weight I could drop. The stock battery weight was 4.12oz and the modified battery weight came in at 3.45oz...that's a savings of 0.67oz or 16%.

Even the switch was chosen to be as light as possible. I also chose to use a failsafe Flightpower regulator to power my servos and receiver and IBE. The Flightpower reg was chosen becuase if it failsafe so if the switch fails (goes open) then the reg will default to "on". Usually I use atleast one JR HD switch however at 1oz each, the JR switches aern't the lightest. The stock Futaba switch came in at 0.385oz however after modifying the switch to work with the failsafe plug of the regualtor, the end result was a switch with an auw of 0.25oz....that's a savings of not a whole lot...but 0.135oz is better than nothing. If compared to a HD switch, the savings are even more evident.

Pilot supplies a seperate throttle servo mount made out of lite ply that weighs 0.25oz. The typical standard servo tips the scales at 1.5oz. Rather than use the standard servo and mount, I opted to build my own balsa servo mount on the top of the motorbox and use a HS 81 for the throttle. The HS81 comes in at .58oz. That's a savings of 1.17oz over a typical stock setup. Every ounce counts.

[Ramz]

Pilot supplies a nice offset rudder servo control horn that seems very robust and solid. I had an offset SWB aluminum 3" arm lying around so I figured i would weigh the 2 and see how they compare. Using the Hitec HD round servo horn and the supplied rudder servo horn, they came up to .56 oz . The SWB aluminum arm came out at 0.16oz . Needless to say, I went with the aluminum arm. That's a savings of 0.4oz or 71% over the typical stock setup. I also opted to use the Hitec HD servo arms on all the other surfaces as these too were much lighter than the supplied servo control arms for the ailerons and elevators. (didn't measure those weights so i'll leave them out)

Finally, the typical ignition power setup consists of a seperate battery, seperate regulator and an optical kill or some sort of cutoff device. What I decided to do was use this little gizmo from Troy Built...it's called the Ignition Battery Eliminator (See last picture). Basically, it draws power from a spare slot on your receiver to power your ignition however at the same time, it acts as an electronic kill so that you can cut the power to the ignition via a switch on your transmitter. The IBE has filters to stop "most" of the interference from the ignition from getting back into receiver. While not as good as an optical kill, it does eliminate the need for the above mentioned items. Range checks fine and works exactly as it should. The typical ignition powersetup comes in around 5oz. The IBE comes in at .075oz. That's a savings of 4.25oz and it costs less than a ignition reg, optical kill and battery. The downfall is that I will probably only get 3 flights or so before I will have to either recharge my battery or swap it for a fresh battery. Also, the optical kill is a better method of eliminating interference from the ignition getting back to the receiver. So far, so good.

[Ramz]

So when you add it all up, that's conservatively a total savings of, at a bare minimum, 20oz or 1.25lbsover the stock setup!! My goal was 10lbs but unfortunately I didn't quite make it....the measured final dry weight was 10lbs and 1oz....only 1oz over my target...but I had to add 1.5oz to the right wing tip to get the proper lateral balance....so I'm going to play my "Mulligan" card and say that I achieved my goal. If you consider Pilot RC's claimed weight of 168oz, that 20oz savings works out to about an over all 12% reduction of overall weight.
The total extra cost for the upgraded components (excluding the 50$ for the IBE) came out to about 40$...definately worth it in my opinion.

Judging from my measured weights, I have no idea how Pilot got a dry weight of 10.5lbs using all of the stock components....maybe I got a heavy airframe with an above average amount of dense wood. Regardless, the plane seems to fly great and I plan on setting it up as a IMAC practice plane and a weekend beater. I'll keep you guys posted as to how it holds up. Time to start the tuning now...thrust angles, mixes, etc.

[flymorerc]

Nice write up of all your modifications. Maybe Pilot-RC is watching and will take note. BTW, where did you get your plane? Troy Built Models will be carrying them shortly - I think TBM gets the flame coverings, while Chief Aircraft will get the straight line designs. I'm in favor of the flame design.

Please do keep us posted on how the 26% does with the DLE-30.

Keep up the good work.