logo
Thread Tools
This thread is privately moderated by Xpress.., who may elect to delete unwanted replies.
Old 07-10-2017, 11:33 AM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Discussion
The Pilot Yak Saga

I've had this airplane for about 2 years now and have grown very fond of it. I've made probably a dozen different changes to its internals to better its performance or improve upon other areas that were not assembled correctly. It has taught me how to really fly 3D with larger airplanes and as such, I refuse to let it die.

I've also managed to crash it probably half a dozen times

I've been fortunate enough to have crashed it in manners where it is rebuildable. This time, I had what I am certain is the engine overheating on me right at the worst possible moment- at the bottom of a waterfall. As I punched full throttle to climb back out the engine decided it had enough and dropped back on me. Truth be told I probably should not have been flying in 95F heat with 95% humidity, everybody was having power loss issues. If you're gonna play with fire you're bound to get burnt at some point.

This blog will document the repairs and changes I make to the airplane from this particular incident. This is what the airplane looked like the day I brought it home. It had roughly 15 flights on it so it was fairly new.



A club member happened to be filming the flight:

Remote control Airplane 107" Stunt Flying and Fail 7-8-2017 (4 min 21 sec)


I know the engine sounds a bit unhealthy but it has ran like this as long as I've owned it. It's really worn out compared to my new DA120.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message
Sign up now
to remove ads between posts
Old 07-10-2017, 11:57 AM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Yesterday I pulled the airplane out and got to work on cleaning and mending. First up, everybody with a Pilot airplane knows that the engine box has this "X" shaped cutout. Well after a number of crashes it finally gave out, so I decided to 'off' it with the dremel.





I cut out a new lid out of 1/8 ply and mounted the ignition to it. Before the ignition sat right ontop of the front lip of the motor box. Also pictured is the screws I put into the firewall to help reinforce it. Pilot has aluminum "L" brackets they give you to install behind the firewall to strengthen up the sides but I like to pin the firewall to give it more strength.



In these pictures you can also see that the top of the first former has been cut off, it got smashed in the crash and since the top section serves no structural support for anything on the airplane I decided that I would just cut it off. The holes for the cowl bolts and for the front canopy pins are all elongated from they ears of hard flying, I'll just fill them and redrill them.

The floor that the fuel tank sits on got some damage in the crash, the velcro straps securing the fuel tank pulled the plywood up underneath so I glued a section of 1/8 ply in place to reinforce the area. I'm considering replacing the fuel tank as it's probably 4 years old (internals have Viton, but it's completely sealed), it has some distortions in it as well. This is a Fiji tank with PSP cap and fittings.



Lastly, the airplane has been setup with a separate ignition pack. All of the airplanes I've put together thus far have not used a separate ignition pack since I prefer the simplicity of using a Tech Aero IBEC. I had one lying around so it went into the airplane and replaced a Fromeco 2600 LiIon, Fromeco Badger switch, and Secraft battery tray (battery tray was removed after the photo).



That's all for now. Right now it's mostly a waiting game while I wait for new parts to arrive. I will be mending the spats this week, currently they are held onto the gear legs by the White Rose axles clamping down on them through the hole but over time the wood inside of the spat wears out. I'm just going to drill the hole in the spa completely out and then mount the spat to the gear legs with some 3mm bolts and blind nuts (like every other airplane, ever). Also I think I'll replace the exhaust vent on the belly of the airplane with a new one and cut the vent holes for it. The cowl cutouts provide a roughly 1:3 intake:exit ratio based on my rough calculations as far as surface area goes, but it never hurts to have more than you need.
Xpress.. is offline Find More Posts by Xpress..
Last edited by Xpress..; 07-10-2017 at 12:58 PM.
Reply With Quote Quick reply to this message
Old 07-17-2017, 12:39 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Sorry to keep everyone in limbo, still waiting on Desert Aircraft to inspect the engine and issue me a repair quote. It has been there since last wednesday but as I understand this time of year is exceptionally busy for DA, just have to have patience (something I don't have ). Hoping the repair cost isn't too great, I'm waiting on DA first before I order new parts for the Yak.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message
Old 07-18-2017, 05:53 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Got a call back from Desert Aircraft today, was not wanting to hear the news they told me. The DA120 is in very bad shape and needs to be completely rebuilt, new crank, bearings, hub, pistons, cylinders, but at least the case and carb are in good shape

I'd say the engine has held up well for having something like close to 1000 flights on it (averaging 8-10 minutes a flight, that's something like 8000 hours!), hopefully with this rebuild it'll be good to go again for another 1000+ flights!

Since I got the repair quote on the engine I went ahead and ordered up the parts for the airplane, should hear back from Tony by tomorrow.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message
Old 07-21-2017, 01:49 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
DA120 is all back up to spec and will be returned to me sometime next week Since it's basically a brand new engine I have to break it all in again but at least it'll have all of its power back. All of the rest of the airplane parts are ordered up, just waiting on them to finish making them and ship them to me.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message
Old 07-24-2017, 02:57 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
2 new Falcon 28x9.5 propellers and a 4" carbon spinner. AND the DA120 showed up today too, freshly repaired and rebuilt from DA!

Today is literally Christmas in July!!
Xpress.. is offline Find More Posts by Xpress..
Last edited by Xpress..; 07-24-2017 at 06:04 PM.
Reply With Quote Quick reply to this message
Old 07-25-2017, 05:42 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Okay finally some forward progress on the airplane!!!

Engine was bolted in last night and mufflers bolted up. I used my method to re-mount the engine since it just had bolts running through the firewall with washers and t-nuts on the backside. I drilled out the bolt holes and installed some t-nuts in place, then installed the lock nuts on the backside to help lock the bolts in place and keep them from loosening.

I also tried my hand at polishing the mufflers a little bit to get rid of some of the grease and gunk, didn't turn out exactly perfect. I did shine up the tubes though so I'll take that. I didn't have any muffler gaskets on hand so out came the red RTV, I used a trick a friend of mine showed me:

Muffler installation tips (8 min 32 sec)


One I set the mufflers on the engine I let the RTV set up for about 45 minutes before tightening the bolts down. After all was said and done I bolted the prop on and mounted the ignition back to the motor box and called it a night

Facebook shows you what happened on this day in the past years, looks like it was exactly 2 years ago I bought this airplane off of a flying buddy. It's amazing how quickly time flies as you get older, why it seems like it was just yesterday that I was building my first 55" foamy and thinking about just how big that airplane was to me at that time.
Xpress.. is offline Find More Posts by Xpress..
Last edited by Xpress..; 07-26-2017 at 10:15 AM.
Reply With Quote Quick reply to this message
Old 08-03-2017, 04:43 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
More shop time last night. The Yak got a new fuel tank and tubing, and I opened up the exhaust vents on the belly to let even more air flow out of the airplane. Carb arm also got a slight bend in it to allow it to clear the muffler since the bolt head sticks out a bit, otherwise this baby is ready to fire up and then slap some new parts on.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message
Old 08-17-2017, 01:56 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Got the cowl, canopy, and rudder in the mail from Pilot RC today. Don't have time to work on the airplane this weekend but I will get started this coming Monday. Hoping to maiden the airplane the following Saturday and get some flight time in on the engine before packing the van up on Sunday 8/27 to leave for the TriCities Huckfest on Monday 8/29.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message
Old 09-06-2017, 12:17 PM
Xpress.. is offline
Find More Posts by Xpress..
Fully Sending It
Xpress..'s Avatar
United States, AZ, Yuma
Joined Mar 2008
2,934 Posts
Jumping to this past weekend, the Yak flew phenomenal as always and the DA120 is screaming on power. Baffling on the engine kept it cool even in the 100+ temps outside and it had no troubles with low and slow flying, only thing left to do now is get a tailwheel wire for positive ground steering and bolt the spats to the gear legs (instead of sandwiched between the axle thread).
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote Quick reply to this message


Quick Reply
Message:

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools