Pilot RC 25% Sbach 342 ( 30cc )

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Pilot RC 25% Sbach 342 ( 30cc )

Postby DonEmmel » Fri Feb 24, 2012 11:20 pm

Here is the final build pic of a Pilot RC 25% scale Sbach 342 with a DLE-30. I'll post some build pics once the thread is approved. The build for this kit was much easier than the 30cc Extra 300 from Extreme Flight RC that I built last year (and crashed). The installed cowl ring made for a really clean looking cowl mount. Since the kit was designed around the DLE-30 the weren't any issues with get the spacing right between the spinner and the cowl. The kit also came with a painted carbon fiber spinner that matches the trim scheme of the plane. The landing gear is carbon fiber with aluminum hubs and rubber tires. The ailerons and elevators came installed so the only thing I had to mount was the rudder. It came with control horns but I preferred the CNC aluminum control horns from SWB I bought for the ill-fated Extra 300. It also came with tygon fuel line and a fuel dot but I used the qwik fill fuel dot I bought for the Extra. The AUW weight is 12 lbs which gives it a wing loading of about 27.5 oz/ft. The extra weight seems to be used to provide a pretty sturdy model that should take a pretty good beating. It seems a tab heavy to me but that is partially due to the 2 Rx batteries and 1 ignition battery I used. I could have used a single high capacity battery but preferred this setup. The canister muffler also adds a good bit of extra weight but it is needed. The DLE-30 should give me close to 18 lbs of thrust so it will have some get up and go! I've got my own Radio Shack db meter and I'm right at 95db with the canister muffler. It is crazy loud w/o it. The ARF was $425 delivered. The Extra 300, which was a tiny bit bigger, was $550 delivered and it had cheap aluminum landing gear, no spinner, no cowl ring, and cheap wheels and tires. I'm hoping the extra bright trim scheme shows up well even on cloudy days.

Finished.jpg
Finished...
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby DonEmmel » Sun Feb 26, 2012 12:05 am

One of the things I really liked about this ARF was the thought put into packing the parts. Instead of a bag of screws, washers, and nuts all mixed together they had individual pouches of parts related to a task in a long strip. The attached pic shows at least part of the strip of parts. There was no confusion as to which pieces of hardware went together. The titanium turnbuckles came with a special wrench for adjusting them. This was another nice touch. Sadly I lost it during the build.
Attachments
unpack2.jpg
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby DonEmmel » Fri Mar 09, 2012 5:49 pm

I (successfully?) maidened the Sbach last weekend. She came down in the same condition she went up in so I consider it a success. There was a little bit of excitement during the maiden flight though. The CG wass off a tad making it a little tail heavy. While attempting the adjust the elevator trim I accidentally hit the ignition kill switch. This is not recommended during a maiden flight! :) I learned that this plane has much more "float" to it than I expected. Trying to keep it level when the trim\CG was off was a bit tough on touchdown. She came down right where I wanted on the runway....and promptly bounced back up a good 10 feet or so. I thought for sure it was going to stall and drop like a rock. She ended up floating another 200ft and gently touching down in the field next to the runway (not RCMB). There wasn't a scratch on her, just a bit of mud. Whew! Quite the exciting maiden. The receiver batteries have been moved forward several inches and the ignition kill switch is now on the DX8 knob. This should make it pretty hard to accidentally kill the engine in flight. I left the elevator trim alone hoping the CG shift will level out her flight characteristics. The weather looks good for Sunday so hopefully I'll get in flight #2.
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby mBagley » Sun Mar 11, 2012 8:40 pm

Nice Job on showing the building and test flying your new plane. Hope your work out the CG issue !!
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby DonEmmel » Mon Mar 12, 2012 10:57 am

Thanks. I've got some pics from various stages of the build but there isn't much traffic on here yet so I haven't posted them.
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby DonEmmel » Mon Mar 26, 2012 8:01 pm

It's been a real pain getting a linear throttle curve on this DLE-30. There is a diagram on http://www.troybuiltmodels.com showing how to get it set right using servo arms and carb arms of a very specific length. The length of the throttle arm on my carb was too short which caused way too much sensitivity at low throttle. I was getting nearly mid-throttle rpm's with the throttle stick barely above idle. This made for tricky landings since I couldn't do proper throttle management. Once the mechanical setup was fixed it was pretty close. I still needed to use the throttle curve feature on my DX8 to get it right. Hopefully I'll get to test it out sometime this week since I'm off all week. Stupid weather :x
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby wolfetrac » Sat Apr 14, 2012 10:40 pm

Nice post, I built a seagul models extra 260 last summer with a DLE 30. It was me and my son's first gasser. At first, the engine would not run right and kept missing bad especially at mid throttle and some at wide open throttle. Also the plane would take for ever to bleed off speed and would float in for super long landings using all the RCMB runway and more. After a few weeks of turning screws, I took the carb appart, I could not see any visual problems. To make a long story short, it turned out the factory sparkplug was the cause of the engine issue but I still had the glide problem on landing. Everyone kept saying turn the idle down, turn the idle down! I had it as low as I could go and still the issue. Come to find out, the thrust angle was off causing the plane to pull downward hard at full throttle and want to lift at idle causing a noised upward glide very similar to being tail heavy. Now that was finally solved and we could land the thing. Next was the throttle issue with wide open throttle at 1/2 stick. We are also using a DX8 transmitter. I just added the longer throttle arm and a TBM muffler plug to get the noise down. The throttle works good now with the longer arm & transmitter throttle curve set. I had to totally retune the engine with the muffler plug installed. The noise level before the plug was 104 dcb and is noticably quieter now. It should be below 95 dcb now but I have not had a chance to check it. I only lost about 200 rpm wide open with the plug installed which is not bad at all. The DLE 30 makes tons of power.

Good luck and hope to see you at the field, Richard.....
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby DonEmmel » Wed Jun 20, 2012 11:27 am

I think I finally have the thrust and CG set right. The issue does appear to have been a thrust angle problem. The motor mounts were visibly angled down and were supposed to be straight. I kept thinking it was a CG problem but no matter how nose heavy I made it there were still problems landing it. A few shims seems to have fixed it. Now I need to figure out what is up with the motor. It sounds like the engine is fading in banked turns. I need to check the metal screen on the carb to see if it has gunk on it.
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Re: Pilot RC 25% Sbach 342 ( 30cc )

Postby marjoriee » Wed Jan 22, 2014 4:34 am

The AUW weight is 12 lbs which gives it a wing loading of about 27.5 oz/ft. The extra weight seems to be used to provide a pretty sturdy model that should take a pretty good beating. It seems a tab heavy to me but that is partially due to the 2 Rx batteries and 1 ignition battery I used. I could have used a single high capacity battery but preferred this setup
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