The flying monkeys got me...

Helis and fixed wing

AMA 957918
IRCHA 4345
AMA Intro Pilot Instructor

Sunday, June 8, 2014

Wasted day...

It was another Africa Hot day here in Biloxi-Gulfport. Swimming throughout the air is exhausting. It was a wasted day as I did more time futzing with the engine on the 30cc than flying.

Aidan and I got an earlyish start, getting to the field around 10-10:30 this morning. There were already four stalls filled. I brought Aidan's Alpha Sport 450, my Sbach 70 and my 30cc Sbach.

The 450 hates grass, being a tricycle gear plane the front wheel gets caught up and bends and/or the plane rolls head over heels left or right. The new wheel kept bending until bending it back snapped it off. Then the cog & control horn that steers the wheel cracked (the original did too, this was a MacGyver replacement). We did get a couple of flights, but the heat melted Aidan and he was done for the day.

I took the Sbach 70 up a couple of times, flew great, not much to say.

I also tried tuning the 4-cycle out of the 30cc Sbach. No one has managed to do that, and there have been some pretty savvy people who tried. One was Jason, who offered after watching me fuss with it today, that I need to examine the carb's petal valves... We (Kenny and Jason) feel whoever owned this engine when it was new might not have broken it in correctly. Jason wonders if the petal valves in the carb have warped. He's ordering me another one, will be here Wed. I could look, but having to got through removing the engine and then the carb then dis-assembling it, why not just replace it. This could be the answer to why it persistently won't tune out of 4-cycling. Well, today she dead-sticked on me. I didn't trust her and would not go to full idle during that particular test flight. I finally did when I had her positioned on a downwind leg, and she quit as I thought she might. Easy landing.

In tuning her Jason gave me the advice about the petal valves, but Jim had me increase the trim on the throttle on the DX8 from zero, where I was tuning her, to 50%. This allowed me to increase the endpoint on the throttle servo low end to 70%, and tune in a more reliable idle! Thanks guys!

As promised, pic of the vent system. I ended up with 4 oz in the tail to balance her! I finished the vent louvers with the baffle to generate low pressure over the louvers, covering the opening where the weights went in.


Sorry about the backlighting ruining the contrast, but you get the idea of how it looks from the side. I tightened up that cote.



After tightening up the cote and laying down some electric tape to clean up the edges. I used Dual-Lock velcro at the from end, and a tab under a shaped piece of ply under the Pirate sticker, held in place with Dual-Lock. It ain't going nowhere.



Put my AMA number on the baffle. Because I could. The baffle causes low pressure to form behind it, drawing in air through the fuse and louvers out of the plane, increasing air flow from the cowl openings all the way back. They are a PITA to make, but they are a quick manufacture.



You can see the near 45 deg angle of the louvers.

Tomorrow I may go fly again, maybe take a day off... Going to fly the 30cc as is until I get the replacement pump for the carb and replace that Wed night. I think I finally got her CG's out, but she may still be a smidge nose heavy.

No comments :

Post a Comment