HANGER 9 * * *SUNDOWNER* * * Aircraft Review Page 2

Here is the Sundowner fully charged and ready to fly. My BME 50 only has some bench-run time and  is cranking out 9790 RPM on an APC 16x14 prop. That's about 129 miles per hour on a level flight. Don't let the MPH number fool you! When this engine un-loads in the air it will sling-shot closer to 140/150 MPH. I installed inlet grills to divert some of the air-flow. The cylinder is in the inverted position so it has more than enough cooling.. I also black powder coated the muffler so it wouldn't be too ugly. One thing I really don't care for, are those bulky wheel pants. After looking at THIS photo I decided to replace them with more aerodynamic, sleeker looking wheel pants. Rummaging through my collection of stuff, I found a nice set from my Pitts Monster.The fit perfectly!    

The new wheel pants are just a lot cleaner looking having a lower profile and more aerodynamic.

My Sundowner is equiped with an on-board flight recorder made by WINGED SHADOW SYSTEMS . This particular unit only records peak (air speed) miles per hour.

MAIDEN FLIGHT:
My Sundowner finally got flown! It was a very windy day and the Sundowner handled it good. The aircraft got airborn quickly at 1/3rd throttle not needing any rudder correction. Once up high enough I let go of the controls to see what it needed in trim. Only slight right aileron. I flew at 1/2 throttle for about 10 minutes getting acclaimated with it. The aircraft is reasonably stable. The factory settings are too mushy for me, so I chopped the throttle and floated it in. It lands nice, but it does take a lot of runway to get it on the ground. I bumped the controls to maximum travel and took-off again. This time it flew more like I had hoped. I went to full throttle and flew it for 11 minutes. I did pylon laps, loops, rolls, and a few other aerobatics to see what it's capable of. Not too bad!

My only disappointment is the speed! My flight recorder registered 107.8 MPH. That sucks. I was hoping for at least 125 MPH anyway. But in doing the math, that's really all it will do with the current prop. I switched to a higher pitch prop, but a narrow type. This recorded 100.6 MPH. OOPS, that won't work. It will take a "normal" width prop to get it up to speed. I have ordered an assortment of props. IT WILL GO FAST, sooner or later!

All in all, the Sundowner flies really great! With it being a typical pylon plane, it does take a lot of runway to get it down with the engine running. I will be very happy with it once I get some good speed going.

My BME 50 is running flawless. It starts easy, and purrs at any speed. The only thing that needs attention is the exhaust. The stock muffler creates a lot of backpressure at higher RPM's. To correct this, I made a header that has a gentile curve in it. This should allow the engine to breathe better at peak RPM. After replacing the stock muffler with a straight pipe, my speed jumped up to 123.9 MPH. Then I went to an MTW canister muffler, the engine runs MUCH BETTER, yielding a "calculated" speed of 148.9 MPH.   

IMPORTANT  RECOMMENDATIONS for big gas ENGINES!

(A) Use high-quality pinned hinges instead of CA hinges. Great Planes offers a nice pinned hinge that will directly replace CA type hinges.

(B) Re-enforce the firewall. Either pin it or use screws. You can also fiberglass it as well.

(C) Use better quality servos. Not for power, but resistance to airframe vibration.

(D) Use thread lock on all screws without exception.

In order to get top performance from a larger gas engine, you will have to PROP it for SPEED. This is something you won't be accustomed to with your engine. The idea it to take your prop PITCH up to maximum MPH. So in essence,  you will go way down in prop DIAMETER and way up in PITCH. I use an APC 16x14 prop on my BME 50. This provides excellent speed, and good thrust. You will have to experiment...

One thing to consider... The exhaust systems "normally" available for big gassers are not too good for speed. The back-pressure is way too high for top RPM. STOCK and PITTS style mufflers are totally useless. Look for either a TUNED PIPE or a CANISTER muffler for your engine! I went with a canister muffler, and it's works GREAT!

Don't be afraid of spinning your gasser up! Most ALL USA made engines can easily handle 12,000 RPM without adverse effects.

A WORD OF CAUTION:
This aircraft flies much faster than it "APPEARS", because of its size. Make absolutely sure your aircraft and radio gear is in PERFECT operating order. Your airplane will be traveling at more than 185 feet per second! A lot can go wrong in a second.  

FLIGHT REVIEW:
I found the Sundowner to be very easy to fly. It takes off straight not needing any rudder correction.  The factory recommended CG is OK, but the recommended control throws are too soft for me so, I maxed them out. It's much better...  The Sundowner tracks perfectly at any speed, but watch your elevator input at low speed. It can and will snap if you're too slow. It will perform all basic maneuvers surprizingly well! But stay away from flat spins, it takes a long time to recover. Speed isn't of any concern... it's made to go fast and it won't flutter. Because of its size, it doesn't look or act like it's going un-conrtrollably fast. I had one (un-planned) dead-stick landing. The Sundowner simply glided home and stopped at my feet. I tested several landing methods and found that chopping the throttle to full idle  on the down-wind leg and coasting home works best. All things considered, this is a very nice model. Don't get your hopes up TOO HIGH regarding speed. Even with a BME 50cc there's a frictional limit as to how fast it will fly.

BEST FLIGHT:
After many flights and recording speeds from 118 to about 125 MPH, I installed a full-length tuned pipe on the BME. This propelled the Sundowner to 137 MPH to 152.9 MPH in a high bank-turn. That's some serious go-fast. I had pondered tuning it back down, but I hate giving up the performance! :

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