PART II- Hat Trick 1/2A Arrow Test Flights

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sgilkey
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PART II- Hat Trick 1/2A Arrow Test Flights

Post by sgilkey »

See my previous thread for the build-along for this plane, with two different wings. We have had the coldest, snowiest early-winter I can ever remember, with lots of snow on the ground and continuous single or low-double digit temps since T-giving. SO what happens in good ol' Michigan just in time for Christmas- a THAW of course. I looked out the window today, notice the ground is mostly bare and even more amazing, the wind has abated. It finally hits me- i can test fly the new Arrow! YEE HAW!

First flights were with the stock Arrow wing. HS81 on ail, 55 on elev and throttle, Big Mig .061r/c, stock Freedom head with one shim, 25% nitro/20% oil/50% castor fuel. 1 ounce film-can tank (which worked great but proved inadequate, only getting about 4-4:30 duration), 300 mah Nimh, HFS04MG Rx, 16.3 ounces (dry) RTF. Temps started at about 40 deg, by the time i was done it was 35, humid with periodic freezing drizzle/ice crystals.

Since I had shortened the tail moment by 4 inches, the first flights were to determine balance point- I started out conservative at 27.5% and gradually moved it back on subsequent flights. First flight the plane flew right out of my hand with a gentel underhand toss, very forgiving flier. i needn't have been concerned about balance as the factory-recommended 33% turned out just fine even with the shorter tail. The turning was amazingly tight with no bad habits, very stable down low just above the weeds (not at all too sensitive on pitch), negative g were also very good and as tight as pos g. Stalls were very forgiving and easy to see coming, no nasty snap. power-off glide is excellent with simple flare for landing at almost zero ground speed (since i demonstrated an amazing ability to hit the tiniest pile of snow on landing, i finally resorted to simply catching the plane on landing- very simple as it is so slow in glide and very stable). Plane will fly continuous tight turns/loops without stopping, a good pilot like Eric or Hat or Lee or others could cut their own streamer with this plane, I'm pretty sure. An exceptional pilot, such as for instance myself, could take it a step further and tie the streamer in a nice bow but since I did not think to bring streamer material I did not have a chance to prove my enormous ability. maybe next time.

Started out with an "old" APC 5.7x3. The current 5.7x3 looks much thinner and narrower than the "old" version, which is shaped more like the current APC 6x2. I wanted to see if there was any difference in these 5.7x3s. Engine was turning the old prop about 20.8k. Interestingly though the current 5.7x3 looks much thinner, it turned the same rpm and performance in the air was the same. Sadly on about the 8th or 9th flight the rod galled to the crankpin, this is an older pre-revlite engine that is well used so no telling how long it had been run, it was just as the tank was running dry so the mix was a little lean, maybe it was due to the cold weather affecting the oil viscoisity? oh well.

Changed to my only other Big Mig .061 i had on hand, a well-used u/c version. Used same head and one shim. Went back to the "old" 5.7x3 to get a baseline and tached 21.5. then flew the APC 6x2, taching 22.7 (estimate would have been about 22 on the r/c engine). The engine really sings in the air with this prop, straight-line speed is a bit slower, vertical is somewhat better (to my amazement the plane will climb straight up virtually without stopping with this prop, a modest but noticeable improvement over the 5.7x3) but surprisingly the turning was not as good, probably due to the lower speed. it will still turn continously, but not as tight as the 5.7x3.

Next tried the Grish soft white 5x3. Tached it but realized later i forgot to record the rpm, it was mid 24k range. No way to know what the r/c engine would have turned this but guess mid 23k. Straight-line speed was noticeably faster than the 6x2 and also faster than the 5.7x3 though not as dramatically. Vertical still good though not as good as 5.7x3 (still impressive though). continous tight turns still possible but if you keep flying 10 ft. diameter turns, after about 8 of them the speed is bleeding off and the tight turn can't be sustained.

Bottom line on props: 5.7x3 is best overall performer, 5x3 gives more exciting speed and still turns well, 6x2 gives great vertical and may keep the engine turning in a happy rpm range on those hot humid days. it also has good potential as a performance limiter. I'd give the nod to the 6x2 as the 2nd best prop so far performance-wise. But of course the beauty of the Grish soft prop is the potential for damage limitation in prop strikes..... (did not have a Grish 5x3 stiff black, nor any of their 5.5x3 to test). The proposed rpm limit of 20k could have been hit with my engines by using lower nitro and/or more head shims with the 5.7x3. With the 6x2, equivalent performance to the 5.7x3 will take at least 1k higher rpm. The rules as currently proposed have the same rpm limit for all props, but this is just a placeholder until we get more data, the 20k on 5.7x3 is the most solid baseline. other props need more testing on other engines and other atmospheric conditions and planes.

Next we changed the wing to the "Roid" pink-foam Clark-Y section (see build-along thread). THis is the simplified wing with no rod spars (only tape), slightly smaller area and lighter foam but a thicker section. All-up weight goes down .6 ounce with this wing to 15.6, though area goes down a bit too. Bottom line- this wing flies great too! TUrns are almost as tight as the stock Arrow wing, low-down flight is just as stable and forgiving. speed is about the same, maybe even slightly greater. only place this wing gives up much of anything is in negative g, it will pull neg g but not as well as the stock wing. The continous tight turns are almost as good as the stock wing, the smaller area probably offset somewhat by the lighter weight.

Brian flew several flights too, overall we put in at least 15 flights, maybe twenty. We were both astounded by the performance of the plane. It turns tighter than anything we have flown in Open B or SSC, and speeds seem about the same, maybe slightly slower than SSC (possibly an illusion due to the close-in flying). The ability to continously turn in a 10-15 foot circle is unmatched in anything we have flown before. Based on these flights we are both convinced for this class, more power and lighter weight are definitely not needed, even Brian (who likes the faster classes) felt that the performance was amazing and too high for what we are shooting for in a "limited" event. Of course these flights were without streamer, i'm sure performance will go down with a streamer on, did not think to bring one along to test this out to get a feel for how much.

Daylight ran out- next step will be to put 1.5 ounces of ballast on the plane and see how it flies at the proposed 18 ounce weight. While I'm sure it will degrade, I will be very surprised if it is anyting approaching unacceptable, based on these flights. Also need to try pulling a streamer.

Bottom line on the Arrow is it is a SWEET plane. Fast/easy to build, very easy to fly, stable and forgiving, with amazing turning and climbing performance. Brian and I were both smiling ear to ear when we were flying the plane and can't wait to try combat with them. With the closer-in flying with these small planes, it will be very exciting indeed!
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boiler
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Post by boiler »

Scott, be sure to take two different frequencies to the field so you can cut Brian.[:)] Just put 4 oz of ballast in his plane to level the field.[;)]
sgilkey
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Post by sgilkey »

naw Bob I don't need to cheat to beat Brian (though it's not beneath me to do so), i'm just gonna use my new "tie the streamer in a bow" maneuver to make my streamer too small to hit, plus it will amaze the opposition and while they are dazzled by my skills I will cut them two or three times. By the time they recover i will crash my plane to deny them the target. How's THAT for a strategy???
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Post by boiler »

Sorry Scott, my pathetic skills as a rc pilot cause me to miss too much fun by hitting the ground before the end of combat. I would rather taunt other pilots to get my streamer before I dirt nap.[;)] Besides that I don't think a bow or very short streamer would deter Brian. He would take a 2 inch streamer off your wing tip since you have to repair the planes.[:D]
Thaman
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Post by Thaman »

you was talking about cutting your own streamer i did just that the last time we flew i went up almost to a stall and fliped it over and caught the end of my streamer on my wing [8D] how is that for streamer defence[:D]
i will have to disagree with ya on the waight of the planes when you get in some wind we all kinda of noticed that it became hard to launch the heaver planes. and we watched the lighter planes climb right out. the wind was about 15 to 20 mph
sgilkey
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Post by sgilkey »

See my other thread for results with more weight AND less power. Planes launched as easily (probably more so) than my SSCs.
Thaman
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Post by Thaman »

alli can say is there was 6 of us and time after time the heaver ones did anything but a good launch but dont take my word for it ask the other 5 that was there
sgilkey
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Post by sgilkey »

I'm sure you're right and that downwind launches may be a challenge, as they can be with SSC, we'll certainly not want the class to go the way of so little power and so much weight that launches are difficult. It's something we'll have to monitor as we go along! 15-20 mph tailwind can be a challenge even with b and 2610 ships. all i can say is the plane with two different wings that i have been testing has launched and landed like a dream. but no 20 mph tailwind!
ZenManiac
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Post by ZenManiac »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by sgilkey</i>
<br />First flights were with the stock Arrow wing.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote"><font size="2">Scott,

What about the tail? ...I couldn't see in either write-up whether you used the stock Arrow elevator, or your flying stab. Or I could have missed it - many words, little brain. [;)]

These are great reports!</font id="size2">
sgilkey
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Post by sgilkey »

Dave, I did not have a chance to try the all-flying stab, all flights were with the stock tail but fuse rods shortened 4 inches.
ZenManiac
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Post by ZenManiac »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by sgilkey</i>
<br />Dave, I did not have a chance to try the all-flying stab, all flights were with the stock tail but fuse rods shortened 4 inches.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
<font size="2">Good to know, Scott. I'm just finishing up my Arrow - made the fuse mod that you suggested. Just waiting for ServoCity to deliver, and stuggling a bit getting my new AP Wasp running (maybe if I'd buy a Cox glow clip instead of my alligator clips...).

The rain's taken care of most of the snow, so maybe this weekend...</font id="size2">
sgilkey
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Post by sgilkey »

I got the Sullivan clip from Tower, and flipped the bottom contact over. it works great on my Norvel and Cox.
sgilkey
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Post by sgilkey »

I re-did the SUBJECTS of the three threads in this series so it might make more sense. I thought it would help to break it up but now I'm not so sure. PART I is the build phase. PART II is the first test flights phase without regard to rpm or weight restrictions, and testing of props. PART III is keeping the same prop but changing rpm and weight to test performance limits. Also testing of a Cox TD engine.
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