Groeps-bouwverslagen en ervaringen: Medicine Man 60"

@peter den, eh, i have been many times to Holland. You are below sea level. Never flown there but I can imagine your good conditions... It's quite difficult for me to balance weight, lightness, penetration, etc., at my altitudes.
Paper covering is easy for me so I can change colors all the time in autobody paint shop.
 
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I don't think finding the right center of gravity is more difficult at higher altitudes. Only the airpressure is lower and thus the flying speed seems to be higher (although the physics behind this are not clear to me). That might play a psychological role in interpreting correct CG. You try to fly slower then nature (physics) wants at that altitude, and because of that you configure flying with relatively more up, and that demands a more forward CG.

Dirk
 
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@Dirk, yup you right. CG and MAC, yup. But once you account altitude of this here Himalayas.. all bets are off. Velocity and penetration have to be greater at higher altitudes. Professor Mark Drela has excellent reports on this. He told me of higher altitude technicals for my BUbble Dancer build. I've flown at 22,000 feet ASL. The bird was just 370 feet off the deck, but I could see she was struggling at low speeds. Had to switch to larger prop.
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Yup, I was waiting for HK towline mechanism. Instead they sent me APM 2.5 clone So All mu weight saving is now...
 
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Power Pod & Spoilers

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Based on the reported AUW and wing-loading of previously built MMs, I'm worried about losing mine in strong thermals. Have decided to add spoilers. For emergency power to return to home maneuvers, am building a power pod: 50 amp ESC, 1600 mAh 3S. Any suggestions for a HK motor?

@Arjan, for your inspiring video, what onboard camera did you use? 808 keychain camera?
 
wingsoverk2 zei:
@Arjan, for your inspiring video, what onboard camera did you use? 808 keychain camera?
Klik om te vergroten...
yep.

As for power; a 1600mAh is quite a lot. You cpuld use 1000mAh instead.
A 40 to 50 grams motor with a kv of around 1200 to 1400 should work since you can only use a small prop.
A motor in the nose would be the better option as this does not add weight (you need the weight in the nose to get the balance right anyway, yet a pylon motor sits on the CG and only adds weight without helping balance)
With a nose-mount motor aim for a kv of around 1000 spinning a larger prop.
 
Gotcha, you're right. Just hate to chop off my MM's ugly pretty nose. Actually, it's just cyanocrylate tacked in couple of spots as I'm still waiting for nose tow-line hook release from HK. I usually use separate battery packs for motor and receiver, servos, etc.
I could not find any brass strip for the landing skid so use a junked oil dipstick. It has the right temper for spring-iness
Himalayan MMXIII Schneider Trophy biplane - RC Groups
And my last confession: This baby will hopefully fly (after manual maiden) autonomously with APM2.5 clone from HK. I am installing GPS receiver in nose so ESC and motor will play havoc...
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But, YES, I do love big props... will do as advised but for maiden, and IF the weather holds I will maiden her with hi-start.
Thanks again for your advise.
Best
Vikram
 
CG, lift, penetration

DirkSchipper zei:
I don't think finding the right center of gravity is more difficult at higher altitudes.

Dirk
Klik om te vergroten...
Don't know how I missed that. In this context I was referring to finding the ideal weight: lightness for good polars, sink ratio, and heavier weight for penetration, endurance. CG is same for all altitudes.... I believe.
The heavy monsoons this season are causing lot of problems. Need to invest in industrial scale dehumidifier or climate controlled room. My biplane fuselage started to warp during curing process. Moved the MM upstairs to where I currently sleep.
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Single Malt & Blends in Bed?

loeki zei:
"off topic": do you drink in bed???;)
Klik om te vergroten...

Haha, no Loeki. Bedroom is driest place in house so also serves as storage of items that can be damaged by monsoon dampness mould/mold. Largest case you see (Piper's Clan) is our local brand. This year the monsoon is record rainfall. No flying days foreseen until October-November I think.

In other news, Mr. Ryan Grosswiler, the designer of the Medicine Man has graciously corresponded with me. I was not aware he has 100" and 2-meter versions of Medicine Man also. He's building another aircraft, in Afghanistan of all places. Hope he posts plans for that also.

Unfortunately, he and I share different philosophies when it comes to the purity of soaring. On his website Building a Real Kit: FAQ he states "Some sailplanes fly with a low-powered motor to help them launch and get out of trouble, but in my book that’s cheating!" That's similar statement to friends who say "Leave the winch on the ground" when they see a motor or engine on a sailplane. Oh well.
 
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Installing RDF900 telemetry (900MHz) system, one rubber duckie on aft fuselage. The other diversity antenna will be in port wing. Starboard wing has GPS receiver.
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Van de Himalaya naar de Posbank, klein stapje lijkt me. Spulletjes besteld, Arjan; aanstichter van dit topic, lastig gevallen voor updaten van locatie bouwbeschrijving, tekening geprint, zachtboard gehaald: het feest kan beginnen ;-) !
 
gistermiddag gestart met het achterdeel, vleugelhelften net klaar dus die kunnen mooi drogen, op naar het rompje! Tot zover lukt het bouwen heel aardig; vraagtekens lossen meestal vanzelf op tijdens de bouw en turen naar de foto's uit het bouwverslag.
 
bouw lag even stil maar het vlot heel aardig. Kan nu bijna aan de romp beginnen, twijfel of ik de MM op een of andere manier electrisch wil maken..
 
bouwverslag

Het is alweer een tijdje geleden dat ik dit bouwdraadje tegenkwam en de Medicine man heb gebouwd. Hij moest alleen nog bespannen worden. Maar hier dan het resultaat:


Groet, Erwin
 
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