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All Forums >> RC Airplanes >> Giant Scale Aircraft - 3D & Aerobatic >> Quique's Aircraft Support >> 73" Yak at 6000FT MSL - What engine?
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73" Yak at 6000FT MSL - What engine? - 8/10/2006 7:52:07 PM   
zope_pope



Posts: 1045
Joined: 1/19/2003
From: Aurora, CO, USA
Status: offline 		Hi there,

I was wondering what engine would you recommend for the 73" Yak at 6000FT MSL. The air is always thin in Colorado and in the 1.20 Glow size aircraft, I can't seem to find an engine that will allow me to pull out of a hover with a lot of authority. I have a 1.40DZ and still have some trouble. I am not sure the 1.60 is bigger. Should I just think about going for the 26% Yak with a DA50, or do any engines come to mind that may help me out. Thanks a lot. I look forward to getting my hands on one of these.

Adam

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RE: 73" Yak at 6000FT MSL - What engine? - 8/10/2006 8:00:44 PM   
arobatx


 

Posts: 1764
Joined: 1/18/2006
From: Kalona, IA, USA
Status: offline 		I think the YS 1.40 sport, L or DZ would work fine. The straight sport with Cool Power Heli 30% and a 17x8 inch prop should do the trick. I wouldn't compromise on the fuel, just go down in prop size to keep your rpm's right 8500-9000. You've got an excellent engine, and though I am in Iowa, all I have read about this issue is to go with really good fuel, and there isn't a better one than the Cool Power Heli 30%...then adjust your prop size to keep your engine running happily at the intended RPM. I know some of you have a real battle with that altitude.

Good luck!

< Message edited by arobatx -- 8/10/2006 8:09:27 PM >

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RE: 73" Yak at 6000FT MSL - What engine? - 8/10/2006 9:09:47 PM   
Rezagh


 

Posts: 1827
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline 		Hi Adam,

Unfortunately, at that altitude you will see power reduction quite a bit. I still think YS 1.4 is a good choice but won't be ballistic. YS 1.6 has more vibration but will give you more juice. Make sure if you used YS 1.60, you use the soft mount.

Thank you for your question,
Reza Gh.
Quique's Aircraft Support

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 12:12:55 AM   
zope_pope



Posts: 1045
Joined: 1/19/2003
From: Aurora, CO, USA
Status: offline 		Thanks for the responses. With the 140DZ what does the 73" Yak come out to in terms of weight? I have it in a 13 lbs DPM bipe right now and it pulls it okay, but not really enough for me to learn 3d since I cant pull out with authority.

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 2:16:23 PM   
arobatx


 

Posts: 1764
Joined: 1/18/2006
From: Kalona, IA, USA
Status: offline 		Zope Pope,

I have the 73" QQ Yak with the 1.40 in it. Jr 8231 servos on ail and ele, 8411 on rudder, 1400mah 5 cell battery, 17-1/2 tetra tank, Hyde Type C soft mount, Tru-Turn spinner with lightened backplate and have narrowed down to two props, APC 17x8 and 18x6. On a digital fish scale it came out at exactly 11 lbs and it hovers at 1/3 throttle, running Sig 25% two stroke on the 17x8. When I started running the Cool Power Heli 30% I can run a 18x6 at 300 more rpm offering a few more pounds of thrust. It is really incredible. I would think even at your altitude, your DZ is a bit stronger than my sport, and on the same fuel/prop combo you should be doing pretty well. I can post some pictures of how I incorporated the hyde type C mount if you are interested in going that way. The mount is predrilled and tapped for the 1.20-1.70 YS and sets the thrust washer out quite a bit further than the OEM setup with the YAK. So I came up with an easy way to sink the Hyde mount into and behind the firewall to get the same firewall to thrust washer distance called for. Good luck, let us know what you end up doing, and how it works for you!

Chad (Arobatx) Iowa City, IA

< Message edited by arobatx -- 8/11/2006 2:22:20 PM >

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 7:39:45 PM   
zope_pope



Posts: 1045
Joined: 1/19/2003
From: Aurora, CO, USA
Status: offline 		Hi Chad,

Thanks for the note. 11 lbs is really incredible! Finally a company that quotes accurate weights. At my altitude, I spin the 18x6w APC at about 9400 rpm's. I was thinking of trying to go with the Bolly 19x6 to try and get the extra thrust. I run 30% Cool Power as well. The Dz can even turn a 20x6 at 7800 rpm, but it ends up being less thrust according to my fish scale rig. I think max thrust I have come up with is about 17, but I haven't measured with the 18x6w. I just know the DPM Ultimate that it flies right now has unlimited vertical, but not quite enough for 3d. Ofcourse the plane weighs in at 13 lbs without the 24 oz tank I fly with. :P Anyone have experience with the Bolly? I think this combo may just be enough for an 11lbs airplane. I am still leaning towards a DA 50 in the 85" jsut because I know for sure it will be enough. Anyhow, thanks for all your input so far guys.

< Message edited by zope_pope -- 9/5/2006 5:56:02 AM >

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 7:47:55 PM   
arobatx


 

Posts: 1764
Joined: 1/18/2006
From: Kalona, IA, USA
Status: offline 		I certainly won't steer you away from the QQ 85" and DA50, man what a combo. Honestly, with how well designed the 73" is, I feel like I just have to get a bigger one, I can only imagine taking all the good in the little one, and kicking it up a notch as you go up in size. Good luck!

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 7:53:50 PM   
zope_pope



Posts: 1045
Joined: 1/19/2003
From: Aurora, CO, USA
Status: offline 		Haha, yeah. The 73" would be a lot cheaper though. Ever since I heard that QQ had little if any mixing on his airplanes, I just had to get one. We'll see how it goes. I have far too many bipes in the hangar anyway, and I have already had an extra and an edge, so i thought I would try a Yak. Maybe I'll just have to get both the 73 and the 85.

What does the 85 with a Da50r come out to in terms of weight?

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 8:21:37 PM   
shakes268



Posts: 1281
Joined: 1/11/2005
From: Brentwood, TN, USA
Status: offline 		It depends. If you build them light around 15.5 pounds to 16 pounds I believe. I think the lightest ones were around 15.5 lbls. Keep in mind, the 85 is being replaced by the 86" that will be as light as or lighter (from what Reza stated) and be easier to assemble.

Its true though about no mixing. My 85" and 102" have no mixes all. There's pretty much no coupling and what little there may be is so small you compensate for it without thinking about it. Just roll to knife edge it and locks in My jaw dropped the first time I did it.

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RE: 73" Yak at 6000FT MSL - What engine? - 8/11/2006 9:06:28 PM   
Rezagh


 

Posts: 1827
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline 		The new 86 will probably be a little lighter. New design in construction of the fuse. I'll keep you all posted.

Thank you,
Reza

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RE: 73" Yak at 6000FT MSL - What engine? - 8/12/2006 12:33:00 AM   
zope_pope



Posts: 1045
Joined: 1/19/2003
From: Aurora, CO, USA
Status: offline 		Hmm. Thats interesting. I may just have to wait then. I didn't know about the 86" coming out. Any chance it will be out by xmas?

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RE: 73" Yak at 6000FT MSL - What engine? - 8/12/2006 12:36:01 AM   
shakes268



Posts: 1281
Joined: 1/11/2005
From: Brentwood, TN, USA
Status: offline 		Here's the info thread. Not sure if dates have changed but no one says they haven't.

http://www.rcuniverse.com/forum/m_4360496/tm.htm

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