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73" yak evolution 26gt

 
Old 08-07-2006, 01:46 PM
  #76  
rmenke
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Default RE: 73" yak evolution 26gt

Guys:

Have 4-6 flights on the Yak 54 and Elvolution 26 over the weekend. First flights were with a Xoar 18 X 6, IMAC type flying fine, not enough poop to hold it in hover. Second prop, APC 18 X 6 wide improved the rpm's and holding power to not loosing altitude. Engine has about 1.5 hrs on it and now on Mobile 1 2T. May be too soon for this oil, but ran out of Yammalube R. Someone reacommended cutting the crimped ends off the Bisson muffler, will give that a try, and maby go to the MVVS pitts muffler that is supposed to give her a little more power. Its close to ok as is, the Yak is so solid in all attitudes that you acquire overconfidence in my case. Had to throw things around at no speed to get a unrequested snap out of it. Very stable in all attitudes, love the thing. Landing, unlike some, is simple. Go to the low elevator rate recommended by QQ, turn final with near full up in it. It will take a nose up set, and fly in with throttle to adjust altitude. Sets down very nice, or show off a little and drag tail down the strip as far as you like, will just stay there like a good electric foamy. You will enjoy this combo even with the lack of power. Suspect the 3W 28I will be a outstanding combo. Dry weight turned out at 12.5# with spinner, flight battery back of canopy to CG. Set up with QQ's recommended CG, is perfect. ENJOY
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Old 08-19-2006, 02:43 PM
  #77  
clm
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Default RE: 73" yak evolution 26gt

I just finished my 73" with MVVS 26 with pipe. Weight came out at 11.6 lbs. Only three flights so no hover info. Do to using pipe the engine had to be mounted at an angle. Pictures showing air exhaust.

Pe,

Please comment on engine cooling from pictures.


All the Best
clm
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Old 08-19-2006, 05:27 PM
  #78  
Scooby_Dont
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Default RE: 73" yak evolution 26gt

Looking good although you may need to open up the cowl a bit for cooling.
I have 5 flights on mine with the mvvs 1.60 and a JMB muffler.
I'm really pleased with it so far, just need more flights.
Mine's is around 11.5 lbs as well.
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Old 08-19-2006, 05:28 PM
  #79  
pe reivers
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Default RE: 73" yak evolution 26gt

Almost done. This setup will only allow air into the cowl where it will assist in cooling the engine.
ToDo:
Open up all louvres, so the hot air is <sucked> out by the prop blast, which is very effective. This action is just as important as the blocking off of excess front opening.

As icing on the cake, and for 3D, make two simple side guide plates alongside the engine, so all air is forced through the fins. These can be very simple devices. I used 2" wide 1/32" thick aluminum plates bolted to the engine bearers and the cylinder head. This increases cooling by about 40%. If you use soft alu sheet, you can combine the exhaust header side with the header gasket, and do not bolt that side to the bearer.
The front of the cylinder gets scrubbed by turbulent air, and needs little attention. The plates should guide the air from the air inlet to the cylinder wide open, and past the centerline up to 3/4 the engine rear quite closely shrouding the fins.
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Old 08-19-2006, 05:42 PM
  #80  
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Default RE: 73" yak evolution 26gt

If you want to fly 3D with any gasser less than 2.15, get rid of the in cowl muffler and use canisters or tuned pipes. The 1.60 will provide excellent performance if you do keep the plane weight at 11 lbs max.
MTW makes very light stainless steel header pipes that save about 60 grams over the standard MVVS header.
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Old 08-19-2006, 08:10 PM
  #81  
clm
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Default RE: 73" yak evolution 26gt

Pe,

Your a wealth of knowledge. Thank you for the comments.
I got an aluminum header from MAC Pro. It is very light
All up dry weight = 11.6 lbs

Plane specs:
MVVS 26 engine
used radial engine mount (saved weight)
17-6 APC prop
Rudder = Hitec 5945
Ailerons = Hitec 5945
Elevators = Hitec 5925
Throttle = Hitec HS-81 (saved weight)
Custom MAC Pro Aluminum header (saved weight)
eCompusite Carbon Fiber pipe (saved weight)
I did not use metal wing pins, instead I used nylon 1/4-20 bolt in front and J-hook with rubber bands in rear (saved weight)
RCAT electronic kill switch
2 - 2400 Fromeco Li-ion batteries with regulators (saved weight)
Ign and ign battery are located in cowling
Kevlar pull-pull line with 2-56 eye-bolts
I split the main gear, if it ever breaks loose I want to minimize damage the CF pipe $$$
4" foam wheels - This added a little weight but our grass does not get cut as often as I would like
upgraded tail wheel to spring wire controlled type. Did not like supplied tailwheel. This added very little weight
No spinner or wheel pants (saved weight)
Fiber glassed main gear mount and firewall - added little weight


All the Best
clm


ORIGINAL: preivers

If you want to fly 3D with any gasser less than 2.15, get rid of the in cowl muffler and use canisters or tuned pipes. The 1.60 will provide excellent performance if you do keep the plane weight at 11 lbs max.
MTW makes very light stainless steel header pipes that save about 60 grams over the standard MVVS header.
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Old 08-20-2006, 01:41 AM
  #82  
pe reivers
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Default RE: 73" yak evolution 26gt

Performance with the pipe will be substantially better than with the Pitts Evo muffler as used in the QQ movie. As you can see in that movie, he also uses the baffled air entrance.
The APC is heavy, and too small. Use a lighter wood prop of 18x6. This should still spin the engine in excess of 9000 rpm and make plane response to throttle more lively due to better thrust figures.
I dislike the gear durability of the HS81. Use HS81MG instead, or you may strip gears sooner or later. Using a springy rod (like Sullivan Nyrod) or pull system also will prevent this.
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Old 11-20-2006, 02:51 PM
  #83  
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Default RE: 73" yak evolution 26gt

Reeza,
Has Quique tried any other props on the EVO and has he tried a tuned pipe. If not will he consider doing this and doing an update on his findings. This plane and motor could be perfect for me if I can get a bit more power. Unlike Quique, I need that power or the plane will not last long.
Thanks,
John
ORIGINAL: Rezagh

The video was made to help you guys make the right decision based on your expectations. It wasn't meant to sell you the engine! The shots were taken such you can see the pull out of the hovers and overall performance of the engine without hiding anything. As long as you can keep the RTF weight under 12 lbs and it's not a 40cc or up engine, you guys can put any engine you want. For higher altitude, I don't even recommend a gas engine. I think glow is the way to go.

Reza
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Old 11-23-2006, 09:17 AM
  #84  
scottiesoccer1
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Default RE: 73" yak evolution 26gt

Those of you using the Evo 26. We have over 60 flights now on ours and the power now just seems to be going through the roof so hang in there the motor will get more and more powerful. And hey whens the last time you flew 18 minutes with a 12 pound airplane, on 12 ounces off fuel!!!

Scott
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Old 11-23-2006, 11:14 AM
  #85  
Macommy
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Default RE: 73" yak evolution 26gt

What pipe are you using and what's the weight of your plane?
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Old 11-23-2006, 07:16 PM
  #86  
scottiesoccer1
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Default RE: 73" yak evolution 26gt

i am using the stock evolution exhaust and the weight came in at 11 3/4 pounds with a 5 cell nimh for the rx and a 4 cell nimh for the ignition. Its the airplane on our website the one QQ flew for the video. [link=http://www.qqaircraft.com]www.qqaircraft.com[/link] This is my personal plane. It flys great and you could shed some weight with some lipos instead of nimh.

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Old 11-24-2006, 01:03 PM
  #87  
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Default RE: 73" yak evolution 26gt

Hello friends,

My 72" Yak is as follows:

MVVS 26 with factory pipe
truturn spinner
APC 17-8
Smart-fly ignition cut-off with fiber optics
Futaba digitals all around
NiMh for ignition
Nicd 1800mAh for receiver
Virtual cockpit kit

The aircraft has around 10 flights on the clock and I am a believer! Both for the aircraft and for the combo. The all up weight is 5,2 kg and what I've seen so far is convincing. Its not a rocket, but with som "development work" I think this will be a great allrounder. This engine has a great power potensial. And what a beuty!

I must admit the engine has caused me som trouble, but this is maily because of my incompetence and bad luck. It has been twice to the factory for repair - and that tells something about good service! There is still something wrong with the ignition: After a while it drops to 2- 3000 rpm, but kicks back when I hit th.e ignition switch off/on. But a modeller never gives up!

Nevertheless, Pe has convinced me I need some baffles. Cooling has been a problem. I put some images on to show how far I come with the cowling. I even has installed a cowlflap in front of the pipe.

Show off!

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Old 12-07-2006, 01:04 PM
  #88  
JRS
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Default RE: 73" yak evolution 26gt

I have made nice baffles for my MVVS and borrowed a termometer to measure spot temp. Pe informed me that the cylinder head temperature should be at around 130C and not much above 140C. After some testrunning the CHT seemed to be on the high side. I have opened up all louvres and widened the front opening for more exponation of the engine top. Also opened up more behind the engine. Its been a long learning curve to get the cooling right on this engine - its my first petrol though. Its so hard to cut holes in these lovely covlings, buts its no way around..

I have bougt new props: 18-6, 18-8. Time will show the performance. Despite the global warming - its winter in Norway.

Take care
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Old 12-08-2006, 12:24 AM
  #89  
kochj
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Default RE: 73" yak evolution 26gt

I am selling my tuned pipe and stailess steal header combo and a radial mountand spinner adaptor for the evolution 26gt if anyone interested!
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Old 03-21-2007, 05:52 PM
  #90  
chadderbox
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Default RE: 73" yak evolution 26gt

Is there any video out there yet with the g26 combo with the tuned pipe?
I can't find any. Thanks any one?
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Old 03-15-2009, 03:49 AM
  #91  
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Default RE: 73" yak evolution 26gt

Hi, does anyone know if there is need to modify the firewall of the 73" - Evo 26, to fit the Evolution pitts style muffler (the black one showed on Quique´s video). If yes, does the modification meen to cut and move all the firewall? or is it a minor mod? Any photos available.

Thanks.
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Old 03-23-2009, 12:23 AM
  #92  
GeorgeAgs
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Default RE: 73" yak evolution 26gt

I have exactly the same question, I have the 72" QQ and I have removed the YS140 that had on it and now I got an EVO 35cc. I'm planning to add it with the radial mount, but the measure from the prop hub to the firewall is not 5.5" (14 cms) as QQ stated, it's 5.9" (15cms), I think this is not very important if I move the engine as required to keep the front of the engine in the center in order to keep the right thrust ok.

But if I want to use the EVO inverted muffler and I need remove one part of the engine box in order to get the muffler room.

So, the question is, I think I'm not the only one who is adding this kind of engines, does any of you have any picture, or if I do this modification will I risk the plane (obviously the mod will be with plywood and epoxy to get it right)

Thanks in advance.

Regards

Jorge Medina
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