RE: Great Planes RV-4 .60-.90 ARF  
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RE: Great Planes RV-4 .60-.90 ARF - 11/22/2007 8:25:41 AM   
NorfolkSouthern


 

Posts: 903
Joined: 7/17/2006
From: Ann Arbor, MI, USA
Status: offline
quote:

ORIGINAL: bnflyn

Greetings,

This RV4 sounds like a really nice airplane. I was interested in the groups thoughts on using a 2 cycle OS 75AX for power in this plane. I searched the forums and did not see any mention of it. Thoughts?

Bernie


I've been thinking about this plane and engine combo too, and am wondering if anybody has really tried it, in spite of what some others suggested. Truth to be told, not everybody can afford a Saito 4-stroker, and I'm among the poor majority. I guess I'll just have to wait until I win the lottery before participating in a large scale event...

NorfolkSouthern

(in reply to bnflyn)
       Post #: 401

RE: Great Planes RV-4 .60-.90 ARF - 11/22/2007 8:02:36 PM   
Whistling Death


 

Posts: 1069
Joined: 3/1/2006
From: Alexander City, AL, USA
Status: offline
quote:

ORIGINAL: NorfolkSouthern

I've been thinking about this plane and engine combo too, and am wondering if anybody has really tried it, in spite of what some others suggested. Truth to be told, not everybody can afford a Saito 4-stroker, and I'm among the poor majority. I guess I'll just have to wait until I win the lottery before participating in a large scale event...

NorfolkSouthern

Thats good since it was designed with the O.S. FS-91 II Surpass in mind.

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(in reply to NorfolkSouthern)
       Post #: 402

RE: Great Planes RV-4 .60-.90 ARF - 11/23/2007 11:39:59 AM   
skorman


 

Posts: 519
Joined: 1/12/2003
From: Virginia Beach, VA, USA
Status: online 		I've had my RV-4 for about 6 months and I've enjoyed it very much. I am disappointed with the OS 91 Surpass II as its power plant. On this plane, it is just not enough power for me. I am thinking of putting in a 1.20 to 1.50 4 stroke engine in its place. Has anyone put a larger than recommended engine in this plane? Other than cutting up the cowl, are there any considerations I should be taking into account? Thanks in advance for anyones input.

_____________________________

Steve

(in reply to Whistling Death)
       Post #: 403

RE: Great Planes RV-4 .60-.90 ARF - 11/23/2007 6:33:11 PM   
Whistling Death


 

Posts: 1069
Joined: 3/1/2006
From: Alexander City, AL, USA
Status: offline 		This is a scale plane and a scale power plant so I isn't a fast plane. Personally I love it. Alot of guys are putting an OS 91 2 stroke to get more speed. Yes people are putting everything from 91 size to Zenoah G-38s. The bigger engine you put on the more stress you put on the airframe. So beefing up the fire wall, landing gear etc. etc. is a must.
I think a 120 would actually be a good large engine in this wonderful plane.
The guys at my club love this plane and they won't let me put anything else in this plane.

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       Post #: 404

RE: Great Planes RV-4 .60-.90 ARF - 11/23/2007 8:52:52 PM   
kaosfan


 

Posts: 23
Joined: 12/11/2006
From: Elk Grove, CA, USA
Status: offline
quote:

ORIGINAL: skorman

I've had my RV-4 for about 6 months and I've enjoyed it very much. I am disappointed with the OS 91 Surpass II as its power plant. On this plane, it is just not enough power for me. I am thinking of putting in a 1.20 to 1.50 4 stroke engine in its place. Has anyone put a larger than recommended engine in this plane? Other than cutting up the cowl, are there any considerations I should be taking into account? Thanks in advance for anyones input.


Fuel tank size may be an issue, at least when the engine is new. I can't believe how much fuel my first four stroker (just recently even-after 27 years of modeling) went through when it was new. My buddy had the same problem with a new Saito 1.80 in a Great Planes Giant Big Stik. He had to put a larger tank into it. Until we felt comfortable with leaning them the flight times were about 5 minutes. Maybe I am a wuss, but I would rather run a new one kind of rich at first.

I also am going to add some triangle stock around the firewall box area too.

I have not finished mine yet. I am going with the .91 Surpass. What kind of flight times are you getting from the stock tank?

As far as the .75AX, I think it would work. Heck, Great Planes says this model will fly on the .61FX. I initially started to put mine in this model just to see if it would work. But then I decided I wanted the 4 stroke sound. Then again, I have a YS 1.20 also. Whooee!

(in reply to skorman)
       Post #: 405

RE: Great Planes RV-4 .60-.90 ARF - 11/23/2007 10:32:57 PM   
skorman


 

Posts: 519
Joined: 1/12/2003
From: Virginia Beach, VA, USA
Status: online
quote:

ORIGINAL: kaosfan

I have not finished mine yet. I am going with the .91 Surpass. What kind of flight times are you getting from the stock tank?



I'm easily getting around 15 minutes of flight time with the stock tank and the OS 91 Surpass.

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Steve

(in reply to kaosfan)
       Post #: 406

RE: Great Planes RV-4 .60-.90 ARF - 11/23/2007 11:18:36 PM   
Arceenut


 

Posts: 98
Joined: 11/14/2005
From: Aldergrove, BC, CANADA
Status: offline 		Timer set for 15 min. Still had almost 1/3 tank after landing. Running an OS 91 4S on a 14X6 prop. Engine still set on the rich side as it is a new engine. Mind you I don't fly "balls to the wall" all the time .

(in reply to skorman)
       Post #: 407

RE: Great Planes RV-4 .60-.90 ARF - 11/30/2007 2:26:56 AM   
Ken Cz


 

Posts: 75
Joined: 11/1/2006
From: Oxford, MI, USA
Status: offline 		Hi Guys,
I am new to this thread so bear with me.

Picking up my RV-4 1/4 scale tommorrow plus a OS 91 4 stroker.

Question: What size prop do you recommend for break-in and then general sport/scale flying?
Also, should I consider an APC composite or maybe wood,???

Thanks for the help as this is my first larger plane and 4 stoke engine. Just want to be sure to do the right thing.

Ken

(in reply to Arceenut)
       Post #: 408

RE: Great Planes RV-4 .60-.90 ARF - 11/30/2007 4:28:51 AM   
fly24-7


 

Posts: 19
Joined: 12/18/2005
From: North Aurora, IL, USA
Status: offline 		The manual for the engine will have break-in procedures, including recommended props. I personally find that the APC props offer a little better performance than the wood (Top Flite, Zinger, etc...). However, some perfer the wood since they look more scale. Also, an APC can handle a minor prop strike. In most all cases, a wood prop sustains a pretty good crack on a prop strike and would need to be replaced.

(in reply to Ken Cz)
       Post #: 409

RE: Great Planes RV-4 .60-.90 ARF - 11/30/2007 11:22:07 AM   
Howard


 

Posts: 218
Joined: 9/12/2002
From: Viera, FL, USA
Status: online 		I have a new OS 91 four stroke (now broken in) in my RV-4 and after break in I tried an APC 14-6 and 14-7 and found the 14-7 to be much better suited. You will find that the RV-4 will get off the ground quickly but, it does not achieve an exceptionally high top end - quite realistic and fun to fly.

Howard

(in reply to fly24-7)
       Post #: 410

RE: Great Planes RV-4 .60-.90 ARF - 12/11/2007 8:21:28 PM   
Ken Cz


 

Posts: 75
Joined: 11/1/2006
From: Oxford, MI, USA
Status: offline 		Hi Guys,
Just assembling my RV-4 1/4 scale version wings and the directions say to just use wood/tapping screws for the aileron/flap horns and screw them into the wood blocks in the control surface. Hardly seems strong enough. (illustration in manual shows bolt-thru iusing plastic plate on top- whoops!)

I would think you'd want to thru-bolt and use the flat plate on the top side but that won't work because the aileron/flaps surface (top to bottom) are not parallel. IF you drill the holes square to the horn mounting surface they come out at an angle on the opposite surface.

Any solutions (make wedges out of lite--ply) you guys have found or do the wood/tapping screws hold up to the loads?

Also, the holes in the horn do not line up with the hinge line - that would affect travel. Any solutions like different brand horns or using the singe bolt type control horns? They have a long plastic' flag' that the clevis will hook up to and it may come out closer to the hinge line??

Thanks for the help. This is my first Big-Bird and I want to make sure I build it correctly.

Ken Cz - Oxford MI

< Message edited by Ken Cz -- 12/11/2007 8:39:47 PM >

(in reply to elvir)
       Post #: 411

RE: Great Planes RV-4 .60-.90 ARF - 12/11/2007 8:44:50 PM   
skorman


 

Posts: 519
Joined: 1/12/2003
From: Virginia Beach, VA, USA
Status: online 		I have around 50 flights on my RV-4 assembled as per instructions with wood screws. Leaves the scale look intact and seems to be very strong.

_____________________________

Steve

(in reply to Ken Cz)
       Post #: 412

RE: Great Planes RV-4 .60-.90 ARF - 12/11/2007 10:40:26 PM   
Whistling Death


 

Posts: 1069
Joined: 3/1/2006
From: Alexander City, AL, USA
Status: offline 		I have 30+ flights with factory gear and put together by the manual witout a hitch. You wouldn't need anything stronger unless you are going to over power it. As it is, if you build it per the manual you will be ok. I was a bit unsure about the screws at first, but Great Planes did a wonderful job engineering this one.

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       Post #: 413

RE: Great Planes RV-4 .60-.90 ARF - 12/11/2007 11:51:49 PM   
Ken Cz


 

Posts: 75
Joined: 11/1/2006
From: Oxford, MI, USA
Status: offline 		What do you do about the control horn holes not being aligned with the hinge joint? OK as is - set back off the hinge line?

Thanks for the feedback on the screws. I stick with them since the WORK!

Ken

(in reply to Whistling Death)
       Post #: 414

RE: Great Planes RV-4 .60-.90 ARF - 12/12/2007 12:01:42 AM   
Arceenut


 

Posts: 98
Joined: 11/14/2005
From: Aldergrove, BC, CANADA
Status: offline 		I built mine per the instruction with the screws into the block. I now have 20 plus flights on the bird with NO problems. Don't forget to harden the screw holes with Zap. The offset of the control horn is minor and the effect if any would be to give more downward deflection than up (differential ?). The effect is so minor that it is unnoticable.

(in reply to Ken Cz)