stunthanger.com
Engine basics => Engine set up tips => Topic started by: Avaiojet on December 10, 2011, 03:11:19 PM
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I have this NIB MVVS .49 CL engine.
I've seen on line, U-Tube actually, tamed, it'll turn between 7K and 8k.
I have this project, the Stiletto, revisited.
It's turning into a nightmare, well not really, but a bad dream at least.
Anyway, I'm rethinking this engine for the project. 540 sq's is a bunch for a .49 engine. Or is it?
Other recommendations would be considered.
Thanks in advance.
CB
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That engine will pull a 72 ounce 680 sq inch airplane with ease, through the pattern no less - I know, I ran mine on an overweight ARF Score. Not enough for a 530" sq? LL~
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That engine will pull a 72 ounce 680 sq inch airplane with ease, through the pattern no less - I know, I ran mine on an overweight ARF Score. Not enough for a 530" sq? LL~
Pete,
Thanks for the reply. I'm looking at it as it's not much more than a .40.
I also have a MVVS .40 but it's got a carb. I was going to use it for R/C.
Could you please tell me how you had yours set up? Pipe? Three blade prop? What RPM did you settle for?
Thanks,
Charles
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Header muffler, RSM 12x6 2 blade prop. Not ideal but I only use that plane as a test bed. If I were going to put it into a proper stunter I'd use a tuned pipe, 12" bolly 3 blade to start with. It is a torque motor, not high revver. Randy has pipes and headers that will work, probably header mufflers as well. FAI or low nitro fuel.The stock muffler is difficult to mount due to its straight header design. Plane would be at least 630" squares. It needs that size of airframe minimum to accommodate its 13 plus ounce weight. 8)
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Hi Charles,
Ditto what Pete said, My .49 pulled a porky 64oz shark like a .40 in a ringmaster lol.
Personally I'd put this engine in a serious stunt ship and find something more compact for your stiletto project.
At around 530 squares 1 would have to assume that a .40-.46 should handle it easily. (And be easier to accomodate)
Cheers, Rob..
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Hi Charles,Ditto what Pete said, My .49 pulled a porky 64oz shark like a .40 in a ringmaster lol.Personally I'd put this engine in a serious stunt ship and find something more compact for your stiletto project. At around 530 squares 1 would have to assume that a .40-.46 should handle it easily. (And be easier to accomodate)Cheers, Rob..
Rob,
Thanks for the reply.
If you take a look at the drawing of the Original Stiletto, you can see that the span is quite small for the size/length of the fuselage. The model wasn't designed to do stunts.
My enlarged model has to keep most of the original design in tact, otherwise there's no purpose in building the thing based on the original designer's efforts.
At 57" the wing is really different in proportion to the model's original wing. I'll probably settle in at around 570 to 590 sq's. I'll see what the span and cord is at that number, and Post it. The fuse is drawn at 43.5" in length an swallows the engine in it's belly.
At the moment, I'm fine tuning my drawings for the drive line.
CB
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Wasn't this originally a C/L Speed ship? Are you going to mount the engine aft w/ a prop shaft?
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Wasn't this originally a C/L Speed ship? Are you going to mount the engine aft w/ a prop shaft?
Douglas,
Yes, that's correct. Do you remember the model?
Someone posted a link, to the 1970 article, in a Thread. I apologize for not remembering who was kind enough to take the time to do this?
Yes again. I'm mounting the engine aft with a prop shaft. I know, I have a bit of work ahead of me.
However, and I'll quote a line from a movie, "I'm not a trout." ;D
There is an abundance of Threads on this subject matter, actually the model I'm building. I've been running my ideas in Threads. Gotten plenty of input and feedback. Input that has helped me make decisions. Thank you all!
Thanks for the response.
CB
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I'm looking at it as it's not much more than a .40.
Um, I think that the 49 really IS much more than the 40 due to the heavy commonality of parts in the 40/45/49 range.
Not only is it 0.09ci or 1cc bigger in capacity and therefore has more power, it has a far better power to weight ratio for stunt, and has the option of an Akrobat stunt timed liner which the 40 doesn't have. So the power in the low and mid range will be vastly superior to the 40.
If you are into sheer high end power then perhaps the Pylon version of the 40 will suit a speed pursuit better but for me, the 49 and the 51 are the pinnacle of the MVVS range for stunt.
By the way, the rear exhaust 'pipe' should not add to the power of this engine as its state of tune kicks in at 13 000 rpm and it simply goes along for the ride as a very lightweight canister that happens to follow a time worn design pattern of all MVVS pipes.
Cheers.
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Header muffler, RSM 12x6 2 blade prop. Not ideal but I only use that plane as a test bed. If I were going to put it into a proper stunter I'd use a tuned pipe, 12" bolly 3 blade to start with. It is a torque motor, not high revver. Randy has pipes and headers that will work, probably header mufflers as well. FAI or low nitro fuel.The stock muffler is difficult to mount due to its straight header design. Plane would be at least 630" squares. It needs that size of airframe minimum to accommodate its 13 plus ounce weight. 8)
Pete,
I have this exact engine also and don't envisage a problem with getting a steel tank under that pipe.
Do you see the height off the bearers as an issue here?
I am sorely tempted to place a saw cut right through the header pipe and placing a silicon joiner there to prevent possible cracking down by the mounting flange.
If this course is adopted then you can angle the pipe away from the tank that bit more also!
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Without a rise it looks to me that the straight header would make it difficult to get the fuel pickup in line with the spray bar. Not a problem as Mac's has a header that will fit the engine (listed for a 40R, fuselage top). It is curved so will clear the tank and allow for some adjustment. Randy may sell them also. This type of header could be used for a tuned pipe or with an insert, a header muffler. I think this would be better than modifying the stock muffler. 8)
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By the way, the rear exhaust 'pipe' should not add to the power of this engine as its state of tune kicks in at 13 000 rpm and it simply goes along for the ride as a very lightweight canister that happens to follow a time worn design pattern of all MVVS pipes.
Chris and Pete,
I could eliminate the pipe. Just cut it off as suggested by Pete. Nothing hard about that. This would provide extra room. Clamps and a drain hose out the back.
CB
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That was Chris that suggested cutting off the pipe. I suggested an alternative. 8)
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That was Chris that suggested cutting off the pipe. I suggested an alternative. 8)
Chris,
I have no problem with removing the pipe.
What did you suggest?
CB
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See reply #10. I'm out.
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Chris,
I have no problem with removing the pipe.
What did you suggest?
CB
I suggested that IF your tank fouls the underside of the standard Akrobat pipe the you could simply saw cut the header through, place a silicon joiner there and get more of an angle away from the tank thereby giving you more clearance. All this is with the entire original pipe system used and simply angled.
Note to self, I must measure what the clearance is now but at a glance it seems sufficient and if not then a custom made flatter and smaller tank less than1" high is easy enough to make. And since these engines are VERY fuel efficient they do not need anywhere near the tank room that you would expect.
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If you have the "Akrobat" (stunt) version of the .49, it will pull a 650 sq. in. stunter with ease. Mine is powering a modified Kolesnikov KA-10 (heavy at 65oz). It currently swings a Thunder Tiger 12.5x5.5 prop using 5% Nitro, 20% oil. It runs a nice 4-2 break with around 8K launch rpm. The engine is set up RE with a home-made muffler.
http://www.youtube.com/user/pampa9m?feature=mhee#p/u/16/RdwM-eU5tuE
Fred
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If you have the "Akrobat" (stunt) version of the .49, it will pull a 650 sq. in. stunter with ease. Mine is powering a modified Kolesnikov KA-10 (heavy at 65oz). It currently swings a Thunder Tiger 12.5x5.5 prop using 5% Nitro, 20% oil. It runs a nice 4-2 break with around 8K launch rpm. The engine is set up RE with a home-made muffler.http://www.youtube.com/user/pampa9m?feature=mhee#p/u/16/RdwM-eU5tuEFred
Fred,
I have the engine in the photo.
CB
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Fred,
I have the engine in the photo.
CB
Hi Charles,
That engine should easily pull your re-designed Stiletto racer. A drive shaft is not a huge problem. Model hydros with racing .65s have drive shafts................. lots more power and rpm than any of us use for stunt.
Big Bear
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Fred,
Is this you flying that model?
http://www.youtube.com/user/pampa9m?feature=mhee#p/u/16/RdwM-eU5tuE
CB
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Without a rise it looks to me that the straight header would make it difficult to get the fuel pickup in line with the spray bar. Not a problem as Mac's has a header that will fit the engine (listed for a 40R, fuselage top). It is curved so will clear the tank and allow for some adjustment. Randy may sell them also. This type of header could be used for a tuned pipe or with an insert, a header muffler. I think this would be better than modifying the stock muffler. 8)
Pete,
Thanks for that, I didn't see it.
Yes, great idea, beats cutting a tuned pipe that I may want to use on another model.
Also, even with the bend giving room, I'm not sure how far back from the spray bar, I can place the tank.
As you know, I can rotate the cylinder 90 degrees, possibly have something custom made?
Thanks again!
CB
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CB,
Yes. That's me flying. Bill Smith is the other person in the video.
We are very fortunate to have this flying site until Honda Aviation decides to built their sales facility. Then we'll have to do some serious searching.
BTW, my RE muffler uses a riser header from MVVS. This provides plenty of room for tank adjustment. I'm sure Randy's header is very similar.
Fred
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CB,Yes. That's me flying. Bill Smith is the other person in the video.
We are very fortunate to have this flying site until Honda Aviation decides to built their sales facility. Then we'll have to do some serious searching.BTW, my RE muffler uses a riser header from MVVS. This provides plenty of room for tank adjustment. I'm sure Randy's header is very similar.Fred
Fred,
Got a photo of that "riser header?" I believe I could rotate it 180 degrees. Then it would go under the wing.
Nice photo. ;D
CB
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CB,
Here's a photo from an ACLN article on the MVVS .49 Akrobat. The engine, MVVS header pipe and muffler were sold by Just Engines a few years ago. If you need dimensions, I can post the rise distance. MVVS no longer makes the engine or accessories, however, as other folks stated, you could check with MACS or Randy Smith for a suitable header pipe.
Fred
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The standard exhaust will be fine, and there is no need to change from the original rear exhaust configuration either as it simply is the most logical setup for an invert engine mount.
As to MVVS not making the engine OR the accessories anymore - I agree with the former but not the later.
You will be pleasantly surprised on what exactly is still available if you contact the factory.
I recently purchased the piston/liner setup, the factory tuned pipe, two manifolds and had Josef Svadja there offering to make any exhaust that was not in stock.
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Chris,
My pipe goes right through the bloody wing. That'll leave a mark. ;D
So, Fred's offering could help me with that.
I think I should purchase one of those pipes.
Parts? There's a MVVS rep that hangs out at RCU. Don't know what Country he works out of?
CB
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Chris,
I've been doing some drawings for an R/C guy in Australia.
Chittaway Point. Ever hear of it?
CB
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Chris,
My pipe goes right through the bloody wing. That'll leave a mark. ;D
So, Fred's offering could help me with that.
I think I should purchase one of those pipes.
Parts? There's a MVVS rep that hangs out at RCU. Don't know what Country he works out of?
CB
Charles,
there are quite a few MVVS reps over at RCU, Dar Zeelon (Israel) , Pe´Reivers (Netherlands) and Jaka (Finland, I think) - just log on over there and contact them.
As to that standard spray bar not lining up with the tank, one of my 49's is set up for side mounting and so has an alloy venturi with the spray bar mounted through that and well above the standard position, so no problem with height there. In fact I see that having the bar out board as a good thing.
Another one has the crank case drilled (notice the little circle just underneath the standard bar on the intake stub) and has the spray bar going through there - this gives a slightly better position for tank alignment. This one is for an invert mount.
And the last one, the MVVS 51 with the rear intake, actually needs the bearers carved away to make tank room when invert mounting it.
So none of them are going to have the pipe interfering with the tank.
But I personally do not like the standard peripheral jet system for stunt use (meat for another topic) but who says that the spray bar MUST align itself with the fuel feed in all cases?
The engine likes it where it likes it and you will get quite a variation of where the tank needs to be between engine brands, their mounting orientation and model types.
If the exhaust still troubles you then Just Engines (last time I spoke to them) has the header riser system in stock but no canister mufflers, Brian Eather here in Oz has carbon tuned pipes (if that takes your fancy), the MVVS factory and their reps have the rear exhaust adaptor (part number 3260) or I am sure that our host here, Randy, can help out with a riser.
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CB,
Here's a photo of the MVVS header with a scale for reference.
Fred
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Some years ago I flew a couple of OD Vanity PA airplanes at 540 squares with Fox stunt 35 and had plenty power.
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Note to self, I must measure what the clearance is now but at a glance it seems sufficient and if not then a custom made flatter and smaller tank less than1" high is easy enough to make. And since these engines are VERY fuel efficient they do not need anywhere near the tank room that you would expect.
Ok, I have measured the clearance under the standard Akrobat pipe with my MVVS 49 that is modified with a straight through Enya spray-bar going through the bald circular dimple on the venturi stack.
A normal 1" high tank fits perfectly in the distance between the bearers and the pipe with about 1/32" to spare on the tanks front edge when jammed right up against the exhaust flange, and this is with the feed pipe centralised on the spray bar.
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Ok, I have measured the clearance under the standard Akrobat pipe with my MVVS 49 that is modified with a straight through Enya spray-bar going through the bald circular dimple on the venturi stack.
A normal 1" high tank fits perfectly in the distance between the bearers and the pipe with about 1/32" to spare on the tanks front edge when jammed right up against the exhaust flange, and this is with the feed pipe centralised on the spray bar.
Chris,
Thanks for offering that info. I may just rotate the inner sleeve to a side exhaust application and be done with it.
An option.
Thanks again,
CB
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Chris,
Thanks for offering that info. I may just rotate the inner sleeve to a side exhaust application and be done with it.
An option.
Thanks again,
CB
Charles,
two things to consider here -
1. make sure you rotate the upper barrel AND the inner sleeve as a pair (kinda obvious I know but you never know how things are interpreted here),
2. do not run the engine as a rear exhaust, change your mind then rotate it to a different orientation as you will abbreviate the engines life by having to run it in twice.
(In other words, choose your orientation up front and stick to it!)
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Probably off topic, but I run my MVVS 49 as a diesel (Davies Diesel conversion, not the original MVVS diesel setup). It is an absolute stump puller, so if you have any problems with lack of power, go diesel. The exhaust can be quite small in size and still works reasonably well.
Can anyone tell me what the Akrobat liner is timed at? I haven't a clue what my liner is?
Thanks,
Andrew.
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Charles,
two things to consider here -
1. make sure you rotate the upper barrel AND the inner sleeve as a pair (kinda obvious I know but you never know how things are interpreted here),
2. do not run the engine as a rear exhaust, change your mind then rotate it to a different orientation as you will abbreviate the engines life by having to run it in twice.
(In other words, choose your orientation up front and stick to it!)
Chris,
What upper barrel?!! What is that?
I haven't taken the thing apart yet, but I was just expecting to see a sleeve. Are you referring to the "head?"
Thanks for the heads up. Sorry I need more info. n~
CB
Hey! My extended shaft is being made along with the double bushing pillion. Found a guy that didn't want to change my design. Well, except for a couple of things. ;D
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Chris,
What upper barrel?!! What is that?
I haven't taken the thing apart yet, but I was just expecting to see a sleeve. Are you referring to the "head?"
Thanks for the heads up. Sorry I need more info. n~
CB
Hi again (Christmas break intruded, sorry for the delay),
upper barrel, same as 99% of two stroke motorcycles. They have a lower casting that houses the crankshaft and its attendant bearings and a completely separate casting that houses the liner and piston.
The liner and upper barrel must be rotated as a pair otherwise the ports will not line up and the engine, although hilarious to contemplate, will not run at all.
I did mention all of this previously and quite extensively in your drive line thread.
Mate, you sound like you need a build buddy much more than this forum - perhaps you could team up with some one, join a club or simply visit a hobby shop as its going to be far more informative and expressive.
Cheers.