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01-10-2014, 09:39 PM | #1 (permalink) |
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Mikado Logo 800 and Wren 44k
Some thinking out aloud about the potential of converting my Logo 800 to turbine. Please feel free to point out the "errors of my ways" in my thought so far.
1) I understand the use of the clutch bell in the Align 700 conversion, as this started off as nitro, but given the nature of two stage turbines, I see this as unnecessary in an electric to turbine conversion. 2) given the above is sound, would it be possible to have a shaft extension machined to thread on to the output shaft so that is reduced to 8mm diameter of the original electric motor shaft and thus use original pinions? The factory pinion is supported by a bearing at either end. 3) Given my Pyro 800-40L electric motor is theoretically at 23520 rpm on fully charged 14S lipos, is the quoted rev range of the 44K output shaft at 4000-15000rpm wide enough to accommodate a direct drive to my current pinion on a 175main/19pinion setup. I'm figuring chasing 1600-1800HS which is a little slower than I fly now. 4) Can the Wren FADEC accept its throttle input from a Vbar governor? 5) My current batteries weigh 2000g and my motor/ESC approx 800g so I'm thinking the turbine/anciliary weight plus 1.5l of A-1 is close enough to being equal. 6) Mounting turbine with FOD screen forward may allow fit under factory canopy with exhaust clearance too. Would also help with COG. Anyway, probably enough questions for the moment. No rush on replies as this is a "maybe" project. I do however intend going turbine at some stage in the future.
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Regards, Jayson Logo 800Xx Silverline, Pyro 850-40L, Kosmik 200, 14S, 157 & 256 @ 8v Logo 400SE Silverline, Pyro 600-09, Jive 80+HV, 8S, 9660A+ 8900G @ 6v Last edited by Jays200; 01-13-2014 at 03:58 PM.. |
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01-11-2014, 03:02 AM | #2 (permalink) |
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Great idea, Logo with a turbine. I think it would be possible with the right frame adjustments, what they also use for the trex 700 but then specially made for a Logo. I know guys who adjusted a Kasama or a TDR for turbine. So why not try with a logo.
I just think it is not an easy project
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01-11-2014, 08:13 AM | #3 (permalink) |
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I can say that number 4 is a possibility. I ran a Bergen 44 Magnum with the Wren 44 on a vbar governor. Here is a thread documenting it, https://www.helifreak.com/showthread.php?t=280698. It's not perfect, but it does work.
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01-11-2014, 01:35 PM | #4 (permalink) |
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I toyed with the idea of a turbine 800 last year, but shelved the idea. Main problems were gearing, ideally you would need a around a 22t pinion otherwise you are going to be running at the top end of the recomended gearbox range on a 19t to get 1650 rpm.
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Trex 600N Pro with Vibe 50 Head and YS91RS motor, Vibe 50 VBar FBL, Trex744 VBar FBL MW44 Turbine, Logo 800 XXTreme, Logo 600 12s, Logo 500SE, Vario UH-1D (Building), Scratch built 625mm Quad. |
01-11-2014, 05:58 PM | #5 (permalink) |
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Guys, thanks for the replies.
Kevin, that gearing is my main concern too and as Mikado only go to a 19T pinio,n I had given some thought to extending the pinion shaft down in to the battery bay area. This way, it could accept another gear and then running one of those short, wide belts (like found on the Banshee) from another drive gear on the output shaft of the turbine to give the required gearing up. Obviously, not as discrete as a direct drive. Mikado, like Kontronik, being German (no offense to our German brothers, it's just how they do business), aren't that good at responding to customer requests so asking for a larger pinion around the 22T mark would be a long shot. The Logo 800 gear train is more than capable in its current form since I've had 195A peaks and read of others in the 240A area at 14S (58.8V). That's 11-14kW peaks
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Regards, Jayson Logo 800Xx Silverline, Pyro 850-40L, Kosmik 200, 14S, 157 & 256 @ 8v Logo 400SE Silverline, Pyro 600-09, Jive 80+HV, 8S, 9660A+ 8900G @ 6v |
01-11-2014, 06:46 PM | #6 (permalink) |
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Any outfit that manufactures gears should be able to do you a gear of the right size. It does not have to come from Mikado.
Herringbone gears are a bit of a pain to do, but should be possible. The alternative is to get a slant main gear made, then you have a ready source of pinions.
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01-13-2014, 09:32 AM | #7 (permalink) | |
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Quote:
There's a Whiplash conversion from Hubschrauber.de that uses a custom 14T pinion with the 124T stock main gear for a similar ratio of 8.9. In the Youtube video they clearly fly it at 1800+ RPM with a gear box RPM of about 16,000! The interesting thing is that they specifically chose this gear ratio with a custom 14T pinion (smallest MinAir stock is 15T). I'm scratching my head on this one but, unfortunately, the designer of the Whiplash conversion (Inkos) passed away recently. For comparison, the Bergen Magnum ratio is miles away at 900/14=6.4 yielding an output RPM of 11,500 from the turbine; a seemingly more sensible operating point.
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01-14-2014, 08:42 AM | #8 (permalink) |
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And we can build the 44 Magnum in an 800 size as well...
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Chris D. Bergen Bergen R/C Helicopters |
01-14-2014, 05:11 PM | #9 (permalink) |
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G'day Chris,
Thanks for commenting. I have a few of questions for you. I have had exposure to a couple of your helis way over here in Western Australia and of course a turnkey solution is appealing. I have also studied your website. Please don't take my comments below as any form of criticism - perhaps just free potential customer feedback. I have the utmost respect for small business people and I understand the way you operate your business from reading many of your posts over many years lurking in the turbine shadows. All the photos on your website show flybarred helis. It would be nice to see some larger photos of more modern FBL helis since you offer the FBL option. How many FB vs FBL helis do you sell? Just a ratio would be interesting. Perhaps you could put some dates on your website as to when a page or photo was updated. Some photos of the new Kero start machines with a cleaner install would be good. I really like direct to swash control and am no fan of the push/pull multi link/bell crank arrangement. I'm a "keep it simple" kind of guy and that is why I am not interested in the Trex700 conversion. Mikado do a very good job of this and have a very robust drive train. All of my different size helis have their strength and weaknesses but I particularly like the idea of a 800 size turbine Logo. Your helis still use a clutch on a two stage turbine. No one has yet explained to me why this is necessary. My logic is it isn't since the turbine has a built in "air" clutch and again, in the vein of keeping it simple, less parts is more. You still offer the Wren MW54 two stage but Wren don't seem to list that on their new website. Given the performance increases over the years on the MW44, has Wren decided to drop the MW54 from their line-up?
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Regards, Jayson Logo 800Xx Silverline, Pyro 850-40L, Kosmik 200, 14S, 157 & 256 @ 8v Logo 400SE Silverline, Pyro 600-09, Jive 80+HV, 8S, 9660A+ 8900G @ 6v |
01-15-2014, 11:34 AM | #10 (permalink) |
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Jayson,
I can answer some of your questions, some I can't. FB vs FBL? About 50/50, but understand that we aren't simply a Hobby Helicopter Manufacturer. A lot of our sales are "Industrial", and most of those prefer a flybar. Personal preference.... Does a picture of a heli REALLY look that much different with a FBL Head on it? I see the FBL as an option, just like the different colors that we offer. We do have pics of the FBL head on the site, but I think the heli looks pretty much the same in the air... The AMA has (had) a rule in the books requiring a "disconnection" between the turbine and the rotor system. Yes, there is no direct connection between the gas generator and the second stage in a 2 stage turbine, but it is NOT recommended that you hold the second stage still while the turbine is running. Many would offer the idea that there's no reason to hold the rotor system still while the turbine is running, and in normal everyday flying after all adjustments have been made and all bugs worked out of the heli, I might agree. However.... I do like to take a close look at the heli and turbine while it's running, to inspect for leaks or any other issues that may only occur while the turbine is running, also I like to read the HDT for temp's, RPM's, and pump pressure. During initial test flights of a brand new heli, there may be adjustments like blade tracking, tail rotor setup adjustment, etc, that I like to do WITHOUT having to shut the turbine down to accomplish. These things would be impossible to do without a clutch installed in the drive train. Also consider that in the event of a crash, the clutch may help to disconnect the shock of the crash (rotor blades hitting the ground) from damaging the gears in this expensive component, but one could hope that the main gear would strip before that happened. The Wren 54 is no longer offered for sale, we do have the option of putting the Jetcat SPH5 into our Intrepid Turbine model. HTH,
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Chris D. Bergen Bergen R/C Helicopters |
01-15-2014, 05:51 PM | #11 (permalink) |
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Thanks again Chris,
Certainly explains your reasoning behind a clutch install. Could you please tell me the shaft diameter of the pinion mount. 8mm would be good for a Mikado pinion. This is a link to our national governing body, the Model Aeronautical Association of Australia (MAAA), and their Manual of Procedures (MOP) for gas turbines. http://d1070190-1981.myweb.westnetho...bine-Rules.pdf No mention of a disconnect (clutch) for us here in Oz. How does this rule apply to the two stage turboprop turbine in the US? I think I will send Wren an email to ask about the potential damage/risk to the power turbine (second stage) if it is held stationary in the exhaust gas stream.
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Regards, Jayson Logo 800Xx Silverline, Pyro 850-40L, Kosmik 200, 14S, 157 & 256 @ 8v Logo 400SE Silverline, Pyro 600-09, Jive 80+HV, 8S, 9660A+ 8900G @ 6v |
01-16-2014, 07:56 AM | #12 (permalink) |
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Hey Jayson, have you had a chat to Brian Simpson (Perthrc) about this exercise?
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01-16-2014, 10:13 AM | #13 (permalink) |
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Jayson,
How would you comply with the clause quoted below if the rotors were turning during startup? "It is also a requirement that the installation include a manual (by hand) means of shutting the turbine down and that th is method be accessible during the whole start up and shutdown phase of the turbine. " |
01-17-2014, 01:50 AM | #14 (permalink) | ||
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Quote:
Quote:
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Regards, Jayson Logo 800Xx Silverline, Pyro 850-40L, Kosmik 200, 14S, 157 & 256 @ 8v Logo 400SE Silverline, Pyro 600-09, Jive 80+HV, 8S, 9660A+ 8900G @ 6v |
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01-17-2014, 09:54 AM | #15 (permalink) |
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"Shaft diameter of the pinion mount"? I'm not sure what you're asking....
As I don't fly fixed wing, I'm unfamiliar with the rules regarding turboprop engines in airplanes. If it's used in a heli, then I would think the same rules apply....
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Chris D. Bergen Bergen R/C Helicopters |
01-17-2014, 10:45 AM | #16 (permalink) |
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A turbo prop airplane does not require a disconnect to the propeller.
On a heli if the rotor is turning there is no safe way to access any part of the heli to manually shut down the turbine in an emergency. On an airplane you still have full safe access to most of the airframe while the propeller is spinning.
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Jeff Borowski |
01-18-2014, 12:49 AM | #17 (permalink) |
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WOW!
Just received an awesome response from Mike Murphy at Wren. I've removed the original email from Mike as it answers questions specific to me and may not apply more broadly. Bottom line, clutch needed. Rpm range explained further and appears could work well on factory Mikado pinion. Chris, sorry for the vague description. I meant having an 8mm output shaft on the turbine to fit a 8mm pinion too, Mike explains Wren could manufacture the shaft to requirements but again a clutch bell negates this.
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Regards, Jayson Logo 800Xx Silverline, Pyro 850-40L, Kosmik 200, 14S, 157 & 256 @ 8v Logo 400SE Silverline, Pyro 600-09, Jive 80+HV, 8S, 9660A+ 8900G @ 6v Last edited by Jays200; 01-20-2014 at 08:00 PM.. |
08-10-2014, 05:06 PM | #18 (permalink) | |
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Quote:
Been pondering about this for a while and I see no other concerns than the pinion-issue. After reading 44K manual I came in my calculations to conclusion that the 22t pinion would be needed and this became kinda key-issue. Clutch and manufacturing supports to that is possible to overcome far more easily than custom-made (ridiculously expensive) 22-23t pinion so this really is a possibility. How is Your project going or is it on hold?
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10-25-2014, 05:06 PM | #19 (permalink) |
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Will be ready autumn -15 or spring -16 at latest. Quite a lot of small issues to take care of, most of theoretical issues are resolved. This should be fun (Picture is a draft of a sketch, don't take it too literally. And yes, no clutch.)
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