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Author Topic: 4 stroke bislob?  (Read 2322 times)

Offline bob branch

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4 stroke bislob?
« on: August 10, 2010, 11:54:13 AM »
Has anyone tried to fly a bislob with a 4 stroke? I am doubtful about it because it seems like the guys who really do them well with 2 strokes set them pretty rick and they transition to 2 stroke mode to lock into  the hover. Seems like the 4 strokes constant run would negate that ability. Anyone have any experience?

bob branch

Offline Robert Zambelli

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Re: 4 stroke bislob?
« Reply #1 on: August 10, 2010, 01:25:26 PM »
I nominate Bob Branch to try a 4-stroke slob.

Anyone second?

Seriously, Bob - I have never seen it done but a test is worth one thousand expert opinons. If you have the means, give it a try. Might be a whole new experience.

Bob Z.

Offline bob branch

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Re: 4 stroke bislob?
« Reply #2 on: August 10, 2010, 01:57:41 PM »
Bob

The reason I asked is because of the other power system not already mentioned. I have been pretty much all electric for a couple of years now under Rick Sawicki's toutalage. The Adamisin clan has also worked with Rick and myself and we have had discussions among us about the idea. I think Dennis has one under way. My concern is the same with electric. With our governor systems the motor just keeps pouring on power to hold constant rpm, more like a 4 stroke runs. Though we do get a big increase in power in doing that, much like a tuned pipe but much faster and essentially the power increase to hold rpm is only limited by the power available in the system. Since we are able to download the data with some of the systems we can see the percentage of power we are using, optomize our power draw to the power available which will be different with each battery, motor, prop configuration, even with different line lengths. I've got a NIB saito 40 that has been wanting a home and thought I would see if anyone has done it. I fly a lot of 3D in RC and the way the old fox .35's 2-4-2 is just ideal for it.  I think the answer to it in electric will eventually come from the fully active power control systems like those the europeans used at the worlds this summer are developing. Still the electric and 4 stroke systems have a lot in common so I'm bassically surfing for info.


But of course there is still that Saito in the box.

bob branch

Offline David Shad

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Re: 4 stroke bislob?
« Reply #3 on: August 10, 2010, 07:28:59 PM »
Why not the four stroke with a three line system and then you can use the throttle control to play with all that power and torque...
Big Dave AMA 80235

Offline bob branch

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Re: 4 stroke bislob?
« Reply #4 on: August 10, 2010, 10:00:30 PM »
I think after a bunch of loops you will have an uncontrolable mess with a 3 line system won't you? I have never flown one so I don't know how much they will handle and still function. But in this kind of flying you are not doing a pattern that unwinds itself. Thing can get pretty twisted and happen very very fast.

please don't take this as an all knowing bit of knowledge. I don't know, I am basically asking.

bob branch

Offline Martin Quartim

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Re: 4 stroke bislob?
« Reply #5 on: August 10, 2010, 11:48:06 PM »

not sure if it is possible, but a 4S could be setup to speed up when the nose goes up if you find a way to put the tank back enough and use a larger venturi so any tank movement will make the engine pick up rpms. We have managed to do this with a Saito 72 and we could hear the engine picking up a few rpms.

perhaps  a special venturi with the Spray bar placed  higher in the venturi, sort of in the middle of the venturi taper, may weaken fuel draw, if you run rich in level it might pick up quite a few RPMS when the nose goes up.

Or better yet, a venturi with no taper, a straight hole as wide as possible and then put Bob infamous Nylon screw under the Spray bar  and another screw on top. you may have a chance to control total air restriction separately from  negative pressure acting on the Spray Bar Fuel Nozzle. controlling fuel draw capacity you may have some control of how much the engine changes RPMS with attitude.

Martin
Old Enya's never die, they just run stronger!

https://www.youtube.com/user/martinSOLO


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