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OS MAX .21 VZ-M Turbo for airplane use !

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Old 05-03-2006, 09:32 AM
  #1  
kristijan-k
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Default OS MAX .21 VZ-M Turbo for airplane use !

Hello,

Just got an idea and would like to ask here for some opinions.

Would it be possible to use OS .21 VZ-M Turbo engine on speed airplane ?

It seems that this is very powerfull engine.

I can make new air head, but would it work ok to cool engine with fuel and prop ??

Fuel from tank would go through engine marine head to carb (see picture below).


OS MAX 21 VZ-M TURBO

Displacement: 0.2 cu in (3.46 cc)
Bore: 0.65 in (16.6 mm)
Stroke: 0.63 in (16.0 mm)
Practical RPM range: 3000-40,000
Power Output: 2.5 hp @ 33,000 rpm
Weight: 12 oz (340 g)
Includes: P7 turbo plug

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Old 05-03-2006, 09:41 AM
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petec
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !

I may be way off base, but without a fuel pump to pressurize the fuel supply , it is most likely that the engine would suffer from vapor lock when the head got hot.

If you could get an air cooled head or find one of the old clamp on heat sinks that were popular with the heli guys in the early 80's it would be an interesting experiment.

My $.02
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Old 05-03-2006, 09:42 AM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !

KK, if you are able to machine a new head for it and adapt a prop to it, then you are capable of giving it a try in a speed plane. I have heard lots of talk about converting a .21 to aircraft use, just never have seen it done. I would be curious to know what rpm that engine could turn a 7x6 prop at ?
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Old 05-03-2006, 12:30 PM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !

ORIGINAL: combatpigg

KK, if you are able to machine a new head for it and adapt a prop to it, then you are capable of giving it a try in a speed plane. I have heard lots of talk about converting a .21 to aircraft use, just never have seen it done. I would be curious to know what rpm that engine could turn a 7x6 prop at ?
I get around 19K rpms from my K&B 3.5 with a 7x8 prop. Running 15% fuel. Lately I've started thinking I shoudl try some of my 50% boat fuel in it. And after this I may send it to one of the engine people I know and have them work their magic on it.
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Old 05-03-2006, 12:39 PM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !

ORIGINAL: kristijan-k

Hello,

Just got an idea and would like to ask here for some opinions.

Would it be possible to use OS .21 VZ-M Turbo engine on speed airplane ?

It seems that this is very powerfull engine.

I can make new air head, but would it work ok to cool engine with fuel and prop ??

Fuel from tank would go through engine marine head to carb (see picture below).
The plug cover is for cooling. When a boat runs it sends a significant amount of water through the cooling lines. Trying to provide the same level of cooling with fuel probably wouldn't work, you would not be drawing enough fuel to provide much cooling. Just make an aero head and allow the air to cool the plug.

In general, marine engines are heavier than plane engines. For example, Dubb Jett makes a .25 FIRE engine that weighs less, is ready to fly, and in the long run may be less hassle than trying to convert a boat engine.

If you really want to go the boat engine route, there are other options that have as much, or more power, from Nova Rossi, MAC, and CMB. For example, you can get a .21 from MAC for $259 right now. The OS seems like an exotic, high powered engine, and in comparison to the sport airplane engines that we normally see, it is. However, in the boat racing circles, it's just one of several choices in that power range.
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Old 05-03-2006, 01:09 PM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !

it would be easier to get the car engine and machine down the head for plane use.
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Old 05-03-2006, 04:52 PM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !


ORIGINAL: cncswiss1

it would be easier to get the car engine and machine down the head for plane use.
That's what I´m thinking to do with my car engine! I don´t play with car's anymore so...
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Old 05-03-2006, 08:28 PM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !


ORIGINAL: cncswiss1

it would be easier to get the car engine and machine down the head for plane use.
But then you have one of those weird cranks...

You could just leave off the plug cap and try it like that. If you truly get heat problems, which I doubt, you can get the car head clamp and machine it down to airplane size.
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Old 05-03-2006, 09:00 PM
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Default RE: OS MAX .21 VZ-M Turbo for airplane use !

I did something like this in the late '70s. I had a Veco .19, I put a Dubro boat cooling clamp on the head, I used a robart pump that used a tap of the crankcase for pumping action. I used 4 tubing lines, one for the carb, one for the muffler and one for the fuel to the head, the remaining one for the fuel to return to the tank. It worked great on my engine stand, I put a box from a vacuum tube I had laying around over the cylinder and the engine still ran strong, without the cooling setup the motor stopped within 5 seconds of putting the box over the cylinder. I sent the pictures to Don Typond at Flying models so I don't have them anymore though. Go for it it will work,
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