Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Jett 46 or 50

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Old 08-23-2005, 09:17 PM
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Default Jett 46 or 50

I've been flying a Patriot kit built for the past two years with a 46FX and want to move it into the 100+ speed range. With the O.S., I don't think I breaking 80mph. Just wondering if anyone with Jett engine experience can tell me if I will see much of a top speed difference between the Jett 46 and the 50. Thanks.

Marty
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Old 08-23-2005, 10:01 PM
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Default RE: Jett 46 or 50

go with the .50, no substitute for cubic inches

according to webpage you get 500 more RPM

the SuperSport: single needle carb yeilds 300-800 more RPM

a tuned pipe adds more power-+-RPM

I have 3 .50 2-sport and 1-FIRE, a SS40 and a 1.20


ask bob27 about a 61LX
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Old 08-23-2005, 10:18 PM
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Default RE: Jett 46 or 50

Marty I have flown Patriots with engines ranging from an ASP-46 (OS clone) up to a Jett-50 and the answer is:

Yes! You will notice a HUGE difference in speed and vertical performance- Think Toyota Tercel VS Dodge Viper

And yes, per Bob27 the difference between the 46 and 50 is only about 500RPM's
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Old 08-24-2005, 08:03 AM
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Default RE: Jett 46 or 50


Thanks Bob, James....

As noted, if you are looking for an upgrade from an OS46, either the SJ-46 or SJ-50 will make you happy.


Marty,

Is your Patriot set up with fixed gear or retracts ?

The OS .46 is a pretty decent engine. What muffler are you using? What size prop ?

Bob
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Old 08-24-2005, 08:57 AM
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Default RE: Jett 46 or 50

Hi Bob,
The Patriot has mechanical retracts, drag causing simulated side intakes, and I believe I was using an APC 10 X 7 prop. I had at one time put on the tower muffler which gave me a kick in RPM and speed but the midrange was poor and I had two deadsticks so I switched it back to the stock muffler. I probably just needed to fine tune it and maybe go to a smaller prop but I just wanted to fly it without worrying about the engine dying while slowing down on final approach. I think I tried a smaller diameter prop at one time but I could barely get the plane moving fast enough to get it off the grass? I haven't tached the engine since last year and I can't remember what I was getting but it was normal for an O.S. 46 with the prop I had on it. I know I will get quite a speed boost going to a Jett 46 or 50. I was just wondering if the stated extra 500 RPM on the 50 is going to be noticable in the top speed? Thanks

Marty
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Old 08-24-2005, 09:54 AM
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Default RE: Jett 46 or 50

Thanks for the info.

Chances are when you switched to the tower muffler, the 10x7 prop was too big - did not allow the engine to get up into that 15K rpm range where the muffler works... and that contributed to the midrange issues.


ummmmmmmm...... my guess is you will never notice the difference on the top end speed with either engine. The 500 rpm does represent a significant increase in power, and on an clean airplane its going to add up to a handful of MPH, but on the patriot its going to be more like 4-5 mph difference.

Flying with a standard 10x6 prop, the SJ-50 unloads about the same amount as the SJ-46 in the air so the differnce is still only 500-600 rpm or so. They use the same muffler, and you have to turn within the same rpm range. Prop either to run between 16K and 17.5K peak rpm on the ground, and launch 400 - 500 rpm down. The SJ-50 can usually turn one size larger prop a bit better.

If you are looking to save a few $$ with the SJ-46, its is probably a good way to go.

When you get down to speed props, the .46 prefers a 9x7 or 9x8 where the .50 would use a 9x8 and can turn a 9x9 after some run time.

If you want insain speed, the SJ-60LX (same size as the .46 and .50) turns a 10x6 over 18K rpm. [8D]

There is one guy out there using a clipped 10x10 prop on the 60LX and a patriot. I have not heard back. His bench RPM numbers sounded good though.

I trust this addresses your question

Bob
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Old 08-24-2005, 10:30 AM
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Default RE: Jett 46 or 50

Bob,
Thanks. This pretty much answers my questions. Just need to decide which one to go for and get the CC out and place an order.

Marty
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Old 08-31-2005, 10:42 PM
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Default RE: Jett 46 or 50

repeat post.
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Old 09-01-2005, 08:12 AM
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Default RE: Jett 46 or 50

Ok guys,
Just received my Jett 50 for my Patriot and I didn't think about the muffler needing an extension. I see that the mounting pattern for the muffler is the same as the O.S. and I'm wondering if an O.S. muffler extension would work ok and let the engine "breathe" properly seeing as though the exhaust openings are a bit different dimension wise? Thanks.

Marty
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Old 09-01-2005, 09:11 AM
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Default RE: Jett 46 or 50

First, the bolt pattern does not match the OS bolts.

You can get extensions from Dub if you require them. Either 1/8" or 1/4", and use the gaskets as well. Use as very little as possible, since this affects the tuning length.

However, I do not recall needing any exhaust extension on my own Patriot .40 installation - muffler and engine fit well.

Here is an example. Its close, but generally it fits ok

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Old 09-01-2005, 09:55 AM
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Default RE: Jett 46 or 50

Hi Bob,
Thanks for the info. I just matched up the o.s. to the engine and realized they don't line up. I need close a 1/4" to clear the bottom of the fuse. Maybe mine is a little "fat". Yours looks like you built it around the Jett. Since mine was built around the 46FX, I had to start chopping away at the top of the nose ring and the bottom just to get the engine in. Quite a PIA. Hope it's worth it. Now I have to wait another week for a muffler extension[&o]. Thanks again.

Marty
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Old 09-01-2005, 01:39 PM
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Default RE: Jett 46 or 50

Let me know how you make out.

Mine was one of the original ARF versions. Fit in there ok if I recall. I guess its all in how you sand and round off the front end. It is a close fit.

You have to cut away near the nose ring? To clear part of the carb I'd imagine ? The rest of the engine is the same bolt in, spacing and footprint size.

If you end up with 1/4" of spacer you will be ok. After break-in on a 9x6 (per instructions), use a 10x6 or 9x8 for the first handful of flights, and with the spacer you will have no trouble pulling a 9x9 or 10x7 after about 30 minutes of air time.

BTW, the Jett muffler bolt spacing is the same as a ST40 and Webra .40

Bob
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Old 09-01-2005, 02:39 PM
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Default RE: Jett 46 or 50

I just picked up some 1/4" aluminum barstock. See if I can't make a spacer. Yeah, the carb was preventing me from getting the engine in. Mine is from a kit and when you are building the engine bay, you have your engine mounted and it dictates the angle of the side cheeks. Also, the throttle arm with the z type bend was way too far away from the engine. It actually would end up outside the plane if I used it as it came out of the box.

Marty
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Old 09-01-2005, 04:23 PM
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Default RE: Jett 46 or 50

bend the throttle arm as deired. It is soft material just for that reason. I bend mine back against itself a bit to shorten the throw.

if you make your own extension, just be sure the mating surfaces are flat. Exhaust gaskets are a must. A leak at that muffler joint will drive you nuts after a while (engine will run weird, and black crap everywhere).
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Old 09-01-2005, 05:55 PM
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Default RE: Jett 46 or 50

I bent the throttle arm and shortened it up.

Is that gasket that comes with the engine made out of brass?

I finished the extension. It gives me a little more than enough clearance. Not too bad since all I used was a hacksaw, drill press and a dremel tool. It ain't pretty but I hope it works ok.

Where did you mount your need valve on your Patriot? I can't see it in the pic.
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Old 09-01-2005, 09:26 PM
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Default RE: Jett 46 or 50

Hey, that looks mighty good It will work just fine.

The gaskets are brass. No need to make a special one. Try with just the one you have for now. Put that one between the case and your extention (just like you have it there)

On my patriot I had the needle mounted on the firewall behind the engine exiting the top of the plane.

On this photo (not my plane) Im not entirely sure how he installed the needle assembly. From the plumbing, it is either mounted on the backplate with the needle running up behind the cylinder (needle hidden) or he has it on the firewall and its exiting the other side of the cowl. Id wager its on the backplate. Nice thing about it, is you can mount it on the engine, firewall, where ever you wish.

From your photo there, simply mount it on the backplate, and let the needle exit the top of the fuselage through the slot where the OS needle did

Looks like a nice navy finish on there
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Old 09-01-2005, 11:28 PM
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Default RE: Jett 46 or 50

Thanks for the assistance and advice. Hopefully I will get to break in the engine tommorow and fly it on Saturday.

When I was building the kit, I thought the Jolly Rogers scheme would look good. It looked better in my mind than it does on the plane though.

Marty
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Old 09-01-2005, 11:30 PM
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Default RE: Jett 46 or 50

Tight fit indeed... Nose-ring? Mine was hacked back a bit to fit the carb. as Bob mentioned-

I forced my SJ-50 into the 50SX holes as I recall---

My muffler hits the fuse, so how hot do these mufflers get?

You guys run a RNV on the SJ-50? Come on get your fingers up there by the prop.... LOL

Cheers!
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Old 09-02-2005, 12:14 AM
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Default RE: Jett 46 or 50

Razor,
Looks like with both did our fair share of hacking.

I wish I got mine with the needle on the carb. With the RNV mounted on the backplate, I couldn't push the engine far enough back to line up with the existing holes from the 46FX. I could hack away at the engine mount where the RNV hits it but I would have to get rid of a lot of it to get the engine to sit where it should. I might mount it on top of the motor mount if I cant find a better place. How much faster is your Patriot with the Jett compared to O.S.?

Marty
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Old 09-02-2005, 08:10 AM
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Default RE: Jett 46 or 50

It will get a bit hot. If it is just barely touching, it should not be a problem. If its really hitting, you may want to relieve the fuselage (or dent in the balsa) a bit. If its really snug on the fuselage, it might induce as weird vibration into the system and there is a risk to break the muffler bolts.
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Old 09-02-2005, 03:02 PM
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Default RE: Jett 46 or 50

Bob,
Can you tell me what is the thread on the backplate screws. I can't seem to find a die SAE or metric that fits. I need to shorten the one up that is holding the RNV as I'm going to mount it elsewhere and I want to clean it up. Thanks

Marty
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Old 09-02-2005, 03:23 PM
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Default RE: Jett 46 or 50

Should be 5-40

you should not have to shorten it... i seem to recall there is enough thread depth in there. (Perhaps Dub has a longer screw in there now ?) I could be wrong.
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Old 09-02-2005, 03:59 PM
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Default RE: Jett 46 or 50

Razor,

the Jett .50 is the only engine that has ever "bit" me good. That needle is pretty close to the prop, and I will be getting a remote for the engine. Just happened about a month ago, thankfully I was behind the prop and it only took off several layers of skin by my thumb. Just about healed, but painful.
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Old 09-02-2005, 08:32 PM
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Default RE: Jett 46 or 50

5-40? Never used one of those. I've gotten along all these years with 4-40,6-32 and metric stuff. Thanks.

Marty
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Old 09-02-2005, 09:11 PM
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Default RE: Jett 46 or 50

Afterburner- My original Patriot with the ASP-46 (OS clone) flew okay (75MPH?) I hate guessing speeds- But the Jett-50, 9x9 apc on 15% is a 125MPH airplane...

Night and day difference! Trust me-
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