90L backplate mount  
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90L backplate mount - 6/17/2005 2:04:35 AM   
Rudeboy



Posts: 3256
Joined: 12/9/2002
From: Bejing, BELGIUM
Status: offline 		Hi Bob,

Could you tell me the diameter of a round backplate mount for the 90L? I want to know if it will fit in the nose of my AKM SU-27 Flanker.

Also, about the "LX" version of the .90: Has Dub been able to get some decent testing done on the engine? What does it turn on props like 11x8, 11x9 and 10x10?

Thanks in advance.

< Message edited by Rudeboy -- 6/17/2005 2:07:00 AM >

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Revver Brother #33
...I think it needs more power...
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RE: 90L backplate mount - 6/17/2005 3:28:27 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hey there.......

I will check the drawings and get back to you on the engine backplate mount dimensions. We have not sold one of these in a little while Outside diameter is about the same as a Dave Brown 60 size mount.

I do not see any reason why it would not fit in the SU-27. Would help move the engine aft about 1/2" or so. Although from looking at Rich's installation, the 'lines' of the front end tend to follow the longer beam mount fairly well. (one of these days I will actually get to finish building mine !!)

One thing to keep in mind, is that if you use the backplate mount, you will have to plan on mounting the needle valve on the airframe or firewall. I had considered for my aircraft, mounting the needle on the aft side of the firewall, exiting the cylinder side - can access it through the landing gear well if needed.

Performance wise, here is what we have found from our tests, and confirmed by some limited feedback

10 x10 16000
12 x 6 14900
11 x 8 15200
11 x 9 14700

(all APC props, 15% nitro)

Dub did have an 11x9 up over 15K for a while, and the 11x8 upwards of 15,500 too. Was a nice day out.

These are ground rpm. On an aircraft that will allow the engine to unload well in the air, it will really get-up-and-go.

There are only a handful of these out in the field so far, and we are still waiting on feedback from the owners as to how they were utilized in specific applications.

Should be able to pull an 11x10 or 12x7 well too after some run time.

The muffler is about 1" shorter than the standard 90L. Timing is pushed up 10 deg. The basic setup on this one, is to prop the engine to turn "over" 14,000 on the ground while still slightly rich (take-off mixture).

I will get back with you on the mount dimensions.

Bob

< Message edited by bob27s -- 6/17/2005 3:30:43 PM >


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Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Rudeboy)
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RE: 90L backplate mount - 6/17/2005 8:46:07 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		An update on the mount dimensions........

The mount is 2.500 in diameter, and it is .250 thick.

The bolt circle is 2.25", three bolts, round mount

It will not work on a fire engine because of the skirt of the piston.

After speaking with Dub I gathered up some of the pre-ship test info for several LXs on both the 11 x 8 and 11 x 9.

The best Dub has seen on a 11 x 9 is 14700 and the average is about 14400
(This is during pre-run before being shipped - still tight - needs some additional run time)

On the 11 x 8, the best Dub has seen is 15400 and the average is around 15000. Some turn 14800 or so.

Production rpm numbers are pretty much in line with the pre-production testing.

Perhaps of note to others..... If using an 90LX for a Great Planes Little Toni .....

.... you would want to order the engine specifying that installation - comes with the extensions and a modified muffler. On the 90LX "Toni" varient, Dub shortens the inside mini pipe another 1/2", which compensates for the added 1" of extensions. It drops off a few hundred total from the normal LX, but it is hardly noticable.

I trust this is useful

Bob


< Message edited by bob27s -- 6/17/2005 8:50:19 PM >


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Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Rudeboy)
       Post #: 3

RE: 90L backplate mount - 6/18/2005 4:34:35 AM   
Rudeboy



Posts: 3256
Joined: 12/9/2002
From: Bejing, BELGIUM
Status: offline 		OK, thanks Bob.

Those numbers on 11" props sound nice! After seeing Rich's video with a 12x6 on a standard 90L I was more or less convinced the Flanker could do well/better on something like an 11x8...Apart from the fake engine nacelles it is a fairly clean plane. He has got some very impressive vertical performance there (for a prop jet) That could be improved upon with somewhat less prop

I will check the plans to see if the rear cover mount will work... I prefer those over plastic beam mounts...

If and when I decide to go for the "L" or "LX", I'll make sure you guys get some "live" rpm numbers... (still pondering the question: is the AKM Flanker worth a 500$ engine...)

Thanks for the info, it is very much appreciated!

_____________________________

Revver Brother #33
...I think it needs more power...

(in reply to bob27s)
       Post #: 4

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> 90L backplate mount
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