Screaming Eagle Upgrade (310 HP with Scimitar Prop)

[Hank]

23 hours ago, aviatoreb said:

8 cylinders is so yesterday.  Everyone has 10 cylinders these days.

10 cylinders is so passé . . . Real aficionados all have twelve . . .

[aviatoreb]

Anyone remember the 5 cylinder BMW?

[Seth]

George-

Did you collect some good before data so you can compare the upgrade?  You are going to love the extra HP for ground roll and climb.

 

Take care,

-Seth

[Marauder]

Anyone remember the 5 cylinder BMW?

No but I remembered the Wankel.

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[Yooper Rocketman]

On 7/18/2016 at 5:48 PM, M20Doc said:

When it grows up, it will sprout the other two cylinders.

Clarence

Nah, when it grows it will have no cylinders!

 

[aviatoreb]

I always thought a wankel rotary should have been a good airplane engine.

 

[Guest]

22 minutes ago, aviatoreb said:

I always thought a wankel rotary should have been a good airplane engine.

 

It was tried in a number of Van's RV aircraft and never did well against Lycoming engines.

Clarence

[aviatoreb]

20 minutes ago, M20Doc said:

It was tried in a number of Van's RV aircraft and never did well against Lycoming engines.

Clarence

I have read - but I am unconvinced that it could not be made to work if the right purpose built aviation engine were designed, rather than a homemade conversion of a Mazda car engine.

[Yooper Rocketman]

10 hours ago, M20Doc said:

It was tried in a number of Van's RV aircraft and never did well against Lycoming engines.

Clarence

The treasurer to our local EAA Chapter tried one and by the time he converted to Lycoming after 2 years of nightmares his investment in the RV was double what it should have been.

 

[aviatoreb]

1 hour ago, Yooper Rocketman said:

The treasurer to our local EAA Chapter tried one and by the time he converted to Lycoming after 2 years of nightmares his investment in the RV was double what it should have been.

 

Yeah - I have read such stories.  Still - these are mazda car engines.  I have also read that it can be hard to get a subaru car engine to work well on an rv.  That does not disuade me from a horizontally opposed 4 cylinder fadec concept.  I think a purpose built aviation wankel rotorary could work - but unlikely to ever actually happen.

[jetdriven]

Subaru engines themselves are ok, but they wear out in 1000 hours, cost half as much, are heavier, far more complex with water cooling, electronic fuel injection etc, and they eat PSRU drives. It's like diesel airplane engines, in theory it works great, but nobody has managed to deliver a truly reliable example. 

The ravin comes to mind. Gear driven LS class Chevy V8 through a gear drive. 350 HP. But the ravin kept overheating, eventually it crashed and exploded.  Ffwd 4 years.  A RV10 builder at the same airport, CXO, has a Chevy v8 on his plane.  Keeps overheating. On downwind the thing gets really hot and the ECU goes into limp mode, fixed timing and fuel, drastically reduced power output. Nobody thought to ask about defeating that.  They crash it too, but manage to escape with their lives. 

Edited July 21, 2016 by jetdriven

[aviatoreb]

2 minutes ago, jetdriven said:

Subaru engines themselves are ok, but they wear out in 1000 hours, cost half as much, are heavier, far more complex with water cooling, electronic fuel injection etc, and they eat PSRU drives. It's like diesel airplane engines, in theory it works great, but nobody has managed to deliver a truly reliable example. 

The ravin comes to mind. Gear driven LS class Chevy V8 through a gear drive. 350 HP. But the ravin kept overheating, eventually it crashed and exploded.  Ffwd 4 years.  A RV10 builder at the same airport, CXO, has a Chevy v8 on his plane.  Keeps overheating. On downwind the thing gets really hot and the ECU goes into limp mode, fixed timing and fuel, drastically reduced power output. Nobody thought to ask about defeating that.  They crash it too, but manage to escape with their lives. 

Exactly the sort of thing I have read....

Personally, if I were building an experimental, I would go Lycoming, or Continental (or PT6, or Rolls Royce).

Auto engines - whether traditional or wankel, don't seem to do so well in airplanes.  But clearly piston engines that are purpose built can be quite good in airplanes, and I have a strong feeling that if it were not home-made engineers but a large firm with a clean sheet design and the funding to support it, then an aviation wankel could be designed and it would be fantastic.  This is very unlikely to ever happen.

[gsengle]

Remind me why a small, light, affordable, say 350hp turboprop can't be made?

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[carusoam]

The fixed conservative timing in limp home mode would be a real surprise when it comes to go around power.

It is probably a 10% difference in power.  Similar to O3 vs. O1 power differences.  

The 90's LT1 optical encoder used for precise engine timing has a wear /dirtiness issue.  It gets swapped out every 50k miles or approximately 1,000 hours.  (On the firebird, ) Requires removal of the radiator and water pump to access the distributor with the encoder mounted in it.  Yes, somebody actually mounted sensitive electronics under the fuel pump that has a weep hole to vent internal leaks.

Fortunately, you get a yellow light that indicates that something isn't right.  Today's electronics would tell you what isn't right.  I have a code reader that is often plugged in to verify the timing is working properly

The Ravin disaster was more of a gearbox issue.  A light gearbox is needed at the same time a really strong gear box is needed.

The firebird gearbox can be a chest crushing ordeal when swapping out a clutch, solo...  It also has a few extra gears in it's aluminum case.  Tremec-T6 is a nice gear box.  Have these people build your airplane transmission..?

Thought process...

1) select engine/prop combo.

2) select airframe.

3) refine or re-define mission.

4) repeat.

Experimental engine and gearbox combinations don't get the finances that are required to get developed properly.  This challenge gets exponentially bigger with the exponential increase in HP or torque.

350hp probably has 400-600 ft-lbs of torque which is technically Gobs of Power.  Trying to put a leash on it with a light experimental gear box would be a handful.

Did I mention that a really like my factory built airplane.  

I am looking forward to watching Tom's Turbine Take flight!

This is written from old fuzzy memories.  It may contain errors.

Best regards,

-a-

[Hank]

15 hours ago, aviatoreb said:

I always thought a wankel rotary should have been a good airplane engine.

 

They are available for model airplanes, just not as popular as pistons because the modelers don't understand how they work.

A purpose-built aircraft Wankel would probably be very nice.

[aviatoreb]

2 hours ago, gsengle said:

Remind me why a small, light, affordable, say 350hp turboprop can't be made?

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You want more than that - you want small, affordable, RELIABLE, and fuel efficient.  AS far as I understand the fuel efficient is the main problem.

You can buy a relatively cheap turbo prop for a toy RC airplane.

[jetdriven]

Turbines don't scale down very well. The SFC inherently gets worse as the engine gets smaller.  The P210 Silver eagle had a 300 something HP Rolls Royce turbine on it and it was pretty successful.  But it was a pressurized plane  

Edited July 21, 2016 by jetdriven

[Hank]

Because RPMs increase as turbine diameter decreases. We had one in the aerospace lab in college, a tabletop unit, that ran 30,000 RPM. it was bolted to the table, not a huge heavy one. 

[aviatoreb]

4 hours ago, jetdriven said:

Turbines don't scale down very well. The SFC inherently gets worse as the engine gets smaller.  The P210 Silver eagle had a 300 something HP Rolls Royce turbine on it and it was pretty successful.  But it was a pressurized plane  

Why couldn't that very same engine power a Mooney Acclaim?  With or without pressurization.

[GeorgePerry]

Apologies for un-hijacking the thread but here's a picture of the install in progress.  Test runs tomorrow.

 

[Hank]

2 hours ago, GeorgePerry said:

Apologies for un-hijacking the thread but here's a picture of the install in progress.  Test runs tomorrow.

 

Wow! Quick work! I thought you'd be down a month or so . . .

[roglaws]

What does it cost for the mod?

[co2bruce]

Looks good George, want to race?

[GeorgePerry]

The short answer is that it depends on if you need a 3 bladed prop or not.  If you need a 2700 rpm tachometer or not etc...etc.  Here's a thread that does talk about some pricing.

 

[carusoam]

G,

What are you going to use to measure the new flight characteristics?  

Do you have any new cool tools?  Anything interesting lying around the AOPA hangars for this?

Things that come to mind...

1) updated WnB.

2) T/O ground roll.  Near 800'

3) Climb rate.  Possibly 2 k'pm

4) keep an eye on the FF to make sure it is at the new high set point.

5) When set-up properly, the time to climb thread needs your update.  

Note: I used a SkyRadar to supply WAAS data to an IPad's CloudAhoy app.  CloudAhoy may cost a few bucks now to get the actual details out of it.  Byron photographed my vertical speed indicator in the climb.  Fun days ahead...

 

Best regards,

-a-