AC-Aero RV10 Hawk V4

genna

genna

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This is interesting. I wonder how much this engine costs.

http://www.ac-aero.com/hawkrv10/

Any RV10 builders consider this?

  • SAVE 100LBS over IO-540 D4A5
  • ADD 90HP over IO-540 D4A5
  • Burn JET-A instead of 100LL(my note: will run on just about any fuel out there including avgas and mogas)
  • Available as forced induction / E330J/G-T – 500hp
  • Weighs only 306lbs
  • Combined Cycle 2-Stroke Engine
  • Conventional 4 cycle wet sump lubrication
  • No valve gear
  • Compact low mass design
  • 3,000 hr TBO
  • Extended oil change periods (oil does not degrade)
  • Extended maintenance intervals (less parts to maintain)
  • Low part count for high life
  • Extremely high power to weight
  • Minimum vibration
  • Low noise and heat signature
 
First, it is a paper engine. Paper engines are always better than the real thing.

Second, it is liquid cooled. That adds complexity and failure modes and gives back most of the 100 lb claimed savings.

Third, I wouldn't buy the first of anything. Nor the 2nd or 3rd from a startup company. I'd want to see several in service with a thousand or more hours. That'll be a long time coming even if this engine is a world-beater.

Fourth, it is $80K. Because of #1 - #3, I'm not spending $80K on it.
 
kyleb said:
First, it is a paper engine. Paper engines are always better than the real thing.

Second, it is liquid cooled. That adds complexity and failure modes and gives back most of the 100 lb claimed savings.

Third, I wouldn't buy the first of anything. Nor the 2nd or 3rd from a startup company. I'd want to see several in service with a thousand or more hours. That'll be a long time coming even if this engine is a world-beater.

Fourth, it is $80K. Because of #1 - #3, I'm not spending $80K on it.
Click to expand...

1. Not exactly. It was on display in OSH 19. As I understand it it's been developed already(EAA's Sport Aviation magazine discusses it, this is how I found out) and is going to production sometime now(deliveries in early 21). But yes, until it is delivered to customers it is a paper engine.
2. Yes, adds complexity and better cooling and more power and bunch of other improvements over 50s technology. Which is the point of it. Obviously you don't agree that progress is useful on this front. The RV10 setup is complete with all the accessories. That's 100 lb lighter than IO540.
3. Company is 13 years old. They also have other products. Your other point is valid, however.
4. That is rather expensive.
 
nauga said:
What does 100lb off the nose do to the CG?

Nauga,
and the sum of some of the moments
Click to expand...

Quote from the EAA Magazine:
"Due to its lighter weight, AC-Aero is working with vendors to ensure components are placed to maintain CG and keep it as close to Van's stock specs as possible"
 
Longer motor mount will help a bit also. More room to work....
 
On the personal note. I don't get why people are afraid of liquid cooling. I understand a generally new design has people worried until it is proven, but I do not understand why liquid cooling by itself brings negative reaction. Liquid cooling has been around forever in cars and in planes. It has proven reliability and while it may add some level of complexity, it also provides many orders of magnitude better cooling efficiency and uniformity. Personally, I would trade a bit more complexity and mx for more power, less cooling issues, less cylinder replacements, less burned valves and less turbocharging issues.

Edit. It also does not add weight in larger engines. Air cooling requires metal fins and more oil, and oil cooler. More power - more, bigger fins, more oil, larger oil cooler. Bigger engine: more, bigger fins, more oil, larger oil cooler. All that adds quite a bit of weight.
 
genna said:
On the personal note. I don't get why people are afraid of liquid cooling. I understand a generally new design has people worried until it is proven, but I do not understand why liquid cooling by itself brings negative reaction. Liquid cooling has been around forever in cars and in planes. It has proven reliability and while it may add some level of complexity, it also provides many orders of magnitude better cooling efficiency and uniformity. Personally, I would trade a bit more complexity and mx for more power, less cooling issues, less cylinder replacements, less burned valves and less turbocharging issues.
Click to expand...
It adds another Single Point of Failure to the system. You get a leak in the coolant system and you have no engine. It's not a car that you can pull over and pour some water in to get you to a service station.

Every additional SPOF makes a system less safe.

I just helped a guy out a couple months ago that sprung a leak (maintenance induced) and rolled off the road nearby. A borrowed screwdriver and garden hose and he was back on the road. In an airplane, he would have been having a VERY bad day.
 
Salty said:
Longer motor mount will help a bit also. More room to work....
Click to expand...
I believe this is what they are doing in part as the stock cowling needs to be modified
 
Salty said:
It adds another Single Point of Failure to the system. You get a leak in the coolant system and you have no engine. It's not a car that you can pull over and pour some water in to get you to a service station.

Every additional SPOF makes a system less safe.

I just helped a guy out a couple months ago that sprung a leak (maintenance induced) and rolled off the road nearby. A borrowed screwdriver and garden hose and he was back on the road. In an airplane, he would have been having a VERY bad day.
Click to expand...

First, that's not true. You can run engine with no water at reduced power for some time. Certainly long enough to land. I've had that happen in a motorcycle and nothing blew up. Second it adds one point of failure but reduces the chances of all the ones associated with air-to-oil cooling overheating which is a lot more "explosive" and terminal.
 
genna said:
First, that's not true. You can run engine with no water at reduced power for some time. Certainly long enough to land. I've had that happen in a motorcycle and nothing blew up. Second it adds one point of failure but reduces the chances of all the ones associated with air-to-oil cooling overheating which is a lot more "explosive" and terminal.
Click to expand...
Hope you notice it instantly and reduce power. I think odds are you won't notice until it's too late to "run long enough to land". We disagree on this one.
 
Salty said:
Every additional SPOF makes a system less safe.
Click to expand...

This statement is patently wrong. 70's VW vs Honda is all you need to show that.

Edit. You don't even have to go that far back. Take Harley and a similar Honda. Harley is simpler for sure, but if dependability is your only criteria, Honda is a clear winner. Extra performance and less weight is just a bonus here
 
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Salty said:
Hope you notice it instantly and reduce power. I think odds are you won't notice until it's too late to "run long enough to land". We disagree on this one.
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Really? This is your point? Are sensors really that difficult to add? Overheat protection is trivial. The best thing here is even if you overheat, the engine doesn't blow up. The temps are not there to melt it. It cools down and can be restarted in a critical phase closer to the ground.
 
genna said:
1. Not exactly. It was on display in OSH 19. As I understand it it's been developed already(EAA's Sport Aviation magazine discusses it, this is how I found out) and is going to production sometime now(deliveries in early 21). But yes, until it is delivered to customers it is a paper engine.
2. Yes, adds complexity and better cooling and more power and bunch of other improvements over 50s technology. Which is the point of it. Obviously you don't agree that progress is useful on this front. The RV10 setup is complete with all the accessories. That's 100 lb lighter than IO540.
3. Company is 13 years old. They also have other products. Your other point is valid, however.
4. That is rather expensive.
Click to expand...

1) It is a paper engine until it is flown and in customer hands. Show me an engine. Show a flying installation. What is in SA or in a booth at Oshkosh is neat but mostly irrelevant. I've seen dozens of things in both that never came to fruition.

2) Can you show a spec that explicitly claims the cooling system, including radiators is in the spec'd weight? I can't find one. The one I *can* find explicitly excludes numerous accessories from its weight.

http://www.ac-aero.com/wp-content/uploads/2020/05/ac_hawk_2020_R00_040720.pdf

BTW, I'm all for progress. I'm not a fan of businesses which advertise products that are "almost ready". That makes my spidey senses tingle. I'm proud I wasn't an early adopter of Blue Mountain Avionics <to list but one> back in the day...
 
genna said:
First, that's not true. You can run engine with no water at reduced power for some time. Certainly long enough to land.
Click to expand...

You're right. We haven't left one up there yet. You always have plenty of power to get back to the ground. ;-)

Seriously, the hole in the radiator quickly brought down hundreds, maybe thousands of liquid cooled aircraft during wars. Not that you can't have reliable liquid cooling, but removing failure points from the system (like radiators, hoses, water pumps, seals, etc) is always a good thing.
 
kyleb said:
You're right. We haven't left one up there yet. You always have plenty of power to get back to the ground. ;-)

Seriously, the hole in the radiator quickly brought down hundreds, maybe thousands of liquid cooled aircraft during wars. Not that you can't have reliable liquid cooling, but removing failure points from the system (like radiators, hoses, water pumps, seals, etc) is always a good thing.
Click to expand...

And thousands Rotaxes fly every day. And million of cars drive every day without blowing up or blowing their pistons out(seem to be a fairly common occurrence in our engines)
 
kyleb said:
1) It is a paper engine until it is flown and in customer hands. Show me an engine. Show a flying installation. What is in SA or in a booth at Oshkosh is neat but mostly irrelevant. I've seen dozens of things in both that never came to fruition.

2) Can you show a spec that explicitly claims the cooling system, including radiators is in the spec'd weight? I can't find one. The one I *can* find explicitly excludes numerous accessories from its weight.

http://www.ac-aero.com/wp-content/uploads/2020/05/ac_hawk_2020_R00_040720.pdf

BTW, I'm all for progress. I'm not a fan of businesses which advertise products that are "almost ready". That makes my spidey senses tingle. I'm proud I wasn't an early adopter of Blue Mountain Avionics <to list but one> back in the day...
Click to expand...

It was mentioned in EAA magazine
 
kyleb said:
You're right. We haven't left one up there yet. You always have plenty of power to get back to the ground. ;-)

Seriously, the hole in the radiator quickly brought down hundreds, maybe thousands of liquid cooled aircraft during wars. Not that you can't have reliable liquid cooling, but removing failure points from the system (like radiators, hoses, water pumps, seals, etc) is always a good thing.
Click to expand...

Seriously, you are defending a cooling system that exists only in lawn mowers and piston airplanes(and a few motorcycles stuck in the past). Nobody uses it and reliability has improved tremendously . This along should tell you something.
 
genna said:
It was mentioned in EAA magazine
Click to expand...

Yes. Sport Aviation (SA, as it were). A wonderful magazine. I love it and read it cover to cover every month.

There have been a gazillion things in SA that have been listed as "Coming Soon". Yet they never did. See: Bede 12 and 14 as references. SA is an enthusiast magazine, not 60 Minutes, and doesn't go to tremendous lengths to vet its stories.

An acquaintance of mine got a 1/2 or full page article about his homebuilt/turbine helicopter in there several years ago as part of a SnF (That's Sun N Fun) report. One of his quotes in the story was: "The helicopter has lots of hours". The truth was he trailered it down there because he hadn't finished the Phase 1 fly-off time. His Phase 1 testing had been hampered by the crash when the tail rotor driveshaft broke. ;-) That wasn't mentioned in the article either. Not because of any malfeasance on the part of SA, but because the guy was trying to get publicity to commercialize his project and didn't volunteer anything that wasn't favorable to his product. <I had a phone conversation with the editor of SA about that one. He seemed pretty unhappy that they'd been hoodwinked.>

Take everything you read, not just in SA, but everywhere, with a grain of salt.

Oh, and show me a spec sheet that shows the cooling system and accessories are included in the "100 pounds lighter than a lycoming" weight. The one I found (and linked) doesn't say that, and the website doesn't state it either. They are surprisingly vague if that's the truth and a selling point.
 
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kyleb said:
Yes. Sport Aviation (SA, as it were). A wonderful magazine. I love it and read it cover to cover every month.

There have been a gazillion things in SA that have been listed as "Coming Soon". Yet they never did. See: Bede 12 and 14 as references. SA is an enthusiast magazine, not 60 Minutes, and doesn't go to tremendous lengths to vet its stories.

An acquaintance of mine got a 1/2 or full page article about his homebuilt/turbine helicopter in there several years ago as part of a SnF (That's Sun N Fun) report. One of his quotes in the story was: "The helicopter has lots of hours". The truth was he trailered it down there because he hadn't finished the Phase 1 fly-off time. His Phase 1 testing had been hampered by the crash when the tail rotor driveshaft broke. ;-) That wasn't mentioned in the article either. Not because of any malfeasance on the part of SA, but because the guy was trying to get publicity to commercialize his project and didn't volunteer anything that wasn't favorable to his product. <I had a phone conversation with the editor of SA about that one. He seemed pretty unhappy that they'd been hoodwinked.>

Take everything you read, not just in SA, but everywhere, with a grain of salt.

Oh, and show me a spec sheet that shows the cooling system and accessories are included in the "100 pounds lighter than a lycoming" weight. The one I found (and linked) doesn't say that, and the website doesn't state it either. They are surprisingly vague if that's the truth and a selling point.
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Point taken. Everything in aviation should be taken with quite a few grains of salt until(and sometimes even after) it actually exists and sold to customers. As I replied to your original post, it *IS* a paper engine until it is being sold to customers. And specs are only going to matter then. There something about their build center(ASAP) on their site. Perhaps you can give them a call and find out more details.
 
genna said:
Point taken. Everything in aviation should be taken with quite a few grains of salt until(and sometimes even after) it actually exists and sold to customers. As I replied to your original post, it *IS* a paper engine until it is being sold to customers. And specs are only going to matter then. There something about their build center(ASAP) on their site. Perhaps you can give them a call and find out more details.
Click to expand...

I don't need info from their build center. My RV-10 is 99% complete. ;-)
 
No one mentioned getting rid of the entire valvetrain seems to eliminate a few points of failure. No rods to bend, valves to get stuck, etc. I’ve always liked 2 stroke engines. I’ll never be the first one to test out a new motor for an airplane. But I won’t count it out!


Sent from my iPad using Tapatalk Pro
 
I don't want to be the first, however interested in seeing how well this works out.
 
There is a 12 page discussion in the Van's forum about the AC Aero Diesel. It however ends rather abruptly with the guy, who was working on installing it in his RV10, stating that he is "no longer affiliated with the development of a RV-10 firewall forward kit for the AC-Aero Diesel engine".
https://vansairforce.com/community/showthread.php?t=167537

He might be a good person to talk to, if anybody is interested in this engine.
 
I'm only at the empennage stage of my RV-10, but I'm certainly interested in innovative alternatives to the Lycoming standard. Here's hoping AC-Aero can deliver on their hype and put real hardware in real-world aircraft long before I mount the engine in mine.
 
Lloyd Mangnall said:
I'm only at the empennage stage of my RV-10, but I'm certainly interested in innovative alternatives to the Lycoming standard. Here's hoping AC-Aero can deliver on their hype and put real hardware in real-world aircraft long before I mount the engine in mine.
Click to expand...

Get with the Raptor guy and check out the Audi auto conversion...
 
Lloyd Mangnall said:
I'm only at the empennage stage of my RV-10, but I'm certainly interested in innovative alternatives to the Lycoming standard. Here's hoping AC-Aero can deliver on their hype and put real hardware in real-world aircraft long before I mount the engine in mine.
Click to expand...

I predict if you are willing to pay 3x the cost of an IO-540 you can buy an engine virtually no one else has that no mechanic will ever go near.
 
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