22 Dec 2025, 16:23 [ UTC - 5; DST ]
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Username Protected
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die  Posted: 24 Oct 2019, 11:00 |
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Joined: 08/26/15
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Company: airlines (*CRJ,A320)
Location: Florida panhandle
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Username Protected wrote: 80+mph for hours at a time (pretty common for a family sedan with a four cylinder or a small six), getting 20-25mpg, that's 3-4gph and a lot more than 20hp. If running LOP, 3gph is 3 x 14.9 = 45 hp. True, that’s more than 20 hp but with a 200 hp engine it’s only 23% power. My pickup burns 3.5gph at highway speeds. With 250 hp under the hood, that’s about 20% power.
Just a counterpoint, but rather than looking at it as an expression of peak horsepower, I like to think of it as a comparison of continuous output for a given displacement.
45hp from 120-150 cubic inches (i.e. four cylinder in a late model Camry-Accord)
100-120hp from a Lycoming 360 (8,000' and 2200-2400rpm).
130-160 from a Continental 470 or 200 from a 520 or a 550...
My only point is that the old wisdom, that auto engines don't have to work all that hard, isn't really true any more. The disparity is a lot less than it seems and the auto manufacturers got their acts together much better than they used to do.
As far as how well they hold up in service, there is definitely a spotty track record between different make/model/year as some auto manufacturers have built to a price point instead of a quality point... lots of auto engines suffer an early death before 100,000 miles but there are also a lot that still give good service between 200-300,000 from simply following basic maintenance.
Plenty of aero engines last 2000+ hours on routine maintenance but there are also a lot that need major maintenance before 1,000 hours... because the manufacturer had a run of low quality components (cough valve guide wear) or mistakes during casting of assembly that result in case cracks or head cracks after only hundreds of hours... but none of that speaks to inherently poor general durability of aero engines. Similarly, there are examples of specific auto engines that have "there's a service bulletin for this" problems, such as cheap timing chain guides that cause an otherwise good engine to self destruct, or blown head gaskets when the real reason is the bean counters and engineers used head bolts with not enough threads to maintain enough clamping force... but again, that doesn't mean that all auto engines are too fragile to be run hard in service.
(All that said, there are still some auto engines that aren't up to the task of making good, hard highway runs day in and day out for years. I just don't think it's a good rule of thumb to dismiss all or even most auto engines as not durable.)
Back to the topic at hand, the horsepower requirements and goals of this powerplant in question seem, uhhhhh, let me use the word "ambitious."
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 24 Oct 2019, 12:02 |
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Joined: 03/15/16
Posts: 441
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Location: NC
Aircraft: Looking for one
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Really, I don't think the TDI is going to be a problem. I'm not sure about that redrive system. I would think you want it moving with the engine. I wouldn't want the engine movement changing the tension on those belts.
From his latest video, it does look like he has gotten more power out of the engine. I'm not sure if he is going to wait for the test pilot though if he keeps getting it faster and faster.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 24 Oct 2019, 18:18 |
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Joined: 10/06/19
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Company: Water Cleaners
Aircraft: Pilatus PC-12 NG
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Username Protected wrote: Chris
Not sure what your problem is?
I in fact do have experience with marine and auto engines. How many marine engines have you built? I owned a marine and auto performance shop. I literally tune engines all the time. I have gone through the process Peter is going thru many times. How many days have you spent on a dyno tuning a engine?
Answer me this, what qualifications do you have to tell me that I don’t know what I am talking about? Tell me again what claims I made that were outrageous and I will take the time to prove what I have said. Let’s go ahead and go down this road since now you are making it personal.
Mike Let's take this one piece at a time Mike. Can you show me a reference on bearing clearance being different in marinized vs OEM auto engines? Will be the first I have heard of it. .... but I repeat myself.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 24 Oct 2019, 22:00 |
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Joined: 03/15/16
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Location: NC
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The only things I’ve seen done different on marine engines are corrosive resistant head gaskets, marine specific water pumps and accessories and different cam spec’d for marine use. Many are closed loop systems now. I know the PCM and Indmar run a few thousand hours.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 08:51 |
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Joined: 09/04/09
Posts: 6203
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Location: Doylestown, PA (KDYL)
Aircraft: 1979 Baron 58P
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Username Protected wrote: There should be a pool for which of the Raptor’s predictions will fall first. The $130k? The 300 kts? 1500 lb? 3600nm? My guess is....All of the above. But if he gets within 20% of his goals, it would be an awesome airplane.
_________________
Rick Witt
Doylestown, PA
& Destin, FL
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 09:42 |
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Joined: 08/10/14
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Location: Northwest Arkansas (KVBT)
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Username Protected wrote: Weight is everything.
Put it on a diet and it will climb better.
How much weight loss is reasonable from a first prototype to second prototype to a production kit?
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 10:02 |
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Joined: 05/01/14
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Location: Операционный офис КГБ
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Username Protected wrote: Chris
Sorry to be part of this thread drift. Really need to drop this convo and back to the topic.
Really no benefit for either of us in this discussion. Unless maybe you or I are going to start selling marine engines. Haha. I know I am not.
Mike Mike, Via my dad, I have been involved in replacing two boat engines. One was on a Ski Nautique; and yes this was a "customized" engine. The other was in a Chris Craft. For the Chris Craft, they literally bought a crate engine from GM. Nothing custom about it. Tim
GM sells Marine specific crate motors. I bought one last year. They are not radically different from a truck motor, except many are reverse rotation, and sure you can get away with a regular car version for the load and number of hours most boaters put on them, but you won’t see a 2000 hour TBO.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 10:11 |
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Joined: 05/01/14
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Username Protected wrote:
Let's take this one piece at a time Mike. Can you show me a reference on bearing clearance being different in marinized vs OEM auto engines? Will be the first I have heard of it.
.... but I repeat myself.
You evaded the question about your background and qualifications.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 10:15 |
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Joined: 05/06/14
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I think that he is attacking too many things at the same time.
First, I would have a proven the flying body ( using a proven powerplant) Kinda important to know if that thing is going to fly, and what kind of issues do I have with that frame... Given to fact that he has no access to a wind tunnel, the design as just that, a design.
Once that is done, I would have gone after the engine, and try to refine that. Lots of people out there fly around with auto engine, modified. It's doable. Making it reliable is a complete different task.
But at least get the "Plane" side of the equation taken care off.
This is not like going down the street to give it a try, come back to retune, and do it again.
The first time you fail... Lots of things on the line, including your life...
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Grumman Tiger 78
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 10:27 |
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Joined: 05/01/14
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Location: Операционный офис КГБ
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Username Protected wrote: There should be a pool for which of the Raptor’s predictions will fall first. The $130k? The 300 kts? 1500 lb? 3600nm? He already failed the 1500 lbs. Missed that one by a lot! 3600 nm range is possible if you just fill it with enough fuel and just a single pilot and fly slow with a tail wind. It sure won’t do that with 4 or 5 seats filled with 150 lb adults and at higher cruise speeds. 300 kts is possible by “simply” adding more power, but not at fuel burns he is thinking about and the power plant that can do it isn’t going to have the 12 hour endurance to get you a 3600 mile range. At least not with the weight of fuel those wings can safely lift. Has he mentioned a minimum flying speed (canard stall) yet? At the empty weight he is realistically looking at, plus 4-5 people and the fuel load, this thing is going to need LONG runways and fast landing speeds. Engine out near gross weight? YIKES!
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 25 Oct 2019, 10:41 |
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Joined: 05/01/14
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Username Protected wrote: Given to fact that he has no access to a wind tunnel, the design as just that, a design Wind tunnel access is available if you make the effort to pursue it. Even better, CFD software, and if needed consulting services, are widely available. Normally you would do much of the design testing with CFD and if appropriate, final verification in a wind tunnel. Changing shapes in CAD is a lot quicker and cheaper than building scale models, and models are a lot quicker and cheaper than full scale prototypes.
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