Quantcast

Raptor Composite Aircraft

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Status
Not open for further replies.

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
417
Location
San Rafael, California
The story I heard was Mike built a Viggen and did such a great job Burt hired him to answer the builder support phone. That allowed Burt to work on the next design.
.
This is pretty much what Burt said at Mojave last month.

That and something about D and F students taking all his time so he kinda pawned it off on Mike.
 

bmcj

Well-Known Member
HBA Supporter
Joined
Apr 10, 2007
Messages
13,529
Location
Fresno, California
they tend to lift up rather than change angle of attack like an elevator designed plane. I say this as the raptor kinda jumped the front wheel up rather than a level lift up
I’m not a canard expert (far from), but I suspect that has a lot to do with the landing gear configuration. If the mains are far aft and/or the nose gear is short, then some form of rotation will be required to achieve lift. If the nose gear is long, then it might fly itself off in three-point attitude if the canard is designed to stall before the main wing. Of course, ground effect might change things too.
 

xwing

Well-Known Member
Joined
Nov 4, 2019
Messages
81
Location
toronto
nov1/19
hmmmm ..don't recall this technique/method in the vids
https://www.homebuiltairplanes.com/forums/threads/raptor-composite-aircraft.24721/page-123#post-499620
Burt R. was a flight test engineer, and that's not the procedure he recommended in any of his POH's. In short, the recommended procedure was to accelerate to a particular speed (for the VE, it was 40 KIAS to start) and chop the throttle, then gradually add back pressure to see if the nose would rise. A gradual increase in IAS by 5 KIAS on each run, with a gradual application of back pressure after the throttle chop, gives a safe and non-surprising action of nose lift-off.
vs
https://www.homebuiltairplanes.com/forums/threads/raptor-composite-aircraft.24721/page-123#post-499625
Peter is slowly talking himself into flying the airplane personally, and that's been obvious, at least to me, for 3-4 months now. He swore from the beginning that he'd be using a "professional test pilot" for all the flight testing. He's rationalized doing taxi tests himself, and is now to the point of lifting off the nosewheel. Someone mentioned that he thought the mains came off on that last flight (I didn't see the video). If that's the case, and since "nothing bad happened," he's only one step removed from doing what he swore he wouldn't do, at the beginning.
Mighta missed but bottom line is the test pilot who turned down flight testing also didn't even end up doing taxi runs
 
Last edited:

AdrianS

Well-Known Member
Joined
Jul 5, 2014
Messages
571
Location
Australia
Just a thought !!!! with 99% of Peters YT followers blowing smoke up his a*se, maybe he can just float, like a Barrage Balloon, along the 5000ft runway, problem of test flying sorted ????
I don't think that's quite fair.
Peter's YT followers don't want to admit there are any (major) flaws in Raptor- that's not necessarily the same as worshipping him.
 

Bert

Well-Known Member
Joined
Mar 16, 2016
Messages
47
Location
Stony Plain
Firstly my response to the OP was in context, you have taken my reply to him out of context, but no problem, I'll answer anyway:
I didn't take it out of context. You used two terms in a way that I didn't understand so I requested clarification, noting more.

Correct, they are all 'Connercial Ventures', the difference is they proved or put their products on the market before they took public money, whereas Raptor has taken 2.7 million and continued on a path of doing everything except proving it.
I don't really understand this part. Peter isn't the first person in the homebuilt market to solicit funds to build a prototype and if it ultimately fails, won't be the first to have those funds blown on a non-viable project. That's the nature of the beast when you decide to crowd source an endeavor. Yes, I know that there are some who self fund their projects but they are the exception, not the rule.

I suspect there is 4 or 5 Members of this forum who would have had it flying a while ago with change to spare had it been under their wing.

Naturally I am unaware of how all of those companies got to be where they are, eg; their funding base, but if they also risked apparently naive people's money, then I am quite happy to critisise their methods also, as I have demonstrated in this thread recently with a similar project who did so.
If people want to pony up funds to create an assembly line to manufacture tin holes for teddy bears, more power to them. It's their money and their decision. Not to mention that there are more than a few "naive people" who are now millionaires because of their perceived naivete. No, i am not suggesting that there will be a whole crop of millionaires because of the Raptor project but stranger things have happened.
 

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
360
Location
Downham Market, Norfolk, UK.
I agree. Let's keep this about the airplane and the project, please, and not veer off into attacking Peter personally. Thanks.
OK guys sorry , to be honest I admire Peters passion for the project, its just I find it so frustrating when so many people, myself included, offer suggestions for problems he knows he has, the latest ReDrive video being a case in point. I simply cannot understand that he cant see the issue is the 'fixed Redrive' and 'floating engine' and the many YT suggestions, 99% having no idea what there talking about !!!!
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,796
Location
North Carolina
OK guys sorry , to be honest I admire Peters passion for the project, its just I find it so frustrating when so many people, myself included, offer suggestions for problems he knows he has, the latest ReDrive video being a case in point. I simply cannot understand that he cant see the issue is the 'fixed Redrive' and 'floating engine' and the many YT suggestions, 99% having no idea what there talking about !!!!
Yeah, you can't blame him too much for ignoring advice when the majority is from people who don't know what they are talking about. Look at all the advice to use crowned pulleys...
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,285
Location
Australian
Peter isn't the first person in the homebuilt market to solicit funds to build a prototype and if it ultimately fails, won't be the first to have those funds blown on a non-viable project.

That's the nature of the beast when you decide to crowd source an endeavor.
And? You act like the Raptor project is the first one I have vilified, and you would be far from correct. It just happens to be the current one.

Soliciating forward deposits is NOT crowdfunding, it is contractual obligation to supply said product.
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,511
Soliciating forward deposits is NOT crowdfunding, it is contractual obligation to supply said product.
How did this play out? His indiegogo campaign failed so he switched over to soliciting deposits? I agree, that is a different proposition.

I also think the proposed financing plan (see how I resisted calling it a 'scheme'?) sounds funny--several cash deposits before and during construction, and the customer begins making loan payments while the airframe is still being built (partly by the factory, partly by the the customer)? I can't imagine taking out a loan before the product (the raw "kit") has even been fabricated, let alone delivered.

Surely other facrory-assist type programs don't work this way? Wouldn't you pay up front for a "49%" airframe and assistance to complete it, rather than paying the factory to begin construction of your "49%" kit, and making paying interest until they get it complete enough for you to do your part? What remedy do you have if they don't deliver on schedule? (Remember, you're paying interest every month.) What happens if they go out of business? It looks like they have the money from the lender, you get no plane, and you have a huge loan left.

Technical issues aside, I would never sign up for such a program that places so much risk on the customer.
 

Hot Wings

Grumpy Cynic
HBA Supporter
Log Member
Joined
Nov 14, 2009
Messages
7,355
Location
Rocky Mountains
How did this play out? His indiegogo campaign
I had not known about this till just now.

"I have been flying for about 10 years and ever since I started I could never understand why all the small planes were so small. Why can't they be spacious like a car? "
<< >>
"So a few months ago I decided I would design my own with no initial intention of where that might lead."
<< >>
"The next requirement was it had to look cool."
<< >>
"Next I wanted a canard design because inherently they are faster than a conventional tractor design. "
<< >>
"OK, so that was the plan. Now the question remained, would I be able to design such an aircraft. I decided to try and just see what happened.

So as you can see below it turns out I can."


Explains a lot....But this is all history now.

I'm with Cheapracer in thinking that this is no longer about developing an aircraft with many flaws. It is about the end game for this project and hoping that it doesn't involve the exit of a human in the process.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,285
Location
Australian
Here's the complete text from the campaign.

Interesting reading, gives some insights.

How did this all start?

So I am a flight instructor who was born in Australia but I've been living in the U.S. for the last 20 years. I have been flying for about 10 years and ever since I started I could never understand why all the small planes were so small. Why can't they be spacious like a car? Over the years I have researched many planes but I couldn't seem to find one that had everything I was looking for in a plane. So a few months ago I decided I would design my own with no initial intention of where that might lead.

The first requirement was that it was roomy, like a mid size sedan or SUV with around 62" across at the pilot shoulders. I wanted to feel comfortable because I really like to do cross country travelling where you might be spending 4 hours on board. So I started with a virtual box which would outline the cabin space comfortable for 6'2" passengers and proceeded to create an aircraft around those dimensions.

The next requirement was it had to look cool. Most planes are ugly and you have to paint stripes on them just to attempt to make them look exciting. I wanted my plane to be sleek and sexy (no stripes necessary). So I started with a sleek shape. I wanted the windows to have the a wrap around effect, like my plane was wearing a cool pair of shades. I also wanted this effect without tricking anyone using paint. I knew it would be difficult, but possible, to construct a frameless window.

Next I wanted a canard design because inherently they are faster than a conventional tractor design. They call it a tractor because it's slow like a tractor :^P. In a tractor design the horizontal tail must generate downforce to keep the aircraft stable because the center of lift from the main wing is behind the center of mass. In any aircraft you need to be developing lift overall so creating downforce anywhere on the airframe seems like a waste of energy. A canard design has the center of mass between the main and fore wings and so both are generating lift to keep it stable. This is a much more efficient design. Also with a canard design the forward wing or fore plane is at a higher angle of attack and therefore will stall before the main wing. When this happens the nose simply drops a little and the fore plane begins flying again. Therefore it's not possible to stall the main wing. If the main wing can't stall then there is no way to spin a canard design and therefore they are safer. No ballistic parachute required.

Then I decided that I wanted to reduce drag wherever possible and go for a cruising speed at altitude of 300 knots true. At 25K feet this equates to 200 knots indicated. That's about 345mph or 556kph across the ground. Now we're going places! The sleekest airframes are composite construction (no rivets) so composite was the way to go. Obviously I would want to be able to pressurize it if I was going to be flying that high and composite construction also provides the strength required.

Next on the list was visibility. Most of the planes I have flown have the engine out the front and a high (too high) glare shield so the visibility out the front is nothing short of horrible. I wanted it to be like my car where I can see everything and the hood or dash are nowhere near my line of sight. For example, in a Cessna 182 the top of the glare shield is only 1 inch below my horizontal line of sight. I cant even imagine how someone shorter could fly that plane without sitting on a couple of phone books. Anyway, in my design the top of the glare shield is 6 inches below my line of sight, even lower on the passenger side. Not only that, the seats slide on an incline so shorter passengers will sit higher when they slide their seat forward. For a change your spouse will be able to see out the front and will enjoy flying even more.

The next consideration was how it would be powered. Most light aircraft use piston engines that burn 100 octane low lead fuel. This fuel is more expensive than other fuels and becoming even more so as it is considered a specialty fuel by the oil companies and eventually it will be phased out much like leaded auto fuel was. Diesel engines in aircraft are becoming available but they are heavy and require a lot of air for cooling. That air requirement creates drag. Recall that I am going for low drag. The ideal engine was a small turboprop. They burn jet fuel which is readily available (and will be for decades) and is cheaper than 100LL. So I did some research and found the Allison (now Rolls Royce owned) M250 series engines. They have been around since the 60's and are a reliable engine with a fuel burn of about 21 gallons an hour at altitude. So let's see, 345mph @ 21 gph works out to about 16 miles per gallon. Not bad considering you'll be taking 4 or 5 almost anywhere in no time. This is cheaper than driving if you factor in hotel overnight stays that are inevitable on longer trips.

OK, so that was the plan. Now the question remained, would I be able to design such an aircraft. I decided to try and just see what happened.

So as you can see below it turns out I can. Before you check out all the details let me finish the story. About 2 months into the design I figured it was a viable proposition so I decided to take a trip to Florida to visit a composite construction company that uses 5-axis CNC milling machines to make pieces and ultimately molds from a design like I have done. Everything was cool there and they can quite easily create the initial parts and then molds from those pieces. Using those molds, pieces can be created again and again. At this point I figured that it would be selfish of me to create only one of these planes so let's make molds and allow others to create the plane as well.

So the next step was to find someone to help me build it once the molds are ready. So I headed off to a composite shop, also in Florida, and after spending a day there and learning a lot I got on the web and did some more research and came across the website of a guy named Jeff Kerlo who had already designed, built and flown his own canard aircraft a few years earlier. My immediate thought was 'this is the guy I need to talk to'. So I gave him a call and an our later he called me back and we talked for about 3 hours. I showed him my design via the web page that I had created a week earlier and he was excited about it. Turns out he's back in Atlanta so the next morning I'm in the car headed North. I met with Jeff and he *IS* the guy and not only that, he wants to partner with me and create a company from this design. Turns out he planned to do the same thing with his aircraft but it did not work out for various reasons that are too detailed to go into here. Anyway, he already had figured out a 4 week in house initial build process and setting up a facility and tooling in Atlanta. So it seems like we were destined to meet and tackle this project.

So I spent a full day talking with Jeff and he gave me loads of ideas for changes and improvements to the design. Since then I have spent the last 4 weeks making all the changes and what you see below is the result of all that.

So now here we are, trying to raise the money to get started via Indiegogo. We think this design can really change what a small aircraft should be like but we need your help to prove this to the world. The question remains... will enough people think this is cool enough to want to be a part of it? We shall see. Thanks for reading my story.

If you want to learn more about Jeff Kerlo click here v-raptor.info

For even more details and pictures check out our website www.raptor-aircraft.com

Design Analysis and Drag Reduction

I have done a lot of flow modeling to ensure that the design does not create any unwanted disturbances that can result in dreaded drag.



This plot shows the vorticity or turbulence. I would still like to clean up the intake a bit but it was considerably worse on my first design.




Background coloring shows how the cabin shape accelerates the air thereby creating lift. The colors on the airframe show the relative air pressure distribution.



Background colors show surrounding air pressure and airframe colors show shear stress levels.



This plot shows air density distribution.


Area Rule Analysis of Airframe when compared with other designs


Although first discovered by a German, in the 50's a bright NACA engineer independently discovered the Area Rule and it was later used on the F102. Before the changes suggested by the Area Rule the aircraft was not able to go supersonic and afterwards it readily made Mach 1.2. All they did was modify the fuselage to have a coke bottle shape where the main wing was. That's a performance gain of close to 30%.




Here you can see the improvements that were made to the F102. Note that the cross sectional plot was improved but was still not ideal.

The cross sectional area transition smoothness that was achieved with the Raptor design is beyond what they achieved back then and will result in a major drag reduction, improved performance and greater efficiency.




The area rule plot shows that pressure changes are almost perfectly smooth as air flows from nose to tail. This design is a huge improvement over traditional tractor configurations. Compare this smooth bell curve with the plot from the Cirrus SR22 below.


As you can see from the chart above that overlays the cross sectional area over the airframe profile, the design of the Raptor results in almost a perfect area rule distribution. This means that instead of having pressure fluctuations as the air moves around the aircraft the pressure instead increases smoothly and decreases smoothly. This minimizes any turbulence and further reduces drag.

With a conventional tractor design there is a big jump in cross sectional area where the cockpit and wing begin and likewise a large drop where they end. Then you have another increase and decrease on the tail section, These abrupt cross sectional area increases and decreases on conventional aircraft create large pressure fluctuations which disrupt air flow creating turbulence and therefore create a lot of drag. This new design virtually eliminates this problem.




As you can see here the pressure fluctuations over the airframe of the Cirrus are dramatic. These cause turbulence and ultimately drag. It's called a 'tractor' configuration for a reason... tractors are SLOW.
Compare the area Rule distribution of the Raptor with this one of the Cirrus SR22. As you can see there is an obvious problem with this design. The widest part of the cockpit is in the same longitudinal position as the wing. This results in a maximum cross sectional area that is 33% larger (160 vs. 120 in the chart) than the Raptor. So even though the Raptor has a wider cabin than the SR22 it's maximum cross sectional area is way less, meaning it can squeeze through the air without having to displace as much air as what the SR22 does. This makes for a much faster and more efficient design.

You can read more about the Area Rule here http://en.wikipedia.org/wiki/Area_rule.

Cabin Space




The Raptor has, by far, more interior cabin space than any GA aircraft. The cabin is 62" across at both the pilot and back seat passenger shoulders. Compare that with only 49" for the Cirrus (even less in the back). Even a KingAir only has 54" of cabin width. Not only that but the back seats of the Raptor have just as much leg room as business class on an airline. The seats are cantilever suspended on carbon fiber braces allowing you to place your feet or bags underneath without the hassle of seat leg posts. This is truly state of the art design and ergonomics.



As you can see here there is as much space as your regular SUV. This pic shows the 4 seat option but you could just as easily install a bench seat in the back and carry 5 people.
There's no need risk falling by having to climb up on the wing to enter this aircraft. Just slide on in. The seat is at 32" which is higher than a car seat but lower than an SUV making it the perfect height for everyone to easily get in and out. The doors are 48" wide allowing easy access to the back seats.




As you can see from this cross section there is loads of space. These passengers are 6' tall. Notice the knee room for the rear passenger.



If we take the roof off (and part of one guy's head. ouch!) you can see again how much space there is. There's enough room for the back seat passengers to place their luggage on the floor next to them.

Of course if you wanted to put 3 across seating in the back the width at shoulder level is 61". That's definitely a comfy back seat for the kids.

There's also plenty of head room for even the tallest person. The seats slide on an incline and so as the seat moves forward it comes up. With the increased visibility of not having the engine out front even the shortest pilot will have a great view out front. The rudder pedal position will be adjustable so whether you're 5' or 6'5" the aircraft will feel like it was made just for you.



Side sticks allow precise and comfortable aircraft control while not blocking your view of the panel.



The instrument panel is designed to tilt back for easy access when installing or maintaining the avionics.



A great view for the pilot with the glare shield not blocking the view out the front yet everything on the panel is still readily visible. Note that the camera angle is somewhat tilted down for this view. The top of the glare shield is about 6" below your horizontal line of sight.



Copilot also gets a great view and will have an optional pop-up instrument or iPad panel that retracts to be hidden in the dash.



Even the back seat passengers get a great view out the front.



Specifications



Wingspan is just under 32' 9", length is just under 20' 7".



Excellent visibility for pilots and passengers. The rear seats are slightly higher and offset to the center.



Exhaust configuration for turboprop can also be used for piston option.



A single large intake where the airflow is the fastest provides for all the air requirements. This also reduces drag by not having multiple inlets and outlets.
The air intake will be channeled to provide intake air for the turboprop as well as cabin air. For the piston option it provides intake, cooling and cabin air. In the piston option the spinner diameter will be reduced to allow cooling air to escape. We are still in the process of designing a variable intake opening so just the right amount of air can be taken in.
 

Doggzilla

Well-Known Member
HBA Supporter
Joined
Jun 2, 2013
Messages
2,352
Location
Everywhere USA
Getting back to his potential test flight, there are two things he can do to greatly improve safety.

First, don’t stop on the runway. Launch using a rolling start off the taxiway.

This will reduce his run by several hundred feet, room that he will need for landing.

Secondly, make sure it’s cold outside. It will both accelerate more quickly and gain lift more quickly in the thick cold air. This will allow rotation several hundred feet earlier.

These two will give him at least 300-400 more feet of landing distance by freeing up takeoff distance.
 
Status
Not open for further replies.
Top