Not trying to be combative, but as a pilot I have to ask: What is the reason for the high-altitude turbo setup if you can't use full power to climb more than 1000ft out of the pattern? Does anyone know if the advice of the VW/Audi-Turbo Diesel designer in previous video's comments section (I think it was Andres somethingornother) has been followed to see if eliminating a turbo would help with the heat? Id love to see this project succeed but it seems like it might be better to set up for low altitude ops until the aerodynamics are sorted out doesn't it? I guess i'm thinking more along the lines of get it to fly well in the current flight envelope before setting up for high altitudes... or better yet, set this one up for low altitude to collect data and then Raptor Prototype v2.0 can focus on weight savings in the build and high altitude performance in the powerplant... regardless, God's blessings in your endeavors and be safe out there!
That seems a little short sighted. Solve the heating issue (Which plagued all of the P-51, B-29, B-17. P-38, and a "few others" during development) and it is a non issue. One thing at a time.
I think for the most part, the issue with not being able to use much manifold pressure is due to inadequate cooling. Once that's figured out then full rated MP should be attainable. Usually, the big problem with a turbo aircraft is figuring out the right balance between proper cooling at low speed/climbout and lowing cooling drag penalties at high speed.
I have been following this development almost since inception but I am wondering if we will ever see some decent airspeed on this machine. In my opinion, the powerplant cooling issue should become a high priority because honestly, for a small comparison a SLING TSI with 135 HP Rotax can cruise at 150+ kts on 7.5 gph up to FL180. What will the Raptor offer to rival that?
You're not going to see higher speed testing until other parameters have been met. No sense in adding another unknown factor into the testing regime until the known issues are addressed first.
I'll say it again: until you instrument your cooling intakes and outlets with pressure sensors to measure pressure recovery and pressure drop, you're working in the blind with regards to getting better cooling. These MPX5010DP sensors are like $10 a piece, just instrument the shit out of it. See www.n91cz.net/Pressure/PlenumPressure.pdf
The VASI bars don't take into account the flat approach of the canard configuration . I guess you would have the opposite issue approaching in a Wilga.
I know it might seem counterintuitive the electric fans really do restrict airflow in a big way. I saw your footage of the airflow with telltales getting pulled straight back out of the cowling by the prop at idle. In my opinion and with my experience no way are the electric fans pushing that much air. You should try to remove the electric fans for a test. I have a 500HP turbo engine and no matter the electric configuration they just could not push or pull enough air with a radiator and turbos intercoolers. I fought like hell to cool a turbo setup with electric fans for months they just couldn't do the job. In my mind and by the advertised CFM of the electric fans I was convinced they could do the job. I know it is a job to dig them out it was in my setup but when I did I felt like an idiot. It might not work in your setup but it did for my project. Good luck you have made a lot of progress I love the craft it looks amazing just sitting on the ground and even better in the air. It's just a suggestion
Maybe the camera is making it look darker than it is, but I'm noticing a lack of lighting on the aircraft given the flying conditions. (Isn't it better to error a little on the safe side?)
That cooling issue is going to be the make or break deal on whether this kit will be commercially viable. Pilot's are not going to be happy only climbing at 50% horsepower and I don't believe that your other canard competitor has that issue. Someone has already mentioned this in the comments, but the issue may be that the pressure inside your engine bay is too high and air can't escape faster than it is being pulled in. This solution is likely to be way out in left field, but is there anyway that you can take advantage of the effect that agitators use? I don't know if the exhaust would be enough to generate the low pressure needed so perhaps you could siphon off some of the ram air to accomplish that goal? I'm trying to think a little more out of the box for this issue. Wish you the best of luck in this endeavor!
I still can't figure out why you're consistently low on the PAPI (I'm perfectly OK with going below it on SHORT FINAL so as to aim for the numbers) and then keep power in during the flare, resulting in long landings every time. If I'm flying a single-engine experimental aircraft you can bet your life I'm flying a high energy approach, but that would include ABOVE the PAPI and slightly fast until short final. My concern is that an engine issue will make it impossible to reach the runway if you have a problem on your typical patterns from base to final or anything longer than short final.
@@myotherusername9224 But his explanation is diametrically opposed to his goal. Per his own words, slowing down is not a problem, so we both agree that a higher speed is good (until short final) but there is NO GOOD REASON to be below the PAPI. Ask your self if you'd rather be above or below the glidepath with an engine failure on a 2-3 mile final?
@@formulaben it's a feature of canard airplanes. It's kind of what killed the beechcraft starship. There are no flaps on most canard airplanes so if you point the nose down you will pick up airspeed and 3 degrees down is faster than 1.3 times the stall speed which is ideal short approach speed for aircraft. In order to accomplish this he has to come in lower. You could come in at a higher airspeed yes but in order to slow down sufficiently to operate on less than 2500 ft runways in this low drag airframe you would have to install airbrakes somewhere which is a little late to do with this aircraft and that's another moving part to consider that will have to run off of a hydraulic system which means less useful load. Or.... you could come in below the PAPI... or not buy a canard aircraft. 🤷♂️
@@generalrendar7290 I agree with your comments except that he's not on a short runway and the power setting on short final is nowhere near idle; he can clearly come in steeper if he wanted to.
Great looking airplane! The top rear-mounted air intake has me confused, does laminar flow ram air into the scoop, or would the airflow try to reverse because of the lower pressure from lift over the top of the fuselage? I did watch some of the older videos but didn't find an answer.
It's ram air. There's not enough AOA induced low pressure to cause negative effects, though having on the underside would likely increase ram air to an extent.
Maybe the scoop *is* in the wrong place. Sonja Englert fixed this same problem, she moved the aft engine cooling intakes on a Cessna 337 from top to bottom.
@@myotherusername9224 Potentially. There's likely several valid reasons why it was designed to be on top as well. The difference in air volume between top and bottom might be enough to fix the cooling, but it's also possible that there's a negligible or even detrimental difference. Keep in mind that several WWII aircraft gained ram air pressure from an intake scoop mounted in the same place, namely the P-39 and P-63, among others. It was equivalent to about 2"MP at cruise speed if I recall. If it was found to be inadequate to produce proper airflow in the P-39, or if it were possible to produce more via side or bottom scoops, they likely would've integrated it into the P-63 during other upgrades as this would've been a very simple modification. Another little tidbit, the open area of that scoop is about the same size as most WWII fighters had for their radiators. It's likely flowing the same volume of air that is necessary to cool an engine three times the size. I suspect the issue lies more in the size of the radiators or the turbo/intercooler setup rather than the amount of airflow they're receiving.
Peter. in order to solve your cooling issue, try to create more vacuum insde your engine bay, try to measure it. You can try to close upper openable scube and see the difference. Very important is to use your exhaust pipe to help you create more vacum inside the cowling. you don't need more coolers but more stream through them. Your intake scoobe is to bi in comparison with outway...just try it
Yes. Configuring the cowling so that exhaust flow sucks air through the cowling. it's called an extractor. I read about it in EAA Experimenter years ago. Also: www.caro-engineering.com/projects Read the bit about Cessna 337 cooling. She fixed it by moving the air inlets to the high pressure area under the engine and the outlets to the top where the low pressure is.
Absolutely - My aircraft’s 350 HP continental (TSIOL 550) has one big (huge) turbo that keeps full sea level power up to FL250 - and beyond. So it can be done and works great in my experience. The serial twin turbo setup Peter is using poses some challenging questions in terms of reliability (if any one turbo or related accessories fails, the system fails) and restart at altitude - a known weak spot of aviation diesels. One must also consider the increased number of pipes, weld points, clamps that can leak or fail, and the sheer weight penalty - guess where the excess weight is located and why this aircraft needs nose ballast...
The static port is not built and utilized to receive impacted air. Your “fencing” utilization. They’re typically mounted on the side of the fuselage to just read “static air pressure”. You’re pitot tube receives the “RAM” air, typically mounted on a wing or front of aircraft to receive air from the relative wind. Ram air (Pitot tube) minus the static air pressure (Static port) translates to airspeed. If you shove air into the static port, you may give yourself a lower or higher airspeed depending if you’re creating a different “static air pressure” by trying to shove it in that tiny hole..
There aren't many spots on an aircraft that have true static pressure, and there will always be variances...just kick the rudder a bit and watch your instrument readings change. Static port fences are utilized to create an area of static pressure over the orifice when the area in question is consistent in pressure throughout the flight envelope but are otherwise not at ambient pressure. It's more of a fine tuning than anything, especially seeing as how there isn't a well established area of static pressure on the fuselage.
@@Skinflaps_Meatslapper Thank you for that insight. Sounded like the “fencing” was to impact the air into the static port. I understand your explanation. Appreciate the explanation
@@scottbrunt2863 Ah, I see where that might be confusing. It's not quite the same as creating a ram air effect, it's more to bring a state of lower than ambient pressure up to ambient. You can theoretically place a static port anywhere on the aircraft, but some places are naturally better than others...and once you've cut a huge hole into the fuselage for it there's incentive not to move it around to another place that might be just as bad. Most aircraft have places that are close enough to static and that's why you don't see fences on them very often. My personal preference with experimental aircraft are pitot tubes that have static ports integrated with them, since all you really have to do is get it pointing in the right direction...the position relative to the pitot tube has already been engineered in and does away with locating a spot on an aircraft that may or may not be static.
Love the vids.. and pardon my lack of aviation knowledge.... but there seems a huge amount of effort having to go into incremental engine system improvements. This seems to be adding system instability with so many variables in play. Is there merit in going back to square one and reassessing whether it would be better exploring a higher performance proven engine package already in use to provide greater performance and overcome the oil temps and seeming power limitations? There are so many other airframe and system refinements you are pursuing ... and there is only so many hours in the day..
@@rustusandroid thanks good observations ... having looked around I can now seen there are many different options being used in say the velocity airframes ... so I see the segment has a lot of innovation and individual solutions being explored. I have gone back to the earlier videos to understand the Engine development program.... nothing but admiration for the dedication and application going into the project . Cheers!
@@tujmeister thanks for the great background ....I have now had a look at the various developments in the segment ... with LS, rotary and others in say the velocity craft and can see that Peter is exploring a significant ‘step change’ in dynamics. I have also gone back to the earlier videos to understand the concept and journey ... great determination, application and innovation... will continue to follow Peter’s journey with great interest. Again, thanks for taking the time to provide the context. Cheers
"I'm getting a little bit behind on the videos here because I've been actually getting quite a bit of flying in each evening." If there's ever an excuse that makes me totally fine with late videos...it's this one. You do you bro, I'm more than happy to wait.
Peter, in regards to adding flaperons on the production models, it seems all your approaches are consistantly low. Does your seat position, and lack of flaps prevent you from seeing well on a 3 degree glideslope without the nose lowering effect of flaps/flaperon. Not meant to be a dig, just wondering if there's a genuine reason for it.
This is an issue with all canard aircraft. The Long EZ deals with this by having an extendable airbrake. However the Rutan inspired Velocity aircraft usually don't have this because the forces would be too great to overcome with a light hand crank so that decreases useful load significantly if one is installed, so they come in low. The Beechcraft Starship had a moveable canard but that killed it's commercial viability. Flaps allow you to descend at a greater angle of attack while picking up less airspeed while a canard design relies on the canard having a higher angle of incidence than the main wing in order to maintain controllability and prevent a main wing stall. Flaps raise the angle of incidence of the wing and this could make stall recovery next to impossible if the main wing stalls before the canard. The strength of the canard design relies on the resistance to the main wing stall by guaranteeing that the canard stalls first and pitches in the correct direction for a stall recovery. So in order to keep useful load high, use less moving parts, and not having to remember to retract the airbrake in a go around, canard pilots come in on a flatter approach. Reward vs. Risk.
It seems at lower altitude at least, the cooling scoop will need to always be fully extended...... any thought into either making the scoop extend a little more.... or putting an electric fan on the 2nd radiator, or on the exit to the cowling to increase mass flow?
The problem is he's trying to get air to enter the cowl at a region of lower pressure and exit to an area of higher pressure. www.caro-engineering.com/projects Read the bit about Cessna 337 cooling. She fixed it by moving the air inlets to the high pressure area under the engine and the outlets to the top where the low pressure is. The other thing he needs to do is position the exhaust system outlet just inside the cowling so as the gases leave they entrain the hot air and pull it out. It's kind of like the opposite or inverse if the Coanda effect; instead of following a contour, the flowing exhaust gases force the gas next to them to conform to their flow.
I don't quite understand. Why don't you put a big oil cooler at the front of the ram scoop? Then have a medium scoop at the nose? Maybe a small intake around the engine housing too?
For what it is worth, I am fan of your project and have been following it closely for quite a a while. Right now the cooling issue is your number one challenge to solve? It seems worthwhile to pick a goal (Run the AC on a hot day and be able to get full power on the climb for some duration of time) and then do what is necessary from a cooling/engineering perspective to hit that goal. Anything else would seem to be meandering and wandering half measures? Perhaps I am wrong in this, but from time to time you have to pull your head out of the weeds and redefine a top line goal based on your most recent accomplishments? Again.. am a huge fan and offer this point of view for consideration. Fully expect whatever path you pick you will get it sorted and working. Great work Peter.
Cooling is a trade-off. If you size the system to withstand durably full power and full AC in the climb condition on a hot day, your aircraft will look like a manta ray and you’ll end up with a huge penalty in cruise. The dark art of successful cooling is very complex and requires many experiments because no simulation is accurate enough...
Is the radiator a 1 core and possibly put in a 3 core radiator? I'm sure it's a dumb question. Your videos are great. Keep them coming. We all need positive entertainment which is very rare. Thanks.
Hello Peter, thank you for the update. Don’t let the negative comments get you down. I think you are doing an amazing job, I have been following you since day one and you haven’t let me down once, and I will be here for the long haul. Thank you Wiz
Would it be possible to dissipate heat from any of exterior structural surfaces ? I guess dumping some heat in the wing tanks might be possibility at least as long as they are not empty
The problem is trying to get air to enter the cowl at a region of lower pressure and exit to an area of higher pressure. Fighting the pressure gradient instead of taking advantage of it. www.caro-engineering.com/projects Read the bit about Cessna 337 cooling. She fixed it by moving the air inlets to the high pressure area under the engine and the outlets to the top where the low pressure is. The other thing to do is position the exhaust system outlet just inside the cowling so as the gases leave they entrain the hot air and pull it out. It's kind of like the opposite or inverse of the Coanda effect; instead of following a contour, the flowing exhaust gases force the gas next to them to conform to their flow. It's called an extractor system, I saw it in the EAA magazine years ago.
Peter what is the water temp leaving the turbos then ? If the turbo pyros are producing 1400 degrees constantly then the oil has to be crazy hot, in heavy Diesel engines we try to not exceed sustained temps over 1000 degrees, we need to look at how farm tractors shake of there turbo and water temps because they are very similar in that they are staying in there max workload for a sustained period .
Have you considered putting the oil cooler outside the skin (under a cowl) with a door to regulate flow - rather than trying to get full flow through the engine cover? Keep up the great work!
You want to get rid of those vorticee you are going to want some tip tank shaped apparatuses with x shaped winglets. Basically mini rockets. Which would also be the perfect place for your static port. Flights are looking great.
I can't imagine what was on those AN fittings, that would make them leak on a slightly inconvenient reassembly ? The 37 degree taper cures all usually . Was there some accumulated oil on the threaded area, that came out later ?
@@zmanmd1641 ,,, no, not in the short term . I think Peter was being toooo scrupulous, and just saw some oil that had been trapped above the taper locks .
Would like to put in a request for some wide shots of a Takeoff and a Landing. Thanks for your transparency and commitment to the success of the Raptor. I’m sure that after building this bird from scratch that Peter is well aware of where he wants to focus on the improvements to the design. Some of these Negative Nancy comments are exhausting. Keep the Faith Peter 👍✈️
Very nice Peter...The evening sky is beautiful... Curious if you can use the air conditioning loop for auxiliary oil cooling? Just switch the refrigerant flow from the evaporator coil to a tube in tube heat exchange coil?
@@grandenauto3214 I totally agree...My thinking is that the air conditioning system is only used while on the ground...Why not try to leverage something that is already onboard instead of adding more weight...But I agree, always prefer real solutions over bandaids...It’s just fun to brainstorm ideas...
glad to see stability in take off and landings. hope the oil cooler works out well. Happy to see progress and air time!!! keep it up!!!1,000,000 attabits!!!
Peter, Good show! I don't know how you have found the time to video document all that you have over the years. My new years plan was to do more video of projects I'm spending time with however I'm just too busy. I admire that you can. When I regularly work with aircraft, evening and night flights are the primary times I fly. I'm taking off after most had landed. Thanks for all your presentations. Raptor just keeps getting better and better thanks to your perseverance and problem solving capabilities. Cheers
