Raptor Composite Aircraft

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cheapracer

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With an electronically controlled injection, FBW is the only option.
All EFi cars had cable throttle control before FBW became the norm through the 1990s to early 2000s. I got engines sitting in my factory right now that are EFi and cable.

For whoever asked, diesel throttle control, cable or FBW, goes direct to the injection system, and monitors how much fuel is allowed. Diesels have no throttle valve in the induction system (some have had an engine brake throttle valve).

Raptor guy needs a helmet, he's travelling at 100+ mph on each of those runs.

The front wheel shimmy may be due to all these runs close together over the recent weeks, getting the wheel bearings hot and loosening, they may need to be inspected and adjusted.

100 mph and 3200lbs on wheelbarrow wheels has always made me shudder.

Also the throttle and elevator trim issue are clearly Wasabi's fault, because I like to bandwagon 😁
 

FTEstudent

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If the nose comes up at the airspeeds he is running then he will have his hands full. In my view what he is doing is really risky. As I say, I hope he doesn't get hurt.
Yeah his aerodynamic analysis is basically zero. He literally said he's gonna add more trim (cuz the air pressure pushed it back) and hope that works, like really? It's sad that his youtube audience thinks that thing is the really gonna fly....why I came over here to talk to sane people.
 

aeromomentum

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As someone that has flown coast to coast, border to border and New Hampshire to Key West more than a few times I would love a roomy, comfortable, fast and economical aircraft. I have no problem with two 4+ hour legs in a day. I would much prefer one 6 hour non stop 1500 mile flight getting 20+mpg. For most trips this will beat the airlines in terms of time. It could even beat the cost for 4 people.
 

TFF

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Most pilots want to get going. It’s the passengers that can’t take it unless it’s a family thing.

I know someone who can easily put in 10 hour flying days. 10 in the air. I have seen him do more in an emergency. It’s where he wants to be.

A SR22 will do five hours. I have done it. That’s using every drop. If you are ready, it’s no big deal. Occasional passengers aren’t. A friend was flying a Cirrus with the owners. Flying family. Dad had just stopped flying this plane and needed someone to fly it and sons were busy. Mom needed to pee, crawled into the baggage and went in one of the absorbent bags. She had undone her headset and they asked her a question with no response. Her husband turned around and she is not there. My friend turns around and says, dam the Rapture has come and I’m stuck here with you. You have to have family ready at stay in the air and know the drill. My friend already figured it out from the trim change.
The question is not you flying for five hours, it’s about the passengers flying for five.
 

Mark Z

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I like 2.5 hour legs to break it up unless I’m getting a stellar tailwind. The 210 is a good ride; last year we made it back in an easy day from upstate NY to the DFW area in 8 hours on the tach with 2 fuel stops. It will be a better airplane when the FAA passes me into the “Non-commercial” type.
 

rbarnes

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Frankly my butt wont take more than 3.5 hrs in a plane seat. I'm fine with stopping for gas every 3.5 hours if flying 1,000+ miles. I'm not peeing in a bag or down a tube. Sorry I will never be in that big a hurry.
The DA42 and DA62 come real close to meeting the 20mpg and 1,000+ mile range in comfort criteria. I just lost that spare $1.5 mil under the couch again.
Another thing that alway made me dream of having Pilatus if I become a billionaire somehow. Enclosed stand up bathroom in basically a pressurized super fast Otter.
 

wsimpso1

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So nobody checked for springy elevator?
How does the trim work? (trim tab? spring on elevator?)
Given that Wasabi Flight Test caught and was really concerned about the springy aileron circuit, I would expect that they also checked the elevator and rudder circuits. That would be a HUGE miss if they did not catch that.

Also, PM did take the test article to speed sufficient that when he pulled power with one hand and pulled back on the elevator with the other, the whole thing lifted off very briefly, then plopped back on... So it looks like it can get the nose up once it is fast enough.

I do believe that the elevator has springs based upon Justin's comments on the spring dominating elevator feel during his taxi runs.

We are mostly used to airplanes with the mains only slightly aft of CG and a tail in the prop wash so it can have some extra authority during takeoff. If you have the mains aft of the balance point, and the nose wheel is just barely unloaded, weight on the mains makes a strong nose down pitching moment. To lift the nose wheel, the total airplane pitching moment must be slightly greater than the moment from the weight on those mains. Until you get nearly to speeds where the elevator can do that, there will not be much effect from playing with the elevator. On top of that, all of the landing gear appears to have pretty high spring rates, which will make for small attitude changes when you play with the controls until you get to flight speeds. There are ships that do this already in the inventory. Many canards , some twins, some jetliners, and a number of tractor prop T-tails require getting above a certain airspeed, a hefty pull to rotate, then backing off the stick to hold climb attitude. Not ideal, but hardly the end of the world.

Billski
 

cheapracer

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Given that Wasabi Flight Test caught and was really concerned about the springy aileron circuit, I would expect that they also checked the elevator and rudder circuits.
That would be a HUGE miss if they did not catch that.
Wasabi didn't get to the higher taxi speeds, or use the trim to have that issue raise it's head.

Only raptor guy has been to the higher speeds that demonstrate air pressure on the elevator overcomes the trim spring pressure.

Credit where credit is due, was well spotted by him, of course offset by his sillyness of: I'll just use more trim ~ and when it starts to lift, and he slows down, the trim will automatically increase and try to keep lifting the nose for a bit, or hold status quo. He doesn't think these things out.
 

lelievre12

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Ahhh. Diesel... No throttle butterfly... Forgot about that part.
Actually most auto Diesels have a butterfly mainly to get a positive engine cut when ignition is switched off. You might have seen YouTube videos of "Diesel runaway" which is where the Diesel will keep running (sometimes at full power) if an oil leak (such as a turbo seal or EGR failure) injects engine oil into the inlet. This happens quite a lot and so to avoid getting sued, car makers put in the throttle.

Racers (and plane builders) usually take the throttle off as its not needed for normal Diesel operation however I am unsure whether PM has it on or not. If he did indeed remove it (the engine is like really light right?) then if one of those nice Raptor turbo's blows a seal you will get biblical amounts of smoke and uncontrolled full power until the engine seizes. That might provide some real adventure on the next YouTube installment of 'Days of our Lives', or sorry; "Ways she no Flies". :)
 

Marc Zeitlin

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Marc Zeitlin can correct me, but I didn't think any canards flew themselves off the runway.
Generally, that's true - the plans ground incidence angles tend to require an "up" elevator input (TE down) to raise the canard and get the wing to the correct AOA for rotation. HOWEVER, I have flown a couple of canards (COZY MKIV's) on which the wing incidence angle was set a couple of degrees too high, and as soon as I started pulling aft on the stick and causing TE down elevator deflection, the plane basically levitated off the runway. A little weird, but can be done. Usually it's not, because then the fuselage is at the wrong AOA during cruise flight for minimum drag (at least theoretically).
 

Marc Zeitlin

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So nobody checked for springy elevator?
Keep up, Bill :). Yes, we checked the elevator system numerous times, and the trim system has been discussed here numerous times. There is very little play or compliance between the stick and the elevator motion. All the motion you see in the latest video is the trim system reaction to the aero loads. Since the hinge line of the elevators is so low and far forward, any aero loads create a HUGE hinge moment that the trim system needs to work against.

How does the trim work? (trim tab? spring on elevator?)
Peter had originally used a coil compression spring in an inappropriate manner for elevator trim, and it basically either did nothing or worse, had a negative feedback effect depending upon elevator and trim motor position. One of my "fix this" issues was "implement a trim system similar to the Velocity system", and he kind of did, with metal cantilever springs and the original electric actuator. At least it currently has a monotonically increasing force opposing the aero forces.

I've got one COZY MKIV that I maintain and fly at times for a customer that for reasons that aren't very well understood, although completely controllable and flyable, the trim system as implemented gives the plane SLIGHT negative speed stability. Strange, but not worth fixing. Probably a combination of poor elevator contouring and very low trim system stiffness.
 

BoKu

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...It's sad that his youtube audience thinks that thing is the really gonna fly....why I came over here to talk to sane people.
I'm actually pretty confident that it will fly, and be reasonably controllable. However, I think it will have a relatively narrow operational envelope, won't come close to the claimed performance, and will suffer frequent propulsion issues including but not limited to complete power failures.
 

poormansairforce

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I don't wish harm on anyone especially those not responsible so after thinking about it for a while I've come to realize that the Raptor has the perfect test pilot! We are all responsible for our choices.
 
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SuperSpinach

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Does Peter use full power on every high speed taxi ? Seeing all those comments on the redrive that say that it won"t hold, I'm surprised there hasn't been more issues with it. I feel like problems would have appeared by now if he used full throttle every time.
Does anyone know ?
 
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