Thoughts on Velocity aircraft

[carusoam]

The Raptor site gives you some insight to how complex every detail is going into each decision...

If Art an Al had some cad cam equipment back in the late 50s, they would have some nice fancy drawings to go with the plane they built....

http://www.raptor-aircraft.com/

Best regards,

-a-

Edited April 9, 2017 by carusoam

[buddy]

I put my 2K in escrow, number 1035. 

[mike_elliott]

Just now, buddy said:

I put my 2K in escrow, number 1035. 

#155

[jaylw314]

Nobody has mentioned the Rutan Defiant (4 seat twin-engine).  Of course, Wikipedia suggests there are only 19 registered in the US so it might be hard to find one...

https://en.wikipedia.org/wiki/Rutan_Defiant

Edited September 26, 2017 by jaylw314

[steingar]

One of the guys on my old field had one he'd had someone build for him.  My guess is the arrangement was illegal, but I wasn't going to drop a dime.  I saw him once cutting holes in the airframe.  Thing cost him close to a half million and he was cutting holes in it.  Joy of experimentals, he said.  He was putting in extra air scoops because he was having cooling issues.  The funny thing is the scoops weren't aerodynamic anything.  He just modeled them off the nose of the airframe.  Last I saw the cooling issues were tamed, but all the extra airflow was forcing the cowing flaps open.

If I'm not mistaken those things don't have any landing flaps, so you come in pretty fast.  Say goodbye to short strips.  And energy increases with the square of the velocity, meaning you get to dissipate four times the energy if you crash that Velocity than if you crash your Mooney.  Oh, and that Mooney has a steel roll cage to absorb the energy.

Of course, Cozy's are mostly four place aircraft, though I don't know how fast they go.  Cheaper than Velocity's most days.

As much as I like flying, the OP's mission sounds like one for an airliner to me, though.  Those kind of trips in a piston single or even twin sound like adventures.

[jetdriven]

There is a huge thread Over on BT but the Raptor is fantasy. You might get 200kts you might get 7 GPh but not anywhere near both. 

[mike_elliott]

1 minute ago, jetdriven said:

There is a huge thread Over on BT but the Raptor is fantasy. You might get 200kts you might get 7 GPh but not anywhere near both. 

Wow, a huge thread must mean Peter shouldn't bother going forward.

[jetdriven]

He should give up on the wild claims and level with the people he is taking money from 

IT takes 300 Hp to push anything else through the sky at 200kts and this plane is not only bigger but 50-100kt faster and has a fantasy 300HP Audi diesel that somehow gets twice the BSFC of any other diesel on the planet including ocean going ships. And not to mention that diesels still aren't coming around for aircraft to begin with, despite Henry Ford's prediction.  Anyway,  Math wins every time and I can't even begin to  see that project coming to life. But that's just skeptical me, but the promises they claim are completely Made up. 

Edited September 27, 2017 by jetdriven

[Guest]

Another flash in the pan.  How many will loose their shirts on this scheme?

Clarence

[bradp]

No plans to put a deposit down on the Raptor - but it's nice seeing the video blog of the thing coming together.  It's cool seeing the thing being built piece by piece.

There's an open house on October 21'st in GA. 

[mccdeuce]

I am not as skeptical as others.  I do have a deposit down if nothing more than the intrigue of it all.  

I also am building a Glasair - the first pre-molded composite kit aircraft. (although mine is a super 2 so a few thousand kits down the line).  It was manufactured about the time I was born.  No computers.  No CNC. Nothing fits well together.  Some of the first advice I was given when I started to build was buy a dremel.  Then go and buy 2 more, cause you are going to spend quite a bit of time getting the "pre-molded" pieces to fit together.  

So I am intrigued at the precision at which the Raptor team is building their prototype and the molds for construction.  Do I think they are padding their numbers - yes.  Just like Mooney did. 

I routinely get my 201 mph airplane to top out at 180 mph...

 

Audi engine -  not my first choice.  but in no way would it be a Lyco or Cont.  (other threads I talk about my project of converting a rotary) and we will see if I go through with the purchase based mostly on whether or not the Raptor team is on board with being part of the experimental market.  Vans is not.  Put the engine we tell you to put up front.  Oh and buy through us so we get the commission.   (Maybe we can see where my pessimism and skeptical nature lies). 

In the end though - I applaud the Raptor team for giving something different a shot. It won't be for everyone though. 

 

[mccdeuce]

On 4/9/2017 at 4:09 PM, peevee said:

Auto engines never work well in airplanes. Eggenfelner, rotary, i haven't see a builder happy with the performance and in the RV world you see those guys selling them and going Lycoming. Asking an auto engine to run at 100 percent power for 20 minutes and 75 percent for several hours isn't really what they're designed for.

Thats not entirely accurate - there are quite a few rotary engines powering plenty of aircraft out there.  Is is the same number no not at all.  But it requires a ton more work.  Most people reach there exhaustion point in the construction and don't want to tinker or work the engine.  And that is the number one reason the alternative engines get repurposed. 

The largest issue most of these engines have is cooling. Once you get the cooling worked they can be very reliable.  Problem is that every installation is one off so getting it to work is the challenge.  But that is truly the nature of Experimental and why I take issue with Vans RV.  They don't want you to experiment, in fact it has been my experience that they discourage it.  All for saying "hey we designed this around X engine" but progress requires tinkering.  

The other thing that often gets misled is cost.  For initial cost I could put a used Lyco upfront for about the cost of putting in my rotary. For me its about the reliability, cost to overhaul, operating cost, smoothness and performance.  

[carusoam]

How does one get a feel for what flying a Raptor is like? I came close to flying in a Long EZ.  But, Putting two men in the plane didn't seem to match the WnB requirement...

 

They have committed to Garmin instruments and MT for the propellor... Reading deeply into the website you find a mention of the 3L Audi TDI.

 

Should be a few of those available... (good news)

https://www.audiusa.com/about/diesel-information

I would expect the leading edge of the MT prop is going to show some erosion, depending on what runway you actually use.  Pusher props tend to get stones thrown at them...

I'm more of a fan of 300hp of the TN'd IO550

So expensive for experimenting...

Best regards,

-a-

 

[DaV8or]

3 hours ago, jetdriven said:

 Anyway,  Math wins every time and I can't even begin to  see that project coming to life. But that's just skeptical me, but the promises they claim are completely Made up. 

Absolutely agreed. These performance numbers were only made up to draw in deposits from hopeful people that something new from somebody somewhere will revitalize GA and finally provide the solution to the dream of a safe, affordable personal airliner.

It's no accident they chose a canard design. It looks like "the future" and "out of the box cutting edge" design.  

A Velocity with a car engine in it. What's new about this plane? I'm pretty sure a homebuilder out there somewhere has already done it. Someone might be able to seek that plane out and see how she flies.

[jkhirsch]

The deposits are held in escrow and refundable.

[aviatoreb]

18 hours ago, jetdriven said:

 Anyway,  Math wins every time ...

yay Math!

[aviatoreb]

On 3/30/2017 at 10:39 PM, gsxrpilot said:

I think you can get 185kts ROP at 14gph in the 252 at 12K.

That is interesting - how much horse power is 14gph on that engine?

I say interesting because that is pretty close to the rocket on 15gph, at 55% power, and I would expect a little bit less efficiency given we drag around bigger cylinders.  But otherwise similar airframe. (Note mine is 5+kts slower on the burn rate-speed than that and I blame the tks).

[aviatoreb]

Twinkie's make me nervous.  Sure they are efficient as twins for the cruise speed because they have those little IO320's, and sure if I were flying over rocks at night I would want that second engine just in case.  But they make me very nervous for the failure on take off scenario, especially if fully loaded since I wonder if there is any climb with a single little engine.  I know I know its supposed to be tested but in a twin I would think excess power on each engine is a must because of the engine out on take off scenario and twinkie is the opposite of excess power even with one concept - because they were shooting for efficiency.  I have 4.4 hrs of twinie time in my logbook.  So I am no expert but I have been in them anyway to have thought about it.

[Jerry 5TJ]

Twinkie one engine out rate of climb required: None.

Here is the required performance under which the Twin Comanche was certified:

6,000 pounds or less maximum weight and VSO 61 knots or less: the single-engine rate of climb at 5,000 feet MSL must simply be determined. The rate of climb could be a negative number. There is no requirement for a single-engine positive rate of climb at 5,000 feet or any other altitude. For light-twins type certificated February 4, 1991, or thereafter, the single-engine climb gradient (positive or negative) is simply determined. 

 

Ref: FAA Policy

 

[aviatoreb]

32 minutes ago, Jerry 5TJ said:

Twinkie one engine out rate of climb required: None.

Here is the required performance under which the Twin Comanche was certified:

6,000 pounds or less maximum weight and VSO 61 knots or less: the single-engine rate of climb at 5,000 feet MSL must simply be determined. The rate of climb could be a negative number. There is no requirement for a single-engine positive rate of climb at 5,000 feet or any other altitude. For light-twins type certificated February 4, 1991, or thereafter, the single-engine climb gradient (positive or negative) is simply determined. 

 

Ref: FAA Policy

 

Oh goodie.

I figure if I were owning a twin - I would want to know the loaded weight I could carry and still climb out at 500fpm and then i would want to use that as my own personal max loading.  So that this would be greater than my own body mass, I figure many light twins would require a pair of big bores.

Between this part, and the fact that many twins are driven by owners who are not sufficiently current to handle the quick emergency handling (feather) for an engine out upon take off - I figure that most twins in most owners hands are worse than a single in most owners hands. Not to revive ye ol' debate.

[steingar]

One of my pals lost an engine on takeoff in his Aztec, wound up on a city street.  Walked away, but one less Aztec.  I suppose the failure happened when the thing was too slow.  Disclaimer, I've never flown a twin anything.  Flew a Ford Trimotor once, though.

[aviatoreb]

This is my idea of a multi-engine airplane that I could handle an engine out (or two) in:

 

[bradp]

The one piece of engineering I really don’t like so far with the raptor is the design of the front baggage compartment.  It seems to be hinged near the windscreen.  Door pops and either the windscreen view is blocked or the door flies up and over into the prop.  Either putting the hinge on the tip of the nose or putting two side doors like a bonanza cowling would fix this.  Hope I’m wrong.   

[Shiny moose]

The difference in a 200kt vs a 185kt airplane flying from BOS to LAX 2270 miles in a no wind ( hahaha) flight is only an hour, downgrading to 150kts will add another 3 hours or 15 total flying hours. remember I said no wind!!! no matter how you look at this its a long ass couple of days travel. If you have a couple of young kids and a wife asking them to remain calm and sitting for 2 full flying days adding in fuel and food stops, you will only do this trip a few times before it ends, either by the boss( your wife) or by you not wanting to hear the boss tell you she doesn't want to do this anymore.

My opinion only!

 

 

 

 

Sent from my iPad using Tapatalk

 

[Guitarmaster]

On 9/26/2017 at 9:20 PM, mccdeuce said:

Audi engine -  not my first choice.  but in no way would it be a Lyco or Cont.  (other threads I talk about my project of converting a rotary) and we will see if I go through with the purchase based mostly on whether or not the Raptor team is on board with being part of the experimental market.  Vans is not.  Put the engine we tell you to put up front.  Oh and buy through us so we get the commission.   (Maybe we can see where my pessimism and skeptical nature lies). 

In the end though - I applaud the Raptor team for giving something different a shot. It won't be for everyone though.

I am number 540.  If I had deposited when I first heard of him, I would be about number 20.  I wanted to see a number of copies flying before I put my family in one.  

Regarding the engine choice:
Personally, I'm happy with the engine choice.  The 3.0 is a time-tested, strong and reliable engine.  I think it would have been a mistake to power it with a 'traditional' engine.  After all, this really is the essence of experimental.  It's not for everyone. I don't view Van's Aircraft as experimental, simply a kit.  Much like legos. 
Simply saying it takes 300HP to go a certain speed takes alot out of the equation.  Namely, torque.  A diesel, by nature, is much higher torque at lowers RPM due to the higher compression ratio. In this case, 16.9:1  
The direct-drive engine obviously only gives you torque to the prop that is available from the crank and is reliant on RPM.   An IO-540 turns out roughly 500lbft at the crank.  Full disclosure, I can't find any published torque numbers, but using the 'power formula,' that is roughly the number at 2700 RPM.  
The Raptor is using a belt-reduction drive which I believe is somewhere around 1.5:1 (I don't remember exactly).  The stock Audi numbers are 240HP and 428lbft,  If you "gear down," the HP doesn't change, but the delivered torque does.  Even without tuning (which they are doing) the delivered torque to the prop should be around 642lbft.  Of course, this is not accounting for any mechanical loss. Rough calculations prop RPM will be 2200 and engine RPM 3400.  This is well below the 5250RPM redline.
Bringing up the horsepower through tuning will boost the torque dramatically.  I do this in my diesel truck.  Stock tune is 397 and 780.  A very mild tune puts it at 490/950.  Again, the spirit of experimentation. With the above compression ratio, there is LOTS of 'head-room' to increase boost and fueling.
I've been tuning for a long time.  A 50-100 hp tune is very safe and affects longevity very little; at least with the engine.  Other parts... well.... Big torque means turning a big prop with lots of pitch in cruise.  Something a direct-drive engine won't do without significant HP reduction.

I've been doing diesel for a long time.  With limp mode deactivated, I would happily fly behind my 6.6 Duramax.  

In the end, I am looking at this as I may be out $2000 or I may end up with a 'most excellent' airplane.  Risk vs. reward is miniscule.

Edited September 30, 2017 by Guitarmaster