DreamWings "Valkyrie"
Marv Hamm
Scott Christensen wrote:
Anybody see this "dreamwings" at OSH?
Whatcha think?
***************************************************
Scott,
Latest pictures of DreamWings "Valkyrie" (back from Oshkosh) :
Kit--Tandem 2 seat--Canard--Pusher--Bubble canopy--twin tail boom
--carbon composite---should fly about end of August. Kit deliveries
should start about end of year. I have ordered one : )
http://www.dreamwings.com/pics_htm/pics29.htm
I have been following them since early this year. Went up to see them in
Lawrence, Kansas (their factory--at the municipal airport); Sun-n-Fun;
& Oshkosh. It looks great ! Not real fast, but should be great fun to
fly---high lift wing with low stall speed and great climb performance.
Beautiful plane---Great visibility and room from both front and rear seats.
STOL performance with a good engine, aerobatic, "trailerable", plans for
a float kit, & more. They are trying to make it available as a legal
ultralight
as well as 51% registered homebuilt. Planned engines range from
28 hp to 125 hp. First one tested will be with the Jabiru 80 hp. I believe
that
most buyers will be choosing the 51% registered homebuilt kit version
(same price) for the option of using the more powerful engines.
Marv Hamm
MRS
IMO the project looks like vapor ware.
I dont think I would put a deposit on one until flight and structural
testing is complete.
When will the prototype fly? The latest from OSH indicated within 6 weeks
the airshow. Does any one truly believe this will happen?
Mike S
Marv Hamm wrote in message ...
MRS
MRS
Marc McNaughton
Mitty" factor down, as they mention in their website.
Marv, I sincerely hope this works out for you. Unfortunately, their site has
all the earmarks of a company that is a little too busy dreaming and not
quite busy enough thinking. Don't get me wrong, the fact that they've got
hardware going together puts them far above most of the companies in this
category! Some of the warning signs:
1. Multiple designs - all being developed simultaneously. Granted, it
appears that they're putting most of the effort into the Valkyrie. That's a
plus. One project is enough of a hassle for a startup company!
2. Taking orders (and deposits) before any of the designs have even flown. I
notice that even though the Hooligan designs appear to have little or no
prototype work done, they're still taking deposits for them. Scary. What
happens if they have development troubles? These are new, unconventional
designs. Problems of some sort are likely, even if they're small ones.
3. Follow-on projects already in the works. I saw drawings for all three
designs with floats, with a legend indicating that the float kits were under
development. I'd really rather see them focus on one project at a time!
4. Lots of splash for such an early stage of development. They're going
awfully public for a company that's never flown a single one of their
designs. Near as I can tell, neither of the principals have any experience
running an aerospace company. That's not necessarily bad, but it's not good
either.
That said, let's look at the airplane itself.
Nice looking, to be sure! But I've got some questions.
1. Empty weight. Now let me tell you, 270# is AWFULLY light for a two
seater! Especially one with a pod-and-boom design, big blown canopy,
separate upholstered seats and that claims to be designed to FAR Part 23
Aerobatic load factors! I know they're using vacuum-bagged carbon and
honeycomb, but still! Something fishy here.
2. That skinny canard. Now don't get me wrong, I LIKE canards! But here
we're talking about using one with a very short chord (from the specs on the
site I get 10.5" mean chord) at a very low "stall" speed. The site lists
31mph for the two-seater. The formula I have for Reynold's number puts the
Rn value under those conditions at 247,500 or so. There's model airplanes
that fly at higher Rn numbers! They list the canard airfoil as a NACA
63615a. Check in your handy Theory of Wing Sections and you'll see that the
Clmax of that airfoil drops off fairly fast with decreasing Rn values. Not
as fast as some of the other 63-series sections, but still. The lowest value
the section has been tested at is 3 million! I can't see that little canard
generating that much lift at such a low speed, due to these Rn problems.
That means it's either gonna feel really nose-heavy at slow speeds (and may
even override the available nose-up trim from the elevator - bad news!!), or
the stall safety might go out the window at higher speeds. Also, the section
seems sensitive to roughness in terms of lift coefficient - can you say
pitch trim problems in the rain? There's better sections to be used under
these conditions than this one. I question its use for this design.
3. Seems like the aircraft can accommodate an extremely broad range of
engines and speeds for one single design. Even when they're shortening the
fuselage for the ultralight version, it would seem to me that either the UL
version is over-strength (and therefore too heavy) or the two-seat version
is under-strength (in which case you'll be needing that ballistic
parachute!).
4. Baggage location: From their website's FAQ (under baggage):
"On all airplanes, the main baggage compartment is in the nose, accessible
via a large hatch on top." Canard aircraft don't like big CG ranges. Why put
the main baggage compartment in the WORST possible place for that?
5. Stall safety: From their website's FAQ (under spin resistance):
"Valkyrie is also designed to FAR 23 Aerobatic requirements, and she can
spin."
Excuse me? If the plane can spin, that means that the main wing is stalling.
Having a main wing that stalls is not usually safe in a canard or
three-surface design!! If you recall, the Cozy was having main-wing stall
problems a while ago. Thing wanted to flip over on it's back! They've since
fixed the problem, but if this spin-ability claim for the Valkyrie is scary!
There is a narrow band of configurations for three-surface planes that can
stall the wing and retain stall characteristics similar to standard
wing-tail combos (i.e. - safe), but that would limit the allowed CG range
even more. See Objection #4.
Perhaps they've overcome all of these objections. I'm not saying any of
these things I've mentioned are definite "show stopper" problems, just
things I'd worry about. I'll look forward to seeing the aircraft actually
fly and getting some independent flight reviews about it (remember the
Prescott Pusher?).
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
Marv Hamm <mjh...@home.com> wrote in message
news:pLYq3.28213$WX1.1...@news1.rdc2.tx.home.com...
The Flying Dutchman
I take exception to your Item #4
4. Baggage location: From their website's FAQ (under baggage): "On all airplanes, the main baggage compartment is in the nose, accessible via a large hatch on top." Canard aircraft don't like big CG ranges. Why put the main baggage compartment in the WORST possible place for that?
Not all canard aircraft have small CG ranges. My Falcon XP
is 540 # empty, 1050# gross. Empty CG is 116", Main wing stalls at
118" CG, flight envelope is 86 to 115". Most normal pilot, passenger,
fuel combos come out to 100-105". That's a LOT of leeway!
Dutch
N507AA
Stillwater, OK
pics at http://members.tripod.com/~DutchR/aviation/index.html
JStricker
Marc McNaughton <Xmar...@home.com> wrote in message
> three-surface design!! If you recall, the Cozy was having main-wing stall
> problems a while ago. Thing wanted to flip over on it's back! They've
since
> fixed the problem,
Marc, your logic is sound, but your facts are in error. AFAIK (and I'm sure
Marc Z or one of the other Cozy guys will correct me if I'm wrong) the Cozy
NEVER had any problems with this as long as the CG was kept within limits
and the aircraft built to plans.
What happened was that Nat Puffer determined that there was not a sufficient
margin of error built in (to accommodate Nat's comfort factor) for
variations in aircraft where people didn't necessarily follow the plans
and/or published CG limits. Nat went to great lengths in testing and
decided that by taking off a bit of the canard, and staying with the
original CG limits, there was still a hefty margin for error, even allowing
for the variations in plans-built aircraft.
My recollection is that there has NEVER been a plans built Cozy enter into a
deep main wing stall, before or after the testing and change in canard.
There were some in the Velocity, however, and that too was addressed by the
factory IIRC. JPR probably knows more about this than I do. But it wasn't
a plans built Cozy.
John Stricker
--
"I didn't spend all these years getting to the top of the food chain
just to become a vegetarian"
radiogenese
>My recollection is that there has NEVER been a plans
>built Cozy enter into a deep main wing stall, before or
>after the testing and change in canard.
>
>There were some in the Velocity, however, and that too was
>addressed by the factory IIRC. JPR probably knows more
>about this than I do. But it wasn't a plans built Cozy.
Deep stall and main wing stall are two different problems.
I test flew a Cozy 4 that had the main wing incidence about
2 degrees too high. The faster I went the more lift the
main produced, increasing the pitching moment and
increasing nose up trim. On the bottom end, it was EASY to
stall the main wing and get a violent snap roll. The first
time was UNEXPECTED, after that it was actually kind of
fun.
On the top end, I could have run out of elevator authority
and pitched down, if I hadn't noticed what was going on.
But because the plane wasn't loaded aft CG there was no
danger of a DEEP (stable) stall. Once the incidence was
corrected the plane flew fine (it still does).
AFAIK, you're right, no plans built Cozy has deep stalled.
But it's just a matter of a light pilot flying one solo,
slow, without ballast in the nose. It's not a design
issue, it's an operations issue. Load a Cessna 177 aft GC
and it will deep stall (see Jessica McClure). There's
nothing magical about a canard.
BTW, Mark, overall your analysis is right on the money.
Dreamwings are appropriately named, they're too good to be
true.
RAD
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Marc McNaughton
me straight! :)
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
JStricker <jstr...@odsys.NOSPAM.net> wrote in message
news:FB5C0C3466F75F33.21FCC2D5...@lp.airnews.net...
>
> Marc McNaughton <Xmar...@home.com> wrote in message
>
> > three-surface design!! If you recall, the Cozy was having main-wing
stall
> > problems a while ago. Thing wanted to flip over on it's back! They've
> since
> > fixed the problem,
>
> Marc, your logic is sound, but your facts are in error. AFAIK (and I'm
sure
> Marc Z or one of the other Cozy guys will correct me if I'm wrong) the
Cozy
> NEVER had any problems with this as long as the CG was kept within limits
> and the aircraft built to plans.
>
> What happened was that Nat Puffer determined that there was not a
sufficient
> margin of error built in (to accommodate Nat's comfort factor) for
> variations in aircraft where people didn't necessarily follow the plans
> and/or published CG limits. Nat went to great lengths in testing and
> decided that by taking off a bit of the canard, and staying with the
> original CG limits, there was still a hefty margin for error, even
allowing
> for the variations in plans-built aircraft.
>
> My recollection is that there has NEVER been a plans built Cozy enter into
a
> deep main wing stall, before or after the testing and change in canard.
>
> There were some in the Velocity, however, and that too was addressed by
the
> factory IIRC. JPR probably knows more about this than I do. But it
wasn't
> a plans built Cozy.
>
Marc McNaughton
I think you may have misunderstood my intent. I wasn't trying to say that
canard a/c CG ranges were in any way a deficiency of the class in general,
or that I think canard a/c are bad in some way because of this. They aren't
and I don't! I happen to like canard and three-surface aircraft, myself.
It's just that in most cases, canard and three-surface designs have
aerodynamic reasons that limit their CG range when compared to a
"conventional" configuration that has similar aerodynamic characteristics.
They simply have more constraints on the allowable range. If the designer
properly takes that into account, there's absolutely no problem with this
"quirk" of canard designs. Actually, three-surface designs like the Valkyrie
can have exceptionally broad CG ranges if certain things are done, but this
usually involves rather complex trim systems and very powerful elevators on
the aft tail - things the Valkyrie seems to lack.
Looking at your Falcon on your web site (and a nice looking bird it is, by
the way!), I have no doubt your machine is everything you say it is. Nice
broad wing chord, generous main wing area and a long arm to the canard tail
compared to the wing chord. Everything that would promote good stability and
a good CG range. It's just that a "conventional" design with similar
characteristics would probably have a little more available CG range. Again,
that's NOT a shot at your XP! While you might have more range AVAILABLE with
a conventional config, you don't NEED any more range than the generous
amount you already have! Your designer did a good job of accommodating the
wing/tail choice he or she made.
My objection on the Valkyrie has to do with the fact that the baggage
configuration isn't a very good one for keeping the range as narrow as
possible - a desirable trait in any configuration. You've got a nice, long
arm from the cg out to the canard on your Falcon. The Valkyrie is rather
short-coupled. I'd be willing to bet that the baggage compartment on your XP
is just behind the passenger seat, very close to the CG of the aircraft.
Correct? That's a great place for it if it's the case. Doesn't move the CG
much. The Valkyrie's baggage compartment is way up in the nose, about as far
from the CG as you can get and not be hanging out on the tails! Imagine how
much more the CG would shift on your plane if the baggage went up by the
canard in front of your feet!
See my point? It's not that canards are deficient in any way due to their
characteristically shorter CG range, it's that the designer needs to take
that into account when they lay out their aircraft. The designer of your
Falcon obviously made the CG range as big as possible, then designed the
load positions quite well in order to fit inside that range. It doesn't seem
to me that the designer of the Valkyrie has done quite so good a job. The
planform of that particular plane suggests a fairly narrow CG range and so
putting the baggage 'way out in the nose doesn't seem like a good idea to
me.
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
The Flying Dutchman <dut...@ionet.net> wrote in message
news:37AF72DE...@ionet.net...
> Marc,
>
> I take exception to your Item #4
>
>
> > 4. Baggage location: From their website's FAQ (under baggage):
> > "On all airplanes, the main baggage compartment is in the nose,
accessible
> > via a large hatch on top." Canard aircraft don't like big CG ranges.
Why put
> > the main baggage compartment in the WORST possible place for that?
> >
>
ChuckSlusarczyk
Marc
If I didn't know better I would swear you were in the conversation I had
with Barnaby Wainfan . Everything you said was brought up in our discussion.
The light weights and stall speeds were my tip offs ,they were Barnabys too but
he looked further into the airfoil and canard size and wasn't impressed.It
would certainly seem that they got the PR down and the Razzle Dazzle but lets
see if there is any substance to the claims. They have a ways to go .I remember
the Prescott Pusher and BD....See ya
Chuck S
Charles K. Scott
radiogenese <anon...@web.remarq.com> writes:
> Load a Cessna 177 aft GC
> and it will deep stall (see Jessica McClure). There's
> nothing magical about a canard.
Not sure you can characterize what happened to that airplane a "deep
stall". That was a stall spin incident. The airplane was observed to
bank to vertical or beyond and half spin to the ground.
Loading a standard configuration airplane aft of CG produces
dangerously light stick forces and even reversal of stick forces. My
impression regarding canard aircraft is that deep stall and main wing
stall are one and the same. If the main wing stalls, there is no way
to recover as the canard will not have the authority to pitch the nose
down at that point. That is exactly why the canard is designed to
stall first which drops the nose preventing the main wing from
stalling. Don't understand how you could enter into a snap roll with
that airplane. Guess there's lots still to learn.
Corky Scott
The Flying Dutchman
I agreed with your entire email, and only took exception the the catch all
phrase "canards have limited CG ranges". My point was not ALL canards do. My
example was my XP which as 29" of range on a 1050 pound airplane. Unless you
flew from the back seat, which is prohibited, you can't screw it up. (BTW, I
don't have a baggage compartment - that's what the back seat is for: "Sorry
honey, there's nowhere for you to sit") . That is actually MORE CG range than
most "conventional" tail airplanes. You're right, it's all in the design.
I love the "looks" of the Valkyrie. I hope they can make it work, but I agree,
right now the specs are highly suspect. But let's not tell them they Can't do
it. They told Wilbur and Orville that and look what happened.
Dutch
Marc McNaughton wrote:
> --
>
> Marc McNaughton
> Irvine, California
>
> Please remove the "X" at the beginning of my e-mail address if you wish to
> send to me directly. I hate spam!
> The Flying Dutchman <dut...@ionet.net> wrote in message
> news:37AF72DE...@ionet.net...
> > Marc,
> >
> > I take exception to your Item #4
> >
> >
> > > 4. Baggage location: From their website's FAQ (under baggage):
> > > "On all airplanes, the main baggage compartment is in the nose,
> accessible
> > > via a large hatch on top." Canard aircraft don't like big CG ranges.
> Why put
> > > the main baggage compartment in the WORST possible place for that?
> > >
> >
Patrick & Carol Hicks
I just wanted to throw my 2 cents worth in here.
I saw the plane at Oshkosh.
It looks like it is being designed for looks and not aerodynamics. You
spotted the canard which is too small to be effective but it sure does
look good. Same with the boom tail. I owned a Skymaster. The rigging
is way too complex and the boom system is very draggy. If the wanted
the plane to use the superior construction materials the would drop the
boom tail and go with a bigger canard, ala a fast Falcon or Speedwing.
If the wanted a more traditional plane the twin boom would go and a v
tail with drive shaft would do it. I owned a Falcon too. It was a
great flyer.
Both of these are aerodynamically superior and mechanically simpler. My
assumption , after looking at the plane closely, was the thing was
designed to be neat to look at. It did not need to be aerodynamically
enhanced. They think if it will fly they have a product.
I think they are missing the boat. That plane construction system
crossed with a Falcon with a high speed but forgiving wing would be a
great design.
My two cents worth.
Patrick Hicks
Bowling Green, Ohio
JStricker
OK, now I'm curious.
What was the ASI showing when the main wing stalled?
It sounds like there was more wrong than angle of incidence. Like maybe the
two main wings were at different angles of incidence(?) and that caused the
snap roll?
Think about the physics of what you're describing, if the CG is well inside
the envelope. (unless your test flights were exploring the edges of the CG
envelope)
The main wing stalls earlier than expected because of a build problem so the
back of the aircraft drops or settles. This increases the AOA of the canard
to the point IT stalls. The whole time, one would assume, airspeed is
bleeding off, possibly approaching "0". When the canard stalls, the Balance
of the a/c causes it to pitch down and, with enough down pitch, airspeed
begins to increase followed by a recovery and possibly a repeat of the cycle
if the stick is simply held back.
Your snap roll problem is what intrigues me. Seems to me that SOMETHING had
to be out of rig to cause that. I don't doubt it was doing it, just trying
to figure out HOW it was doing it. :-)
Your point is correct though, you avoid the deep stall problems with proper
management of the CG. And while you're probably correct that anything can
theoretically deep stall, I'd think it would be pretty hard to get a
conventional design to do it without entering a stall/spin (possibly
unrecoverable) scenario.
John Stricker
--
"I didn't spend all these years getting to the top of the food chain
just to become a vegetarian"
radiogenese <anon...@web.remarq.com> wrote in message
news:9342567...@www.remarq.com...
> Deep stall and main wing stall are two different problems.
>
> I test flew a Cozy 4 that had the main wing incidence about
> 2 degrees too high. The faster I went the more lift the
> main produced, increasing the pitching moment and
> increasing nose up trim. On the bottom end, it was EASY to
> stall the main wing and get a violent snap roll. The first
> time was UNEXPECTED, after that it was actually kind of
> fun.
>
> On the top end, I could have run out of elevator authority
> and pitched down, if I hadn't noticed what was going on.
>
> But because the plane wasn't loaded aft CG there was no
> danger of a DEEP (stable) stall. Once the incidence was
> corrected the plane flew fine (it still does).
>
> AFAIK, you're right, no plans built Cozy has deep stalled.
> But it's just a matter of a light pilot flying one solo,
> slow, without ballast in the nose. It's not a design
> issue, it's an operations issue. Load a Cessna 177 aft GC
> and it will deep stall (see Jessica McClure). There's
> nothing magical about a canard.
>
Russell Kent
> Well, this is one slick-looking ship. They've certainly got the "Walter
> Mitty" factor down, as they mention in their website.
>
> Marv, I sincerely hope this works out for you. Unfortunately, their site has
> all the earmarks of a company that is a little too busy dreaming and not
> quite busy enough thinking. Don't get me wrong, the fact that they've got
> hardware going together puts them far above most of the companies in this
> category! Some of the warning signs:
>
> 1. Multiple designs - all being developed simultaneously. Granted, it
> appears that they're putting most of the effort into the Valkyrie. That's a
> plus. One project is enough of a hassle for a startup company!
I think they will admit guilt about changing horses in mid-stream. They
originally planned to offer the Hooligan (a lousy name, BTW) first, but the
public was/is more interested in the Valkyrie. They also are struggling to
examine "interesting" combinations (like various engines, the floats, etc.) I
consider myself part of the problem, as I was one of the ones who turned them on
to the Motavia powerplant. Hopefully they'll get past this phase of "creaping
featurism" and stop listening to us. :-)
> 2. Taking orders (and deposits) before any of the designs have even flown. I
> notice that even though the Hooligan designs appear to have little or no
> prototype work done, they're still taking deposits for them. Scary. What
> happens if they have development troubles? These are new, unconventional
> designs. Problems of some sort are likely, even if they're small ones.
It is my understanding (and Marv can perhaps confirm) that all deposits are held
by a third party (a bank in Lawrence) in escrow until the kits are delivered.
This means that the buyer's monies are not being used as development capital,
and are therefore not at risk.
> 3. Follow-on projects already in the works. I saw drawings for all three
> designs with floats, with a legend indicating that the float kits were under
> development. I'd really rather see them focus on one project at a time!
See my response to #1 above.
> 4. Lots of splash for such an early stage of development. They're going
> awfully public for a company that's never flown a single one of their
> designs. Near as I can tell, neither of the principals have any experience
> running an aerospace company. That's not necessarily bad, but it's not good
> either.
The splash may be helpful for securing development capital. I don't know where
that capital is coming from, though. Why is "lots of splash" not a good thing?
> That said, let's look at the airplane itself.
>
> Nice looking, to be sure! But I've got some questions.
>
> 1. Empty weight. Now let me tell you, 270# is AWFULLY light for a two
> seater! Especially one with a pod-and-boom design, big blown canopy,
> separate upholstered seats and that claims to be designed to FAR Part 23
> Aerobatic load factors! I know they're using vacuum-bagged carbon and
> honeycomb, but still! Something fishy here.
I think the 270# weight is the single-seat rigged Valkyrie. Not much weight
saved there, but some. Also it may reflect "weight saving" techniques that
didn't (or haven't yet) panned out. For example, they were going to use a
carbon fiber laminate for the main gear, but have since opted for a more
conventional chromalloy gear. That cost them a few pounds, but it probably
hasn't made its way into the literature.
> 2. That skinny canard. Now don't get me wrong, I LIKE canards! But here
> we're talking about using one with a very short chord (from the specs on the
> site I get 10.5" mean chord) at a very low "stall" speed. The site lists
> 31mph for the two-seater. The formula I have for Reynold's number puts the
> Rn value under those conditions at 247,500 or so. There's model airplanes
> that fly at higher Rn numbers! They list the canard airfoil as a NACA
> 63615a. Check in your handy Theory of Wing Sections and you'll see that the
> Clmax of that airfoil drops off fairly fast with decreasing Rn values. Not
> as fast as some of the other 63-series sections, but still. The lowest value
> the section has been tested at is 3 million! I can't see that little canard
> generating that much lift at such a low speed, due to these Rn problems.
> That means it's either gonna feel really nose-heavy at slow speeds (and may
> even override the available nose-up trim from the elevator - bad news!!), or
> the stall safety might go out the window at higher speeds. Also, the section
> seems sensitive to roughness in terms of lift coefficient - can you say
> pitch trim problems in the rain? There's better sections to be used under
> these conditions than this one. I question its use for this design.
I cannot comment on this (I haven't the aeronautical engineering). I guess
we'll have to wait and see how it flies.
> 3. Seems like the aircraft can accommodate an extremely broad range of
> engines and speeds for one single design. Even when they're shortening the
> fuselage for the ultralight version, it would seem to me that either the UL
> version is over-strength (and therefore too heavy) or the two-seat version
> is under-strength (in which case you'll be needing that ballistic
> parachute!).
>
> 4. Baggage location: From their website's FAQ (under baggage):
> "On all airplanes, the main baggage compartment is in the nose, accessible
> via a large hatch on top." Canard aircraft don't like big CG ranges. Why put
> the main baggage compartment in the WORST possible place for that?
If you've seen the baggage compartment, you'll realize that this is a moot
point. :-)
Unless you're in the habit of carrying small bags of lead shot as baggage, I
don't think it will matter. (The baggage comparment shares space with the
nosewheel strut. It's very small.)
> 5. Stall safety: From their website's FAQ (under spin resistance):
> "Valkyrie is also designed to FAR 23 Aerobatic requirements, and she can
> spin."
> Excuse me? If the plane can spin, that means that the main wing is stalling.
> Having a main wing that stalls is not usually safe in a canard or
> three-surface design!! If you recall, the Cozy was having main-wing stall
> problems a while ago. Thing wanted to flip over on it's back! They've since
> fixed the problem, but if this spin-ability claim for the Valkyrie is scary!
> There is a narrow band of configurations for three-surface planes that can
> stall the wing and retain stall characteristics similar to standard
> wing-tail combos (i.e. - safe), but that would limit the allowed CG range
> even more. See Objection #4.
Ibid. #2 above
> Perhaps they've overcome all of these objections. I'm not saying any of
> these things I've mentioned are definite "show stopper" problems, just
> things I'd worry about. I'll look forward to seeing the aircraft actually
> fly and getting some independent flight reviews about it (remember the
> Prescott Pusher?).
I think we're all waiting with baited breath. Should happen any day now.
Russell Kent
Marv Hamm
"Mike S" wrote: Aircraft is fairly suspect structurally. Performance
values questionable..................... it is much more efficient to have
the
new owner probe the dark corners of the flight and structural envelopes.
-------------------------------
Mike,
From what I have seen to date, the DreamWings team seems to be
devoting the resources to "do it right". They have one of the best
setups in the country available for aeronautical structural testing
through the University of Kansas (Lawrence,Ks.). They have
utilized the services of DARcorporation for aeronautical engineering
analysis, design, and consulting. They have assembled an impressive
team to ensure that the "Valkyrie" and follow on models are successful.
They are about to undergo the structural testing, following up with the
flight testing. They have spent a lot of money to date to get to this
point, and have no intention of shipping out the product early for
"owner testing of the envelope".
It is an ambitious project to attempt to make such a light aircraft
strong enough to qualify as either an ultralight or registerable
homebuilt utilizing more powerful (and heavier) engines. If anyone
can do it, I think that they will.
To be quite honest, I have spent some time with this team and John Hunter,
the corporation's president, and I don't think this project is really about
"money".
(Note: Deposits are refundable and familiarization flights will be
available.)
Marv Hamm................. mjh...@home.net
Links to monitor progress:
Current pictures at: http://www.dreamwings.com/pics_htm/pics29.htm
Homepage: http://www.dreamwings.com
P.S. Last year at Oshkosh, they were planning for the "Hooligan" to be
their first offering......but a large majority of orders (and interest) came
in for the "Valkyrie". That was the reason they switched gears and
developed the Valkyrie first.
Marc McNaughton
horizontal tail (often a T-tail) being blanketed by the wake of the stalled
wing - such that elevator power is severely reduced. In that case, the
airplane can get "stuck" in this condition. Not a ride I'd like to have!
Given that definition, canard aircraft would seem to be mostly excluded from
this specific problem. A three-surface aircraft would not be, of course.
Deep stall this is something that's checked on conventional aircraft designs
as a matter of course, especially if they have a T-tail.
Stalling the main wing on a canard, on the other hand, is an entirely
different animal. If the canard is still "flying" when the wing stalls, the
nose will want to rise rather violently! Eventually the canard itself will
stall, of course, but there may be enough energy developed in that pitch-up
that the inertia of the aircraft itself carries it over onto it's back. An
ugly situation!
It strikes me that if one wing panel lets go (stalls) before the other, an
airplane in this situation would drop a wing as much as or even more
violently than the worst "conventional" airplane, since the canard is still
flying and feeding energy into the system. Betcha it'd FEEL like a snap
roll! :)
Canards and three-surface airplanes are tricky beasts to design. Get it
right and you can get a lot of neat advantages over "conventional"
airplanes. Get it wrong and you've got a REAL handful in the air!
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
JStricker <jstr...@odsys.NOSPAM.net> wrote in message
news:07FD1DEB43A91675.B5B60400...@lp.airnews.net...
Marc McNaughton
suspect that a lot of pilots would like it if they can bring it completely
into reality.
However, I suspect we'll be hearing some facts come out after flight test
that the weight is up, "stall" speed is up and the main baggage is now
either behind the passenger or in the passenger seat just like your XP.
If they were talking about a plane with a say... 600-700# empty weight, a
"stall" speed in the low fifties (mph) and an "empty" nose, I'd have a lot
less reservations about the design itself. Betcha it ends up with specs like
that! :)
BTW, my quick glance at your web site seemed to indicate that your Falcon
was "returning" to flight status. Was this a restoration or have I misread
something? Regardless, a slick looking ship, as I mentioned before! You must
LOVE the view from that cockpit.
--
Marc McNaughton
Primary Color
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
The Flying Dutchman <dut...@ionet.net> wrote in message
news:37B027C7...@ionet.net...
> > --
> >
> > Marc McNaughton
> > Irvine, California
> >
> > Please remove the "X" at the beginning of my e-mail address if you wish
to
> > send to me directly. I hate spam!
> > The Flying Dutchman <dut...@ionet.net> wrote in message
> > news:37AF72DE...@ionet.net...
> > > Marc,
> > >
> > > I take exception to your Item #4
> > >
> > >
> > > > 4. Baggage location: From their website's FAQ (under baggage):
> > > > "On all airplanes, the main baggage compartment is in the nose,
> > accessible
> > > > via a large hatch on top." Canard aircraft don't like big CG
ranges.
> > Why put
> > > > the main baggage compartment in the WORST possible place for that?
> > > >
> > >
Marc McNaughton
Seemed like a really nice guy. He was there showing off the Facetmobile to
its usual big crowd. He must know his stuff - I'D never have the guts to
take that design off paper! :)
As I recall, he was going to build a more sophisticated two-seat version,
possibly for kit sale. Do you know if he's gone through with that at all?
All-in-all a neat concept for a "weekend flyer" sort of plane!
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
ChuckSlusarczyk <ChuckSlusar...@newsguy.com> wrote in message
news:7op57h$p...@drn.newsguy.com...
Marc McNaughton
are held
> by a third party (a bank in Lawrence) in escrow until the kits are
delivered.
> This means that the buyer's monies are not being used as development
capital,
> and are therefore not at risk.
Now that's a very good thing. I've heard too many cases of companies giving
in to temptation and spending the deposit money resolving development
problems when they pop up. At least this way Marv and company are likely to
get their hard-earned dollars back in case the project/company folds.
> The splash may be helpful for securing development capital. I don't know
where
> that capital is coming from, though. Why is "lots of splash" not a good
thing?
It's not so much that I think "splash" is bad in and of itself. Heck,
they'll never make enough sales without advertising. It's just that it's
awfully early for this sort of thing. They don't have a product yet. They're
promoting something that doesn't yet exist. And taking deposits for it. That
makes me think that the owners/founders think this process is going to be
smooth one and that the airplane will fly perfectly right "off the drawing
board." That's usually not a realistic attitude. Problems come up and need
to be solved. That's normal. But it takes money and I'd rather see them
stash the cash they're using for promotion against the day that a flight
test problem develops. If all goes well, the money will still be there when
they're ready to start promoting. Maybe I'm too conservative, but even
conventional designs usually have some sorts of problems once flight test
begins.
> I think the 270# weight is the single-seat rigged Valkyrie. Not much
weight
> saved there, but some. Also it may reflect "weight saving" techniques
that
> didn't (or haven't yet) panned out. For example, they were going to use a
> carbon fiber laminate for the main gear, but have since opted for a more
> conventional chromalloy gear. That cost them a few pounds, but it
probably
> hasn't made its way into the literature.
Well, on their website the empty weights are listed as "240/270 pounds,"
which is the way all of the single-seat/two-seat differences are listed. You
may be right that this information isn't up to date. I hope so. I don't
doubt that the two-seater's weight will be creeping up. Trouble is, a rough
estimate looking at the design suggests to me that 550-650# is probably more
realistic. I know they're using some pretty advanced materials for a
homebuilt, but that design has a lot of bent load paths and the
wing/boom/canard attachment points are going to be heavy too, since these
items are designed to be easily removable. The separate seats are going to
weigh a bit and that huge canopy isn't light either. I'm just really
uncomfortable with the thought that at some point they actually believed
270# was possible for a plane like this.
> If you've seen the baggage compartment, you'll realize that this is a moot
> point. :-)
> Unless you're in the habit of carrying small bags of lead shot as baggage,
I
> don't think it will matter. (The baggage compartment shares space with
the
> nosewheel strut. It's very small.)
Well, the small size you speak of is comforting, but there's still a big
problem here: They don't list a baggage weight in the specs, but they do
list a useful load of 730#. Given a 170# pilot, 170# passenger and a full
fuel load of 60# (10gal listed, at 6#/gal), that still leaves 330# for
baggage! Something, quite literally, doesn't add up here! I mean this as a
joke, but maybe they got the useful load and empty weight numbers backwards?
I'd believe a 730# empty weight and a 270# useful load a heck of a lot
sooner than what they've got posted.
Okay, I guess I've bagged on them enough. I hope that they do end up with a
good little plane. I really do like the looks and the basic concept. Even if
it were heavier and faster stalling (which I think is going to be reality),
they'll have a very saleable airplane if it flies well. But someone posted
that they thought the plane had been designed more for its looks than with
an eye for flight qualities. I fear that may be absolutely correct.
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
Russell Kent <ke...@titania.tye.sc.ti.com> wrote in message
news:37B056D6...@titania.tye.sc.ti.com...
Marv Hamm
Thanks for your excellent and detailed post on looking at the "Valkyrie".
I will attempt to answer some of the items that you mentioned, as well
as some items mentioned in other posts.
Some of the info on the DreamWings site does show that they were a
little optimistic in their initial estimates to produce a kit "ready to
ship".
They are using "DARcorporation" of Lawrence, Kansas to help them with
aeronautical engineering design, analysis, and consultation. When they
mention projects "in the works", I think they are referring to design input
from DAR. I would say that virtually their total effort is being devoted to
getting the Valkyrie ready. As a side note, a year ago they were planning
for the Hooligan to be their 1st model offering, but most of the orders and
interest came in for the Valkyrie----so they switched gears.
Structural testing.....They have one of the best setups in the country
available
to them for aeronautical structural testing through the University of Kansas
(Lawrence, Kansas....municipal airport).
Empty weight--270# for 2 seater if used in Pt 103 ultralight---the
upholstered
seats shown in the photo are optional and would be too heavy for the legal
ultralight. Canopy is actually very light, but is also removable, if
desired, and
replaceable with included windscreen for open air and weight savings. They
are looking at a maximum engine weight of about 70# for the legal ultralight
version. (Note: I don't think that they will shorten the fuselage for the
single
seat version---just not include the rear seat.....would allow more "CG
friendly"
storage. ) In the 2 seat configuration, there should at least be some
storage
space behind the rear seat. Additionally, they are talking about designing
an optional baggage pod for the non ultralight versions. Quite honestly, I
am
not really interested in flying this as an ultralight; so they could add
more
structural weight if necessary for the registered version (as far as I am
concerned). I do know that they would really like to avoid two separate
designs if at all possible.
Aerodynamics--airfoil selection--canard--possible pitch trim problems in the
rain. I can't really address the aerodynamic questions. They have had
professional help in designing it, and I am sure that any problem areas
discovered in the flight test phase will be corrected. One really nice
thing
about the modular concept of the aircraft is that you could fairly easily
change
wings to a completely new airfoil, and you have a different aircraft.
Rain---I really
don't think that this airplane will be ideally suited for flight in IMC
conditions to
include rain. But.....who knows ? Ultralight to registered VMC homebuilt
is
probably enough.
Deposits are refundable.
One further note: I have had the opportunity to visit with the DreamWings
team
and their corporate president, John Hunter, at their homesite in Lawrence,
Ks.,
as well as Sun 'n Fun, and Oshkosh. I do not believe that this project is
about
"money". They may or may not be doing things in the "typical way", but in
my
opinion, it is very important for them to "get it right" before the customer
gets the
product.
Best wishes and once again, Marc, thanks for an excellent analysis and
post.
Marv Hamm
David
> I met Barnaby once at the Flabob airport (CA), airshow several years back.
> Seemed like a really nice guy. He was there showing off the Facetmobile to
> its usual big crowd. He must know his stuff - I'D never have the guts to
> take that design off paper! :)
>
> As I recall, he was going to build a more sophisticated two-seat version,
> possibly for kit sale. Do you know if he's gone through with that at all?
> All-in-all a neat concept for a "weekend flyer" sort of plane!
>
Barnaby has a web page at http://members.aol.com/slicklynne/facet.htm
He describes in it the changes to the Facetmobile (throw away the 2-stroke
and install a Jabiru 2200) and a four-place design that looks really
interesting but is presently shelved due to lack of financial resources.
Any deep pockets out there?
David
N82GT
Ian Robinson
Beautiful - ish, but unless I am mistaken, for the specified wing area and
stall speed, the CL would have to be a completley unrealistic 3.97 at
MTOW.
Ian
Mike Sieweke
I guess the stall speeds are based on the FAA's requirements for an
ultralight. The FAA does not require ultralights to meet stall regs
at MTOW, only with a "standard" pilot and full fuel - 30 lbs fuel plus
170 lbs pilot. At that loading (454 lbs) the Cl is only about 2.3.
This may be possible if their slotted flaps work well.
My bigger concern is their choice of the 63615 airfoil. In "Theory
of Wing Sections" the 63615 shows a tendency toward a sharp stall at
lower Reynolds numbers. They would be much better off using the
63418 or 63618, both of which have much softer stall characteristics.
Also, the 63615 has a high moment coefficient, which causes excessive
trim drag at higher speeds. The airfoil's aft loading will cause high
aileron loads, leading to aileron stiffness.
The 18% thick sections have very little drag penalty, softer stalls,
wider low-drag range, and more space for structure. An even better
choice would be one of the GA airfoils from Harry Riblett's book,
which are modern cleaned-up versions of the old NACA airfoils with
soft stalls, moderate moment coefficients, and less aft loading.
--
Remove the "nospam" from my address if you reply.
Mike Sieweke - msie...@nospam.ix.netcom.com
Yamhill, OR - http://www.netcom.com/~msieweke
Marc McNaughton
> of Wing Sections" the 63615 shows a tendency toward a sharp stall at
> lower Reynolds numbers. They would be much better off using the
> 63418 or 63618, both of which have much softer stall characteristics.
And my calculator says the Rn of the canard MAC at "stall" speed is about
250,000! Eeesh! You'd want a sharp stall from the canard airfoil for good
stall safety, but since they're also saying the airplane can spin (and it's
three-surface - yikes!) that means the main wing is going to break sharply
as well.
My concern was/is that the 63-615 is also Rn-sensitive for Clmax, as well as
roughness. Get this bird (as spec'd on the website) low and slow in a light
drizzle and you're likely to have a great lawn dart. The -418 and -618
aren't much better for this, although the main wing is flying at a higher
Rn.
--
Marc McNaughton
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
Mike Sieweke <msie...@nospam.ix.netcom.com> wrote in message
news:msieweke-110...@prt-or3-51.ix.netcom.com...
ChuckSlusarczyk
>
>
>Beautiful - ish, but unless I am mistaken, for the specified wing area and
>stall speed, the CL would have to be a completley unrealistic 3.97 at
>MTOW.
>
>
My point exactly,when I saw that I lost interest in the rest of the project
except to say "well it's a nice static display model" .I'll just watch and
wait....
Chuck Slusarczyk
Marv Hamm
Ian Robinson wrote in message ...
Beautiful - ish, but unless I am mistaken, for the specified wing area and
stall speed, the CL would have to be a completley unrealistic 3.97 at
-------------------------------------------
Ian,
I don't believe that the stall speeds at MTOW (1000#) are published on the
DreamWings site. What speed did you use ? They are showing
28 & 31 mph stall speeds for the 1 & 2 seat legal ultralight configured
models
respectively. My understanding is that the U.S. Part 103 stall speed
requirements
should be the stall speed for the max empty weight
(of 254# and 270# respectively) + 170# allowed for the pilot + (and I am not
sure on this point) fuel to make it fly---1 seater is allowed max of 5
gallon
capacity, 2 seater is allowed max of 10 gallon capacity. I am not sure if
there
is a requirement to fuel to capacity for a test or not, but if so, you would
be
looking at about 30--60#. So.....the published stall speed numbers should
be based on about 500# or less.
Marv Hamm ( DFW ) mjh...@home.net
Marc McNaughton
speed at MTOW for most applications. A 170# occupant is the FAA "standard
human" and is generally used for such calculations. So... an ultralight with
a 170# occupant and full fuel should be very close to MTOW.
Dreamwings does indeed post stall speed values for the UL and two-seat
Valkyrie on the web site. They are 28 and 31mph respectively. Using the
total lifting area (wing + canard = 102.68sq. ft.), I get an average CL at
31mph and 1000# of 1.98, which isn't out of line for this airfoil, planform
and flap combo, under normal conditions at least. As I've mentioned before
though, I seriously doubt the airfoil used will be providing anywhere near
the published Cl at this low speed.
--
Marc McNaughton
Primary Color
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
Marv Hamm <mjh...@home.net> wrote in message
news:Cxos3.1283$_H....@news1.rdc2.tx.home.com...
Ian Robinson
McNaughton <Xmar...@home.com> writes
>Just to toss in a point here, it's customary to calculate minimum flying
>speed at MTOW for most applications. A 170# occupant is the FAA "standard
>human" and is generally used for such calculations. So... an ultralight with
>a 170# occupant and full fuel should be very close to MTOW.
If you don't calculate minimum flying speed at MTOW your not calculating
for the worst permitted load condition.
>Dreamwings does indeed post stall speed values for the UL and two-seat
>Valkyrie on the web site. They are 28 and 31mph respectively. Using the
>total lifting area (wing + canard = 102.68sq. ft.)
Agreed
> I get an average CL at
>31mph and 1000# of 1.98, which isn't out of line for this airfoil, planform
>and flap combo, under normal conditions at least.
Using the standard formula: L = 0.5*rho*Vs^2*S*CL
Lift in lbs, L = 1000
Wing + Canard Area in square feet, S = 102.68
Density of air in slugs/ft3, rho = 0.00238
Stall speed in ft/sec, Vs = 45.477 [31mph*1.467]
Rearranging the equation:
CL= 1000/[0.5*0.00238*45.77^2*102.68]
CL=3.957
Ian
Ian Robinson
sarczyk...@newsguy.com> writes
>>stall speed, the CL would have to be a completley unrealistic 3.97 at
>>
>>
>>Ian
>
>My point exactly,when I saw that I lost interest in the rest of the project
>except to say "well it's a nice static display model" .I'll just watch and
>wait....
>
>Chuck Slusarczyk
>
>www.cgsaviation.com
>
No it will fly.
I'm only querying the stated/implied performance, about which I'm
sceptical. As already stated by someone, the fact that they have produced
what they have, deserves a lot of credit.
Ian
Mike Sieweke
> And my calculator says the Rn of the canard MAC at "stall" speed is about
> 250,000! Eeesh! You'd want a sharp stall from the canard airfoil for good
> stall safety, but since they're also saying the airplane can spin (and it's
> three-surface - yikes!) that means the main wing is going to break sharply
> as well.
It's not a canard in the traditional sense. That front winglet is only
there to look cool. Maybe they designed it so it cancels out the high
pitching moment of the main wing, but either way it's not there to provide
stall safety. With the flaps deflected it won't be doing much.
I agree with you about the low RN effects. There are lots of surprises in
store for the Dreamwings test pilot.
Also, three-surface airplanes have their own special problems. Look at that
Australian/Malaysian one (Eagle 150) that has vortex generators, wingtip
droops and stall dams on the main wing to make up for being in the wake
of the canard. I expect the Dreamwings folks will be looking at similar
design changes once they get one flying.
Marc McNaughton
> CL=3.957
Damn. I forgot the "1/2." Bad calculator! Bad! :)
Ian is right. It's about 3.96.
--
Marc McNaughton
Primary Color
Irvine, California
Please remove the "X" at the beginning of my e-mail address if you wish to
send to me directly. I hate spam!
Ian Robinson <i...@idrarch.demon.co.uk> wrote in message
news:9t16rEAM...@idrarch.demon.co.uk...
Marcin Kolbuszewski
but we all have to wait
to see whether it flies, and how it flies
Now have a look at www.moller.com and its "vehicle" Skycar
4 passengers, cruising 350mph, climbing 7800 fpm on 960HP and 15 mpg. aha gross
weight 2400 lb,
payload with max fuel 740 lb and range 900 miles.
Can anyone beat these specs?
BTW deposit is only 5000 bucks.
Cheers!