Canard Community Forum  

Go Back   Canard Community Forum > Plane Specific Questions Tips, Tricks Area for All Canard Kits and Plans Planes
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #61  
Old 08-06-2004, 08:28 AM
crashdog's Avatar
crashdog crashdog is offline
Crash
 
Join Date: Apr 2004
Location: Toronto
Posts: 34
Default

I have been following this thread with a lot of interest. A six or eight place canard configuration is perfect, so much so that it has been tried a number of times (BeechStarship, AASIJetCruzer, PiaggioAvanti) I have noodled this issue independently over the last year or two, and have drawn up some models in AirplanePDQ, Rhino3D, and have even tried flying them in XPlane. Next step is some CFD and FE analysis.

By the way, the models have not flown well! However, the idea is to get the rough parameters done up, then work closely with a designer to get it right. In other words, spend a bit of money. However, given that it is a big project, a little money at the front end makes sense.

My inclination is toward a 2,2,3 with the middle 2 club rearward, and the rear 3 a bench. This allows the two middle lots of room when flying 4, and allows ingress to the "cabin" through a side door, likely a split upper/lower.

I like the idea of counter-rotating props with centre-line thrust. Lots of engineering to be done, but again, working with an engineer will facilitate this. I would think that two 13bs driving the counter-rotating props would work. I am a little disappointed about Perry Mick's experience with the shrouded fans, but there probably is more work that could be done there, particularly in software modelling.

Have a look at www.equatorac.com. Some interesting ideas there.
Reply With Quote
  #62  
Old 08-06-2004, 09:02 AM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Quote:
Originally Posted by crashdog
I like the idea of counter-rotating props with centre-line thrust. Lots of engineering to be done, but again,
Center-line thrust, I agree that would seem to be the better setup. It seems like a Defiant is an all-around fitting solution. Get yourself a 20year loan and just buy one, or a cherokee-6. Use your building time to be with the family while they're still young and do what you do best to make money to further your career. When they get to their upper teens they won't want to be around or will have multiplied and you'll need a 10-seater. Ok, I see the the telescoping Proteous coming in here(it really can).

Quote:
Originally Posted by crashdog
I am a little disappointed about Perry Mick's experience with the shrouded fans, but there probably is more work that could be done there, particularly in software modelling.
Last year I watched the launch of a ducted fan which clearly wasn't getting adequate power out of the thing and it went off the end of the runway. It could've used the freeway and never have gotten enough speed to fly. I'm sure if the same motor was rigged to a normal prop it would've flown just fine. It sure made alot of noise though. Nobody was hurt since at 24" in length it was too small to carry anyone.

Regarding the Equator. I once fancied that kind of layout. You know of course that there's a serious struggle between the motor trying to push it nose-down and the tail trying to keep the nose up. Also, I notice on this low-wing version, which has no flying pics yet, they do make the mistake of tapering the fuselage where the wing is thinning to the trailing edge.

Last edited by tnt : 08-06-2004 at 09:14 AM.
Reply With Quote
  #63  
Old 08-08-2004, 02:40 PM
MarbleTurtle's Avatar
MarbleTurtle MarbleTurtle is offline
Member
 
Join Date: Apr 2004
Location: Dalton, GA.
Posts: 1,344
Default

Here's evidence that a big enough motor can drag any pig into the air...

http://www.barraircraft.com

Six passengers at 200mph, not bad... but it looks like the 172 before Jenny Craig.
__________________
Past performance is no guarantee of future results.
Reply With Quote
  #64  
Old 08-08-2004, 05:34 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

He made a mold from a Cessna 207, a stretched C206. I've got at least 100 hours in one.
Reply With Quote
  #65  
Old 08-09-2004, 04:20 PM
Wapati8's Avatar
Wapati8 Wapati8 is offline
Member
 
Join Date: Jul 2004
Location: Austin Texas
Posts: 82
Default Things that might be incorporated in the SixZ

Here is some food for thought. I was browzin the Rough River website and I found some encouraging photos and descriptions...


Mike Bowden's Jabiru powered Twin EZ
This unique Twin EZ flew up from Smyrna Tennessee to rough river 2001.

Does anyone know if this plane is still flying?



If you used the counter rotating reduction drive from RWS on one side and the regular regular reduction drive on the other side would this eliminate the left hand turning tendancy mentioned earlier?


A defiant at RR 2002
A defiant pusher puller configuration might be good for a six+ seater... comments?


This shot was just cool



13b engine configured for aviation use

Last edited by Wapati8 : 02-20-2007 at 11:52 PM.
Reply With Quote
  #66  
Old 08-09-2004, 05:41 PM
LargePrime's Avatar
LargePrime LargePrime is offline
redesigning every part before build
 
Join Date: Apr 2004
Posts: 502
Default

Wapati8;
You asked what was better, one big prop or two small ones.

I suggest that one big prop is better. Prop efficency is based on the cube of the diameter, so a big prop should be more efficient. Small props gain you nothing.

I dont know of a six seater that has over 400 HP. All the ones I know are 300-325. There fore i think it is just silly to consider twin rotarys. But I like silly.

The seating arrangement of four in the back facing each other is great. the white lighting did something simular.

You would have less drag with a 3+3 tho.

Have any of you see mike arnolds videos? He has a hot wire technique for making fuses that i think would work well for this kind of project.

Have you all considered a blended wing body type thing.
Reply With Quote
  #67  
Old 08-09-2004, 07:18 PM
ShaleDC ShaleDC is offline
Member
 
Join Date: May 2004
Location: Alexandria, VA
Posts: 673
Default

Quote:
Originally Posted by LargePrime
Wapati8;
I suggest that one big prop is better. Prop efficency is based on the cube of the diameter, so a big prop should be more efficient. Small props gain you nothing.
...Except that with a big prop & a big engine, the tips of the prop inevitably go supersonic, with a big loss in power.
Reply With Quote
  #68  
Old 08-09-2004, 07:29 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Quote:
Originally Posted by Wapati8
If you used the counter rotating reduction drive from RWS on one side and the regular regular reduction drive on the other side would this eliminate the left hand turning tendancy mentioned earlier?.
I'm sure counter rotating would be take care of prop-induced turn tendencies but I don't know where you would find a matched set of counter-rotating motors or re-drives.

Quote:
Originally Posted by LargePrime
I suggest that one big prop is better. Prop efficency is based on the cube of the diameter, so a big prop should be more efficient. Small props gain you nothing..
Good point but I dont think he was proposing 2 small props.

Quote:
Originally Posted by LargePrime
You would have less drag with a 3+3 tho. .
I don't see this. And what fun is it to agree.

Quote:
Originally Posted by LargePrime
Have any of you see mike arnolds videos?.
Yea, I've got them too.

Quote:
Originally Posted by LargePrime
Have you all considered a blended wing body type thing.
Looks cool but I think that project is seriously floundering. There's gotta be something seriously wrong with the design. The reason they are thinking a jet must be because a pusher-prop wont work on it, too much air-blockage by the body. And I think that really cool wing sweep is practically excessive. They prolly find it requires a really high takeoff/landing speed to stay safe from stalls and dutch-rolls.
Reply With Quote
  #69  
Old 08-09-2004, 10:07 PM
John Slade's Avatar
John Slade John Slade is offline
Flying TurboRotaryCozyIV
 
Join Date: Apr 2004
Location: KWST
Posts: 3,836
Default

The reason for going with a twin is not necessarily to make the best efficient use of the power - it's to keep half of it if the other half dies and therefore add confidence and attractiveness to the design. I still vote for twin 13Bs. Perhaps Tracy could be persuaded to make a counter rotating 2.17 redrive.

By the way - that rotary would never fit under a Cozy cowl with the intercooler on top like that.
Reply With Quote
  #70  
Old 08-10-2004, 10:10 AM
LargePrime's Avatar
LargePrime LargePrime is offline
redesigning every part before build
 
Join Date: Apr 2004
Posts: 502
Default

This is the thread in which we get to pratice our quoting skills

Quote:
Originally Posted by John Slade
it's to keep half of it if the other half dies and therefore add confidence and attractiveness to the design.
This is not a redundant engine system.
As noted by dust, lose one engine and you lose 90% of your performance. The old addage that the second engine is there to get you to the site of the crash is not without truth

Quote:
Originally Posted by tnt
Quote:
Originally Posted by Wapati8
If you used the counter rotating reduction drive from RWS on one side and the regular regular reduction drive on the other side would this eliminate the left hand turning tendancy mentioned earlier?
I'm sure counter rotating would be take care of prop-induced turn tendencies but I don't know where you would find a matched set of counter-rotating motors or re-drives.
Lets check our premise.Is there a prop effect noticable when flying the cozy?
Quote:
Originally Posted by tnt
Quote:
Originally Posted by LargePrime
You would have less drag with a 3+3 tho.
I don't see this. And what fun is it to agree.
This goes along with my Burnelli (since NASA stole it from Burnelli. www.aircrash.org) Wing Body (BWB) comment.
If you look at a profile of the EZ you see a wing. Replace the strakes with a wing blended into the body and you got a BWB.
I am not talking about wingco, or anything else. Just a simple mod to the ez design that truns it into a BWB.
If you read "Low Power Laminiar Aircraft Design" the author comments on how a wide stubby airfoil shaped fuse has much less drag than a traditional long tube body.
Quote:
Originally Posted by ShaleDC
Except that with a big prop & a big engine, the tips of the prop inevitably go supersonic, with a big loss in power.
Supersonic is not the intent. If one uses the 2.85 drive from tracy one could spin a 72-80" prop nice and slow on a rotary.
Reply With Quote
  #71  
Old 08-10-2004, 11:25 AM
Turbotag's Avatar
Turbotag Turbotag is offline
Designing new canard
 
Join Date: May 2004
Location: Spirit Lake, IA
Posts: 50
Default

[quote=LargePrime]
This goes along with my Burnelli (since NASA stole it from Burnelli. www.aircrash.org) Wing Body (BWB) comment.
If you look at a profile of the EZ you see a wing. Replace the strakes with a wing blended into the body and you got a BWB.
I am not talking about wingco, or anything else. Just a simple mod to the ez design that truns it into a BWB.
If you read "Low Power Laminiar Aircraft Design" the author comments on how a wide stubby airfoil shaped fuse has much less drag than a traditional long tube body.

QUOTE]

Interesting idea but I doubt its usefullness is such a small vehicle. With the rounded top of the fuse you are disapate the differential pressure [lets not get into a debate on the various theroies of lift HERE]. You have to look at the fuse in 3 dimensions not just section through the centerline. I personally am a fan of the BWB design, on vehicles where it makes sense. And remember with lift comes drag. So if you can't generate "efficient" lift from the fuse you have to go to minimum drag designs. This is why the tube became so popular, especially for small vehicles. I also have concerns with large flat verticle surfaces doing funny things in cross winds.

If we stick to the twin per Mr. Slade the rotary has plenty O'power even if we increase the weight with variable pitch props. The beauty of the roatary to me is the cost per HP. Am I going to run both rotories at 200hp? probably not. Part of the reason I am working on the Mark VI is to come up with a "buildable" 6 place. The Twin, to me, solves some reliabilty concerns that some have with automotive conversions AND I believe cooling will be much easier to deal with with the engine mounted in their own airstream.

Propellor sizing is a fine art....2 or 3 blades, diameter, twist, which airfoil(s). All to match the flight conditions you are most interested in. I haven't seen an equation that equated prop efficency with cube of the diameter. but that doesn't mean it doesn't exist. Just as the lift generated by an airfoil is THEORY a propellor is a magnitude greater in theory(speed, acting in the wake of other airfoils, etc.).

Just my 3 cents.

PS. I found the aircrash.org site interesting. While I sympathizes with the Burnelli company and I think that their design is great, it is not the be all end all they claim. Their graphic of the conventional airliner was interesting. But someone please correct me if I am wrong but I have never seen fuel tanks in the horizontal stabilizer of any plane.
Reply With Quote
  #72  
Old 08-10-2004, 12:53 PM
LargePrime's Avatar
LargePrime LargePrime is offline
redesigning every part before build
 
Join Date: Apr 2004
Posts: 502
Default

Quote:
Originally Posted by Turbotag
With the rounded top of the fuse you are disapate the differential pressure
Pardon? A left to right differential pressure? Please explain.
Quote:
Originally Posted by Turbotag
And remember with lift comes drag. So if you can't generate "efficient" lift from the fuse you have to go to minimum drag designs.
Wetted area creates drag. The question is if the wetted area is pulling it's own weight. If it's not creating lift it is just drag. Any lift is better than none.
Quote:
Originally Posted by Turbotag
This is why the tube became so popular, especially for small vehicles.
Simply untrue. Why the tube became popular has nothing to do with efficency of flight. It has to do with Bias.
Quote:
Originally Posted by Turbotag
I also have concerns with large flat verticle surfaces doing funny things in cross winds.
Please explain your concerns.

Quote:
Originally Posted by Turbotag
If we stick to the twin per Mr. Slade the rotary has plenty O'power even if we increase the weight with variable pitch props. The beauty of the roatary to me is the cost per HP. Am I going to run both rotories at 200hp? probably not. Part of the reason I am working on the Mark VI is to come up with a "buildable" 6 place. The Twin, to me, solves some reliabilty concerns that some have with automotive conversions AND I believe cooling will be much easier to deal with with the engine mounted in their own airstream.
Look at the defiant. 300+hp and slower, heavier, and much more complicated than a cozy that lifts the same payload, same cabin, better performance.
You do not get reliability from twins. You get twice the engine problems and much more weight.
Reply With Quote
  #73  
Old 08-10-2004, 01:53 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Quote:
Originally Posted by LargePrime
Lets check our premise.Is there a prop effect noticable when flying the cozy?
How does a standard cozy's behavior relate to my earlier post of the reported left-turning tendency of the twin VariEze and the resulting question of whether counter-rotating props might be helpful to counter it?
Reply With Quote
  #74  
Old 08-10-2004, 02:28 PM
Turbotag's Avatar
Turbotag Turbotag is offline
Designing new canard
 
Join Date: May 2004
Location: Spirit Lake, IA
Posts: 50
Default

Wow Largeprime,

Is this a test?

NOT left to right but tangental to the surface.

1. Just because you have a shape similar to an airfoil does not mean you will create lift. If you do happen to create lift with your profile you will also create drag (I will get back to this). Some airfoils exihibit nasty drag and pitching moment polars. There are many many NACA reports on airfoils that someone thought was good for some reason or another and when investigated was found to be deficient.

2. The section through the center line of the Cozy appears somewhat like an airfoil but you have a big dent in it right where you should be developing your lowest pressures. How does this 2d airfoil perform? I don't know but I would guess that it does create some differential pressure since the path over the top of the airfoil is longer than the bottom path. But I would also bet that the drag would be pretty bad. In our 3-d world the air has more than 2 choices. It can also be pushed sideways. What does the section through the Cozy look like at +- 3 inches from the center line. Is it an efficient airfoil or something less? Is the surface that the differental pressure is projected from still forward and up (for the front portion of the airfoil) or is it now up, forward and Right/left. The vertical portion of the vector has gotten smaller so how does it compare to its compliment on the bottom of the fuselage?

The tube did not develop out of bias...at subsonic speeds the tear drop shape generates the least drag. It also requires the least energy to return to its original heading when preturbed. This is why drop tanks, wheel pants, and nose cones are rounded. The Cessna Dragonfly had major problems in pitch because it had a big flat nose. They ended up adding a chine to it. In yaw perturbations a rounded shape requires the least energy to return to its original state.

Kelly Johnson considered one of the great designers of all time made the "pilot pod" on the P-38 a tear drop not a lifting body. Was that out of bias?

AGAIN let me state that I am all for WBW aircraft in the right mission, and the EZ could probably be redesign to incorporate this technology. I am just not sure how much you would really gain. As far as Burnelli's claim of conspiracy I am having a hard time swallowing. Were they wronged yes. Are these ancient reports still hurting the design? I am not buying it. Many small companies have overcome the bank bias to produce great products but sometimes you have to take an indirect path. I don't remember banks flocking to Burt Rutan but now his company Scaled composites is on the verge of winning the X prize. If Burnelli's design is that efficient go out and prove it on a smaller scale. (but bigger than the EZ) Northrup survived the Secretary of Defense's corupt desire for them to merge with Consolidated. Even though the YB-49 was a superior design to the B-36 Peacemaker. They lost and moved on. And the B-2 years later proved Jack was ahead of his time.

Wheewww now I need a break.

Thanks Largeprime for the exercise and I look forward to more on this subject.

Tim


http://www.fact-index.com/l/li/lift_induced_drag.html
Reply With Quote
  #75  
Old 08-10-2004, 03:44 PM
LargePrime's Avatar
LargePrime LargePrime is offline
redesigning every part before build
 
Join Date: Apr 2004
Posts: 502
Default

No, its not a test.
I'm having fun, aren't you? If not let me know.

I misunderstood your assertion about the canopy. I agree that the cozy is not perfect for a BWB. But that’s not the point.

While it is not ideal, indeed many things are less than perfect, the point is that we have a very stable test bed for and interesting variation of the EZ design.

Blended strakes would give more cargo and fuel room, desperately needed if we are talking about a 6+6, and possibly contribute lift that offsets the increased form drag. They cant be worse than a tube.

We would have to pick a good forgiving airfoil. We would have to test it. We would be developing a whole new plane. So? Is there anything cooler than flying a BWB Canard?

EDIT
TNT There is now a BWB cozy thread. Want to copy this stuff, or just the relavant parts, there?
END EDIT

On to tubes.

A tube is not a tear drop. You talk about tubes then move right on to teardrops, as if they are related. I don’t understand the connection.

I assert that the tube did develop out of bias. As the FAA regulated innovation out of the industry, every one else did what everyone else was doing. That’s why all airliners look alike. Now the tube has uses, and is good for a few things, but an aerodynamically efficient aircraft is not one of them.

I disagree with your assertion that a tear drop has the least drag. It is misleading. You would agree a wing shape will require less energy to fly than a tear drop and the wing to get it to fly.

About Burnelli
Burnelli had the right idea 90 years ago. He built flying examples 85 years ago. His ideas are as relevant an important today as they were when he invented them. For Nay Say to claim to have invented an idea 70 years after he invented it is silly.

Google NASA.gov for Burnelli. How many hits? perhaps a coincidence, but pick any other big name designer see if you get a hit. I tried a few and they all hit.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 05:06 PM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.