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View Full Version : Could soundbarrier be broken with a prop plane ?



First time Juke
02-11-2009, 01:44 AM
I have been wondering since this 7.5 meters long Merlin pusher seemed pretty hot...and able ?

I mean all aerodynamics fitted to receive all buffeting at transonic speeds...or would R3-A5 loose a prop at mach 0.91 like Spitfire Mk XI did way back when ?

JET1
02-11-2009, 11:53 AM
..I think a 'pusher' is the only way a prop plane could break the sound barrier but it would take a very creative propeller design. at high manifold pressure and rpm a p-51 generates a shock cone in front of the plane that is hard to defeat except maybe in a dive.....or so im told

First time Juke
02-11-2009, 12:05 PM
Baloney Slicer prop ?

If that ever happened the pilot would have his name written in aviation history permanently.

Inverted
02-11-2009, 04:48 PM
A piston plane can break the sound barrier yes, whether the prop holds up or not is the problem. Curently no bladed aircraft engine can take the sound barrier that I know of, jet aircraft have ways to disrupt airflow into the engine so the engine its self does not go supersonic.

LearFanKid
02-11-2009, 06:26 PM
I have been wondering since this 7.5 meters long Merlin pusher seemed pretty hot...and able ?

I mean all aerodynamics fitted to receive all buffeting at transonic speeds...or would R3-A5 loose a prop at mach 0.91 like Spitfire Mk XI did way back when ?

Very cool looking airplane!

Leo
02-12-2009, 10:38 AM
IF it was designed to do it and you could design a prop to operate at the speeds needed. Myths and claimes notwithstanding, the WW2 fighters reached their top speed long before Mach 1. The P-51, P-38, P-47 and Spitfire all reached speeds where compressibility effectively limited them both by drag and structure.

First time Juke
02-12-2009, 10:54 AM
Quite right Leo.

R3-A5 would have to look a bit like Mach Buster and have pretty thin airfoil ( and wide wing ).

One little rock at take off hitting the prop would ruin the whole project !:eek13:

I'd have to built the Max III ( in my blog ) to get familiar with problems possibly having to face in rear propped ac.

Illfated Lars Giertz had also flown Bede-5B before testflying his small winged slick VmaxProbe.

PS: I have updated heavily my blog writings.

First time Juke
02-14-2009, 08:21 AM
A piston plane can break the sound barrier yes, whether the prop holds up or not is the problem. Curently no bladed aircraft engine can take the sound barrier that I know of, jet aircraft have ways to disrupt airflow into the engine so the engine its self does not go supersonic.


I have another concern...would that scoop blow away at mach .84 ?

Inverted
02-14-2009, 08:59 AM
which scoop?

First time Juke
02-14-2009, 12:52 PM
The air intake scoop underside of the R3-A5...above ( two seater ).

My computer is running so slow I think its gonna blow soon.

Reno_Steve
02-15-2009, 10:04 PM
If the rule was top speed of a piston engined plane, would use of a ducted fan allow higher speed than a propeller ?

First time Juke
02-16-2009, 12:39 AM
If the rule was top speed of a piston engined plane, would use of a ducted fan allow higher speed than a propeller ?


I don't think so. Jet-engine needs a tube...and prop needs the air.


No one ever built ( ok...flew ) a pusher with enuf power to even try braking the sound barrier.

To demand to build a fast interceptor for FAF State AC factorys chief engineer Ylinen designed Puuska fighter with retractable radiator. That could solve the problem...use little less radiator area at higher speed.

First time Juke
02-16-2009, 11:07 AM
Loks like M B I people had some glue about the matter:

http://www.angelfire.com/moon/cheese1/machbuster.html

AirDOGGe
02-16-2009, 09:01 PM
From what I have seen, the drag of the duct in the airstream of forward flight seems to take away any advantage of the efficiency of ducted fan technology, especially at high forward speeds.

This is one reason the airline manufacturers are starting to lean towards developing un-ducted fan technology...less drag/higher efficiency.

RB77fan
02-16-2009, 09:34 PM
mmmmmm definatly have to bee a pusher toooo much stress on blades

First time Juke
02-17-2009, 01:09 AM
Chris is right..there is lotsa stress on the blades. Since the tips of the blades are what counts...why does both LF 2100 and MB I have so thin end section in the fuse ?

That type will be hard to cope with the vibrations that occur in the prop...I say the end of the plane has to be rock solid. No wonder Burt stated doing Vari-Ez etc after BD-5 project.

Look at the Shinden pusher...ok it was not very succesful but it flew and had lotsa wheels too ...5 altogether.

http://www.youtube.com/watch?v=KL0GFQL1BFo

BTW: Anyone know the Sierra Sue top speed ?

racingjoe27
02-17-2009, 10:24 AM
Chris is right..there is lotsa stress on the blades. Since the tips of the blades are what counts...why does both LF 2100 and MB I have so thin end section in the fuse ?

That type will be hard to cope with the vibrations that occur in the prop...I say the end of the plane has to be rock solid. No wonder Burt stated doing Vari-Ez etc after BD-5 project.

Look at the Shinden pusher...ok it was not very succesful but it flew and had lotsa wheels too ...5 altogether.

http://www.youtube.com/watch?v=KL0GFQL1BFo

BTW: Anyone know the Sierra Sue top speed ?

Lars Giertz explained the reason for having a thin fuse. He said that it is to minimize the disrupted airflow into the prop thereby maximizing the efficiency of the blades.

With material technology nowadays, you could build a small yet robust product that would still help in weight savings (not that weight is an immense issue anymore with the 4500lb rule).

First time Juke
02-17-2009, 10:34 AM
Lars Giertz explained the reason for having a thin fuse. He said that it is to minimize the disrupted airflow into the prop thereby maximizing the efficiency of the blades.

With material technology nowadays, you could build a small yet robust product that would still help in weight savings (not that weight is an immense issue anymore with the 4500lb rule).

That does not make much sense. You have to disrupt the airflow anyhow by the cockpit bulge and the wings and tailfeathers and engine exhausts.

I think this is the reason why BD-5B fuse was so square to spread the air flow more even thus causing less disruption.

I think Giertz cause was more simple...less induced drag like in gliders..unfortunately less drag in fuse means also need for bigger stabilizers...they were minimalistic in VmaxProbe...prop almost looks bigger than the horizontal stab. IMHO

Red
02-17-2009, 05:34 PM
That does not make much sense. You have to disrupt the airflow anyhow by the cockpit bulge and the wings and tailfeathers and engine exhausts.

I think this is the reason why BD-5B fuse was so square to spread the air flow more even thus causing less disruption.



Actually quite the opposite is true. Having the fuse neck down after the cockpit bulge helps reattach the disturbed aiflow. It is called a pressure recovery area. You can see the same pricipal in the NACA laminar section on any P-51 wing. this delays flow separation, thus reducing drag.

The BD-5 was square and boxy for two reasons. One, it was made of metal and needed the box to be strong. Two it needed the area for the Hirth/Subaru/Honda engines it used. There is no transonic aero in that design at all.

You would be surprised to find out how things change aerodynamically when near the speed of sound. Just because it looks slick and fast doesn't make it so.

I suggest a little light (or heavy if you prefer) reading to get a better idea of what you are trying to guess at.

King
02-17-2009, 06:16 PM
Actually quite the opposite is true. Having the fuse neck down after the cockpit bulge helps reattach the disturbed aiflow. It is called a pressure recovery area. You can see the same pricipal in the NACA laminar section on any P-51 wing. this delays flow separation, thus reducing drag.

The BD-5 was square and boxy for two reasons. One, it was made of metal and needed the box to be strong. Two it needed the area for the Hirth/Subaru/Honda engines it used. There is no transonic aero in that design at all.

You would be surprised to find out how things change aerodynamically when near the speed of sound. Just because it looks slick and fast doesn't make it so.

I suggest a little light (or heavy if you prefer) reading to get a better idea of what you are trying to guess at.

And almost all of Jim Bede's designs were boxy because they were easier to build.............except for the BD-10.............very sexy looking but under analyzed with a very tragic outcome. Even the re-analysis of the tail section was done wrong with tragic results.

thunderstangfan
02-17-2009, 06:37 PM
how about this for a little light reading
http://history.nasa.gov/SP-4219/Chapter3.html

Red
02-17-2009, 06:40 PM
Exactly my point. Airplane design isn't about drawing pretty shapes.

racingjoe27
02-17-2009, 06:58 PM
We have all been told that the most aerodynamic design is a teardrop. The point of the tear drop is the pressure relief. It may or may not look good but it sure ie effective.

But in an application with this speed as the goal, the tail feathers could experience area ruling. Just one more thing to think about when you have very limited space and require lots of power.

Red
02-17-2009, 07:17 PM
Ever seen what a raindrop actually does when it falls? The tail is actually from surface tension as it separates. It does some things you wouldn't expect. Pretty enlightening!

I'm sure there is a youtube vid somewhere.

King
02-17-2009, 08:23 PM
Ever seen what a raindrop actually does when it falls? The tail is actually from surface tension as it separates. It does some things you wouldn't expect. Pretty enlightening!

I'm sure there is a youtube vid somewhere.

Whats a raindrop?

heard about those when I was a kid, but we never see those around here.

Thank gosh for youtube.

First time Juke
02-18-2009, 01:39 AM
Actually quite the opposite is true. Having the fuse neck down after the cockpit bulge helps reattach the disturbed aiflow. It is called a pressure recovery area. You can see the same pricipal in the NACA laminar section on any P-51 wing. this delays flow separation, thus reducing drag.

The BD-5 was square and boxy for two reasons. One, it was made of metal and needed the box to be strong. Two it needed the area for the Hirth/Subaru/Honda engines it used. There is no transonic aero in that design at all.

You would be surprised to find out how things change aerodynamically when near the speed of sound. Just because it looks slick and fast doesn't make it so.

I suggest a little light (or heavy if you prefer) reading to get a better idea of what you are trying to guess at.


Ok Red,

I have to explain a bit more ( and don't start patronizing me again ).

I said he wanted to cut down the drag like in gliders..I know that theory and reattachment of the flow...but I specifically said he needed more tailfeather...BECAUSE..thet airflow will not reattach in abnormal flightsituations...it attach only in windtunnel conditions or in level flight.

I agree that BD-5B was not transonic design, but dare to argue about reason why the fuse was square ...it was to get maximum directional stability for small plane like BEDE-5 is. It added drag, but gave more control..I could be wrong about spreading the air flow.

cheers !

Juke

:beerchug:

PS: I am taking back 10 aviation books back to library today ( some of them concern aerodynamics and designing an aeroplane ). Thanks for the link.

First time Juke
02-18-2009, 05:11 AM
Exactly my point. Airplane design isn't about drawing pretty shapes.

Thanks for the compliments Red ( do you mean the Max III gear arragement in my blog ? ).

I think we discussed the problem of going into transsonic region with BLUE FOAM ( Eric Alstrom ) about a decade ago here. The foil issue has been pretty good in memory ever sice.

Those who have joined discussion later this appears perhaps very new.

The wing foil of the transsonic region indeed looks very different from of those that were designed before the discovery of compressibility.

What in fact was also ever since those discoveries taken for granted is how the lift in wing is produced....before everyone said it is Bernoulli and now all agree it is Newton teories that rule.

I have underlined Newton theory ever since I read about it first time..it is also the one I understand.

Alstroms DART and supercritical wingfoil can be found in the web. I think the main problem is windtunnel time....there are few windtunnels capable to reach even transsonic speeds and they are all taken . I say this that Eric doesn't have to repeat it.

Will prop plane go supersonic remains to be seen. I suggest we remain in the topic and discuss the matter at hand. In other words....could it be done ?


--------------------

I go OT immediately:


Here is BTW the VmaxProbe 3-views:

http://www.webcamsue.nl/pagedrw1.gif

The tailfeathers are in good proportion to the wing ( 24 sq ft exposed ).

I just wonder if the pusher actually needs more tailfeathers ( than a tractor lay out ) due to the gyroscopic forces ?

Sierra-Sue and LF 2100 seem to have a lot of tailarea.

Reason why I went OT is that only way to go super sonic with a prop plane is a pusher..and these are the few examples we have.

Red
02-18-2009, 06:59 AM
The prop in a pusher actually addes lateral stability. Case in point: Northrop YB-49. Flew fine with props, re-engined with jets and they had to add vertical surface area. Even though the prop is creating thrust, there is still all the disk area behind the CG which helps.

If you ever get to see a BD-5 in person, you'll get why the fuse is shaped the way it is, and aero s not the reason. There is no room in fuse for any other shape!

What is clear is that yes, a propeller aircraft could be designed to break the sound barrier. The vehicle math is well understood, the shortcoming is in prop design. We'll probably never see it advance far enough to make it feasable for the simple reason is jets do it so much better. An unducted fan is probably the best route.

Red
02-18-2009, 07:21 AM
Ok Red,

I have to explain a bit more ( and don't start patronizing me again ).



I'm guessing English is not your native tongue?:deal: Easy there tiger.

First time Juke
02-18-2009, 09:05 AM
I'm guessing English is not your native tongue?:deal: Easy there tiger.


No Red..my native tonques are finnish and swedish.

I hasn't stop trying to speak english before.

But I do misspel length as lenght every now and then.


Here is a Tiger for ya ( finnish rock band from early eighties )!

http://www.youtube.com/watch?v=LOwObMbuKg0


I added a pic with Vmax probe and BD-5 profiles in same scale at my site.

First time Juke
02-18-2009, 11:29 AM
The prop in a pusher actually addes lateral stability. Case in point: Northrop YB-49. Flew fine with props, re-engined with jets and they had to add vertical surface area. Even though the prop is creating thrust, there is still all the disk area behind the CG which helps.

If you ever get to see a BD-5 in person, you'll get why the fuse is shaped the way it is, and aero s not the reason. There is no room in fuse for any other shape!

We'll probably never see it advance far enough to make it feasable for the simple reason is jets do it so much better. An unducted fan is probably the best route.

YB-49 case may be so but XB-42 did suffer yaw problems; http://en.wikipedia.org/wiki/XB-42_Mixmaster

One thing that bugs me is the long distance from the prop to the aerodynamical center in rod connected fan pushers. The gyro forces really do exist and lot more effective area thus needed in elevator rudder section.

What about situation where engine siezes..and stop propelling the thing ? again the ailerons have to compensate and are far from tha cause of the twist...this was a big problem in P-51D ( increase of power at low speeds caused bank to the left ).

I have to start believing you Red in this Bede-5b size matter...it has a lot of radiator and use of the tricycle retractable landing gear also takes room.

Why I think pushers will inevitably win is the less gas burning layout travelling at reasonably fast speed...evident also in XB-42. Jetmaster XB-43 with same frame wasn't much faster: http://en.wikipedia.org/wiki/XB-43_Jetmaster

First time Juke
02-18-2009, 11:43 AM
Scott Pullman !


Here is another one for them ( out from my blog ) !

Thanks for rising the spirits here.

:thumbsup:

Keep posting and welcome to the forum !

Leo
02-18-2009, 11:44 AM
The YB-49 and Mixmaster are apples and oranges. The XB-35 flight descriptions mention nothing about lateral instability, maybe because it did not fly much, whereas one of the reasons for the YB-49's "failure" was it's instability and tendancy to wander which made it a weak bombing platorm. The P-51 had weakened lateral stability when the razorback was removed, never adequately solved until the taller tail of the H (The dorsal on the D helped).
I have no idea what the result of all those blades spinning far back of the wing on a mixmaster would do to it's handling. Wasn't the RB-51 a little weak laterally also, resulting in the large tail and at some times in it's career a dorsal?
I would agree with Red on the BD designs tho, everything he did was a little boxy, I feel due to a combination of needed room and simplicity of design and construction.

Leo
02-18-2009, 11:47 AM
Spullsit, I did something similiar by taking a bunch of my pics and using the coloring book setting to change them. Aircraft, cars, landscapes. Her pre-school class loved them!

Red
02-18-2009, 12:19 PM
You got it right Leo. The propellor is a destabilizing force (it has disk area among other things) ahead of the CG. When you change that (ie add blades) there has to be something to counter that force, which is why you see more tail on the modded planes like the Bear, Furious, RB, CM, PM etc..

First time Juke
02-18-2009, 02:35 PM
How does bringing the wing and tailmounted prop on the same axis affect in stability ?

I see Mixmaster had it..but LF 2100 had them pretty far apart..could this be the cause of the loud bangs in the structure Mr. Penney informed in the LF 2100 thread when flying it...that caused the people at LF 2100 to make a new wing again etc.?

Hey and thanks all the comments Red, Scott, Leo and all ! My pusher needed them...:thumbsup:

First time Juke
02-20-2009, 01:35 AM
Ever seen what a raindrop actually does when it falls? The tail is actually from surface tension as it separates. It does some things you wouldn't expect. Pretty enlightening!

I'm sure there is a youtube vid somewhere.

Here is a story about raindrops...not very aerodynamical.

http://ams.allenpress.com/archive/1520-0469/11/6/pdf/i1520-0469-11-6-478.pdf

I recall this myth about raindrops being somewhat ideal aerodynamical form has been broken long ago. Strange it still lives on strong.

I remember it was repeated over and over again when Pik-20 the sailplane was being marketed.


Stop this vid at 1 sec to see a drop before impact.

http://www.youtube.com/watch?v=CJ-AX1G0SmY&feature=channel

Peashooter
02-20-2009, 05:23 AM
BTW, Col. Joe Kittinger went supersonic with no airplane at all!

http://en.wikipedia.org/wiki/Joseph_Kittinger

SpinB
02-20-2009, 02:41 PM
BTW, Col. Joe Kittinger went supersonic with no airplane at all!

http://en.wikipedia.org/wiki/Joseph_Kittinger

Yeah, those shockwaves set-up a coanda effect at his feet and untied his bootlaces! Thus, destabilizing at around 97,000 feet...ya know, flailing boot-laces and all*...... :D


Did that french guy ever succeed in getting his 'supersonic' jump effort of the ground?


* jus' kiddin-round

First time Juke
02-21-2009, 04:33 AM
Yeah, those shockwaves set-up a coanda effect at his feet and untied his bootlaces! Thus, destabilizing at around 97,000 feet...ya know, flailing boot-laces and all*...... :D


Did that french guy ever succeed in getting his 'supersonic' jump effort of the ground?


* jus' kiddin-round

Yeah me too...

If he has plane propeller headgear ( seen ofter in sports events )

...would he then be first propeller plane to reach MACH 1.0 ?

:eek13:

RB77fan
02-22-2009, 03:11 PM
"Chris is right..there is lotsa stress on the blades. Since the tips of the blades are what counts...why does both LF 2100 and MB I have so thin end section in the fuse ?"...what about the blades on that biplane that look like stretched dimonds

First time Juke
02-23-2009, 01:58 AM
Chris,

That prop thing is very crucial as you have rightfully pointed out.

I was just figuring out that my MAX III ( in my blog ) would need only 35% power for take off if I could use the right pitch and create optimal thrust..but since the prop has to be optimised ( fixed as it is ) for higher cruise speed ( some 165 mph ) I need over 90% power for take off. That kinda fixed prop windmilling in emergency causes lotsa twist that has to be compensated by some x-tra speed to get some aileron forces into play and preventing anything nasty from happening.

Prop itself is interesting..as are the wings.

Juke

TOR_DP
02-23-2009, 06:14 PM
I'd say the Merlin to too wimpy.

The Griffon will give 3-4000 ponies at a slight weight penalty.

The salami slicer prop wouldn't be my choice... I'd try a swept blade composite with 5-7 blades.

Skyracer
02-23-2009, 09:50 PM
There is a very interesting article in the current "EAA Experimenter" about prop efficiencies (dispells a whole lotta prop myths).

First time Juke
02-24-2009, 02:26 AM
AASI's JetCruzer 500 ( 350 + mph 6 seater ) has 5 blades and looks pretty cool.

http://www.pilotfriend.com/acft_manu/images/jetcruzer500.gif

Skyracer
02-24-2009, 08:04 AM
There is a very interesting article in the current "EAA Experimenter" about prop efficiencies (dispells a whole lotta prop myths).Here's the link: http://www.eaa.org/experimenter/articles/2009-02_elippse.asp

First time Juke
02-24-2009, 08:57 AM
Here an insert:

Testing of the fixed-pitch, three-blade ELIPPSE prop on my Lancair shows that it is performing at 82 percent efficiency in a climb at 105 mph IAS and at least 90 percent efficiency in cruise at 200 mph TAS. Also, multi-blade, fixed-pitch propellers with correct aerodynamic shape where the blades enter the spinner have as good a cruise efficiency as a two-blade propeller, but will have better static thrust and climb performance. And because a multi-blade propeller can be made smaller in diameter than a two-blade and still pump as much mass flow, it will be quieter because of the reduced tip speed at a given rpm. Tom Aberle’s “Phantom” Reno biplane qualified at 221 mph with its 64-inch two-blade prop in 2003, 241 mph with its 59-inch diameter three-blade propeller in 2004 at 250 rpm less than in 2003, and 251 mph with its 59-inch diameter four-blade propeller in 2007 at the 2003 rpm. Many commented on how quiet his propeller was as he flew by on the home course, where his noise was mainly from the engine exhaust. This in contrast to the T-6-like scream of the other racers!

That is remarkable.

Reno_Steve
02-24-2009, 08:53 PM
I thought the normal restricting factors on a race plane prop were the length of the under-carriage and trying to keep the prop tips sub sonic.

Small high revving props are not very good at slow speeds and give very low thrust for the HP.

At high speed large fixed pitch props just are not pushing the air back fast enough, for a prop that can be turned by the engine at slow speed.

I know we are talking about supersonic flight so we will have to make compromises but I think using a fixed pitch prop is going to be rather a handicap.

RB77fan
02-26-2009, 09:59 PM
see thats what i mean look at the blades on that puller ....would thouse work:dunno:

First time Juke
02-27-2009, 02:22 AM
I know we are talking about supersonic flight so we will have to make compromises but I think using a fixed pitch prop is going to be rather a handicap.


I just talked to an retired FAF chief testpilot about 45 minutes on the phone about pusher prop planes and going beyond mach 1.0 ( and 2.05 like he has ) in general and attempts to do it with a kitplane etc.

Summa summarum: It would be a great risk with limited resources to trying go mach 1.0 even with a homemade jet ( we didn't even discuss the propability to do it with a prop plane ).

Instead we discussed if a pusher prop with manually operated lite retracts and 60-70 kg/m2 wingloading would be safe for a regular ultralite flyer to fly at 150+ mph speeds with a 22 hp powerplant.

All the risks and possibilies seem to lie in following:

1. prop
2. prop
3. wingloading
4. cooling

Why the prop twice.

1.Prop will collect all the debris and rocks and ice etc from fuse ( this has to be known to a pilot...and gained advance greater than the risk taken on each flite ).
2.Prop would have to be such that it works both in high speed and at take off adequately
3. 120 kg/m2 loading like in VmaxProbe is killer he said..60-70 kg/m2 sounded more suitable ( he said he would have stayed far away from VmaxProbe if he was asked to fly it ).
4. Cooling is a nuisance to handle in pushers (I also recall a BD-5 aluminum block Mazda engine quiting at take off..not good ).

So I guess not in our lifetime will the prop plane go supersonic ( how could it ? ) not even Tom's biplane on steroids .:):rolleyes:

These kinda gentlemen like Skip Holm and mr. Penney here and my friend here mr. Laukkanen ( and many others ) are the best choice of advise for any designer buider since their expertise will quide you through all trivial mistakes that can lie ahead and save years in building a flying prototype. In fact mr.Laukkanen was able to fix several errors in my design just by what he heard through from my description of the kite I have been designing before actually even seeing it. I'd call that valuable experience and I have no doubt that he wasn't right...I just sat by my computer and started redesigning it and voila several hours later I was back on the right track again...and being pretty sure about it.

RB77fan
02-27-2009, 07:07 AM
couldnt u do it in a dive with a pusher...i heard rumors on the military channel that a puller did it in a dive:dunno::dunno:

First time Juke
02-28-2009, 08:51 AM
Of course you could in a dive...with a prop that is pitched like the Orion prop on Rare Bear @ 520 mph. This would require an airframe that is thoroughly tested in a windtunnel and aviation engineers calculated thousands of equations and structural engineers tested the air frame with dozens of prototypes to make sure it can withstand the stress at mach 1.0 at specified altitude. Why bother when jet can do it easier ?

Kahuna
03-01-2009, 09:04 AM
The McDonnell XF-88 B "Voodoo" did M 1,12 in a dive !
Quote from Wikipedia:
The first prototype was modified to XF-88B standard, with a nose-mounted Allison T38 turboprop engine added to the two existing turbojets. This was used for flight testing through 1956, and achieved speeds slightly exceeding Mach 1.0,[2] the first propeller-equipped aircraft to do so.

Willy :bullhorn:

First time Juke
03-01-2009, 02:31 PM
The McDonnell XF-88 B "Voodoo" did M 1,12 in a dive !
Quote from Wikipedia:
The first prototype was modified to XF-88B standard, with a nose-mounted Allison T38 turboprop engine added to the two existing turbojets. This was used for flight testing through 1956, and achieved speeds slightly exceeding Mach 1.0,[2] the first propeller-equipped aircraft to do so.

Willy :bullhorn:

Any idea of the drag coefficient of the XF-88 ?

http://www.aviastar.org/air/usa/mcdonnell_xf-88b.php

John Fitzpatrick was the pilot !

First time Juke
03-06-2009, 03:04 AM
Here's the link: http://www.eaa.org/experimenter/articles/2009-02_elippse.asp


I see another advantage in this:

In a pusher prop design you have a great change to loose piece of a prop.

If you have 7-9 blades in a fan formed like ellipse prop the mass of that damaged prop tip will affect less dramatically in the normally life threatening situation in a larger two blader prop.

See what I mean ?

:cool:

First time Juke
03-10-2009, 03:13 AM
Ok folks !

After 16 months of research and designing on paper here it is a first relatively cheap to build ac that can "easily" brake the sound barrier with piston engines.

Everything about the plane is anything but cheap and "eazy" has to be taken with several grains of salt.

Plane would utilize ground effect to overcome drag and friction of the gear at take off. Slick looking ac if powered with 2 x 22 hp 2-stroke UAV engines would have almost "wingloading" of an ultra and go 300 mph with 20% of nitrous and special fans.

Heavier version to reach buffeting speeds and going beyond them would have to be partially titanium and carbon made and powered with yet nonexisting but in theory working DYNA CAM engines of 200 hp each and 29 kg weight..added radiators and speedy demand of fuel would make the operating time of the plane to be 5-6 minutes at full power. This would also need the redesign of the foils, wings could also be even smaller etc.

Funny how it looks a bit like F-15 Eagle or Su-27 Flanker !?:rolleyes:


rgds,

Juke

:beerchug:

First time Juke
03-19-2009, 06:49 AM
here is a good study on a racer design;

http://aero-comlab.stanford.edu/Papers/AIAA-2000-4341-839.pdf

First time Juke
04-08-2009, 05:13 AM
Here's the link: http://www.eaa.org/experimenter/articles/2009-02_elippse.asp

I see that LF 2100 performed better with 4 blader also than 3 blader.

How about this...pros and cons ?

First time Juke
04-20-2009, 08:55 AM
Could subs provide the answer for aviation prop technology ?

Kahuna
04-20-2009, 10:27 AM
......something like this ? Pontresina design by Luigi Colani !:deal:

Leo
04-20-2009, 10:43 AM
I once designed a "propeller" for a friend. It was a twisted flat plate to be towed behind his sailboat, attached by a fine cable to a generator. I first tried using what I had learned about aerodynamics and found that tho both are fluids, there was little correlation in practice. Predicting it's shape and effects ended up being a WAG followed by experimentaion. Of course this was before home computers...

First time Juke
04-20-2009, 11:17 AM
......something like this ? Pontresina design by Luigi Colani !:deal:


Right:

http://www.rc-network.de/upload/1063349843.jpg

:rolleyes:

Leo
04-20-2009, 11:58 AM
A delta-winged MachBuster! Sweet!

First time Juke
04-23-2009, 07:02 AM
How about this; http://www.flug-revue.rotor.com/FRHeft7X/FRHeft76/FRH7605/FR7605d.htm

First time Juke
05-18-2009, 03:30 AM
Like said before the only way to get closer to mach one would be a pusher with state of the art aerodynamics and an ideal prop in it.

I am becoming very sceptical since:

Cirrus VK30
Bede-5B
VMaxProbe
LearFan 2100
Mach Buster

all these projects failed...

The main problem in all is the mid mounted engine cooling...+CG and stubby looks due to heavy engine ( mostly 4 strokes ) and prop weight.

If and only if these aerodynamical challenges and engine cooling is solved properly and convincingly without making the ac excessively heavy ( wingloading ) will a cool looking pusher ever become a winner and fullfill the potential that is buried in the concept.

Good luck for the next tryer. :thumbsup:

Seems that only Jerry Holcomb and Molton Taylor ever fully mastered this along with few experienced Bede-5 builders.

First time Juke
05-24-2009, 05:52 AM
One more approach to this matter.

Since Dart had 2 seats I tried to incorporate also more passergers to keep fuse in nice form and get some useful outa this as well.

So here is a six seater for a TSIO-550A but a double V-8 of 1600 hp could be doable if 3 passengers were left out ( 1 if one V-8 was used of 600 hp ).

I wonder how heavy it would become but unlimited eligible at least.

GeoffS
05-26-2009, 04:40 PM
Of course, you can reduce the length of the drive-shaft and help with some of the CG by going to a canard configuration.

Cheers,

Geoff S.

First time Juke
05-28-2009, 12:40 AM
The downside of the canards is the landing speed and lenghty landing run....am I correct ?

runnemrand
05-28-2009, 07:56 AM
I have designed a single seat canard in x-plane with the sole purpose of breaking the sound barrier. It worked. The power plant is from the company which builds highly modified aircraft engines similar to the one used in Thunder Mustangs. X-plane is generally regarded as a very accurate flight simulation routine.

First time Juke
06-01-2009, 04:44 AM
The air intake scoop underside of the R3-A5...above ( two seater ).



Here is the update to that R3-A5. CG more forward..tricycle added and rudder stab added.

GeoffS
06-01-2009, 03:20 PM
The downside of the canards is the landing speed and lenghty landing run....am I correct ?

I assume you're referring to the fact that most canards don't have flaps on the main wing because of the nose-down pitching moment their deployment causes. It can be managed with engineering (ex. the Beech Starship has flaps). OTOH, if you're trying for flat-out high performance then the disadvantages of not having flaps might be worth it (ex. I believe the conventional-configuration Nemesis NXT doesn't have flaps).

Cheers,

Geoff S.

First time Juke
06-02-2009, 12:40 AM
Geoff you are possibly right. I am after low weight and flaps would increase the weight by several kilos.
Harry Holcombs Perigee had Guyana 35 hp engine that is 70 lbs. Starrair 280 ccm of same output is 13.5 lbs.
OTOH the flaps in Max III would make landing on a really small airfields possible. Some folks here who fly Cozys etc. are having trouble finding long enough airfields.

How does one make plane safe enough for lightning bolts ?
http://www.recreationalflying.com.au/forum/commercial-news/36355-missing-plane-lightning-bolts-risk-modern-jets.html

First time Juke
06-02-2009, 05:28 AM
Read the Pusher pusher- story in Flying mag. It goes right into the point in tractor vs. pusher plane debate !

First time Juke
06-03-2009, 07:45 AM
I also think a highly efficient form will give benefit;

http://www.youtube.com/watch?v=WaQB16ZaNI4

Those do almost 400 mph without an engine at all.

Kahuna
06-03-2009, 08:26 AM
I also think a highly efficient form will give benefit;

http://www.youtube.com/watch?v=WaQB16ZaNI4

Those do almost 400 mph without an engine at all.

.....have a closer look at the today's F1 class in Reno and you´ll find many similarities to today's composite RC Gliders ! :deal:

Willy