Go Back  RCU Forums > RC Airplanes > Extreme Speed Prop Planes
Reload this Page >

.65 "sport speed" - the doodling has begun.

Notices
Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

.65 "sport speed" - the doodling has begun.

Old 01-14-2009, 01:09 AM
  #1  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default .65 "sport speed" - the doodling has begun.

I figger it's about time to get going on an easy building sport speed design for 10/11cc RIRE engines, since I seem to have acquired a couple that need homes.

This one's raison d'etre is to keep myself amused for a season while I get around to the job of carving a nice plug for a full GRP fuse. I'm thinking built-up ply fuselage with composite reinforcement where needed, and a molded cowl and turtledeck. That leaves the option of flying it Quickie style with the fun stuff hanging in the breeze of course, perhaps for engine familiarization. Only rudimentary design has gone into it so far; at this point it is 598 squares intended for an AUW of 5.5-6.0 pounds, which gives a wing loading in the lower 20's. Stab is 16.something % but with a long enough tail moment that I can go down a bit, that bit of figgerin' is next. Nothing radical here, except perhaps the intended engine choices.

MJD

p.s. the two lines on top of the turtledeck are the 11" and 12" points foorm the center of the cylinder, respectively. IOW the limits of where the fat point of the pipe will be.
Attached Thumbnails Click image for larger version

Name:	Wu61433.jpg
Views:	7
Size:	43.0 KB
ID:	1110545  
Old 01-14-2009, 02:39 PM
  #2  
rmenke
Senior Member
My Feedback: (13)
 
Join Date: Jun 2004
Location: Merced, Ca., CA
Posts: 2,118
Likes: 0
Received 0 Likes on 0 Posts
Default RE: The doodling has begun.


MJD:

Yea, I do love the way your mind works. For what its worth, you can widen the basic Q-500 moments, extend the tank and engine compartment to accommodate a 10 oz tank and Jett 60LX cowelled in, extend the tail the same total, design high wing, motor side mount and have one heck of a great flyer. My most recent experiment was basic Q-500 with streemlined nose to fit Jett 60 LX, crop wing to 40". Was fastest thing I have ever seen or flown, crashed as I flat lost it in a high speed pass along with 10-12 observers. Next one off was about the same length moments, widned tor a 10 oz tank and Q-500 composit full 52" wing. Result is a sport like flying bird that still will outrun the gangs racing Q-500s and have good long flight times. You end up doing most of your flying at less than 1/2 throttle, in the idle circut of the Jett, but still around 16,000 with around 8.75 X 7.5 apc prop. Like it so much I am in the process of downscaleing the design for the Jett 35. Have ordered some mini-air retracts, not here yet. I want this puppy to also carry retracts just for grins. If I cant get um in with the high wing, will be back to low or sholder wing, cut to 36". Last one that is still alive after 5 years was 40" and even at the excess weight of 5.5 lbs accummulated from years of repairs, the thing still landed easy and slow. Got retired as the overall weight slowed her down in the corners and the guys were catching me in a 10 lap race. In the 08 season, no one ever came out with anything to challange the Jett 60LX thingy, so the effort was counter-productive and club interest suffered. One of the upstart kids has publicly challenged the 60LX with a Magnum setup, nice kid who will not back off. Gotta respect that even though we have had 3 mid-airs with the T-34's in recent races. Every year he learns a little more and gets a little better as I get a year older. It will happen, I will applaud him, but like most of us personality flawed racers, rage all the way home and for several days, maby weeks. Naturally, then we seek revenge. Gonna have to pry that transmitter out of my cold dead hands. ENJOY
Old 01-14-2009, 03:00 PM
  #3  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: The doodling has begun.


ORIGINAL: rmenke


MJD:

Yea, I do love the way your mind works. For what its worth, you can widen the basic Q-500 moments, extend the tank and engine compartment to accommodate a 10 oz tank and Jett 60LX cowelled in, extend the tail the same total, design high wing, motor side mount and have one heck of a great flyer. ENJOY
Yeah, I looked at Quickies as a starting point, but decided it was just as easy to start with a clean piece of paper. If this flies well I guess I'll have to do the 85-90% version for RIRE small blocks eh?

MJD
Old 01-14-2009, 10:53 PM
  #4  
combatpigg
Senior Member
My Feedback: (3)
 
combatpigg's Avatar
 
Join Date: Nov 2003
Location: arlington, WA
Posts: 20,388
Received 26 Likes on 24 Posts
Default RE: .65 "sport speed" - the doodling has begun.

I think you're off to a good start MJD. I question plywood though, it'll make rounding the exterior corners more difficult. The overall design looks real good, it looks "doable" by anyone who's got a decent size table and a straight edge. Do you figure on glass and paint on the exterior?
Old 01-14-2009, 11:09 PM
  #5  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: combatpigg

I think you're off to a good start MJD. I question plywood though, it'll make rounding the exterior corners more difficult. The overall design looks real good, it looks "doable" by anyone who's got a decent size table and a straight edge. Do you figure on glass and paint on the exterior?

Yeah, that's the plan for the finish. I know the corners are an issue.. I have some thinking to do on the pros and cons. Any good ideas that float my way will be given due consideration too.. I am fine with accepting a few compromises on this bird, in order to knock down construction time and complexity - this is what it is about. Not major ones mind you, but hypothetically for example if I were to lose 4.3 mph due to sharper fuse corners but it was much easier to build, that would be okay. Once my mind clears up somewhat from the past few days of tax purgatory, I might be able to think and make decisions.

It should also look cool in - to use current motorcycle parlance - "naked" form, that is without any of the cowling if so desired.

And a slightly scaled down version for small block engines might be of particular appeal to some folks..

MJD
Old 01-15-2009, 12:10 AM
  #6  
freakingfast
Senior Member
My Feedback: (3)
 
Join Date: Jan 2005
Location: Mather, CA
Posts: 2,222
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .65 "sport speed" - the doodling has begun.

I like the idea, but I'd like to see it in a V tail version.
The main problem with most speed planes is the dang things like speed so much they won’t slow down for a landing.
Too slow and they get uncontrollable or drop out of the air. A bit too fast and it goes screaming off the end of the average length run way.
So many fast planes have wonderful flights only to end forever by those two reasons.
Some humongous flaps that you can pop mixed with down elevator would be great.
Old 01-15-2009, 12:50 AM
  #7  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: freakingfast

I like the idea, but I'd like to see it in a V tail version.
The main problem with most speed planes is the dang things like speed so much they won’t slow down for a landing.
Too slow and they get uncontrollable or drop out of the air. A bit too fast and it goes screaming off the end of the average length run way.
So many fast planes have wonderful flights only to end forever by those two reasons.
Some humongous flaps that you can pop mixed with down elevator would be great.
I just had two replies vaporize, and I'm falling asleep.. so I'll get back to this tomorrow. I'm thinking single center section flap, and how not to tear it off.

'Nite all..

MJD
Old 01-15-2009, 07:02 AM
  #8  
combatpigg
Senior Member
My Feedback: (3)
 
combatpigg's Avatar
 
Join Date: Nov 2003
Location: arlington, WA
Posts: 20,388
Received 26 Likes on 24 Posts
Default RE: .65 "sport speed" - the doodling has begun.

drag chute?
Old 01-15-2009, 08:05 AM
  #9  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: combatpigg

drag chute?
Are you psychic? Both my attempts at a reply last night mentioned drag chutes.. semi-seriously. As a rocket geek these things tend to come to mind. Wouldn't need much. Split rudder? Drag brakes? Spoilers?



FF: the intention from square one was to design as a V-tail, with conventional as an option. For this quick sketch I dropped in TLAR conventional surfaces, because I wanted to check out the looks that way at first and because I hadn't done any math on the V-tail dims yet. Besides, if someone else were to build one assuming it works, there are folks who have a preference one way or the other. Sure most die-hard go fast folks think V-tails are the bee's knees, but I think regular tails still show up in the winner's circles with some regularity don't they?

As it is shown, the wing is 598 squares, at the target weight of 5.5 - 6.0 pounds - a rough estimate of component weights crudely added together - wing loading sits between 21 and 23 ounces per sq ft. Sounds manageable to me.

MJD







Old 01-15-2009, 09:33 AM
  #10  
daven
My Feedback: (1)
 
Join Date: Dec 2001
Location: Waseca, MN
Posts: 8,456
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .65 "sport speed" - the doodling has begun.

I have tested quite a bit of v-tail sizes on Q500 style planes and on a 500 square inch wing, a v-tail at 75 total square inches (15% of the wing) is about right. I have gone a bit smaller, and much larger. Any smaller and I was starting to lose too much stability in the turns for how I like to fly, and any larger just added additional weight and drag with neglible stability benefits.

With a 598 square inch wing, I would start with a v-tail around 90 square inches or each half at roughly 4 1/2" x 10. Elevators surfaces of about 1" in width and 6" in length would be plenty.

A v-tail angle of 110-115 degrees is pretty standard on most competitive Q500 birds.

It has been many years since a conventional tailed Q500 plane has won at the highest levels of racing. Q40 planes are predominately conventional tailed, but there has been a couple recent V-tailed models that are starting to take notice. The biggest issue I have seen with the V-tailed Q40's has been the take off, they have looked pretty squirlly. Not sure if that has been taken care of, but that wouldn't be a concern to someone looking at straight line speed.

Looks like you have a fun project going.
Old 01-15-2009, 10:08 PM
  #11  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: daven

I have tested quite a bit of v-tail sizes on Q500 style planes and on a 500 square inch wing, a v-tail at 75 total square inches (15% of the wing) is about right. I have gone a bit smaller, and much larger. Any smaller and I was starting to lose too much stability in the turns for how I like to fly, and any larger just added additional weight and drag with neglible stability benefits.

With a 598 square inch wing, I would start with a v-tail around 90 square inches or each half at roughly 4 1/2" x 10. Elevators surfaces of about 1" in width and 6" in length would be plenty.

A v-tail angle of 110-115 degrees is pretty standard on most competitive Q500 birds.

It has been many years since a conventional tailed Q500 plane has won at the highest levels of racing. Q40 planes are predominately conventional tailed, but there has been a couple recent V-tailed models that are starting to take notice. The biggest issue I have seen with the V-tailed Q40's has been the take off, they have looked pretty squirlly. Not sure if that has been taken care of, but that wouldn't be a concern to someone looking at straight line speed.

Looks like you have a fun project going.
Good info, thanks Dave. Didn't a junior win the Nats a couple of years ago with a regular tail aircraft? Yeah that's only one data point in the junior cat, I was just curious if I remembered correctly is all.

MJD
Old 01-16-2009, 06:50 AM
  #12  
C_Roundy
Senior Member
 
Join Date: Jan 2007
Location: Fairfield, CA
Posts: 219
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .65 "sport speed" - the doodling has begun.

In the 08 season, no one ever came out with anything to challange the Jett 60LX thingy, so the effort was counter-productive and club interest suffered.
Aww, shoot Ronald; no one came out to play?
Old 01-16-2009, 07:36 AM
  #13  
combatpigg
Senior Member
My Feedback: (3)
 
combatpigg's Avatar
 
Join Date: Nov 2003
Location: arlington, WA
Posts: 20,388
Received 26 Likes on 24 Posts
Default RE: .65 "sport speed" - the doodling has begun.

If Roger can hang in for another 10-20 years, advancements in science and medicine will be able to rebuild him piece by piece and he'll dominate the speed freak activity in that area for the next 100 years! [X(]
Old 01-16-2009, 08:07 AM
  #14  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: C_Roundy

In the 08 season, no one ever came out with anything to challange the Jett 60LX thingy, so the effort was counter-productive and club interest suffered.
Aww, shoot Ronald; no one came out to play?
It is strictly a personal challenge for now, these fringe activities get real thin around here. But there are a couple of nutbars in southern Ontario that might crawl out of the woodpile and dust off their moldering fan engines, given some form of incentive to come play. Toledo ain't that far from here as an example, if any fast freaks were to head there for some tomfoolery, I think it's a 5 hour drive for me - I'd do it in a heartbeat. Goes for 1/2A too. Upper NY state, NE Michigan, the upper half of Ohio are all within reason for something fun.

MJD
Old 01-16-2009, 09:28 AM
  #15  
daven
My Feedback: (1)
 
Join Date: Dec 2001
Location: Waseca, MN
Posts: 8,456
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .65 "sport speed" - the doodling has begun.

"Good info, thanks Dave. Didn't a junior win the Nats a couple of years ago with a regular tail aircraft? Yeah that's only one data point in the junior cat, I was just curious if I remembered correctly is all.

MJD"

It would have been more than a couple years ago, I believe you are thinking of Nick Maxwell, and that was 2001. Steven Baker may have won (Senior) with their conventional stabbed low wing, but that was more than 5 years ago also. The open class has been dominated by v-tailed aircraft since 2000'. Had some of the better pilots flown conventional tailed aircraft the results may have been different, but it was right about then that just about everyone converted to the V-tail and it took over as the standard in National competition.
Old 01-16-2009, 09:59 AM
  #16  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: daven
It would have been more than a couple years ago, I believe you are thinking of Nick Maxwell, and that was 2001. Steven Baker may have won (Senior) with their conventional stabbed low wing, but that was more than 5 years ago also. The open class has been dominated by v-tailed aircraft since 2000'. Had some of the better pilots flown conventional tailed aircraft the results may have been different, but it was right about then that just about everyone converted to the V-tail and it took over as the standard in National competition.
Brain cells are unreliable, temporary fleeting things. 2001, 2006, close enough..

I figured it was some sort of combination of the current standard being flown by good pilots, and the actual benefits of that standard itself.

On this aircraft I'd be tempted to tell folks just to use what they know and prefer. Dunno what the actual difference is but it wouldn't be any kind of show-stopper.

MJD
Old 01-16-2009, 10:47 AM
  #17  
daven
My Feedback: (1)
 
Join Date: Dec 2001
Location: Waseca, MN
Posts: 8,456
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .65 "sport speed" - the doodling has begun.

Your right, very minimal. The largest arguement I hear in favor of the V-tail is that their is less junctions between the tail and the fuse, hence less drag.

To people inexperienced building V-tails, they can be intimidating and a little bit of a learning process. I'm sure the speed of each would be very close and neglibly noticeable to just about everyone.

I think they just look cool
Old 01-16-2009, 11:15 AM
  #18  
Mike Connor
Senior Member
My Feedback: (5)
 
Mike Connor's Avatar
 
Join Date: Jan 2002
Location: Tulsa, OK
Posts: 2,025
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: daven

Your right, very minimal. The largest arguement I hear in favor of the V-tail is that their is less junctions between the tail and the fuse, hence less drag.

... I'm sure the speed of each would be very close and neglibly noticeable to just about everyone.

I think they just look cool
It seems you would have less drag going straight but more in turns. Heavy up elevator would also be like applying left and right rudder at the same time. But they do look cool.
Old 01-16-2009, 11:21 AM
  #19  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: daven

Your right, very minimal. The largest arguement I hear in favor of the V-tail is that their is less junctions between the tail and the fuse, hence less drag.

To people inexperienced building V-tails, they can be intimidating and a little bit of a learning process. I'm sure the speed of each would be very close and neglibly noticeable to just about everyone.

I think they just look cool
Well, yeah they do look cool. And I agree that they are foreign to some fliers.. and that counts for a lot. I would say that unless the V-tail option is nearly perfectly refined, the differences are small enough - if even tangible - that it may be more important for a pilot/racer to go with the style that they know and trust, so that there is no mental factor distracting their focus.

Like elliptical wings or many high performance airfoils at lower Rn, the theoretical advantages are destined to remain theoretical if they are not executed with a certain minimum level of precision. A narrow chord section near the tip of an elliptical wing that, under a magnifying glass, looks like the cross-section of a rough-hewn timber, is not good for much for example. But I would say it is easier to construct to the level required to realize the advantages of a V-tail than perhaps those of the two examples just mentioned.

Positive factors for V-tails - fewer fuselage junctions, and two sets of tip losses instead of three.

MJD
Old 01-16-2009, 11:22 AM
  #20  
HighPlains
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 4 Likes on 4 Posts
Default RE: .65 "sport speed" - the doodling has begun.

It is purely a myth that V-tail'ed models are any faster than a conventional tail. The first V-tail that I seen in a race was in Northern California in 1981. The rather well know racer of that airplane cheated with engine mods and spiked his fuel with a high nitro/oil mix. He explained his success as the attribute of the V-tail.
Old 01-16-2009, 02:25 PM
  #21  
HighPlains
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 4 Likes on 4 Posts
Default RE: .65 "sport speed" - the doodling has begun.

Like elliptical wings
It's not so much that elliptically shaped wing planforms are so efficient, but rather having an elliptical distribution of lift.
Old 01-16-2009, 04:01 PM
  #22  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.

ORIGINAL: HighPlains

Like elliptical wings
It's not so much that elliptically shaped wing planforms are so efficient, but rather having an elliptical distribution of lift.
Okay, I'll try this then:

"Like elliptical or other wing planforms designed to produce an elliptical lift distribution, for example a semi-ellipse, or many high performance airfoils at lower Rn,.." (Edit: the airfoil part being a separate thought and nothing to do with ellipses but I wrote that a bit unclearly)

The point being that an elliptical wing, being an ellipse and undoubtedly chosen by the designer because of its favorable elliptical lift distribution, will only be advantageous if attention is paid to details such as the local cross section at difficult to reproduce areas such as the wing tips where the chord diminishes to zero. Otherwise, the performance errors induced by the local discrepancies that inevitably result when difficult to reproduce articles are fabricated with anything less than the equipment needed to do the job with sufficient accuracy, such as CNC machines, may cumulatively be of sufficient magnitude to overshadow any benefits that would otherwise be evident.

[sm=spinnyeyes.gif]

Darnit, I stopped housecleaning again..

MJD

p.s. I'm just having fun..
Old 01-16-2009, 06:37 PM
  #23  
combatpigg
Senior Member
My Feedback: (3)
 
combatpigg's Avatar
 
Join Date: Nov 2003
Location: arlington, WA
Posts: 20,388
Received 26 Likes on 24 Posts
Default RE: .65 "sport speed" - the doodling has begun.

Some of the elaborate features have to be executed perfectly.....to the Nth degree, to realize any benefit. OTOH, if you keep things simple and are capable of building straight, the returns on your time and efforts will most likely be better.

Old 01-16-2009, 07:54 PM
  #24  
MJD
Thread Starter
My Feedback: (1)
 
MJD's Avatar
 
Join Date: May 2003
Location: Orangeville, ON, CANADA
Posts: 8,658
Likes: 0
Received 2 Likes on 2 Posts
Default RE: .65 "sport speed" - the doodling has begun.


ORIGINAL: combatpigg

Some of the elaborate features have to be executed perfectly.....to the Nth degree, to realize any benefit. OTOH, if you keep things simple and are capable of building straight, the returns on your time and efforts will most likely be better.
A good example in this particular case is the airfoil, it needs to be pretty accurate to get all the low drag benefits at speed. So we'll see how that goes, I'm chewing on ideas somewhere between regular fabrication/building techniques and CNC molds.

MJD
Old 01-16-2009, 08:17 PM
  #25  
HighPlains
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 4 Likes on 4 Posts
Default RE: .65 "sport speed" - the doodling has begun.

Absolute accuracy of the airfoil is not all that critical. Avoiding flat spots and waves is. Front third to 1/2 of the wing surface important. Behind that, not so much. Last third of most airfoils completely turbulent at the low speeds/Reynolds numbers that model fly at. Knowing how to sand, and observe shadows from point source of light all that is required. Leading edge radius and location very critical over the span of the wing. Make and use a template.

You don't have to have an elliptical wing planform to achieve an elliptical lift distribution - at one angle of attack. Otherwise, it does help.

The classic elliptical wing planform is not the lowest drag configuration. The Crescent shaped wing drag is about 3% better. This has the elliptical area distribution, but helps reduce tip vortexes. A good approximation was done on the Nemesis.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.