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Author Topic: A question about small stunters  (Read 8825 times)

Offline John Miller

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A question about small stunters
« on: June 14, 2009, 09:06:10 AM »
Here's a question.

Is the stunt world ready to accept a small, 380 sq inch Precision Stunter?

I've been working on designing, and modifying, just such a machine.

I'm figuring on using a strong .15 engine turning a 9X4 prop. Span is about 44". Design weight is ~25 to 32 oz's. I think 55 to 60 foot line legnth will be the ticket.

There should be plenty of room in the manuevers to really establish the straight lines in the square tricks. It should also give the illusion of blinding small radius corners.

I'm going to try and post a jpeg of the drawing so far. Ok, that worked. As you can see, it's heavily influenced by the latest Pathfinder L.E., but differs in some areas. The wing is based on Dave Gierkes' All American Eagle, and is in reality, a modified I-Beam. The rib percentage thickness, is a little less, and it's a tail dragger.

« Last Edit: June 17, 2009, 05:45:06 PM by John Miller »
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Offline Robert McHam

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Re: A question abpout small stunters
« Reply #1 on: June 14, 2009, 10:11:37 AM »
I like this idea a great deal.
Something tells me that trying to swing a 9x4 prop on a .15, even a strong one is far to much. Course I am no expert on .15s.

As a related question, what are considered to be the strong runners in the .15 size these days?
I think I should add to this question that I am asking about stock .15s and not some mega tuned combat rig.

Robert
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Offline John Miller

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Re: A question abpout small stunters
« Reply #2 on: June 14, 2009, 10:30:41 AM »
Ty, Ty, Ty, a Barnstormer just wouldn't be right with flaps.... n1 LL~ H^^

Robert, a strong .15, even an fp or La, can swing a 9X4 effectivly with 20% nitro. That's what we found with the Pathfinder twins.

I am aware of at least 2 available, non-combat/speed, stock, .15's that would work great. OS's .15AX really put out the ponies for such a small displacement, but they are pricey. I'm currently testing out Magnum .15XLS, which appears to be a clone of the OS offering. I'm having the venturiis made, and expect to run them, (I have 2 of them) soon.

They are reasonably priced, and sometimes go on sale for 10 bucks less.  

http://www.hobbypeople.net/gallery/210605.asp#More
« Last Edit: June 14, 2009, 11:24:07 AM by John Miller »
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Offline Jim Pollock

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Re: A question abpout small stunters
« Reply #3 on: June 14, 2009, 04:57:59 PM »
John,

Barnstormer MK II has flaps!

Jim   ;D

Offline John Miller

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Re: A question abpout small stunters
« Reply #4 on: June 14, 2009, 06:48:15 PM »
Something deep inside me just can't accept a barnstormer with flaps. I may be becoming a curmudgeon. HB~>

As for a kit, I'm not sure. I'll have at least one laser cut so I can build it, and then see from there. If it flies, and presents, like I think it might, if the weight can be kept to a good wing loading, I may do the short kit thing then. H^^
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Offline Don Hutchinson AMA5402

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Re: A question about small stunters
« Reply #5 on: June 15, 2009, 12:30:57 PM »
A superb concept although you may find you would like a "bit more poke" up front. Actually about the same size as the Yates Madman which originally had  Orwick 64's and 73's for power. Today they fly real good on a 35 or 40. The Madman Bart K has had such good results with started out with a Magnum 25 in it but suffered from lack of guts.
Don.

Offline John Miller

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Re: A question about small stunters
« Reply #6 on: June 15, 2009, 01:34:11 PM »
Thanks for the info Don. You may be right. I think I'll set the mounts up so I can easily swap out engines if needed.

I'm basing my use of a strong .15 on the performance of the Pathfinder Twin which uses 2 OS .15fp's and 20% nitro, turning a pair of 9 X 4's at ~11,000 rpms, here at 4600 feet ASL. Norm Whittle used a pair of OS .15Ax's and got the same or better performance on 10% nitro, but the plane was lost last year.

At the Northwest regionals, flying Gordy's OS .15fp twin, he was able to complete the overhead eights, even though the outboard engine had quit part way through the manuever. he then went on to do the inside loop of the clover, but decided to bail after the first outside.

This was at sea level using 20% nitro, with a plane that is the same exact size as the regular Pathfinder, 620 sq inches.

This performance leads me to believe that these modern BB .15's have a whole lot more power than we usually ascribe to them, but, like I said, I'll set the mounts up for easy engine swaps, just in case.

I'm anxious to see how such a smaller design, with good power, will present dueing the pattern.

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Offline Randy Powell

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Re: A question about small stunters
« Reply #7 on: June 15, 2009, 01:49:16 PM »
John,

I think I'd go with a .25
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Offline John Miller

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Re: A question about small stunters
« Reply #8 on: June 15, 2009, 02:52:25 PM »
John,

I think I'd go with a .25

So, no spirit of adventure Randy? LL~ LL~ LL~ :!
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Offline John Miller

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Re: A question about small stunters
« Reply #9 on: June 15, 2009, 02:54:29 PM »
HI John. Um, I have this great Fox .15 you can use. I don't go fishing anymore. LL~ LL~ H^^I'll even throw in a white nylon prop. D>K

Ok, throw, or hurl it over here.... LL~ LL~ LL~

Actually guys, I can take the ribbing. Remember, it might actually work... :! H^^
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Offline Randy Powell

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Re: A question about small stunters
« Reply #10 on: June 15, 2009, 03:05:59 PM »
>>So, no spirit of adventure Randy?<<

If I wanted adventure, I'd put a .65 in it.
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Offline John Miller

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Re: A question about small stunters
« Reply #11 on: June 15, 2009, 03:31:00 PM »
>>So, no spirit of adventure Randy?<<

If I wanted adventure, I'd put a .65 in it.

 ~^Kewl idea Randy. I'd have to make the landing gear a lot longer though HB~> HB~> LL~ LL~ LL~ ROFLMAO
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Offline Mark Scarborough

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Re: A question about small stunters
« Reply #12 on: June 15, 2009, 05:22:15 PM »
John,
make it an X wing,, with the vertical wing to mount a center line wheel on,, and tip outriggers,, then think of the overhead performance! and line tension!
actually a cool little concept, just worried about flying in turbulance and wind?
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Offline Robert McHam

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Re: A question about small stunters
« Reply #13 on: June 15, 2009, 05:46:38 PM »
John, I just have to ask... What will the name of this ship be?

Robert
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Offline John Miller

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Re: A question about small stunters
« Reply #14 on: June 15, 2009, 06:15:33 PM »
Sorry Mark, when I think Of X wings, I see star Wars fighters. I actually once built and flew an RC design by Bill Evans that was tailess, and had an X wing. Flew pretty good too.

Robert, Due to the heavy influence from Gordan's Pathfinder L.E., I'm disposed to call it Lil' Elle. I don't know if that'll be the final name though.
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Offline Jim Thomerson

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Re: A question about small stunters
« Reply #15 on: June 16, 2009, 09:17:35 AM »
If you want a classic airplane for a strong 15, the Stoker Cougar is a very nice looking and flying airplane.  it is an Aeromodeller plan.   

Offline john e. holliday

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Re: A question about small stunters
« Reply #16 on: June 16, 2009, 09:52:09 AM »
Big John,  I like the idea.  That is one of the reasons I built Bob Zambelli's version of a Cardinal called "Cardinette".  Haven't flown it yet.  May I have permission to down load the plans?  DOC Holliday
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Offline Jim Thomerson

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Re: A question about small stunters
« Reply #17 on: June 16, 2009, 12:24:04 PM »
I've thought about this a little more.  I have had a lot of experience flying 15 size stunt airplanes.  Dmeco Sport Wings, A-B All American, Cougar, A-B Trixter Profile, #5 Easy, Mackey Profile, etc.  These are all a bit smaller than your airplane.  They have weighed in the 17 - 19 oz range.  With ST G20-15 diesel, I flew for a while with 9 x 4, which the diesel turns at @12,000. It was satisfactory.  Later I went to an 8 x 4 which moved the engine up the power curve (review says peak HP at 15,000) and think the engine is happier.  I flew on 55 to 57 ft lines, eye to eye.  No problem at Tuscon at 2500 ft.

So, I think 11,000 on a 9 x 4 would be disappointing, particularly at your altitude.  24 - 25 oz,  for your size airplane,sounds about right to me.  Also, I don't think you will be able to fly on long lines. 

Offline John Miller

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Re: A question about small stunters
« Reply #18 on: June 16, 2009, 02:29:59 PM »
I've thought about this a little more.  I have had a lot of experience flying 15 size stunt airplanes.  Dmeco Sport Wings, A-B All American, Cougar, A-B Trixter Profile, #5 Easy, Mackey Profile, etc.  These are all a bit smaller than your airplane.  They have weighed in the 17 - 19 oz range.  With ST G20-15 diesel, I flew for a while with 9 x 4, which the diesel turns at @12,000. It was satisfactory.  Later I went to an 8 x 4 which moved the engine up the power curve (review says peak HP at 15,000) and think the engine is happier.  I flew on 55 to 57 ft lines, eye to eye.  No problem at Tuscon at 2500 ft.

So, I think 11,000 on a 9 x 4 would be disappointing, particularly at your altitude.  24 - 25 oz,  for your size airplane,sounds about right to me.  Also, I don't think you will be able to fly on long lines.  

Thank you for this helpful information. It's solid food for thought, based on your experiences. Magnum also recommends an 8X4 prop. I also agree with the prop proposal. As for weight, I think I can keep it light by careful selection of wood and sizes during construction.

Weight is another thing though. I've been taught that comparing to a known stunter usually works out OK. Since here where I live, the altitude is high, we relate to a 38 ounce Nobler as a standard to shoot for.

A Nobler, at 38 oz's gives a loading at just under 14 sq inches per ounce. I like to use the square inches/weight instead of the weight/square inches (times) 144 (the number of square inches in a square foot) which in the case of the above Nobler, is 10.325 oz's per sq. ft, but, I'll use the latter in this case.

The lil' Elle, would be slightly less than 9.5 ounces per square ft at a total weight of 25 oz's, making the wing loading better than that very light Nobler above.

So, a wing loading matching the light Nobler would be achieved with 27 1/4 ounces of total weight with the new design.

Nowadays, every where else, a normal Nobler is figured to be really good if the total weight is 42 oz's, which makes a wing loading of just under 11 1/2 oz's per sq ft.

So, the weight that matches for this new design is slightly more than 30 oz's.

Of course the newer airfoil should be able to carry more of a loading than the thinner Nobler AF, so I feel that somewhere between 25 and a max of 32 ounces should work out, of course lighter should be better.

The line legnth as you've suggested, will likely be under 60 feet.

It's going to be fun, I think, and thank you for your interest and helpful contributions.
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Offline John Miller

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Re: A question about small stunters
« Reply #19 on: June 16, 2009, 03:17:41 PM »
I was thinking some more about your experiences Jim.

Tell me please what are your experiences flying the pattern with these smaller planes?

How do they present in the pattern?

Do they lock in and fly with out looking like they are being bounced around with every vagury of wind or turbulence?

Can you establish a good straight line in the square manuevers?

Do the square corners give the impressions of being very small radii?

These are some of the things I'm hoping to see with this exercise.

Thanks again for your interest.
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Offline Jim Thomerson

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Re: A question about small stunters
« Reply #20 on: June 16, 2009, 03:25:50 PM »
I think there is a scale effect; the smaller the airfoil the lower the Renolds number, or some such, which means that the smaller the wing the lower the satisfactory wing loading.  There is also a scale effect in that the small airplane can be built proportionately much lighter than the big airplane and still have adequate structural strength.  Your plan looks good in that there seems to be little excess structure.  

Offline Jim Thomerson

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Re: A question about small stunters
« Reply #21 on: June 16, 2009, 03:42:45 PM »
I think you have to fly a small airplane with a little faster lap time than a big airplane.  This is in part because of line tension and in part to make the wing more efficient, perhaps.  I like to be around 4.5 seconds. Not bouncing around in the wind is related to having the right power (and design, of course).  I think you can have a small airplane present very well, look very sharp on corners and hold level lines.  I use 4 inch bellcranks and minimal deflection on the flaps and elevator, 20 - 25 degrees each way, and a more forward CG than most. I used to fly a lot of 1/2A stunt.  In practice, I would fly a couple of patterns with the 1/2A and then get the Fox 35 airplane out.  It was so slow and easy to fly after flying the 1/2A! Z@@ZZZ

Offline Jim Pollock

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Re: A question about small stunters
« Reply #22 on: June 17, 2009, 02:18:39 PM »
I had really rather see it for a 19-20, 25 sized plane with about 420 Sq In., but that's just my preference. 

Jim Pollock   D>K

Offline Leo Mehl

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Re: A question about small stunters
« Reply #23 on: June 17, 2009, 05:34:22 PM »
Here's a question.

Is the stunt world ready to accept a small, 380 sq inch Precision Stunter?

I've been working on designing, and modifying, just such a machine.

I'm figuring on using a strong .15 engine turning a 9X4 prop. Span is about 48". Design weight is ~30 to 35 oz's. I think 55 to 60 foot line legnth will be the ticket.

There should be plenty of room in the manuevers to really establish the straight lines in the square tricks. It should also give the illusion of blinding small radius corners.

I'm going to try and post a jpeg of the drawing so far. Ok, that worked. As you can see, it's heavily influenced by the latest Pathfinder L.E., but differs in some areas. The wing is based on Dave Gierkes' All American Eagle, and is in reality, a modified I-Beam. The rib percentage thickness, is a little less, and it's a tail dragger.


John, I have just downsized My Arctic fox to fit a LA25 engine. About 390 square inches wing area. 42' wing span and 33 inch length. I think it will fly grat. When I had plans done for this plane I had a set reducesed to a 38" wing span and I am powering it with a Fox 25. The sixtys version and it does the whole pattern quite well but have alwas felt it needed More wing area so now I will probably power it with an Enya 25 or 30. My solution to a smaller plane. HB~>

Offline John Miller

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Re: A question about small stunters
« Reply #24 on: June 17, 2009, 05:53:26 PM »
Hi Leo

Sounds good. I think your first one was too small for the engine's power. I'm glad you feel it flew well, but I think you're going the right direction.

The plane I'm working on could mount a .20 or .25, but I believe the .15 I'm planning on using will be plenty of power for it, based on experiences with the PF Twin. You remember seeing it fly at Pasco don't you?

Anyway, I'll be watching for your reports on the new "larger, small" Artic Fox.

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Offline Leo Mehl

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Re: A question about small stunters
« Reply #25 on: June 17, 2009, 07:57:04 PM »
It has been my experence that the small plane flies well and can be trimed to fly like it's big brother. I think some designs present themselves as being bigger. With the Arctic Fox it is a case for it being a cute plane that flies well. I have found that a smaller plane with more power can fly a really good pattern. Leo HB~> HB~> HB~> H^^

Offline jim gilmore

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Re: A question about small stunters
« Reply #26 on: June 18, 2009, 12:47:56 PM »
I would think the biggest problem with small models is the same problem that created the corsair fighter of wwII.
While you downsize the aircraft you want to up size the propeller but then the landing gear gets to be too short. especially for Grass. So you lengther the landing gear and it starts wanting to nose over too easy.

Offline John Miller

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Re: A question about small stunters
« Reply #27 on: June 18, 2009, 02:02:30 PM »
I would think the biggest problem with small models is the same problem that created the corsair fighter of wwII.
While you downsize the aircraft you want to up size the propeller but then the landing gear gets to be too short. especially for Grass. So you lengther the landing gear and it starts wanting to nose over too easy.

Hi Jim.

Though some of the reason for the inverted gull wing may have to do with preventing nose over, there's an even bigger reason for it.

As the engines became available with more and more horsepower, the props went from 2 blades to 3, to 4, and the width increased to help control the horsepower.

Eventually they had to start legnthening the props too, and this made for the need for taller gear to keep the prop out of the deck. Initially, the taller gear was not rugged enough to stand up to carrier landings, so the inverted gull wing was used so they could use shorter, stronger gear.


When the F8 Bearcat was built, it's landing gear was tall and spindly, but it was built with stronger materrials and could with stand the heavy jolt of carrier landings.

Nose over can be controlled to some extent, by the placement of the main wheels. For smoother surfaces, there's angle from the CG to the point where the wheels touch the ground that allow for great wheel landings with full control. Team racers use 14 degrees. For most stunt designs, 14 to 20 degrees will do a good job, with the higher angles having better performance on rougher surfaces. 24 degrees plus is for rough fields, but tend to bounce as the angle of the gear becomes steeper.

The Lit'l Elle has it's main gear set at 19 degrees, and should do very good on hard surfaces, and reasonably well on rougher surfaces.

I'm still not totally sure that the engine I'm planning on using will be the best for it, but I'm figuring that engines up to .25's can be mounted. If I need more wing area I can increase the rib spacing and go to a bit higher AR. . Of course, I'll have to incrrease the area of the stab-elevator if I dop that too.  H^^
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Offline PatRobinson

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Re: A question about small stunters
« Reply #28 on: June 26, 2009, 11:01:21 PM »
Hi John,
This a cool looking little plane with big plane looks! it just occured to me that using a tuned pipe setup would be both a powerful and  unique in this size airplane. I have seen 25 tuned pipe setups produce mucho power that hauled planes quite well so a 15 size setup should give you power flexibility while also keeping the engine weight down.

It might be an offbeat idea but it should work and it would be a surefire conversation starter at any flying field you took it too. A small plane with a dead reliable "big-engine" type of run should be truly fun.

In any event, this is just another idea to consider. I hope you have a ball with this smaller plane.

                                                                               Best Wishes,
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Offline John Miller

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Re: A question about small stunters
« Reply #29 on: June 27, 2009, 11:16:56 AM »
Hi John,
This a cool looking little plane with big plane looks! it just occured to me that using a tuned pipe setup would be both a powerful and  unique in this size airplane. I have seen 25 tuned pipe setups produce mucho power that hauled planes quite well so a 15 size setup should give you power flexibility while also keeping the engine weight down.

It might be an offbeat idea but it should work and it would be a surefire conversation starter at any flying field you took it too. A small plane with a dead reliable "big-engine" type of run should be truly fun.

In any event, this is just another idea to consider. I hope you have a ball with this smaller plane.

                                                                               Best Wishes,
                                                                                                 Pat Robinson 

Thanks for your thoiughts and well wishes.


 I agree that a piped setup would be a neat thing to have in this size range. Of course, it would be nice if there were good rear exhaust engines in these sizes.

The OS .25vf exists, and the Cox Conquest .15 also exists, but both are out of production, for all intents an purposes. It would be rather easy to increase the area, by increasing the rib spacing, thus legnthening the wing. If such is done, the area of the stab and elevator should also be increased, but that would be rather simple to do.

One could mount the engine at an angle of about 45 degrees and then the pipe wouild lie on the centerline of the plane, as Igor Berger does with his small plane.

This is all interesting, and food for future development, should the performance of the prototype should warrent further development. I'm hoping that running the side exhaust engines in the high rpm, low pitch mode, that the performance will be similar to running them  "on the pipe".
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Offline jim gilmore

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Re: A question about small stunters
« Reply #30 on: June 27, 2009, 01:03:55 PM »
Is there a photo of the above mentioned cougar ? I've searched and only see places to buy the plans but no clue what it looks like .

Offline John Miller

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Re: A question about small stunters
« Reply #31 on: June 27, 2009, 01:16:34 PM »
Is there a photo of the above mentioned cougar ? I've searched and only see places to buy the plans but no clue what it looks like .

Here's what I found on the Cougar by Stoker
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Offline jim gilmore

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Re: A question about small stunters
« Reply #32 on: June 27, 2009, 03:04:19 PM »
Thanks, at least I know know what it looks like. Not my type but I now know.

Offline John Miller

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Re: A question about small stunters
« Reply #33 on: June 29, 2009, 06:21:23 PM »
I had an idea, and just included it on the plans. I've included two additional rib spacing jigs, and calculated the extra spar legnth needed to increase the areas to either 400 or 428 sq. inches easily.

I also noted on the plans just how much longer the stab span had to be for each increase in area.

This should make it easier for the times when a larger engine is being used. H^^
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Offline Martin Quartim

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Re: A question about small stunters
« Reply #34 on: June 29, 2009, 10:56:53 PM »
Hi John,

Have you seen the AP .15 with rear exhaust?  take a look at www.himodel.com  Been thinking about getting one of those, but not sure if they are any good.

Let us know the weight of the Magnun .15 with venturi and w/o muffler.

I'll definitely want to build one once plans are available, or better yet a kit.

The landing gear design gave it a special character, and it would be cool if it had anhedral.


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steven yampolsky

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Re: A question about small stunters
« Reply #35 on: July 01, 2009, 08:08:18 PM »
Here's a question.

Is the stunt world ready to accept a small, 380 sq inch Precision Stunter?

I've been working on designing, and modifying, just such a machine.


Being able to read Russian, gives me an opportunity to browse stunt forums from the other side of the globe. A top russian stunt flier, a many times national champion and Russian team member at the WC, decided to develop a serious stunt model for a .15 size engine. He built several prototype until he found one that worked extremely well. He took the model to one of the national-level competitions and asked a number of top fliers to fly the model and comment on its flying characteristics. All came back with good to excellent comments. attached is a photo of a model which he used to mark the dimensions, arms, ratios, etc. It's in metric(mm) so you'll need to convert it. The motor was a 2.5 MDS. Also not the location of the CG is 40mm fromthe leading edge.


EDIT: Grabbed the wrong picture. Posting proper ones
EDIT2: Adding missing dimensions: stab is 10mm thick, Wing is 44m thick.
« Last Edit: July 01, 2009, 08:26:24 PM by Steven Yampolsky »

Offline RandySmith

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Re: A question about small stunters
« Reply #36 on: July 01, 2009, 08:44:40 PM »
"" I agree that a piped setup would be a neat thing to have in this size range. Of course, it would be nice if there were good rear exhaust engines in these sizes.

The OS .25vf exists, and the Cox Conquest .15 also exists, but both are out of production, for all intents an purposes. It would be rather easy to increase the area, by increasing the rib spacing, thus legnthening the wing. If such is done, the area of the stab and elevator should also be increased, but that would be rather simple to do."""


For just about identical weight and size, you can have a new 32 ENYA RE  with pipe or  muffler

Randy

Offline John Miller

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Re: A question about small stunters
« Reply #37 on: July 02, 2009, 11:52:46 AM »
Being able to read Russian, gives me an opportunity to browse stunt forums from the other side of the globe. A top russian stunt flier, a many times national champion and Russian team member at the WC, decided to develop a serious stunt model for a .15 size engine. He built several prototype until he found one that worked extremely well. He took the model to one of the national-level competitions and asked a number of top fliers to fly the model and comment on its flying characteristics. All came back with good to excellent comments. attached is a photo of a model which he used to mark the dimensions, arms, ratios, etc. It's in metric(mm) so you'll need to convert it. The motor was a 2.5 MDS. Also not the location of the CG is 40mm fromthe leading edge.


EDIT: Grabbed the wrong picture. Posting proper ones
EDIT2: Adding missing dimensions: stab is 10mm thick, Wing is 44m thick.

Thanks for sharing this information Steven.


It appears that many of the sizes relate to being pretty similar to what I have. I'm estimating that the Russian design is slightly smaller though, at about 350 sq inches, and ~38 inch span.

The wing thickness is not quite as thick as mine, but perhaps the engine doesn't make as much power as the one I plan on using.

I know that Igor berger has a design he calls "The Tiny" that is in this size range as well.
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Offline John Miller

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Re: A question about small stunters
« Reply #38 on: July 02, 2009, 12:01:19 PM »
"" I agree that a piped setup would be a neat thing to have in this size range. Of course, it would be nice if there were good rear exhaust engines in these sizes.

The OS .25vf exists, and the Cox Conquest .15 also exists, but both are out of production, for all intents an purposes. It would be rather easy to increase the area, by increasing the rib spacing, thus legnthening the wing. If such is done, the area of the stab and elevator should also be increased, but that would be rather simple to do."""


For just about identical weight and size, you can have a new 32 ENYA RE  with pipe or  muffler

Randy



I'd forgotten about the Enya .32RE. Though I think this plane might be a little small for this engine, perhaps not so, if the weight is similar. I'm planning on using the Magnum .15XLS. It weighs 6.5 oz's with the rc carb, possibly a little less with a venturii.

I have made it easy to extend the wing some, so the largest wing area, at this time is 428 sq. inches. I believe that any more wing area, and the fuse may need to be legnthened. Perhaps the better solution would be to scale the original plan to about 500 or so sq. inches, and avoid gettin the AR too high.

I'll check out your site for the weight and price on this Enya.
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Offline jim gilmore

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Re: A question about small stunters
« Reply #39 on: July 02, 2009, 12:38:52 PM »
Looking at those plans has me wonder where small is ?
Are you implying the shark402 or a flitestreak would be a small stunter ?

Offline John Miller

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Re: A question about small stunters
« Reply #40 on: July 02, 2009, 01:46:54 PM »
That's a good question Jim.

Personally, I've always thought that .20 or less is a small stunter, so I guess the answer to your question, would be yes.

Back in the early days, the'd put a .60 in a 400 sq, inch plane. It would be considered a large plane. Of course, at that time they often flew the pattern at nearly 100 mph.

When Aldrich, Palmer, , Southwick and others started flying what were considered at the time, large "under powered" planes in the stunt event, they were first thought to be off the reservation.

I remember reading a report of the reaction to Palmers T'Bird's size, and small power plant when he made his visit to England. They were first, sure that it would have problems flying the pattern, and amazed at the performance when they saw him and it fly.

Designs have gotten larger until recently, when the trend seems to have turned to smaller planes with lots of power. Smaller planes seem to fit the hemishere we fly in better, but there are questions about how they will present, penetrate in less than ideal conditions. I think it's worth while to explore the option.
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steven yampolsky

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Re: A question about small stunters
« Reply #41 on: July 02, 2009, 01:50:33 PM »
The wing thickness is not quite as thick as mine, but perhaps the engine doesn't make as much power as the one I plan on using.

I think wing thickness is a lot less important for smaller designs so perhaps it shouldn't matter as much as the moments or wing/stab ratios.

Please note the control geometry: it's not 1:1 as in larger airframes. This goes along the same lines as Bill Werwage's control ratio research he's done with the Juno/Junar series.

Offline John Miller

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Re: A question about small stunters
« Reply #42 on: July 02, 2009, 01:52:10 PM »
Hi John,

Have you seen the AP .15 with rear exhaust?  take a look at www.himodel.com  Been thinking about getting one of those, but not sure if they are any good.

Let us know the weight of the Magnun .15 with venturi and w/o muffler.

I'll definitely want to build one once plans are available, or better yet a kit.

The landing gear design gave it a special character, and it would be cool if it had anhedral.


Martin

Martin, The Magnum .15XLS weighs 6.5 oz's with the muffler. I haven't weighed it with out the muffleer yet though. The plans are finished now, as far as I am going to do it, until a proto is built.

I've thought of anhedral too, I like the look it gives on my All American Eagle. It would look cool on this one too.
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Offline jim gilmore

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Re: A question about small stunters
« Reply #43 on: July 02, 2009, 02:19:34 PM »
I do not want to jack this thread but figured I'd add a little to my statement of small .
In the modeling world I have found defining size by the name to be very nonconforming.
Go over to a certain r/c site and you'll  see a whole forum on micro- but planes with 24"wingspan are not my Idea of micro. So to define small is at best just relative. The models in the 70"s grew and the original Gesike Nobler is small by the ships that took over.  So the question might be is the PA world ready to go back to smaller models ? or accept the performance of smaller models?
I personally think a smaller model has many advantages , though they may not necessarily be ones that stunt judges use when giving out points.

Offline John Miller

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Re: A question about small stunters
« Reply #44 on: July 02, 2009, 02:19:49 PM »
I think wing thickness is a lot less important for smaller designs so perhaps it shouldn't matter as much as the moments or wing/stab ratios.

Please note the control geometry: it's not 1:1 as in larger airframes. This goes along the same lines as Bill Werwage's control ratio research he's done with the Juno/Junar series.

I tend to agree, with a few reservations regarding wing thickness. Gordy used to fly a lot of Combat, and did a lot of experimental work with wings. Both span and thickness differences were compared, using speed, and maneuvering ability as the goal.

His Challenger series of combat planes were pretty good, good enough that the first Bladder Grabber was won with a Challenger.

He found that it took a really thick airfoil before it bothered the top speed of the plane, but, maneuverability went up. He also found that when most combat planes were about 36 inch span, his planes at 48 inches gave little up on speed, Instead, with the thicker airfoil, and lighter loading from the increased area, turned better, and maintained speed while maneuvering. He's told me that on occasions, he'd draw an opponent that was 10 mph faster on the level, but once they st arrted mixing it up, he'd keep his speed while the other fellow slowed down maneuvering. He'd have to be careful that he didn't over run his opponent in such cases.

His experiences tend to make me believe that within limits, more wing area, and thicker airfoils can be a good thing even with this size design.

I think the force arrangements are indeed important.

Interesting thing I noticed with the control geometry. The bellcrank has the control arm swept back at 15 degrees. It's an interesting set up.

1 to 1, ratio, isn't always the ideal as we both know. 1 to 1 works well when the plane is heavy, and the wing needs help creating enough lift for the extreme maneuvers, but can cause the nose to be "swoopy" in a lightly loaded design.

I'm concerned with Igor burgers statement that his "Tiny" doesn't handle the wind well though. All in all, I think this will be a fun and intersting project.

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Offline John Miller

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Re: A question about small stunters
« Reply #45 on: July 02, 2009, 02:40:46 PM »
I do not want to jack this thread but figured I'd add a little to my statement of small .
In the modeling world I have found defining size by the name to be very nonconforming.
Go over to a certain r/c site and you'll  see a whole forum on micro- but planes with 24"wingspan are not my Idea of micro. So to define small is at best just relative. The models in the 70"s grew and the original Gesike Nobler is small by the ships that took over.  So the question might be is the PA world ready to go back to smaller models ? or accept the performance of smaller models?
I personally think a smaller model has many advantages , though they may not necessarily be ones that stunt judges use when giving out points.


You make a good point Jim.

I do think PA is starting to go back to smaller designs, but with huge power. A large plane, when the winds blow gets hard to finese, when you're hanging onto a pull monster. The larger designs seem to be more affected by their size in the wind, basically becoming bigger kites.

I'm hoping that a smaller plane, that has been carefully sized and designed, will be easier to maintain control, and offer some benifits that will make it desirable for a lot of pilots.


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steven yampolsky

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Re: A question about small stunters
« Reply #46 on: July 02, 2009, 06:07:46 PM »
I'm concerned with Igor burgers statement that his "Tiny" doesn't handle the wind well though. All in all, I think this will be a fun and intersting project.

Keep us in the loop. I am most interested in how  it turns out. I myself am hoping to one day build a full-on .15 stunt ship and go win some contests. I even have a perfect engine for it: a diesel! Beating .75, 700sq in piped ship with a stinky 15 would be most fun.

Offline Dennis Adamisin

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Re: A question about small stunters
« Reply #47 on: July 02, 2009, 07:01:13 PM »

I have made it easy to extend the wing some, so the largest wing area, at this time is 428 sq. inches. I believe that any more wing area, and the fuse may need to be legnthened. Perhaps the better solution would be to scale the original plan to about 500 or so sq. inches, and avoid gettin the AR too high.


You can never be too rich, too thin or have too much AR  ;D

All seriousness aside, I'd point to the later comment about Gordon's success with long span combat models - efficient ift and good penetration are nice to have when you have limited power and are trying to penetrate in the wind.  I think it WOULD be good to to review some of the best ideas in combat models as they are roughly the same size as your target.  I too wil be watching this thread, got some ideas I'd like to try too...
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Offline John Miller

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Re: A question about small stunters
« Reply #48 on: July 03, 2009, 07:47:38 AM »
You can never be too rich, too thin or have too much AR  ;D

All seriousness aside, I'd point to the later comment about Gordon's success with long span combat models - efficient ift and good penetration are nice to have when you have limited power and are trying to penetrate in the wind.  I think it WOULD be good to to review some of the best ideas in combat models as they are roughly the same size as your target.  I too wil be watching this thread, got some ideas I'd like to try too...


Thanks dennis and Steve, for your interest, and comments.

I must admit, there are advatages to higher AR, and within reason, I like a slightly higher AR myself. My main worry in this case though is, that as simple a solution for more wing area, increasing the AR by increasing the wing span, is, I don't want to get too extreme. I've experienced the down falls of extreme AR in stunters, as, I'm sure, you have. (wow, that's some sentence structure, "Aint it?")

I once, I swear, got a three view of my Twin Flite Streak, while in level flight on a windy day. :o


The plans are basically finished now, and I may have shot myself in the foot, with the longer span options. It seems that to evaluate best, All three versions will have to be built. Arrrggggghhhhh.
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Online Steve Helmick

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Re: A question abpout small stunters
« Reply #49 on: July 04, 2009, 08:30:17 PM »
Ty, Ty, Ty, a Barnstormer just wouldn't be right with flaps.... n1 LL~ H^^

Robert, a strong .15, even an fp or La, can swing a 9X4 effectivly with 20% nitro. That's what we found with the Pathfinder twins.

I am aware of at least 2 available, non-combat/speed, stock, .15's that would work great. OS's .15AX really put out the ponies for such a small displacement, but they are pricey. I'm currently testing out Magnum .15XLS, which appears to be a clone of the OS offering. I'm having the venturiis made, and expect to run them, (I have 2 of them) soon.

They are reasonably priced, and sometimes go on sale for 10 bucks less.  

http://www.hobbypeople.net/gallery/210605.asp#More


The OS .15CV-A is the one that John is referring to. I have not found anything about piston/cylinder plating, but they seem to be switching over to "ABL". I have no idea what the "L" stands for. Don McCay is trying out the .15CV-A for 80 mph combat, and last I saw him, he said it worked well. Burdick/Rein tried the Magnum XLS .15 and got it working, but it barfed the crank. They're trying to use F2D airplanes with cheap engines for 80mph, and having good success at it.  n~ Steve
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