Pitts S1-S by EMHW
10-20-2015, 02:50 PM
#5426
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John,
Initially I guesstimated the weight was going to be 45lbs and did the math back then. At that time I realized it was not going to be heavy on the wings. Most guys, after a build, go up and start banging the sticks. I am not one of them, I like to check and double check, do anything and everything to ensure my work is up to par. Once I reach that point, of which I did at the event, that I feel it is all good then I will bang the sticks.
Like I told a friend in the beginning when we were comparing this Pitts to a Cub, it has the same wing area, nearly the same fuse length and tail area, and close enough on weight to say it's equal. But by design it's faster, more acro, and thanks to the owner it has four time's the power. Should be a great flyer!!
Initially I guesstimated the weight was going to be 45lbs and did the math back then. At that time I realized it was not going to be heavy on the wings. Most guys, after a build, go up and start banging the sticks. I am not one of them, I like to check and double check, do anything and everything to ensure my work is up to par. Once I reach that point, of which I did at the event, that I feel it is all good then I will bang the sticks.
Like I told a friend in the beginning when we were comparing this Pitts to a Cub, it has the same wing area, nearly the same fuse length and tail area, and close enough on weight to say it's equal. But by design it's faster, more acro, and thanks to the owner it has four time's the power. Should be a great flyer!!
Last edited by acerc; 10-20-2015 at 03:14 PM.
10-20-2015, 02:59 PM
#5427
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Well 46% of that would give you 15.7 oz / sq ft @ 7198 sq inches, or 49.9 sq ft wing area... its light as a feather in the air compare to my mono wing super cub, LoL... yours has a bit more weight on its legs when its on the ground though.
BTW, the full scale Pitts S1-S Wikipedia site says it has a 20 ft (240") wing span, and 125 sq ft wing area... aero-web site show it having 17.4 ft wing span, and 98.5 sq ft wing area... maybe there was a clip version, or the person that posted the spec's on wiki got it wrong... either way it would be safe to say your ol girl is hefty enough to take it at the wing loading she has.
John M,
BTW, the full scale Pitts S1-S Wikipedia site says it has a 20 ft (240") wing span, and 125 sq ft wing area... aero-web site show it having 17.4 ft wing span, and 98.5 sq ft wing area... maybe there was a clip version, or the person that posted the spec's on wiki got it wrong... either way it would be safe to say your ol girl is hefty enough to take it at the wing loading she has.
John M,
10-20-2015, 03:12 PM
#5428
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I found a discrepancy, my chord by tape is 15", the full scale adds up to 36" which means mine should be 16.5, there is the loss. I wonder why EMHW did that. I got to do some more digging, I can't very well say it's exact if it is off that much.
Last edited by acerc; 10-20-2015 at 03:14 PM.
10-20-2015, 04:05 PM
#5429
***EDIT***
The chord is more like 42%, but the wing span is 46%, interesting... I think what it boils down to, is what EMHW used as a reference design to base their model after; as you stated there are so many variations in the full scale spec's.
John M,
Last edited by John_M_; 10-20-2015 at 04:20 PM.
10-20-2015, 05:46 PM
#5430
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Hey Robert
All this wing loading discussion has got my curiosity up ....... just what is the wingspan and wing chord of your model? You've already listed the weight at 49 pounds 12.8 ounces.
It does appear to fly light on the wing and certainly looks good in the air.
Your color scheme has been growing on me. I wasn't a fan at first but the more I see it in the air the better it looks - very striking!
Cheers,
Art
All this wing loading discussion has got my curiosity up ....... just what is the wingspan and wing chord of your model? You've already listed the weight at 49 pounds 12.8 ounces.
It does appear to fly light on the wing and certainly looks good in the air.
Your color scheme has been growing on me. I wasn't a fan at first but the more I see it in the air the better it looks - very striking!
Cheers,
Art
10-20-2015, 05:53 PM
#5431
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R/C Art, glad to read that the color scheme is growing on you, I loved it the first day I saw it. So much so , that I had to do the color scheme for a Pitts in the Real flight simulator, it would COOl if Ace would post a pic. of them side by side in the same post, just for comparison...
10-20-2015, 07:17 PM
#5432
I've just been looking into Wing Cube Loading... its a means of calculating a comparison of the weight / wing area relationship between the full scale aircraft and the rc model... having the scale model with a similar Wing Cube Loading value as the full scale aircraft will give a good indication on its flying characteristics, flying more like the real aircraft.
Here's an simple online WCL calculator... Ace your Pitts has a WCL of 9.2, falls right in the category of General sport and scale aerobatics... the full scale pitts has a WCL value of 12 - 14 depending who's sitting in the cockpit (weight wise), 11.8 empty.
http://www.flyrc.com/wing-load-calculator/
***EDIT***
Another calculator
http://www.ef-uk.net/data/wcl.htm
Thought it was interesting comparison
John M,
Here's an simple online WCL calculator... Ace your Pitts has a WCL of 9.2, falls right in the category of General sport and scale aerobatics... the full scale pitts has a WCL value of 12 - 14 depending who's sitting in the cockpit (weight wise), 11.8 empty.
http://www.flyrc.com/wing-load-calculator/
***EDIT***
Another calculator
http://www.ef-uk.net/data/wcl.htm
Thought it was interesting comparison
John M,
Last edited by John_M_; 10-20-2015 at 07:31 PM.
10-20-2015, 08:03 PM
#5433
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The S1-S list a weight of 770 dry, that means mine should weigh 331. Some things just don't mathematically translate from full scale to modeling.
10-21-2015, 04:52 AM
#5434
Mike
10-21-2015, 06:13 AM
#5435
My Feedback: (3)
I have ran the numbers and came to the same conclusion, it is light in the sadle. I even went comparing it to a bunch of ARF's listed weight's. My point on "taking it easy because of the weight" is because EMHW list a weight of 33+lbs. I don't know if their + is up to 49lb 12.8oz, that is as stated earlier 16lb 12.8oz over 33lbs. After each flight I check thing's like the flying wire's for signs of overload stress and after six flight's have seen nothing. So from here on out it will be a "Fly it like I stole it" kind of Pitts, unless something in her tells me otherwise.
The only "taking it easy because of the weight" I know that means anything is the guy on the stick's comfort level. If the airframe is weak, it will fail when you least expect it and probably sometime after it has been stressed to or past its construction load. Since we aren't riding it there is no real way to tell the actual G loads we have imposed on it.
About 10 years ago I modified and flew a Gere Sport at 54 lbs but I had cheated and put a Quadra 50 in it and with 4 ailerons with individual servos it was good. It was great and wild fun right up until the battery supply wire failed. So once you figure out why the prop bolts failed and correct that (with a higher quality bolt?) enjoy your beautiful creation.
10-21-2015, 07:31 AM
#5438
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Ok guy's, it would appear most are taking my "weight thing" the wrong way so let me clarify. As with any of my build's I state right up front "I am not concerned about the weight". I build appropriately for the airframe regardless of what it adds or removes. What I am talking about with this Pitts is more a feel of the aircraft in the air, with it being 16+lbs beyond mfg'ers list I was worried that it would fly like a pig. Remember how before this past weekend I said it flies heavy as well as tail heavy. Now it feel's light in the saddle so to speak and much more balanced in the tail. As for the all up weight my only concern in regards to the airframe was the gear but they seem to handle the weight just fine. I kind of had that feeling anyway, but one never knows.
As with other's here, I also have seen where others have it just as heavy if not a bit more. However, seeing their over weight bird fly did not tell me how it flies, now I can say "it flies great"!
As with other's here, I also have seen where others have it just as heavy if not a bit more. However, seeing their over weight bird fly did not tell me how it flies, now I can say "it flies great"!
10-21-2015, 07:33 AM
#5439
Your 46% Pitts has a Wing Cube Loading value of 9.2... the full scale Pitts has a Wing Cube Loading value of 11.8 empty... so your 46% pitts is very close in relationship to the Wing Cube Loading values, model verse full scale, so your Wing Cube Loading value is a good indicator that it should fly very much like the real full scale Pitts... its all good
The WCL of a model should ideally be the same as that of it's full-size equivalent if scale flight performance is to be achieved.
Read here for a more in depth explanation of Wing Cube Loading
http://www.theampeer.org/M1-outrunne...unners.htm#CWL
John M,
10-21-2015, 07:34 AM
#5440
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Jim, the prop bolt's failed because I trusted a standard class 8 bolt instead of waiting for a order of class 12.9. The really stupid part is it only takes two days for delivery.
10-21-2015, 07:36 AM
#5441
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You are correct... but that's not what Wing Cube Loading means...."Wing Cube Loading" is the relationship of the weight of the model verses to the wing area of the model... the ideal "Wing Cube Loading" value for a model aircraft to get similar flight characteristic of the FULL scale aircraft, is to have as close a Wing Cube Loading value compared to the real FULL scale aircraft... so you run the numbers of the model i.e, weight / wing area you get the Wing Cube Loading value... then you run the numbers of the full scale aircraft, weight / wing area and get its Wing Cube Loading value... then you compare the two values, the closer the models Wing Cube Loading value is to the full scale aircraft's Wing Cube Loading value, the better indication that the model will fly more like the full scale aircraft.
Your 46% Pitts has a Wing Cube Loading value of 9.2... the full scale Pitts has a Wing Cube Loading value of 11.8 empty... so your 46% pitts is very close in relationship to the Wing Cube Loading values, model verse full scale, so your Wing Cube Loading value is a good indicator that it should fly very much like the real full scale Pitts... its all good
Read here for a more in depth explanation of Wing Cube Loading
http://www.theampeer.org/M1-outrunne...unners.htm#CWL
John M,
Your 46% Pitts has a Wing Cube Loading value of 9.2... the full scale Pitts has a Wing Cube Loading value of 11.8 empty... so your 46% pitts is very close in relationship to the Wing Cube Loading values, model verse full scale, so your Wing Cube Loading value is a good indicator that it should fly very much like the real full scale Pitts... its all good
Read here for a more in depth explanation of Wing Cube Loading
http://www.theampeer.org/M1-outrunne...unners.htm#CWL
John M,
10-21-2015, 09:28 AM
#5442
The hands on feel is one of the best ways (only way really) to dial a model in of course, but this WCL method just confirms it.
John M,
10-21-2015, 02:18 PM
#5443
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I have been burning through fuel pumps like they were disposable. During the event over the weekend I saw some that the guys were using, particularly a club member. He love's his pump but did not know where to get one. So I spent a few hours searching to no avail. Then I posted a picture of it on GSN and someone told me where to get one. So I ordered two, one for fuel and one for smoke. I have received them, installed them, and "Man" I love these thing's.
Check them out at "Jersey Modeler".
http://www.jerseymodeler.com/id29.html
Check them out at "Jersey Modeler".
http://www.jerseymodeler.com/id29.html
10-22-2015, 11:14 AM
#5446
My Feedback: (3)
ROFLOL!
I used to burn through powered pumps on almost a weekly rate and it got expensive. So I tried keeping records and comparing brands of pumps. That lasted one season where I determined that the difference between short and long life was less than a month. Some failures were the coupler between the motor and the pump, some were the pump it self failed, and a few were the motor would give up.
So changed my ways and went to hand crank pumps. I discovered that they tend to last for about a season and then need to be replaced or rebuilt, depending on what was being pumped. That was frustrating.
Since then I found a free pump that always works. Of course EVERYONE always laughs at me, but my method always works and I never have to rebuild or replace the pump.
I mount a hand crank pump to start the siphon in and out and let gravity do the work.
It takes a little time that I use kibitzing with friends and fencing with foes (yes, club officers DO get some of those! I have been told that it comes with the territory
) while my 'pump' does its job.
I used to burn through powered pumps on almost a weekly rate and it got expensive. So I tried keeping records and comparing brands of pumps. That lasted one season where I determined that the difference between short and long life was less than a month. Some failures were the coupler between the motor and the pump, some were the pump it self failed, and a few were the motor would give up.
So changed my ways and went to hand crank pumps. I discovered that they tend to last for about a season and then need to be replaced or rebuilt, depending on what was being pumped. That was frustrating.
Since then I found a free pump that always works. Of course EVERYONE always laughs at me, but my method always works and I never have to rebuild or replace the pump.
I mount a hand crank pump to start the siphon in and out and let gravity do the work.
It takes a little time that I use kibitzing with friends and fencing with foes (yes, club officers DO get some of those! I have been told that it comes with the territory
) while my 'pump' does its job.
10-22-2015, 11:31 AM
#5447
I use one of those manual Dave Brown Six Shooter fuel pumps for gas; getting tired of the cranking though... I've been tempted to use a couple of these universal automotive electric inline fuel pumps, they're only $10-15 bucks each... 2-3.5 psi @ 28 gph, should work nicely.
John M,
John M,
Last edited by John_M_; 10-22-2015 at 11:40 AM.
10-22-2015, 12:31 PM
#5449
Dave Brown makes a six shooter glow fuel pump, but its manually operated.
Well... Mr Gasket makes a micro electric fuel pump for ethanol / methanol use model #12E... I don't know how compatible it would be with glow fuel though... you would need two of them, as they are uni-flow positive flow in one direction, so you use one to fill the tank and another to remove fuel from the tank... for glow fuel it maybe more piratical to get one made specifically for the hobby and is reversible.
John M,
Well... Mr Gasket makes a micro electric fuel pump for ethanol / methanol use model #12E... I don't know how compatible it would be with glow fuel though... you would need two of them, as they are uni-flow positive flow in one direction, so you use one to fill the tank and another to remove fuel from the tank... for glow fuel it maybe more piratical to get one made specifically for the hobby and is reversible.
John M,
Last edited by John_M_; 10-22-2015 at 12:34 PM.