Slow Stick Prop Reversed

[pizzano]

Just for grins, I felt compelled to video a test to see if the Slow Stick could get any lift with a 10x5 prop (reversed) installation.

Forgive a few of my verbal slip-ups like prop installed "up-side down". Had not finsihed my 1st cup of coffee yet...lol

The 1600mah, 7.4v battery was fully charged (it's 40c rated, not 30c as I mention in the vid) and the outrunner is a Power Up Sport 400, rated at 1050kv. She pulls approx. 22 ounces at 22 watts (yes tested) with the 2cell -APC 10x5 prop....more than enough to get this 18oz stick off the ground due to the lighter weight than using a 450 outrunner and 3cell 1800mah battery.

SS Reversed Prop 3-11-13

The attempt was against the wind. Did not try with the wind since it started gusting...into the gusts, it did not lift......this plane will normally lift, with head wind, at full throttle, with 15' to 20' of runway.....for the test, I tried more than 160'.

Had fun doing this......the next test will be with a 3cell, 1800mah, 30c rated lipo, same prop.....the 400 outrunner and ESC will handle it. I've flown with that set-up previously, but preferred the C/G of the 7.4v better and get substantially longer flight times.

[mclarkson]

You need a bigger prop!

[pizzano]

LOL.....with the 10" installed, I've got 4 more inches to spare....heck ya! But I'll be abusing my poor little 400 outrunner.....lol

[pizzano]

Got up early before work and wind......tested a 11.1v 1800mah and a 2200mah on the 400 outrunner...used both the APC 10x5 and GWS 10x4.7 props, don't have anything larger.........no vid since the results were the same as the previous test.....no lift. However, my motor and ESC (30amp) did get hot...not extemely, but considerably hotter than with the 7.4v.

I have an older 450 outrunner that the shaft isn't pefect but stable....quickly slapped that on Stick with the 11.v 1800mah, 10x5 prop.....the test results were a little different, actually got about 6" of lift before I ran out of runway (+180').....didn't have time to finely tune the C/G but it was close enough to test.

I guess a bigger prop and 300' feet of runway might get me in the air........lol

I've summized that this Slow Stick won't fly with a reversed prop and 400 outrunner. With a 450 and bigger battery you get lift but I seriously doubt flight (unless one considers 6" of lift, flying, I guess the Wright brothers would have)....lol.

This concludes my testing of the reversed prop syndrome....it's been enjoyable and has reaffirmed what I suggest to all the newbies I come into contact within the RC hobby world......."prove it to yourself first before you assume it must be true"......particularly if it is an "internet opinion" posted by an experienced authority, especially what I post as well.....lol

[Rockin Robbins]

Originally Posted by pizzano

I've summized that this Slow Stick won't fly with a reversed prop and 400 outrunner. With a 450 and bigger battery you get lift but I seriously doubt flight (unless one considers 6" of lift, flying, I guess the Wright brothers would have)....lol.

Actually, the Wright brothers' first flights were low on purpose. They had three years of gliding experience under their belts and were well aware that the most severe hazard to life and limb was if they were able to severely bank the plane and catch a wingtip. This being a much heavier plane than they had crashed before they were understandably cautious.

However, Wilbur's fourth flight of the day, he took her up considerably higher and flew considerably longer.

I understand that Europeans try to make fun of the Wrights, but they don't understand their history. The Wrights were first to leave the ground under power, fly with 3 axis control systems and return to the ground at a point higher than that where they took off, landing without a crash.

Europeans of the time had no control systems at all, relying on self-stabilizing, non-controllable airframes and tiny hops. When the Wrights toured France, taking flights of 30 minutes they temporarily silenced the hoity-toities who made fun of them No one else had flown for even five minutes. The Wrights flew circles, figure eights, climbs, descents, banked wings at will, all maneuvers beyond the capabilities of any European planes of the time. Royalty from all Europe came to France to witness what their press had called impossible.

Now, of course, all that history has been forgotten and replaced by fairy tales. The Wrights only flew four feet off the ground. They weren't first (of course not if you redefine flight!). Hogwash.

The Wrights flew in winds that would tear apart any European airplane of the time. They actually LIKED 30 mph winds.

[pizzano]

My previous comment about the Wright's was purely in jest......completely aware of the true definition of "flight".............. Those dudes were serious mechanical engineers, very brave and determined inventors.......and way ahead of anyone in the world at the time when it came to flight testing (wind tunnel) and design.

I have a very close friend who is a semi-retired commercial pilot. Flew for UPS for years (Air Force trained and flew C-141's). He shared these photos with me back when I was a younger and all excited about flying RC planes (surprised I still have them):





As one can see, the prop's must be at least 8' long and the pitch faced in the proper direction to get "lift"...be it pulling or pushing. I'll bet many different configurations were tried in order to get enough torque and rpms out a 12hp-4cylinder combustible, combined with their "bicylcle" gearing..............and they probably even "reversed" the prop pitch just to gather more data......sounds familiar.....lol

Good stuff Robbins!

[RepRapper]

Wow this is the most trouble I have ever seen anyone go to too prove that someone was right! The original thread was of a new (begginner) pilot asking for help because his Slow Stick wouldn't fly over two feet as I recall. One well meaning eperienced Slow Stick Pilot suggested that the begginer check to make sure his prop was mounted facing forward is if it was not it would greatly reduce THRUST making flight nearly impossible. In one of the following threads the (begginer) had checked the prop and said it was on the right direction. Case closed. I find it surprising that some one would actually try to fly an airplane with the prop on backwards. Still I found it interesting. I think I could fly my slowstick with the prop on backwards I noticed that it takes a lot more thrust to move an airplane on the ground then fly it through the air. At least that is the way it seem to me, I have noticed that when my wheels leave the ground and the drag of the wheels stops the airplane accelarates more quickly after leaving the ground. The airplane in the video was going faster and faster when it simply ran out of runway. I think it could have gotton airborne. May have to try it some day

[pizzano]

It took all of an hour to test the plane (3 set-ups), another 35min to Photoshop and a few more minutes to post......no trouble at all Rapper....thanks for the encouragement!

[Rockin Robbins]

Amazing job there! Love it when somebody actually tests what we all "know" is true. In this case you proved it truer than I thought it was.

[pizzano]

Appreciate the acknowledgement Robbins...Thank You!

[hayofstacks]

Pretty funny. I thought the plane couldn't get any forward momentem because the prop reverse could only provide backward thrust .

Isn't funny how you pointed out that I was EXACTLY right about everything? I DID have about 3X the power as your setup, and YOU CAN fly with the prop on backwards. Funny how works out isn't it? Now, just for the sake of argument, what OTHER things had I done that YOU have tested that "don't work"?

And btw, even though I didn't have much power with the 10X6 gws prop, and it did take more runway, the plane had plenty of power to fly. I even did a couple of loops.

Let's have a quick exercise here on basic physics...

How does a prop work? Because I remember you saying that the prop works soley based off of the airfoil of the propeller, meaning that if you reversed the prop it could only move air backwards. Now, I want you to pick your propeller up, look at the direction of the pitch. Now flip it over. Notice how the pitch still faces the same way?

On a apc prop, it has quite a bit more of a twist at the hub and is a much heavier prop. On a gws prop, it actually looks nearly identicle either way.

Anyways, I look forward to what else you have all figured out that I was right about.

[Rockin Robbins]

Originally Posted by hayofstacks

Pretty funny. I thought the plane couldn't get any forward momentem because the prop reverse could only provide backward thrust .

<BS....BS.....BS....BS>

Anyways, I look forward to what else you have all figured out that I was right about.

Well, THAT was in very bad form..... As a matter of fact it was crudely rude.

[pizzano]

It was a great day for Slow Stick flying, dead calm all morning.......three club buddies and I took our selection of sticks (7 total) to the local mall parking lot and put on a little show......before the shoppers started showing up (we had an area delineated off, with permission). First time I've ever been in the air with 3 other sticks at the same time. One of the wives was filming......If I get a copy, I'll post it here.

Love these Slow Sticks!

[pizzano]

Robbins...

I've got guys like that set on the IGNORE list now (there are a few of them here, one with +42 years of experience just showed up recently...lol)....it's really not to bad here, as forums go, considering the number of users and members....It's actually refreshing.......good oversight and thoughtfull guys monitor this site well!

I've been around the RC forums since 2006, was even a Mod/Admin for a year at one of the Heli forums (verifiable). That experience has taught me it offers no positive result to anyone when an individual can't refrain from patting themselves on the back or beating their chest at every oportunity they get in order to gain credibility and attention......it only serves one person, the one out of breath with tired arms!

[Rockin Robbins]

I only said something because that isn't the norm for Wattflyer. If it was that other forum I would have just expected it an not reacted.

I don't care what your ideas were going into the experiment. I think it's really neat that you did the experiment and quantified the results and posted 'em. I would have guessed it would be like hayofstacks said buried amongst the chest thumping, that the plane would fly, but half as well. I was blown away that your propeller wouldn't even take the plane off the ground when on backwards.

I don't care what somebody knows or doesn't know, or even if he's proved right by the experiment. The kudos go to the experimenter. You ALWAYS start out with some kind of hypothesis. Without the experiment's results they hypothesis plus $4.00 will get you a cup of coffee. Even if the hypothesis is 100% correct it's worthless until it's been tested and quantified.

[hayofstacks]

Originally Posted by pizzano

LOL...."as silly as this may sound".....getting a SS to lift "off the ground" more than 2' with a 10x6 prop on back-wards"..... not keeping it in the air or hand launching it....

I just tried it again (ground launch) on both SS, with ailerons and one without, 10x5 APC and 10x4.7 GWS props, 400 Sport Outrunner, 7.4v 1600 lipo........with a head breeze of about 3mph........I may just vid this to prove the point!

I'm getting absolutelty no positive forward lift, (other than the breeze), from this set-up The tail just wiggles and plants it's self into the ground.......what am I doing wrong......lol (other than responding to this nonsense)....lol...it's on the internet, so it must be true....lol

Is this info really helping Dan out....? Probably some (I hope). If anything, he's quickly found out that although many are willing to give advise and have good intentions, there's nothing better than gathering all the info you can get, apply what makes "sense" and what you can safely accomodate and pass the rest off as "grains of salt"!

Dan, hope you get the issue sorted out. There are many good ways to solve a problem, many here are very experienced and provide pratical, safe methods of application. Use caution, and verify your sources of information.

Originally Posted by pizzano

Hayofstacks.......I give up.....lol

Sorry, I don't trust your math (1/3 the power).....I'm running with a 400 brushless and 10x5 prop, 7.4v 1600mah.......since, regardless of the additional wattage your 450 may be able to pull and the amount of rpm's it can deliver....the backwards prop is forcing air flow in the opposite direction of any of the planes air surfaces.....

The incremental "backwash" the prop provides reversed has little to no lift.... "Lift (or forward motion) is created by making the air pressure lower on the front of the propeller blade than the back so the aircraft is actually being pulled / pushed forward by air pressure rather than being pushed by thrust"...straight from Aviation Digest.

I've been following many of your posts. Quite honsetly, I've lost confidence in your suggestions. Especially after having tested a few of your ideas (which I do with any source I find suspicious, impractical or abusive (un-safe or harmful to the equipment) much like the care you've exhibited during flight of your Slow Sticks....lol

I think, from what I've seen lately, it would be best for me to just avoid any of hayofstacks future posts. Experience tells me nothing positive will gained by continuing to fight an up-hill battle of wits.

Dan, I appologize for the high-jack of this link......hope there will be others here more knowledgeable about the SS then myself, that will chime in with ideas.

This is what was said. Not once did I say a negetive thing. Yet I was personally attacked for suggesting that a plane would even move forwards with the prop on backwards.

The problem was that the op could only get the plane a couple feet off of the ground and was lacking in power, exactly what was "proved", as I suggested to begin with. Read it for yourself. http://www.wattflyer.com/forums/show...516#post903516

I was personally attacked and called an idiot for saying that I accidentally threw a prop on backwards trying to get one last flight in before dark. There was no chest thumping or nut size contest. I was just sharing my experiance hoping to help another slowsticker trying to solve his problem.

I've been on forums since 2002, and this is the first time anyone has called me out and "hit the ignore button". I don't take it personally, its just the interwebs guys.

Ignorance is bliss.

[Rockin Robbins]

Hey hay. People read your post. There's no denial possible. It was pure posing as king of the mountain and ridiculing pizzano. There was no reason to do that.

Folks, don't believe what I say about it, read hayofstacks' post. It's regrettable.

[pizzano]

Robbins........

LOL....I had to read that last post.....sounds more like a "I'm the victim" cry......all those personal attacks....shame on me!

Back to the ignore button........lol

[hayofstacks]

Like I said, ignorance is bliss.

Guess I'll have to make my own slow stick prop reversed video.

[hayofstacks]

And I didn't intend to make fun of anyone. I was just pointing out that the pitch for the prop is the same even if the prop is backwards. I ws the one getting called an idiot for saying that you would get forwards thrust.

It was pizzano that was bragging about how he could prove it wouldn't, and that it couldn't provide "lift". (Pretty sure he either ment thrust, or he has no idea what lift is). And then "quoted" aviation digest.

I don't believe everything I read, especially on the internet. But I also don't call bull unless there is a reason why.

[Rockin Robbins]

Eh, it's all good. Hayofstacks could easily not have known how a neutral person would or could read his post. I'm not putting him on ignore and I don't think he needs to stand in the corner with a dunce cap for an hour (even though that would make a great video!)

I like the idea of making your own video. Make sure to tell us all the goodies: motor make and size, prop make and model, etc. All up weight would be cool too.

Depending on what combination they have, everybody is going to get different results on this. Only one thing you can say for sure. The plane won't fly as well with the prop on backwards if the prop is right for the plane when it's on correctly.

If you have a really lousy prop, like a Master Airscrew, you might not get a lot of difference between forward and backwards.

[Azarr]

Reduced thrust by putting on the prop "backwards" has been used by modelers since we started flying. It's a common thing in the Free Flight discipline for flight testing, it's the only control over thrust they have and normally the first couple of trim flights are done this way.

Azarr

[Rockin Robbins]

Originally Posted by Azarr

Reduced thrust by putting on the prop "backwards" has been used by modelers since we started flying. It's a common thing in the Free Flight discipline for flight testing, it's the only control over thrust they have and normally the first couple of trim flights are done this way.

Azarr

As usual those free flighters beat us to the test there. There's a huge body of knowledge in free flight planes that we RCers ignore. That's our loss and it's bigger than we think.

[hayofstacks]

Azarr, you gotta remember, I'm the idiot, it was proved in his video. A slow stock cannot fly with the prop reversed. No plane could.

[kyleservicetech]

Originally Posted by pizzano

Just for grins, I felt compelled to video a test to see if the Slow Stick could get any lift with a 10x5 prop (reversed) installation.

LOL
Yesterday, I was placing the wing on my little 24 inch wingspan model of some 15 years ago, and had it on backwards. Where the trailing edge was up front, and the leading edge was in back. Would never have taken off though, the slide on canopy would not fit.

The bad thing was, one of my club members saw me do it!