Hip Pocket Builders' Forum

Indoor Free Flight Forum => EZB, 35cm, Ministick, AROG, Livingroom Flyers => Topic started by: jjlain on September 16, 2015, 04:06:14 AM



Title: Propeller for "The Fly"
Post by: jjlain on September 16, 2015, 04:06:14 AM
Hello

I'm generally a newbie to free flight models and totally so for indoor ones, and wondering about the propeller for "The Fly" rubber model.

I'm building from the plan, so there's no kit propeller for me to use. So, what kind of propeller should I choose and what shoud/could it weigh? The plan & website are quite vague about that question, apart that the kit propeller comes from europe?

I can attempt building one, or use a commercial one. Would someone be so kind to point me in the right direction, what kind to (try) build or which commercial one would be suitable? In the plans gallery someone had left a comment about an interesting conversation about the model in question, but I cannot find it with the search tool.

Thanks in advance!

Jaakko,
Finland





Title: Re: Propeller for "The Fly"
Post by: Tapio Linkosalo on September 16, 2015, 04:46:43 AM
Ilmailukauppa in Helsinki sells the Ikara palastic propellers for indoot rubber, for example the 150mm diameter (http://www.ilmailukauppa.fi/shopnew/muovipotkuri-kumimoottorilennokkiincomplight-150mm-p-8908.html). The prop looks like Ikara made, but the dimensions are indeed not stated on the drawing! (Tim, you should add this data to the web page!)

In Finland, you might also consider building a model for the "Peruslennokki (http://lennokit.net/showthread.php?t=40308)" class, where there are a number of other fliers and also contests. It is more fun to join others for the flying! (For non-Finnish readers, Peruslennokki is our national beginners class, rather similar to Science Olympiad models: min weight 6g, monowing max dimensions 480*80mm, tailplane max 45% of wing area, max 250mm diameter prop)



Title: Re: Propeller for "The Fly"
Post by: jjlain on September 16, 2015, 05:44:43 AM
Thank you for the prompt reply Tapio!

I'll have to visit there some suitable day, I'm also lacking the rubber for the plane. This one is mainly for the joy of the kids (and me) if it ever flies.

For the next one I might build I'll think about Peruslennokki, but am also thinking about an outdoor glider of some sort (maybe around 1.5 m span).

Thank you!

-J


Title: Re: Propeller for "The Fly"
Post by: Tapio Linkosalo on September 16, 2015, 06:55:30 AM

As you mention to "visit" Ilmailukauppa instead of placing the order by mail, I gather you are from Helsinki area. So you might be interested in visiting our bi-weekly indoor flying session at Sompio (http://lennokit.net/showthread.php?t=62163) school on Kerava. Every other week the gym is used by Indoor RC people. Also the bulletin board lennokit.net is worth paying a visit, there is plenty of discussion on indoor models (and others) there.


Title: Re: Propeller for "The Fly"
Post by: adanjo on September 17, 2015, 03:20:59 AM
Hello

I'm generally a newbie to free flight models and totally so for indoor ones, and wondering about the propeller for "The Fly" rubber model.

I'm building from the plan, so there's no kit propeller for me to use. So, what kind of propeller should I choose and what shoud/could it weigh? The plan & website are quite vague about that question, apart that the kit propeller comes from europe?

I can attempt building one, or use a commercial one. Would someone be so kind to point me in the right direction, what kind to (try) build or which commercial one would be suitable? In the plans gallery someone had left a comment about an interesting conversation about the model in question, but I cannot find it with the search tool.

Thanks in advance!

Jaakko,
Finland

Jaakko san,
If you want to buy the prop, you will be able to get it from Mike Wood house of Free Flight Supplies in U,K,.
http://www.freeflightsupplies.co.uk/
Click 'Indoor' and 'Rubber Accessories'. You will find IGRA RUBBER MODEL PROPELLERS.

It is 150mm dia and the max blade width is 25mm, weighes 1.04g (with plastic bearing parts, without a prop assy hanger on the plane).

Aki


Title: Re: Propeller for "The Fly"
Post by: jjlain on September 18, 2015, 12:55:17 AM
Thank you for your reply Aki. This time I think I'll go for the Ikara one Tapio mentioned, that I can get by driving to the store, but I'll bookmark that webstore for future needs.

Tapio, maybe one of these days I'll come and visit the Sompio school, but free time is pretty scarce at the moment. But one day maybe!

-Jaakko


Title: Re: Propeller for "The Fly"
Post by: Tapio Linkosalo on September 18, 2015, 02:55:42 AM

I think we are talking about the same props here, http://www.ikara.eu/index.php?nid=6259&lid=en&oid=953446 . I do not know why mr. Woodhouse calls them IGRA props (except that there seems to be a P-30 prop called Igra, however I thought that came from the same factory as these indoor props).



Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 18, 2015, 04:14:16 AM
Hi,
Anant from India. I built a FLY from plan and used IKARA 6" prop and the nose hub which I bought from Ikara website as there are no dealers in India. In fact Indoor Free Flight is yet to become popular in India. Everyone here is into RC stuff.
The FLY flies well. Will post a youtube link of my Fly in flight.
Need to adjust balance by pushing tail boom in or out a bit.
Made a carry box from my dogs food carton.
See attached pics

Happy flying
Anant


Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 18, 2015, 05:04:17 AM
Hi,

Here is a youtube link of a short video of the Fly in flight in my living room. Did not give too much turns as I wanted to avoid it hitting the roof.

            https://www.youtube.com/watch?v=eqgk0g1RX04

See the other test flights of some models I made in the Foldnation channel.

The Biscayne Baby is another good living room stick to make. Flies well. Uses the same prop as the FLY. See the test flights at this link.

          https://www.youtube.com/watch?v=DqRpv1k-ENI

Anant
India


Anant


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on September 23, 2015, 09:31:37 AM
Build the propeller yourself, e.g from the plastic yoghurt cup. Cut it diagonally at about 15-17 degs for the 5" prop. Than sand the blades on the bottle, also under an angle. Use bamboo spar from the splitted skewers and ca the whole thing together. Use pin/mw for the shaft. You will get way better result than ikara prop itself. (Way lighter). One blade in my case is about 0.15g average. The whole prop would come out at about 0.4-0.5g depends on the size. Ikara prop blade is just an ellipse, but you can test other shapes also. Example can be found for instance on my website tutorial for beginners:

http://clubmedia.eu/bamboo_poonker/index.html

Oh, in place of teflon washer, which you need to order from some weird websites from US, just use plastic from bottle caps like coca-cola and drill hole inside using flatten and cut pin. (Idea from someone on that forum, works like a charm). One washer only :)

For the bearing the best is to bent your pigtail bearing from mw/pin or use top part out of aluminium can, like shown under the link I pasted.
But go for pigtail, its super easy once you bent one or two. This will allow you to set your thrust angles for trimming...

good luck :)


Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 24, 2015, 05:05:10 AM
Did not realise that only JPEG attachments are allowed. I attached PDF and Doc files.
Now converted to JPEG

Dont know if my last post had the template attachments.

Here it is again anyway as JPEG

Anant


Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 24, 2015, 05:07:29 AM
Yes making your own prop is also possible and also maybe more satisfying for a scratch building enthusiast.

Fitnezz your page with instructions is really good and useful for someone getting into this type of aeromodels. That too with commonly available materials.

Can also use a very small glass bead as washer. Should be available in a craft/hobby store that sells beads for making bracelets and necklaces.

I have also downloaded and my earlier post gives some templates for propellers that I saw on a website. Can printout and put on to a plastic cup and make it.
Different sizes and shapes. It can also be taken to a graphic software and also scaled bigger or smaller according to requirement.

Anant


Title: Re: Propeller for "The Fly"
Post by: Tapio Linkosalo on September 24, 2015, 05:43:49 AM
A word of warning about the glass beads: several years ago I was flying by SciOly model in a large hall (22 meters ceiling), and had problems getting the model climb enough. Reduced the back off more and more, until I was almost flying without backoff at all. The model had an Ikara plastic prop, similar to the one as "the Fly" has but 240mm in diameter. The bearing was also a plastic one made by Ikara. At some point I took a closer look at the prop and realized that the red glass bead for bearing was covered with grey dust. Similar calour as the bearing. Also the front surface of the bearing had turned concave. Apparently the bead was grinding the bearing! I did not have any substitute bearing material at hand, so for emergency repair I added a tiny drop of rubber lube to the bearing. Just in case increased the backoff a lot, and yet my model climbed steeply and crashed to the ceiling in 30 seconds. Whew!

So, some glass beads may be rough in surface. Not recommended!


Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 24, 2015, 10:28:30 AM
Yes the glass or plastic bead could have a burr when the hole is made that will cause the problem you mentioned.

It is noticing these little things that adds to ones experience and expertise. Thanks for the info.

Some beads are good quality and one can feel the surface at the hole to feel any burrs. Any way better to have something that is as soft and smooth as the plastic bearing so it does not grind it.

Maybe as a standard routine use a small drop of oil like the light oil used for sewing machines or maybe even castor oil. Castor oil is the lubricant even in real airplane engines and also for gas engines of aeromodels. Have flown control line models with gas engine which uses a mixture of Kerosene-ether and castor oil.

Flew my FLY in the local college badminton court which has a high roof. 500 turns gave me a 40 sec flight. Perhaps if I increase the length of the motor and stretch wind it it will give a longer duration. Lubricated the rubber with hand wash soap.
Will upload the video on youtube and post the link.

Anant

Anant


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on September 25, 2015, 06:00:28 AM
Also, take a look here, dude creates the blades out of the floam stuff formed on a hot water container :)

https://www.youtube.com/watch?v=ZnzZJWhpYys


Title: Re: Propeller for "The Fly"
Post by: jjlain on September 25, 2015, 05:10:21 PM
Thanks for the replies and advice everyone!

I bought the Ikara propeller for my Fly, but maybe I'll experiment with building one! And also make a pigtail bearing. I made one out of a bit of balsa and a a few mm of carbon tube and it's quite brittle. And not really adjustable.

I test flew the model at my livingroom, but the turn radius was way too big. Next I tried it outside on a very still night, it flew maybe 10-15 secs on 100-ish turns on the rubber, in circles of maybe 5-6 m diameter. What's the way to control the turn radius? Tail tilt?

Also, the climb wasn't really spectacular, the plane flew at maybe max 3 m height. Has it more to do with wind's on the prop or trim? I have a small up angle on propeller. If the CG is supposed to be controlled by moving the boom back & forth, mine is useless for that at the moment. I cracked the boom a bit and wasn't bright enough to remove the boom for fixing --> I guess some sort of capillary action sucked the ca-glue into the paper collar and now the boom's stuck.

-J


Title: Re: Propeller for "The Fly"
Post by: adanjo on September 26, 2015, 12:44:36 AM
JJ san,
Have you read ' The FLY ' thread in this forum?
http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=14215.0


Title: Re: Propeller for "The Fly"
Post by: Tapio Linkosalo on September 26, 2015, 12:45:53 AM
In my models I set the "baseline" turn with rudder (tailplane offset) and left thrust, and then fine-tune the turn with tail tilt (no tilt in large halls, and more tilt when I need to make the model turn more tightly.

And one thing that I always want to preach when talking about indoor models. I do not use cyanoacrylates. They are heavy (it is hard to control their use to apply little enough), they are brittle and also make the balsa brittle and you cannot dissolve the glue joints in case you need to take something apart e.g. to adjust the trims of the model. Ordinary old-fashioned "model glue" (celluloid glue, Uhu Hart is the common brand in Finland) thinned 2:1 with acetone and applied from a needle-nose bottle works best for indoor model building.


Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 26, 2015, 11:06:08 AM
Talking of turning problems.
This probably should not be on this thread. But since the discussion of turn and radius came up I thought I would mention this.
I built a double whammy and an A6. Both are taking right hand turns whereas the design is supposed to make it take left hand circles. Still working on test flights and figuring out how to correct this.

As for climb angle, my limited experience has shown that the main wing angle of incidence greatly affects flight performance. Of course the FLY has fixed main wing and no tissue tubes to adjust angle. Perhaps if the wing posts are accurate according to plan you get the required incidence. I found that adjusting the tail boom in or out then gave a good trim. What I did was to use a marker pen to mark the exact depth the boom is to be positioned so that after dismantling I can assemble it again accurately and not go thru the whole trim process next time I fly it. Same for wing incidence in other
models with tissue tubes for wing posts.

Anant


Title: Re: Propeller for "The Fly"
Post by: jjlain on September 28, 2015, 03:54:45 AM
Thank you again, everyone.

About the CA glues, I guess it's live and learn for me, more patience and care with the next model. I used SIG Bond on the Fly, but also the cyanoacrylate as mentioned.

-Jaakko


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on September 28, 2015, 05:42:01 AM
If you are beginner (like me) and will be happy your Fly would do about 3 minutes, do not worry about the glue type and cosmic light-weight. Do it clean, trim it good, match prop and rubber. The Fly made with CA can easily do it. Later, on the expert level that does matter, but if beginner will be busy with weight too much, he would skip what is really important. Knowledge of aerodynamics + trimming.

success,

Jan


Title: Re: Propeller for "The Fly"
Post by: Glidiator on September 28, 2015, 08:46:56 AM
Yes very true fitnezz

As a beginner too in indoor rubber band free flight I am yet to get a good over 1 min flight.
My last flight with the FLY (42 secs with 500 turns) gave me confidence that if I increase the length of the rubber loop and stretch wind it I should get a long flight of over 1 min. The indoor space should also have sufficient unobstructed height.

I have concentrated on building the models as accurately as per plan and here in India you dont get the various options of balsa various densities required to make strips of required weight as the professionals do. . Yes the trimming is the biggest learning experience. Have been using CA adhesive as it dries fast. Need to use very little and apply carefully not to let it wick to places you dont want it to go.

Anant


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on September 29, 2015, 03:35:56 AM
You should get over 2, 3 minutes Anant easily using average balsa, looking at the size of the space you fly in. Get best parts of the sheet as described in Coslick's hobbyshoper and you will be absolutely fine. This is video of my Fly doing about 3 minutes in the attic kind of interior ;) https://www.youtube.com/watch?v=Wsd8PIEItr8 This is just hobby shop crap balsa + lightweight sandwich bags for covering. All CA. Weight about 0.7g. Expert materials are for experts you know :) Dont bother with that, if you dont plan going contest...

best,

P.S. Looking on your videos Anant, it seems that you use a bit too much power. Go for lighter balsa prop and thinner rubber.

Jan


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 08, 2015, 11:37:12 PM
Hi fitnezz,

Here is the link of my FLY doing 42 secs.

https://www.youtube.com/watch?v=QbjuhjDW_g0

The thinnest rubber I had was the rubber that came with the Carbon Butterfly I got from Ikara.
The next thinnest I have is 1/16 rubber I got from FLYM.

I used the carbon butterfly rubber for this flight. Have some more length. If I make a longer motor and stretch wind it to max turns should get a good long flight.
Is the trimming and climb rate okay from what is seen in the video?

Anant


Title: Re: Propeller for "The Fly"
Post by: Twinchicky on October 09, 2015, 12:06:26 AM
I've never built a Fly nor am I very familiar with them, but I think I could still offer some help.

The model in the video looked like it really wanted to sideslip to the left late in the cruise, and it seemed to be pulling a very hard left bank (e.g. left wing tip lower than right wing tip) the entire flight. This is clearly due to the extreme amount of stab tilt - I would take out most or all of the tilt in the stabilizer and instead use boom angle and left thrust for turn. Past a certain point, more stab tilt doesn't do much for turning radius and only makes your model less stable (and less efficient).

Also, that motor is running out of turns barely into the descent. You need a much longer motor, probably more than 2 times the length of what you're currently using. Then you'll really see the times go up. The Fly is somewhat similar to an AMA ministick - ministicks commonly fly with 3000 or more turns in a disproportionately long motor. I'm going to take a wild guess that you could be flying on around 1500-2000 turns on a longer, better motor.

P.S. Another observation - 500 turns used up in ~35 seconds of that flight means your propeller is running at somewhere around 800 rpm. This is really high, even for such a small, heavy model. Since you don't have thinner rubber, I would suggest increasing the pitch in the propeller by twisting the prop spar so that the blade angle on each side is closer to parallel to the direction of flight.

P.P.S. Here's master indoor flyer Aki Danjo's FLY - https://www.youtube.com/watch?v=ZfXKTPO_UmE
Notice how his model flies with very little or no tilt in the stabilizer and it still turns quite tightly.


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on October 10, 2015, 08:14:51 PM
What helped me was going down with the power. So, apart from trimming mentioned, I suggest you use 1/16 rubber you have, one strand, not loop about 10" long. And go up to 12". That will not be enough power though to use propeller from ikara. You have to have balsa wood prop, which is not difficult to make. That strand of 1/16 will allow you to put ~ 2000 turns and more. That means, that the model needs to be less than one gram also. Easily you can go to 0.7g with balsa prop as I mentioned before. No expert materials are needed for that. This will increase flights to 3minutes and above.


Title: Re: Propeller for "The Fly"
Post by: lincoln on October 11, 2015, 12:38:08 AM
I think this is the model we're talking about, isn't it?:
https://theflyadelaide.wordpress.com/

Seems to me that most of the weight will be in the prop, the bearing, and the rear hook. They look awfully bulky. And I don't see how the model could be balanced without tail weight, unless you are using Guillow's wood* to build it. The model seems to resemble a Mini Stick. Recommend you use a homemade or Harlan bearing up front, and some kind of wire hook at the back. On a model this small, you can probably use wire around .010, or possibly even smaller. (read: use the smallest string from a guitar). If you use wire and/ or a Harlan bearing, plus a homemade prop, you should be able to get down around a gram and a half, or even less. Without going nuts. For ideas on bearings, hooks, and homemade props, you might check out the Mini Stick articles and plans at: http://indoornewsandviews.com/ and http://www.indoorduration.com/  You might find the article for the No Non Cents pennyplane handy as a reference.  It's quite well written. http://www.rcgroups.com/forums/attachment.php?attachmentid=2294852  But remember that's a MUCH larger model. Also, if you're using information about props from a Mini Stick article, you will probably want to go with a much smaller prop.


*I have measured Guillows wood at something like 23 lbs/cubic foot. That's a specific gravity around 0.37 or so. The lightest wood I've used successfully is about 3.5 lbs! The average run of balsa is around 8-12 lbs, isn't it?


Title: Re: Propeller for "The Fly"
Post by: lincoln on October 11, 2015, 12:42:43 AM
P.S. If you have a reasonably sized flying space, you may find limited pennyplane easier to deal with. I think the Cezar Banks design is supposed to be good, as well as the No Non Cents. I once helped a beginner get over 5 minutes under a 35 foot ceiling with a limited pennyplane. (Or is it Novice Pennyplane?) I've had my current pennyplane for many years, and I don't remember where I got the proportions, though I'm pretty sure the second prop was from the Banks model.


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 11, 2015, 12:20:25 PM
Hi all,

Thanks fitnezz for the inputs on rubber dimension. Will try out your suggestions. Over the last couple of months doing test flights is giving me appreciation of the effects of rubber dimension, length of motor, number of turns etc.
Made a torque meter today from instructions from http://www.gryffinaero.com/models/ffpages/tools/torque/tmeter.html
Seems to be working okay. Also made a jig to do winding off the model. So now I can get in the 2000 turns off the model without problems.
As for making a balsa prop -- a few  questions
Should it be the same Dia, pitch etc of the Ikara propeller.
Or will it just need to be a paddle propeller.
Made a propeller for my A6 a few days ago, and its test glides/ very low power flights are very encouraging. So now have better confidence in making own propellers.
Also keeping the weight in the 1gm range I will need thinner dimensions on the various components as we dont get balsa of various density here. It is just sold in 3 ft x4" sheets of various thickness. Have no idea of the density. I doubt the hobby shop even knows. As mentioned earlier I seem to be the lone Trojan dabbling in indoor rubber band free flight in India so critical issues like balsa density is yet to percolate into the scene. I should weigh a standard piece and calculate the weight per cubic foot.
Yes, I will get on to the limited penny plane as suggested.
Have just made a A6 that seems like it will give a over 1 min flight if I get the rubber motor length and thickness right. Breaking the 1 min barrier on any model will be nirvana.
Had a look at the Fly video by Aki Danjo. Will try the suggestion of reducing/removing stab tilt. And yes the motor does need to be longer.
The slew of various suggestions and analysis done of my test flight video just makes me appreciate how much there is to what seems like simple rubber band models. Enough to give any aeronautical engineer an inferiority complex.
Will  get back with the effects of implementing the various suggestions.

Pics of my A6 propeller and torque meter and winding jig attached.



Title: Re: Propeller for "The Fly"
Post by: Twinchicky on October 11, 2015, 03:35:57 PM
I very much second the recommendation of building a limited pennyplane. My first LPP (an original design) did 6:34 under a 35' ceiling at high elevation with decent rubber. I'd imagine 5 minutes would be attainable with Super Sport or whatever rubber you have.

Also, nice-looking A6 prop. I notice you've sort of knife-edged the sides - if you can get your sanding technique down, it's better to have a slow, shallow taper across the whole blade than a steep one right at the edge. It saves more weight and is theoretically also more aerodynamic. You might not want to make the edge super-thin though, as that increases the chance of making little dings and chips in the edges of the blades.

When you go to wherever you go to get balsa, bring a .01 or .001-gram scale with you and weigh the sheets. You can make up a little spreadsheet for density vs. sheet size, it's not too hard. I've found a couple pieces of 4#/ft^3 wood at hobby shops this way.


Title: Re: Propeller for "The Fly"
Post by: Tapio Linkosalo on October 12, 2015, 12:47:23 AM
Or, for Jaakko (the original author) my recommendation would be building a "Peruslennokki", as that sort-of beginners class sees the liveliest attendance in Finland. For the time being at least, as just two weeks ago I gave a course on building F1M-limited for 10 persons, and in a week there is another one for 5 more, so maybe this autumn F1M will pass the beginners class in popularity in Finland?! Fingers crossed!


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 12, 2015, 03:52:43 AM
Wish there was an enthusiastic indoor free flight group in India like there are in many places around the world.

Need to take the first step and start one in my state.
Maybe involve the technical colleges first.

Anant


Title: Re: Propeller for "The Fly"
Post by: lincoln on October 12, 2015, 04:29:54 AM
Hi all,

snip
Should it be the same Dia, pitch etc of the Ikara propeller.
Or will it just need to be a paddle propeller.
snip
Neither. While you can get away with a paddle prop, your times will be much lower with it. The same diameter is probably a good place to start, though. You could use the same blade shape as your existing A6, I suppose. But if you wet it, then strap it to an appropriately sized cylinder while it dries, you'll get a much more efficient propellor. Be sure to use much thinner wood. EZB prop blades tare usually less than .010" (0.25mm) thick (unless you have usable 3.5 lb wood, but don't try it yet!).

If you really want to get into this, you will find most of your questions answered much faster and more completely if you get a copy of Building and Flying Indoor Model Airplanes. One of the best books I've ever read, and probably responsible for my entry into the hobby. I don't know how hard it is to get in India, but it may be worth a bit of trouble.
http://www.indoormodelairplanes.com/
The No Non Cents article I mentioned earlier is pretty good, but not as extensive. At the moment, though, it's on line.  For specifics of Mini Stick models, which are quite similar to the Fly, the other links I posted will help. However, you should scale down the prop in all dimensions. A diameter half or 2/3 of the wing span is probably easier than the same as the wing span! (Most Mini Sticks have very large props compared to the size of the model.)

Pitch on indoor duration models is usually in the range of 1.5 to 2 times the diameter. It's probably easier to start with the low end of that range.


Title: Re: Propeller for "The Fly"
Post by: Hepcat on October 12, 2015, 05:26:07 AM
Glidiator et al

The chart below may be useful when buying balsa (as long as you have your scale with you).

John


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 12, 2015, 12:45:43 PM
Hi Lincoln,

Thanks for the inputs on appropriate propeller.
Did not understand what you meant that pitch is 1.5 or 2 times Dia. How does that translate into degrees that I can set on the pitch gauge.
As for thickness of balsa -- the minimum we get here is 1 mm. Can sand it down to 0.5 mm. And avoid the knife edge as observed by twinchicky.
Yes I can wet and strap to a cylinder at 15 deg tilt to give it the required twist.
Have downloaded the No Non Cents article Will read and digest it.
The book Building and Flying Indoor Model Airplanes is available thru amazon but it costs a bomb here due to import costs.
Need to put in a lot of building time to implement all the suggestions.
Anant


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on October 12, 2015, 03:23:56 PM
Gladiator,

I hope I will not say anything wrong, but thats how I do it:

Lets say I want P/D = 2.0 for the 5" prop. (just example). Than P = 2 * D, P = 2 * 5 = 10. Also P = 2*PI*R*tanFi, for 45 deg tanFi = 1, so P = 2 * PI * R. Than you can calculate R -> 10 = 2 * PI * R,
R = 10/2*PI That is distance you need to use on your pitchgague (distance from prop hub to 45 deg slant on gauge)

Also I put the photos of bearings of my 7" amateur airplanes and prop, may be helpfull...



Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 13, 2015, 10:50:24 AM
Hi all,

Thanks for the maths on pitch and distance of hub from the gauge.
And the balsa chart.

Built my own balsa prop for the Fly using the same profile and sizes as the Ikara 6" prop I was using earlier. Will need to build another Fly to test this prop as the first one has the Ikara nose hub glued.

My prop is lighter than the Ikara one and I can reduce the weight further by sanding the blades down some more to about 0.5 mm. It is now just a little under 1.00 mm.
Also I will be cutting the drive shaft shorter to the required length so that will remove some more metal and weight.

Pics of the two props weight is attached.
Anant




Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on October 13, 2015, 11:28:31 AM
Nice progress, but keep on sanding :) You should sand them so long, they become almost transparent. Than wet it, form on the cylinder to add helical shape and bake it (or just let it dry). Also my suggestion would be not to use the plastic pipe as connector (if you want to have not fixed pitch, use paper tissue tube instead). Only balsa + thinnest guitarr string for the shaft 0.011" ? :) The prop now is at least twice as heavy as it should, so not much of the performance gain will be noticed.

I am total noob in that, but I remembered, what someone smart said, that good prop is half of the success. Apparently
good prop + average airplane >> good airplane + average prop :)
Still good prop + good airplane is the goal, isnt it?

Did you watch float ministick & pennyplane videos?

https://www.youtube.com/watch?v=uNJy3AR7uzE

Have a long flights + a lot of fun :)


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 13, 2015, 12:12:11 PM
Yes. Need to bring the balsa thickness down drastically. Also will use guitar string and tissue tube. All this will bring the weight down considerably.
Yes I have seen the video.

Back to the drawing board to improve on the build details.

Anant


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 13, 2015, 12:20:24 PM
I had posted a topic in the workshop tips on using feeler gauges to get the thickness required.

I have found this a good way to sand down to desired thickness.
Check out this thread I posted

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=19441.0

Anant


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on October 13, 2015, 06:30:43 PM
One thing I forgot, the prop on my photo is also copy of ikara 1:1. to give you the idea of weight, we are talking about using hobby shop wood, the whole prop is 0.15g, which is still very heavy as for ministick...


Title: Re: Propeller for "The Fly"
Post by: Twinchicky on October 16, 2015, 01:15:10 PM
To give you an idea, here's a photo of one of my ministick props. 6.25" diameter, somewhere around 12" pitch. The high pitch means that there isn't much twist in the blades, but it's enough. http://imgur.com/X4tmMwm

The blade thickness is .014" or around .35 mm, and it's quite sturdy and could be thinner. Weight is 0.14 grams. My slightly larger 7" prop with a little bit heftier spar and the same blade thickness weighs 0.17 grams. I think that a 0.2g prop for your Fly should be no problem to make.


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 16, 2015, 03:04:23 PM
Have sanded another set of blades down to 0.5 mm. Weight I think was 0.15 each. Have soaked and put it on a cylinder for getting the twist. Can sand down even more to 0.35 as done by you.
Will remove from cylinder tomorrow morning and weigh again.
Just a very basic doubt. What is the direction of the wood grain with respect to the prop shape. Have seen some plans and articles that show the grain direction. Cant seem to find those references.
Will use tissue tube as hub to join spars. Would help in weight control


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on October 18, 2015, 08:44:55 PM
Hey Glidiator,

The grain direction depends on how much you want your prop to bend. I assume you are not using C-type grain balsa, so it is probably A. If the grain goes along with blade main axis (spar) the prop will bend more (esp if it is flaring type prop - take a look on the scaling down EZB topic, I learned about flaring props there). If the grain goes diagonaly against blade axis, it will bend less. I suggest you keep on sanding down as much as you can without destroying balsa sheet and let the grain go diagonally about 45deg against blade main axis - the blade will be stronger. And ikara propeller is not a flaring type anyway.

P.S. I dont know if it is truth, but I guess sanding more gives not only weight benefit. Thinner blades cut the air better and produce less drag. Please correct me anyone if I am wrong here - that is just my theory =)


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 19, 2015, 12:37:37 PM
Hi all,
Made a new propeller with balsa sanded down to 0.3 mm, grain 45* to length of prop. Total weight now down to 0.36 gms including bearing, nose hub, etc.
Will have to now shift the main wing posts to get the right balance on the plane as the design position was for Ikara prop which is much heavier (0.98 gms).
What is now required is to do a series of test flights.
My A6 is also awaiting test flights after correction of turning problem by giving the tail boom an offset. So also my Double Whammy.
Lot of testing to do. This time I also have a torque meter so will note readings and do some proper data recording.
Hope to break the 1 min barrier.
Pic of new propeller attached.
Anant


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 19, 2015, 12:51:45 PM
Fixed the 0.36 gms propeller to the Fly after removing the Ikara hub.
The balance is totally off. I guess the original dimensions of the wing and stab components was okay for the heavy Ikara propeller (0.98 gms).
Now with a propeller that is three times lighter the stab spars and ribs will have to be drastically reduced in thickness to get a proper balance.
Will  have to make a whole new model with much thinner components.
Anant


Title: Re: Propeller for "The Fly"
Post by: LivingRoomFlight on October 19, 2015, 02:39:28 PM
Anant,

Keeping fingers crossed, looks promissing :)
Probably pigtail type thrust bearing is the next thing to go.
You will definitely want to try to diferent propellers in your new model, right?
Oh, and I would not use paper for covering anymore.

Waiting for the new video.

cheers!


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 20, 2015, 11:47:51 AM
Hi,
Will have to build a swarm of FLYs to match the various propellers of different weights I have made.


Title: Re: Propeller for "The Fly"
Post by: Twinchicky on October 20, 2015, 05:55:13 PM
Anant,

I think using lighter covering will really help you out. Ray Harlan from indoorspecialties.com sells UltraFilm and SuperUltraFilm (Not sure if he ships to India, but his website doesn't specify). I use SuperUltraFilm for everything heavier than F1D and it's quite good. Using a plastic film instead of paper will save a lot of weight, and your wing structure won't have to be as heavy. There are many articles out there on covering with plastic films, including those on Ray's website.

Also, from the photo of your propeller, the edges of the blades look a little bit rough. You can hold the two blades against one another and sand the edges of both blades at the same time to both smooth out the shape and make sure the blades are identical - I realize that prop is already assembled, but just for future reference.

Best of luck!


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 20, 2015, 10:37:55 PM
Hi Twinchicky,

Did sand the edges with blades together. Not enough from looks of the finish. Was in a bit of a hurry. Patience is the name of the game in indoor ultra lights.
Have used mylar which I first got from freedom flight models. Have used it on my hangar rat, Biscayne baby (nice LRS), Double Whammy and my A6. Mike Woodhouse also supplies mylar of different thickness - 1,2 micron etc and is cheaper too.
Need to get fresh stock to use on models being made now with my own lighter propellers.
Pic of my A6 with mylar.


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 21, 2015, 12:09:40 AM
Hi Twinchicky,

Here is a link if my mylar covered Biscayne baby in flight. Can increase duration by giving more winds. Had only about 300 turns on this one.
https://m.youtube.com/watch?v=DqRpv1k-ENI

Anant


Title: Re: Propeller for "The Fly"
Post by: Twinchicky on October 21, 2015, 12:30:53 AM
I like it! Now imagine the combined beauty of the mylar covering plus a lightweight balsa prop and a much, much longer motor. That will make your times soar.


Title: Re: Propeller for "The Fly"
Post by: Glidiator on October 21, 2015, 01:26:15 AM
Hi Twinchicky

Yes that double digit duration is the dream.