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Author Topic: Albatros D.III, Aerographics kit  (Read 13459 times)
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Tommy Wee
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« Reply #175 on: March 03, 2016, 07:18:16 AM »

Thanks David.

I intend to clean up the area round the hub, there really is too much balsa there. Improves appearance, too.
Already cut it, some sanding still to do. Thought also of rounding the prop tips a little bit more.

Tommy
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DavidJP
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« Reply #176 on: March 03, 2016, 07:49:26 AM »

Yes, Tommy, now I think about it of course you would be doing so - knowing your keenes for "looks".  Sorry!
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Tommy Wee
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« Reply #177 on: March 03, 2016, 09:27:54 AM »

No need to sorry, you were the second one to mention it to me Wink
This is after all the time when short-cuts might be made, as the plane nears final stages...

Some rough sanding and carving done. More like it should be now?
Round out the tips more?

Tommy
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Pat D
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« Reply #178 on: March 03, 2016, 09:59:34 AM »

Tommy

That looks Great !
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billdennis747
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« Reply #179 on: March 03, 2016, 11:52:06 AM »

If it were me, Tommy, I'd keep going! A strong hub is no bad thing but the blades should be perfectly flat on the rear surface from LE to TE, and the upper surface given a proper section, no more than 1/8" thick, thinning down to the tip.
I would concentrate on strength and efficiency because I would be making a scale prop  for appearance. Flying props never look good, and certainly not on a model as nice as this.
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DavidJP
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« Reply #180 on: March 03, 2016, 12:29:45 PM »

That will do nicely Tommy!

I think Bill has a point about scale props for static judging of course.  But yours will look pretty good.  Not known one to break near the hub in fact usually half way along the blade or the tip.
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billdennis747
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« Reply #181 on: March 03, 2016, 01:09:15 PM »

Not known one to break near the hub in fact usually half way along the blade or the tip.
Here's one I broke earlier!
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Tommy Wee
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« Reply #182 on: March 03, 2016, 01:34:57 PM »

Thanks for the advice!

I sanded some undercamber underneath, around 1/32" at tips. Was not sure if I should make a flat bottomed airfoil or cambered one. The upper surface is sanded to a section or at least I tried to! Thins down to tips at least.

Any advice on the airfoil? Plastic prop is thin and has undercambered profile, but I've seen all kinds of props and probably read too many aeromystical stories so now I am a bit confused. Willing to make a new propeller if convinced I am making things wrong here Wink

I'll probably won't do a static prop for this, as there are no competitions here for kit scale. Doing one might still be good practise...

Tommy
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billdennis747
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« Reply #183 on: March 03, 2016, 02:06:45 PM »


Any advice on the airfoil? Plastic prop is thin and has undercambered profile, but I've seen all kinds of props and probably read too many aeromystical stories so now I am a bit confused. Willing to make a new propeller if convinced I am making things wrong here Wink

I'll probably won't do a static prop for this, as there are no competitions here for kit scale. Doing one might still be good practise...
Tommy, as long as the section is thin, maybe max thickness at 30% chord, it's fine
I wasn't thinking about competitions for the static prop, I just think it finishes the model. After all, nobody just sticks on any old wheels.
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ironmike
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« Reply #184 on: March 03, 2016, 02:25:36 PM »

I would thin, and taper the blade a lot
but don't worry about any undercamber.
Helix yes.
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Tommy Wee
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« Reply #185 on: March 03, 2016, 03:03:16 PM »

Thanks for the advice Mike & Bill.

Was going to do a 190 mm propeller anyway, with fewer laminations. I'll make that a flat bottom airfoiled one.
Might even try both out both props made, will see.

Will do a static prop, too. With a separate noseblock for it, not a big job. At the moment Albatros is nestling on top of the bookshelf and as it is there most of the time a scale prop would look nice on it. Hadn't thought it that way, one thing more I have learned here!

Any ideas on a free-wheeling device?

Tommy
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« Reply #186 on: March 03, 2016, 03:47:15 PM »

Hi Tommy.  There was a lot of discussion about free wheel devices over on the Reverse S Hook thread in Buy Sell Trade.  The Garami type freewheel and the loop and clutch dog system are most common with wooden props however.  All work well but in my humble opinion they all work most reliably if you solder a washer on the shaft behind the prop so that the rubber tension is taken on the washer and not the prop.  This ensures that the prop will freewheel and not be jammed by residual rubber tension after the run.  There are illustrations on the thread I mentioned to show what I mean 
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billdennis747
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« Reply #187 on: March 03, 2016, 04:03:57 PM »

Hi Tommy.  There was a lot of discussion about free wheel devices over on the Reverse S Hook thread in Buy Sell Trade.  The Garami type freewheel and the loop and clutch dog system are most common with wooden props however.  All work well but in my humble opinion they all work most reliably if you solder a washer on the shaft behind the prop so that the rubber tension is taken on the washer and not the prop.  This ensures that the prop will freewheel and not be jammed by residual rubber tension after the run.  There are illustrations on the thread I mentioned to show what I mean 
Agree. If you look at the picture on post 181 you can see a nut between prop and bearing, soldered to the shaft. It's vital, and I've never had any success with the freewheels moulded into plastic props for that reason
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DavidJP
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« Reply #188 on: March 04, 2016, 04:06:29 AM »

Yes - clearly when you think about it that is the way to go.  Thank goodness for boffins!
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Tommy Wee
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« Reply #189 on: March 04, 2016, 11:23:29 AM »

Thank you all, especially Mike!

The drawing is clear to me, a good design. I've had trouble with free-wheelers before but the one shown looks very good. I try to replicate it at home or send an order to Avetek  Wink

Nice kits by the way. The modified plastic prop is also a stunner, a complete change from stock to something much better.

Tommy
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DavidJP
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« Reply #190 on: March 04, 2016, 01:00:07 PM »

Good to hear about flat section.  I have always had the undercamber because all props seemed to have it! But makes life a bit easier.

You did a good job on that prop. Bill.  Mind you with an impact like that it would have broken somewhere anyway.  Was it repairable?  Seen it done a couple of times. Needs must and all that.
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Pat Daily
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« Reply #191 on: March 04, 2016, 01:04:01 PM »

Tommy

Volareproducts.com have some great how to dos on prop freewheelers.

http://volareproducts.com/?page_id=1686
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« Reply #192 on: March 04, 2016, 03:51:32 PM »

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=19010.0

Tommy, I respectfully offer a design of my own that may help.... you need to do a little soldering...my soldering is better than what you will see here but you might get the idea. I usually conceal this affair in the nose cone. Anyway it works quite well for me on planes such as yours.... check replies #17 and 18
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Tommy Wee
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« Reply #193 on: March 05, 2016, 02:40:08 AM »

Thanks Pat and Crabby.
A good link to a treasure dove of information and a neat/simple free wheeler.

Tommy
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« Reply #194 on: March 05, 2016, 08:00:49 PM »

I wanted to weigh in here.  I've carved several props but not for scale, I've carved a couple Gollywock props and a Coup d'hiver prop, both folders, under the tutelage of some veteran free flighters when I lived in Seattle.

Undercamber is probably preferable. 

The recommended approach:
* Cut the blank to shape but don't cut the curve of the tips of the blades yet
* Carve the bottom surfaces of the prop first.  At this stage it's flat
* Use a rounded sanding block to sand in the undercamber.  This gives you uniform camber on both blades
* Now carve the top surfaces.  This is where the thinness of the airfoil is defined.  (Blades are now as thick as needed for strength but also thin for efficiency)   
* Round the tips as desired

Marlin
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Tommy Wee
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« Reply #195 on: March 07, 2016, 08:02:06 AM »

Thanks for the input, everyone!

First propeller is sanded now, weighs 3 grams. Feels very sturdy this one. Missing still a prop axle tube (plastic or aluminium) and a few coats of dope. I also intend to do add a plate representing the scale propeller hub with bolt heads etc. Won't weigh much, looks nice. Will make a slightly bigger propeller from lighter balsa, just to check the weight difference.

Wanted to try the Avetek style freewheeler, so I ordered a couple s-hook kits from NZ. Like the idea in it, propeller itself stays clean with no added tubes etc. Ordered also the Tiger Moth kit, it looked so nice...

Tommy
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DavidJP
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« Reply #196 on: March 07, 2016, 08:31:07 AM »

I think you will like the Tiger Moth Tommy. Your kind of model but no engine exposed of course - well only a little.

I could send you a copy of the article by Mike (Bristol Scout) on how he finished it if you like that appeared in  Aeromodeller not long ago.  I have an idea too that Bill did a review in AM.  The instructions can be downloaded and are superb.  "How to" is in the kit. 

I have your email address I believe.  Let me know.
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« Reply #197 on: March 07, 2016, 02:08:17 PM »

I'm sure you will enjoy the Tiger Tommy. Every one that I know of that has been built has flown well.  I have 2 of them that I built for Avetek as prototypes.  My original red one (which is built as kit scale and not serious scale) went out for an airing on Sunday.  In the damp air and with sopping wings we were getting around 42s.  Then when it warmed up I was getting 58 - 59s but couldn't quite crack the minute.  For the last flight I piled on 1800 turns which was enough to get it well away from the ground and then I hit some good air -1 minute 24s.  I'm still amping out about that!  So much for draggy biplanes!!
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Tommy Wee
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« Reply #198 on: March 13, 2016, 10:36:10 AM »

While waiting for the s-hook and parts from Avetek I carved a second propeller, just to try out a different darker dye and also lighter balsa with fewer laminations.

Not so sure about the end result. I like the looks of the first one better but the new one looks good, still. Made a flat bottomed airfoil to the new. The new one is 190 mm diameter, other one 184 mm so there is not a big difference.

Weights: light coloured, 10 laminations, 3.2 grams. Dark dye, 5 laminations, 2.3 grams. Percentage wise a big difference, otherwise not  Wink

Waiting also for the pilot figure from Mr. Banks. Will probably still make one myself, with help from Mr.Crossley's instructions and with the Banks example on hand.

Tommy

P.S. Thank you David for the Tiger Moth article offer. I am interested in it!
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« Reply #199 on: March 18, 2016, 02:28:15 PM »

Hi Tommy, what progress?  Did you get your items from Avetek?
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