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-   -   Heine replica (http://woodenpropeller.com/forumvB/showthread.php?t=2834)

maxim08 01-11-2014 09:32 PM

Heine replica
 
I'm a novice at propeller making but thought that I would show a few photos of my 3rd under way.

Each of these has been an airworthy copy of an original Heine prop for the high compression Daimler-Mercedes DIIIau motor as used in the Fokker D VII. While there are drawings around for a D VII prop made by Axial, apparently this propeller is preferred by 2 out of 3 Mercedes engine D VII owners.

The prop is 2.8m in length (110 inches) with a pitch of 2.1m.

The first propeller was all mahogany in 8 laminations as is my original. The current one has (back to front) 4 layers of mahogany, ash, mahogany and two layers of ash.

http://i109.photobucket.com/albums/n...psd2664b38.jpg

http://i109.photobucket.com/albums/n...ps730fa470.jpg

http://i109.photobucket.com/albums/n...ps2a4cf199.jpg

http://i109.photobucket.com/albums/n...ps9afd3e10.jpg

http://i109.photobucket.com/albums/n...ps492ccffb.jpg

Regards
John

Dave 01-11-2014 11:45 PM

Nice work. As much as I hate to see replicas replace the originals, it's always nice to see one well done, and airworthy.

maxim08 06-07-2014 08:26 PM

If anyone is interested, here's a photo of the final.

http://i109.photobucket.com/albums/n...pse360fac6.jpg

I'm 6' 0" for comparison.

Regards
John

Garuda 06-09-2014 09:58 PM

replica propeller
 
Hi John,

I think I saw a similar thread about your propellers on The Aerodrome. If I did not reply to your thread there I want to take this opportunity to let you know how absolutely impressive your efforts are! You say that you are a novice, which I am sure you are but your work is absolutely outstanding, and I am sure that professional propeller makers, if there are such craftsmen out there would agree. Building replica propellers, aeroplanes and other similar components is a lost art to a large extent, but efforts such as yours are very important in terms of keeping these skills current and reviving them where possible.

I've started (quite a while ago now! :oops:) a replica Garuda propeller for a 110 HP le Rhone / Oberursal, so I appreciate the time and effort which goes into these propellers. I chose the name Garuda for this Forum but for eBay and The Aerodrome I use the name '14-'18aviationcollector, or variations of it since it best describes my field of interest. I thought that the name Garuda was more appropriate for a Forum which specifically discusses propellers, but occasionally members might not make the connection.

It took quit a lot of detective work to figure out the species used in the original propeller and to source the same, or suitable substitute species. There are some issues such as the fact that Mahogany which is available for sale is grown in plantations now, so I am not sure if it is dense enough, but I will experiment with replica propellers and compare the weight to that of the original propeller.

Presumably you are using West Systems epoxy, which seems to be the popular choice worldwide, and I may have seen mention of it on your other threads. Here in Australia West Systems epoxy is available but we are very lucky to have an Australian made alternative, which is Techniglue. I have decided to use it, and I have been very happy with the ease it able to be worked with, the long, but not too long working time and the finished strength of it.

Did you clamp the laminations very softly or relatively tightly? I have been told that loosely clamped laminations are preferable, since if the glue joint is clamped too tightly it can remove far too much of the glue. I have clamped my glue joints far more tightly than I have seen some joints clamped, but I have tried not to overdo it, since I don't want the joints to be weak of course. To compensate for this I have used a very simple substitute for the toothing plane which was used on many original propellers, although not all of them according to other collectors and replica builders. I have subsequently been able to source toothing planes, so I will probably buy one when I can afford to do so. As I am sure that you know, any method of scoring the surface of the timber such as a toothing plane or the substitute I have devised increases surface area of the joint and greatly increases the strength of the glue joint, so I am very confident that my joints will be very strong. Perhaps in the future, destructive tests will prove to be very informative. For the meantime, simply building and using such propellers will reveal any faults, if they are present. I suspect that any modern epoxy glue joint will be far superior to the original formaldehyde glue joints, which by the way in most cases I have seen are still relatively strong.

I took the Garuda propeller over to Adelaide to show a few people a few years ago and I heard a very loud crack in the relative heat of the car, which was a glue joint partially delaminating, but even so, the propeller is still very strong and most of the joints have stayed together very nicely. In the future I will only travel with it in an air-conditioned vehicle, to avoid any further unnecessary damage.

Regards,

David.

maxim08 07-05-2014 02:11 PM

Hi David, nice to see you 'over here' on woodenpropeller.

Yes, that's me on the Aerodrome and much of the technique was shown there but I will do a quick recap for others.

Honduran mahogany is still available in Canada although a restricted wood in the US. It can be found masquerading as 'Central American' mahogany. I am fortunate to know a very good cabinetmaker who has helped greatly by selecting much of the wood for me. In Canada the difficult to get species is white Ash. A nation wide infestation of the Emerald Ash Borer beetle has decimated the species with massive culling and burning taking place in an attempt to slow down this invasive species from Asia. The next prop will use Birch instead of Ash, one of the traditional German prop woods.

I have been using West Systems 105 epoxy with their slowest hardener, #206. While WS recommend fillers be added for laminating, I declined due to the whitish colour that they add to the glue line.

I laminate on pair of boards at a time with a 24 hour cure between. It is slow, 7 days to glue 8 laminations, but it is safe and helps to ensure that each lamination is aligned correctly to the next.

The basic process involves wetting the back of the top lamination using a flexible autobody spreader to ensure an even coat. Next comes the bottom layer which is treated the same followed by re-coating the back of the top board. The WS eopxy has quite low viscosity and it flows out quickly and is absorbed quickly into the wood. That is the reason for the reapplication to the first board which ensures plenty of epoxy. The curse of laminating is a glue void. If you find one, the prop is scrap unless you plane off everything above and start over. Trust me, with the price of wood and the difficulty in finding boards large enough, I use lots of glue!

I have never grooved or deliberately raised the grain when making laminated wing spars, but the original Heines that I have inspected all show definite tooth marks between layers. Unfortunately no picture. What I used was a fine tooth dovetail saw that had symmetrical teeth ie identical tooth angle both directions. I grooved each board with overlapping strokes and quite a bit of force pulling the blade sideways toward myself. When grooved, I run a scraper lightly over to knock the peaks off the grooves as I don't want them to collapse into the grooves when clamped.

I use moderate/strong clamping force. WS does not have as good gap filling abilities as T-88 and by pre-wetting the boards I can avoid dry glue-ups.

http://i109.photobucket.com/albums/n...ps2a360ca0.jpg

The above clamping rig is really for clamping 28' spars, so the 2.8m prop is easy.

Note that I responded to your PM. I hope that the above is of interest to you even if it took me a month to see your note!

All the best,
john


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