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Bleriot XI

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David Germany27/10/2016 18:36:03
82 forum posts
26 photos

img_20161027_1542464_rewind.jpgCan't help with prop selection Birgir, I tend to use trial and error. If you are thinking of using wood how about an XOAR WW1 Scimitar, I have one on my Flair Puppeteer and I think it looks better than the normal wood prop.img_20161027_1542038_rewind.jpg

Jon Harper - Laser Engines27/10/2016 20:23:17
3162 forum posts
129 photos

The trick with props will be to keep the rpm in the working range of the engine. In your video the engine seems to be really screaming but you aren't really going anywhere so that suggests it needs a bit more prop. If you have a tacho I would choose a propeller that runs about 9000-10000rpm on the ground. You don't really want it revving like mad as its not as efficient like that. The symptoms you mention about the engine are typical of an engine getting a little too hot but I would not be worried. cooling will improve in flight so if it hangs on for 10 seconds on the ground in the air will be just fine.

I used 10x5 master airscrew props with some success in the past and now the engine has some running time this might work well. 11x4 master or 11x5 turnigy A would also be worth a try. Its possible a 12x5 turnigy might work if they do one. The master props should be very cheap and easy to get and will be more robust during your testing phase.

Jon Harper - Laser Engines27/10/2016 20:46:42
3162 forum posts
129 photos

I just read your post again and I didn't really address one of your questions.

The simple answer is that there is no simple answer. Choosing a propeller is not easy and predicting its performance is also not easy.

For example, using my saito 45 for reference I recorded the following figures

13x5 turnigy type A - 8600rpm
13x5 turnigy cherry - 6200rpm
13x5 Master airscrew K - 7000rpm

Again, my Laser 180 recorded this:

Master classic 18x8 - 7500rpm
Master wood scimitar series - 7200rpm
Turnigy type A 18x8 - 8000rpm
Menz wood 18x8 - 7400rpm

So, not only is material a concern but so is the brand. In the case of my 180 the prop with the slowest rpm (master wood) was the one that gave the best performance. The Menz was next and then the turnigy and the classic fought over last place with the classic being very noisy. RPM is not everything and if the prop has no bite on the air then you will loose performance.

But

being able to turn a larger diameter at the same revs as a smaller prop will give higher thrust, so the type A series that normally run fast will usually give back more than they loose because of their inefficient blade. In the case of my 180 this didn't happen as I did not get enough of an rpm rise, but on the saito it worked very well as the rpm rise was so large.

As david has already said its about trial and error at the end of the day, and its about compromise. For example the lovely xoar he has on his pup there is not the most efficient as it puts a heavy load on the engine. That said, it looks great and while the engine might not give its best performance using it, if the performance is enough then its not an issue.

As I don't know how the props you are using perform I cannot really judge which brand would be a step up and which would be a step down. All I can say is that my old tiger moth flew well using the master 10x5

p1000902.jpg

Birgir03/07/2017 10:21:43
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129 forum posts
55 photos

Hi

The weather here in Iceland has not been very suitable for my Bleriot project lately. Never the less I’ve been able to do some flights. As some of the readers of this thread may remember there are two main tasks at hand at present. The first one is adjusting the CoG losing some of the lead up front and the other one is to select the best prop to be able to get the most out of the rather small SC30FS.

On D. Boddingtons plan the CoG is marked about 10 cm from the LE. To get the CoG to 11 cm I had to put about 600 gr of lead on the landing gear and therefore it was very difficult to get the model up to speed on the runway with the rather small engine. When in the air I had to use a considerable amount of up elevator to keep it level. I took Donald’s Fry advice and took off 25 gr of lead after each flight. Now I’m down to 425 gr so I must have had more than eight flights until now. The model still needs an up elevator, but considerably less than before.

During this time, I’ve only had two crashes, not counting some hard landings and minor injuries. Both was of course my own fault. The first one was fixed by re-gluing the landing gear but the latter one was more drastic. The reason for that crash was that once again I didn’t follow the rule of heading directly into the wind until suitable height is reached. If you allow the model to turn to early it will drop a wing and tip stall into the ground. (I needed three instances to get this; understand, practice and remember.)

20170629_162840.jpg

The model is already fixed and ready for take-off once again.

20170702_184949.jpg

I’ve been using 10*4 prop but as the engine runs in, it gets more power and I have now switched to 10*5 and by that I’ve got a little more speed for take-off.

It might be wise to try 9*6 or 10*6 as I could still do with a little more speed for take-off.

Now I´m off for Texas for a fortnight so further test must wait a bit.

B.

Note to moderator:
To my surprise this thread has had more than 10.000 visits even though it has been buried deep in the forum. I wonder if it is possible to see where the bulk of those visits come from. Is there some website with a lot of Bleriot enthusiasts out there on the internet?

Edited By Birgir on 03/07/2017 10:34:29

cymaz03/07/2017 11:05:14
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7096 forum posts
942 photos

20170702_184949.jpg

I’ve been using 10*4 prop but as the engine runs in, it gets more power and I have now switched to 10*5 and by that I’ve got a little more speed for take-off.

It might be wise to try 9*6 or 10*6 as I could still do with a little more speed for take-off.

Now I´m off for Texas for a fortnight so further test must wait a bit.

B.

Note to moderator:
To my surprise this thread has had more than 10.000 visits even though it has been buried deep in the forum. I wonder if it is possible to see where the bulk of those visits come from. Is there some website with a lot of Bleriot enthusiasts out there on the internet?

Edited By Birgir on 03/07/2017 10:34:29

I'm sure not only Bleriot fans read this but engine owners, builders and fliers who might learn something from reading the excellent blog

Birgir19/08/2017 22:04:41
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129 forum posts
55 photos

Now the wing is fixed and testing can go on. This time I used 10x5 prop and 425 gr lead.

The model still needs a bit up elevator to keep level and could also do with more speed. Later I tried 10x6 and 400 gr of lead but dropped a wing turning too soon and broke the landing gear. I ‘ve already started to fix that.

The flight in this video taught me to leave the phone in the car while flying.

B.

Edited By Birgir on 19/08/2017 22:14:50

J D 811/10/2017 23:18:46
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689 forum posts
50 photos

FLAMBARDS BLERIOT rollingFlambards Bleriot rolling

J D 811/10/2017 23:21:01
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689 forum posts
50 photos

After a long wait my Bleriot took to the sky once more.smiley

More info and pics soon.

Birgir11/10/2017 23:31:55
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129 forum posts
55 photos

Grate news, looking forward to more pics

B.

Jon Harper - Laser Engines12/10/2017 08:40:45
3162 forum posts
129 photos

I missed these posts until today. The model looks good in the air but i think your elevator rate it a bit too high. If you have a load of expo in it remove that as well as that could be the reason its porpoising on the landing approach. It also looks a tad tail heavy but you might get away with that if the rates are lower.

For propellers, dont use more than 5'' pitch as its thrust you need for that model and not speed. The higher pitch will give you greater speed, but only if there is enough thrust to overcome the drag of the model. If 10x5 is revving out well then try 11x5 as the next step.

Birgir12/10/2017 17:12:53
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129 forum posts
55 photos

Thanks Jon, I will keep this in mind.

Here is a video that John might like 😊

**LINK**

B.

Don Fry12/10/2017 17:48:48
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1871 forum posts
25 photos

Birgir, I would also leave the CG alone for the moment, and reduce the elevator throws a bit. Get used to it first, now it flies.

Jon Harper - Laser Engines12/10/2017 18:19:22
3162 forum posts
129 photos
Posted by Birgir on 12/10/2017 17:12:53:

Thanks Jon, I will keep this in mind.

Here is a video that John might like 😊

**LINK**

B.

ooo nice. You sure got that 30 sounding good

john stones 112/10/2017 22:51:13
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8856 forum posts
1379 photos
Posted by Birgir on 12/10/2017 17:12:53:

Thanks Jon, I will keep this in mind.

Here is a video that John might like 😊

**LINK**

B.

Magic yes

J D 812/10/2017 23:06:05
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689 forum posts
50 photos

That is a nice video Birgir.

Despite having the model ready at the end of last year things have conspired [mainly weather] to keep it on the ground until last Sunday which was cloudy but flat calm,Ideal conditions to test an edwardian era aeroplane.

This model was built some 40 years ago for the filming of flying shots for the TV series Flambards along with a number of other models and full size ground running replicas by David Boddington and his team. Model built by George Swallow I belive.

I had intended to add more detail and four stroke motor to the model but on discovering it's history decided to keep it as original as possible including the fitting of a Webra 60 from the 70's although with a modern carb and a home made exhaust to fit in the engine bay. I dont think any silencer was fitted filming they just dubbed on old engine sounds afterwards.

For the first take off I held in full up as I opened up the motor but pressure from the long tail on the skid half way down the fuzz made a good anchor in our rather soft strip but on its release she rolled away and rose into the sky with little input from myself. Soon I had to throttle back as it was climbing steeply,there was no shortage of power.

These early aeroplanes tend to be one speed machines with their lifting tails,to much speed and they start doing strange things [ not a problem for early airmen with the limited power availble at the time] A couple of circuits and motor in for a smooth touchdown. Brillsmiley

Had five more flights and as other clubmembers arrived they said they could not belive that the Bleriot could fly so slow and stay in the sky.

I tried a stall high up at low power but all it did was keep going in a nodding flight,It sometimes wallows in a turn but nothing to worry about.Shutting down to tickover results in more of a parachute decent than a glide.

J D 812/10/2017 23:19:00
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689 forum posts
50 photos

Up and away7.jpg8.jpg

J D 813/10/2017 08:22:55
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689 forum posts
50 photos

Fly pastFlambards Beriot

Jon Harper - Laser Engines13/10/2017 08:46:29
3162 forum posts
129 photos

thumbs up very nice

Birgir13/10/2017 09:04:58
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129 forum posts
55 photos

Looks grate and very well balanced in the air

Birgir13/10/2017 09:28:21
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129 forum posts
55 photos

Thanks Donald, I like your advice.

I will hold back on changes and practice with 10 x 5 and 425 gr.

The problem is though that the flying season is probably over here in Iceland for this year.

B.

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