Sopwith Batboat

[lincoln]

It's impressive that such a detailed model can fly so slowly. Did you fill it with Heli-Spheres®?  ;-)

[g_kandylakis]

   

Thanks lincoln, no, I ran out, need to find more of them...

Thanks to the rest of you too for your nice comments.


I see now my last post here was 20th of April...

Well, the BMFA Nationals are history now and the Batboat was a no-show. A welcome unexpected trimming oportunity presented itself on Friday evening before the Saturday competition, so I took the Batboat for testing only to discover that the elevator control wires had gotten very slack, giving me virrtually zero elevator control.

This was somehow corrected back at the hotel but another issue arose, not enough power. I tried everything but could not get it to take off.

Eventually I decided to enter my 504 "O" instead, which proved a handfull to fly and provided plenty of excitement but not a very good flight score, still good enough for 3rd place    .

After some clear thinking and checks back home, I traced the problem to the motor base having come loose and allowing the brushless motor to come in contact with something that was keeping it from higher rpm. An additional screw corrected that, so now it is behaving again.

Duration is still rather limited as can be seen from the video, but a slightly higher Voltage battery seems to have solved this, from 2 minutes to 3 minutes, at a small weight penalty of 1,5 grams. But it does fly and quite well, so, waiting for next year now.

As for the photographs, the first three are from the (almost) finished model.

And the fourth, well, lets use it as a quiz. What can it be and mean? Anyone else "been there, done that"?

[ramses]

And the fourth, well, lets use it as a quiz. What can it be and mean? Anyone else "been there, done that"?

I'm guessing the effect of the motor (propeller) rotation direction was negative, and you are now going to test with a counter-rotating motor and therefore also need a counter-rotating propeller?

Or... you are going to couple two propellers for more thrust. More diameter isn't possible due to the construction of the tail, but more blades are?

Like on this Dornier Wal:



Cheers, Ramses

[ramses]

It could be the double propeller,.. i found this photo from a bat boat with a 4 blade prop:



Cheers, Ramses

[g_kandylakis]

Hi Ramses,

No...

Here is a hint: you are thinking too seriously...

And obviously by your replies you have never done that...

George

[Squirrelnet]

Very impressive George, it looks great in the air and has a good slow speed too.

Having seen this model up close it is almost unbelievable in it's detail and now it flies beautifully as well

[TheLurker]

Wot Squirrelnet sed.

[Lastwoodsman]

Wed May 20 2026

Hi George.   Great Batboat.

     My guess is that those two props are both one piece  "Chauvierre Integralle" props,  that were cut down and then waterlogged and then dried in a mold for the extra curvature in the blades ...

Pic #1   3575  Spad 7  with two piece "Chauvierre Integralle" prop.

Possible use ?    the Fokker D.XXIII ?   Just guessing, ...  I can't picture it ...   

Lastwoodsman
Richard

[Anyun]

I guess you carved the blades of the first propeller for the wrong rotation direction, and had to make a new one. It can easily happen, especially for pusher props (and yes, I've done it too...).

It's really a splendid model, and the pilot looks very realistic as well. Is it carved from styrofoam?

[g_kandylakis]

And we have a winner...

I have been researching the Batboat for over 20 years. After I built my first one in 2004 I realised that the initial drawings I had were wrong, so I set out to make my own set and have it approved by the BMFA for contest use.

During that process I got a remark that the propeller rotation direction was wrong. I checked with the photographs and indeed it was, so I corrected it on my drawings.

A few months later I was finishing the model and I also needed a dummy propeller. I had one already from my 2004 model so I used it, having forgotten about the drawing change. Besides, who has time...

At the BMFA indoor scale nationals, as I wrote before, I did not enter the Batboat. I did ask the static judges though, Mike and Phil Smith, if they wouldn't mind giving it an unofficial static judging to find out errors and points of imporvement, which they did.

And their first comment was "we think your scale propeller should be rotating the other way around"... Rather an embarassing error to have to accept. Even more as the person doing the drawing validation was Mike Smith himself, so I got the same comment twice.

Which is fine and can happen, only for me this was the second time it happened, same with my Avro monoplane back in 2013... I really need to pay more attention to that in the future   

So, anyway, a new one had to be carved. Needless to say, the first basswood block I started carving was thrown away, because it was again in the wrong direction. After extreme care, I managed to get the correct rotation. Live and learn?


Richard, Ramses, you both tried to find a real serious reason while it was simply a silly error on behalf of the builder .

You should know me better by now

George

[g_kandylakis]

... and the pilot looks very realistic as well. Is it carved from styrofoam?

Hi Andrea, late reply to your question about the pilot.

No, it is molded using polyurethane foam, using a silicone rubber mold.

More details here, in a separate thread:

https://hpa.aeromodelling.gr/index.php?topic=355.0