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David Ovenden

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Posts posted by David Ovenden

    Seagull 80" DH Chipmunk

    in Scale and Semi-Scale kits

    Posted · Edited by David Ovenden
    picture

    12 hours ago, Paul De Tourtoulon said:

    loads of drawings available,,,,

     

     Here's a walk around, where they do look a bit bigger,,,,

    http://www.grubby-fingers-aircraft-illustration.com/Chipmunk_VH-RSK_walkaround.html

     

    Thanks Paul,

    Yes the wheels in that walk around do "look" bigger. It's surprising how small the wheel hubs actually are and how "chunky" the tyres look.

    chipmunk wheels.JPG

    Seagull 80" DH Chipmunk

    in Scale and Semi-Scale kits

    Posted

    The 

    9 hours ago, Martin Harris - Moderator said:

    Making a few assumptions and informed estimates, the model is 1:5.15 scale and the full size tyres (600 x 6.5) around 19” diameter so the model’s wheels should be 3.7” diameter (and 1.25” wide). 
     

    Therefore 3.5” wheels would be a bit undersize and 3.75” a little oversize but not by much. However, I can’t find any tyre profile information so the actual size could be an inch or two smaller. 
     

    The one thing I can say with confidence is 4” are right out!

     

    P.S. My 1/6 scale Airsail Chipmunk has 2.75” wheels which I assume were what was specified on the fairly accurate design for the scale kit (my plans are somewhere in the loft) which only equates to 16.5” diameter so the profile may be something like 85% as per traditional car tyres. Perhaps if you’re already using 3.5” wheels, stick with them for the time being?

    The wheels in the kit are 3.25" which is why they look "too small" to my eye I guess. I do have some 3.75" Robart wheels but they are too narrow in cross-section to look "right". I'll have to look around for something.

     

    What do you draw on?

    in Building from Traditional Kits and Plans

    Posted

    Technical Drawing was my favourite subject at school  and I did quite well at it. Until it was dropped as not being a "proper subject".

    Drawing my plans on tracing film(paper) with black ink. Bought a big roll cheaply from eBay as it had been opened and a few cms cut off the end of the roll. Lovely medium to draw on. And you can put outlines/shapes/ underneath and trace through.

    Prostate Cancer

    in Chit-chat

    Posted

    8 hours ago, Andy Joyce said:

    Disappointed that you need the catheter in for several weeks after a TURP which puts me off that approach. 

     

    Re the Tamsulosin I take it every other day and I do notice on the days that I take it that it reduces the need to go on multiple occasions so assume it is working. Was advised that it only works for about 6-8Hrs and takes ~4hrs to work so taking it latter in the day may prevent getting up during the night.  Didn't work for me though so just take it at random times during the day.

    My experience of having a TURP was very positive. I only had a catheter for 2 days after the operation whilst in the hospital. It transformed my life as I no longer had to get up in the night. Obviously everyone's experience and circumstances will be different. But for me the op was very successful and fast to recover from without any subsequent problems.

    Curtis Condor biplane twin

    in Building from Traditional Kits and Plans

    Posted

    1 hour ago, Martin Harris - Moderator said:

    Long shot but are all the servos digital?  I have seen the odd glitch from mixing servo types in the past.  Probably not an issue with modern transmitters but best to consider all possibilities before committing your hard work to the air again!

    Yes, all 4 servos are the same type. All JR digitals, all the same spec.

    • Like 1

    Curtis Condor biplane twin

    in Building from Traditional Kits and Plans

    Posted · Edited by David Ovenden

    1 hour ago, Martin Harris - Moderator said:

    Nobody's mentioned the possibility of a dodgy elevator servo as far as I can see. IIRC you had complained of occasional random trim changes in pitch which could be signs of an ageing feedback pot in the servo preventing accurate re-centring - maybe it finally bit big time...

    It's a good question Martin. But the servo is a new JR NX3421 x-bus digital that was and is working perfectly. 5kg torque is more than enough. There was no slop in the linkage either as that was checked prior to the crash.

    I think it may have been the gyro giving the odd trim change problem? 

    Curtis Condor biplane twin

    in Building from Traditional Kits and Plans

    Posted

    Hi Chris

    Thanks for taking the time to read the thread and to respond. You ask some good questions. To answer briefly. 

    The 5s Lipos, though new, were just very poor. Though labelled  as 35c they certaint aren't and voltage dropped drastically very quickly. Hence the ESC warnings.

    I swapped out the 5s lipo for 2 x 4s lipos (40c) which provided plenty of power for the plane and didn't sag under load.  So no more ESC warnings.

    The motors ran and responded perfectly at all times - never any lag or hesitaion.

    I was/ am using counter rotating 10x8 3 blade props which provided good power and with which there was negligible torque swing on takeoff.

     

    I think the problems with the model are mainly rigging/ incidence issues or a faulty gyro unit. 

    I am checking the incidences and adding washout. The gyiro is coming out.

    I will try it on one lipo pack to reduce AUW. We will have to see whether that improves things

    Curtis Condor biplane twin

    in Building from Traditional Kits and Plans

    Posted · Edited by David Ovenden
    Spelling

    Hi Jon,

    Thanks for the input. Yes, one engine out would have given that effect, but both engines were working fine before, during and after the crash.

    However,  thinking about it I wonder if the gyro was the cause of problems all along. Intermittent malfunctions could have given the weird and random unsettled moments I experienced before it finally went u/s.

    I will take it out competely and then I will know any weird flying characteristics are caused by the model not the gyro.

    Saving weight is one issue. Removing mass from the extremities(front and back of fuselage) is another. Should help the handling???

    I will also introduce washout on the top wing to help tame the plane.

    Prostate Cancer

    in Chit-chat

    Posted

    Martian,

    Really sorry to hear your PSA figures seem to be going in the wrong direction.

    Like you I was diagnosed with prostate cancer in April 2019. 

    Many of us are grateful to you for your courage in starting this thread and promoting discussion of this key mens' health issue. Will be thinking of you as you go for tests.

    Curtis Condor biplane twin

    in Building from Traditional Kits and Plans

    Posted

    I have finally got round to starting the repairs on the Condor model. I have sripped out the servos from the tail and removed any excess weight I could from the rear of the fuselage.  I have largely rebuilt the front fuselage structure and need to think about where to relocate the servos.  I want to squeeze the servos and ESC right at the front of the fuselage.  l wonder how much weight I will actually be able to lose? Will the model fly any better afterwards? Only one way to find out.

    • Like 4
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