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Seagull 80" DH Chipmunk


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  • 3 weeks later...

Yay! I got the maiden and a couple of follow up flights in yesterday. She flew as sweet as all the others that have been posted here. The laser 120 is maybe a tad low on power for the vertical manoevres but looks a nice scale like combination none- the-less and needs a gentle dive to do a round loop. The wash in on the port wing has crept back in a little so she will stall to the left in an accelerated stall but she's predictable. Spins either way are good, and to the right enters a 1 turn spiral before the spin develops and stops within 1/2 turn when recovery is initiated. Maybe the Spin strakes are having some effect. I practiced the scale schedule plus a few extra attempts at spins and loops and found I still had 2/3 of a tankful left. Very frugal compared to the Gemini 160.

The only issue in the three flights was on the 2nd flight when a flap clevis (M2 metal) that pulled off the threaded rod but even then on the approach when full flap was applied I saw the flaps come down together initially then an un-commanded roll which was easily overcome by the ailerons followed by another as I raised the flaps but made a safe landing anyways with the port flap flapping in the breeze.

Now I have to find some threaded rod that will take solder as most of the rods I have are of Oriental origin and are non magnetic and don't take to solder.

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  • 4 months later...

So in preparation for scale competitions kicking off again I thought I better get my two Chipmunks ready.

The larger Black Horse Chippy got a new set of bearings in the motor, as well as a gyro. The 85" model flies on 5S2P 10000mAh (2 x 5000mAh in parallel). The current draw is around 65A so two fairly cheap packs will cope as its only 32A per pack.

 

For the 80" Seagull Chippy it got a new motor for this year, same spec, just a later version. This model is also now sporting a Gyro.

This model is on a single 5S 5000, so the quality of the cell does make a difference. For this year I have invested in a couple of quality Purple Power packs.

 

One thing I had to check was the c of g using the old packs, so that the 30g heavier PP's could be positioned to give the same c of g.

 

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So the Vanessa rig was set up and first the original pack, to find the current c of g and then check the pack position to give the same c of g with the PP pack.

 

Whilst I was working on the Seagull I thought I would add a little detail, nothing much, but I wanted exhausts.

 

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So, we are all ready to get in some practice flights ? (The cowl fit isn't usually that bad, I hadn't nipped up the cowl screws ?  )

 

Cheers

Danny

 

 

 

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Oh one more thing, I weighed the model again as there was some doubt over its weight.

 

It weighs: port 2006, stbd 2009, and tail 616. If my maths is right that's 4631, with 5S 5000 battery. The pack weighs around 600g, so the model weighs 4kg. (Remember I did make a new tail-plane and elevators)

 

Cheers

Danny

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  • 10 months later...

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?

Edited by Martin Harris - Moderator
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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.

 

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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

Edited by David Ovenden
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  • 3 months later...
12 minutes ago, David Ovenden said:

Successful test flight with the Chipmunk. I need to work on my 3- point landings though as this model seems quite prone to bounce on landing!

Thanks to Danny for the "671  lettering" that looks great.

 

You are welcome David, but where are the piccys?

 

Cheers

Danny

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