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Author Topic: Frog Chipmunk  (Read 6065 times)
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OZPAF
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« Reply #100 on: April 18, 2013, 08:13:10 PM »

I can't see any wonky bits Jon -  those pics must be very artfullly taken Grin. Do you run the paper grain spanwise or chordwise on the wings? its hard to see much sag between the ribs.
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Yak 52
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« Reply #101 on: April 19, 2013, 05:01:01 AM »

Thanks John. The grain runs spanwise but I covered the top surface wet and got it on pretty tight. Too tight probably but the structure is very solid and it's held it's shape so far.

Not sure what mine will weigh yet Dave, but roughly the same or a bit more.

Jon
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Yak 52
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« Reply #102 on: April 20, 2013, 05:11:24 AM »

Done  Cool

Weight came out as 26.5g before nose weight. It will need a gram or two to get the cg right but a lot less than I expected. The card is heavy stuff, the cowl weighed 0.75g. I normally avoid card by replacing it with thin balsa sheet but I've quite enjoyed using it on this model. Nearly all of it is ahead of the CG anyway.

All up flying weight will be about 32g giving 0.53g per in^2.

The wheels are a bit big for true scale but that's what's shown on the plan. I might make some smaller ones for after the Nats.


Here's a few pics...


Jon
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« Last Edit: April 20, 2013, 06:13:27 AM by Yak52 » Logged
DaddyO
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« Reply #103 on: April 20, 2013, 05:20:30 AM »

Terrific lookin' model Jon - well worth some kudos  Cheesy

Cheers
Paul
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Pete Fardell
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« Reply #104 on: April 20, 2013, 05:45:54 AM »

Beautiful! Put that man on the list. Smiley
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Yak 52
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« Reply #105 on: April 20, 2013, 08:23:51 AM »

Thank you gentlemen.

Mini-glides in the garden (blankets over the long grass I should've mown) proving heartening. About 1-1.5g noseweight. No wing drop in the stall too, which was my main concern.
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Dave Crompton
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« Reply #106 on: April 20, 2013, 09:17:26 AM »

Hi Jon,
what a stunning model!! it just shows how good a model can be finished just using coloured tissue and no paint.
Can't wait for tomorrow. I'm going on the fields at the back of my house later wind permitting to see if I can improve my flights on my two a little better as I won't have much time to do much trimming tomorrow.
Once again Jon, a beautiful finish, well done!!
Dave. Shocked
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OZPAF
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« Reply #107 on: April 20, 2013, 08:53:13 PM »

I can only agree with every one else - inspiring work Jon. Good luck with it.
As a covering dumbo - am I correct in thinking that you covered the wing wet using dope as glue?
Not a sign of a warp either.
You may get close to being banned then what Grin
John
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outofbalance
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« Reply #108 on: April 21, 2013, 08:47:40 AM »

I painted a prop for the first time too. This was a blue peck that was balanced and sanded then sprayed with 'flat black'.

Hi Yak52,

How did you fit that spinner so well (around the Peck)?

Very nice model!

TIA,

Outofbalance
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Rich Moore
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« Reply #109 on: April 21, 2013, 04:45:56 PM »

Congrats Jon! Not bad for your first entry, eh? Thanks for your help earlier. Panic is now over!
Rich
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Yak 52
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« Reply #110 on: April 21, 2013, 05:32:39 PM »

Thanks guys. No probs Rich - just glad you got your documentation sorted.

Outofbalance, the spinner is turned on a drill from balsa. A hole is cut in the back with a drill bit (a dremel would be better) Then the slots for the blades are cut carefully a bit at a time. The prop hub was cut down quite a bit and a new clutch cut into it. The spinner is not actually glued on. I spread canopy glue into the slots and when it dries it's tacky enough to hold the spinner with a 'friction' fit. I'll take some pics of it at some point.


You may get close to being banned then what Grin

Not even close John  Smiley The Nottingham boys have the flying side of things very nicely sewn up  Smiley Really superb flying.
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Russ Lister
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« Reply #111 on: April 21, 2013, 05:40:20 PM »

I would argue with that Jon .... I think the results were a true reflection of events .... and if I remember correctly 5th isn't that far behind 3rd! You were close behind!
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« Reply #112 on: April 21, 2013, 05:53:10 PM »

A good show John, your flights were impressive. I enjoyed seeing your chippie from initial hops to final trim......

Plus the cool walk away......

Andrew
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Pete Fardell
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« Reply #113 on: April 21, 2013, 06:03:27 PM »

I would argue with that Jon .... I think the results were a true reflection of events .... and if I remember correctly 5th isn't that far behind 3rd! You were close behind!
Quite right Russ. Only 13.5  points in it for the top 4. Great stuff Jon!

(pic attached, but you might go blind trying to read it)
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Rich Moore
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« Reply #114 on: April 22, 2013, 04:44:45 AM »

I thought you had it in the bag Jon, but then I didn't see any of Dans flights as that was my 'ready' time - I was furiously winding turns with my winder which only has 1:3.25 ratio! Your flights were superb. Just stay away from that bl**dy wall next time...
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Yak 52
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« Reply #115 on: April 22, 2013, 04:46:21 AM »

Ha yes. Note to self: make two spinners  Roll Eyes

Dan, Andrew and John C were really tough competition on the flying. Extremely smooth and slow scale speed. Very impressed with John as he hadn't had a lot of trimming but nailed it early on. My climb was too steep really - If I'd had another session I might have stripped a thinner motor.

Turns out the 'walk away' wasn't so cool. Briggsy advised staying put to avoid turbulence which worked better for me on the last flight.

Looking forward to the videos...
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Dave Crompton
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« Reply #116 on: April 22, 2013, 05:14:39 AM »

Hi Jon
Just to say well done yesterday mate, your Chippie looked and flew beautifully. I managed to get my yellow Chippie behaving at last yesterday and I think it flew better that my RAF one!! Maybe I'll build another for next year, who knows??  Anyway, well done again mate and it was nice meeting you.
Cheers, Dave.  Grin
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Pete Fardell
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« Reply #117 on: April 22, 2013, 05:22:01 AM »


Quite right Russ. Only 13.5  points in it for the top 4. Great stuff Jon!

Had it in my head you were 4th. Meant to say only FOURTEEN points separated the top FIVE! Anyway, top job! Video about to be put on Youtube. I'll put the link on here.
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Pete Fardell
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« Reply #118 on: April 22, 2013, 06:02:04 AM »

Here it is, and Dave's as well. Sorry, not a great vid with my little camera, but shows how smooth they were: http://www.youtube.com/watch?v=V5u1u5hDx3U
« Last Edit: April 22, 2013, 07:27:15 AM by Pete Fardell » Logged
Pete Fardell
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« Reply #119 on: April 22, 2013, 06:45:17 AM »

Just realised yours is a Frog not a KK  Embarrassed. Have amended Youtube vid now.

Spent all day thinking yours and Dave's were the same kit. Shows how much attention I pay!
« Last Edit: April 22, 2013, 07:29:40 AM by Pete Fardell » Logged
Yak 52
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« Reply #120 on: April 22, 2013, 01:53:22 PM »

Good to meet you too Dave. I saw some very nice flights with the yellow one in the other hall.


Thanks for the vid Pete  Cool


I would also like to thank John Barker (Hepcat) who indirectly helped a lot: with only Sat evening to trim I used the Prop Picker program to predict the motor and turns needed. On the strength of that prediction I secured our clubs rubber stripper and got some 5/32 stripped and made up motors beforehand. It worked perfectly first time and I stuck with that size. So thanks for an awesome bit of kit John  Smiley


Jon
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Yak 52
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« Reply #121 on: May 15, 2013, 02:38:51 PM »

I had a bit of outdoor flying with this model last week. It flew very well in spite of a bit of wind and managed a proper wheels on landing on the grass. Not really surprising since at the Nats it didn't so much land as fly onto the ground.

In order to tie up some loose ends here are the videos that have appeared to add to Pete's above (for my own reference as much as anything) Thanks George, Robert, Mike and Rich.

http://www.youtube.com/watch?v=S8WJL7Si8Kk
http://www.youtube.com/watch?v=Cqw51dHsyaA
http://www.youtube.com/watch?v=s3oJ3u2S1VM
http://www.youtube.com/watch?v=OCdPnW3-nrw


...am I correct in thinking that you covered the wing wet using dope as glue?
Not a sign of a warp either....

John, sorry I missed this. Yes, dope and thinners works very well on wet tissue. I just place the tissue panel where I want it, wet it with a large paintbrush and then smooth it out while flooding thinners through to activate the dope. Once its on and dry the edges are cut and tidied up with more dope. I did get a little blush but this lifted off with thinners on a tissue.

There were no warping issues but that is largely due to the chunky structure. I'm going to experiment with using pre-shrunk to take some of the viciousness out of it for lighter structures.

I did warp in some wash out - more on the right, outer wing than the left wing to give some right rolling effect 'to keep the wing up'. This and the masses of dihedral seemed to work with no slip 'n' slide on the climb out. The large moveable elevators were a real pain, being very sensitive. Just breathing on them was the difference between full stall and tail slide from the ROG or no take off at all. After a while I CA'ed them in roughly the right spot (about 2mm of up elevator) added nose weight (no ROG) and then removed it bit by bit until I got the climb as shown in the videos. I did loose 5 marks due to the separate control surfaces which lost me one place over all, but I don't think I could have got it flying so well without them. The decalage built as per the plan was too small, forcing fast trim speed or low stability with a rearward CG. Adding a couple of degrees negative to the tail would have been worth it.

I had built in a fair bit of right and downthrust but the model could have done with a lot more for consistent circles. I just relied on the size of the hall to allow for the opening turn. I did hit the wall twice (once on an official flight) but that was due to starting in the wrong place (And I have a reputation to keep up  Grin) The first time was on Sat and I broke the spinner. I repaired and repainted it over night but it looked pretty ropey. I'll bring two next time  Smiley

I've posted a couple of pictures for OutofBalance.


Jon
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Yak 52
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« Reply #122 on: May 15, 2013, 02:49:14 PM »

I also got chance to make an introduction on Sunday...
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« Reply #123 on: May 15, 2013, 03:39:44 PM »

Ah, big brother, little brother!

Nice pics Jon. Grin

Andrew
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Pete Fardell
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« Reply #124 on: May 15, 2013, 04:05:51 PM »

I love those model on the real plane shots, especially that first one. Now if you could just get a cute little chipmunk of the furry kind to perch beside it too, that would really be a picture!  Grin
(maybe wearing goggles?)
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