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RM276 Chipmunk

RM276 Chipmunk

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Bob Webster24/08/2009 21:34:11
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62 forum posts
7 photos
Has anyone built this model recently?
Is it a good plan?
Does it fly well?
What engine did you use?
Does anyone have the original article? Is it available from MyHobbyStore?
I've always had a hankering after a Chippie and this one seems to fit the bill sizewise but I would like to hear some comments about it.
Bob W
Bob Webster04/09/2009 16:21:50
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62 forum posts
7 photos
All right, no replies.
Ordered the plan and canopy anyway.
Couldn't order a photocopy of the original article - Myhobbystore doesn't have an index of when plans were published.
Can anyone give me a date for the Radio Modeller which the Chipmunk appeared in please?
It would have been early to mid 1980's
Cheers
Bob
Danny Fenton11/09/2009 23:53:27
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5903 forum posts
2250 photos
Sorry Bob don't know the plan. I am surprised nobody has chipped in? (sorry couldn't resist the pun).
 
What size is RM276 ? I do like the Chipmunk, must do one...... one day
 
Cheers
Danny
kc12/09/2009 01:41:53
2652 forum posts
114 photos

 
It was  June  1984,  I have the mag somewhere.  I will find it in a day or two.
 
I remember a fellow club member saying there were some errors on the plan, ( perhaps the wing panels were different sizes, I cannot remember exactly ) but I am sure he overcame these and it flew OK.
kc13/09/2009 11:30:48
2652 forum posts
114 photos
I have the magazine.  It is 82 inch    1/5 scale for 60 two stroke or 90 four stroke and it is said to have exceptional low speed flying capability.  3 degrees of washout.
Jim Carss14/09/2009 14:01:32
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1541 forum posts
Bob,
Flew the Chippie for the first time a couple of days ago and it went very well although under powered with old ST 75,it only needed a click or two of elevator trim for straight and level flight.
when I have time i'll fit  ASP 91 fs  and recover it,as you know its been lying in the garage for years , your PM must have provided the inspiration to give it a wizz.

 Jim
Bob Webster21/09/2009 22:25:47
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62 forum posts
7 photos
Danny
Horrible pun but not unexpected - I forgive you!
The chippie has a span of 82" - 1/5 scale and should have a bit of presence in the air.
Kc
Thanks - bought a copy of the mag from magazine exchange. Makes an interesting read.
Jim
I am chuffed to bits for you - no use keeping aircraft lying in the garage, much better to get them into the air! It looks really good in the photo.
Having looked at the size of my SC 91 FS against the plan, I had started thinking about fitting a Laser 150. After reading your reply, I think that is what I will do - there's plent of space in the cowl. The polystyrene cowl which I was supplied with will get reinforced with GF and epoxy resin, otherwise I don't think it will last very long.
I have made up a set of wing ribs and cut the slots for the main spars.
Rear spar slots next.
Bob

Edited By Bob Webster on 21/09/2009 22:28:15

Jim Carss03/10/2009 11:13:30
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1541 forum posts
Bob,
sorry for the delayed response,Just come back from holidays.
 
Laser 150 will certainly do the job and eliminate the need for church roof up front,my cowl is firbre glass,they must have changed their supplyer since I bought mine.
 
keep me informed of progress
 
JIm 
Bob Webster05/10/2009 15:28:08
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62 forum posts
7 photos
Hi Jim
Hope you have returned fully bronzed and raring to put the Chippie through its paces.
I think a lot of the cowls are polystyrene now. This is a pity because in this size of a model polystyrene is next to useless. I am planning on epoxy glassing the fuselage and can reinforce the cowl at the same time. I quite like the surface obtainable from epoxy/glass - it is excellent for applying paint to.
The slots for the main spars did not agree with the plan for the wing and I had a fair bit of adjustment to make to the outer ribs. I then marked and cut the rear spar slots from the plan which turned out to be a good idea.
Port wing is on the building board and is being webbed slowly - one of my least preferred jobs!
No rush anyway since I won't be able to spray paint it until next spring when the weather warms up my garage to allow the paint to flow.
Did you need much of the old church roof up front? It doesn't look as though it will need as much as a Spitfire - my first Mick Reeves 74" needed 1.5 pounds with an OS 91 Supass. What a job that was to fit. The replacement needed much less with a Laser 150 up front - it's flying really well.
Cheers
Bob
 
Jim Carss06/10/2009 18:24:29
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1541 forum posts
Bob
With a Laser 150 up front you may not need any ballast at all just bear in mind to keep the tailend light as possible.
 
Regarding the plan,the wing is complicated as far as I can remember so take your time and as the old saying goes   measure twice and cut once.
 
I would use  4 servos in the wing instead of cranks.
I also think if using Laser 150 I would consider increasing the U/C wires to cope with the extra weight.
 
Jimbo 
TonyS06/10/2009 18:32:56
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1145 forum posts
323 photos
Jim,
That is a very pretty model.
Used to fly in these as a cadet from RAF Lynton on Ouse. I had a polish pilot take me through the up-draught from a power station cooling tower. It nearly ripped the wings off but what a ride - like being in Willy Wonka's magic lift  .
Anyway I digress. Would be very interested to know Bob how you get on with the build as I'm struggling through the build of a Yak 23 at the moment but that's from a kit not from plan and even that's giving me one or two 'challenges'.
Good luck and keep us updated. 

Edited By TonyS on 06/10/2009 18:33:44

Jim Carss06/10/2009 18:42:36
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1541 forum posts
Tony,
Thanks for the kind remarks,I built this model umpteen years ago and it lay in the garage all that time never flown,biggest problem at the time was its wingspan,couldn't get it in the car,every time I needed gear for a new project it came out of the Chippy.
 
It took Bob to provide the inspiration to get it flying and it goes very well but I need to fit my ASP 91 fs to give it some grunt.
 
Cheers
 

Jimbo
Bob Webster20/11/2009 20:36:27
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62 forum posts
7 photos
No building for a month or more - too many family commitments.
This week has seen the webbing on the left wing completed and the trailing edge fitted
The right wing has been brought to exactly the same stage.
Today I set up my dihedral board in anticipation of joining the wings in the near future.
Undercarriage blocks have been cut, routed and glued into place in both wings.
Feeling more positive about it now!
The wing is not a straightforward build nad a dihedralled building board is a must for joining the two halves. I will use 4 servos in the wing - I gave up on bell cranks years ago. Last model I used bell cranks on was my SA Bulldog - they worked well until the covering went on and the paint was applied, centring became the problem.
Cheers
Bob
PS Will probably build some more this weekend, judging by the weather forecast!
Jim Carss20/11/2009 21:16:28
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1541 forum posts
Bob,
 
Stick at it my man,I agree the wing is complicated,as I have said before the aileron / flap hinge alignment had me round the bend but we eventually got there.
I have the same problem regarding time at present,decorating etc,
 
my workshop is stripped ready for painting and its annual clean is under way .
 
First job on the Chippie when we get under way again is to fit ASP91 fs.
 
Stay cool
 
Jim
Bob Webster26/11/2009 15:36:21
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62 forum posts
7 photos
You're right there Jim, this is a slow build.
Every time something gets clamped into place there's no room to do any more!
Wings fitted on to dihedralled board and joined!
Idecided to split the dihedral brace into top and bottom halves and have fitted the top half. Much easier than trying to fit the huge things shown on the plan.
Have also revised the centre sectoion leading edge to make it more user friendly.
First wing skin fitted. Would have fitted the upper skin on the left wing but I've run out of round headed pins and can't remember where I bought the last box. They were particularly good because the heads were plastic and not glass.
Will leave the glue to set overnight and should manage the right wing tomorrow.
I really need an extra bench! Either that or I need to clear up the mess on the working bench.
Cheers
Bob
Jim Carss26/11/2009 16:05:16
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1541 forum posts
Bob,
 
Keep us posted,the end result will be worth it,when i get a round tuit i'll make a new canopy,aluminium framed in 3 pieces.
 
I'm need a few round tuits though.
 
regards
 
Jim
Bob Webster27/11/2009 21:21:09
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62 forum posts
7 photos
Upper skin added to left wing.
Ailerons and flaps cut off - only broke 2 ribs doing this - there's not a lot of rib left near the trailing edge.
Sand the rear of the wing and fitted the 1/8" trailing edge sheet which was a fairly easy job.
Cut out 2 rear dihedral braces from ply and epoxied the top one into place.
Left the glue to set.
Bob
PS Must add a few pics sometime.
 
Bob Webster28/11/2009 14:31:00
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62 forum posts
7 photos
I've set up an album for a few piccies of the build. Will add to it when I remember to take the camera out to the shed!
Bob
 
Bob Webster29/11/2009 18:57:15
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62 forum posts
7 photos
Wing centre section sheeted and all cap strips cut, sanded and glued into place.
Wing looking much better now in spite of looking like a pin-cushion.
Always amazed at how cap strips firm up the ribs.
Hopefully tomorrow I will lift the wing from the board and get the plan back.
I always find it very difficult to read the plan when it's covered by a wing - there's always a rib in the way of something important.
Bob
Jim Carss30/11/2009 10:20:36
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1541 forum posts

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