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        Q&EFI '400' Spitfire Mk IX

#1 Andycart Feb 25, 2003 02:27 AM

Q&EFI '400' Spitfire Mk IX
 
Hi Guys

Is anyone planning to build the Spitfire in this month's Q&EFI? I started last night by transferring the plan to photocopy and then ironing the parts onto the balsa. I cut half a dozen ribs and then had to pack up for the night. This looks like a great model and it will be my first scale job.

Andy

#2 tim hooper Feb 25, 2003 02:31 AM

Andy,

I'm not planning one myself, but I seem to recall a thread about the its Hurricane sistership. Could be worth a search.

tim

#3 Craggsy Feb 25, 2003 03:51 AM

Andy,
What are the details? Built up wing? size ect. any photos of the plane. Q&EF is hard to get around these parts. I've just finished a Spitty and I think they look great in the air!
Dan.

#4 Robbie d Feb 25, 2003 05:44 AM

the span is 27 inches, quite small, must be a fast model. all built up wing with all up weight being ~14oz

#5 vintage1 Feb 26, 2003 04:35 AM

Magazine hasn't arrived in newsagents yet. I guess you guys are on subscription right?

I wasn't impressed with the hurricane. Seemed too much motor run too low on the power curve.

I preferred the all sheet spit from RCM&E.

#6 leccyflyer Feb 26, 2003 05:31 AM

Not on subscription (yet) but the magazine was in the shops here last Friday.

The Spitfire is a pretty small one at 27" span - that works out at 1/16.33333333333333 scale or thereabouts, so if you only construct your models to "proper integer" scale size then you would need to do some reducing or enlarging of the plan, oh and the wood, erm and the spinner might be a problem too- but you would be confident that at least the numbers match up ;). If you build your model to fly OTOH it looks very spitty like indeed.

The construction is 1/16th sheeted built up wings, 1/16th sheet fuselage sides, 9 formers, 3/32 longerons and all sheet tail surfaces, with full span ailerons operated by a single micro servo via torque rods. The prototype weighed 14 oz and at the time of the write up had only flown once due to weather. It doesn't mention if there is a cockpit canopy available from Traplet for this one. The battery is an 8 cell pack of 650mah AAA sized Nimhs. Looks very pretty in the photos, but no flying shots (other than one of the full sized MH434 taking off/landing).

Brian

#7 Robbie d Feb 26, 2003 05:46 AM

what about using a 280 of some sort and smaller cells to lighten things up, any ideas people?

#8 Mike Smart Feb 26, 2003 06:11 AM

Only to 14 decimal places Brian? Will that be accurate enough?;)

Mike

#9 Andycart Feb 26, 2003 06:23 AM

I wondered about the power setup as well. I think I might try it with a geared 300 or 280 and see how it goes. I don't have Motocalc so I can't run the numbers but I could power it with a couple of 560 mAH Kokams which would reduce the AUW considerably over the suggested 8 x AAA NiMHs.

I cut the rest of the ribs last night (yawn) and got the wing centre section built. So I've a long way to go yet but hey that's half the fun.

Andy

#10 vintage1 Feb 26, 2003 11:18 AM

Quote:

Originally posted by Robbie d
what about using a 280 of some sort and smaller cells to lighten things up, any ideas people?
Yes. My gut feel is a geared 280/300 maybe a GWS 300? would do nicely.

Oh well, I have a little time to kill, lets fire up motocalc....

On those weights and a guess at wing area, its 22mph stall!!! (hefty chuck that) but on 8 cells a very decent performance. I thought the Hurry was on 6 cells...but this is on 8. Much better. something like 600 fpm climb and top speed over 50 on the level maybe.

GWS 300 on 3.75 box and 7x6 prop is pretty good on climb, but no top speed.

Nope. I think the fact they have gone to 8 cells makes the difference really. My biggest beef on the hurrcane was that it was 6 cells only.

What is the wing area? I keyed in 112 sq in...

#11 Andycart Feb 27, 2003 03:46 AM

Thanks Vinatage1. I don't know the wing area off the top of my head I'm working away from home for a couple of days and I didn't bring the mag or the plan with me. As soon as I get home I'll have a look and post it.

Andy

#12 leccyflyer Feb 27, 2003 04:05 AM

Estimate the wing area at about 125 square inches- it's elliptical, 27" span, 6 " root chord, 5.5" at about 50% span and 3" at the tip rib before the wingtip. Using a simple ellipse and an online calculator that gives 0.86 square feet, but the shape may not be quite right, probably close enough though.

There must be a utility somewhere that you could stick a scan of the ellipse into and give you an accurate measure I suppose.

Brian

#13 vintage1 Mar 01, 2003 01:51 PM

Well got my copy today and have scanned it so I can plot as many copies as I want on A1 sheet :)

First impressions...not bad at all. Unusual battery pack - Overlander 650 or Sanyo 720mA/h NiMh. The speed 400 is caning that a fair bit, especially on a 6x4.

I ran some figures through motocalc, and the best motor apart from a small brushless seems to be the GPS 300C geared 2.8:1 on APC 5.5x2.5 prop.

Nice thing about that motor is it has a suitable spinner on.

Motocalc comes up with 525 fpm climb, 45mph level flight and a stall speed around 19mph. I estimated 140 sq in Brian :)

Plus WOT times of around 7 minutes. (5A draw) Gunther isn't too bad on that motor either.


The sp 400 and gunther gives similar results - a bit faster at about 47mph, but drawing 7A, which is pushing the pack a bit hard.

Sadly I neikther have a suitable motor or pack available, so I won't be rushing into building it immediately, but it looks like it should fly quite well. I'd be tempted to use a framed up fin and tailplane as well, to save a bit of weight.

I think I would definitely try the GWS if I built it tho Maybe an order to Nippon Dave is in order.....

#14 van-S Mar 01, 2003 05:15 PM

I've been spoiled by Mark Rittinger's Rib&Sheet process. I wonder if it would be easier, faster, to glue the ribs down onto the 1/16, then sheet the top 1/16, no spars. For this size wing, it should work fine, maybe be easier to build, and the weight would work out around the same. Any thoughts?

Under 14 oz, and preferably around 11 or 12, this would make a nice plane for the astro 010 direct drive. Please post some photos of your progress.

#15 Ralph A. D'Amelio Mar 02, 2003 09:20 AM

Van-s, thats how I have been doing mine. It quck, accurate strong and you can build washout while adhering the top 1/16 sheet. I haven't seen this issue yet at B&N is it currentlu available in the US or did I miss it?


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