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Old Nov 15, 2012, 01:44 AM
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BAC 167 Strikemaster Scratch Build

Hi Everyone, This is my first Jet Build which I am undertaking for a friend.

Subject is the BAC 167 Strikemaster with the following dimensions etc -

Jetcat P80SE

Wingspan - 2.2m
Fuselage - 2m
Airfoil - Clark Y
Incidence - 1'
Dihederal - 5'

Construction will be traditional built up balsa, hoping to keep the airframe under 3kg

As its my first Jet build I need lots of help so please chip in

Completed the basic wireframe drawing which to some extent is the hardest part, next stage is to work out the position of all components and source things like the exhaust, fuel tank, retracts etc.

Any help/opinions would be appreciated

Ken
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Old Nov 23, 2012, 07:11 AM
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Hi,

Got the basis of the wing construction design completed.

Wing tubes are carbon fibre, frames are a mixture of 1/8th and 3/16th liteply. Outer wing tanks will be glassfibre.

A good portion of the wing will be built into the fuselage to house the undercarriage

Any advice on the size of fuel tank?

Let me know if I am not posting in the right place
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Old Nov 23, 2012, 09:41 AM
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I am looking at a Dubro 50oz / 1500cc tank, do you think this is big enough?

Working out the CG and placing the tank on it gives me a good indication where the P80 can go giving some room for airflow, CG is 186mm back from the LE

Not sure if I worked out the wing loading seems far too low I guess I may have the max Cl wrong
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Old Nov 25, 2012, 02:42 AM
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I think you will be short on fuel.

The sports model I fly is about the same size (AUW 9kg + fuel) with a similar thrust engine (Wren SS) & I have the 50oz tank in series with a 20oz tank plus the header tank which you should never include in your available fuel.

My flight timer is set for 7:40, comfortable for a start, taxi, reasonable length flight & a taxi back. I guess a taxi tank would give another couple of minutes of flight time. - John.
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Old Nov 26, 2012, 01:31 AM
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Thanks John thats a great help, there is plenty of room so I can move up to the 80oz/2.4Ltr tank no problem.
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Old Nov 29, 2012, 09:15 PM
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Here's one I am trying to do for 90mm EDF. It's Jet Provost T3. Love the T5/Strikemaster.
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Old Nov 29, 2012, 09:26 PM
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Was just looking at your wing tube placement. Depending on the area between the tire and rear of the main spar, could you use a carbon fiber or aluminum blade for the wing joiner instead of the tube? You can even do a split spar where you could have a blade in front of the wood spar and one behind it to form a sandwich that will just slide around the wood spar in a C channel. Just a thought...

Will
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Old Nov 30, 2012, 01:41 AM
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Hi Will that looks phenomenal, keep us posted on the build

Interesting concept for the wing joiner, I have spent the last week changing the design of the wing to stressed skin construction so will work out if the idea works better

Thanks, Ken
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Old Nov 30, 2012, 05:07 PM
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Here is a T5 version I drew in Sketchup. Can't get the nose section just right...
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Old Dec 06, 2012, 04:02 PM
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Been reworking the model some. Intakes enlarged 9% from scale to get 100% FSA of a 90mm fan (7.6 square inches). Wingspan is 60". Length is 51".
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Old Dec 14, 2012, 01:49 AM
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Looks great Will, I will soon need to be thinking about intakes

I dont think I have ever spent so long designing a wing! I made two decisions, first to change to stressed skin construction so I needed to enlarge the wing ribs by 1mm and take away the cut notches for the stringers, then thought that Will's suggestion of a flat spar joiner was a good one and re-designed the whole wing to suit.

I think it has worked out well, will be stronger and lighter, using 2mm carbon for the spar and pockets into which it slides

I still havent finished yet as I need to think about how flaps and ailerons will work
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Old Dec 14, 2012, 10:41 PM
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Ken,

Just go a new router after my last one went out on me. Progress looks fantastic! I hope your new spar works out. It looks like a much cleaner install than a what the tube would have been. Think it's lighter?

Will
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Old Dec 28, 2012, 03:15 AM
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Hi Ken

Just found your thread while researching for info on the Strikemaster, I am planning to be building a scratch built 1/4 scale. The biggest problem I saw was the wing attachment as previously built models with two main wing panels plugging into the fuzz can suffer from wing failure, like you I propose to do a 3 piece wing with the center section carrying the retracts and the tips plugging in similar to your design. I would like to possibly incorporate the center section into the fuzz like you intend but width may be a problem at around 42", for storage & transport. I will follow your build with interest.
Dave
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Old Dec 31, 2012, 05:45 AM
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Ken I think you graphics of you design are great, I am still in the age of drawing out on lining paper. What drafting package are you using.
This is the info on the Strikemaster I have to date.
Full size
Span 36' 10" over Tanks
Length 33' 81/4"
Dihedral 6 degrees
Incidence at root 3 degrees
Incidence at tip 0 degrees
Root width 7' 8"
Tip width 4' 4"
Wheel track 10' 8.9"
Wheel base 9' 7.4"
Main wheel 24" dia
Nose wheel 16" dia
Aifoil section NACA 2315 (modified) at root NACA 4412 (modified) at tip
Tail span 13' 6" ( I do not have the tail incidence as yet )

From this at 1/4 scale I will have a span of 2807 mm with a root chord of 584.5 mm and tip chord of 330.5 mm. Depth of rood rib 85 mm, depth of tip rib 45 mm. 100 mm nose wheel & 150 mm mains which will be great for grass.
Length will be 2567 mm with a tail of 1030 mm. Power to be Wren Pro 160 with estimated weight dry 42 lb (19 kg). Retracts will be Premier UK units 85 degree reverse acting mains and a 90 degree nose unit with custom legs supplied by Kingfisher Aviation.
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Old Dec 31, 2012, 09:02 AM
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Just found some more info contradicting my previous posting regarding wheel sizes.
Mains are 21" dia x 6.75"
Nose are 16" dia x 4"

so my mains will be down to 5.25"dia which are still ok for grass.
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