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Mick Reeves Hunter kit build

Started by Turbine Tinkerer, December 06, 2013, 22:47:51 pm

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Thommo

Quote from: Turbine Tinkerer on May 06, 2014, 20:46:56 pm
A short video of the rudder in action. This is 70% travel on the transmitter giving about 35mm of travel each way at the root.


http://youtu.be/ovcYzrajEVA


Looks to be working well, centering seems consistent.  :af

Turbine Tinkerer

Certainly does Paul. I have all the travel I think I need on the rudder with only using 70% of the available 140% of servo travel on the transmitter with it being 1-1 drive. There's nothing I can do about this with not being able to get any mechanical advantage with pushrod positions etc.

Anyway on with the build and back to the wings I think.  I started with the wing dowels in the kit these are just hard wood dowels but I decided to replace these with some turned up alloy ones. I drilled a hole in the back end to loose a bit of weight. Roughed up the surface where they go through the ribs and glued in place with epoxy.

Turbine Tinkerer

Made some ply plates up to mount the aileron servos today and fitted m3 captive nuts to them. I'll make some brackets up from aluminium angle to fix the servos in place. Also added some ply plates with m3 captive nuts to mount the drop tank pylons. Hopefully I'll soon be ready to close of the bottom of the wings.

Turbine Tinkerer

I wasn't entirely happy with how I had mounted the aileron hinge pockets. So I decided to scrap the balsa block idea and replace them with 3mm birch ply. I also put some in the spaces where there are no hinges to add a kind of extra rear spar.

I also knocked up some servo brackets from aluminium angle for the aileron servos and glued the ply plates into position.

Turbine Tinkerer

Well nearly a year since I last touched the hunter I dug it out tonight! Had to have a quick recap to see where I am up to! Anyway it's awfully quite on here anyone interested in me carrying on the build on here?

tsr

Yes please always interested in seeing models like this taking shape.
Any landing you can walk away from is a good one.
You may need a box of tissues though!

THE BLACKBIRD

Yes please im very interested in the build as I am still looking to do the  MR Lightning one day
The man that never made a mistake
Never made anything

Charlie C

Global Moderator

Turbine Tinkerer

A quick update then.

Both the wings now have the bottom skin fitted. The second one done tonight  (I did the other one before I put it away last year) Pretty much the same process as fitting the upper skin, sand all the ribs level, cut the skin roughly to size (I cut out for the gear best I could but may need modifications) and weigh down with bars. In the kit there are a couple of jigs similar to the ones used to build the tailplane. I think these should produce a fairly straight wing. Obviously the wings become very ridged once the second skin is attached. Photos to follow

Turbine Tinkerer

A quick picture of the wing having its bottom skin fitted weighted down with flat bars. Not a lot to see really. I got the edges trimmed ready for the leading edges.

Turbine Tinkerer

Decided to take a diversion from the wings and tackle the drop tanks. The pylons are laser cut 3mm ply. I've put some carbon tubes in for the bolts to pass through that hold them onto the wing. The tanks themselves are from rolled proskin with the nose and tail vac formed in two half's. I spent a while fighting with the proskin to make tubes which turned out quite well. Then onto the nose and tail! About a hour for one tail end. Not a easy task at all! Although with a little filler and fettling I think it will be fine.

Turbine Tinkerer

Managed to get another drop tank tail end glued together today and the proskin onto the pylon sides. Also glued the balsa leading edges onto the wings ready for sanding to shape. The wing tips are vac formings like on the tail but the wings have a balsa rib to fit inside the tip included in the kit. I glued the rib inside the vac forming at the correct place and then trimmed it back to the rib. Hopefully this will work out correctly!

Turbine Tinkerer

The leading edges are shaped to the wing a little more time consuming than most wings with the dog tooth half way down. I've also fitted both wing tips. These haven't worked out as well as the tail tips and will need a little filling. Spent some time fine tuning the fit of the ailerons and added the leading edges which will fair in the hinge gap hopefully.

Waiting for a decent bit of weather to get it assembled outside and see what it's going to weigh before I decide on a power plant. Has anyone got any ideas on this? I have read quite a few of the artf's have had 140's fitted but I would have thought this a little excessive? I was thinking more along the lines of one of the new small size 100's  either from wren or jetsmunt.

Anyone have any experience of the Hunter at this size?

Thommo

Quote from: Turbine Tinkerer on March 04, 2015, 18:45:10 pm

Waiting for a decent bit of weather to get it assembled outside and see what it's going to weigh before I decide on a power plant. Has anyone got any ideas on this? I have read quite a few of the artf's have had 140's fitted but I would have thought this a little excessive? I was thinking more along the lines of one of the new small size 100's  either from wren or jetsmunt.

Anyone have any experience of the Hunter at this size?


Terry, you already know my thoughts on this subject!  :''

As MR says:
"Home built engine, 7 kg thrust.
20 mph wind. KJ66. Model weight 10.2 kg without fuel. Three litres carried.
I did rolls, loops, Immalman, inverted, all fine"


HarryC

My first jet was a swept wing fighter of 9kg with 54N thrust.  Similar thrust weight to 12:7  (10kg dry plus 2 kg fuel).  Performance was soggy, yes it could loop but you had to take long full power run at it and keep the loop small else it flopped over the top.  Take off in light winds took 100 yards + especially in hot summer days.  Changed up to 63N and that was okayish.  Changed up to 80N pushing 9kg and that is fun.  So yes, a 70N engine pushing 12kg of model does work, if working means small loops and flopping over the top.  You will regret it.  100N pushing 12kg will work nicely.  MR says a 70N engine works on the Lightning.  I doubt mine would get airborne on a 70, mine needs a 160 and the few others I know of either fitted a 160 or started lower and ended up with a 160.  I take his figures with pinch of salt.

Turbine Tinkerer

I understand what you're saying Paul but 10kg model + 3 litres of fuel flying on 7kg thrust?  I think it would be pretty much flat out all the time? I agree Harry some figures on websites can be a little optimistic to say the least. I think it would fly on 7 - 8 kilo of thrust but I think definitely would need tarmac. I think a 10 kilo engine would be a good combination with enough power for decent performance without being too overpowered. But would it be able to get away from a decent grass strip? I think a 14 kilo engine would be overpowered but wouldn't have any problem flying from grass and with the difference in weight from the 100 to 140 is there any point putting a 100 in it?

HarryC

Off grass?  Are the main legs trailing link?

Turbine Tinkerer

No there not unfortunately. But the mains are 4" diameter

Thommo

Quote from: Turbine Tinkerer on March 04, 2015, 18:45:10 pm

I have read quite a few of the artf's have had 140's fitted but I would have thought this a little excessive? I was thinking more along the lines of one of the new small size 100's  either from wren or jetsmunt.

I think a 14 kilo engine would be overpowered but wouldn't have any problem flying from grass and with the difference in weight from the 100 to 140 is there any point putting a 100 in it?


Think you've answered your own question...  :af

Turbine Tinkerer

Yeah I think your right Paul,  I'm looking for a small light efficient 120 size turbine but no one seems to make a 120 anymore!

HarryC

Engines have moved on so far in the last 2 or 3 years that for example the Wren 100 is the size and weight of the original 54,  the Wren 180 is the size and weight of the old Jetcat 120.  Whatever brand you go for you might consider getting an engine of the size and weight that the Hunter was designed for all those years ago but which now has vastly more thrust as this gives you many more options for what model it goes into in future, just remember to keep it throttled back in level flight so as not to overspeed the model.

Or go the other way, match the thrust of the original but nowadays that will be a smaller and lighter engine.

Flying off grass you want to keep max ground speed to a minimum which means lowest wing loading to give you lowest lift off and touch down speeds.  That points to the smaller lighter engine, however the modest weight saving and the speed squared parameter in lift may mean that the difference is only one or two mph in which case the same weight but more power might suit you better.  There is no easy answer!

Thommo

March 06, 2015, 09:40:32 am #101 Last Edit: March 06, 2015, 09:41:58 am by Thommo
Depending on the AUW a 100N  turbine will give you almost a 1:1 thrust/weight  ratio, or 30% more than a KJ66...!  :)

Thommo

Quote from: Thommo on March 06, 2015, 09:40:32 am
Depending on the AUW a 100N  turbine will give you almost a 1:1 thrust/weight  ratio, or 30% more than a KJ66...!  :)



Need to brush up on my math...
100N is 42% more than a KJ66..  :embarassed:

Turbine Tinkerer

March 06, 2015, 19:34:48 pm #103 Last Edit: March 07, 2015, 07:20:31 am by Turbine Tinkerer
I don't think anyone would have noticed Paul!

Progress  has been slow this week but there has been progress! Both ailerons have their balsa leading edges fitted and sanded to shape I've also permanently glued the hinges into them. I'm quite happy with how it's all worked out  a nice fit on the ailerons and faired in hinge lines with about 30mm of movement up and down which I think will be plenty.

I'm hoping to get outside tomorrow and assemble it to get a idea of what it's going to weigh and to remind myself of what I'm building!

Turbine Tinkerer

Put it together this morning and weighed it. I had all retracts and legs in thrust tube in place and the rudder and elevator servos in. I needed 1kg of ballast in the nose to get it to ballance somewhere near the c of g.

Airframe, retracts, legs, servos, thrust tube 6.5kg
Ballast                                                                 1.0kg
Remainder of servos                                          300g
140n  engine installed                                       1.5kg  or
100n  engine installed                                       1.1kg
Finishing  paint etc????                                     2.0kg

11.5kg + fuel?? With a 140 or around 11kg with a 100

Looks promising either way unless I'm grossly underestimating how much weight I'm going to add in finishing it?

Thommo


Looks good Terry  :af

Think you have have over estimated the weight of finishing as you won't need to glass cloth the flying surfaces, so only needs a couple of coats of paint?

Shame about the 1kg nose weight too.

STORM

March 07, 2015, 16:16:49 pm #106 Last Edit: March 07, 2015, 16:19:05 pm by STORM
On the contrary, you have underestimated, it's quite suprising how much extra it will weigh afer you have filled it up with all the necessary junk!
The Cg will improve as well.

Turbine Tinkerer

March 09, 2015, 19:43:19 pm #107 Last Edit: March 09, 2015, 19:45:10 pm by Turbine Tinkerer
Do you think Gary? I was thinking that the batteries will take place of some of the ballast. The cockpit will add a little weight but that will be in front of the c of g  so again reduce the amount of ballast. I'm not planning on a powerbox and just a couple of electronic air valves for retracts/gear doors. Obviously there's paint to add too.

Back to the build and the flaps are now hinged and I've done the remaining of the lower wing wing skin around the flap area.

The piece of skin missing in between the flap and aileron is missing on purpose to aid aileron removal as Phil suggested

STORM

March 09, 2015, 21:29:54 pm #108 Last Edit: March 09, 2015, 21:32:29 pm by STORM
Yes Terry, I did a weight exercise with my new L39, it's quite amazing how the little bits add up, cables, tubing, screws, uat, spar, ecu, switches etc. Looking good. I reckon a 100 will shove it around nicely though.

Pete96

very precise kit building. Amazing stuff.

THE BLACKBIRD

I have built a scratch built hunter the same size as the MR one and it weighs 23 lb with a  temp set of retracts on it and no paint, wings done in Pro- Skin, 3lt tank , all electric and a JC 100rx and it fly's very nicely, but I find paying £ 700 for a set of retracts for a model that cost £250 to build to much, so its never been finish  :'(

Tony
The man that never made a mistake
Never made anything

Turbine Tinkerer

After a long lay of I've started on the Hunter again  (I will get it finished!!)

Both aileron and flap servos are installed now with the servo covers made. I've made wing root ribs from proskin and attached them to wings and started to add the fillets as the wings are smaller than the fuselage moulding. Photos to follow.

Pup Cam

Quote from: Turbine Tinkerer on October 02, 2015, 17:29:47 pm
After a long lay of I've started on the Hunter again  (I will get it finished!!)


I find that's how model building goes ....  :''

Keep up the good work, the Hunter is one of my favourite (there are so many!) aeroplanes.

Alan
Still distracted by a 1953 AJS 16MS and now a 1939 BSA 250 too!

Turbine Tinkerer

Got the main gear doors cut from the fuselage and looking into hinging these with standard gear door hinges and actuating them with micro servos rather than the traditional air rams. Has anyone any thoughts on this?

paulinfrance

Servos are mainly used over here with radio door sequencers,,

https://www.youtube.com/watch?v=7hbU4Wi2-Go
Mode 2 THE only way to fly

Turbine Tinkerer

I've managed to get the main inner gear doors hinged with 3 standard door hinges. Maybe a little over the top but the central hinge lines up nicely with a internal fuselage former where the actuating servo will be mounted.

The nose doors have been a little more complicated! The rearward door is opened by the nose leg which is fairly simple until you add the complication that the nose leg rotates to steer the model on the ground. I've come up with a piece of piano wire that slides in and out of some brass tube connected by ball joints to the nose leg and then the nose door is pulled towards the nose leg with a spring. Hopefully the photos will explain it all.

Turbine Tinkerer

A sort video of the nose door mechanism in action here -



If you have any better ideas please share!

paulinfrance

Mode 2 THE only way to fly

Turbine Tinkerer

One of the stumbling blocks I have come up against on the Hunter is the nose leg steering. After a lot of thinking I've come up with a mechanism where the steering cables go through nearly 90° in a aluminium tube and up to the servo. It looks to work well but needs a little fine tuning.

paulinfrance

October 23, 2015, 08:06:46 am #119 Last Edit: October 23, 2015, 08:18:35 am by paulinfrance
Looks interesting, maybe a couple of plastic pulleys, or 2 micro servos either side pulling one wire each ?,,

Another solution is a couple of these 90° hinges, fix the right side to the bulkhead (one each side) cut 1/2 of the left bottom piece off  and fix the control wire to the top piece left,,
Ok a bit Heath Robinson,,,  :''
Mode 2 THE only way to fly