I just got one today.  I have  been pondering  on which  one to buy  for weeks.

I made the decision to go for the H9 based on price, quality, and size. Also the fact that the LHS had a few in stock, made it easier to choose.

Well I intend to build (assemble!)  this over the next few months.  Model will be electric powered with Horizon Retracts.

 Initial inspection of the box of bit showed a selection of well packed parts. The covering appears very smooth and wrinkle free- and shiny. So that will be sprayed with a matt finish laquer. Anybody have any advice on suitable products?

I don't intend to do museum-level scale detail but I will give it a few essentials.

The first thing to deal with is the retract fitting. These are sturdy units, but about 4mm too wide, so I have to decide wether to alter the model or trim the retract..  Sleep on that one for the moment.

I have obtained an electronic retract valve from Inwood Models. This operates directly from the RX without a servo. Not cheap but , so I am told, has an industrial grade miniature solenoid valve. Inwood has these made specially. Hopefully this will be more reliable than the traditional method.

. I am a great believer in the 'better mouse trap' philosophy!  

So if anyone is building, thinking about it ,or wants to contribute to this discussion, please feel free to put your 4 pennyworth in 

.  

Which valve did you go for?

I wish inwoods would show a picture and a description of what your getting.

Anyone else do electronic retract valves?

Hi Shaun 

Dave (Inwood Owner) is a lovely man, but sometimes gets carried away with ideas.

It is not easy to market everything as well as possible. He doesn't have time to tell everything to everyone.

Basically he has had this very small circuit board made to operate a miniature air solenoid valve. As I am an electronic engineer by profession, I was pleaed to see the quality of it. This is a robot-produced circuit board, which is flow-soldered using the latest circuit production techniques. This is where many identical boards are made together, a bit like the way they make microprocessors on a silicon wafer (only bigger)

The individual circuits are then removed. A servo plug lead is soldered  on the board and two more leads connect to the air valve solenoid , and the whole thing is wrapped in heatshrink plastic. It is possible to use the same system with single (spring down) or double  air valve  unit. 

Dave gave me it in bits  to  finish off  myself. I will  take  a photo  tomorrow  and put it in my photo gallery .  The reliability should be assured , due to the fact that the valve is of industrial quality, and very unlikely to leak. As I am using air up & down retracts, the last thing I want is a wheels up landing on a B25.

So, the short answer, is its not a branded product. Maybe a Google search  will find something. If not Dave's got a world class accessory. Price is @ £45.00

I shall be assembling the parts and testing the unit  this Saturday, so stay tuned and many thanks for your interest 

I noticed YT international does a similar type of solenoid valve RRP £40

Don't know if it is ok or not ?

Retract Valve- Update

I assembled the retract valve today. Just a case of 5 connections to the postage stamp sized board. Its then stuck to the solenoid valve with a double sided sticky  pad.  Not shown in the photo, its now encase in shrink wrap (heat shrink). 

I plugged it into the reciever, and you can hear a tiny 'click' when it operates. Thats it then, till the retract plumbing gets done.  You will usually buy these ready made from Inwood Models.

 The unit is about 2" long. You can clearly see the air line connectors. The solenoid is under the circuit board. The valve is made by a company called SMC.

Details are here: http://www.smcetech.com/CC_host/pages/custom/templates/smc_v2/prodtree_branch_group_2.cfm?cc_nvl=((CC,SMC,V_M_US,Node_27250))

 I decided to tackle the retract for the main wing nacelle . The nacelle is designed like a small monocque fuselage which then attaches to the wing with dowells and nylon bolts. The nacelle then hides the flap servo  and horns. 

As I am using Horizon retracts, a bit of surgery  is required. I also want functional retract doors. The wheel lies on the centre line of the nacelle, which means the retract frame is off centre.

The retract frame  sits on rails between two bulkheads . I was able the remove the rear bulkhead fron the nacelle intact. Bit worrying really, to get it out that easily!.

I

 .

With a dremel  (I bought my old man one for Christmas.) I cut out the glass fibre part for the doors as there is a bulge where the wheel lies when retracted. Hopefully I can use them for working doors.

I use Polyeurethane clue from Titebond. It  can be a bit messy, but sticks as strong as epoxy , fills gaps, and remains slightly flexible. 

It took about 4 hours to accomplish one nacelle, allowing for the trial and error, I should take about a quarter or that to do the other one!!

Here you can see what a snug fit the nacelle is on the wing

Here's a photo of a bomb bay full of lipo's

They are attached to a removeable tray . This is attached by tongues in the front bulkhead, At the rear. the tray is secured by the wing bolts. The bottom cover is then repaced with pegs an spring catches.

Qiute a neat arrangement for getting the lipos out at the field.  Those batteries are 5000ma / 3S / 20C .I bought them direct from the PR of C for about £25.00 each.

So thats 22-24 Volts per motor.  . That should keep it up for a decent flight time.

Eagleman

I just had a look at YT re the retract valve. I would say its the same one.

Not sure then who gets it from who .  Still, thats another source for the unit.

Thanks for your interest 

I used to be a display model maker, in another life . I had all the gear, spray booth. fans, guns, paint etc. Boy, did I have some pretty planes back then..

I want someone to suggest where to get a decent matt polyeurethane spray can . If it can go over the shiny 'sillyfilm'

Someone said you can 'key up' the film with an old plastic scourer pad??

Maybe next winter I'll strip it and do a glass cloth job, I dont really have the space to do at present.

Hi Peter

Enjoying your blog,

Just goes to show  how ARTF's need quite a bit of work/re-working to end up with a good model.

Cheers

Kelvin

Try saying 'Freak Stree Frinish' after a Sat night down the loca l  The words 'paint grade'   presumably means not so agressive .  Thats great advice, though I only need  a matt finish over what's there already .

Had a chat with Mr Unitracts today. He is going make me a set of custom oleos for the Horizon retracts. They have a damping system using high viscosity grease which seems like a good idea. I have one nacelle now completed, except for the doors. As Kelvin says, its not an out-the-box, but now I will be having what I think is a very sturdy retract system.

 I did a bit of work on the nose leg. The full size has the leg raked forward. Robart has a unit that does 120 deg, but mine don't. However, the nose wheel is smaller than the mains, and due to the depth of the mounting, I can pack the retract up get the forward angle , and still get the wheel in the well.

I've been giving it some deep thought over the motors & ESC's. I think I'l be using Castle C's Phoenix 60A units as I have one brand new one already. I also have the USB programmer lead. 

I need about 900 Watts on each motor  at  about 22V  Thats about 40A . An 8 minute flight will need up to a 5000ma from a 6S pack. I have four 3S 5000ma packs that I paid £100.00 (from Sun High Battery in China)  They're the ones in the photo. I am going to need two 6S chargers with a split balance plug on each to recharge the 4 batteries. I will probably get the Imax BC8 as I have some 5S packs in my Spitfire to charge as well.

I have a good Idea what motors I will get. Anybody like to make some suggestions?

PS type 'Hangar 9  B25'  into Google (Fame at last! )

So-ooo lets turn the solution upside down, and stick the bolt in from underneath.

I cut a piece of dowel to length, and drilled a hole through it. I then enlarged the end to recieve the head of the bolt. Finally glued a steel washer on top. This is to provide a 'surface for the bolt to tighten against'.

The dowel with captive bolt is then glued in place with a few dabs of cyano. This bit is not especially mission critical as its only providing a guide for the hex key, 

 I also glued a ply plate to the bare (and very hard )balsa on the underside

The T nut is now inserted in rrom the top of the tail surface and through into the reinforcing ply plate underneath.. The bolt is screwed up with a long hex key through a small hole in the fuselage bottom and the tail pulls down tight . 

The rear canopy is glued to the tail with canopy glue, and when dry, the whole tail can be removed complete with the canopy. I can still glue the rear gunner in place throug the open end of the canopy when the tail is removed.

I cant show a pic yet as there sandbags holding the canopy  till the glue sets!

There now. how hard was that? 

Looking good peter i have got the hanger 9 sothworth cammel yet to build its intresting on the comments to dull it down also have you got a link to Sun High Battery ( hope thats ok Dave ) if not could PM me with it.

Martyn  

Hi Martyn

Your best bet is to look in the UK RC Model magazines for Hobby City in Hong Kong as they offer  similar prices for smaller quantities. They are CE approved.

Thanks for your interest 

Here is a photo of the tail group all glued up

I have done more work on the Undercarriage. Good Old Dave at Inwood Models got me a complete set of oleo legs for a miserly £26.00.   They are designed by Advanced Scale Models. made in China (of course) Thats a 'no brainer' of a price!  They are designed for another model but an hour or two 'fettling' had them fitted. The nose leg on the B25 is raked forward (120 deg retraction). However, as it is quite deep set, I simply cut some tapered wooden shims. This achieved the desired 'look', and it still retracts fully into the well.

The main undercarriage is now fitted into the nacelle. These are 'handed' to allow the axle mount to clear the wheel hub

This is looking very good Peter. What motor /prop combo are you using, and have you run any static rtests of the powertrain yet?

I saw your quote " So thats 22-24 Volts per motor. . That should keep it up for a decent flight time".

I take it from this then that you are running 2 packs in series feeding each motor, which will actually be about 21V under load, and this depends to large extent on the quality of the Lipos -but you dont say what the current draw is, and therefore I wonder how you have calculated the flight time.

As you know, the voltage level will not be factor in determining duration...capacity of the packs will.

Perhaps you are running 2 x brushed motors in series with all packs series wired ?? Just interested....

I have a hangar 9 Sopwith camel awaiting construction in the workshop

oops...just noticed you have mentioned motors elsewhere in the thread -sorry !

Heres a few suggestions....

Hacker a5016s

eflite 60

AXI 4130/16 400kv

if you are on a budget, how about the turnigy- I have one for my camel, and am impressed for the money - £22 !!

TURNIGY 50-55A 400kv Outrunner

16 X 8 or 10 prop ( or nice scale looking 3 bladers ? )