essyou35

My Feedback: (11)

Just FYI, it comes out way tail heavy. I would put the UAT in the nose area.

Quandry

Thanks for the comments guys, I took another read through the whole thread and saw that other folks also were noting the CG to be quite rearward. After laying out all of the electronics and equipment that needed to be installed inside the fuze, I realised that a lot of important stuff would turn out being smack in the middle of the air path. While I'm less worried about the turbulent air, it is a concern that anything that might be injested in the forward duct while flying (a bee, small bird, hail stones etc... [joking]) is likely then to be fired straight in to the RX or maybe worse the Gyro.

So I decided to do the 'nose cut' mod as demonstrated way back in post #639 by profgigawatt. So tonight I'm bringing you back! to the future....



I used the thinest Dremel cutoff disk I could find. It was quite effective at getting through the skin of the dog. The hardest part was holding the plane steady while cutting, if you're going to attempt this I recommend having a helper.



After opening out the nose area I cut up an old Pizza box as a template to design a fitted tray. What really surprised me is how much room was hiding in the nose, you can fit a lot in there!



I cut out the new tray from 3mm poplar/carbon sandwhich. Very strong + very light and also leaves a nice finish. I have an el cheapo scroll saw that doesn't like cutting the carbon much but it gets there in the end. I also made a sizeable cutout that will be useful for getting in at the front nose wheel mounts. The way I land, I need this kind of maintenance hatch! My cunning plan is to make a screw on piece that will be attached to the glued in plate, this will house all of the electronics so they can be put in our out for maintenance purposes.



After gluing in my tray I then made up the nose former, with a matching one for the hatch cover. The tape sits in place for now while all relevant glues are applied and then I remove it later to leave a tasty looking 'fresh carbon' finish. Next steps is to make up the rear formers and finish deciding if this will be a hinged cover or velcro.

Quandry

Postman just delivered to me two Xicoy Spektrum telemetry adaptors! One is for my Dog (Kingtech 100) then other is for my buddies ViperJet. Yes having turbine telemetry on the TX is more of a gadget than an essential but I really enjoyed having it on my p20 so I'm hoping the Xicoy experience will be just as good.




btw Essyou35, would you mind making your signature a little smaller? you contributed a lot to this thread which is great, but when I go back and re-read it a lot of the thread is your new (and long) signature...

Quandry

No huge update from me in the past couple of days. I made some more carboard templates and weather willing will be cutting out more formers on the scroll saw this weekend. I might run a couple of small but strong internal stringers to join up the nose woodwork with the wing area framework - just for piece of mind

As an aside though, for anyone interested in Sabre's there's a great online resource to be found here: http://www.sabre-pilots.org/ . Their magazine 'Sabre Jet Classics' makes for very interesting reading, all of the stories, articles and photos really bring such a rich history to light.

Are there Sabre-Pilots members on here?

Quandry

Well the dog build has been progressing a good bit over the last few days. I ran in a set of tbolt servo connectors (fueslage end) and designed up a click together gyro mount for the Cortex. The standard Dog Sabre kit has a former mounted bracket for the pull/pull steering servo. I changed my steering way back to an eflite linkage type, so I decided to reuse the former slots for a gyro mount. This locates the gyro reasonably close to the CG, in the center of the plane so hopefully should work well.



Scroll saw + Dremel =




After gluing this in with Hysol I can now pick up the whole plane by it so I think it should work


Still toying with the location of the CAT

Quandry

I then moved back up to the nose cut out. My plan is to use a hinge system on one side, and a release latch and clasp on the other.

Soft tronic hinges were duly scored




First job turned out quite neat, however there was not enough contact area and the hinges pulled away from the Hysol after it was dried.


I've now drilled holes in them and restuck them and covered both sides so they have to be stuck.

I picked up this handy Pichler aluminium latch release at Jetpower last year. Shame I didn't buy more as they seem to be hard to find?

Quandry

And while that all dried I took a look at some more of the electronics install. There's a lot of stuff to go in here.... especially considering I need to leave room for the air to move through from the nose to the turbine. There's something to be said about side duct design!



At the moment I am thinking of a vertical side 'Spektrum plate', the regs will go on a plate next to the nose retract with the fuel pump on the opposite side. The Xicoy ECU, telemetry adaptor and GPS will go on to the nose plate behind the batteries.



Everything will be velcro attached, but also with velcro safety straps over the top (dotted lines denote)



And that's it for now, but I hope to grab a couple of hours to do more later tonight..

sidgates

My Feedback: (2)

Quandry - Thanks for the update. You insprire me to get back on mine.

Quandry

Thanks Sid! you're work on the air brakes inspired me to try the nose hatch mod, and now that I've done that I'm going to take a stab at the air brakes because I liked yours so much .



So I got a little bit of time last night to crack on with a few things so I bit the bullet and made up my Spektrum RX tray. I don't want to hard commit to much in terms of placement until I've had a chance to run a CG mockup, but I figured that having a vertical tray is only going to help matters because I have so much stuff to mount anyways. Thinking about it I will probably make an identical one for the other side to keep things even.

cheers,
Geoff.


For the side plate I've gone with carbon/poplar stringers and carbon look ABS plate. The actual plate itself will not take a lot of stress so there's no point using the carbon/poplar which although it is very strong and light it's also quite expensive.



The mounts are just light ply blocks CA'd together. I marked out the areas on the stringers, ground them down a bit and CA'd the ply blocks on. It joins quick and holds fast.





The tape on the plate and stringers is used for marking purposes, also as a covering strip while applying glue. If you get any overshot then it's easy to peel off and leaves you with a nice neat line.



It would be nice to tounge in groove this install but honestly that is beyond my 'beginner grade' skill set. This is also not a load bearing framework but just something to hold up an accessory tray so I elected to do a rough measure, tin the edges with Hysol, hold in place, tack with CA to keep it where I want it and then seam fill with hysol.

Quandry

So just a few updates with the Dog Sabre. I figured it was no use makeing a Receiver plate without having power operational so I came up with another plate design that would fit dual regs for my AR12120. This is again a vertical plate that secures in the nose next to the retract to try and counter the tail heavy weight balance that folks are reporting. So two Spektrum 6v 10Amp regs:



To secure this I glued in stringers and velcrod on to that, and then for good measure added a safety screw. I would have done more than one screw but despite how roomy it is in this picture it's extremely hard to get at anything in there. The Velcro is also Align type which is pretty much the most heavy duty/sticky velcro I have ever found.



With the regs in play it gave me the idea to make a V2 RX tray that does not leave gaps so I can hide my wiring (or at least try). You can see the V2 tray in this picture. I also made a trial hookup with my X Plus adapter. In the time I've owned my DX18QQ I have never needed to go beyond 12 channels, however with this model I'm taking it to the limit and already using 13 with a couple more planned for the future.



With that in play I decided to temporarily wire up the RX to set throw limits, checkover linkages and retracts etc. This left me with a bit of a cable nightmare, but also the Dog sitting on her three legs for the first time - exciting!






And so the next step was to run through the initial setup of the Cortex and start on tidying up the wiring. I'm part way through at this stage, once I get that locked down it's time to do the fuel plumbing and fit the header tank, install the turbine and fire this sucker up!

Quandry

Well folks just a quick update on this thread. I've been tipping away at the final parts of the build. Not a whole lot to take photos of so here is a short text summary:
* Reworked my front retract to make the steering smoother and also extended the leg by 15mm. This brings it back to the same length as the stock leg.
* Installed the nose tray and wired in the ECU, GPS, Turbine Telemetry, and brake controller.
* Tidied up some cable routing in preperation for the final hot glue 'great stickdown'.
* Ran the fuel hose and turbine connections.

With the turbine ready to screw in to place now and test run, there was one final piece of customisation to tackle - the turbine hatch... The kit has a precut hatch that is lined on two sides with very light ply - popsicle stick style. To cover this there is a flimsy bit of clear plastic that is painted silver on one side. The instructions effectively say 'figure it out yourself'



I toyed with the idea of just putting the plastic across the wood and screwing it down, however the problem is that it does not fit the profile of the body (close but no cigar) and also I am 100% certain that air pressure would push up against the flap get in to the body and tear it out of there. It may not happen on the first flight but it would certainly happen somewhere down the line. So what I want to do is make the hatch cover a solid fitment and also get it to at least resemble the shape of the body which I will also note is not perfectly symetrical on both sides...

To tackle this I've made up a light frame that matches the outline of the hatch cut out. It was just a little time consuming to take on the carpentry but once I had my scroll saw cutting I managed to get it very close to the profile of the underbody:


Next step is to glue it all together in the plane and I will then make up some mounting tabs which should give a positive and secure fitment. I was considering using hidden pins or hinges, however there's not a lot of room at the front of the hatch because there's a bulkhead there, and ideally I would only want something in that location hinged from the front incase the latch came loose.

Quandry

Well you would think that by now I would be finished on this build and be flying right?

Wrong - still clowning around a bit..

I got the hatch frame finished up, sat it in to place and then glued down the cover (first with 2 pack to locate the cover on the frame, and then hysol filleted for strength):


When all is said and done it is not the prettiest but at least it works


With that out of the way I could finally bolt down the K100


Similar size and weight as a K80, but 2kg more thrust..


After that it was a case of runnign the ECU wires and setting up my Xicoy Telemetry, it works nicely which is great because I really liked using my Jetcat sensor with my P20 Habu

Quandry

With the electrical setup out of the way it was time to plumb the tanks and lines. I fitted an Intairco breather to the bottom of the Dog. Just by co-incidence it seems to be colour coded:






Then it was time for a runup in the back garden (sorry neighbours!!) - this was a necessary test though and I found out that I had a problem on my last fuel tank breather.


I also pulled together my battery payload - 1 x ECU pack (4,200mah), 2 x RX packs (2,200mah), 1 x wheel brake pack (450mah). Should be good for a lot of flights with that amount of power onboard and pretty much eliminates any need to add lead.



For interest, this is how they are laid out in the nose. I took the opportunity to cut out strap slots in the tray while I was there also (but not shown in this pic):



But I'm still waiting on a few final bits. Some large Tygon that will fit my CAT fittings, and some brass reducers. I'm also putting a magnetic latch on the front of the nose hatch to compliment the pin at the back. The weather is not great here at the moment so it gives me some breathing space to get these final pieces in place and ready for maiden flight.

Any one else had any Dog activity recently?? (flying or building)

red76ta

Looking good! I still added 4 ounces of lead to the nose with a similar battery set-up...air brakes in mine! Happy flying!

sidgates

My Feedback: (2)

Quandry
I am interested to see your use of the Zippy packs. I have been using a Zippy 700mah LIFE for servos and receiver in a foam P-47 for nealy a year and based on this experience have recently changed my Boomerang Intro to Zippy 1500mah (2 in parallel) for the servos and 2 of the 700mah in parallel for the receiver only. The turbine battery is a 2100mah Lipo.

Red76ta,
If you have pictures of your air brake I would be interested in seeing it.

red76ta

Sid, I was referring to the wheel/brake set-up. I have the spring air retracts with brakes and am using a single air tank for both the retracts and brakes. Sorry it sounded like in installed airbrakes...


Bill

sidgates

My Feedback: (2)

I thought somelse had done speed brakes and if so was curious how they worked out.

Quandry

Thanks Bill and Sid

On the Zippy pack, this is the first one I ever bought. I normally use Giant Power / Dynergy LiPo's which I found to be very reliable and excellent discharge rates for EDF usage. Giant power didn't have a readilly available 3s LiFe pack though (needed for the Kingtech 100) so I landed up ordering a Zippy and will see how it goes. Good to hear you have had some success with them though Sid.

Quandry

Folks, just wondering is anyone here running their Dog with a 100 size turbine and will the standard pipe work OK with it?

Any pipe comments or failures to note from anyones experience with the pipe supplied with the Modelbau Dog Sabre kit?

I am about 8 days from maiden and would like to try and anticipate any issues.

red76ta

Quandry, I am flying mine with a Kingtech K100 kero start and have not had any issues to date with the supplied pipe. That said, I only have about 15 or so flights on her, but I do not see any hot spots in the pipe so far.

Happy flying, Bill

Quandry

That's great to hear - thanks Bill!

Now I just need the weather to play ball...

Cheers,

Geoff.

Quandry

Hey folks, how are the Sabres flying??

Just to update you I finally got my maiden done two weeks ago - wahoo! The first day I tried I had retract issues and landed up going home with a broken nose wheel. So I landed up switching out my Eflite 60-120's for a set of Electron ER40's. Unfortunately the Eflites were just not up to the job with this bird on a grass runway. I think they would work ok on Tarmac but on grass you have to go with a beefier setup. The second attempt came and the Dog was away like a rocket! She is extremely pleasant to fly and just locked in taking turns and fly bys etc. Unfortunately I don't have any video to show as yet, but my dad did capture three flights and is working on some editing, it's also in the middle of his European vacation footage so may take a while until he can get it put together and uploaded. In the meantime I will make sure I have a camera with me on the next outing to share with you guys how she looks in the air as it's just fantastic! It's the kind of model that you have to be careful with flying as when you watch it fly by, you get distracted and think it's the real deal and forget to work the controls. You have to jolt yourself awake again to make sure you take the next turn

I am so far impressed with the Electron ER40's they are a rock solid setup and worked with my Jet 1a legs OK - I also moved from 60 to 70mm wheels all round. I will try and get a few photos of my setup this weekend when I'm making some maintenance updates on the Dog - including some rework on my fuel tanks that were not draining correctly due to clunk placement etc. No biggy, just little fixes to be made here and there.

The Kingtech 100 goes great in the Dog and makes the Vertical climb extremely impressive. I mostly flew around at half throttle or below and landing at idle on a still day was a non event. Really great plane and I'm a bit dissapointed that Modellbau USA quit when they did as if they would have continued and brought out other cool models at the budget end of the scale I would definately go for it. Yes there's a little bit of building and assembly work required but when you see that bird in the air flying so nicely you get a really great feeling!

Thanks to everyone who contributed their valuable learning to this thread, and also to my wingman Jason and flying buddies for all of the help in getting this far. I am hoping to get many more happy flights in on the Dog this year - just praying for fair weather weekends!!

sidgates

My Feedback: (2)

Geoff,
Congraulations on the successful maiden flight. I am looking forward to the video.

I have been tied up trouble shooting a problem with my Top Gun F-15 with a RAM 500 engine. It has flamed out nearly every time I go to full throttle over the past 2 months. Also the data terminal screen would go to garbage read out when trying to start the engine. My son loaned me his data terminal but started having the same problem. During some bench tests I inadvertantly used a different ECU lipo battery and the data terminal problem cleared up.

Yesterday I removed the home made FOD screen from the engine and had three successful runs to full throttle so I think that problem is solved.

A couple of days ago I was looking at the tali pipe that came with my F-86D and noticed the very small air gap between the inner and outer pipe at the tail. My gap is about 1/8" and wondered if this has been a problem for anybody else. I will go ahead and install it and check fuselage skin temeratures unless someone else has all ready had temp. problems.

Quandry

Cheers Sid!

BTW, I don't seem to have any fueslage temp issues as such and am running the stock setup.

So this weekend a buddy and I headed out to the flying club to get some footage. I got in three flights but dumb thumbed the last one and tore out a retract mount. The glue is drying now so should be good to go for next weekend with no issue. Note that she comes in a little hot, because I had to fit very heavy duty retracts etc to cope with the grass runway we have here. Aside of that the Dog is a really enjoyable bird to fly. Looks superb in the air at any height!

I recommend to watch this in 720p HD

http://www.youtube.com/watch?v=3tN_xqOXfnE

sidgates

My Feedback: (2)

Geoff,
I am glad to hear you can fix it easily. Thanks for the video. It looks fast in the video but maybe it is just being on camera because the landing looked a little fast but the roll out was very short. Good brakes?

Sid