marc s

OK back on the project following some time on pressing 'other' jobs.

Now the retracts from Electron have arrived and the legs from Jet-1A, who I have to say are very helpful indeed and offer a great service.

Having heard from a few the nose gear and mains mounting plates are a little weak I added and beefed up the nose gear mounting with some extra ply formers glues to the existing and Aeropxied in place, I also added some extra ply to the rails to add some thickness to them to help achieve a stronger frame.

The Electron nose retract has the built in steering coupling, its a nicely made unit but I was struggling to work out how to hook up a servo to it without having to use wire connections which I personally hate. The Gryphon has a servo plate already fitted just forward of the tank but I decided to try a more direct linked system. I cut a piece of FR4 to fit round the main retract body and use the mounting holes as a fixing point, the FR4 plate then extended away from the main unit to allow for a servo to be mounted on it a few inches away from the steering tiller. I connected the servo to the tiller with clevis links and made sure the hole positions for the servo arm matches those of the tiller arm to avoid issues. The unit seems strong and fits nicely inside the nose section, gives positive steering, no slop and no wires to get hung up.

The wing wheel well cut-outs were not centralised on one wing, I suspect the template used to cut these moved during the routing process. Looking at the tyre options from Jet-1A I wanted to use as large a wheel as was possible, three reasons, one its better for grass to have a bigger wheel, second the ones I have seen fitted to some Gryphon's just seem a little too small, and third as I want to try to fit our new e-brakes I needed to give myself as much room as possible in the wheel hub area. I chose 75mm diameter wheels and 147mm long legs which seemed about right.

I had a friend cut me a couple of ply jigs to re-cut the wheel cut-outs, these included an 85mm diameter wheel hole to allow for the new bigger 75mm unit. A Proxxon drill, small flanged bearing and cutter through its centre was used to run round the template and re-cut the new opening.

Nose wheel is now in, mains are awaiting some 8mm dowels to connect them to the retracts. I still need to strengthen the main retract plates before final gear fitment but should have this done during the next few days.

marcs

Migf117

Hi Marc

I did the same thing with the nose gear mounts, I enforced the whole structure in the nose by doubling every part with 6mm plywood.

I'm using the Eurokit retract set but I thought of changing the steering system to exactly what you did. but I my case that was gonna require a lot of machining & a lot of work.
So I ended up using wires............

Tomorrow I the inspection and the first flight... wish me luck guys.

I'll post some pics & may be video if everything went the way it should.

Moatasem

steve2972

My Feedback: (2)

Good luck with the maiden!

marc s

Got round to the CG test today.

The Gryphon uses a lightweight pipe which is around half the weight of the stock unit, a B100F turbine, no full bypass but ducting to turbine inlet, electron retracts, our own e-brakes, stock 2.5L fuel tank, CAT-M bubble trap, 3s 4000mAh ECU lipo pack, 2s 2200mAh (x2) for RX, 1 x 2s 1000mAh for electric retracts and 1x 3s 500mAh for e-brakes.

Not had a chance to get the AUW but we added 170g of lead shot mixed with epoxy into the nose to achieve the CG at 220mm. The 220mm figure was that achieved as the best location from Global who have already flown and adjusted this location.

I was please to add a relatively small amount of nose weight and when its dry I will weight the complete jet.

If the weird weather does not wreck the planned 6th April maiden I will report on the outcome shortly after.

Pic of Gryphon hanging up while epoxy/lead shot in nose cures overnight.

marcs

osvaldopv

My Feedback: (12)

Hi all !

Does Global Jet Club will have this jet available ?, because at the website there is only a picture .

Thanks

Osvaldo

mikedenilin

My Feedback: (67)

Yes, we have some in stock. Contact us at [email protected]

We are working with Robart and Dreamworks on the LG system for USA market. Will upload the photos and information on our website once these developments are complete.

Mike

osvaldopv

My Feedback: (12)

Any videos yet ?

I would like to see her in action before I make a decision on getting one .

Thanks

Rich_C

I video'd the first flight of Marc's plane, will upload the video later,

Rich.

Rich_C

Finally managed to upload the video

http://www.youtube.com/watch?v=jLWVk...e_gdata_player

Enjoy,

Rich.

weazel1

nice video slow take off and extremely slow landing very nice and forgiving it looked like

steve2972

My Feedback: (2)

Looking good

marc s

Hi, yes the Gryphon flew very well, the B100F provided more than enough grunt, early in the video Ali pointed her nose up and he said it just kept accelerating so great performance. Most of the flight was around 1/4 - 1/3 throttle, stall was mild and at very slow speeds, again the video shows this.
Landing was very slow even with a very strong cross wind and the 'ultra-brakes' which had their first true test on the Gryphon performed very well giving a nice proportional feel from the slider on the Tx, hopefully Ali will add some of his initial thoughts on the flying soon, and as always many thanks to his help to put the first miles on this new airframe.

Unfortunately we only managed one flight as the main tank clunk was not picking up fuel correctly so I will need to investigate this before the next flight is made. CG was set at 220mm, Mike from GJC who has had a few flights on this jet suggested this point but for us it was too tail heavy and a bit slushy on the elevators so I will be adding some extra nose weight too before the next sortie.

Finally cheers to Rich for the camera work, and the time to upload the files to Yutu.

marcs

mikedenilin

My Feedback: (67)

Hi Marc

Congratulations on the maiden. I also have some problem with the fuel pick up. I have the CAT and it's 1/2 full after some aerobatics. Let me know how you set up the clunk. The 220 gives me more coaxial roll without a lot of down trim whil fly inverted.

I like the electric brakes too. Please tell me more about it.

Mike

marc s

Mike,

The tank is quite long and thin, my pick-up was done with a short piece of flexible tube close to the filler neck and then a brass tube down to the clunk, this during any nose down flight would such air from the main tank, the fix is two fold in my case, first I am going to re-make the tank so it is full depth, shorten it slightly so it sits inside the wing tube but sits on the bottom of the fuselage, this will increase the capacity to around 3.5L (2.5L original) but also make it deeper so the clunk should be able to follow fuel more easily. I also plan to just use a heavy brass clunk on the end of some flexible tube and do away with the brass tube - I don't see kinking an issue but once done will test.

We have the pattern for the ULTRA-BRAKES for the Gryphon now so PM me and I can talk you through the product.

marcs

Migf117

I Did my maiden flight yesterday............

WOW this plane is the best ever. slow takeoff & slow landing. I had a problem with nose wheel as it didn't open fully so I landed on the mains & then dropped then nose on the grass. No damage. I think the spring is bit weak to open the wheel against the wind. I'll have to take the retract a part & put stronger spring.

1/2 power all the time. the great part is when I deployed flaps (50% & 100%) there was no trim change required at all. the plane just slowdown.

I love it.

Congratulations Marc for your maiden, great flight.

marc s

Running the B100F, with a max thrust fuel draw of around 360ml/min the current tank (2600ml) would last around 7 mins, that's fine generally but as I wanted to tackle the clunk issue I felt a deeper shorter tank would provide a better shape for the fuel draw.

The current tank sits on a ply former deck, above the fuselage base, so a gap below the tank of around 5-6cm is left effectively empty. Looking at the space I opted to carve a new tank shape from some blue foam which was full depth, I had to shorten the rear slightly to give room for the wing tube to pass behind, and also shorten the front to accommodate the nose wheel steering formers which are pre-fitted to the Gryphon.

Once the blue foam plug was shaped I painted on three layers of water soluble PVA, once dry I glassed the whole tank with around 10 layers of glass cloth, 6 or so layers of fine 80g and the rest some 40g cloth. I shoved an aluminium tube in the end where the filler was going to be and used this to hold the tank while applying the glass cloth with the small roller, a method I use on most glass applications.

Once dry I repeatedly flushed the blue foam out with thinners, got through around half a gallon but all come out eventually. Next was to clear the layers of PVA off the inside, I guess the PVA I used was not the easiest to remove, certainly not like the blue tinted stuff we use for the Stinger moulds, so after repeated soaks in warm soapy water I opted for an 'abrasive' method

The wife has a nice tub of green stone chips that are used in the bottom of flower vases, so without her seeing I poured the contents into the tank, added a small amount of water and spent half an hour shaking the tank - finally the PVA was removed and a few flushes later I had a new tank. A few pin holes to seal but very happy with around 3 hours of work.

The original tank as mentioned above holds 2500ml, this new tank holds 3800ml, so now there will be a nice relaxed fuel capacity to float about with. Hopefully the clunk will be able to work better in the space of the new tank, and being slightly shorter is sits closer to the CG although I doubt this will make any big differences.

Next job is to fit filler and vent.........

marcs

Geoff White

Great work again Marc.

TimWatson

Marc likes to make a tank and a nice one it is too

bukeym

Where can we purchase these main oleo struts? We are useing Electron Retrtacts with 1/2" inserts.

BaldEagel

Did I not read somewhere at the beginning of this thread that Boomerang Elan struts and retracts fit?

Mike

marc s

These are the part numbers from Jet-1A for the gear I used on this Gryphon, great service from Jet-1A who helped me to work out the best combo. Speak to Sabine via email at:

[link]http://[email protected][/link]

These items are all for Electron retracts with 6mm diameter pins, so the part numbers will be different if you are using alternative pin sizes.

J125.317 - 60mm diameter rubber nose wheel
J125.203 - Aluminium wheel rim for the 60mm diameter tyre
J125.300 - 74 mm diameter rubber main wheel (2 required)
J125.218 - Aluminium wheel rim for the 74mm diameter tyre (2 required)
J125.992 - 149mm main trailing link legs (6mm shaft version) (2 required)
J125.953 - 145mm nose leg (rearward retracting) (6mm shaft version)

I made two spacers for the mains to make them around 10mm longer, and a similar one for the nose - think the pictures are on the thread, this allowed the wheels to sit nicely in the centre of the wheel cut outs.

marcs

bukeym

Thanks for the info Marc,



I strongly believe that Trailing oleo main legs would really help this jet since it tends to bounce during landing. We will make more flight tomorrow (and a video hopefully) and update the news.

Best Regards

Migf117

steve2972

My Feedback: (2)

Why was this post deleted?

marc s

A PM to him might do the trick.

marcs