I am only loosing pressure when i turn on my radio. If the model sits with wheels down and radio off I can pressure up tp 100psi and it holds that presure but as soon as I turn on my radio the pressure drops to about 80psi and then stabalizes.

I have programmed the Jetronic valve to switch off pressure to the cylindersafter 15 seconds with either gear locked up or down and then I try to repressurise the system with radio on butit will not hold 100psi which is the minimum you need for retraction aftertake off. It will cycle at lest six times in a static situation.

I have a leak somewere so I hope my mods cure it.

Phil.

I had only one medium size air tank for the gear & doors & got the same drop in pressure as you, when I switched on the radio. I think the reason was, the lines & all the cylinders get pressurised at switch on & with the gear cylinders being large, they consume a lot of air. I fitted an additional large air tank, so now have two tanks of air & there is no drop in pressure.

I have my JD valve shutting off up and down after 15sec. I have no loss on switch on!

Dw

I'm just getting ready to plumb the retracts and doors , got a few questions, hope to avoid some of the issues that others have encountered. I've looked at all the electronic valve options and I think I'm going to go with a simple mechanical UP3 valve for gear and doors (any issues with that?)

Also, looks like the air cylinders on the mains will not accept 3mm air line, better suited to 4mm. Most (if not all) valves on the market seem to accept 3mm lines. Are you fellows simply stepping down the size of your lines at the air cylinder with a 4mm to 3mm reducer or is there a way to plumb the whole system with 4mm lines?

Haven't bought any of the hardware for the air system yet so, I'm open to better suggestions at this time.

TIA

Mike

Mike

UP 3 would be a great option. I test flew a Graupner Hawk (same units with scale leg option which are heavy!) today with a UP 3 and the gear worked fine.

I used 3mm festo tube straight onto the nipples...I stretch the tube a little with a phillips screw driver pushed in a few mm. But most have used a short length of 4mm tube then stepped down.

I feel 3mm tube is best through most of the system.

Dave

That's great Dave, thanks for the quick reply!

Mike

I also used a short 4mm tube from each of the cylinder nipples, then fitted a festo 4mm to 3mm reducer.

Just finished my replumb of the airlines on my Hawk with I am pleased to saysuccess.

I have one very large Robart air tank over the fuel tank plumbed into the gear circuit only,and one large BVM air tank each for door and brake circuits,all independent of each other.

I have used 3mm Festo tubing from the gear cylinders and the festo tubing goes on to the large nipples (Ijust love large nipples)as DW has said without any problem as festo 3mm tubing has a larger ID to BVM tubing.

While my retracts were out of the model i filled a small amount of 100wt silicone model car shock oil into the cylindersto lube the O rings.The silicone shock oil softends the O rings and makes them swell a little to give a good seal.

Left all the JDvalves as before and now I can hold 120psi for half an hour with the radio on.

Phil.

Just back from flying mine at Phoenix, gear worked perfectly...even after forgetting my own air pump and not pumping the gear up again for the first flight!! Too cold today once the sun went in, frozen brain!
Should have a video posted later as Paul Baker filmed the last flight.

Dw

Dave
Decided to open the shop today as only two weekends to christmas and work on and off on my Hawk retracts.

Thought I saw your Red Arrows Hawk on the club webcam,bloody cold at 1deg c this morning.

Look forward to looking at the video of your last flight.

Phil.

Phil

Probably a good call, temp was OK, it was the wind chill once it clouded over that made you feel cold. Cross wind too!

Dave

Video today by Paul Baker with gont detail..

http://www.youtube.com/watch?v=6q6V6F38Hio

[youtube]http://www.youtube.com/watch?v=6q6V6F38Hio[/youtube]

Colin

Good job you have the "tech" to put the video in the thread [8D]

Thanks

Dw

[quote]ORIGINAL: Jascat100



Jim

You are right, the valve opens during power up and fills the void. I always pressurise with the radio on

Dave

Gents

I am posting for a friend who is building his Hawk. I am wondering who makes a quality cockpit kit for this airplane? I understand there isn't a drop in unit available and my friend is willing to make it work to fit as long as its quality

any insight is appreciated

Talk with Eric at Jet Central, DerJet Hawk cockpit is what guys use here. It fits pretty good as is.

Dave

i was over a builder friends house today where i saw he building a skymaster 1/5th scale bae hawk for one of his customers .all i can say is that it doesnt even come close to being like the comp arf hawk. the plane feels like you can put your finger through it. the comp arf planes are second to none...

Anyone have pics of the CARF Hawk next to the SM Hawk for size comparisons?

the comp arf hawk is an inch bigger all around. the fuse on the comp arf is more beefier and solid...

Sorry, I was referring to the 1:4 scale Skymaster Hawk, not the small one.

the 1/4 scale looks like a monster compared to the comp arf hawk...

<p class="MsoNormal" style="margin: 0cm 0cm 10pt"><span style="line-height: 115%; font-family: "Verdana","sans-serif"; font-size: 10pt; mso-bidi-font-family: Arial">Have to agree on the comment about SM engineering/quality.

I really like the finish and detail on the SM Arf's - but the engineering, quality of glass work, resin/materials used is FAR superior on Comp-Arf. After seeing the rapid wear and tear and some failures on the SMARF's I am steering well away from them.

I wish Comp-Arf had come out with a model with slightly more scale details - the scoops and scale flap covers would add a lot. I know I can add them myself but I wanted an ARF... my building time and skills leave much to be desired. I cannot justify/afford a Skygate etc kit even if I had the skill and time to build. Something a little more scale (along the lines of Jet Legend) would be great.

I am adding a lot of stuff to my Comp-Arf Hawk this winter. I got the Der Jet cockpit and I'll putting on some of the antennas, strakes etc... The tail pipe fell apart on me (I never would have imagined it but just being heavy doesn't mean well assembled!) I got a TamJet pipe that's 12 oz less! Now a lot of the lead in the nose can come out too.

I love my Comp-Arf Hawk. I wonder if anyone will ever come out with some scale accessory parts like the scoops, flap covers, more scale strakes, etc...?</span></p>

A guy in Germany is supposed to be offering them all, but I'm still waiting for the sets I ordered! I'll chase and see if it's really happening.

Dw

I have both the SM 1/5.5 Hawk and the CARF. The SM looks really nice, perfect paint and has a lot more scale details. The glass work on the CARF is much better, the engineering of CARF is much better and the CARF landing gear is much beefier and a superior design. The CARF Hawk is also quite a bit more money than the Skymaster as well when u add in all the extra's that you have to buy with the CARF . The CARF is bigger, another 4 inches or so longer and more span on the wing and stab. I haven't flown the CARF yet so, can't make any comparison there.

From a build perspective, the CARF was a pleasure to build, the SM an aggravation. Everything on the CARF fits.

Mike