digitech

My Feedback: (10)

i am building a starjet
i am powering it with a 75N proto engine , engine weight 850 grams
the thing i dont understand is that it seems i have to like install a huge amount of lead to get the cg right.
i have the engine mounted as far forward as possible.
i use as cg 510mm following the leading edge measured from the middle right?
still i have to like install 10 3600mah cells all the way up and still is to heavy on the back.(see pic)
anyone else have this problem?
tank is on spot of the cg empty
UAT is full and in front of the fueltank
landing gear retracted inside the wing and nose.
i have been reading all the things on the forum , but it seems no one has this problem , since most had or have it powered with sophia,s
Ram,s etc etc.
tips anyone?

747drvr

My Feedback: (5)

Hi Sandor,

I've read that they do need nose weight . I guess you do what you have to do to balance it . You may try mixing epoxy with lead shot and pour it right in the nose to make the most use of the weight . I've had my kit for 5 yrs now and would like to start work on it again ! I have a Wren Supersport coming for it . Should be a good combo . Will your struts work with Springair gear ? I may order a set.

Marc

jason

My Feedback: (1)

Hi Sandor,

I had a Starjet with a Wren in it and as well as having all the nicads up front it needed a fair bit of weight ( about 5oz if I remember right) epoxed in the nose to get the C.G right . I think the Starjet is a great flying plane and if it wasn't for the time it takes to build and re engineer the thing I would definatly have another.

Don't forget to strenthen the tailplane spar!


Regards
Jason

digitech

My Feedback: (10)

thanks for the reply,s
i have indeed put a lot off weight in it to get the cg right.
as for the tail section i know about this problem , actualy i solved it with lots of carbon cloth.
i had to rebuild the wing to get this gear in.
the retracts are simple double actions.
i used our jet-1a and had to shorten them by a inch to get them fitted.
the wheels are braked and are 60mm in size.
the tank is a composite one and holds 2.2 liters
i got the weight to 6.5 kilo,s in total together with the 75N little engine it should run ok.
we will try to have it done before this coming weekend to show it off...

rcguy!

My Feedback: (69)

That clears things up a bit....1oz in the tail equals 3 or 4 in the nose?

What's this secret turbine ole buddy?

Dave

David Gladwin

My StarJets used to be powered by JPX 260s and needed a great chunk of lead in the nose to balance. My remaining SJ (one was sold) was powered by a RAM 500 (now deceased !) and was ballistic and required no lead in the nose. It will soon be powered by a Wren Supersport. The trick to getting the correct balance without ballast is NOT to put the elevator servos in the stab, but mount them at the rear of the fuselage with the rudder servo and connect with well braced cables. This has the added benefit of maintaining the strength of the stab as there are no cutouts for the servos. Works for me and the SJ, now nine years old, is a superb flying machine.

Regards, David Gladwin.

I would also suggest that great care is taken with the integrity of the control system to minimise flutter onset. The laminar flow wing and very slim cross section makes the Starjet a very slippery machine indeed but one which can be slowed right down for landing (with very docile handling ) if one uses crow braking. I use almost 80 degrees of flap with about 10 degrees of aileron upset. My guess is that this machine would fly very nicely on athe new Wren Gold 44. It would be very light requiring only 1 liter of fuel and the JPX 260 did not dleiver much more thrust than the new Gold 44 (about 11-12 pounds), total weight saving around 4 pounds.

747drvr

My Feedback: (5)

Hi David,

You might recall we communicated about this plane years ago ! I have a Supersport coming now and finally want to get started on it again . With so many shiny new things popping up it takes some discipline to realize that the older stuff that is not so "cool" anymore flys just as well or better !

Can you give more details about the cable method ? I've been hearing about tail failures and was concerned about putting servos in the stabs . Do you use pull-pull on the rudder ?

Marc

Big Tony

I have a AD starjet with a wren supersport in and its superb u need to do alot of strengthening across the spine of the fus just incase and the stab spars. I've put jr slim digi' in the tail halves and only have a very small amount of lead in the nose to balance. Weight is about 12lb and carries 2lt of fuel for a good 8min flight.


Your'll love it.

Ant

David Gladwin

Hi Marc,

Can't do any photos as I am in London for the summer (plus 33, makes me feel quite at home) and the model is in Sydney.

I do indeed use pull/pull on the rudder and steel cables, plastic tubes (Sullivan) for the elevators. The tubes are anchored just behind the servos and at the fuselage exit to minmise slop. Also line the fuselage aft end with litho plate and insert a short steel pipe during start so if its hot/wet it doesnt burn off the overhanging stab. Works very well and as you say this is a super model. Will also try the Super Sport in my BVM F16, should be the perfect engine for it, light and very powerful.

Really don't like the thought of servos IN the stab. compromises the strength and stiffness and moves weight aft !

Regards,

David Gladwin.

Big Tony

David,

My setup seems fine - it took a fair few flights with a simjet 3000 before I put a ss in- there aint no way the carbon laminate spars would give up and the weight (12lb total) is fine flys vvvvvveeeeerrrrryyyyyy slow on landings.

All the best

Ant

747drvr

My Feedback: (5)

Thanks for the info guys ! Only 12 lbs with a Supersport ! That would be another good candidate for the new 10 lb 44 Gold . I just put the 8 lb Gold on my 11 lb dry Stingray , and it goes very well ! My friend Gary just installed the new 10 lber in his L-39 . I now have powerplant envy !

Marc

Big Tony

This pic is when it had the 3000 in it weighing in at about 15lb with half a church roof in the front.


Ant

GoeKeli

My Feedback: (18)

How much work is it to build the starjet? Looks very interesting Ant. Are the control surfaces already cut?

Joe

Big Tony

Quite alot of work but well worth it.

Ant

GoeKeli

My Feedback: (18)

Starjet people,
I just got a kit today!!!! I would like to use a Wren Supersport. Looks like a considerable amount of work, so I'll take it a job at a time and not get myself overwhelmed. What retracts are you all using? The plans say 300 series and the website says 101HD. I'd like to use oleo struts and BVM sport wheels/breaks. The plane I have looks to be reinforce in the aft and verticle stab with carbon weave. This thing must really honk with a 14lbs motor but not a lot of room for fuel. The wing is a work of art. I can't wait to see it glassed and painted. !~)


Joe

digitech

My Feedback: (10)

i got a 2 liter fuel tank inside
for the wren SS that is more then enough!

cmjets

Hi friends:

Where you get the Starjet kit?

When you get it?

Thanks.

____________________________

Carlos.
____________________________

.

GoeKeli

My Feedback: (18)

u kaashoofd,
What 2L? A soda bottle or jettech? I have an old rookie 80oz but it will not fit.




Carlos, there was one for sale a while back here on RCU. I talked to the owner several times after his add expired and after reading so much intriguing information about the plane, I bought it from him.

GoeKeli

My Feedback: (18)

Are these the servo covers for the ailerons and flaps?

John Wanner

My Feedback: (17)

Those are push rod covers
Use spring air on all three landing gears.

GoeKeli

My Feedback: (18)

Thanks John! What model springairs?

Any ideas what these parts are? Jointers or spars? I am looking for the wing jointers and stab spars.

Joe

MrScott

2 of the pieces are used to hold the wing together..

If you look a the 2nd pic in the 1st post,

The block in the middle is what the 2 forward wing bolts pass thru
The wedge shaped block is what the single wing bolt passes thru
It's been a few years, but I believe the stabs on the one I built had a slot cut for 3rd piece in your pic

at least that's the way I used them..