johnnychimpo

I have my vipers trimmed after about 10 or so flights and it seems that the elevator needed about 1/16 to a 1/32 up elevator to fly strait and slightly down. Is this too much or should i re check the incidence. I figured that it was because of the fuel. I am not using a CG tank, just the one that came with the it.

The ailerons needed some right trim but only enough to get the outboard part of each aileron flush with airfoil so i dont think there is any problem there.

P. Johnson

My Feedback: (1)

Scott, double check the incidence and also see if this is a "power on" issue, The problem could be an engine incidence issue.

Vendata

Scott Put In A Shim Between Engine Mount & Fire Wall.

Ed Smith

It is nearly always necessary to trim the airplane to suit ones flying style. this can be done only by flying the airplane and making adjustments. If all of the incidences are correct the elevator offset could be trying to correct a balance issue. This is normal. It is possible the airplane is nose heavy and up elevator is correcting this. Do not shim anything, if the incidence is correct why mess it up? The easy way to find out is to shift the balance point back. It is a bit of a chore to keep removing the wing to shift batteries or tank while at the flying field. So, take a pocket full of quarters and some sticky tape next time you go flying. Tape a quarter on the back end of the fuselage, fly it and note the difference. Keep doing this until the airplane wants to climb, then take out the up trim. I think you get the principle, it may take several flights. 10 trim flights is really not many when it comes to setting up a racer. When you get home check the balance point of the airplane remove the tail weight then move stuff around inside the fuselage to duplicate it.

I emphasise that the three incidences have to be correct first. It is then a case of adjusting the balance of the airplane to get it fly the way one wants rather than carrying control surface offset. Control surface offset will really mess with the aircraft in knife edge flight.

Scott, if you want some help look us up in Lucasville I will explain the whole thing. I will be there Friday for some practice.

Ed S

johnnychimpo

Great Ed, ill be there on firday afternoon

Ed Smith

Scott,

If for some reason we are not at the field (Bad Weather) we are staying at the Super 8 hotel. about minutes further south on the same highway.

Ed S

GRANT ED

Let us know what you find. My viper does the same thing. I have the CG set as per the manual. I was going to look at engine thrust angles and wing incidence but have not had time, the plane only has 3 flights on it.

johnnychimpo

the incidence is correct. Everything is at 0.

I have had 3 vipers now and they all are the same. 1/32 up elevator.

[email protected]

shimming won't fix the problem, it actually makes it worse! I suspect its the vee tail seat / vee block that is wrong. I have two vipers and the vee seat varies. Easily cheacked by setting up the tailplane on the bench and creating a new datum line on the vee block. Both of mine have been reset and the models fly perfect with no up on the elevator. I actually have glued my tailplane in place to hold the thing correct. An extra 5 minutes fixing this is worth it. Further, the cg is exactly as the instruction book- 3 inch from the L.E. Never forget that a vee tail will look wrong when in fact it is correct......its to do with the taper on the fuselage and unless you create the correct datum the chances of getting it wrong can be quite high! regards trevor h.[:@]

John Z Williams Jr

Hey Trevor, are you the prop guru??? I have been reading your articles on supercoolprops.com .
You have some great articles.
Do you know if Ranjit Phelan has an email site? I would like to ask him some questions on fai...

Thanks, John Williams

[email protected]

It is I....yes I have been making props for a longtime and the airborne magazine/ john hughan's website has had some articles that I have written. Props are an interesting subject - but there are some very good prop manufactururers close to you - ed smith as an example.
Ranjit Phelan has no email - when he lost his thumb he lost the abnility to type-but if you want to email me I will pass the questions on. I called for Ranjit at the f3d w/c in Austria in 93, czech in 97 ans sweden 99....ranjit has been runner up w/c in 93, and prior to that about the 1985- in the usa at chicopee if my memory is correct.
although he and I live in seperate countries - australia/ new zealand we had spent a lot of time together and understood each other very well. Even Ed Smith knows us in person!
kind regards trevor h.

John Z Williams Jr

Thanks, I will address my questions through you... As far as Ed goes, he is my sworn enemy....
I like mallets: he does not...
I will explain later, I will send you an email soon, thanks
JZW