A2 Straight tow wing warps

[Anonymous]

I’m thinking of building Andrew Crisp’s Flashback (or Millenium Flashback) for straight tow this summer. Since tight circling isn’t an issue, in general terms would you keep both center panels flat and just use washout in the tip panels (i.e. 3mm left and 5mm right)?

[Lee Hines]

Huey,
IMHO, I am fairly sure Andy would use some washin on the inboard main panel to counteract spinning from thermal action.
That differential tip wash trim never worked for me, or most of my fellow A2 fliers, unless it was for calm, flyoff type conditions only.
It would be nice if Andy would answer this directly…
CIao,
Leepero

[Anonymous]

Thanks, Leeper. I have one of your Dragmasters waiting to be built…in storage until we move this summer. Did you put washin on the inner panel for the earlier straight tow machine? The Flashback, methinks, is a bit lower aspect ratio than the Dragmaster.

[Peter Brocks]

Huey,

I feel sorry for the folks that live north of here in the cold and still can’t go flying. Here in Arizona it soon will be too hot to enjoy flying.

In order to have your right circling glider “seek” thermals you want to have a wash-in of not less than 0.6mm in your right center panel. That is the trailing edge of your right wing is 0.6mm down compared to the left wing trailing edge. This is the same as having 0.3mm wash-in in the right center panel and 0.3mm wash-out in the left one.

I just looked at Andy Crisp’s Flyright #2 glider in the FFn 12 from 1997. It is an F1A with a wing span of about 2,000mm. There he specifies a right-hand tip wash-out of 3mm and a left tip wash-out of 5mm. Lee is again right – most gliders now have about 1mm less wash-out in the right wing tip compared to the left one.

Peter

[Anonymous]

Hi HueyD

I spoke to Andy yesterday about the M Flashback and it’s warps. (I don’t know if you ever built it?)

Interestingly he said that it had NO washin at all, just the assemmetric washout on the tips. He did say that each model is different and you will only know for sure when you get it out and fly it. . .

FWIW I agree with the Leeper about washin. Although Ray Monks was almost evangelical in his ‘no washin – it kills performance’ stance I think a bit of washin helps in turbulent or thermally conditions and I always use a small ammount on the starboard inner (for a model turning right).

I watched a well known flyer who had just returned from Lost Hills last year flying an electronic bunter that had been set up for ‘best glide’.The same model stood on its wing tip and spiralled in to the ground from @ 200′ when gliding well which we put down to lack of washin to hold the inner wing up in the tight thermal it encountered.

All the best
Paul

[Anonymous]

Tis true, you need different warps at Lost Hills to the UK (and different again for Scotland). With an electronic model you can program the lot without difficulty but it is best to not overwrite the UK data when in the US !

Yours looking forward to the rain next week,

CHE

[Bill Shailor]

Back when we were flying Happy Hookers, the trim was to carve each main panel flat and then add washin to the inboard panel during trimming. This was accomplished by packing the inboard main panel down. Since this panel rotated on the wing joiner wire, we could add shims as needed. Usually, this worked out to around 1/64″ washin. This seemed to help in still air glide as well. It made the model a little more “wandery” in the calm weather.

[SIMON BLAKE]

I built a Flashback a while back and have a few flights on it. I set it up exactly as Andy said in his Aeromodeller article with one-eighth washout in each tip and both centre panels flat. I have only flown it a few times, but it few virtually right off the board — it’s been the easiest to trim glider I’ve built. (In 30 years I’ve built three. I’m a power flyer.) The only change I have made is to move the towhook back about 1/8 and I have just a touch of left rudder.

[REYNOLD MAZZOCCO]

@Peter Brocks wrote:

Huey,

I feel sorry for the folks that live north of here in the cold and still can’t go flying. Here in Arizona it soon will be too hot to enjoy flying.

In order to have your right circling glider “seek” thermals you want to have a wash-in of not less than 0.6mm in your right center panel. That is the trailing edge of your right wing is 0.6mm down compared to the left wing trailing edge. This is the same as having 0.3mm wash-in in the right center panel and 0.3mm wash-out in the left one.

I just looked at Andy Crisp’s Flyright #2 glider in the FFn 12 from 1997. It is an F1A with a wing span of about 2,000mm. There he specifies a right-hand tip wash-out of 3mm and a left tip wash-out of 5mm. Lee is again right – most gliders now have about 1mm less wash-out in the right wing tip compared to the left one.

Peter

Working on a Sija (mechanical and no WW). When you say “not less than 0.6mm”, how much would be too much, or even better, what should I aim for?

Thanks,

Rey

[Lee Hines]

Hi Rey,
The amount of washin needed for A2s is somewhat dependent on its
wingspan. I cannot recall what Sija span is.
Shorter ones can carry more, since they will normally be used for
thermal conditions. Let’s say up to 1.5mm washin differential, if washin
is built in or warped in.
A bit less if full wing half has been moved for washin.
Too much washin usually causes launch troubles. Essentially rolling the
glider away from the desired tow direction, due to aileron effect.
In that case reduce washin just enuf so that combination of washin and
rudder cross-control gives desired rollout.
Some testing and juggling is usually needed to determine how much
of each is best trim setup.

Good luck and let us know how it works out for you!
Leeper

[REYNOLD MAZZOCCO]

Thanks, Lee.

It is 2100 mm. I plan on twisting the whole wing like on my MaxMaster using the same system so it will be adjustable. Start with 1mm and go from there? Since I am still a rookie at towing, less sounds safer.

Rey

[Anonymous]

Hi Rey

I was chatting to Andy about his method of trimming (and the Flashback in particular earlier this year) He starts with differential on the tips and adds washin as required (Sometimes needed to add some to stop the model spiralling when launching) He emphasised that each model is different though. . . . 😆

Checking through my own (similar type of models) I normally end up with between 1 and 3 mm of washin (the model with 3mm is a rough old model with a tight glide turn for windy weather)

I’m putting together a ‘new’ model for next year and will start with @1 1/2mm of washin and 3mm washout on each tip – hopefully that will give you some idea.

Incidentally I like to use tail tilt to help the turn because it is not as speed sensitive as rudder alone 8)

Hope that helps, let us know how it goes
Paul

[REYNOLD MAZZOCCO]

@DaddyO wrote:

Incidentally I like to use tail tilt to help the turn because it is not as speed sensitive as rudder alone 8)
Paul

Thanks for the info. on wing warps. Matches what others are saying.

As for above, is it very common to use tail tilt on A2’s? I can see where it might help keep from spinning out of a big thermal, but are there cons to it? With the small stabs and forward CG’s, it would seem to take a lot of tilt to be effective.

Thanks,

Rey

[Anonymous]

True enough Rey, but the Flashback and my own models are a bit ‘old fashioned’ with larger than currently used tails and shorter moment arms; hence my preference 😕

Only con as far as I am aware is it can look a bit odd – I usually end up with @1/4″ or so on this size model.

(Using T Tilt is a habit I acquired when trimming A1’s for the zoom. The smaller class can be a bit speed sensitive when it comes to launching and I found it was an easy way of controlling this. . . . maybe it’s now a habit I can’t break!) 😳

Cheers
Paul

[Dean McGinnes]

The original question was about straight tow A2 Nordic (oh how I much prefer names to numbers) Gliders.

However, it seems that many of the replies are refering to circle tow bunters. Please clarify that we are talking STRAIGHT TOW here.

Sorry for shouting. 🙂

[Author]

Posts