Minimax question

[The Baron]

I have purchased a partly completed minimax low wing aircraft i noticed it has wash in in the wing instead of wash out is this the norm or has it been stuffed up? thanks in advance, Steve.

 

 

[IBob]

I have purchased a partly completed minimax low wing aircraft i noticed it has wash in in the wing instead of wash out is this the norm or has it been stuffed up? thanks in advance, Steve.

If it's also got anhedral, you could try turning it over???

[Head in the clouds]

I have purchased a partly completed minimax low wing aircraft i noticed it has wash in in the wing instead of wash out is this the norm or has it been stuffed up? thanks in advance, Steve.

I've had a look through a few pictures of Minimaxs and it looks like they have washout, as you'd normally expect, unless they had a radically different airfoils section at the tip compared with the root, which they don't appear to have.

So you're saying yours is rigged with a greater angle of incidence at the tip than at the root? If that's the case it might be rather nasty for tip-stalling, i.e. the tip of the wing stalling before the root and the usual consequence, at the normal stall, would be loss of aileron control with wing-drop/incipient spin entry.

 

Depending on how rigid the wings are in torsion you may be able to shorten the front struts to give the wings washout, or lengthen the rear ones ...

 

Soleair, a member on this site, has quite recently completed his Minimax build, if you send him a PM I'm sure he would be able to tell you much more about it.

 

 

[bexrbetter]

Doesn't sound right.

 

I just shot an email off to Dave Cooper for other reasons, but have included your inquiry.

 

 

[microman]

Definitely not right - I just completed a HiMax (same wing) - as I recall there was approx 1 1/2 deg of washout required in terms of the plans. HITC probably has the right idea - either shorten the front struts, or lengthen the rear struts (as I recall the rear strut is sleeved at the wing attach point to allow for adjustment) and you should be able to get enough movement to produce washout at the tips. Sorry IBob, but its nothing to do with dihedral and anhedral !

 

 

[IBob]

Sorry IBob, but its nothing to do with dihedral and anhedral !

Microman. I was being a smartass...........................

[The Baron]

I've had a look through a few pictures of Minimaxs and it looks like they have washout, as you'd normally expect, unless they had a radically different airfoils section at the tip compared with the root, which they don't appear to have.So you're saying yours is rigged with a greater angle of incidence at the tip than at the root? If that's the case it might be rather nasty for tip-stalling, i.e. the tip of the wing stalling before the root and the usual consequence, at the normal stall, would be loss of aileron control with wing-drop/incipient spin entry.

Depending on how rigid the wings are in torsion you may be able to shorten the front struts to give the wings washout, or lengthen the rear ones ...

 

Soleair, a member on this site, has quite recently completed his Minimax build, if you send him a PM I'm sure he would be able to tell you much more about it.

[The Baron]

Thank you guys

[bexrbetter]

The word direct from Dave Cooper's mouth himself is ZERO washin/washout.

 

 

[Soleair]

Sorry, I've only just picked up this thread.

 

The plans for all mid-wing Max's call for zero washout. The ribs are all identical, and the wing is built on a flat table to ensure no twist. The aileron is cut away from the completed wing, so no reflex in that, either. I don't know about the high wing version, but you can download the plans free from TEAM's website, & check what is called for.

 

As has been suggested above, you may be able to achieve the design zero washout by adjusting strut lengths.

 

As to flying characteristics, whilst I have not strayed far from the prescribed envelope, I have never found any tendency to drop a wing at the stall, provided rudder is straight & engine is on tickover. The Max is great fun to fly, & very well behaved.

 

Feel free to pm me, Steve, if you have other Mini Max questions. And I'm assuming you know of the Lonesome Buzzards Max forum - a great resource.

 

Error - ETLB Squawk Forums (edit: I don't know where the 'error' came from, but the link works)

 

Bruce

 

 

[The Baron]

Thanks Bruce for sorting that for me. Do you know where the designated c of g is so i can hang test it i have no plans for it and i haven't got a printer so i can't download a set of plans mine is a low wing with a 503 on it it did have a Jabiru 1600 on it.cheers, Steve.

 

 

[Soleair]

No worries Steve. I hope you can sort the wing twist.

 

CG for all Max's is between 21 - 30% of the wing chord. With a 54" chord, this equates to 11.34" - 16.2" back from the leading edge of the wing. Anecdotally, these planes are said to fly best with an aft c.g. Mine is pretty much full aft, as I fitted a (much lighter) MZ202 engine in place of the 503 it's designed for. I had to use a 2nd battery in the nose to ballast it to get the c.g. forward enough to reach the 30% condition. I've had no problem on stalls, so seems safe enough full aft.

 

If you go here: Support you can download the flight manual which gives all the c.g. & flight envelope details.

 

Bruce

 

 

[The Baron]

No worries Steve. I hope you can sort the wing twist.CG for all Max's is between 21 - 30% of the wing chord. With a 54" chord, this equates to 11.34" - 16.2" back from the leading edge of the wing. Anecdotally, these planes are said to fly best with an aft c.g. Mine is pretty much full aft, as I fitted a (much lighter) MZ202 engine in place of the 503 it's designed for. I had to use a 2nd battery in the nose to ballast it to get the c.g. forward enough to reach the 30% condition. I've had no problem on stalls, so seems safe enough full aft.

If you go here: Support you can download the flight manual which gives all the c.g. & flight envelope details.

 

Bruce

Thank you for that Bruce much appreciated cheers Steve

[Markdun]

I too have built and flown a low wing Minimax, but with a 1/2VW engine. It had zero washout as per the plans and CoG was in the mid range. The aircraft was at the designed empty weight. The plane was easy and a joy to fly and was very forgiving, but being open cockpit it was bloody cold and one got wind burnt on any cross-country. My Minimax had over 30l in additional fuel in wing tanks (& when full made climbs kinda slow, or more accurately slower than the already slow climb rate), an 'Occy' strap trim on the control stick, and it cruised around 60 kts (65kts if you porpoised). It did climb like a rat up a drainpipe in a thermal. ...Stall speed around 20kts! It definitely fitted the bill of maximum fun, minimum cost (pity ra-aus didn't stick to this ethos).

 

 

[Soleair]

Good to hear from another Max builder/pilot, Markdun.

 

I made both enclosed & open canopies, so I can choose whatever suits the season. My MZ engine puts out a conservative 60hp, while weighing 40kg, so I have good power loading (around 11lb/hp with 40 litres of fuel). My climb rate is around 1000 fpm. I have been careful to reduce drag with fairing whatever I can, & it has given me quite a good speed range. I cruise around 80mph, and stall about 35 mph - maybe a little less with flaps. As well as being a lot of fun to fly, these little planes can get into very short strips. You probably found you can do some very steep sideslips, which give an impressive rate of descent. Very handy for getting over trees bordering a short strip.

 

Here's mine at Mudgee.

 

Bruce

 

 

 

 

[Mini-max]

I have purchased a partly completed minimax low wing aircraft i noticed it has wash in in the wing instead of wash out is this the norm or has it been stuffed up? thanks in advance, Steve.

How did you go with your build