OT ish Really interesting automobile engine.

[Biggles]

Interesting - I've towed with a Pawnee 235 and, once the post-release 10 seconds had been dealt with (and the CHT was below 200, I think) then there was no need or recommendation to do anything other than fly it. I can't recall the descent power settings or speed but the aim, as with all towing, was to get back ASAP while controlling the rate of cooling with power/speed, going no faster than Va (a bit of loading helps) and keeping eyes out. The ROD was "adequate" without sideslip.

The view in the landing attitude was unusual, but very good compared to some tailwheel types, so no unnatural actions are needed.

[harryagain]

If you close the throttle and dive at the ground after glider release (as some of our nutters did), the barrels are overcooled. The pistons of course are at their hottest as the tow has been at full throttle. So the piston/barrels clearances are reduced. I heard of one siezed up, apparently it had a recent overhaul and clearances were already small. Worst effect is in cold weather ofcourse.

There is no means of controlling the air. So either sideslipping or a more gradual descent reduces engine wear. It was apparently even worse years ago when oils were less good. So we are talking about sideslipping all the way down, nothing to do with the landing.

Cylinder head temperature is no guide, it lags far behind what is actually going on.

Gliding clubs are full of nutters as I expect you know. It was nomal at our place for the tug to find a thermal and circle in it with the glider on tow. When the glider released, some tug pilots rolled into a vertical bank wich became a near vertical dive. At least intiially.

[Biggles]

Sorry, there are several incorrect assertions in your reply but I'm not going to continue the discussion. My statements have been based on considerable personal experience and engineering knowledge, rather than hearsay and bar talk.

[Part Timer]

Thanks for that info - I appreciated reading it! I wonder what the power and torque curves are like on a rotary like this? Can't be very free-revving in a car can it?

[harryagain]

Just stuff you haven't heard of.

[Biggles]

Aaargh, I really shouldn't bite but ...

Despite several thousand flying hours in hundreds of aircraft types and a range of flying operations (including 1000+ tows) there is no doubt that there are many things that I have not heard of. An unfortunate aspect of life is that we don't know what we don't know! The aviation experience is coupled with Engineering Degrees and Fellowship of professional bodies so there are (probably) less unknown unknowns than usual and I suspect that, in this particular case, mine really is bigger than yours ;-) But now, I'm going to stop waving mine so pease do the same.

Back to DIY, and no more responses from me on this topic!!

[Andy Burns]

YAAICM£5

[Nightjar]

On 25/03/2014 11:58, Biggles@flies_undone.com wrote: ...

Welcome to Harry's world, in which, no matter the weight of opinion against him, he will never admit he is wrong, even though he usually is. If you overwhelm him with incontrovertible facts, he will ignore them and start insulting your intelligence.

Colin Bignell