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Fast plane - slow flight - would you?

A friend of mine flies a Columbia 400.
She is part of a group that will be flying a loose formation during several hours.
There are some really slow aircraft in the group and the expected cruise is going to be 100 knots.
She is concerned about the ability of her hot rod engine to cope with such low power settings and unusual cooling parameters for several hours.
Any ideas? Thank you

LSGG, LFEY, Switzerland

What will be the % power setting? 55% should be ok (economy cruise?) but 30% is probably no good even if it can maintain level flight…

On cooling you will be able to monitor oil temp and pressure or cylindre temp as you should do in fast cruises?

IMO 100kts is already fast enough to get air or water cooling themodynamics to work in most SEP aircrafts, so the question is mainly on engine power setting

Last Edited by Ibra at 09 Mar 09:43
Paris/Essex, France/UK, United Kingdom

I have not done this so I am only guessing but it should not be a problem as long as she is monitoring the temps. It will be a very low power setting so that should keep the temps low.

ESSZ, Sweden

These piston engines liked to be flown at 65-75%.

Oxford (EGTK), United Kingdom

I think it will be fine, for a few hours, provided you give the engine a good high power run on the next flight, due to my experience here.

100kt will be around Vbg and probably about 40% of max rated power.

Administrator
Shoreham EGKA, United Kingdom

100 knots is really slow for a C400, It’s the same speed as the traffic pattern speed just before turning base (with TO Flaps !).
I think she is correct in feeling concerned about the power settings and cooling if you have to fly this speed for a long time.
I would not feel comfortable especially not in formation. You practically have to fly with Flaps down (T/O) to maintain some margin.

Last Edited by Charlie_Alpha at 09 Mar 10:21
Charlie_Alpha
EHBD, Netherlands

As always, it is all in the POH and if a pilot is concerned, I am more concerned about the pilot ;-). I never flew a COL4, but the T240 with recommended cruise from 45 percent power up (145 KIAS at 2000ft) I would not take that slow for an extended period – too close to bank stall and fairly buttery soft on the controls that slow, cooling wouldn’t be my major concern, insufficient heat and plug fouling may. On a formation flight I would split groups on more similar fast planes. Let the COL4 be the scout plane and arrange barbecue for the others at destination.

Last Edited by at 09 Mar 10:22

The poh speed figures for max range or endurance speeds are between Vbg and Vms these are typically higher than Vs1 and Vso for certified SEP aircrafts (max 60kts), I will just fly the “approved max range/endurance profiles” as it has been demonstrated by the aircraft manufacturer for 6 hours

I did that few times in a C172 going London to Bergerac while watching T&P, on a dry rent it comes very cheap on fuel (not sure about cost or benefit in maximising a Lyco engine life beyond 2000TBO but it is within poh), it does work but very boring and forward view is crap…

Last Edited by Ibra at 09 Mar 10:38
Paris/Essex, France/UK, United Kingdom

Used to fly a Robin DR400/180 at 100kts in loose formation. (Yes I know its a vastly different aircraft , but its part of my point)
The Robin was ok at that, the fuel burn was extremely low but it just didn’t feel nice, it was easily upset in moving air.
I can imagine a slippery airframe being very hard work. If loaded with fuel and pax I’d probably decline.

United Kingdom

You should ask this lady pilot to join EuroGA. We need more of them to balance out the blokes

Administrator
Shoreham EGKA, United Kingdom
43 Posts
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