[Rod1]

I have some experience with Jodel/Robin aircraft with flaps or airbrakes. A friend of mine is looking at a Jodel 120D which has neither. The stall speed is 30kn (according to the last test flight). I assume speed control will be more critical and the view on approach will be reduced? At max all up weight will it float forever or is there very little difference?

Thanks,
Rod1

[ak7274]

Have you tried the LAA or Jodel forums Rod?

[Genghis the Engineer]

I did an evaluation on a 120 not long ago for our syndicate, when we were thinking of buying one.

Didn't float, easy to see over the nose, even at my elevated 5ft6". A real pleasure to fly, and I'm sorry we didn't go for one. I'd take the indicated stall speed with a pinch of salt, aircraft in that general bracket you should really treat the ASI as "indicative".

G

[MichaelP]

I remember a group member saying the Jodel dropped a wing when it was slipped.

I flew with him and determined that he was stalling the aeroplane on the final approach.

30KIAS is somewhat slow, I wouldn't believe that.

Jodels such as the D150 that have flaps do not have a significant increase in descent, or lower nose attitude.
A bit like the Cessna 120 vs 140.

The Jodel with airbrake version was better.
I wound Brendan O'Brian up once in G ATLB as I controlled the descent using the airbrakes glider style (just playing silly bug gers), he said "Since when do you put the flaps up and down like that on finals?"
"These are airbrakes" I replied.

[ak7274]

I have a D117 which has virtually the same characteristics as a D120. They do indeed stall at a much slower speed than one would expect. The stall speed is stated at 26kts on mine and it is not a long way off that. Last flight test gave pre stall buffet at 33kts and nose dropped at 27.
We have D120s at our airfield and I find them just about the same.

[ChrisRowland]

There's some data on the D120 on the LAA web site, the ASI position error is high, especially at low speeds. 50km/hr indicated is 77km/hr calibrated.

[rohmer]

Speed control is everything. I believe my D117A performs similarly to the D120 so I suggest flying the circuit at 60kts and once on final, if the conditions are benign, re-trim to 40 kts (45-50kts if the wind is strong/gusting), side-slipping to control the rate of descent and be ready to feed in power as any sink comes on. This gives a ground roll of 150 - 200m. In calm conditions mine will float for ever at 45kts. Mine is an -A model but I only tend to need the airbrakes in calm conditions and at short strips.

[pilotbarry]

Chris' comment about the ASI position error is also true on my 1051.

[Rod1]

“Have you tried the LAA or Jodel forums Rod?”

Is the LAA forum still going?

Could you point me to the Jodel one please.

Thanks for the advice folks

Rod1

[Kittyhawk]

The forum is certainly still operating, but there is information in the english version of the Type Data Sheet here

It recommends an approach speed of 46kt IAS.
By my calculation Vso is 27kt IAS and 1.33 Vso is 36kt IAS

[pilotbarry]

Jodel forum on yahoo. Very active.
Also Facebook pages, pretty active, too

[Joe Dell]

Anything under 40kts indicated on approach is likely to produce an excessive sink rate. So VSO won't work . The aircraft will sink like a brick before it even thinks about stalling. Anything over 50 on approach is speed you don't need.

[PeteM]

I cannot add anything specific to a D120. My Dr250 has small trailing edge flaps. Without using them yes it floats. The stall warning goes off at 50kt and at high weights that is close to the stall. Anything more than 60 and a smadge and ground effect makes for float. The tail wheel first method described in the handbook makes perfect sense under these conditions. Saving a higher rate of sink by having a greater angle of attack

[thegasguy]

I have had a long and sometimes acrimonious, post going on the technical forum re ASI error and approach speed in my D117. Please feel free to peruse.
The characteristics of the wing and having no flaps or airbrake can lead to an un-stalled but very rapid descent if speed decays below 40 knots indicated ( on mine). You need to have flared and be just above the grass by this time.
The actual stall I take to be just under 34 knots, as that is the indicated speed at the (just beginning) of lift off.
I use 65 knots turning off base, slowing to 55 on final and then an absolute minimum of 43 on ultra short final.
Below this mine has insufficient energy to flare even with smoothly applied max back stick.
Actually that's not accurate - it rotates nose up, but still keeps the same path through the air and ' carrier lands-on' quite firmly.
Having a puff of engine on to the end is vital ( for me) as it limits the sink, gives me a means of descending slightly more by taking it off as well as stretching the approach by putting a bit more on, and finally let's me get a very positive 'landing on' and "stick on" when I close the throttle after flaring.
All very necessary at our short, tricky, strip.
The ' problem' is, its easy to end up well on the wrong side of the drag curve by using more throttle than that - dangerous.
For the record, mine doesn't drop a wing in up -to a max rate slip - thank goodness or I would go around a lot.
Also visibility is superb on approach - if it isn't, you are at a lethal angle of attack.
Last thing - mine had a little automatic flip up pitot cover. I've just taken it off and the airspeed over-read error has vanished.
I'm assuming turbulence from the ' flap' part was the problem.
Position error at high angles of attack is unknown, but assumed to be quite high, as per the translated pilots notes.
I came from the usual C172/ PA28 world and it's very different, there is a section of the flight envelope that you can get into that is simply not available to those aircraft.
It's a bit more like the energy management requirements of landing in gliders- sort of.
For what it's worth, it's 10 times more fun at half the price, but, it makes me sweat a bit sometimes. Usually going into a new strip on a cross-windy, bumpy day. But that's why we do it, isn't it?

[Flyin'Dutch']

The characteristics of the wing and having no flaps or airbrake can lead to an un-stalled but very rapid descent if speed decays below 40 knots indicated ( on mine). You need to have flared and be just above the grass by this time.
The actual stall I take to be just under 34 knots, as that is the indicated speed at the (just beginning) of lift off.

I think that explains your questions on the other thread.

Your stall speed is 40kts*.

That you can lift off at 34kts indicated is because the Jodel wing is very low over the ground and you are therefore having a lot of ground effect during the take off and the last stage of the landing.

If you fly your approaches at 43 kts you are too close to the stall to be safe.

*whether you get a classic nose drop etc on stalling or just a high sink rate will depend on aeroplane type, loading and pilot technique.