Talk:SUMPAC

Another source
Lots of information here, probably not a reliable source for wiki purposes but I don't think he's making it up!! Nimbus (Cumulus nimbus floats by)    00:23, 14 August 2010 (UTC)


 * It is WP:SPS but I think it looks reliable enough to declare him an expert on the subject. - Ahunt (talk) 01:40, 14 August 2010 (UTC)


 * I would think so. Nimbus (Cumulus nimbus floats by)    10:17, 14 August 2010 (UTC)

Dear authors,

the third line and the figth line of the chapter "Performance" should be compared. This comparison gives reason for two remarks, the first one confirming (but explaining more in detail what is obviously meant) the given data and the second one correcting an obviously wrongly cited unit.

1.) It might be a bit unclear, was is meant with "Lift-to-drag" because this expression might refer to the overall airplane - but then it should be absolutely identical to the "maximum glide ratio" -  or solely to the wing. The lift-to drag-ratio of the wing solely calculated from airfoil data is always a bit better than the lift-to-drag-ratio of the whole airplane because the drag of the fuselage and the tail unit is added without further lift.

Thus, if the given lift-to-drag data of "36" refers to the wing only, this does not conflict with a maximum glide ratio data of "34".

2.) But the speed (105 km/h) where said maximum glide ratio is told to has been reached is obviuously wrong. The correct speed data must be very close to the speed told for the best lift-to-drag-ratio, namely 32 km/h. As one "foot" is defined as 12 inches, thus 12 x 2,54 cm, it calculates to 30,48 cm = 0,3048 m. Apparently not 105 km/h is meant (what would refer to a current competion sailplane) but 105 kilofeet/h, what is the same as 32,004 km/h -  and credible. Furthermore, this reported human powered plane would never reach at a speed of 105 km/h, not only because the power of a human being would be insufficient but even more because the never exceed speed  - please have a look at the first line of the chapter "Performance" -  is 33 km/h.

However, great thanks to the author who has reported about this admirable plane, its constructors and its pilot.

Kind regards

Klaus Kleinhoff — Preceding unsigned comment added by 217.111.75.13 (talk) 08:39, 30 October 2013 (UTC)

airfoil definition incorrect?
The airfoil is listed as NACA 65a 818, but the linked airfoil page considers that invalid.

It may well be the airfoil page that is wrong; at this point I'm only noting the inconsistency.

According to the airfoil page, series 6 NACA airfoils should look like

NACA 612-315 a=0.5

but the a can be left out and defaulted to 1. I suppose the intended airfoil may have been 651-818 a=1 but that is enough of a change that I don't want to just guess.

JimJJewett (talk) 20:44, 1 January 2021 (UTC)


 * Yes, it was incorrect, apologies for that. The source page numbers were also incorrect, this information was added by an editor who is currently blocked for problematic editing. The source states that it is a 12% Wortmann section (Franz Xaver Wortmann) changing to a NACA section at the tip. I can see that this has caused questions on other forums/aviation websites, Wikipedia states that it should not be used as a citable source (errors like this are one reason). if an article has Featured Article status then the information is mostly correct as it will have been checked by multiple editors during the review process and then closely monitored for thereafter. Thanks for highlighting the problem. Nimbus (Cumulus nimbus floats by)  11:34, 2 January 2021 (UTC)


 * On further checking the source I had myself erroneously entered the airfoil given for the HMPAC Puffin, I can confirm that the NACA airfoil listed is what the source says but the page number was incorrect. Nimbus (Cumulus nimbus floats by)  13:27, 2 January 2021 (UTC)