Thorp Air Command - T18.net

New Mosaic rules out. Am I reading it correctly? Is the T18 still outside of the sport pilot capabilities due only to stall speeds? You can fly complex with endorsements but a fixed pitch non-retractable t18 is still out because of 4-5 kts in stall….

BADA BING , BADA BOOM ! Document is 318 pages long ! Can Mr. Wizard please decode it in plane (LOL) language !!

RB
NX115RX

Is it possible to originally in newly competed aircraft to install VG’s and possibly record the flaps up stall speed in the original test hours. Perhaps it would lower the “clean” stall speed to be below the mosaic speed. Then after a while the VG’s just happen to fall off.

Would that then meet the mosaic rules? Or by removing VG’s would that require an new test phase to be required?

I know Vag’s would NOT help landing as the AOA at touchdown would hit twilnforst and be a mess. So it would not reduce landing speed or attitude. But it might allow the T18!” To meet the mosaic rule.

Just asking the question.

So what is the consensus on clean stall speed for traditional original thorp wing? And for a Suderland airfoil or S-18 wing?

I suspect the new mosaic rules the Vans RV series of Two seat aircraft will comply with its slightly thicker wing. But who in the FAA would even suspect of an RV6 or RV7 complies would even think twice about a thorp not qualifying??

Also reading what I have so far of the NRPMnon mosaic. The 54 kt CAS clean stall speed was established such that it would naturally result in all the aircraft to be limited to MTOWnof about 3,000 lbs.

Seems odd that the gas claimes the wanted to eliminate weight restriction. But then in the preamble states that the Vs1 stall of 54 kts limits the weight to about 3,000 lbs.

I argue that the clean stall speed is relatively irrelevant for safety. As most stall spin accidents do not happen I clean configuration. Thus Vso. Stall in the landing configuration would be more appropriate.

Also the mosaic rules I believe allows night flight with sport pilot certificate. But requires medical certificate. Why? Or at least I have not read far enough to determine if that means 3rd class or if “basic med” is all that it requires.

Also mosaic seems to be very concerned with the sport pilot not have priceless that exceed recreational pilot certificate. When in reality what should be done is to reduce the requirements of recreational and have eliminated sport pilot. Or simply kept sport pilot to be “heavy” and two seat ultralights.

These new sport pilot rules are essentially 90% of recreational. So this proposal should have in my opinion be set out to allow existing sport pilots to have a transition for additional training to obtain the recreational. And recreational pilots to have new conditions.

I see almost zero difference between sport and recreational at faith these proposed changes.

The faa has 90 days for public to comment. I think we all ought to consider submitting our comments.

Be aware they will only consider the proposal and simply saying replacement as I stated above will be ignored.

I suggest perhaps comment that the clean stall speed seem irrelevant. And perhaps the same speed for stall speed in the landing configuration should be used instead. And being selfish. This speed ought to be set to include all Thorps!!

Just some of my additional banter.

I welcome others perspectives.

all this being said. Perhaps except night flight. A basic med even with higher clean stall speed will allow Thorpe to be flown within this new rule. Day and IFR with rating and endorsements.

My POH list the clean stall, with the original airfoil, as 62 MPH = 53.9 KTS. I have not verified this speed.

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

I had been wondering if the Thorp would be allowed to operate under the new rules. It's so close in performance to what they are proposing that it would be a shame if it wasn't allowed. Fingers crossed I suppose. I agree with others that they should consider landing configuration rather than clean stall speed.

what sort of bothers me is that in the preamble, the FAA states that they want to do away with a max weight limit. And technically they do, as the proposed rule does not specify a max weight.

HOWEVER, they then go on to state that the VSO in clean configuration indirectly results in a max of around or about 3,000 lbs. So it APPEARS that they set the VSO to get an aircraft about max weight of 3,000 lbs.

The problem is, that something like Thorp is SO far away from that weight limit, but yet the clean stall speed is bumping right up to the this limiting max speed for the new rule.

Actually the term clean stall speed is not totally correct. As the proposed new rule allows for retract. The VSO is I believe defined as stall speed without deploying any lift enhancement device. I am not sure that extending retract gear adds much if any lift. But if it does, it adds way more drag than lift. since most T/S-18's do not have retract this is moot point. but thought I'd add that in.

If they were to use stall in landing configuration, they may lower it to still keep out some aircraft possibly including the Thorp.

I guess what my premise is, if they determined the VSO speed to dictate a undisclosed weight limit. Then why should much lighter aircraft be subject to this stall speed limitation.

Also it is Calibrated Air speed. Who even remembers how to obtain CAS? I sure don't. I know it is supposed to correct of position and interment error. But how do we get this number anyhow? How can existing aircraft determine the CAS if it is not specifically tested or listed in the POH?

I still have to question the reality of who would actually call on the carpet any thorp owner to prove that their individual aircraft as a flaps up CAS that is 54 knts or less? Especially if every RV6 or RV7 meets this limit. Heck 99% of the FAA ramp checkers would not know that a thorp is not an RV. So what are the chances this ever becomes an issue in real life?

The NRPM made several notes that they put a cap on the performance and other pilot privileges to not exceed the next higher certificate. That being "recreational" pilot certificate. When in reality what should have really been done is to remove light sport OR recreational and allowed time for transition from one or the other. After all how many recreational pilot certificates are held? This new light sport rule and privileges is like 98% of the recreational already. So what are they really accomplishing by having two nearly identical certificate levels?

This whole rule is very confusing, such as night flight. It is possible with endorsement, but to fly at night you still need a 3rd class medical OR a drivers license if in light sport aircraft. They make no mention of "basic med", which is less than 3rd class but more than a drivers license. Maybe for those who have a basic med, as long as they have a drivers license it is moot. But the rule would be more clear if it stated basic med.

Have any of you responded to the extended NPRM (22 Jan 2024)? If not, here is a good link to the EAA website for a Guide to Drafting MOSAIC NPRM Comments.

https://www.eaa.org/eaa/news-and-publications/eaa-news-and-aviation-news/news/mosaic-commenting-guide

There is some good suggestions in this guide to support the raising of the Vs1 stall speed from 54kts to 57kts and increasing the MTOW.

Still time . . . .

Rob

AOPA/FAA/NBAA/NATA response to FAA notice of proposed rulemaking (22 Jan 2024)

https://download.aopa.org/advocacy/2023/FAA_2023_1377_1244_attachment_1.pdf?_gl=1*nc8sf4*_gcl_au*NjEzODcyNDQ1LjE3MDcwNjY3OTE.*_ga*MTExNzk2NDE4OC4xNzA3MDY2Nzkx*_ga_B4TCX358SE*MTcwNzA2Njc5MS4xLjEuMTcwNzA2Njg3MC42MC4wLjA.*_ga_SM42H3BVW5*MTcwNzA2Njc5MS4xLjEuMTcwNzA2Njg3MC42MC4wLjA.&_ga=2.116274959.887273194.1707066792-1117964188.1707066791