Given the LSA rewrite could it be possible an RV8 could be operated as LSA? Would be a nice option to have, maybe benefit those dealing with medical issues or those only wanting LSA ticket. I assume airworthiness requirements of a new aircraft would not change. It seems -8 is not to far outside current LSA requirement so if the LSA expands it should catch the -8 !
Van's Air Force
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RV-8 possibility falling into new LSA category?
- Thread starter BMallory
- Start date
What’s the clean stall speed of an RV8?
That’s the thing that’s going to keep a lot of airplanes out of LSA. People talk about how the proposed MOSAIC rule supports an increased stall speed, but it’s Vs1 — clean stall — not Vso; it’s set at 54 knots. It’s too bad, really. It means that you can’t meet the requirement with fancy lift enhancing devices or even good flaps.
That’s the thing that’s going to keep a lot of airplanes out of LSA. People talk about how the proposed MOSAIC rule supports an increased stall speed, but it’s Vs1 — clean stall — not Vso; it’s set at 54 knots. It’s too bad, really. It means that you can’t meet the requirement with fancy lift enhancing devices or even good flaps.
According to Vans website, the stall speed for the RV8 is 58 mph. Is this still true? 54kt is 62mph
I asked the local pilots who test flew their new RV8 but none of them quoted the hard VS1 numbers for theirs. I know one who flew his RV8 but did not really "test" anything other than the top speed.
I asked the local pilots who test flew their new RV8 but none of them quoted the hard VS1 numbers for theirs. I know one who flew his RV8 but did not really "test" anything other than the top speed.
Attachments
2theskyy
Well Known Member
4. Maximum Stalling Speed (VS1)
The light-sport aircraft definition in § 1.1 limits the maximum VS1 for light-sport aircraft to 45 knots CAS at the aircraft's maximum certificated takeoff weight and most critical center of gravity. The proposal would retain the 45 knots CAS maximum VS1 for gliders and weight-shift-control aircraft. The FAA is proposing to increase the maximum VS1 to 54 knots CAS for airplanes.
Sorry, I’m late to the party.
The light-sport aircraft definition in § 1.1 limits the maximum VS1 for light-sport aircraft to 45 knots CAS at the aircraft's maximum certificated takeoff weight and most critical center of gravity. The proposal would retain the 45 knots CAS maximum VS1 for gliders and weight-shift-control aircraft. The FAA is proposing to increase the maximum VS1 to 54 knots CAS for airplanes.
Sorry, I’m late to the party.
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Vans published stall speed is VS0 (Landing configuration, i.e. full flaps). The LSA stall speed is VS1 (Clean, i.e. flaps up).
Vans does not publish VS1 speeds.
Agree. I think this will be a mess as written. For experimental even vs0 is established during flight testing so the Vans number is just a design goal. Some people might have established vs1 and market it on their instrument or manual. Some might not have. In either case the speeds are close enough that some RV-8 might be LSA others might not…. .
Oliver
With the new NPRM if the RV-8 met the vs1 stall speed, it could be flown by a Sport Pilot, i.e. without a medical.
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Van could be building them as factory made LSAs for one ( last time iI heard they are lobbying to change the new LSA stall speed limit of 54 to VSO)
https://youtube.com/watch?v=9zf4-zQcPfg&feature=sharec
RV8JD
Well Known Member
Several years ago I communicated with Van’s about the published max gross weight (1800 pounds) stall speeds of the RV-8 when I was looking at its maneuvering speed.
Van’s verified that the RV-8's flaps down stall speed (Vso) is approximately 58 MIAS/50.4 KIAS, as shown on the RV-8's performance page.
They also verified that the flaps up, clean stall speed (Vs1) is approximately 64 MIAS/55.6 KIAS, which is shown on their “Airspeed Indicator Markings by Model” chart as the bottom of the green arc.
But again, those are Indicated Airspeed and the new MOSAIC NPRM stall speed requirement is stated in Calibrated Airspeed (Vs1=62 MCAS/54 KCAS). So the instrument and position error at those low speeds needs to be measured to find out what the RV-8's stall speeds are in CAS for a valid comparison.
Van’s verified that the RV-8's flaps down stall speed (Vso) is approximately 58 MIAS/50.4 KIAS, as shown on the RV-8's performance page.
They also verified that the flaps up, clean stall speed (Vs1) is approximately 64 MIAS/55.6 KIAS, which is shown on their “Airspeed Indicator Markings by Model” chart as the bottom of the green arc.
But again, those are Indicated Airspeed and the new MOSAIC NPRM stall speed requirement is stated in Calibrated Airspeed (Vs1=62 MCAS/54 KCAS). So the instrument and position error at those low speeds needs to be measured to find out what the RV-8's stall speeds are in CAS for a valid comparison.
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dmattmul
Well Known Member
Vans LSA models, including 15
I'm pretty sure I heard Ryan make the comment at OSH all models except the 10 and 14 would meet the new rules as currently being proposed. The group is still wanting to alter the stall configuration wording.
After looking at some Vso data possibly I did not hear him correctly.
I'm pretty sure I heard Ryan make the comment at OSH all models except the 10 and 14 would meet the new rules as currently being proposed. The group is still wanting to alter the stall configuration wording.
After looking at some Vso data possibly I did not hear him correctly.
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As Van's numbers are interesting as a general reference they really have little bearing to what the VS0 and VS1 speeds of any particular RV-8 are.
As far as I know one guy might have rigged his flaps negative and another might have a STOL kits installed. So EVERY experimental aircraft has its own VS0 and VS1 of which only VS0 is required to be documented in the log book at end of phase 1. There is just no easy way of telling which RV-8 will be LSA and which won't considering how close the numbers are ... . As said mess... .
Oliver
One might have to add another foot to each wing for the few models that might be too fast as is...
David Paule
Well Known Member
That has strength, stability and flutter issues and is not recommended for a builder who is not properly educated in those areas. Even so, someone who is might decide that it would be prudent to avoid that approach.
It would be easier, since the builder can set the gross weight, to set an appropriate lighter weight and build it light enough to still be useful.
Dave
It would be easier, since the builder can set the gross weight, to set an appropriate lighter weight and build it light enough to still be useful.
Dave
RV8JD
Well Known Member
Effect of VG's on the RV-8
Nigel Speedy did some extensive flight testing on his RV-8 to identify the effect of VG's on several different performance parameters. One thing he did not test was the chordwise location of the VG's.
On his RV-8 the wing VG's reduced the cruise speed by approximately 4 KTAS (The table below shows 5 KTAS, but 1 KTAS was due to the VG's installed on the underside of the horizontal stab).
Note that the stall speeds were unchanged.
KitPlanes article--> https://www.kitplanes.com/vortex-generators-on-an-rv-8/
Nigel Speedy did some extensive flight testing on his RV-8 to identify the effect of VG's on several different performance parameters. One thing he did not test was the chordwise location of the VG's.
On his RV-8 the wing VG's reduced the cruise speed by approximately 4 KTAS (The table below shows 5 KTAS, but 1 KTAS was due to the VG's installed on the underside of the horizontal stab).
Note that the stall speeds were unchanged.
KitPlanes article--> https://www.kitplanes.com/vortex-generators-on-an-rv-8/
I’d bet there isn’t an RV flying whose owner or pilot knows what his calibrated airspeed is, especially at low speeds. I don’t think there’s a way to measure it without expensive instrumentation.
But I’ll also bet, if a Vs1 of 54 knots is the only thing standing between an RV and LSA status, a lot of manuals are going to get addenda noting a Vs1 of 54 knots. And, honestly, if it’s only a couple of knots, who’s it going to hurt?
But I’ll also bet, if a Vs1 of 54 knots is the only thing standing between an RV and LSA status, a lot of manuals are going to get addenda noting a Vs1 of 54 knots. And, honestly, if it’s only a couple of knots, who’s it going to hurt?
MacCool
Well Known Member
I would think insurance would be more likely underwritten based on the highest certificate of the pilot rather than the rules the airplane was being flown under. That seems like it would be the more relevant variable.
I have also mentioned this challenge. I am thinking that we as a group need to use this to our advantage during the public comment period. The op lims are boilerplate, so pretty much NO EAB planes have a formal Vs1, though I am sure most may test for one to properly mark their ASI. I have heard that close to 20% of the GA fleet is now EAB and growing every day. We need to push the FAA to recognize this error in their approach. Our comments should also indicate that the number chosen in the proposal is right in the middle of a VERY large aircraft population and that moving the proposed number from Vs1 to Vs0 would add A LOT of very safe and easy to fly airplanes. We should also add that this would not create a fundamental risk to their approach. Flaps fail and any pilot MUST be able to safely land the plane without flaps. The FAA knows this and is why they make us prove that ability in our PPL checkride. Therefore, the proposed change should not have a safety impact.
Larry
Several ways to skin that. It is not very hard to make your ASI read low. There is no calibrated airspeed in an EAB, as those speeds are tested and therefore set via whatever instrument is installed by the builder and it is almost never a sophisticated boom system like the big boys use. Vs1 for any given EAB plane is whatever the builder puts in the logbook and that includes instrument error as well as operator error.
MacCool
Well Known Member
If you have a PP certificate but you don't have a current medical or Basic Med, could you fly an LSA with just your drivers license?
I guess you could, but the question is why? Is a medical or Basic Med inconvenient/costly, or are you not able to attain that standard?
If it is a matter of convenience/cost, then great you saved $150 and an hour going to the AME or your Family Doc. If you're not fit, I can't see how its ok. I think people have a misunderstanding that you get away with adverse medical conditions by avoiding an FAA medical or Basic Med and using your drivers license instead.
I presume that DQ type conditions that prevent you from FAA medical or Basic Med are directly related to safe operation of the aircraft. If you have one are you safe? That said here's the sport pilot reg about medical...
61.303 (b)(4) Not know or have reason to know of any medical condition that would make that person unable to operate a light-sport aircraft in a safe manner.
I get the feeling that people with DQ conditions don't apply to medicals/basic med in order not to fail. That means you KNOW. How do you use that driver license per 61.303 now?
I think there's an abundance of LSA pilots that fall into this category because they stop reading the reg right after they see driver license.
I think inviting this group to fast aircraft is a huge mistake.
MacCool
Well Known Member
I guess I could speculate a variety of scenarios, but the reason doesn't matter. I actually have both a Class 3 and Basic Med (until the Class 3 expires)...it was a stand-alone question borne solely of curiosity.
MacCool
Well Known Member
No apology necessary, no offense taken. I'm wading my way through the whole MOSAIC NPRM thing in case there something there my RV-9A and I would want to know now or in the future...
Ignoring pilot qualifications for a second, if there's a world in which one can build an LSA RV-X, there's no requirement that it follow the 51% rule. Yes, it must follow the factory recipe to the letter but after it's certificated as an E-LSA changes are allowed. Additionally, if one were to purchase a flying E-LSA instead of an E-AB, you could attend a class to be able to do your own conditional inspection even though you aren't the original builder.
There is hardly any difference between SP and PP training - nobody finishes SP at 20 hours and the actual difference is literally a few more hours at night + slightly longer cross country - regardless of the certificate people either get relatively comfortable flying/landing in about 20-30 hours or they don’t and struggle for 70 , 100 or just give up…
Ultimately , both end up just as green after getting the certificate and the real difference comes to play if and when PPs go on to get their commercial and specially instrument ..
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I like that the feds are contemplating loosening the reins slightly - that appeals to me. That is one of the main reasons I am building experimental. I can't say that staying current on medical or any of the other points raised are good or bad for everyone. I will say it is nice to see a slight trend out of FAA to let us use our judgment. It will be interesting to see where this goes or doesn't go
Majorpayne317641
Well Known Member
I was at a Fast safety meeting with FAA ops and airframe guys doing a presentation. They said the LSA category change will not change the original AW of any aircraft already built. However, if the aircraft qualifies as an LSA based on the performance parameters set by the LSA category, then the pilot may be a sport/LSA pilot flying it under that category. That’s what they said will be coming out soon/or has already come out.
MacCool
Well Known Member
The context was more about increasing privileges (altitude) and eliminating medical oversight to know if that sport pilot's physiology was compatible with his/her new flying privileges. It wasn't about the flying-the-airplane part.
That's the part I was wondering about. My Class 3 expires in 6 months and my Basic Med in 4 years. Nice to have other options for flying my E-AB beyond that. ("IMSAFE" notwithstanding).
I think there are more than a few DQ conditions from the FAA that both the Dr and the pilot would say DO NOT affect safe operation and therefore a benefit to BM or DL. A good example is having a stent put in to open a blocked atery. FAA says "No sir. Need an SI." Doc says :you are great; way better than before, when you were approved by the FAA" I used this example, as it is a benifit to the DL approach, as BM would still require a one time SI. There seem to be a lot of heart conditions, that when treated, the Dr gives the all good signal, but the FAA wants annual SI that cost thousands or dollar and take 3 months to get each year.
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