Quantum Leap test flight
- Thread starter wexfordair
- Start date
The underside vents are more tied into the ability to have winglets or not, and guaranteeing pitch stability by preventing undersurface blowdown at low angles of attack, I think... the end of the Quantum wing is open, with no option for winglets or tip fairings...
There's no point investing more development time and work on 15m^2 wing, it's too big for what the market wants.
For the fast cruiser that seems to be what people are after in 2 seaters, 12 to 13m^2 is the size that is going to be preferred. Look at BioniX 2, Exodus Delta Jet 2, etc...
That's the size of the GT450...
There's no point investing more development time and work on 15m^2 wing, it's too big for what the market wants.
For the fast cruiser that seems to be what people are after in 2 seaters, 12 to 13m^2 is the size that is going to be preferred. Look at BioniX 2, Exodus Delta Jet 2, etc...
That's the size of the GT450...
To gain a little more speed on a Quantum wing look at where the washout rods are situated regarding their markings, (each sides markings may not be the same and could have been previously altered to take out turns etc) if they are around the halfway mark you could de-tension the wing and drop them a couple of notches without any adverse effects on handling but possibly achieving around 5mph.
Also replace the bungees on the trailing edge and try to make the new bungee a little tighter, however there is a limit as to what you can gain as typically most wings of that age will have lost a significant amount of its taughtness.
Also replace the bungees on the trailing edge and try to make the new bungee a little tighter, however there is a limit as to what you can gain as typically most wings of that age will have lost a significant amount of its taughtness.
I assume you mean the tip adjusters as the washout rods are fixed with good reasons for pitch stability. You can rotate the tip adjusters without de-tensioning the wing, once you have slackened the Allen key, look for a hole in the plastic into with you can insert the long part of the tool and rotate the end of the leading edge which has the sail retainer going over it.
If this is any effect on handling it will be to make the wing wind into turns, most noticeable on climbing turns. This wouldn't bother a hang glider pilot, but might be disconcerting for a low airtime flexwing pilot with no experience elsewhere.
There's also a limit on this because tighter bungees adversely affect handling. Once the sail is bagged out on a flexwing, the only real way to restore the spanwise tension is by shimming at the end of the outer leading edge - this isn't an option with the Quantum. Some flexwings have spanwise adjusters at the tip to allow this to be set. New Quantum sails with the Technora trailing edge strip will be better at resisting stretch, as Technora is wickedly stable dimensionally, and it will lower the Betts test values for the main sail, but then adds the Brooks test which is another failure point. This lower stretch also affects trim speed, so a standard Quantum with a new sail may trim out faster anyway.
One of the ways the Leap achieves higher trim speed is because the wing keel has a new hole for the hang point added in front of the existing one, which is what the trimmer and large hidden bungee in the upright then act against to restore lower trim speeds. The Leap has a very different feel in pitch to a basic Quantum. Also, if the trimmer fails, there will be a fair amount of pushing out to do if you don't want to go home at close to 80mph. Worth keeping an eye on the trimmer cord where it exits the top of the upright... there might be a wear point there.
Stall characteristics have been altered as the lower rigging wires are different. It's harder to stall one up.
I've been lucky enough to get some flights on the Leap featured in the review...
If this is any effect on handling it will be to make the wing wind into turns, most noticeable on climbing turns. This wouldn't bother a hang glider pilot, but might be disconcerting for a low airtime flexwing pilot with no experience elsewhere.
There's also a limit on this because tighter bungees adversely affect handling. Once the sail is bagged out on a flexwing, the only real way to restore the spanwise tension is by shimming at the end of the outer leading edge - this isn't an option with the Quantum. Some flexwings have spanwise adjusters at the tip to allow this to be set. New Quantum sails with the Technora trailing edge strip will be better at resisting stretch, as Technora is wickedly stable dimensionally, and it will lower the Betts test values for the main sail, but then adds the Brooks test which is another failure point. This lower stretch also affects trim speed, so a standard Quantum with a new sail may trim out faster anyway.
One of the ways the Leap achieves higher trim speed is because the wing keel has a new hole for the hang point added in front of the existing one, which is what the trimmer and large hidden bungee in the upright then act against to restore lower trim speeds. The Leap has a very different feel in pitch to a basic Quantum. Also, if the trimmer fails, there will be a fair amount of pushing out to do if you don't want to go home at close to 80mph. Worth keeping an eye on the trimmer cord where it exits the top of the upright... there might be a wear point there.
Stall characteristics have been altered as the lower rigging wires are different. It's harder to stall one up.
I've been lucky enough to get some flights on the Leap featured in the review...
The wing of a Quantum is pretty tame even to a low hours P1, when pushed towards its envelope which actually takes some doing it still behaves nicely, the recommendations that I spoke about came from the guy at Rochdale who built the wings (I won't mention his name on the tinterweb) and tried and tested at our place.
You're right about altering the wing tips under tension but it sempt so much easier without tension and the difference that tighter bungees make is small but its helpful in cleaning up the trailing edge where no technora is present.
Moving the hangpoint could be done but best done on a jig and probably best done by someone with competence and there'd possibly be a mod involved.
As you say the only way to achieve a huge improvement is to go all the way with technora and hangpoint position etc but for the cost of new bungee and a tip adjustment might yield improvement.
There is also (for the older Quiks with manual trim) a new batten profile that can increase the wing speed, (again tried and tested), maybe worth enquiring if one exists for the Quantum.
You're right about altering the wing tips under tension but it sempt so much easier without tension and the difference that tighter bungees make is small but its helpful in cleaning up the trailing edge where no technora is present.
Moving the hangpoint could be done but best done on a jig and probably best done by someone with competence and there'd possibly be a mod involved.
As you say the only way to achieve a huge improvement is to go all the way with technora and hangpoint position etc but for the cost of new bungee and a tip adjustment might yield improvement.
There is also (for the older Quiks with manual trim) a new batten profile that can increase the wing speed, (again tried and tested), maybe worth enquiring if one exists for the Quantum.
Before I went SSDR with my trikes my old inspector told me anecdotally of a Pegasus Q (Q1 that is, not the Q2 wing as fitted to the Quantum) he knew of that could easily reach 100mph. I asked him how and he told me it was all to do with profile. He said he'd seen the aircraft and flown it himself for a check flight, so he could corroborate the figures. When I asked him what had been done to the profile to add so much extra speed he said it looked as though the owner had increased the curve of all the battens, so the wing appeared to have a much higher/deeper profile. How having a higher/deeper profile would give extra speed I've no idea.
As for me, after I SSDR'd all my planes I found that putting a Raven wing on my 462 powered Pegasus XL trike gave me 80mph cruising if I wanted it, and I once had the plane up to 95mph on the ASI, although at that speed there was some divergence in the wing. After that I increased the tension in the tip adjusters which rotated the tips upwards a little. This slowed the wing a bit, but made it much more comfortable to fly at 60-70mph.
As for me, after I SSDR'd all my planes I found that putting a Raven wing on my 462 powered Pegasus XL trike gave me 80mph cruising if I wanted it, and I once had the plane up to 95mph on the ASI, although at that speed there was some divergence in the wing. After that I increased the tension in the tip adjusters which rotated the tips upwards a little. This slowed the wing a bit, but made it much more comfortable to fly at 60-70mph.
Hi Dave, you're 100% correct in this being a mod, and quite an involved one as you would need to have the trimmer to make the aircraft nice to fly at lower speeds, and for take off and landing. The Quanttum has had three possible positions for the hang point during its life, this forward one for Leap mods, the standard one and one hole added rearwards for aerotow.
There is an altered batten profile for the Quantum to go faster. It wasn't implemented on the Leap I flew. I'd be wary because the Leap also has an additional strap on the innermost battens to maintain their position relative to the keel. I haven't worked out why this is yet. It is one of the Leap mods, but I don't know if it can be done alone or needs some other mods already in place. It's worth knowing that some Leap mods do require other ones to already be in place.
There is a mod to the Q battens for profile to cure yawing...
One of the areas of Section S that leaves a bit to be desired in is pitch stability. As a fair few hang glider pilots have died from lack of the same, HG airworthiness concentrates much more on this. Yes, microlights benefit much more from pendulum stability, but once tumbled there is not the same level of reserve carrying that HG pilots tend to do, so more likely to be fatal.
When I was BHPA Airworthiness Co-ordinator a while back one of my incidents to investigate involved a HG pilot who had done just this, adjusting the batten profile away from the test rig certified one to achieve more speed and glide. As the first attempt rewarded, he pursued it further, until one thermal flying day he found himself sat on the sail of his inverted glider and had to deploy his reserve.
One of my first free flying Mentors died in a dive into hard ground in the Thames Valley in the early 1990s. The rebuilt, retested glider wasn't pitch stable, and had been released into the market after incorrect in house pitch testing. They were all recalled and had a fair few mods...
Divergence at speed is highly dangerous.
Your description is of a wing that's got marginal pitch stability at best, and whilst divergence may be obvious, the lack of pitch stability at low speeds is not, and will result in a tumble without warning in very rough air. All HG pitch accidents post certification schemes have been low speed tumbles...
Do you feel lucky?
There is an altered batten profile for the Quantum to go faster. It wasn't implemented on the Leap I flew. I'd be wary because the Leap also has an additional strap on the innermost battens to maintain their position relative to the keel. I haven't worked out why this is yet. It is one of the Leap mods, but I don't know if it can be done alone or needs some other mods already in place. It's worth knowing that some Leap mods do require other ones to already be in place.
There is a mod to the Q battens for profile to cure yawing...
One of the areas of Section S that leaves a bit to be desired in is pitch stability. As a fair few hang glider pilots have died from lack of the same, HG airworthiness concentrates much more on this. Yes, microlights benefit much more from pendulum stability, but once tumbled there is not the same level of reserve carrying that HG pilots tend to do, so more likely to be fatal.
When I was BHPA Airworthiness Co-ordinator a while back one of my incidents to investigate involved a HG pilot who had done just this, adjusting the batten profile away from the test rig certified one to achieve more speed and glide. As the first attempt rewarded, he pursued it further, until one thermal flying day he found himself sat on the sail of his inverted glider and had to deploy his reserve.
One of my first free flying Mentors died in a dive into hard ground in the Thames Valley in the early 1990s. The rebuilt, retested glider wasn't pitch stable, and had been released into the market after incorrect in house pitch testing. They were all recalled and had a fair few mods...
Divergence at speed is highly dangerous.
Your description is of a wing that's got marginal pitch stability at best, and whilst divergence may be obvious, the lack of pitch stability at low speeds is not, and will result in a tumble without warning in very rough air. All HG pitch accidents post certification schemes have been low speed tumbles...
Do you feel lucky?
On raven divergence; on my one I assembled the wing after a major strip down and rebuild to have the tip struts at what I thought was good and tight and went for a flight, the bar would move towards me, settle for a moment, and then come towards me again. It would keep doing this at all power settings. After lots of consultation with Chris I tightened the tips to near break point and suddenly it was perfect again! At this point I learned a lot of stuff from Chris about raven tuning, the trick to get high speed was to drop the tips and put more camber into the inner battens and it would easily break 100mph. It was the first to break 100 from what I was told, and that was with a 447. The caa got such a shock seemingly they demanded it be slowed down before approval!
I asked the bloke who designed the wing (I can't remember his name offhand) about that and he told me the turbulators on the upper surface near the wing tips are there for that very purpose, to provide the pitch stability that would be missing otherwise. He said that without the turbulators the cord at the wingtips would have to be double what it was.
Personally I never found the Raven wing to be unstable. In fact I preferred it to the Q wing, as it was better damped and had a greater speed range, and I never noticed any difference in stall characteristics even though I was told by my inspector that when the Raven wing stalls, it bites, whereas the Q wing just mushes and never really stalls at all.
Personally I never found the Raven wing to be unstable. In fact I preferred it to the Q wing, as it was better damped and had a greater speed range, and I never noticed any difference in stall characteristics even though I was told by my inspector that when the Raven wing stalls, it bites, whereas the Q wing just mushes and never really stalls at all.
That's the one. I knew it was double-barrelled, but lately I find I can't remember names.
In case you're wondering how I managed to ask him about the wing when he lives on a farm in the middle of nowhere in the US somewhere? I emailed him and we ended up having an interesting conversation. Later on he upset Big John Moore by not paying him the £25 John spent out on a book for him.
In case you're wondering how I managed to ask him about the wing when he lives on a farm in the middle of nowhere in the US somewhere? I emailed him and we ended up having an interesting conversation. Later on he upset Big John Moore by not paying him the £25 John spent out on a book for him.