thomasjorgensen
Member
Will the upcoming EVO 2 retract be a taildragger?
Van's Air Force
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EVO 2
- Thread starter thomasjorgensen
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thomasjorgensen
Member
That is gonna be one pretty bird then! 
Doesn't that pose a challenge aerodynamically though as the wheels must retract into the leading half of the wing (easily disrupting the attached airflow)?
Does anyone think there will be considerable speed gains from sucking up the gear, or is it more of an aesthetics thing? (I suppose it all depends on how well the system is designed and built).
It will probably have a more noticeable effect than some of the RV RG conversions though!?
Doesn't that pose a challenge aerodynamically though as the wheels must retract into the leading half of the wing (easily disrupting the attached airflow)?
Does anyone think there will be considerable speed gains from sucking up the gear, or is it more of an aesthetics thing? (I suppose it all depends on how well the system is designed and built).
It will probably have a more noticeable effect than some of the RV RG conversions though!?
Christopher Murphy
Well Known Member
RG effect
I suspect retracting the gear will have a substantial effect considering the fixed gear airplanes are reaching 250mph+. At those speeds even a well faired fixed gear is creating substantial drag. Weight is the issue and it sounds like Mark is dealing with that too. I think you will be seeing performance approaching the sx-300 numbers. Alot depends on what airfoil sections are used too.
cm
I suspect retracting the gear will have a substantial effect considering the fixed gear airplanes are reaching 250mph+. At those speeds even a well faired fixed gear is creating substantial drag. Weight is the issue and it sounds like Mark is dealing with that too. I think you will be seeing performance approaching the sx-300 numbers. Alot depends on what airfoil sections are used too.
cm
thomasjorgensen
Member
Thanks Christopher.
Now it'll be interesting to see what the price will be!
Now it'll be interesting to see what the price will be!
StickandRudder
Member
If you are interested there is a discussion group with more info. Contact Mark to join. As has been said he is ready to produce, but needs more committments. It is going to be a nice airplane. Composite wings and control surfaces are going to make it a lighter plane too. Real excited to see this thing come out!
Bruce Russell
Well Known Member
Where is the discussion group hosted?
fl-mike
Well Known Member
It's a Google group.
[email protected]
[email protected]
I am not sure this is true, the fixed gear lancairs are not much slower than the retracts.
Rhino889
Well Known Member
I tried that and received a "not delivered" message?
Christopher Murphy
Well Known Member
performance
I would expect at least 270 or 280 mph or I couldn't see any reason for designing a new wing and RG.
It will be interesting to see how it performs.
CM
I would expect at least 270 or 280 mph or I couldn't see any reason for designing a new wing and RG.
It will be interesting to see how it performs.
CM
F1Boss
Well Known Member
Data?
Hey Danny:
I see a 25KTAS difference between the FG and the RG (TCM 550 equipped), found on the Legacy Builders' forum: ~215TAS (FG) vs ~240KTAS (RG) @ 16-17GPH @ 7500-8500MSL.
http://www.highrf.com/forums/viewtopic.php?f=19&t=278
If you look at my pic on the 'show us your Rocket panel' thread, you will see that my ship (FG, 550) will do 208KTAS on 10.5GPH @17500MSL. Looks like I'm gonna have to drop to 8500' to get the engine to swallow 16GPH for a sort-of apples/apples test? If I can get 215KTAS/182KIAS at the same altitude, that will tell the tale; memory (not so good) tells me this speed is reached at ~12GPH at that altitude? Caveat: a quick calc tells me this (16GPH) drops my range from 1000NM to 750 or so. OUCH!
I think a 25KTAS difference is worth the work associated with the RG system, but I am impressed that there is that much difference!
Cheers
Mark
Hey Danny:
I see a 25KTAS difference between the FG and the RG (TCM 550 equipped), found on the Legacy Builders' forum: ~215TAS (FG) vs ~240KTAS (RG) @ 16-17GPH @ 7500-8500MSL.
http://www.highrf.com/forums/viewtopic.php?f=19&t=278
If you look at my pic on the 'show us your Rocket panel' thread, you will see that my ship (FG, 550) will do 208KTAS on 10.5GPH @17500MSL. Looks like I'm gonna have to drop to 8500' to get the engine to swallow 16GPH for a sort-of apples/apples test? If I can get 215KTAS/182KIAS at the same altitude, that will tell the tale; memory (not so good) tells me this speed is reached at ~12GPH at that altitude? Caveat: a quick calc tells me this (16GPH) drops my range from 1000NM to 750 or so. OUCH!
I think a 25KTAS difference is worth the work associated with the RG system, but I am impressed that there is that much difference!
Cheers
Mark
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Toobuilder
Well Known Member
There are plenty of good reasons to build composite wings, but going for a lighter structure is not one of them. It is very tough to beat aluminum for weight.
There is NO WAY that adding retracts and composite wings is going to result in a lighter aircraft.
I too will be interested to see just how much performance the retracts add. Rockets are fast, but are still slow enough that retracts won't buy you a whole lot over a well done fixed gear. It's my suspicion that it will improve some, but would not be a favorable cost/benefit analysis. In the end, people will be attracted simply for the "cool" factor.
Michael White
Well Known Member
Toobuilder
Well Known Member
No, but it's certainly high on the list!
F1Boss
Well Known Member
Aw geez...
Hey Toobuilder:
The Evo wing set (just the wing, mind you) weighs ~85lbs MORE than the Sport wing set. I swear you could hang 250lb bombs + racks on it! Look up 'overbuilt' in the dictionary, and you'll see a photo of the Evo wing. Good thing the rest of the plane is better thought out, else we'd have a 1800lb EW.
The engineers tell me that the new wing will weigh about the same per SF as the sport wing (they have their formulas), so the ship loses 85lbs immediately. That alone ought to allow for retracts at no weight penalty. But, we get to toss out the Ti legs too, at ~34lbs, so now we have 119lbs to play with - to simply make it all equal. Heck, the engine mount also loses the leg sockets - another 5lbs.
So, "never say never" might apply here. It COULD BE be lighter!
Speed: if I can show the same speed as a Legacy FG in the current config, why should I not expect similar speed gains if I hide the legs as the Legacy RG does? Probably won't be that dramatic, as we are not using the 85SF wing as the Legacy does; ours will be ~92sf or so, to keep the stall/approach speeds down to manageable limits. Optional tip extensions can be fitted to bring the wing back up to 100sf, as might be required in Canada.
So, if we find +12-15KTAS over the Evo, would that be enough? What if it's more than that?
In any case, the whole project is market driven, and it is not gonna be cheap (the production numbers are too small). If enough folks agree that it's a good plan, we will get to make a few more airplanes. If not, well then, that WalMart greeter job might start looking better and better.
I, for one, would sure like to see one of these things in flight. It was in my original business plan in 1996. Other like-minded individuals just might agree, and step up, and then I'd have to prove my expectations are genuine. Well, OK by me!
So, are ya feelin' lucky? Well, are ya?
Carry on!
Mark
Hey Toobuilder:
The Evo wing set (just the wing, mind you) weighs ~85lbs MORE than the Sport wing set. I swear you could hang 250lb bombs + racks on it! Look up 'overbuilt' in the dictionary, and you'll see a photo of the Evo wing.
Good thing the rest of the plane is better thought out, else we'd have a 1800lb EW.The engineers tell me that the new wing will weigh about the same per SF as the sport wing (they have their formulas), so the ship loses 85lbs immediately. That alone ought to allow for retracts at no weight penalty. But, we get to toss out the Ti legs too, at ~34lbs, so now we have 119lbs to play with - to simply make it all equal. Heck, the engine mount also loses the leg sockets - another 5lbs.
So, "never say never" might apply here. It COULD BE be lighter!
Speed: if I can show the same speed as a Legacy FG in the current config, why should I not expect similar speed gains if I hide the legs as the Legacy RG does? Probably won't be that dramatic, as we are not using the 85SF wing as the Legacy does; ours will be ~92sf or so, to keep the stall/approach speeds down to manageable limits. Optional tip extensions can be fitted to bring the wing back up to 100sf, as might be required in Canada.
So, if we find +12-15KTAS over the Evo, would that be enough? What if it's more than that?
In any case, the whole project is market driven, and it is not gonna be cheap (the production numbers are too small). If enough folks agree that it's a good plan, we will get to make a few more airplanes. If not, well then, that WalMart greeter job might start looking better and better.
I, for one, would sure like to see one of these things in flight. It was in my original business plan in 1996. Other like-minded individuals just might agree, and step up, and then I'd have to prove my expectations are genuine. Well, OK by me!
So, are ya feelin' lucky? Well, are ya?
Carry on!
Mark
Toobuilder
Well Known Member
OK,
Let me revise my statement: For an aircraft of this size, given an optimized structure for each ? an aluminum wing is hard to beat for weight.
One other thing against the composite wing weight is that it will have a much thicker layup than required if only air and structure loads are considered ? you also have to build in ?extra? just to keep the hangar rash down. Built strictly for air loads, the composite wing would be like an eggshell and extremely vulnerable to point loads (like kids? fingers at airshows). Given a wing the size of the 787, this extra thickness is built in as a function of a large structure so there is no ?extra? penalty? However, with a wing the size of the Rocket, this extra weight is a big percentage of the total - and that hurts you.
Having said all that, I am in preliminary design of a Rocket class airplane and it will most likely have a composite wing. It?s the only way to get an accurate wing surface. I don?t doubt that your EVO 2 will perform better ? it really comes down to the trade study of the retract option. Is it enough bang for the buck?
Don?t take the above as criticism ? I?m a huge fan of the airplane! I wish I was in the position to buy one of the F1 kits back in the day. I?m very interested in your outcome and wish you the best of luck.
Let me revise my statement: For an aircraft of this size, given an optimized structure for each ? an aluminum wing is hard to beat for weight.
One other thing against the composite wing weight is that it will have a much thicker layup than required if only air and structure loads are considered ? you also have to build in ?extra? just to keep the hangar rash down. Built strictly for air loads, the composite wing would be like an eggshell and extremely vulnerable to point loads (like kids? fingers at airshows). Given a wing the size of the 787, this extra thickness is built in as a function of a large structure so there is no ?extra? penalty? However, with a wing the size of the Rocket, this extra weight is a big percentage of the total - and that hurts you.
Having said all that, I am in preliminary design of a Rocket class airplane and it will most likely have a composite wing. It?s the only way to get an accurate wing surface. I don?t doubt that your EVO 2 will perform better ? it really comes down to the trade study of the retract option. Is it enough bang for the buck?
Don?t take the above as criticism ? I?m a huge fan of the airplane! I wish I was in the position to buy one of the F1 kits back in the day. I?m very interested in your outcome and wish you the best of luck.
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