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REAL PERFORMANCE FOR THE RV-7

R

rvnor

Member
I'm planning too build one and how is the performance for the RV7???
207mph at 8000ft ~ 182 kts at 8000ft according too Van's.
This is true airspeed and indicated app. 160 kts???
What is the performance at sealevel ? 160-170 kts IAS at 75% with IO390 engnie 210hp+??? Fuelburn??
What is the VNE?
Is it possible to make a larger fuel tank?? 50 gallon...
Is this really the aircraft to build instead of the Glassair, Lancair etc...
Thanks
 
If you build according to Vans, the figures stated by Vans are true and correct.
If its the right plane for you?, only you can decide.
Good luck in your quest.
 
Outboard fuel tanks

Yes there have been a number of airplanes built with this mod.

Some use aftermarket tip tanks abut others have built an extra tank in the outboard protion of the wing. Its more work of course but quite feasable.

Having found a number of occasions when i could have used an extra 30 gallons I wish I had.

Frank
 
Finished mine in November. 180+hp C/S prop. 8000' 23" 2550 208mph 11GPH. More realistic cruise is 10,000' 21" 2350 190mph 8.2 gph LOP. Don
 
I have fitted tip tanks to my RV7. It gives me an extra 22.2 us gallons. I used the original Vans tips laid a foam sandwich with carbon cloth on the inside and carbon foam transverse ribs and closed out with a carbon rib on the inside face. The original tips will certainly split with 1.5 psi pitot pressure hence the strengthening. The tanks gravity feed into the mains via a non return valve simple and straight forward but I reckon it added around 150 hours work. You need to be aware not to exceed the MTOW as well. It does however give me nearly 6 hours at 178 ktas which at least gives me the opportunity to buy some duty free fuel!! 100 LL in UK is now 13.15 USD a gallon . I may even use the range to emigrate to the US!!
;) Steve
 
Leading edge fuel tanks

50 gallons!. What about an extra 38.5 gallons ?

I have had an engineer design leading edge tanks for the 7 and 8. All load testing exceeded our original specs. We loaded the tanks to 7.7 G's with no deformation, we then tested for a 9 G impact which resulted in a very small leak at one joint. One thing to note when adding so much weight is the undercarriage was never designed for such loads. When we conducted a load test on the undercarriage of the 7A it was found to be marginal even without extra fuel. I Recommended you do not land full of fuel in long range tanks !! Some times you have no choice..

I am not aware if any load testing has been done on these tip tanks. The problem that was pointed out to me is 1: The attachment at the tip is inadequate for such loads, and there would likely be little warning of any failure of this attachment. 2: Having such weight at the tip will increase the chance of a spin and increase the time required to regain control. Not a good combination on final. 3: If during turbulence the wing begins oscillating the extra fuel at the tip will increase the chances of structural failure. The wings on the rv's is very strong and its doubtful this would ever happen but you don't want to find out the hard way.

By having the fuel further inboard you decrease the chances of these problems due simply to the attachment method to the wing and the weight is distributed along the wing spar and not at its end.

Mick
 
Extra fuel and the performance

Hi Mick.
What do you mean with the extra 38,5 gallons? An inboard tank or extra leading edge tanks next to the ordinary tanks?
Any descriptions or/and pics?

Anyone else with descriptions/pics for xtra leadingedge tanks who works well?

The decision is made a long time ago and i'm planning to build the RV7 but i would like to have larger fuel capacity for longer flights.
What does Van's say to this?

Was my calculations correct for cruise speed, IAS at ground level???
App 170 kts at 75% with IO390 210 hp
Thanks
 
tip tanks

Wow, It's amazing see the locations of the responders on this thread. I guess we've got EMEA covered.

Here's an add-on tank kit sold through safeair. I can vouch that I'm happy with other stuff I've purchased from them...
http://www.safeair1.com/HWA/er_RV6.htm

I'm not installing tip tanks, at least from the start. I think I'd need a personal long range bio tank to take advantage of an extra fuel tank. If you went with fuel injection and electronic ignition, the possibilities for more efficient fuel burn might also be a good way to add range.

good luck.

Don
 
rvnor said:
The decision is made a long time ago and i'm planning to build the RV7 but i would like to have larger fuel capacity for longer flights.
What does Van's say to this?
Click to expand...
This thing is clear: they say No. They have never tested and not going to test those extended range fuel tanks available so they wash their hands off them. You are doing it by your own. There were good article about them in the RVator some time ago -- I don' t have mine RVators here so can't check which issue it was. Someone help with this?

But we are experimentalist so experimenting with them ain't bad thing. Just don't push limits too far: flutter, stability, CG, overload of other structures etc. And usually the lighter plane flies better.
 
In answer to the tip tank stress question, a full finite element analysis was carried out by the same company that provide such information to Airbus and the tip tanks and screw mounting system I described meet the standard JAR criteria ie an unplanned 9G impact. I do have reservations about the gear as well, hence my point about monitoring the 1800lb recommended MTOW and I have set myself a MLW of 1750lbs except in emergencies and in every event I use my well calibrated ACS AOA to ensure a min speed min ROD arrival.

The non return valve is an Andair product bulkhead mounting CK375 I think, in any event Andy Phillips at Andair will help (best to telephone) I also think Aircraft Spruce sell them. You will also need to modify the vent system to create a higher head and I would recommend specifying your check valve to be made with a tiny bleed so that when the main is filled to capacity via the gravity feeding tip tank you dont empty it out through the main vent. There are a number of other little things to do. I can tell you about them if you choose to proceed. Oh and if the main is full via the tips dont open the main tank fuel cap unless you want to see a blue geyser.

I have only fitted this system for as part of a long distance record breaking suite ( I still have to fit a 60 gallon tank in the right seat and footwell) You have to give some thought to the whole process before proceeding not least the potential performance and structural penalties that can occur. I have thought long and hard as to why I need 12.5 hours endurance. The aircraft can do it but she loses a little of her heart and soul if you know what I mean and as soon as I have done what I need to do the 60 gallon Fuselage tank is out and in the future when I am touring I will do it at the lightest fuel load that is safe for the journey. I have flown an RV6 with a little over 100 gallons on board and while it flew okay it bore little resemblance to the RV6 that we all know and love. Perfectly flyable but you need concentration rather than pure joy to fly if you get what I mean.

Happiness is a lightweight RV,it may be worth considering a nicely tuned 180 hp (Barrett) Lycoming (from memory about 20lbs lighter than a counterweight engine) with a well set up engine monitoring system lots of gap sealing and a stringent minimalist approach to weight. I think 180KTAS would be entirely possible for nearly 4 hours with VFR reserves.

Steve
 
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